List of Submitted Abstracts

* Note that appearance on this list does not guarantee that the abstract has been or will be accepted. All submitted abstracts will be reviewed for suitability and technical content. Acceptance will be confirmed via email with the submitting author.

Acoustics & Applied Aerodynamics

Abstract ID: 51DCASS-067

Effect of Controlled Surface Roughness on the Jet Screech

Kaurab Gautam
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Awaiting public release.

Abstract ID: 51DCASS-085

Noise Reduction Utilizing Slot Style Injectors in Rectangular Nozzles

James Cramer
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

As general trends in acoustics emissions from military style nozzles increase [1], an increase emphasis in noise control becomes important to protect American service members especially those abord naval vessels and decrease nuisance noise for those living near military installations. Over the past year and half, the Gas Dynamics and Propulsion Lab at the University of Cincinnati has been investigating the effect of slot style fluidic injection on rectangular style nozzles. Experiments have investigated the effect of injection pressure ration, injection angle, and number of injectors through the collection of far-field and near-field acoustics, mass flow measurements, and z-type schlieren imagery. Acoustic results have shown a noise reduction of 11 dB, 5 dB, and 3 dB in the upstream, sideline, and downstream directions respectively. Imagery analysis results have shown a reduction in forward traveling acoustic waves associated with energy from the shock train, a decrease in large scale turbulent structure growth, and an interruption of the screech feedback mechanism. [1] Aubert, A., and McKinley, R., “Measurements of Jet Noise Aboard US Navy Aircraft Carriers,” presented at the AIAA Centennial of Naval Aviation Forum “100 Years of Achievement and Progress,” 2011. https://doi.org/10.2514/6.2011-6947

Abstract ID: 51DCASS-102

Hydrogen Combustor Flame Stability Characterization Amid Thermoacoustic and Hydrodynamic Disturbances Using Nonlinear Analysis Methods

Michael Larson
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Hydrogen combustors and their engine parent structures are an emerging technology requiring research and modeling so they can be understood to the point of effective and safe design and implementation. This work aims to take experimental work on hydrogen combustors and computer simulation to lay a foundational model for a hydrogen combustor. This model is intended to be capable of predicting stability states of the resulting flame based on certain input considerations and fluid behavior. Input considerations will be the equivalence ratio, the hydrogen fraction of the fuel, and geometric aspects of the combustor. The model will consider hydrodynamic fluid effects acting on the flame as well as thermoacoustic instabilities from the surrounding geometry using nonlinear analysis methods. The results of these nonlinear analyses are intended to be bifurcation maps indicating stability regions for the flame behavior based on the aforementioned critical input parameters. Understanding hydrogen fuel behavior and these main causes of instability will help provide a basis for the future of hydrogen combustor design criteria by understanding flame behavior and state sensitivity to exterior perturbations.

Abstract ID: 51DCASS-122

Effect of Upstream Geometry on Jet Noise and Flow Field of Trapezoidal Nozzles

Andrew Russell
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Circular nozzle exit geometries have been the norm for centuries, however in military jet applications, it has been suggested that nozzle exits of irregular shape may increase radar and infrared stealth. With the increase in popularity of the flying wing and blended wing body aircraft designs, a nozzle with trapezoidal cross section may improve propulsion-airframe integration on top of the stealth benefits. The goal of the current study has been to create a preliminary baseline nozzle for future trapezoidal nozzle studies, with two nozzles of differing upstream geometry being designed. Initial results have shown that these changes to the upstream geometry have a large impact on the behavior of the jet and its acoustics. Focus will be placed on the shock structure, particularly at key points such as NPR 2.70 where the two nozzles behave most differently and at NPR 3.40 where one nozzle has a discrete mode shift in its fundamental screech tone.

Abstract ID: 51DCASS-131

Hypersonic Flow Computations with Kestrel CFD Solver

Rakesh Ranjan
University of Dayton Research Institute
Nicholas Bisek
Air Force Research Laboratory

We investigate Mach 15 hypersonic flow of a five-species air mixture over a 15° blunt wedge, accounting for non-equilibrium aerothermodynamic effects. Prior investigations at this flight condition have employed a range of methodologies, including particle-based approaches such as Direct Molecular Simulation (DMS), which serves as a high-fidelity reference. Here, the same configuration is accessed using both NASA’s Fun3D and the Kestrel simulation framework, with Kestrel (kCFD) module as the flow solver. The results obtained using Kestrel exhibit improved agreement with many aspects of the DMS predictions. Key quantities are also compared to results from Fun3D which produces qualitatively similar results. Overall predictions from Kestrel are in better agreement with the DMS reference suggesting enhanced capability of the kCFD solver in capturing key non-equilibrium effects in high-speed flows.

Abstract ID: 51DCASS-133

Experimental Investigation of a Variable Collective Pitch Propeller in Near Edgewise Flight

Samuel Parlett
University of Dayton
Jielong Cai
Worcester Polytechnic Institute
Michael V. OL
California State Polytechnic University Pomona
Sidaard Gunasekaran
University of Dayton

We extend our experiments on fixed and variable collective pitch propellers in forward flight, to near-edgewise flight conditions. Different combinations of blade pitch, incidence angle, and flight speed were tested in an open-jet test section wind tunnel, at incidence angles of 75 to 100 degrees. Higher thrust and power consumption are found at higher incidence angles, which agrees with the previous study and literature. Power required at constant vertical thrust is compared across different incidence angles and advance ratios, to evaluate the efficiency of the variable collective pitch propeller, and to assess whether a rotor-borne vehicle should tilt forward in forward flight or instead remain in purely edgewise configuration and use separate horizontal thrusters for forward propulsion.

Abstract ID: 51DCASS-142

Noise Effects of Fluidic Injection Channels and Perforated Fluidic Injection

Jacob Beach
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

As military aircraft trend towards higher performance goals, increased noise levels are a natural consequence. This trend continues to exacerbate the issue of hearing safety for surrounding military personnel, especially on-board naval vessels, as well as introducing more operational noise into the lives of civilian populations surrounding military bases. This has encouraged research into active and passive noise mitigation technologies that can be used to better address these growing issues. This work builds upon previous research from the University of Cincinnati’s Gas Dynamics and Propulsion Laboratory where fluidic injection into a jet core flow has been used to reduce noise levels. The effects of structural changes in the nozzle caused by the introduction of the fluidic injection system are observed, alongside the effects of changing the injection scheme from a single row of injectors to multiple injectors along the diverging section of the nozzle. Additionally, the effects of allowing air to be entrained through the injection system by opening it to the atmosphere were investigated. Acoustic measurements in the far-field and near-field were collected alongside imaging with z-type Schlieren and mass flow measurements of the injection system. Image analysis is used alongside comparisons of acoustic data to discuss the performance impacts of each configuration.

Aircraft and UAS Design & Applications

Abstract ID: 51DCASS-013

Development of an Altitude Conditioning System for Dual Cylinder Two-Stroke Engines

Thomas Balaj
Air Force Institute of Technology
Joseph K. Ausserer and Marc D. Polanka
Air Force Institute of Technology
Jacob A. Baranski and Adam C. Brown
Innovative Scientific Solutions Inc.

Group 2 unmanned aerial systems (UAS) often utilize small two-stroke engines as primary powerplants. Expanding commercial and military use necessitates detailed performance data at various altitudes. An air cycled-based conditioning system was built to study the effects of altitude on 100-200 cc two-stroke engines. Inspired by the work of Kerner et al. this system conditions intake and exhaust air to simulate the conditions an engine experiences from sea level towards 3 km (10,000 feet). The altitude system used Commercial-off-the-Shelf equipment to cool and expand the intake and exhaust air to represent ambient conditions at specific altitudes. A turbocharger along with an air/water heat exchanger was used to expand the intake air. Subsequently, an electric supercharger along with an air/water heat exchanger was used to expand the exhaust air in a plenum that acts as a pressure reservoir. This relatively low-cost system enables performance data to be captured for UAS engines at altitude without having to fly the engine. Initial testing resulted in achieving simulated altitudes at 3 km.

Abstract ID: 51DCASS-034

Efficient Goal-Oriented Evasion via Dynamic Basic Engagement Zone Maneuvers

Alexander Denton
Air Force Institute of Technology
Donald Kunz
Air Force Institute of Technology

This study presents a novel flight path planning technique for an evading aircraft seeking to reach a destination while avoiding a single pursuer, using only turn-to-heading guidance. Building upon the analytical Basic Engagement Zone (BEZ) – a spherically capped cone representing a pursuer's reachability region (RR) relative to a moving evader – this technique takes advantage of basic kinematics to ensure the evader’s survival. Unlike traditional avoidance methods that may require drastic heading changes to stay entirely outside a pursuer's range, the proposed technique allows the evader to continue path-efficient progress toward the goal. This technique is based on the assumption that the evader initially plans to penetrate the RR along the most direct path to the goal that does not cross a denied, no-escape zone. Upon pursuer engagement, the evader executes a minimum BEZ-avoidance turn to outpace the pursuer to the limits of the RR. This approach is implemented in two variants: BEZ-Aware (for one-time launch indications) and BEZ-Evasion (for continuous sensing). The dynamic BEZ-Evasion maneuver uses real-time updates of the pursuer's position and speed to enable aggressive "cut-ins," thereby significantly increasing path efficiency relative to standard Turn-And-Run (TAR) and single-turn BEZ-Aware methods. Simulation results demonstrate that BEZ-Evasion achieves the shortest path distance by navigating the precise boundary of the threat's capability. The technique is shown to be effective across various speed ratios (μ), providing a robust framework for autonomous aircraft survivability in contested environments.

Abstract ID: 51DCASS-046

Safe Navigation in the Presence of Range-Limited Pursuers

Thomas Chapman
Air Force Research Laboratory
Alexander Von Moll
Air Force Research Laboratory
Isaac E. Weintraub
Air Force Research Laboratory

This paper examines the degree to which an evader seeking a safe and efficient path to a target location can benefit from increasing levels of knowledge regarding one or more range-limited pursuers seeking to intercept it. Unlike previous work, this research considers the time of flight of the pursuers actively attempting interception. It is shown that additional knowledge allows the evader to safely steer closer to the threats, shortening paths without accepting additional risk of capture. A control heuristic is presented, suitable for real-time implementation, which capitalizes on all knowledge available to the evader.

Abstract ID: 51DCASS-091

Conceptual Level Analysis and Design of Hypersonic Missiles with High-Speed Air-Breathing Propulsion Systems

Madison Sellers
AFIT Contractor
Joy Trimbach
Air Force Institute of Technology
José Camberos
Air Force Institute of Technology
Mitch Wolff
Wright State University

Awaiting public release.

Abstract ID: 51DCASS-125

A Comparative Study of Multimodal Cyber-Physical Alarms

Nermeen Saleh
Wright State University
Hugh Salehi
Wright State University

Unmanned Aerial Vehicles (UAVs) rely heavily on wireless communication and GPS, which makes them vulnerable to cyber-physical threats like signal jamming and spoofing. While many solutions focus on technical countermeasures, less attention has been paid to how human operators are alerted in case of an emergency. In this work, we focus on the human side of UAV security. A hardware add-on for a drone controller was developed to deliver visual, auditory, and vibrational alarms and automatically record pilot reaction time during simulated signal loss events. Twenty first-time drone operators were trained to fly a DJI Phantom 4 Advanced and exposed to each alarm modality in a randomized order during controlled flights. The results show that multimodal alerts significantly improve operator response. Auditory alarms reduced reaction time by about 74%, and vibrational alarms by about 45%, compared to visual-only alerts. While there was no significant difference between sound and vibration, both outperformed visual cues alone. Overall, this work demonstrates that integrating human-centered, multimodal alerting into UAV systems can meaningfully improve situational awareness and reduce the risk of loss of control during signal disruptions.

Abstract ID: 51DCASS-141

System-Level Validation of Dynamic Wireless Power Delivery to Electric Aerospace Platforms Using a Leaky-Wave Antenna

Michael Rogers
Wright State University
Yan Zhuang
Wright State University

Electric aerial vehicles such as drones, electric vertical takeoff and landing (eVTOL) vehicles, as well as emerging spacecraft, are inherently limited by their capacity for onboard energy. This limitation motivates research into alternative approaches to mid-flight power delivery. Wireless power transfer (WPT) via directional microwave radiation presents a potential solution for supplying supplemental energy to extend the endurance of aerial platforms or facilitate power delivery for space applications such as solar power satellites (SPS). Although WPT has been successfully demonstrated for stationary receivers, extending this technology to mobile platforms is significantly more challenging due to the continuous relative motion as alignment between transmitter and receiver must be maintained. To address these challenges, antennas that can deliver highly directive energy while adapting to the receiver’s motion are required. This research employs a leaky-wave antenna (LWA) as the transmitting device due to its high directivity, low complexity, and unique frequency dependent beam steering ability. LWAs can achieve directional scanning with significantly reduced complexity compared to phased-array systems while maintaining high gain, making them particularly attractive for next-generation aerospace systems where simplicity and robustness are crucial. This work explores the use of an LWA as a transmitting antenna to deliver continuous wireless power to a moving receiver. An experimental demonstration is planned to validate continuous, measurable WPT to a mobile receiver under laboratory conditions.

Abstract ID: 51DCASS-144

Implementing a Digital Repository for Air Vehicle Analysis, Design, and Decision Making

Samuel Atchison
AFIT Contractor
Jack Bruer
Air Force Institute of Technology
José Camberos
Air Force Institute of Technology

Awaiting public release.

Applications & Facilities

Abstract ID: 51DCASS-054

Calibration of the Saint Louis University Polysonic Wind Tunnel

Isabel Williams
St. Louis University
AJ Swartwout
St. Louis University
Mark McQuilling
St. Louis University

The polysonic wind tunnel at SLU is activated with a compressed air tank and a Fisher valve that once opened pushes a pressurized mass of air through the tunnel. The Fisher valve can be opened, releasing air at certain open percentages ranging from 0% to 105%. The mass flow rate through the conical reducer on the tunnel has been investigated throughout the range of different open percentages. It is important to understand what percent openings provide which property values for any and all future experiments. To determine the mass flow rate through the conical reducer, the wind tunnel had the sections after the conical reducer removed and two probes - a thermocouple and a pitot-static probe - positioned within the open face of the conical reducer. This setup allowed the collection of data regarding static pressure, total pressure, and temperature with the zero back pressure condition. This data was then used to calculate the density and velocity at several points throughout the open face of the conical reducer. Those values were then used to determine the mass flow rate along the opening of the conical reducer at different open percentages.

Abstract ID: 51DCASS-120

Capabilities and Applications of a Flexible Lubrication Bearing Test Rig

Andrew Hatton
Innovative Scientific Solutions Inc.
Dylan Rice
Innovative Scientific Solutions Inc.
Robert Sadinski
Air Force Research Laboratory
Justin Reinhart
Air Force Research Laboratory
Matthew Boehle
Air Force Research Laboratory

The U.S. Air Force requires high performance bearings for gas turbine engines. These bearings must withstand extreme speeds, forces, temperatures, and lubrication conditions. The Air Force Research Laboratory created the Flexible Lubrication Bearing Test Rig (FLBTR) to evaluate bearings for use in small-engine applications with multiple lubrication options. The range of capabilities of this test rig are discussed. FLBTR can accommodate a range of bearing sizes that are relevant to small engines. Engine conditions can be simulated, such as shaft speed, bearing temperature, and axial load. FLBTR can also simulate an engine’s secondary air system by controlling flow rate, temperature, and pressure. Multiple lubricant types, flow rates, and delivery methods are available. The test rig is supported by extensive instrumentation and data processing capabilities that are easily configurable. This allows the operator to monitor the health of the bearings, rig, and facility throughout a test. FLBTR is designed to be rapidly reconfigured to minimize down time and maximize its usefulness to researchers.

Combustion & Fuels

Abstract ID: 51DCASS-012

Film Cooling Applied in a Rotating Detonation Engine

Alex Thordson
Air Force Institute of Technology
Marc D. Polanka
Air Force Institute of Technology
Mauro Tagliaferri
Purdue University
Matthew Longer
Innovative Scientific Solutions Inc.

Film cooling has been proposed as a means to keep Rotating Detonation Engine (RDE) hardware cool. There have been some computational investigations showing the benefits of this. Here a small-scale RDE is utilized to evaluate this technology experimentally. Film cooling is applied to the outer wall of the combustion annulus via a pressurized air plenum. This creates a cooling layer between the detonation and the wall to reduce thermal loading. Prior research has shown that the detonation region of the RDE is challenging to film cool due to the high pressures and intense reverse flow. Therefore, the film cooling array starts above the detonation region to not only avoid affecting the detonation characteristics but also to reduce the backflow of hot gases into the coolant plenum. Testing showed that the change in fuel injection scheme had little impact to the operability of the RDE. The film cooled RDE was able to operate at varying equivalence, reactant mass flow, and coolant mass flows. As coolant flow was introduced, the wave speed and frequency remained unchanged. Wall temperature saw reductions with increasing coolant mass flow with diminishing returns when the coolant mass flow was greater than 30% of the reactant flow.

Abstract ID: 51DCASS-059

Analysis of End Plate Effect on Thermoacoustic instability using Symbolic recurrence

Tharun Srinivas Karnam Reddy
University of Cincinnati
Ephraim J. Gutmark
University of Cincinnati
Shyam Muralidharan
University of Cincinnati
Yuvi Nanda
University of Cincinnati

Interaction of the unsteady heat-release and the acoustic field of the combustion chamber leads to Thermoacoustic in rocket and gas turbine engines. Higher energy densities and low acoustic damping due to nearly closed walls of the combustion chamber which reflects acoustics waves are the major reasons for formation of thermoacoustic noise. An end plate with an orifice at the combustor exit can change the dynamics of thermoacoustic instability. Thermoacoustic instability with and without end plate is investigated and the effect of orifice size in atmospheric combustor is analyzed experimentally using nonlinear time series analysis. A quantitative comparison will be presented to understand the effect of end plate and size of the orifice.

Abstract ID: 51DCASS-071

Development and Testing of an Oxy-Fuel Burner for Engine-Representative Blade Tip Rub Experiments

Gabriel Jackson
The Ohio State University
Randall M. Mathison
The Ohio State University
Kiran D'Souza
The Ohio State University

For blade tip rub experiments, an accurate evaluation of blade tip wear and thermal barrier coating performance requires testing at engine-representative temperatures. Data obtained at the correct operating conditions are essential for improving blade tip designs, optimizing abrasive seal systems, and validating temperature-sensitive predictive models. A suite of facilities at The Ohio State University have been developed to enable tip rub testing at engine scale and engine speed. Existing facilities can produce temperatures representative of the fan and compressor section of the engine, and a new facility is being developed to generate rubs at turbine conditions. The development of a high-temperature oxygen-propane burner system has been proposed to provide controlled heating to the testing hardware. This paper will present experimental data obtained from a single prototype burner to assess its static heating ability, flame stability, and optimal settings as well as the feasibility of acquiring accurate surface temperature measurements behind an impinging flame. The results demonstrate the ability to achieve repeatable, high-temperature surface conditions. Ongoing development will extend testing to a full sub-system featuring multiple burners.

Abstract ID: 51DCASS-074

Insights into Transition to Distributed Combustion: Acoustics, Flow and Flame

Shyam Muralidharan
University of Cincinnati
Tharun Reddy
University of Cincinnati
Yuvi Nanda
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

To better design and operate the propulsion systems as per new emission norms require very low NOx emissions pushing propulsion systems to operate in lean fuel regime. Operating in lean conditions reduces thermal NOx as well as reduce fuel consumption. As fuel-air mixture approaches lean conditions, flames stability is drastically reduced and experiences enlarged flame structure making crucial to study and understand this phenomenon. This research paper investigates the transition to distributed combustion in TARS combustor burning propane fuel operating in non-premixed mode. The TARS combustor was operated at atmospheric back pressure and the inlet air is preheated to 600K. Synchronized sound pressure, OH chemiluminescence imaging and Z-type schlieren imaging was acquired at 40kHz and 50kHz for imaging respectively. Multifractal analysis was used to understand the complex nonlinear behavior of the system and SPOD to understand the flame-flow dynamics from the OH chemiluminescence and schlieren images. In the future Jet-A will be used to compare near lean blowout instabilities using liquid and gaseous fuels.

Abstract ID: 51DCASS-080

Analysis of TARS Open-Reactive Flow Temperature Distribution Using Background Oriented Schlieren

Grace Fischer
University of Cincinnati
Shyam Muralidharan
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Background Oriented Schlieren (BOS) is used to capture images of flow experiments conducted in a swirl-stabilized combustor with a lean-direct injection fuel nozzle in a Triple Annular Research Swirler (TARS) operating in a non-premixed mode. BOS is advantageous as it is a non-invasive way to capture flow fluctuations and is simple to set up as it has few components. The TARS combustor was operated at atmospheric pressure and various preheated air temperatures. The TARS nozzle was operated without the combustion chamber confinement in order to observe flow dynamics and temperature profiles by simplifying Background Oriented Schlieren calculations. TARS consists of three air passages that each have their own swirler that can be changed independently of the others. Using the TARS configuration S4500C45 and various lean equivalence ratios, the fuel split, preheated air temperature, and air mass flow rate were varied and the cases were imaged using BOS. Background Oriented Schlieren image processing of these cases generates temperature images, density gradient images, density images, and more using the quantified refractive index provided by BOS imaging.

Abstract ID: 51DCASS-081

Rotating Detonation Engine Flame-holding

Tyler Pritschau
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Rotating Detonation Engines (RDEs) are a novel approach to combusting fuel and oxidizer to generate work with a wide range of potential applications. Unlike almost all other combustion processes, RDEs consume reactants through detonative combustion. Detonations are a supersonic mode of combustion where the reaction is self-sustained by shock-induced adiabatic heating. This distinct from most reactions where the flame propagates and is sustained via diffusion of heat and mass, and has many potential advantages over other forms of combustion. Due to the supersonic nature of the flame-front, detonations can consume reactants orders of magnitude faster than other types of flames. Detonations also have the potential to extract additional usable work from a given mixture due to the pressure rise associated with the strong shock which occurs prior to combustion. A potentially interesting variation is to employ an RDE as a pilot flame component within a combustor. In an RDE piloted system, a comparatively small mass of reactants is detonated, creating a highly turbulent environment of superheated products and intermediate species. These products are mixed with the primary stream and quickly initiate combustion. This configuration offers a unique set of trade-offs when compared to the conventional RDE: (1) because only a portion of the flow experiences detonative combustion, overall pressure gain is unlikely, (2) the substantial volume of non-detonating gas may protect hardware from excess thermo-mechanical loading, (3) the fast flame-speeds associated with detonative combustion allows the pilot burner to generate products in a very small volume, helping to keep the system compact, (4) While unsteady inlet conditions are still a challenge, the cost is more acceptable since the RDE is only a fraction of the total flow, and (5) in this instance, the unsteady outlet can be considered an advantage, as it should have a positive impact on mixing and is expected to drastically decrease time to complete combustion.

Abstract ID: 51DCASS-101

Experimental Characterization of Pressure-Thrust Dynamics in a Valved Resonant Pulse Combustor

Remya M. Nair
University of Cincinnati
Shubham U. Dhadhal
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Resonant Pulse Combustors (RPCs) generate thrust through self-sustained oscillatory combustion driven by strong coupling between unsteady heat release and the acoustic field of the combustor. Understanding the baseline pressure–thrust dynamics of these devices is essential for developing methods to enhance performance and control operating modes. This work presents a detailed experimental characterization of a laboratory-scale valved RPC facility, focusing on its baseline operation and the system’s response to a modification aimed at altering the internal combustion dynamics. The experimental setup consists of a valved RPC equipped with dynamic pressure transducers at three axial locations along the RPC, a thrust measurement system, and a fuel flow metering system. The facility enables time-resolved measurements of pressure and thrust under controlled operating conditions. Baseline operation is first characterized in both the time and frequency domains. Mean and fluctuating components of pressure and thrust are analyzed to establish reference performance metrics. Fast Fourier Transforms and spectrograms are used to identify dominant resonant frequencies and their temporal evolution. Phase relationships between the spatially separated pressure sensors are examined to determine pressure wave propagation characteristics and the associated resonant mode structure of the RPC. Following the baseline characterization, the system’s response to a modification of the operating configuration is investigated. The modified cases exhibit measurable changes in dominant operating frequency and pressure wave propagation. Phase analysis between pressure locations and between pressure and thrust reveals altered internal coupling behavior. Fuel flow rate measurements correlated with thrust are used to evaluate overall propulsion performance and specific fuel consumption (SFC). The results establish a comprehensive baseline dataset for a valved RPC and demonstrate that targeted modifications to the system can significantly influence operating mode dynamics. This experimentally validated facility and analysis framework provides a foundation for future development of performance-tuned pulse combustion systems.

Abstract ID: 51DCASS-089

Recurrence Analysis of a Rotating Detonation Engine During Unstable Operation

Peter Glaubitz
University of Cincinnati
Yuvi Nanda
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

The Rotating Detonation Engine (RDE) has emerged as a promising technology to deliver several improvements over contemporary combustors. The defining characteristic of RDEs is the use of detonations to burn reactants instead of deflagrative combustion. The detonation, a combustion front coupled to a preceding shockwave, travels supersonically through the reactant mixture. As a result, combustion occurs in much shorter time frames than deflagration which is dominated by diffusion. The much faster rate of reaction may allow for the reduction in size of combustors. Additionally, the presence of the shock wave poses the possibility of increasing the pressure of the working fluid after combustion. A common issue with RDEs is unstable operation characterized by intermittent detonation, or changes to the number of detonation waves inside the combustor. This presentation focuses on a case where the RDE exhibits detonations interrupted by decay into thermoacoustic instability in a repeating pattern. Introduced is the use of recurrence plots of the signal of a flush-mounted PCB pressure transducer obtained from this case. Recurrence plots are a key tool for understanding the behavior of a non-linear system. They represent when a non-linear system returns to approximately the same location in phase space. The resulting patterns provide insight into the time evolution of the system. The recurrence plots in this study aim to help inform whether the intermittent periods of detonation and thermoacoustic are qualitatively similar, or if some additional phenomena is occurring throughout the duration of the test case.

Abstract ID: 51DCASS-090

Multiscale oscillation dynamics of unstable flames in a Triple Annular Research Swirler (TARS)

Yuvi Nanda
University of Cincinnati
Shyam Muralidharan
University of Cincinnati
Tharun Reddy
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Thermoacoustic instability in a Triple Annular Research Swirler (TARS) fuel nozzle has been analyzed in the current work to investigate multi-scale features arising from the coupling mechanism of the unsteady heat release rate and acoustic pressure. Nonlinear interactions using phase space reconstruction methods, multifractality, and spatio-temporal decomposition tools have been used to quantify the instability during intermittent transitional conditions. Time-resolved CH* Chemiluminescence images and acoustic pressure were simultaneously acquired to correlate the unsteady dynamics of the swirl-modulated flow. It was revealed that the unstable dynamics result from interactions across multiple temporal and spatial scales, with deterministic and stochastic contributions influencing the transitions in an unstable system. The flame exhibited multi-scale behavior during instability, which manifested through events such as short-term periodic behavior, intermittent blowout regions, and potential contributions towards flame flashback.

Abstract ID: 51DCASS-099

Interaction of Hydrogen-Fueled Rotating Detonation Wave with Ethylene Core Combustion

Anthony Centofanti
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Rotating Detonation Combustors (RDC) have been traditionally researched for their potential thermodynamic benefits, i.e., increase in total pressure across combustion, as compared to the Brayton cycle. However, more recently, novel RDC architectures have been increasingly studied to apply their high temperature, high pressure, unsteady transonic flow field, and other innate characteristics to a wide variety of challenges e.g., combustion speed/length, flame-holding, etc. One particularly interesting application is to employ the Rotating Detonation Wave (RDW) as an unsteady mixer on an inner reactive core flow. This work presents novel methodology alongside an optical study where the interaction of a hydrogen-fueled RDW on an ethylene-fueled core flow was performed to investigate radial penetration of combustion by the RDW. Aft-end imaging of CH* chemiluminescence at the frequency of the RDW was employed to quantify radial penetration as a result of the RDW. It was found that peak CH* intensity at the RDW frequency occurs just inside the core radius and monotonically decreases towards the center. Moreover, significant CH* chemiluminescence at the RDW frequency occurs outside the core radius implying the core-fueled ethylene recirculates back onto the hydrogen-air RDW injectors where it is mixed and detonated. The evolution of the radial CH* distribution at the RDW frequency with increasing core mass flow was additionally investigated and shown to be similar for each core mass flow rate tested. Average side imaging of the quartz combustor was also performed and corrected for 3-dimensionality with the inverse Abel transform to characterize combustion structure. CH* chemiluminescence was compared for cases operating with and without the RDW reactants (effectively as a dump combustor) and it was found that CH* chemiluminescence is significantly more concentrated within the core flow as accompanied by the RDW when compared to the dump configuration. Emission of CH* significantly diminishes near the end of the combustor, implying the RDW significantly decreases the length of core flow combustion. Lastly, with increasing core mass flow, the rotating combustion structure elongates and radial penetration is seen further aftward. Overall, significant interaction between the co-flowing streams is observed and time to complete combustion appears to be remarkably reduced.

Abstract ID: 51DCASS-100

Methods of Increasing RDE-Core Flow Interaction in a Flow Through Geometry

Brice Martinelli
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Rotating Detonation Engines (RDEs) have been a continued area of interest in propulsion and combustion research due to the theoretical efficiency improvements and total pressure gain. The majority of research on these combustors has been devoted to the characterization of the operation of the annular RDE, where the detonation wave travels circumferentially in a channel between the outer wall and an inner body. More recently, development into hollow RDEs has gathered attention due to the improvement in thermal management, weight, and differing operating regimes. A continuation of the hollow combustor is the flow-through combustor, which utilizes a core flow through the center of the RDE. This configuration allows for the use of a larger overall mass-flow, lower global equivalence ratio, and further improves thermal management. The core flow can be unfueled or fueled, the latter of which is of interest since the rotating detonation wave provides the heat necessary to maintain deflagrative combustion of the core flow. Currently, there is limited research on methods to improve the core-RDE combustion interaction. Two methods of increasing the interaction are core-flow disturbance and transient plasma discharges within the core. First, an increase in turbulent mixing between the core and RDE flows could increase the coupling between the two combustion reactions. This could be done through vortex generators, swirlers, bumps, or any other ways to perturb the core flow. Second, the discharge of nano-second pulsed non-thermal plasma discharges within the core flow offers potential operability improvements. The use of non-equilibrium plasma discharges in combustion systems has been a continued area of research and development to improve the efficiency and stability of combustors. Plasma Assisted Combustion (PAC) has been shown to reduce ignition delay, expand operating regimes, reduce emissions, and increase efficiency since the plasma discharges through air generate free radicals, which improves reactivity. Additionally, high-voltage discharges have been utilized in fuel-cracking processes by breaking down large-chain hydrocarbons into mixtures with smaller, more reactive molecules. In fueled-core flow through RDEs, the addition of non-equilibrium plasma discharges opens the door for possible core-RDE interaction improvements through both radical generation and potential fuel-cracking.

Abstract ID: 51DCASS-119

Analysis of Acoustic Modes in a Flow-Through Rotating Detonation Engine

Bret Lane
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Characteristic acoustic modes of a flow-through rotating detonation engine in operation are predicted and compared to experimental data. The solution to the eigenvalue problem of the linear acoustic wave equation is calculated analytically as well as numerically, accounting for non-uniform temperature and flow dynamics of the Core and RDC reactant flows and combustion. The first transverse mode agrees well with single wave detonations of the combustor. Other observed modes are characterized with spectral analysis of high-speed aft imaging and piezoelectric pressure sensor data, then compared to predicted acoustic modes. Non-linear interactions of the detonation wave and other observed modes are shown through bispectral mode decomposition of the aft-imaging.

Abstract ID: 51DCASS-121

Nanosecond pulsed discharges for ignition and flameholding in supersonic flows

Katherine Opacich
National Research Council
Timothy Ombrello
Air Force Research Laboratory

Plasma-assisted ignition and combustion using nanosecond (ns) discharges has garnered interest in the internal combustion engine, gas-turbine engine, and higher speed airbreathing propulsion communities due to their ability to reduce emissions, extend ignition limits, and stabilize flames. The success of ns discharges within these applied settings is, in part, due to the extensive research conducted in controlled environments that allowed fundamental understanding of the technology to grow and develop. The present work investigates how the streamer-to-arc transition previously observed by ns discharges in quiescent environments can be applied to high-speed, reactive flows, and ultimately be used as a means of flameholding within the combustor. Results initially demonstrate that ns discharges are able to achieve dielectric breakdown across a 15-20 mm inter-electrode gap in a subsonic, non-reacting flow. Similar results were also achieved along a flat wall in non-reacting supersonic flow, where discharge streamer growth from anode to cathode was seemingly aided by the dielectric surface. Finally, tests were conducted along a flat wall in reacting supersonic flow with ethylene fueling. Results from this experiment demonstrated that 1) ns discharges are capable of producing dielectric breakdown across a 20 mm gap along a wall in supersonic flow and 2) the breakdown events ignite the fuel-air mixture and generate a flame that remains until the discharge train terminates. The goal is that the present study aids future computational and experimental efforts that continue to develop and gauge the value of this flameholding technique.

Abstract ID: 51DCASS-136

Control Valve Configuration Improvement for Ignition Rig

Elizabeth Koetter
University of Dayton Research Institute

Awaiting public release.

Abstract ID: 51DCASS-143

Literature Review of Thrust Measurement Techniques for Pulse Jet Engines

Carlos Mcdonald
University of Cincinnati
Ephriam Gutmark
University of Cincinnati

Thrust is the key measurement of engine performance and determines its feasibility for design applications. Pulse jets, which have seen a resurgence of interest, present challenges due to their cyclic operation that varies between tens to hundreds of times a second. This dynamic system creates periodic thrust and pressure peaks, which cannot be measured by the same techniques used to evaluate Brayton cycle engines. The thrust for pulse jet engines is measured by averaging the results of three main measurement techniques. Those are, firstly, the direct measurement by a force transducer between the pulse jet engine and trolley on the frame. Secondly, the indirect measurement of the compression of a damping spring between the pulse jet engine and trolly and frame with a linear variable differential transducer. Lastly, the indirect measurement by a force transducer on a large plate and trolly on a separate frame in the exhaust of the engine. These methods provide accurate results to varying degrees, which is important to understand for application-based design of thrust measuring devices for pulse jet engines.

Abstract ID: 51DCASS-154

Acoustic Impedance Matching in Rotating Detonation Engines with Helmholtz Resonator Fluidic Injector Model

Grayson Razavi
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

High pressure ratios over annular combustion chambers increase the thrust produced in rotating detonation engines (RDEs); prior research has related critical detonability limits to changes in the injector equivalence ratio and reactant mass flux. The high pressure detonation wave periodically suppresses and delays reactant injection, necessitating a ‘tuned’ fluidic response. Injector geometry that decouples acoustic resonance between the feed system and detonation front may recursively stabilize the wave and prevent quenching. Unlike steady heat-release models that assume a constant mass flux for a given pressure ratio, this study uses Helmholtz resonator theory to account for fluidic inertia in the injection manifold, to maintaining a fundamental harmonic between 5-10kHz and suppressing higher order harmonics up to 40kHz. A transient simulation using a hydrogen-air mixture was used to validate this design. The injector plate was modeled with several orifice lengths (L) and plenum volumes (V) to measure acoustic damping at various resonant frequencies. High-frequency pressure monitors on the injector face and manifold were used to find the transfer function of the system and an ideal phase-lag where backflow is minimized. A broad band filter as a Helmholtz resonator gives stiffer injection, less surface area at risk of thermal failure, and dynamically suppresses acoustic impedances during mode switching.

Computational Fluid Dynamics

Abstract ID: 51DCASS-003

Tackling the Aerostructural Optimization Benchmark Problem with a Multi-Fidelity Gradient-based Approach

Markus Rumpfkeil
University of Dayton

This presentation discusses the approach and results for the benchmark model and optimization problem proposed by Working Group 1 for a Special Session on High-Fidelity Aeroelastic Design Optimization Applications and Benchmarks at the 2026 AIAA SciTech Forum. A gradient-based multi-fidelity constrained optimization framework is applied to this aeroelastic fuel burn minimization of a Boeing 717-like wing with a lift and a buffet constraint and utilizing three planform and one flow design variable (aspect ratio, sweep, taper and angle of attack). The highest and lowest fidelity levels considered are Euler and panel solutions, respectively, all combined with a modal structural solver. The coupling of the two solvers and adjoint gradient computations are accomplished with FUNtoFEM. The optimization results show that a 20% reduction in fuel burn is possible while producing enough lift for cruise without buffeting. The multi-fidelity approach outperforms the high-fidelity one in terms of both robustness and compuational cost for most starting points considered.

Abstract ID: 51DCASS-006

DES of a Mach-6 Cavity with a Forward-Facing Door

Nicholas Bisek
Air Force Research Laboratory
Elizabeth K. Benitez
Air Force Research Laboratory

Unsteady computational fluid dynamics are used to investigate flow around a partially-closed cavity (PCC) at Mach 6. These simulations were carried out in support of ground test experiments conducted at the AFRL Mach-6 Ludwieg Tube. This presentation will discuss the numerical process and observations from those simulations as the facility Reynolds number is varied and the cavity door angle and floor depth are systematically changed. The analysis provides inside into the aerodynamic instabilities present in the configuration in this extreme environment.

Abstract ID: 51DCASS-010

Computational Fluid Dynamics on Quantum Computers

Madhava Syamlal
QubitSolve Inc.

Computational fluid dynamics (CFD) is a cornerstone of aerospace design, allowing engineers to predict aerodynamic performance, thermal loads, and aeroacoustics without relying solely on costly physical testing. Despite its power, many high-fidelity CFD simulations are beyond the reach of classical supercomputers because of the immense memory and computational time required to accurately capture turbulence, multi-scale phenomena, and intricate geometries. Quantum computing represents a transformative opportunity to overcome these limitations, harnessing novel computational principles that could exponentially accelerate the solution of specific problem classes. In this presentation, we will highlight recent advancements in quantum computational fluid dynamics (quantum CFD) pioneered by QubitSolve Inc. through an NSF SBIR Phase II project. We will discuss our variational quantum algorithm for solving the Navier–Stokes equations, summarize prototype results on real quantum hardware, and present our technical roadmap to develop a minimum viable product. Our goal is to inform the aerospace sciences community about emerging quantum CFD capabilities and to engage potential collaborators in areas including algorithm development, validation test cases, and suitable aerospace applications.

Abstract ID: 51DCASS-015

Superposition of unsteady pulsed film cooling flow over an adiabatic plate through computational fluid dynamics

Matthew Knoedler
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-018

Numerical Investigations of Supersonic Cavity Flows With Novel Door Configurations

Skyler Baugher
The Ohio State University
Datta V. Gaitonde
The Ohio State University

Cavity flows are present in a wide range of engineering applications, ranging from musical instruments and automotive systems to commercial and military aircraft. In the supersonic flow regime, these flows can exhibit extreme acoustic loading, with sound pressure levels approaching nearly 160dB. Such conditions pose serious risks that must be mitigated, including damage to sensitive equipment, increased structural fatigue, and adverse effects on store release trajectories. The flow physics of these problems are governed by strongly non linear shear layer dynamics that are inherently three-dimensional, with key contributions from spillage vortices, recirculation within the cavity, and large scale ultra low frequency motions such as the tornado vortex. These low frequency structures emerge through quasi-periodic bifurcation of the shear layer and play a central role in modulating shear layer behavior, acoustic resonance, and spanwise asymmetry of the cavity flow. When cavity doors are introduced, as in weapons bays or landing gear compartments, the flow becomes considerably more complex. Interactions between the doors, the shear layer and the cavity interior can substantially amplify unsteady loading, with increases in acoustic levels of up to 20dB. These tonal amplifications are associated with three-dimensional mechanisms sensitive to undulating span-wise trapped acoustic systems as a result of the presence of doors. Door motion further introduces transient, non-stationary behavior during opening and closing, complicating both the hydrodynamic and acoustic responses. Despite its practical importance, the low frequency three-dimensional dynamics of cavity flows remains relatively unstudied, such as the tornado vortex. Much of the existing literature is limited to low-speed, low-Reynolds-number configurations with simplified geometries and boundary conditions that are not representative of realistic high-speed aircraft. Studies that explicitly address the role of cavity doors, particularly under transient operating conditions, are comparatively even more scarce. The present work addresses these gaps in literature through a combined computational and experimental test campaigns of supersonic cavity flows at Mach numbers of 1.5 and 2.0, with a cavity aspect ratio of 4.5:1:1 (length:depth:width). Both sliding and wedge type doors are considered to examine their influence on flow structure, acoustic behavior, and transient effects. A range of numerical approaches is employed, including Reynolds-Averaged Navier–Stokes, Large Eddy Simulation and hybrid RANS/LES, selected to balance physical fidelity and computational cost. In addition to the simulations, physics-based analyses such as Momentum Potential Theory and data driven techniques such as Dynamic Mode Decomposition, are applied to the three-dimensional flow field. These methods are used to isolate the dominant dynamical processes and to clarify the coupling between shear layer instabilities, ultra low frequency cavity motions, acoustic resonance, and door-induced transients.

Abstract ID: 51DCASS-021

Development of a Coupled Framework for Solving Non-Continuum Fluid-Structure Interaction Problems

Robbie Harper
University of Kentucky
Ethan Huff
University of Kentucky
Ahmed Yassin
University of Kentucky
Savio Poovathingal
University of Kentucky

Fluid–structure interactions (FSI) are ubiquitous in engineering applications, from aerodynamic loading on aircraft wings to the design of deployable structures such as parachutes for planetary missions. In many of these applications, particularly in high-altitude or planetary entry environments, the surrounding gas is rarefied, and continuum fluid models break down. As a result, accurate modeling and prediction of FSI in non-continuum flow regimes remains an open and underdeveloped problem. The Computational Thermophysics and Fluids Laboratory (CTFL) at the University of Kentucky has developed ISTHMUS (Interfacing Surface Triangles and voxels for Heterogeneous MUltiphysics Simulations), a tool that bridges voxel-based structural representations with surface meshes compatible with the Direct Simulation Monte Carlo (DSMC) solver SPARTA. While ISTHMUS enables fluid–structure coupling across disparate numerical representations, it currently functions as an external interface, limiting scalability and efficiency for large-scale, tightly coupled simulations. In this talk, I will discuss the computational challenges associated with non-continuum FSI, including data transfer and parallel performance. I will then outline ongoing and future efforts to integrate and restructure this coupling framework to enable larger, more efficient simulations without increasing computational cost, with the goal of advancing high-fidelity FSI modeling in rarefied flow.

Abstract ID: 51DCASS-032

A Mesoscale Framework for Gas–Surface Fluid–Thermal Interactions in Hypersonic Flows

Caeden Burcham
University of Kentucky
Vijay Mohan
University of Kentucky
Savio Poovathingal
University of Kentucky

Modeling fluid-thermal interactions (FTI) between gas and a solid surface accurately for vehicles in atmospheric re-entry conditions is a critical challenge in aerospace, as continuum assumptions break down due to rarefied or non-equilibrium flows. In these environments, mesoscale physics will inform the macroscopic thermal response. It is also essential to capture the underlying microstructure of carbon-carbon thermal protection systems used on these vehicles. This motivates the goal of using mesoscale, Direct Simulation Monte Carlo (DSMC), simulations to solve problems on a macroscopic scale. The FTI modeling effort builds upon the groundwork of the Interfacing Surface Triangles and voxels for Heterogeneous MUltiphysics Simulations (ISTHMUS), which is a voxel-to-surface mesh mapping tool that enables data transfer from a surface in DSMC to its corresponding voxels. This tool has been proven to work to model surface recession using finite-rate models to model oxidation and ablation at the mesoscale. When used to model fluid-thermal interactions, the Lattice Boltzmann Method can be used to model the solid interface of the carbon-carbon thermal protection system. To increase the robustness and usability of the ISTHMUS tool, as well as developing automation processes, we have systematically evaluated how the solver converges across varying pressures. Convergence is determined by the diffusion of gases to and from the surface of a carbon-carbon microstructure. The criteria for convergence include the number of flowthroughs required, the number of mean free paths in each spatial direction, particles per cell and timestep ratio which were changed to decrease the overall simulation time. These parameters were varied in the order listed to reduce the computational cost at each parameter, while maintaining convergence.

Abstract ID: 51DCASS-025

Generalized Mach formulation of Rossiter modes in subsonic to hypersonic cavities

Jeremy Redding
University of Cincinnati
Prashant Khare
University of Cincinnati
Luis Bravo
Army Research Office

This work presents the development of a comprehensive physics-based model designed to accurately estimate Rossiter modes for airflow over rectangular cavities across a range of conditions from subsonic to hypersonic, without requiring prior knowledge of the underlying flow physics. In contrast to the Heller-Bliss model, which shows significant divergence from direct numerical simulation (DNS) results at higher Mach number, the modified model aligns closely with DNS data (within 10%) at higher Mach numbers, grounded in an analysis of energy modes. By employing an effective temperature to refine sound speed calculations and subsequently utilizing this data to determine the Strouhal number, the model achieves predictions that are more in line with DNS findings. Additionally, this study establishes asymptotic limits for Strouhal numbers, contributing valuable insights to the field.

Abstract ID: 51DCASS-047

Dimensional analysis of oblique shock waves in rectangular channels

Letícia Pacheco
St. Louis University
Liam Feldmeier
St. Louis University
Liam Simmons
St. Louis University

Modern aircraft engine inlets on supersonic vehicles use the unavoidable shock waves to decelerate and pressurize the incoming flow, typically using rectangular shaped inlets. Although geometrically simple, the rectangular shapes can induce complicated shock and separation structures due to the interactions of the shocks with the boundary layers on all surfaces and corners. Rectangular inlet wind tunnel simulation data from the Air Force Research Lab was previously analyzed and dozens of dimensionless groups were found via Buckingham’s Pi theorem. This presentation will explore how Matlab optimization tools are being used to find correlations between these linear dimensionless pi groups to find a relationship between geometric and fluid dynamic variables in order to better understand shock and flow separation for modern supersonic aircraft. To find these relationships, both MATLAB optimization and custom built optimization tools were utilized. These tools were used to quantify via sum of squared errors how close of a correlation each set of pi groups had. MATLAB tools were also used to explore sufficient initial guesses for the optimization algorithms to ensure accuracy. After MATLAB was used to quantify the correlations between the linear pi groups, similar optimization tools were used to begin exploring the correlations between pi groups with nonlinear fits such as exponential and logarithmic correlations.

Abstract ID: 51DCASS-058

Comparing sharp and diffused interface methods for high-speed droplet deformation

Achyut Panchal
University of Cincinnati

Liquid droplet deformation under high-speed flow is encountered in many aerospace applications. This has also been a common and useful test case for evaluating numerical methods for modeling compressible multiphase flows. The two broad categories of compressible multiphase flow modeling are sharp-interface methods (e.g., level-set methods) and diffuse-interface methods (e.g., phase-field methods, Baer-Nunziato formulations, etc.). Even though the two can be theoretically shown to asymptote to the same mathematical formulation as the grid size approaches zero, the comparison of their numerical solutions at practical grid sizes remains unclear. 2D simulations of shock-droplet interaction at different grid resolutions will be performed in this work to compare the two methods within the same numerical framework. The results and discussion are expected to provide a key understanding of the advantages and disadvantages of both methods under practically feasible grid resolutions.

Abstract ID: 51DCASS-066

Development of a framework for modeling fluid/surface interactions with surface recession using ISTHMUS

Levi Cary
Murray State University
Caeden Burcham
University of Kentucky
Vijay B. Mohan Ramu
University of Kentucky
Savio J. Poovathingal
University of Kentucky
Tyler D. Stoffel
Murray State University

Many engineering applications involve the recession of material interfaces as mass is removed via phase transition, chemical reactions, and spallation. In many of these applications, changes to the geometry of the surface has a significant effect on the physical behavior of the material. Many models, however, assume the geometry of the surface to remain unaltered as physical effects such as fluid, thermal, and structural interactions occur. ISTHMUS, which stands for Interfacing Surface Triangles and voxels for Heterogeneous MUltiphysics Simulations, is a voxel-to-surface mesh mapping tool that can associate flux, such as mass flux, from a modeled surface to a voxel representation, allowing recession.This work presents the status of ISTHMUS-ablation, a program which leverages the capabilities of ISTHMUS to model the interaction of solid materials with gases via Direct Simulation Monte Carlo (DSMC) methods. Three-dimensional scanned images of the material are provided as a TIFF image stack and processed by ISTHMUS to convert the voxelized volume into an explicit surface representation suitable for flow simulation. The Stochastic PArallel Rarefied-gas Time-accurate Analyzer (SPARTA) solver is then used to advance the gas state in time. Local gas properties are used to compute surface mass fluxes, which directly drive geometry recession, allowing the material to recess in a manner consistent with the thermochemical state of the flow.In this talk, the results of a series of simulations modeling the ablation of carbon-carbon (C-C) composites using ISTHMUS-ablation is discussed. Carbon materials were scanned using high-resolution X-ray computed tomography (XRT) and resultant images were directly imported into ISTHMUS-ablation for simulation. Mass fluxes were computed and compiled for approximately 1000 simulations in which atmospheric pressure, temperature, and velocity were varied in accordance with the flight trajectory of an atmospheric re-entry vehicle. The method of upscaling ISTHMUS-ablation to simulate many data points is discussed, as well as future plans for improving and expanding the program for general use.

Abstract ID: 51DCASS-109

Aeroelastic optimization benchmark investigations using ESP, FUN3D, TACS, and FUNtoFEM

Neal Novotny
Air Force Research Laboratory
David Sandler
University of Dayton Research Institute

The development of next generation aircraft concepts requires toolsets that can inject higher-fidelity, multidisciplinary physics earlier into the design process. These tools need to both be developed and verified, hence the introduction of the Aeroelastic Optimization Benchmark working group. This paper examines the aeroelastic optimization of a transonic benchmark wing, as part of the Aeroelastic Optimization Benchmark, using a software toolset of Engineering Sketch Pad, FUN3D, TACS, and FUNtoFEM. In this work, we run the standard benchmark analysis cases for aerodynamic, structural, and coupled aeroelastic analysis and run optimization case1 for structural sizing. Standard benchmark results compare well with previous year’s participants and provide confidence in modeling choices. The optimization results in an 11% reduction in structural mass of the wingbox from a notional fixed pressure load to the fully coupled RANS aeroelastic optimization case. Challenges with computational cost are identified and points of mitigation are discussed.

Abstract ID: 51DCASS-111

CFD-Based Performance Optimization of a Modified Savonius Wind Turbine

Vedant Buch
University of Cincinnati
Myles Paul
University of Cincinnati
Shaaban Abdallah
University of Cincinnati
Bal Adhikari
University of Cincinnati
Kaurab Gautam
University of Cincinnati

Awaiting public release.

Abstract ID: 51DCASS-116

Additive Manufactured Turbomachinery Compressor Performance Study

Patrick Martens
Wright State University
Mitch Wolff
Wright State University
Michael List
Air Force Research Laboratory

Awaiting public release.

Abstract ID: 51DCASS-129

Machine Learned Reynolds Stress Tensor Embedded into OpenFOAM

Lincoln Dehaven
Wright State University
James Wnek
Wright State University
Mitch Wolff
Wright State University
Christopher Schrock
Air Force Research Laboratory

Awaiting public release.

Abstract ID: 51DCASS-135

Multi‐Fidelity Analysis of a Supersonic Busemann Inlet

Christopher Humphrey
University of Cincinnati
Luis Bravo
Army Research Office
Joseph D. Vasile
Army Research Office
Prashant Khare
University of Cincinnati

High-speed inlet design requires careful consideration of various factors due to the complex and dynamic multiphysics involved. The inlet shape can vary depending on the use, yet often strive to have a high efficiency across variable flight conditions. One specific type of inlet, the truncated 'sugar scoop' Busemann inlet, can now be easily produced thanks to recent advances in manufacturing technology. The result is a need for detailed design on how this inlet performs at off design conditions. These off‐design conditions can help characterize when critical flow phenomena such as engine unstart occurs. Building from previous work, a study was conducted using high fidelity and low fidelity methods to compare several inlet performance metrics. US3D was used to conduct high fidelity simulations on the DOD HPC. The low fidelity tool is Manta and it was used to optimize/explore a design space. Based on the compared metrics the basic trends are captured across all levels. During the design process different tools can be applied to minimize computational cost and increase design exploration.

Abstract ID: 51DCASS-153

Study of Helmholtz-Decomposed Navier-Stokes Equations for Unsteady Boundary Conditions

Bal Adhikari
University of Cincinnati
Kaurab Gautam
University of Cincinnati
Nabin Khanal
University of Cincinnati
Shaaban Abdallah
University of Cincinnati

Incompressible Navier-Stokes (NS) equations can be reformulated using the Helmholtz decomposition, wherein the velocity field was expressed as the sum of rotational and potential components. In the work by Kaurab et al. -the steady-state formulation of these equations was successfully solved and validated across different Reynolds numbers, demonstrating the effectiveness of the decomposition in capturing flow characteristics under steady boundary conditions. However, real-world fluid dynamics problems often involve unsteady boundary conditions, which necessitate an extension of this approach. Incorporating unsteady boundary conditions into the decomposed NS framework for the published work, where it is transformed into an explicitly steady-state form in terms of primitive variables, is studied in this work. Unsteady results are validated against comparable results obtained using other methods. The study is able to validate the independence of the resulting system of equations from the cell Reynolds number. Grid-independence tests and time-independence tests have been carried out.

Data Analysis & Uncertainty Quantification

Abstract ID: 51DCASS-001

Uncertainty Quantification for Transient Thermal Management

Rama S Gorla
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-094

Adaptive Multi-Fidelity Machine Learning for Nonlinear Buckling Prediction of Imperfect Cylindrical Structures

Samuel Salupo
Wright State University
Harok Bae
Wright State University
Mishal Thapa
Clarkson University
Sameer Mulani
The University of Alabama

This work presents an adaptive multi-fidelity machine learning approach for nonlinear buckling prediction of thin walled cylindrical aerospace structures subject to geometric imperfection. High fidelity nonlinear finite element simulations are performed using MSC Nastran, while intermediate fidelity datasets are generated by systematically varying nonlinear solver and control parameters to reduce computational cost. These datasets are incorporated into an emulator embedded neural network framework with adaptive sampling driven by effectiveness based Bayesian optimization. The methodology enables efficient exploration of nonlinear buckling behavior while preserving predictive accuracy relative to full high fidelity analyses. The approach is demonstrated on cylinder buckling load prediction and is motivated by applications in structural reliability and uncertainty aware aerospace design, where computational expense and model fidelity must be carefully balanced.

Abstract ID: 51DCASS-117

The Effect of Fatigue on Multitasking Performance in Automated Operational Environments

Stacie Severyn
Wright State University
Hugh Salehi
Wright State University
Cogan Shimizu
Wright State University
Elizabeth Fox
Air Force Research Laboratory

Awaiting public release.

Digital Engineering

Abstract ID: 51DCASS-030

Algorithmic and Precision Tradeoffs in GPU-Accelerated CFD Solvers

Maya Sivakumaran
The Ohio State University
Datta V. Gaitonde
The Ohio State University

The modernization of legacy high-fidelity computational fluid dynamics (CFD) codes for GPU-accelerated computing is increasingly necessary to meet growing demands for simulation throughput and energy efficiency. However, the algorithmic structure of existing CFD solvers imposes nontrivial constraints on GPU implementation. Differences in data dependencies, synchronization requirements, and numerical sensitivity can strongly influence achievable performance, scalability, and solution fidelity on CPU–GPU systems. While directive-based programming models such as OpenACC facilitate GPU porting, algorithm-dependent performance and precision tolerance remain poorly characterized in practical CFD workflows. This work investigates these challenges through a controlled evaluation of algorithmic and precision tradeoffs in GPU-accelerated CFD solvers using a consistent OpenACC-based framework that isolates the influence of solver structure and numerical precision on GPU performance and solution accuracy. Representative iterative solver algorithms are examined under double-, single-, and mixed-precision configurations to assess how solver structure and numerical precision interact with GPU execution. Performance is evaluated using runtime and energy metrics, while numerical behavior is assessed through convergence characteristics and error norms on controlled test cases. Rather than proposing a single optimal strategy, this study characterizes the performance–accuracy tradeoffs governing GPU-accelerated solver behavior and identifies conditions under which reduced precision may be applied without unacceptable loss of accuracy. These results are intended to inform engineering decisions during the modernization of legacy CFD codes, supporting more efficient and sustainable CFD workflows for aerospace applications.

Abstract ID: 51DCASS-107

Towards Accelerated CFD for Hypersonic Vehicle Analysis

Brandon Smith
Parallax Advanced Research
Lauren Mackey
Parallax Advanced Research
Oliver Stolley
Parallax Advanced Research

Parallax Advanced Research and its affiliate, the Ohio Aerospace Institute, are establishing a scalable digital engineering framework that combines fluid dynamics codes, multidisciplinary analysis, and automated modeling workflows to support government and industrial hypersonic programs. This architecture accelerates hypersonic trade studies and verification by automating grid ingestion, input generation, and execution, reducing reliance on specialized aerothermodynamics expertise. Our goal is to support continuous advancement in U.S. hypersonic systems development, which requires digitally integrated engineering, manufacturing, and sustainment approaches that reduce development timelines while maintaining credible prediction accuracy in extreme flight regimes. Furthermore, we seek to reduce the barrier to entry of conventional hypersonic computational fluid dynamics (CFD) workflows, which are often manually intensive, siloed, and dependent on specialized expertise, limiting their applicability to early-phase design, trade studies, and verification planning. These efforts will support the flow of CFD expertise from a relatively small industrial base and academia to a wider workforce, enabling widespread application of advanced tools needed for hypersonic systems development. This work presents recent and ongoing advancements in Parallax/OAI’s hypersonic fluid dynamics toolchain, including integration of CFD within a multidisciplinary digital workflow, coupling strategies for complementary physical models such as aerothermoelastic response prediction, and automated workflows that enable rapid design iteration on high-performance computing resources. We demonstrate a representative workflow using NASA’s CBAero linked to a 6-degree-of-freedom (6DOF) rigid body model. CBAero is a fast-running panel model that provides physics-based aerodynamic and aerothermal data to inform digital system models supporting early-phase trade studies, verification activities, and downstream ground-test planning. The framework automates ingestion of the triangulated surface grid into CBAero, generation of the input deck, execution of CBAero, and execution of the downstream 6DOF model. This capability is intended to lower the barrier to entry for high-enthalpy flow simulation, enabling effective use by the broader community without expert-level specialization in hypersonic aerothermodynamics. Initial implementations rely on simplified modeling assumptions but will be expanded to include various numerical tools. Planned enhancements include support for higher-fidelity computational fluid dynamics, through the replacement of CBAero with higher fidelity models; models that incorporating chemical nonequilibrium, thermal relaxation, advanced turbulence modeling (including resolved turbulence methods), and boundary-layer transition prediction; addition of complementary physical models, such as material thermal response and ablation; and incorporation of advanced quality-of-life features like automatic meshing for specific classes of geometry. The overall architecture will follow a model-based systems engineering (MBSE) approach wherein individual models are placed in siloed containers that communicate in a one- or two-way manner via virtual network interfaces. The interfaces between specific system models will be strictly defined so that substitution of models will be feasible, provided there is a translation layer that converts code output into the format required by the network interface. We will focus our CFD model selection on codes that incorporate adaptive meshing techniques to reduce the burden and error associated with the initial mesh. Collectively, these capabilities strengthen the digital engineering foundation necessary for accelerated hypersonic system maturation and relaxing the need for expert level knowledge to run hypersonic codes.

Experimental Methods

Abstract ID: 51DCASS-026

Dynamic Controls of the 3-Dimensions Helmholtz Cage using PIDA Controls

Long Pham
University of Cincinnati
John Radey
University of Cincinnati
Jack Oakenful
Carnegie-Mellon University
Ma Ou
University of Cincinnati
Andrew Barth
University of Cincinnati

Awaiting public release.

Flight Dynamics & Controls

Abstract ID: 51DCASS-022

Design and Planned Flight Evaluation of an Active Fin Airbraking System

Mubasshir Khan
University of Kentucky
Savio Poovathingal
University of Kentucky

Active aerodynamic braking in sounding rockets is commonly implemented using deployable airbrake panels. This paper presents the design and planned experimental evaluation of an alternative active fin–based airbraking system, in which a four-fin, servo-actuated system mounted within a structural coupler is used solely to modulate aerodynamic drag without providing active attitude stabilization. The system repurposes an active fin control e-bay to function as a software-defined airbrake, eliminating the need for dedicated drag surfaces. The proposed method employs a control allocation strategy in which diametrically opposite fins are commanded to equal-magnitude, opposite-sign deflections. Because fin deflection increases aerodynamic drag largely independent of deflection direction, while the resulting control moments reverse sign with deflection, this configuration is expected to increase drag while canceling roll, pitch, and yaw moments under near-axial flight conditions. A braking-only control mode is implemented to generate continuous, reversible drag modulation during ascent, with onboard inertial and altitude sensing used to characterize system behavior. This paper focuses on the mechanical design, control architecture, and safety constraints of the coupler-mounted fin-based airbraking system, along with a structured multi-flight test plan intended to evaluate braking effectiveness, the ability to reach a desired apogee, and any unintended rotational effects produced during braking. Flight testing is planned to use identical vehicles and motors to isolate braking behavior. The results of this work are expected to establish the feasibility of active fin–based airbraking and to provide a foundation for future integration of combined stabilization and braking using a single fin actuation system.

Abstract ID: 51DCASS-023

Building quantum into aerospace: virtual flight control surfaces from fusion-inspired superconductivity

John Bulmer
Air Force Research Laboratory
Brice Hall, Kadyn Tackett, Jake Blue, Sabrina Eddy, Mary-Ann Sebastian
Air Force Research Laboratory
Charlie Ebbing, Chris Kovacs, Tim Haugan
Air Force Research Laboratory

Superconductivity is one of the few quantum phenomena where a single quantum wavefunction governs the behavior of a macroscopic object. Recent advances in fusion research have driven the development of extraordinarily powerful (greater than 20 T) and lightweight superconducting electromagnets; however, the application of this emerging class of magnets to aerospace systems remains largely unexplored. Here, we propose mechanical-free, motionless, and near- instantaneous virtual flight control surfaces based on magnetohydrodynamic (MHD) interaction between boundary-layer airflow and a spatially uniform magnetic field projected over an airfoil surface using a novel superconducting Halbach array. This implementation of a linear Halbach array, enabled by high-temperature superconductors, provides exceptional magnetic field strength (≈3 T at a 10 cm standoff in the free airstream) per unit mass relative to permanent magnets, while offering unique spatial and temporal tunability. Air conductivity is enhanced through either high-speed flight conditions or embedded arrays of nanosecond surface dielectric barrier discharge (ns-SDBD) actuators. First-principles analysis identifies the relevant flight regimes and magnetic-field requirements for effective control authority; that is, flight conditions that make the Hall parameter =1 (representing peak MHD effectiveness); the Stuart parameter =1 (representing full airflow stoppage); Stuart parameter =0.1 (representing a boundary separation perturbation). We study regimes where air conductivity is increased by high-speed frictional heating; followed by conductivity enhancement from the ns-SDBD actuators; followed by supplementary Lorentz forces from the ns-SDBD current pulse. The thermodynamic air properties were taken from the normal shock relations (greater than Mach 1) and the isentropic compressible relations (less than Mach 1). The air conductivity and electron mobility were estimated using statistical models derived from an agglomeration of multiple literature sources selected for relevance. Sufficient control force is found over a wide operational window, although this must be weighed against the ns-SDBD pulse duration and its surface-only influence. We also report recent progress toward enabling technologies, including mechanically robust, flexible superconducting wire based on hybrid fullerene–carbon-nanotube cables.

Abstract ID: 51DCASS-077

Model-Based Design and Validation of Closed-Loop Aerodynamic Control for High-Powered Model Rockets Using a Python Digital Flight Environment

Sebastian Toledo
Cedarville University
Sebastian Mackliff Davalos
Cedarville University
Joseph D. Miller
Cedarville University

Accurate prediction and control of high-powered rocket flight dynamics remain challenging due to nonlinear aerodynamics, environmental uncertainty, and limited fidelity in existing commercial simulation tools. This work presents a model-based digital flight environment developed in Python, which leverages open-source library RocketPy, to support the design, tuning, and validation of closed-loop aerodynamic control systems for high-powered rockets. The framework combines a physics-based digital flight model with CFD-informed aerodynamic estimates to represent actively varying aerodynamic surfaces, including deployable airbrakes and canard-induced spin. The model enables real-time prediction of flight trajectories and the corresponding control actions necessary to regulate apogee under varying atmospheric and vehicle conditions. The airbrake system is composed of three external control surfaces designed to maintain a near constant deployment, ensuring only minor adjustments during flight to attain the desired apogee. The airbrake’s design balances key factors such as the sizing of the apogee control housing, the dimensions of the control surfaces, the mechanical advantage, and the mechanism actuation speed to ensure an apogee within one percent relative error. The resulting digital testing environment enables rapid iteration on controller logic prior to flight, reducing risk while improving performance in altitude-critical missions such as the NASA Student Launch Initiative and regional collegiate rocketry competitions. This work demonstrates the applicability of model-based digital engineering techniques to active aerodynamic control problems in experimental aerospace systems.

Abstract ID: 51DCASS-087

Visual Servoing-Based Autonomous Landing on Austere Runways

Liam Mckenna
AFIT Contractor
Clark Taylor
Air Force Institute of Technology
Jeremy Gray
AFIT Contractor
Jason Bowman
Air Force Research Laboratory

As small-UAS (sUAS) vehicles rise to prominence for commercial, academic, and military use, autonomous operation is still limited by the capability of sensor systems to provide sufficient situational awareness. RF-based systems (such as GPS, radio localizers, etc.) provide accurate measurements in controlled spaces, where existing infrastructure is leveraged to create a reliable source-of-truth for aircraft positioning. In uncontrolled and unprepared (so-called "Austere") conditions, these systems are not practical due to degradation by jamming/spoofing/obscuring communications or simply lacking supporting infrastructure (e.g. ground-based sensing systems). Fixed-wing autonomous landing presents a high safety risk, demanding high performance to avoid incidents. In austere environments, autonomous landing is particularly challenging (conventional runways are typically well-marked and equipped with lighting systems, sometimes additionally ground-based localization). For a fixed-wing sUAS vehicle to land on an "Austere Runway", the guidance and control system cannot rely on conventional sources of truth to perform a safe landing. To address this challenge, a methodology for sUAS guidance and control during landing on an Austere Runway is proposed, which uses egocentric information such as inertial measurements and visual cues, which will be known a priori. In this work, a simple runway endpoint detection algorithm is demonstrated to provide control inputs for the landing of a fixed-wing sUAS on approach to an Austere Runway. It is assumed that the selected runway's location and appearance are known a priori (such as that obtained from satellite imagery). The experimental setup includes a detailed simulation of a simple sUAS sensor suite composed of an Inertial Measurement Unit (IMU), Computer Vision System, Barometer, & Airspeed Sensor, which are integrated into a Software-In-The-Loop (SITL) simulation framework for aircraft dynamics and flight control. Visual feedback about the environment landmarks is produced using a simplified mapping from world position to inferred position in the camera frame. The sensor information is combined to produce inferential feedback about the aircraft's approach to a closed-loop controller. The resulting system leverages computer vision and visual servoing to control the sUAS into the proper runway alignment and glide path in an austere setting. A robustness analysis is performed to evaluate the performance of the visual-servoing controller. Success criteria for a landing is defined according to designated touchdown velocity and pose requirements. A set of initial conditions are defined for an in-flight sUAS approaching the austere runway and evaluated, including either alignment or rotation offsets in approach start. Final results from our analysis shows that the system is capable of robust landing control when the runway is in view, based on fulfillment of the landing criteria, even if the aircraft's approach is entirely misaligned with the runway centerline. The implications of this system extend to fully autonomous landing of platforms in austere or minimally-prepared and GPS-denied environments, which could provide immense capability for the distribution of autonomous platforms in environments which are unsuitable for conventional systems.

Fluid Dynamics

Abstract ID: 51DCASS-002

Numerical Simulation of Pulsed Blowing Coanda-Jet Flow Control for a Wing Section

Donald Rizzetta
Air Force Research Laboratory
Daniel Garmann
Air Force Research Laboratory

Large-eddy simulations were carried for the flow over a wing section, using pulsed blowing Coanda-jet control. The section geometry consists of a modified supercritical airfoil section, with a trailing-edge Coanda surface. Because the configuration has no moving parts, the mechanical complexity and weight may be reduced. The configuration corresponds to an experimental investigation, that provided limited data. High-fidelity solutions were obtained to the unsteady three-dimensional Navier-Stokes equations, at a Reynolds of 475,000,freestream Mach number of 0.1, and angle of attack equal to 5.0 degrees. As means of decreasing mass-flow requirements, pulsed blowing was supplied to a jet flowing over a trailing edge Coanda surface. Parametric studies were performed for the pulsing frequency and duty cycle. Results are compared among the various cases, and with previous steady-jet simulations. Adverse effects of low-frequency pulsing were uncovered, and an optimal frequency was identified. Features of the time-mean and instantaneous flowfields are characterized.

Abstract ID: 51DCASS-005

Aerodynamic Instability from a Partially-Closed Cavity in Hypersonic Flow

Elizabeth Benitez
Air Force Research Laboratory
Nicholas Bisek
Air Force Research Laboratory

A joint experimental-computational investigation into the aerodynamic behavior of a generic door-cavity model was conducted in Mach-6 flow. The experimental model, featuring a flat plate with a rectangular cavity and a hinged forward-facing door, revealed a powerful, low-frequency pressure oscillation at approximately 500 Hz for a specific configuration with a 7.5° door angle and 25-mm cavity depth. Crucially, this instability is not attributable to established empirical models for cavity flows, such as the Rossiter mechanism or closed-box acoustic resonance. Instead, the phenomenon is driven by the periodic growth and collapse of a large separation bubble that forms on the flat plate upstream of the cavity. To further elucidate the flow physics, high-fidelity Detached Eddy Simulations (DES) were conducted, providing a detailed visualization of the complex, unsteady flow interactions and complementing the experimental data. Systematic variation of the geometric parameters revealed that the 500-Hz fluctuations were confined to a narrow operational window of door angles, observed only between 5.0° and 7.5°. Furthermore, tests with shallower cavities demonstrated that the onset of the instability could be delayed to a higher freestream Reynolds number. The combination of experimental and numerical results provides a critical foundational dataset on the aerodynamic performance of a hypersonic forward-facing door, identifying a novel instability mechanism of direct relevance to vehicle design and integration. Distribution Statement A: Approved for Public Release; Distribution is Unlimited. PA# AFRL-2025-5843; Cleared 12/30/2025.

Abstract ID: 51DCASS-020

Characterization of Instability Modes in Hypersonic Flow over a Cone-Cylinder-Flare

Chandan Kumar
The Ohio State University
Unnikrishnan Sasidharan Nair
Florida State University
Datta V. Gaitonde
The Ohio State University

Numerical and theoretical analyses are performed to examine instability due to freestream acoustic disturbances in hypersonic flow over a cone-cylinder-flare (CCF) configuration at Mach 6. The geometry and flow conditions are patterned on an experimental study conducted in the BAMQ6T facility at Purdue. The flow exhibits several complex features, including an attached boundary layer over the cone, shock/boundary layer interaction (SBLI) over the cylinder and flare, a separation bubble at the corner, and reattachment on the flare, each contributing to collectively yield multifaceted instability mechanisms. The effects of changing wall thermal conditions from the experimental cold isothermal (TW = 303 K) to adiabatic (hot) are also examined. In the case of a hot wall, the separation bubble size increases significantly compared to the isothermal case, leading to altered shear-layer dynamics and delayed reattachment with steeper gradients. Linear stability analysis of the basic state reveals first- and second-mode disturbances as distinct spectral bands. Towards the rear of the cone, bispectral analysis reveals prominent amplitude modulation, where interactions between the second mode and its higher harmonics are detected. These interactions may contribute to spanwise variations prior to separation over the cylinder. The frequencies of instabilities shift towards lower values within the separation bubble, where multi-arm spectral patterns indicate the presence of competing instability modes; these lower-frequency disturbances amplify within the separation bubble as observed in the past. Strong phase-locked triadic interactions are observed in the separation bubble, while over the cone, these are mostly confined near the nose and along the leading-edge shock. Further downstream, the reattachment zone over the flare exhibits the combined effect of boundary layer and shear-generated waves. Nonlinear effects are further amplified in the reattachment region, where complex flow structures emerge, ultimately affecting the reattachment process and the flow downstream.

Abstract ID: 51DCASS-027

Impact of Fins of the Unsteady Base Flow of a Supersonic Projectile

Steven Murawski
The Ohio State University
Datta V. Gaitonde
The Ohio State University

Delayed detached-eddy simulations are conducted at Mach 2 and 12 degrees angle-of-attack to explore the influence of fins on the wake of a slender projectile. The results are first validated against available experimental data. Mean quantities and modal analysis techniques highlight the primary flow features in the wake and the key influences of the fins. The results indicate that when fins are present, two distinct frequencies emerge, each associated with different primary coherent structures. The first, a low frequency (St = 0.03) is shown to be associated with a breathing motion of the recirculation region and recompression shock. This frequency is also present in the unsteady axial force coefficient trace, indicating that the breathing mode impacts the forces on the vehicle. The second frequency is an order of magnitude higher (St = 0.3) and shown to be related to a wake shedding mode and vortex roll-up mode. A detailed comparison with the finless configuration, and the effect of roll on these structures highlights the overall dynamics experienced by slender projectiles in their trajectories. Identification of the key frequencies and their corresponding flow structures facilitates the exploration of targeted control strategies to mitigate or modify the flowfield for better trajectory planning.

Abstract ID: 51DCASS-033

Amplification Mechanisms in a Supersonic Dual-Stream Rectangular Jet

Mitesh Thakor
The Ohio State University
Datta V. Gaitonde
The Ohio State University

Coherent structures play a central role in governing the dynamics, mixing, and acoustic behavior of turbulent jets, particularly in complex multi-stream configurations where multiple shear layers interact. While detailed studies have established the dominant mechanisms of nominally two-dimensional (2D) shear layers, realistic nozzle geometries introduce proximal surfaces and geometric constraints that fundamentally alter shear-layer behavior and promote three-dimensional (3D) dynamics. This work investigates the spatiotemporal coherent structures and amplification mechanisms in a supersonic dual-stream rectangular jet using large-eddy simulations and mean-flow-based analyses. The nozzle geometry comprises three primary shear layers: an upper shear layer (USL) formed between a Mach 1.23 core stream developing along an upper expansion-ramp stream and the ambient; a splitter-plate shear layer (SPSL) generated by the interaction of the Mach 1.23 core stream and a Mach 1 bypass stream at a splitter-plate trailing edge (SPTE); and a lower shear layer (LSL) that develops downstream of the aft deck as the flow mixes with the ambient environment. These shear layers evolve within a highly complex flow field containing shock-shear-layer interactions, boundary layers, and corner vortices. A clear separation of dynamics across frequency bands becomes evident with Spectral Proper Orthogonal Decomposition (SPOD). Broadband low-frequency content is dominated by highly 3D coherent structures originating in the USL and LSL, whereas high-frequency tonal content is associated with a predominantly 2D instability within the SPSL. To establish the physical origin of this tonal response, the SPSL is first examined in isolation. SPOD identifies Kelvin-Helmholtz (KH) wavepackets as the most energetic coherent structures at the dominant tonal frequency. Linear resolvent analysis of the time-averaged flow shows peak amplification at the same frequency, confirming the KH instability as the primary amplification mechanism in the SPSL. The role of nonlinear quadratic interactions in sustaining the tonal response is extracted with bispectral mode decomposition. A componentwise input-output analysis identifies the SPTE as the most receptive region for perturbation growth. Forced simulations show strong agreement between pressure modes obtained from dynamic mode decomposition and those predicted by linear input-output analysis, supporting the relevance of linear mechanisms in the SPSL dynamics. The analysis is then extended to fully 3D dynamics of the USL and LSL using triglobal resolvent. Low-frequency response modes are excited by forcing localized near the nozzle geometry and are governed by 3D KH-type instabilities. These modes generate streamwise vortices originating at the nozzle corners, which drive the axis-switching behavior characteristic of rectangular jets. Wavemaker analysis further shows that these corner vortices participate in a self-sustaining low-frequency feedback mechanism. These findings provide a foundation for improved modeling and control of shear-layer dynamics in practical multi-stream jet configurations.

Abstract ID: 51DCASS-036

Effect of Prescribed Panel Mode Shapes on a Compound-Swept Turbulent Shock–Wave/Boundary-Layer Interaction

Anshul Suri
The Ohio State University
Datta Gaitonde
The Ohio State University
Jack McNamara
The Ohio State University

Shock-wave/boundary-layer induced fluid–structure interactions play a critical role in shaping the aerodynamic performance and structural response of high-speed vehicles. Turbulent shock-wave/boundary-layer interactions (SBLIs) are particularly sensitive to surface deformations, with their response governed by the receptivity of the interaction to induced disturbances. In this study, the response of a strongly three-dimensional SBLI generated by a canonical double-fin configuration is investigated using large-eddy simulations. This configuration serves as a representative abstraction of the complex, interacting features encountered in realistic flight environments. The dominant spatio-temporal characteristics of the undisturbed baseline flow are used to inform the placement and actuation of a compliant surface panel embedded within the interaction region. Two representative panel mode shapes, Mode (1,1) and Mode (2,1), are forced at the frequency of the separated shear layer. The analysis is carried out within a one-way structure-to-fluid framework, in which the flow responds to the imposed surface motion while feedback to the structure is suppressed to enable an efficient and controlled investigation. The imposed panel motion alters local viscous–inviscid interactions, leading to enhanced mean flow separation. These modifications persist downstream of the panel and produce significant changes in surface pressure distributions along the shock structure. Panel forcing intensifies shear-layer unsteadiness and modulates near-wall turbulence by early disruption of the streak regeneration cycle and delaying the downstream recovery to upstream boundary-layer-like anisotropy. The resulting shock unsteadiness is strongly influenced by the imposed panel dynamics, with its temporal characteristics exhibiting a clear dependence on the selected mode shape. Nonlinear interactions within the forced system are examined using a moving-mesh-compatible, Lagrangian modal analysis based formulation of Bispectral Mode Decomposition. The analysis reveals nonlinear triadic interactions that transfer energy between the fundamental forcing frequency and its harmonics, establishing a cascade of coupled modal interactions. A complementary time-localized, phase-based analysis demonstrates pronounced phase synchronization between the panel motion and shock oscillations. Transient phase slipping is observed, along with the emergence of preferred phase differences that depend on the prescribed panel mode shape, highlighting the role of phase synchrony in governing the forced SBLI response.

Abstract ID: 51DCASS-044

Wake Structure of Upswept Afterbodies with Geometric Modifications

Jacob Biesinger
The Ohio State University
Datta Gaitonde
The Ohio State University

Military cargo aircraft fuselages are designed with a large, flat, upswept trailing surface to accommodate ramp doors. The resulting turbulent wake is dominated by a complex, unsteady, counter-rotating longitudinal vortex pair, which poses safety and performance concerns. Previous studies have focused on a canonical surrogate aft body configuration consisting of a cylinder truncated at an angle. While this model has guided a foundational understanding of the wake, the results do not account for many critical geometric realities of cargo wakes. To address this knowledge gap, this work considers several modifications to the basic model, specifically edge rounding, a square cross-section, an embedded open bay, and a door ramp. High-fidelity Large Eddy Simulations (LES) are employed to assess the aerodynamic effects of each modification to the model. Diverse analysis techniques are applied, with a focus on modal analysis tools, to characterize the mean and unsteady topology of each flow field. The results demonstrate that model modifications produce substantial alterations to the longitudinal vortex system. Edge rounding introduces relatively low-frequency oscillations in the separation location and increases wake complexity. A square cross-section generates a larger, asymmetric vortex pair and contains lower frequencies in the immediate wake. Bay and ramp features further modify vortex size, coherence, and dissipation, underscoring the role of afterbody geometric configuration in shaping the wake.

Abstract ID: 51DCASS-048

Dimensional Analysis of Oblique Shock Waves in Rectangular Channels

Liam Feldmeier
St. Louis University
Liam Simmons
St. Louis University
Letícia Pacheco
St. Louis University
Mark McQuilling
St. Louis University

Abstract ID: 51DCASS-065

Airfoil gust mitigation using jet spoiler actuation

Spencer Stahl
Air Force Research Laboratory
Caleb J. Barnes
Air Force Research Laboratory

Large eddy simulations of a laminar Mach 0.1 airfoil subject to gust disturbances are conducted, investigating the effectiveness of jet blowing as a spoiler-like control mechanism. Two transverse gusts are tested that significantly increase the airfoil effective angle of attack to 18 and 27 degrees, imparting strong lift forces accompanied by flow separation and a leading-edge vortex for the latter case. The jet spoiler is located on the upper surface towards the rear of the airfoil and has an optimal blowing direction of 110 degrees, pointed into the freestream flow. The jets stagnation with the freestream produces a high-pressure region on the upper surface in front of the jet and accelerates flow from the lower surface via the entrainment of a trailing edge vortex. The combined effect successfully mitigates the gusts peak lift and duration by up to 50%. The analysis also characterizes the jets modulation of vortical dynamics, surface pressure, and skin-friction responses throughout the gust encounter.

Abstract ID: 51DCASS-070

Evaluation of Taylor’s Frozen Flow hypothesis and the Elliptic Approximation model in turbulent free jets using 100-kHz, 2D Particle Image Velocimetry

Madelyn Torrans
Cedarville University
Seth K. Mitchell
Cedarville University
Joseph D. Miller
Cedarville University

Understanding turbulent flow development and the dynamics of turbulent eddies in highly sheared free jets is applicable to many important aerospace challenges including jet noise from military and commercial air vehicles, surface cooling, and jet mixing. Computational fluid dynamics simulations and simple correlation methods are commonly used to study turbulent flow, but it is necessary to validate these results. In this work, turbulent flow velocity data collected using high-speed, two-dimensional particle image velocimetry is used to compare the prediction accuracy of Taylor’s Frozen Flow hypothesis and the Elliptic Approximation model. While spatiotemporal correlations and Elliptic Approximation models have been used previously to study turbulent flows, the use of highly accurate, experimentally collected data in the validation process is unique. Axial and radial velocity are estimated from time-space correlations using Taylor’s hypothesis and the Elliptic Approximation model. Accuracy of each model is quantified in both high- and low-shear regions of the flow field by comparing the estimated velocity to the measured velocity. Based on this analysis, suggestions are made on the application of each model to different regions of highly-sheared turbulent flows.

Abstract ID: 51DCASS-110

Analysis and Control of Bell-Shaped Lift Distributions at Off-design Conditions

Charles Cain
University of Dayton
Sidaard Gunasekaran
University of Dayton

A wing designed with a bell-shaped lift distribution has been shown to suppress the conventional wingtip vortex in the wake at a specific design angle of attack. In this study, methods for modifying the lift distribution at off-design angles of attack were examined analytically and using RANS CFD simulations. Microtabs are small devices that have been studied for load alleviation on wind turbine blades. With this in mind, microtab-like shapes were applied at specific spanwise locations and heights to alter the local lift distribution along the wing. Initial simulation results suggest that this method can reproduce a near bell-shaped lift distribution and successfully suppress the wingtip vortex even at off-design angles of attack. This work is part of a continuing effort to understand and apply the physical mechanisms underlying the unique wake properties of bell-shaped lift distributions and to develop methods for extending their applicability in future studies.

Abstract ID: 51DCASS-115

Characterization of Rotary Atomizer Spray Geometry Under the Influence of a Propeller

Brock Greenwood
University of Dayton
Abdul Khan
University of Dayton
Megan Bender
University of Dayton
Siddard Gunasekaran
University of Dayton

Recent advancements in aerial spraying have driven a shift toward rotary atomizers on unmanned aerial vehicle platforms because they produce uniform droplet sizes at low flow rates with minimal clogging. However, the interaction between rotary atomizer plumes and UAV propeller wakes remains poorly understood. This study uses an optical spray patternator to characterize the three-dimensional spray geometry of a rotary atomizer operated beneath a single 17×7 APC propeller and a dual propeller configuration in the University of Dayton Low Speed Wind Tunnel Laboratory. Intensity based reconstructions quantify changes in spray shape, diameter, and droplet concentration as functions of nozzle rotational speed and distance from the nozzle. A single propeller contracts the natural umbrella shaped plume into a column but causes the high-intensity core to erode rapidly, producing a fragmented spray and a diffused low-density halo. The dual propeller configuration generates a stronger, more uniform downwash that preserves a broad cylindrical high-intensity core, reduced low droplet density zone, and keeps the energetic region closer to the spray center. These results show that multi propeller flow fields can stabilize rotary atomizer sprays and improve the distribution of deposition relevant droplets in UAV spraying applications.

Abstract ID: 51DCASS-127

Experimental Investigation of Dynamic Pitching Effects on a Delta Wing with Blown Jet

Julian Pabon
University of Dayton
Sidaard Gunasekaran
University of Dayton

Active flow control (AFC) devices can be utilized for stall mitigation, enhancing aerodynamic performance, and performing efficient maneuvers by altering the localized flow around different regions of a vehicle. A blown jet was installed along the upper surface of a flat plate delta wing half-span model with a 60° sweep angle in the University of Dayton Water Tunnel (UDWT). This study investigates the use of a blown jet to mitigate the breakdown of the leading-edge vortex. The mass flow rate and the corresponding momentum coefficient were controlled using a closed loop PI controller to alter the lift at various α using the actuator. Forces and moments were recorded to measure the performance. Static and dynamic tests were conducted to measure the change in behavior of vortex breakdown during quasi-steady and unsteady pitching at different moment coefficient. Measurable differences in lift coefficient are observed at a higher angle of attack with AFC. However, the impact of AFC diminishes with an increase in reduced frequency. Preliminary flow visualization revealed a bifurcation of the blown jet exit angle caused by the local pressure gradients at a range of angles of attack depending on the moment coefficient.

Abstract ID: 51DCASS-128

Cross-Stream PIV Characterization of the Prandtl-D3C Wake

Jessica Demoor
University of Dayton
Charles B. Cain
University of Dayton
Sidaard Gunasekaran
University of Dayton

This paper presents the cross-stream particle image velocimetry (PIV) measurements of the wake structure behind a Prandtl-D3C wing configuration tested in the University of Dayton Low-Speed Wind Tunnel. Previous computational and experimental efforts have suggested that bell-shaped lift distributions may suppress or delay tip vortex roll-up. However, direct experimental validation using cross-plane PIV has been lacking. In this study, PIV data were acquired at three downstream planes (2c, 3c, and 4c) under varying angles of attack and compared against FlightStream® panel method simulations. Results show a distinct inboard vorticity structure with no evidence of conventional wingtip vortex near the design condition, providing strong support for the hypothesized wake behavior. Background subtraction and multi-plane stitching were employed to resolve weak cross-stream velocity components. These findings contribute new experimental insight into the wake dynamics of non-elliptically loaded wings and support ongoing interest in low-vorticity, high-efficiency lifting surface designs.

Abstract ID: 51DCASS-137

Influence of Jet Pitch Angle and Pulse Frequency on Jet-in-Crossflow Flow Characteristics

Laura Senkar
University of Cincinnati
Daniel Cuppoletti
University of Cincinnati

The jet in crossflow is a well-studied phenomenon due to its relevance in a variety of aerospace applications, from film cooling to fuel injection. The canonical jet in crossflow is known to generate vortical structures in the flow field which vary with jet geometry and operating conditions. The present experimental study investigates the effects of varying jet pitch angle and pulsing frequency on total pressure differentials. Experiments were conducted in a subsonic wind tunnel with the jet flush with the wall and pulsed at a 50% duty cycle using a solenoid-controlled fluidic valve. High-speed total pressure measurements were recorded using Kulite pressure transducers to map planes of the flow field at multiple streamwise locations. These time-resolved measurements provide insight into both the total pressure losses induced by the jet as well as the fluctuations in total pressure generated due to the pulsing.

Abstract ID: 51DCASS-140

Experimental Investigations of a Dual-Mode Skin-Actuated- Camber with Embedded Twist (SACET) Morphing Wing

Julian Pabon
University of Dayton
Grace Schreyer
University of Dayton
Grace Selm
University of Dayton
Sidaard Gunasekaran
University of Dayton

A dual mode Skin Actuated Camber with Embedded Twist morphing wing is developed to approximate a bell-shaped lift distribution and the associated tip vortex free wake. Three morphing concepts are conceived for a rectangular wing using simple geometric models that link actuator motion to local rib twist. The concepts use independent servo driven ribs, a gear train that drives multiple ribs with a single shaft, and a linkage based single rod layout under a flexible skin. One configuration with embedded rib servos and TPU skin is fabricated and tested in the University of Dayton Low Speed Wind Tunnel and is compared with rigid wings that has the target twist and camber distributions. Measured lift, drag, and quarter chord moment coefficients show that the current prototype does not achieve the commanded twist, because the twist only morphing configuration behaves like the untwisted wing, while the rigid twisted wing exhibits the expected changes in lift, drag, and moment. The results indicate that higher twist authority and reduced skin resistance are required before the full aerodynamic benefits of dual mode morphing for bell shaped loading can be realized.

Abstract ID: 51DCASS-155

Quantum Hydrogen: H2 Probability Density and the Incompressible Navier-Stokes Solutions

Shaaban Abdhallah
University of Cincinnati
Ethan Leszczynski
University of Cincinnati

The analytical probability density solutions of the hydrogen (H2) wave equation are obtained from the numerical solutions of a new vortex-dipole formulation of the incompressible Navier-Stokes equations. Our hypothesis is supported by the numerical results that vortex-dipole strength, dipole orientation, and dipole configuration map to the hydrogen wave parameters (n, l, m) for a given Reynolds number. The impact of the proposed research is the potential of obtaining analytical solutions of the Navier-Stokes equations via the hydrogen probability density.

Heat Transfer & Thermal Management

Abstract ID: 51DCASS-009

Partially Catalytic Boundary Effects on Shock Boundary-Layer Interactions

Ariel Blanco
University of Dayton Research Institute
Nicholas J. Bisek
Air Force Research Laboratory

Time accurate CFD was used to quantify the differences in wall heating caused by fully-catalytic vs. noncatalytic boundary conditions for a double wedge at Mach 8.5 at free-stream conditions equivalent to an altitude of 35 km. It was observed that the integrated wall heating was appreciably higher for the fully catalytic wall model. This research explores the different partially catalytic wall models and their effect on Shock Boundary Layer Interactions in nonequilibrium, chemically reacting flows in terms of wall heating and other flow characteristics. Distribution Statement A: Approved for Public Release; Distribution is Unlimited; PA#AFRL-2025-2186.

Abstract ID: 51DCASS-011

Supersonic Film Cooling on a Flat Plate

Nicholas Medeiros
Air Force Institute of Technology
Marc D. Polanka
Air Force Institute of Technology
James L. Rutledge
Air Force Institute of Technology

High-temperature, supersonic flows are encountered in many modern aircraft propulsive systems such as Rotating Detonation Engines (RDE). These platforms require cooling to handle the high heat loads generated. Consequently, film cooling—a cooling method traditionally applied to combustorwalls and turbine surface components in subsonic flow—has gained interest as a viable technique in the supersonic flow regime. The Air Force Institute of Technology’s Small SupersonicWind Tunnel was modified to facilitate film cooling experimentation. Initially, a flat plate made out of Inconel 718 with five cylindrical holes spaced 5.. apart injected at 30 degrees was used for testing. Then, a flat plate made out of Ultem 100 with a single row of four cylindrical holes spaced 6.. apart was studied in a 1.77 freestream Mach number flow at ....s of 0.4, 0.8, 1.2, and 1.6. Schlieren imaging was used to understand the interaction of shock waves with the coolant holes.

Abstract ID: 51DCASS-016

Superposition of Unsteady Film Cooling Effectiveness Methods

Luke Wells
Air Force Institute of Technology
James L. Rutledge
Air Force Institute of Technology
Ethan A. Dean
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-029

Trajectory Scale Fluid-Thermal Analysis in the Gap Region of a High-Speed Control Surface

Jon A. Willems Jr.
Air Force Research Laboratory
Jack J. McNamara
The Ohio State University
Daniel A. Reasor Jr. and Thomas A. Mason
Air Force Research Laboratory
Christopher S. Weston and Carlos E. S. Cesnik
University of Michigan

A framework is developed to enable high-fidelity, component-level, coupled fluid–thermal simulations over mission-scale trajectories. The framework integrates a custom solver that couples computational fluid dynamics (CFD) with finite element thermal analysis, while interfacing with a reduced-order thermal model to provide trajectory-dependent boundary conditions. The approach is applied to the fin–body gap region of a high-speed all-movable control surface over the course of a trajectory segment, where varying incoming boundary layer characteristics are observed to shift gap-region flow structures with vehicle motion, driving movement of peak heating and temperature hot spots. Heating is amplified by up to 80 times relative to baseline conditions, with peak surface temperatures exceeding 2000 K. Additionally, two engineering level prediction strategies are constructed and compared to the higher fidelity coupled framework: one incorporating a single CFD solution and another neglecting CFD entirely. The former approach captures trends with root-mean-square errors remaining below 100 K in the thermal protection system and 10 K in the substructure, while the latter errors approach 500 K in the TPS components.

Abstract ID: 51DCASS-055

Exploring the Feasibility of an SMA Torque Tube Heat Pipe for Combined Thermal Transport and Mechanical Actuation

Liam Gallagher
University of Dayton
Rydge Mulford
University of Dayton

Equipment on NASA’s CubeSats has been known to fail early in the satellite lifetime due to poor thermal regulation. In pursuit of a robust solution to the problem of simultaneous passive thermal control and passive actuation, an SMA torque tube heat pipe was theorized. The focus of this research was to compare the many structural limitations that constrain the development of an SMA torque tube and the heat load limitations that constrain the development of a heat pipe. A code was developed in MATLAB which equates all relevant governing equations in order to determine valid tube geometries for a torque tube heat pipe made out of Nitinol, a popular shape memory alloy. Many varying parameters were examined to produce multiple outputs of valid geometries, thus providing design spaces that prove the feasibility of a Nitinol torque tube heat pipe.

Abstract ID: 51DCASS-051

Additively Manufactured Increasingly Porous Radiator For Static Thermal Management

Kristen Ess
University of Dayton
Rydge Mulford
University of Dayton

Effective thermal management is essential for spacecraft operating in the harsh and unpredictable space environment, where radiation is the main form of heat transfer. Radiators are commonly utilized to reject excess heat; however, many designs are limited by their fixed radiative properties and often require additional technology to meet mission requirements. This research proposes a novel passive, static spacecraft radiator based on an increasingly porous, additively manufactured structure designed to exploit the cavity effect to improve the radiative properties of the material. The proposed radiator transitions from a fully dense base, to an increasing porosity gradient that extends outward. Thermal radiation is transferred from the spacecraft into the radiator, where the pores act as spherical cavities that will reflect and absorb the radiation, thus increasing the emissivity and absorptivity of the material when compared to a fully dense structure. Additive manufacturing allows for porosity control through the laser’s energy density which allows for controllable porosity gradients. While porous materials have been extensively studied for mechanical and conductive thermal properties, their radiative properties, particularly in additively manufactured systems remain unstudied. By utilizing Monte Carlo ray tracing, an analytical model is being developed to predict the viability of this design, and the model has been verified using the view factor of a capped sphere. This work aims to experimentally characterize the emissivity and absorptivity of a porous additively manufactured material and assess its suitability for spacecraft thermal control. The anticipated outcome is a lightweight, robust radiator with high versatility and manufacturability, offering a simple and scalable alternative to conventional spacecraft thermal management systems.

Abstract ID: 51DCASS-064

Next-Generation Polymer Aerogel Insulation for Cryogenic Applications

Sadeq Malakooti
NASA Glenn Research Center
Stephanie L. Vivod, Wesley L. Johnson, Vadim Lvovich
NASA Glenn Research Center
Gitogo Churu, Jonathan Demko
LeTourneau University

The growing emphasis on next-generation aerospace technology utilizing on-board cryogenic fuels, including liquid hydrogen, has created an urgent need for advanced cryogenic insulation materials that do not currently exist. In response, NASA is supporting the development and implementation of next-generation polymer aerogel insulation materials for cryogenic fuel applications. Aerogels are exceptional thermal insulation materials suitable for both evacuated and non-evacuated environments. Polymer aerogels, in particular, offer thermal insulation performance comparable to other aerogel classes while providing enhanced structural integrity and toughness inherent to polymeric systems, attributes that are critical for cryogenic insulation. In this study, polymer aerogels with varying chemical compositions were developed and systematically investigated. Their thermal conductivities were measured across cryogenic temperature ranges and under different vacuum levels. Selected recent findings from this ongoing effort will be presented at this conference.

Abstract ID: 51DCASS-072

Development of a thermal solver to investigate phase change of atmospheric ice particles in hypersonic flows

Carlos Americo
University of Kentucky
Ethan H. Huff
University of Kentucky
Ahmed H. Yassin
University of Kentucky
Savio J. Poovathingal
University of Kentucky

One characteristic of the post-shock flow field surrounding a hypersonic vehicle is its high enthalpy, generated by compression as shock waves form. When an atmospheric ice particle is exposed to this environment, phase change processes can cause surface recession and partial mass loss. The short time scale thermal response and the irregular shapes of the ice particles require novel simulation approaches. An in-house solver has been developed based on the total enthalpy lattice Boltzmann method to quantify the melting process of ice particles.The thermal solver is verified by comparing numerical results with analytical solutions for three cases. The numerically obtained temperature profile for a sphere is compared with the analytical solution for multiple timestamps. The estimated total time to melt a sphere of ice is also investigated. The last case is the two-phase slab melting with an imposed high temperature at one face, where the different thermophysical properties for the two phases are considered. With the total enthalpy lattice Boltzmann solver verified, a milestone has been reached in the development of a fully coupled framework, in which the direct simulation Monte Carlo solver will compute the flow field in the region around the ice particle, providing the boundary conditions required by the thermal solver. The thermal solver will be integrated with a fully coupled thermal-fluid framework capable of handling dynamic phase change processes, aiming to assist in understanding potential damage to aerodynamic surfaces when hypersonic vehicles encounter a cloud of ice particles.

Abstract ID: 51DCASS-073

Heat Transfer Performance of Supercritical CO2 Under Variable Gravity

Jalen Reed
University of Dayton Research Institute
Andrew J. Schrader
University of Dayton
Jared R. McCoppin
University of Dayton Research Institute
Justin Delmar
Air Force Research Laboratory

This study investigates the influence of gravitational force on the heat-transfer behavior of supercritical carbon dioxide (sCO₂) in compact heat-exchange systems. Understanding sCO₂ performance under changing gravitational force (g-force) is essential for thermal management technologies designed for extreme or rapidly varying environments, where compactness, high efficiency, and robust operation are required. Although sCO₂ is widely recognized for its advantageous thermophysical properties, the effect of dynamic g-forces on its heat-transfer characteristics remains insufficiently understood. To address this gap, an experimental campaign was developed using a rotating platform to generate controlled g-forces on flowing sCO₂. A secondary objective of this work is to evaluate the reliability of mass-flow measurement devices exposed to dynamic g-forces, as accurate mass-flow determination is critical for heat-transfer correlations and system design. Preliminary experiments comparing a Coriolis mass-flow meter with a Cox turbine volumetric flow meter show that the Coriolis device maintains accurate mass-flow readings even under dynamic g-forces, indicating its suitability for dynamic g-force applications. The findings from this work will support improved modeling of sCO₂ thermal behavior and provide a foundation for extending these insights to sCO₂-based zeotropic mixtures and designing next-generation heat-transfer systems intended for high-load, extreme-environment operation. Preliminary results have already suggest significant deviations from established heat transfer correlations for sCO₂ under normal gravity, and as the full experimental matrix is completed, the resulting data will further clarify how gravitational effects influence buoyancy driven convective heat transfer, flow stability, and system performance in supercritical CO₂ and sCO₂-based zeotropic-mixture thermal management systems.

Abstract ID: 51DCASS-079

An Investigation into the Performance of a Conformal Heat Exchanger Compared to a Traditional Design

Nathan Lewan
Wright State University
Mitch Wolff
Wright State University

Advancements in aircraft systems and supporting equipment have resulted in high thermal loads within new generations of military aircraft without allocating the space requirements that would traditionally be needed for additional cooling. Heat exchangers are a thermal management system component used to transfer heat out of the aircraft and are often a challenge when it comes to balancing effectiveness realized and spatial requirements. Thus, it becomes imperative to study the relationship. This work presents a computational fluid dynamics (CFD) study over a conformal Triply Periodic Minimal Surface (TPMS) heat exchanger (HX) and compares the performance of the design to a baseline. Results show that when using the same surface area, hydraulic diameter, and shell design, the TPMS structure increased the Nusselt number nearly 70% and effectiveness 26% at maximum flow conditions. These gains were accompanied with a pressure drop increase from 0.79 psi for the traditional design to 5.26 psi for the conformal HX, representing the classic thermal-hydraulic tradeoff inherent in advanced heat exchanger geometries. Distribution Statement A: Approved for Public Release; Distribution is Unlimited. PA# AFRL-2026-0438

Abstract ID: 51DCASS-083

Compressibility Effects on Scaling Adiabatic Effectiveness

George Ip
Air Force Institute of Technology
James L. Rutledge
Air Force Institute of Technology
Connor J. Wiese
Air Force Institute of Technology
Marc D. Polanka
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-088

Generation of CFD Data for use by Physics-Informed Neural Network to Create Predictive Aeroheating Surrogate Model

Amy Cinnamon
Air Force Institute of Technology
José Camberos
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-092

Supercritical Energy Extraction Kinetics (SEEK) Turbopump Expansion Cycle Analysis

Liam Hackett
Wright State University
Mitch Wolff
Wright State University
Justin DelMar
Air Force Research Laboratory

Efficient thermal management is a critical challenge in compact, high-speed vehicles. One potential solution to this is using the system’s own fuel as a thermal sink. In this approach, the heated supercritical fuel is expanded through a turbine structure to power essential components, such as the fuel pump or for electrical power generation. Heating fuels far beyond the critical temperature instigates thermal cracking, which can improve the available heat sink capacity of the fuel; however, it also increases the risk for coking deposition. Coking in fuel lines has been a large focus of research to allow for increased duration of system operations, but the research has been primarily limited to coking in straight, statically heated tubes. This research project investigates the effects of expansion on coking deposition mechanisms within a turboexpander. This requires developing accurate equations of state (EOS) to simulate the non-ideal behaviors of supercritical fuel, followed by validation in a dedicated test rig. Successfully modeling these complex behaviors will maximize fuel heat sink potential, facilitating high-performance thermal management with minimal carbon deposition. Distribution Statement A. Approved for public release: distribution is unlimited. PA#: AFRL-2026-0448

Abstract ID: 51DCASS-095

Development of an Electrically Matching Boil-off Calorimeter for Thermophysical Property Measurement of CO2-Based Zeotropic Mixtures

Evan Fender
University of Dayton Research Institute
Justin Delmar
Air Force Research Laboratory
Jerod McCoppin
University of Dayton Research Institute

Supercritical CO₂ Brayton cycles have emerged as a promising technology for high-temperature power systems. To accommodate extreme environments, zeotropic mixtures are being explored for their ability to tailor thermodynamic properties to specific applications. While advanced fluid mixing models exist, there is limited experimental data regarding supercritical CO₂ mixtures that corroborates model data. This work addresses this gap by accurately measuring thermodynamic properties using an electrically matched boil-off calorimeter for the validation of REFPROP mixing models. Moreover, to ensure the accuracy of the calorimeter, two calibration runs were conducted using water and pure CO₂ as the test fluids. With these fluids, the calorimeter measurements were consistently found to be within 5% of the corresponding REFPROP values across the entire range of applied power. Initial results of a CO₂/R134a mixture having a molar ratio of 0.9/0.1 respectively found the difference in the REFPROP calculated power and experimental measurements to be within the total expanded uncertainty of the calorimeter and therefore are considered negligible. Further experimentation with a CO₂/R134a mixture having a molar ratio of 0.5/0.5 respectively is currently being conducted to confirm these findings and establish the model validity across the full range of molar ratios.

Abstract ID: 51DCASS-103

Development of Quality-Driven Control Framework for Two-Phase Flow Pump Loop

Colin Fokine
Wright State University

As aerospace systems trend toward more power-dense electronics, the ability to effectively manage these thermal loads has become increasingly important. Two-phase thermal management systems offer significant performance advantages compared to legacy systems, but are susceptible to flow instabilities under transient operating conditions. This work focuses on the control-oriented application of a refrigerant-quality sensor integrated into a two-phase pump loop. The two-phase flow of R-134a is driven by utilizing two direct-expansion cold plates connected in parallel. The primary objective is to assess the performance of the quality sensor across a range of operating conditions and identify the envelope in which reliable measurements are obtained. Validation will be conducted utilizing indirect quality measurements from system analysis and an ECT sensor connected upstream of the Quality Sensor. Following sensor validation, quality measurements will be incorporated into the development of feedback control strategies aimed at mitigating two-phase flow instabilities. The control algorithms, developed in LabVIEW, will be designed to regulate system operation based on real-time quality feedback. The goal is to demonstrate the feasibility of quality-based control to improve system stability and pave the pathway for reliable operation of two-phase thermal management systems in dynamic aerospace environments. Distribution Statement A. Approved for public release: distribution is unlimited. PA# AFRL-2026-0437

Abstract ID: 51DCASS-138

Heat Flux Characterization of Rotating Detonation Engine Configurations

Dylan Lawrence
University of Cincinnati
Ephraim Gutmark
University of Cincinnati

Rotating detonation engines (RDE) utilize detonation waves for pressure gain combustion and are a prospect for future advanced propulsion systems in both air breathing and rocket applications. Simulations of RDE show the potential to increase the pressure across the combustion chamber by 15-20 percent, and consequentially reduce fuel consumed by 4-9 percent, when analyzed in the context of use for commercial aviation [1]. In addition, RDE are significantly more compact than modern jet engines. Thermal management is one of the key challenges preventing aircraft integration of RDE. There are three different RDE configurations, annular, hollow, and flow through, and only one has been characterized through the lens of heat flux. Using embedded thermocouples and water-cooled combustor walls, the heat flux of each configuration can be empirically found and compared at various mass flows and equivalence ratios, for the first time. Through previous research conducted at the University of Cincinnati, the flow through configuration was identified to be the most promising for extended operation, suggesting that it could be a front runner for reducing heat flux through the combustor wall [2]. The greater characterization of heat flux for each configuration is expected to guide the future thermal design of RDE and the aircraft that they interface with. [1] Jones, S. M. and Paxson, D. E., “Potential Benefits to Commercial Propulsion Systems from Pressure Gain Combustion,” AIAA Paper 2013-3623, presented at the 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, San Jose, CA, July 14–17, 2013. [2] Anand, V. and Gutmark, E., “Rotating Detonation Combustor Research at the University of Cincinnati,” Flow, Turbulence and Combustion, Vol. 101, No. 3, 2018, pp. 869–893, doi:10.1007/s10494-018-9934-2.

Abstract ID: 51DCASS-139

Experimental Orthotropic Thermal Conductivity Measurements in FiberForm

James Senig
University of Kentucky
John F. Maddox
University of Kentucky

During reentry, hypersonic vehicles experience a range of extreme thermal environments during their descent due to aerodynamic heating Thermal protection systems (TPS) are designed to protect reentry vehicles from these high heat fluxes. Ablative insulation systems are a common choice for TPS when the vehicle is expected to experience high heat fluxes over short time periods, such as during reentry. These systems are typically composed of a porous, fiber matrix substrate impregnated with a chemically reactive resin. A common material used in ablative TPS is Phenolic-Impregnated Carbon Ablator (PICA). This work looks at characterizing the directional dependence of the thermal conductivity of the carbon fiber substrate used for PICA, FiberForm. The thermal conductivity of fibrous, porous materials is primarily a function of fiber matrix geometry, material, temperature, and pressure. Heat transfer through these materials is due to solid conduction, gaseous conduction, and radiation. Solid conduction takes place between neighboring fibers in the fiber matrix. Gaseous conduction occurs due to the gases present within the pores of the fiber matrix. Radiation is emitted, absorbed, and scattered by the individual fibers. The fiber orientation with respect to the incident heat flux determines how efficiently heat is transferred through the material. The in-plane thermal conductivity for FiberForm is estimated to be 2--3x higher than the through-the-thickness thermal conductivity.Understanding how heat is transferred in these materials is important for TPS design and optimization. An experimental apparatus has been developed that utilizes the comparative cut-bar method to measure the thermal conductivity of fibrous, porous insulation materials. Thermal conductivity measurements have been made for FiberForm in the in-plane and through-the-thickness directions over a range of temperatures. At an average sample temperature of 408.5 K, the in-plane and through-the-thickness effective thermal conductivities were 0.288 and 0.163 W/mK, respectively. At 515 K, the in-plane and through-the-thickness effective thermal conductivities increased to 0.315 and 0.178 W/mk, respectively. In both cases, the in-plane thermal conductivity of the FiberForm samples tested were 75-80% more conductive than the through-the-thickness samples.

Abstract ID: 51DCASS-145

Utilizing Liquified-Hydrocarbon and Liquid-H2 Fuels to Increase the Cooling-Capacity of Aerospace Platforms

Timothy Haugan
Air Force Research Laboratory
Chris J. Kovacs
Scintillating Solutions LLC
Leila Parsa
Scintillating Solutions LLC
Keith A. Corzine
Scintillating Solutions LLC
Saeid Saeidabadi
University of California, Santa Cruz

It is public knowledge that military air vehicles have an upper limit of thermal cooling capacity, from the limited volume capacity of fuel available which is the primary resource for a heat sink. And thermal bottlenecks continue to exist for years and are greatly limiting military missions – in some cases vehicles have to remain grounded for 20+ minutes to cool off. The problems of thermal-management-systems are summarized in a published article “Due to the massive leap in cooling and power needed to support post-2029 mission system upgrades, the existing Power-and-Thermal-Management-System will need to either be massively upgraded or replaced. There is widespread agreement that military vehicles are running too hot… Today’s vehicles are generating around 30 kilowatts. To compensate, today’s vehicles pull more high-pressure “bleed air” off its engine. That works, but it also puts more wear and tear on the engine, increasing maintenance costs over time. A recent GAO report found that “the limitations of the current cooling capacity could impede capabilities and mission systems as soon as 2029…. As a result, the new requirement is for 62 kilowatts of cooling capacity, and the government would like to reach or exceed 80 kilowatts” This presentation covers an option to utilize petroleum-based hydrocarbon or liquid-H2 fuels cooled to near their cryogenic liquid freezing points of 14 K to 135 K, to provide a > 4x increase of cooling capacity compared to JP8 being used as a heat sink. Hydrocarbon fuels studied include alkane compositions CxH2x+2 with x = 1-4; a.k.a. methane CH4, ethane C2H6, propane C3H8, butane C4H10 and mixtures of methane+ethane+propane and also liquid-H2. This is achieved without volume penalties usually associated with liquid cryofuels; e.g. ~ 18 % higher volume for liquid-natural-gas or liquid-methane. The large increase of cooling capacity comes from a 6-13x increase of delta-T and a 3-7x increase of specific heat, compared to JP8 jet fuel. Finally it is demonstrated that for a 1 MW aircraft, cooling capacities of ~ 100-120 kW can be achieved with either liquid-hydrocarbon or liquid-H2 fuels for exhaust temperatures of 300 K, which is ~ 4x higher than present public-known TMS limits ~ 30 kW for fighter jet aircraft. Ackowledgements: ARPA-E Subaward # 89703021SAR00022 for Contract # DE-AR0001355, AFOSR LRIR #24RQCOR004 and Dr. Ali Sayir, and the AFRL/RZ Aerospace Systems Directorate.

High School

Abstract ID: 51DCASS-124

Evaluating and Validating Auto-generated Knowledge Graph Accuracy

Isaiah Goble
Stebbins High School
Kara Combs
Air Force Research Laboratory

Given the popularity and increase in reliance on auto-generated data and graphs through artificial intelligence (AI), there is a trust placed in the accuracy of these graphs. IBM defines knowledge graphs to represent a network of real-world entities—such as objects, events, situations, or concepts—and illustrate the relationships between them. These graphs typically represent information and relationships in a machine-understandable way. We analyzed and compared human-curated graphs and auto-generated graphs using the Rattermann and Wharton dataset of short stories. The Rattermann dataset consists of sixteen problem sets consisting of five stories, denoted with letters A through E, with varying degrees of similarity to a sixth “base” story. The varying degrees of similarity come from different entities (subject(s) and object(s) within the story), first-order relationships (homogenous relationships between entities), and higher-order relationships (homogenous relationships between relationships (of any order) and/or heterogeneous relationships between an entity and another relationship (of any order)). The Wharton dataset is fairly similar; however, it contained 14 sets twice each with three stories and a base. The stories are A1, B1, A2, B2, with A1 and A2 being nearly identical aside from entities, and the same with B1 and B2. A1 is the base in Wharton-A, and B1 is the base in Wharton-B. Our knowledge graphs were identifying the relationships within each story and visualizing them. Our graphs consisted of two-part nodes and edges. Each node was an entity in the story, and the edges were the relationships that connected them to other nodes. Higher-order relationships were marked with edges, but they were between two edges. We did two sets of human-curated graphs. The extractive set contained relationships word for word that are in the stories, which is the baseline we compared the auto-generated results to. There was also the Abstractive dataset, which contained the relationships identified in the extractive set but also relationships we humans can infer from the text. The abstractive is the goal we would like to see reached but also the human standard. The evaluation standard we used was via graph edit distance. Graph edit distance is the number of edits needed to transfer one graph to another. Edits were marked as insertion of new edges or nodes, deletion of edges or nodes, and substitution, which is the changing of a label of a node or edge. Results were, on average, requiring around twenty-five edits to transform the auto-generated into the extractive. Future work could include testing more auto-generating tools, using different datasets to evaluate, or testing different evaluation metrics.

Abstract ID: 51DCASS-149

Differentiating Lithium-6 and Lithium-7 Isotope Contents Using Seven Spectral Lines from Laser Induced Breakdown Spectroscopy

Roscoe Schumann
Global Impact STEM Academy
Anil Patnaik
Air Force Institute of Technology
Travis Morris
Air Force Institute of Technology

Awaiting public release.

Imaging & Diagnostics

Abstract ID: 51DCASS-097

Trace Lithium Isotope Analysis of the 2s-2p Doublets via Surface-Enhanced Nanosecond LIBS

Travis Morris
Air Force Institute of Technology
Anil Patnaik
Air Force Institute of Technology

Laser-Induced Breakdown Spectroscopy (LIBS) provides a promising alternative approach for rapid analysis of lithium isotopes. Broadening and self-reversal effects in LIBS have traditionally restricted the ability for experimental measurements to spectrally resolve fine structure emission characteristics. Using surface-enhanced LIBS in combination with trace lithium analysis, reductions in combined broadening effects and elimination of self-reversal were observed. Experimental measurements confirm isotopic discriminations of lithium fine structure emission features with single-shot nano-second LIBS under atmospheric conditions.

Machine Learning

Abstract ID: 51DCASS-019

Design of Reinforcement Learning Curriculum for Helicopter Autorotation Control Agent

Matthew Thompson
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-043

Implicit Realizability Enforcement in Machine Learning-assisted Turbulence Modeling

James Wnek
Wright State University
Mitch Wolff
Wright State University
Christopher Schrock
Air Force Research Laboratory
Eric Wolf
Ohio Aerospace Institute

Realizability, or the requirement of non-negative turbulent kinetic energy, has traditionally been difficult to enforce in the major class of tensor basis models, exemplified by the tensor basis neural network (TBNN). The current state of the art is realizability-informed training, which uses a penalty term to explicitly train the model to enforce realizability, but penalty methods are known to have ill-conditioning problems and limited effectiveness outside the training domain. Here, we propose a novel realizable tensor basis neural network (RTBNN) architecture that implicitly enforces realizability. A comparison is made to the baseline TBNN and realizability-informed training. The results show that the RTBNN exactly enforces realizability with improved generalization compared to the TBNN, and 30% less training time compared to realizability-informed training. This research provides a foundation for further development of tensor basis models in machine learning-assisted turbulence modeling. Distribution Statement A: Approved for Public Release; Distribution is Unlimited. PA# AFRL-2026-0390

Abstract ID: 51DCASS-093

Neural Network-Based Adaptive Control Gain Adjustment for IntroSAT

Chun-kai Yang
University of Cincinnati
Daegyun Choi
University of Cincinnati
Donghoon Kim
University of Cincinnati

Conventional control strategies, such as proportional-integral-derivative or linear quadratic regulator controllers, are widely used for various systems. However, such methods with fixed control gains may not be suitable for systems that require high precision. Furthermore, these approaches often cannot handle critical real-world factors, such as friction, motor performance variability, sensor latency, and structural vibration, which can degrade system stability. To address these limitations, this work proposes an adaptive controller that incorporates a neural network (NN) into the control architecture of IntroSAT, a tabletop CubeSat platform equipped with three reaction wheels. Using inputs, such as the system’s attitude angle, reaction wheelrotational speed, and other relevant sensor data, the NN model dynamically determines incremental adjustments to the controller gains. This adaptive mechanism enhances the robustness of the attitude control system under uncertain and time-varying conditions.

Abstract ID: 51DCASS-098

Analysis of Deep Neural Network Architecture for High Dimensional Non-Linear Spaces

Mark Bergman
Wright State University
Harok Bae
Wright State University
Karen Demille
Air Force Research Laboratory

This study investigates the characteristics of optimal deep neural network (DNN) architectures trained on multi-fidelity datasets for modeling complex, nonlinear, and high-dimensional system responses under sparse data conditions typical of aerospace vehicle design exploration. Rather than relying solely on automated architecture generation methods such as Bayesian or evolutionary search, this work systematically examines how key hyperparameters, including the number of hidden layers, total neuron count, and neuron density across layers, govern model behavior during and after training. Architectural performance is characterized using three primary metrics: loss and validation trend analysis, statistical behavior of ensemble weight and bias distributions, and high-resolution validation across the input domain. By analyzing the emergence of consistent statistical patterns in trained networks and their relationship to predictive performance, this study provides insight into how structural design choices influence learning dynamics and generalization, offering guidance for informed neural network architecture selection in multi-fidelity aerospace modeling applications.

Abstract ID: 51DCASS-108

Characterization and Confidence-based Adaptive Machine Learning for Conceptual Aerospace Vehicle Design

Ethan Cawley
Air Force Institute of Technology
Timothy Massie
Wright State University
Harok Bae
Wright State University
José A. Camberos
Air Force Institute of Technology
Ramana V. Grandhi
Air Force Institute of Technology

We propose a new machine learning modeling approach to quantify the prediction confidence of a trained model and adaptively select the best training parameters during active learning. By monitoring and analyzing the data early in the learning process, one can enhance the efficiency of an ensemble modeling framework using an emulator-embedded neural network for high-dimensional design-space exploration. Two primary mechanisms enhance modeling efficiency: Integrating sub-models of important variables as emulators to accelerate model training and adaptively configuring the algorithm to best fit the problem. Adaptive samples, emulators, architecture size, and hyperparameters work together to effectively capture complex modeling problems. The ensemble model provides prediction bounds that reflect the uncertainty arising from the aggregated variables, fostering informed decision-making. In this paper, a practical problem of conceptual aerospace vehicle design and a high-dimensional analytical example demonstrate the effectiveness of the proposed approach.

Abstract ID: 51DCASS-134

Multi-Fidelity Machine Learning for Aerodynamic Field Response Prediction with Uncertainty Quantification

Joseph Osborn
Wright State University
Harok Bae
Wright State University
Carlos Suarez
Air Force Research Laboratory
José A. Camberos
Air Force Institute of Technology

This project presents a novel approach to multi-fidelity machine learning to efficiently predict full-field aerodynamic responses and their credibility for an advanced aerospace vehicle. By converting complex computational fluid dynamics mesh data into a 1-D form through a space-filling curve, the method enables the use of a convolutional autoencoder to reduce data dimensionality. An embedded neural network then combines low- and high-fidelity simulation data to reconstruct surface flow fields efficiently and accurately. The core effort of this work is to develop a new technical capability of estimating the confidence bounds of the field response prediction by implementing a machine learning ensemble approach. Demonstrated on a blunted cone with fins using data from an aerodynamic modeling and simulation tool, the proposed approach significantly reduces computational costs while providing accurate predictions and confidence bounds of the predictions, a task that is challenging with traditional surrogate modeling approaches due to high computational costs.

Abstract ID: 51DCASS-152

Light-Curve Simulation Datasets for Rocket-Body Characterization

Elijah Lewis
Cedarville University
Doxa Kudari
Cedarville University
George Landon
Cedarville University

Earth orbit is increasingly crowded, and Space Domain Awareness (SDA) requires timely characterization of resident space objects, including rocket bodies. Approximately 44,870 space objects are routinely tracked by global space surveillance networks. Of these, an estimated 1,576 are classified as rocket bodies. These rocket bodies typically measure between 2 and 4 meters in diameter and range from approximately 5 to 15 meters in length. Many ground-based observations are unresolved, with the object spanning only a few pixels; the primary measurement is an optical light curve (apparent brightness versus time) rather than detailed shape imagery. This project builds a simple, interactive light-curve generator for rocket bodies in orbit and a supporting dataset of photometrically consistent rocket-body geometry. The tool combines observation geometry (line-of-sight, illumination, and range), a rocket-body mesh, and an attitude/rotation model to generate simulated apparent magnitude time series for user-selected scenarios. A secondary mode featuring a user interface with simple controls alongside the rendered simulation allows operators to gain intuition for how to produce data using the software. A reproducible analysis pipeline reduces optical photometry into calibrated light curves, estimates periods, and extracts descriptive features for comparison with simulations. To facilitate this effort, the project aims to compile a robust dataset, pairing 3D mesh approximations for a subset of common rocket bodies with corresponding time-series flux and rotational data, enabling repeatable evaluation across multiple workflows. The geometry dataset pairs publicly available imagery with mesh generation and refinement using generative models, followed by normalization for consistent rendering and evaluation. Model generation consists of choosing quality images of rocket bodies or launch vehicles from the public internet and passing one or more as input to a generative model specialized in output of 3D meshes and textured material, closely matching the rocket body in the image. The combined 3D mesh and photometric material dataset combined with an interactive light-curve simulator provide a practical workflow for unresolved optical analysis of rocket bodies. This enables simulation-to-observation comparisons that support RSO characterization tasks in SDA, including rotation-state estimation, geometry screening, and consistency checks against cataloged objects.

Materials & Structures

Abstract ID: 51DCASS-024

Advancements in carbon conductors for extreme aerospace environments

John Bulmer
Air Force Research Laboratory
Kadyn Tackett, Charlie Ebbing, Brice Hall, Jake Blue, Sabrina Eddy
Air Force Research Laboratory
Mary-Ann Sebastian, Chris Kovacs, Tom Bullard, Timothy J. Haugan
Air Force Research Laboratory

The upper aerospace environment is exceedingly demanding, characterized by extreme temperature swings, oxidative and extreme ultraviolet radiation, and high-radiation plasma conditions, where material performance is frequently the limiting factor in system capability. Advanced materials with multifunctional properties are required to operate reliably across a wide parameter space. Carbon nanotube (CNT) cables are an emerging, strategically important aerospace-enabling material, combining high electrical conductivity (2.2–10.9 MS m⁻¹, exceeding copper on a specific-weight basis) with exceptional tensile strength (4.2–14 GPa, rivaling carbon fiber). Further improvements are anticipated through increased CNT molecular length and chemically ordered dopants. In this sense, CNT conductors represent a mechanically resilient, bendable analog of graphitic intercalation compounds (GICs)—brittle, doped derivatives of graphite that can exceed copper’s room-temperature conductivity by up to 50%. In this talk, we present electrical transport studies of CNT conductors with systematically controlled doping levels and molecular aspect ratios, measured over an exceptionally broad envelope (temperatures from 65 mK to 2373 K and magnetic fields up to 60 T) with the following observations: 1) At extreme high temperatures, achieved via direct current injection, CNT conductors exhibit metallic-like conduction up to 2373 K, with specific conductivity comparable to graphite, tungsten, and molybdenum. Notably, the CNT ribbon maintains mechanical flexibility and resilience during and after graphitization heat exposure; this demonstrates superior practical current-carrying capability above 1500 K and particular relevance to high-temperature aerospace environments such as plasma electrodes. 2) At millikelvin temperatures, the resistance saturates to a finite value, demonstrating the intrinsically metallic nature of the CNT assembly and its potential to directly compete with conventional aerospace electrical wiring. Magneto-transport measurements reveal a complex magnetic-field response, including positive longitudinal magnetoresistance exceeding 22% near room temperature. Analysis indicates two dominant contributions: classical two-band magnetoresistance and Aharonov–Bohm–like corrections associated with curvature-induced bandgaps. These effects have implications for CNT conductor performance in magnetic environments such as light-weight motors, generators, and electromechanical machines. 3) Finally, we report progress in incorporating networks of aligned fullerene supramolecular crystals within CNT fibers. Following alkali-metal doping, magnetization and transport measurements indicate the emergence of a robust superconducting phase within a mechanically resilient architecture. This result points toward a new paradigm for CNT cables: all-carbon coated conductors that combine electrical stability, mechanical strength, and flexibility unmatched by traditional superconductors. Such conductors may enable lightweight, high- strength superconducting magnets for aerospace systems, supporting aerospace-centered power- density energy storage and magneto-hydrodynamically enabled virtual flight control surfaces.

Abstract ID: 51DCASS-031

Fatigue Behavior of an Advanced C/SiC Composite with a [0/90/±45] Layup at Elevated Temperature

Hassan Khokhar
Air Force Institute of Technology

High-temperature tension–tension fatigue behavior of a carbon fiber–reinforced silicon carbide (C/SiC) ceramic matrix composite was investigated. The composite was reinforced with T300 carbon fibers, and the laminate architecture consisted of 32 plies of plain-weave fabric arranged in a quasi-isotropic (0/90/±45)s layup. The composite was fabricated using chemical vapor infiltration (CVI) of silicon carbide into the carbon fiber preform. Prior to CVI processing, the fiber preforms were coated with pyrolytic carbon and an anti-oxidation coating to promote a weak fiber–matrix interphase. Monotonic tensile behavior of the C/SiC composite was characterized and the tensile properties were measured at 1200 °C. Tension–tension fatigue behavior was evaluated at 1200 °C in laboratory air. Fatigue tests were conducted at a stress ratio of R = 0.1 and a loading frequency of 1 Hz, with applied fatigue stresses ranging from 29 to 96 MPa. Fatigue runout was defined as 200,000 cycles. Specimens that achieved runout were subsequently subjected to monotonic tensile testing at 1200 °C to evaluate retained tensile strength. Pre- and post-test composite microstructure was examined to elucidate damage and failure mechanisms. Fractographic analysis revealed significant degradation of the carbon fibers, indicating that oxidation-driven fiber deterioration played a dominant role in the damage accumulation and ultimate failure of the C/SiC composite at 1200 °C in air. 

Abstract ID: 51DCASS-035

Design and Optimization of Spherical and Cylindrical Void-Based 3d Phononic Metamaterials for Wide Elastic Bandgap and Enhanced Mechanical Properties.

Md Aniruddah Alam
Miami University
Mehdi Zanjani
Miami University
Muhammad Jahan
Miami University

Awaiting public release.

Abstract ID: 51DCASS-037

A permeability model for stochastic modeling of heat shields

Donghyun Kim
University of Kentucky
Ayan Banerjee
University of Kentucky
Luis Chacon
University of Kentucky
Savio J. Poovathingal
University of Kentucky

Thermal protection system (TPS) plays a crucial role in protecting hypersonic vehicles against extreme heat load during entry conditions. In order to design effective TPS, a thorough understanding of fundamentals of how the TPS material reacts to its aerothermal environment is necessary. Existing methods to simulate the vehicle entry suffer from high uncertainty caused by the material stochasticity, and current material response solvers require flow properties established across a broad range of structural length scales and porosities. To address these challenges, an empirical semi-parametric model is developed. This model takes in rarefied flow simulation data, validated against experimental results, and outputs distributions of principal permeability for any arbitrary set of length scale and porosity of the material. Generated model distributions show good agreement with the simulation data, providing a promising way for supplying material response solvers and entry system modeling frameworks with the parameters needed for improved TPS design.

Abstract ID: 51DCASS-039

Tensile and Fatigue Behavior of an Advanced Quasi-isotropic C/SiC Composite at 1200⁰C in Air

Nicholas Garbinski
Air Force Institute of Technology
Marina Ruggles-Wrenn
Air Force Institute of Technology

The tensile and fatigue properties of a quasi-isotropic C/SiC composite were investigated at 1200⁰C in laboratory air. The composite was reinforced with T300 carbon fibers. Laminated carbon fiber preforms consisted of 24 plies of plain weave fabric in a 0/±60 layup. Carbon fiber fabric was heat treated at 3000°F and coated with micron-scale pyrolytic carbon to create a weak fiber-matrix interface. The composite was processed by chemical vapor infiltration (CVI) of SiC into the carbon fiber preform. Tensile tests were performed at 1200°C in laboratory air to assess the tensile stress-strain response and measure tensile properties. Tension-tension fatigue behavior was studied at 1200°C in laboratory air. Tension-tension fatigue tests were performed with a frequency of 1 Hz, a minimum to maximum stress ratio (R) of 0.1 and fatigue stresses ranging from 27 MPa (15 %UTS) to 134 MPa (73 %UTS). Fatigue run-out was defined as survival of 200,000 cycles. Composite produced short cyclic lives, exhibiting poor fatigue durability. Fatigue run-out was not achieved even at a low fatigue stress of 27 MPa (15 %UTS). Pre- and post-test composite microstructure was examined using optical and scanning electron microscopy. Pre-test microstructural examination revealed extensive matrix microcracking and porosity in the as-processed material, which likely contributed to premature fatigue failures. Examination of the fracture surfaces showed evidence of extreme oxidative degradation of the carbon fibers. In all fatigue specimens the fibers on the perimeter of the fracture surface were completely destroyed by oxidation, creating a “picture frame” effect. In many cases, the fibers were absent (i. e. fully destroyed by oxidation) over the entire fracture surface. The findings of this effort indicate that this material is not suitable for long-term structural applications at elevated temperatures in air.

Abstract ID: 51DCASS-045

Assessing Damping Effectiveness with an Additively Manufactured Internal Powder Pocket Design

Madelyn Pratt
Air Force Research Laboratory
Dino Celli
Air Force Research Laboratory
Tommy George
Air Force Research Laboratory
John Brewer
Air Force Institute of Technology

In the aerospace community and, specifically within gas turbine engines, designing to prevent fatigue remains as a primary requirement for current and next generation Air Force vehicles. A recently emerging embedded powder damping technology combined with additive manufacturing (AM) has been demonstrated to significantly improve vibration suppression of research articles and components. However, a phenomenon referred to as “lock-up”, has been observed when the research article and damping exceed a vibratory threshold leading to a permanent loss in damping performance. To explore the issue of lock-up, Zirconia and Inconel powders are embedded in Aluminum cassettes with varying powder volumes and installed on a modular beam. The damping effectiveness of each cassette with internal powder pockets are then evaluated with a 6K electrodynamic shaker and the results reported. It is expected that by increasing the operational threshold to prevent lock-up utilizing this damping technology in fielded components will lead to an increase in longevity of aircraft parts and improve structural stability by reducing vibrations experienced during operation. Distribution Statement A: Approved for Public Release; Distribution is Unlimited. PA# AFRL-2026-0191

Abstract ID: 51DCASS-061

Mechanical and Interface Properties of Cu and Low-Dimensional Carbon Nanocomposites

Abigail Eaton
AFIT Contractor
Arun Nair
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-062

Oxidation and Mechanical Properties of Low Dimensional Materials

Ebin Thomas
Air Force Institute of Technology
Arun Nair
Air Force Institute of Technology
Abigail Eaton
AFIT Contractor

Awaiting public release.

Abstract ID: 51DCASS-063

Deformation Behavior of Composites Under Impact Loading

Aidan McCarley
Air Force Institute of Technology
Arun Nair
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-068

Size-Weight-and-Power Analysis of Magnetic Systems for Aerospace Magnetohydrodynamic Power Generation

Chris Kovacs
Scintillating Solutions LLC
Levi Elston
Air Force Research Laboratory
John Bulmer
National Research Council
Timothy Haugan
Air Force Research Laboratory

Awaiting public release.

Abstract ID: 51DCASS-084

Characterizing and Modeling the Resin-Fiber Interaction of PICA Using FIB-SEM

Shreya Pokharel
University of Kentucky
Luis Chacon, Savio Poovathingal, Ph.D
University of Kentucky

Awaiting public release.

Abstract ID: 51DCASS-104

Toward Substrates with Embedded Strain Isolation: Property Design Space Exploration of a 3D-Printable Self-Healing Elastomer

Max Drexler
University of Dayton
Adin Stoller, Alex Watson, Robert Lowe
University of Dayton
Allyson Cox
University of Dayton Research Institute

Soft robotic and stretchable electronic systems require damage-resistant substrates capable of large elastic deformations and robust electrical component integration without failure from the resulting mechanical compliance mismatch. Self-healing elastomers (SHEs), which offer autonomous repair and extended device lifetimes, are promising candidates for addressing these needs. In parallel, advances in additive manufacturing have enabled digital light processing (DLP) 3D-printable SHEs with complex geometries suitable for soft electronic system integration. This work navigates the property design space of a novel thiol-acrylate, 3D-printable SHE for the development of a tunable substrate suitable for stretchable electronic applications. Design space boundaries are utilized to develop substrates that leverage soft-hard modular healing and functional grading in order to solve the “compliance-mismatch problem” in soft electronic material systems. Using commercial off-the-shelf precursors and a commercial DLP 3D printer (Figure 4 Modular, 3D Systems), a library of SHE formulations was developed through systematically varying the thiol-to-diacrylate ratio. ASTM D412 Type C samples were used to characterize each formulation’s mechanical and autonomous self-healing properties through both quasi-static uniaxial tensile testing and Shore 00 hardness testing. The investigation produced a broad design space demonstrating hard-to-soft elastomeric behavior within a single material system. Additional thiol content appears to result in a reduction of total UTS, with an increase in portion recovered after self-healing. Variation of thiol content allows for a large selection of possible fracture strains, useful for creating strain-isolating structures. Adjusting thiol content allows for the large variation of material hardness, supporting the creation of substrates suitable for soft-hard modular configurations. The investigated design space establishes the material system as a versatile, scalable platform for the creation of complex, soft-hard modular architectures, providing a foundation for integration into self-healing stretchable electronic systems.

Abstract ID: 51DCASS-113

Characterizing the Combined Axial-Torsion Response of Additively Manufactured Polymers in Varied Print Orientations

Stephen Richter
AFIT Contractor
John Brewer
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-118

Additively Manufactured Conformal Triply Periodic Minimal Surface Heat Exchanger Design and Evaluation

Tanner Barber
Air Force Institute of Technology
John Brewer
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-148

Integrating Lightweight Structures and FEA for Validating Novel Composite Materials & Architectures

Tahseen Al-wattar
Central State University
Mohammadreza Hadizadeh
Central State University

This research introduces an integrated framework that advances the role of additive manufacturing from a prototyping tool to a powerful experimental platform for material innovation and model validation. The main idea lies in combining multi-platform 3D printing technologies, including fused deposition modeling (FDM), vat photopolymerization (VP), stereolithography (SLA), and powder-based methods with computational modeling such as Finite Element Analysis (FEA) and Artificial Neural Network (ANN) to both design and validate novel composite materials under realistic boundary conditions. This approach demonstrates that complex boundary and loading conditions typically confined to simulations can be physically realized through advanced 3D printing, enabling direct experimental validation. Initially, body centered cubic (BCC) lattice structures were designed using SolidWorks, 3D printed via fused deposition modeling (FDM) and experimentally tested under compression to validate FEM and artificial neural network (ANN) predictions. Building on this, hierarchical Inside BCC unit cells, combining cubic shells with internal lattices, were fabricated to study the effects of vertical and horizontal struts on mechanical responses , demonstrating strong correlation between experiments and FEA simulations . More recently, glass microfiber-reinforced high-temperature polymers were 3D-printed using vat photopolymerization (VP), with tensile testing and scanning electron microscopy confirming the influence of fiber content and post-curing on mechanical performance. We plan to extend this framework to create composite material, which is polymer high temp resin, micropowder of boron nitride (BN), and milled glass fiber to explore as thermally conductive, electrically insulating interfaces for semiconductor devices. Across all phases, complex boundary and loading conditions traditionally applied in FEA models have been physically realized using advanced 3D manufacturing, enabling direct experimental validation. This integrated approach accelerates design cycles, enhances predictive accuracy, and demonstrates the versatility of advanced 3D manufacturing as a powerful research tool for fabricating and testing novel composite materials, bridging computational models with real-world applications.

Abstract ID: 51DCASS-150

Pressure limitations based on wall thickness of a TPMS lattice structure

Kathleen Spangler
Air Force Institute of Technology
John Brewer
Air Force Institute of Technology
Tanner Barber
Air Force Institute of Technology
Zachary Garner
Air Force Research Laboratory
Abdeel Roman
Air Force Research Laboratory

Awaiting public release.

Abstract ID: 51DCASS-156

Oxidation and Mechanical Properties of Low Dimensional Materials

Ebin Thomas
Air Force Institute of Technology

Carbyne is a 1-Dimensional chain of carbons that is on the order of the atomic scale in width. Carbyne has a high modulus of elasticity and thermal conductivity. However, carbyne can be hard to produce experimentally and its properties vary with temperature. This brings forth a need to computationally analyze carbyne at simulated conditions. The analysis will be based on ReaxFF potentials implemented by LAMMPS, with a focus on oxidation effects. The test that will be performed is a limited representative of re-entry conditions that would affect Carbyne chains, and a Graphene layer placed over a substrate.

Model-Based Systems Engineering

Abstract ID: 51DCASS-086

Hypersonic Research Aircraft Modeling and Simulation with ADAPT

John Halus
Air Force Institute of Technology
José Camberos
Air Force Institute of Technology

Awaiting public release.

Orbital Mechanics

Abstract ID: 51DCASS-096

Mapping Quasi-Chaotic Lunar Transport Pathways in the Earth-Moon CR3BP

Jeremiah Specht
Air Force Institute of Technology
Robert Bettinger
Air Force Institute of Technology
Rachel Oliver
Air Force Institute of Technology
Bruce Cox
Air Force Institute of Technology

The Circular Restricted Three-Body Problem (CR3BP) is a simple but powerful model to describe and investigate trajectories within the Earth-Moon system. Leveraging a Poincaré map with the CR3BP is a useful method to define periodic, quasi-periodic, and quasi-chaotic trajectories. While most research focuses on periodic and quasi-periodic orbits, these typically remain around a single body or equilibrium point. This research focuses on the quasi-chaotic regions of the Poincaré map to explore trajectories that transfer to the lunar region. This research uses a Jacobi constant of 3.175 to ensure that Lagrange Point 1 (L1) is open to allow access to the Moon and Lagrange Point 2 (L2) is closed to keep trajectories inside the system. The focus of this research is the discovery and exploration of dynamical structures within the quasi-chaotic region defining trajectories that transfer from the Earth to the Moon. Exploring this dynamic structure exposes a framework to explain and map out the quasi-chaotic region. Mapping the quasi-chaotic region builds understanding in this previously unexplored area enhancing trajectory planning and prediction for cislunar objects. Knowledge of how all classes of trajectories, even those in the quasi-chaotic regions, evolve over time is essential for space situational awareness (SSA) and mission planning as the amount of cislunar objects grow.

Abstract ID: 51DCASS-106

Non-Planar Multipass Aerobraking Around the Earth and Mars

Colin Pate
Air Force Institute of Technology
Robert Bettinger
Air Force Institute of Technology
Kerry Hicks
Air Force Institute of Technology

Awaiting public release.

Abstract ID: 51DCASS-151

Retrospective 3-Degree-Of-Freedom Performance Evaluation of Boeing X-20 Dyna-Soar

Jinhee Byun
Air Force Institute of Technology
Robert Bettinger
Air Force Institute of Technology
Kerry Hicks
Air Force Institute of Technology

The X-20 Dyna-Soar program of the late 1950s and early 1960s represented one of the earliest systematic efforts to develop a piloted hypersonic lifting vehicle capable of controlled atmospheric re-entry following near-orbital flight. A central reference case used throughout the program was the “once-around mission", in which the vehicle was boosted to near-orbital velocity from Cape Canaveral, completed approximately one orbit around the Earth, and executed an unpowered hypersonic glide to a conventional landing at Edwards Air Force Base. Although trajectory analysis for this mission was published during the original program, it was performed using computational tools and modeling assumptions characteristic of the era. This study presents a modern numerical reconstruction of this mission using contemporary MATLAB-based simulation techniques. The simulation is initialized at the documented end-of-boost condition and propagates the subsequent unpowered hypersonic glide and atmospheric descent. Aerodynamic coefficients, lift-to-drag characteristics, and mission parameters are taken directly from original Dyna-Soar documentation, with emphasis on reproducing the altitude vs. downrange trajectory reported by Lesko as the primary validation benchmark. In addition to longitudinal trajectory fidelity, the reconstructed flight path is evaluated against the lateral maneuverability constraints reported for the Dyna-Soar by comparing the simulated cross-range displacement to the cross-range corridor described by Hargis. Agreement with both the altitude-to-range evolution and the cross-range envelope demonstrates that the essential equilibrium flight, energy management, and maneuverability characteristics attributed to the Dyna-Soar mission can be independently replicated using modern computational methods.

Space Systems

Abstract ID: 51DCASS-038

Numerical Modeling of a Heat Shield for Rocket Cargo

Dylan Viveros
Air Force Institute of Technology

Rocket Cargo enables rapid, global payload delivery but presents significant challenges during Earth reentry due to extreme aerodynamic heating encountered at hypersonic speeds. This research develops and applies a computational heat-transfer modeling tool to identify preliminary thermal protection system solutions tailored to Rocket Cargo reentry trajectories. The primary objectives are to maintain acceptable internal payload temperatures while minimizing both the cost and areal mass of the heat shield. Transient heat conduction within a multi-layer thermal protection system is approximated using numerical finite difference methods in one- and two-dimensional models to evaluate the thermal response under time-varying reentry heating conditions.

Abstract ID: 51DCASS-041

Aerodynamic Modeling of a VLEO Satellite

Tristan Martin
University of Kentucky
Savio Poovathingal
University of Kentucky

Deploying satellites in Very Low Earth Orbit (VLEO, less than 450km above the surface of the Earth) offers several advantages, such as reduced latency for communication applications and more accurate data for Earth observation. However, the relatively high density of gas in this region subjects satellites to significant aerodynamic drag. If left unopposed, this drag force causes the satellite to undergo orbital decay and eventually unintended atmospheric re-entry. The primary method to counter the drag force is electric propulsion, which relies on an accurate characterization of the aerodynamic forces acting on the satellite. This study aims to accurately model the aerodynamic forces experienced by the CISM satellite developed by the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. Using the Direct Simulation Monte Carlo (DSMC) method with the Cercignani–Lampis–Lord (CLL) gas-surface interaction model, simulations were run, systematically varying the CLL accommodation coefficients. This study contributes to improving aerodynamic modeling for VLEO applications to reduce reliance on physical testing.

Abstract ID: 51DCASS-050

An ISRU-Based Lunar Architecture for Monthly Lunar Sample Returns

Clark Zhang
University of Michigan
Marloes van de Zwart
University of Michigan
Adrien Boissy
University of Michigan
Rabhya Gupta
University of Michigan
Jeremy Glende
University of Michigan

This presentation describes a mission concept for a lunar-manufactured sample-return architecture capable of delivering 100 kgs of payload from the lunar south-polar region to Earth on a monthly cadence. The closed-loop in-situ resource utilization (ISRU) workflow includes excavating lunar regolith, refining structural alloys, collecting propellants, and producing lunar payloads on a power budget of 400 kilowatts. The launch vehicle is primarily manufactured and integrated on the lunar surface, with specialty components (like avionics) shipped to the Moon. Subsystem-level designs for the launch vehicle structures, power, propulsion, thermal management, communications, data handling, and attitude control support a 4-day mission lifetime from lunar surface launch to splashdown on Earth. This mission expands upon the Artemis program, which aims to establish a sustainable, long-term human presence on the Moon for the purposes of more advanced in-situ research in preparation for future crewed missions to Mars. Studies have shown that the Moon has significant deposits of valuable Helium-3. A key mission objective is to deliver helium isotopes for terrestrial scientific and technological applications. Unlike traditional mission architectures that require launching a spacecraft from Earth, landing on the lunar surface, and returning with the payload, the proposed approach builds the launch vehicle on the moon. This reduces launch costs and eliminates complex lunar landing operations, enabling a more resource-efficient method for transporting Helium-3 to Earth. The mission builds from the Foundational Surface Habitat and other infrastructure to be established on the lunar surface during the Artemis missions. A key mission enabler is a 400 kilowatts nuclear reactor and regenerative heat cycles, permitting the use of high Technology Readiness Level (TRL) excavation and processing technologies capable of manufacturing sufficient structural materials and rocket fuel for launch, which consists of lunar ascent, trans-Earth injection, a single-skip atmospheric reentry, and parachute-assisted splashdown for payload recovery. The vehicle maintains continuous communication with lunar ground stations during ascent, and earth ground stations during atmospheric re-entry and splashdown, while operating autonomously during trans-Earth cruise phase. The concept couples regolith excavation, beneficiation, molten-regolith electrolysis, and inductive refining into a vertically integrated ISRU pipeline. Over 95% of the return vehicle mass uses ISRU-derived materials: structural aluminum alloys, a regolith-based ablative heat shield, powdered-aluminum and liquid oxygen rocket motor, and hydrogen peroxide reaction control thrusters. Through phased development, this mission demonstrates that a closed-loop ISRU workflow spanning resource extraction, materials processing, vehicle fabrication, propellant production, and launch operation can yield a repeatable, robust sample-return capability without continuous Earth-based logistical support.

Abstract ID: 51DCASS-052

Compensating Disturbance to the Base Spacecraft using the Second Arm for a Dual-Arm Space Robotic System

James Talavage
University of Cincinnati
Andrew Barth
University of Cincinnati
Ou Ma
University of Cincinnati

Earth’s orbits are becoming increasingly cluttered with defunct satellites and other man-made debris that were not placed on decaying trajectories or removed, thereby raising the risk of collisions with functional satellites. With the advancement of the In-space Service, Assembly and Manufacturing (ISAM) technologies this issue can be addressed, and fewer satellites can be sent into orbit, rather existing satellites can be serviced. Even with remote or automated satellite servicing becoming viable, one factor that needs to be attended is the capability of stabilizing or balancing a servicing satellite’s attitude during an ISAM mission, so that it can perform safe and smooth robotic operations. To address these challenges, a robotic control strategy, called Dual-Arm Zero Momentum (DAZM), which minimizes the attitude disturbance to base spacecraft of a dual-arm servicing system by properly maneuvering one arm while the other arm is performing a required service operation. Simulation-based study demonstrates the effectiveness of the DAZM method for stabilization of the base spacecraft. Further directions for developing and maturing this method are also explored.

Abstract ID: 51DCASS-053

Impact of Very Low Earth Orbit (VLEO) Environment on Multi-Surface Satellite Drag

Aleksei Shaverin
University of Kentucky
Ahilan Appar
University of Kentucky
Savio J Poovathingal
University of Kentucky

Very Low Earth Orbit (VLEO) satellites offer advantages such as increased resolution, reduced orbital debris collision risk, lower radiation exposure, and faster communication, albeit at the expense of significantly increased atmospheric drag. Unlike high-altitude satellites, drag plays a dominant role in satellite performance in VLEO. Due to the rarefied nature of the VLEO environment, traditional Computational Fluid Dynamics (CFD) approaches fall short in accurately representing gas–surface interactions. Previous studies by Jiang et al. 1have demonstrated the reliability of Direct Simulation Monte Carlo (DSMC) by comparison with analytical expressions for flow over simple geometries under similar conditions. Building on these simple geometries, the present work examines Multi-Material configurations and geometry-induced multi-collision behavior relevant to realistic spacecraft surfaces. While specular reflections yield predictable aerodynamic trends, diffuse and physically realistic collision models are substantially more complex and computationally expensive. To mitigate this, we develop and validate an analytical model that accepts flow parameters and geometric inputs to predict the mean reflection direction while accounting for multiple surface collisions. This framework enables direct calculation of drag and lift coefficients for complex, Multi-Material surfaces, preserves consistency with classical free-molecular limits for simple geometries, and provides a fast and transparent alternative to full DSMC simulations. Furthermore, a material-dependent gas–surface interaction model is developed and utilized to improve the accuracy of the predicted aerodynamic response 2. Conventional DSMC surface models typically rely on idealized specular or diffuse reflection assumptions with accommodation parameters that are only weakly correlated with actual surface material properties. As a result, variations in surface composition, surface geometry, and their combined effects on scattering behavior are not explicitly captured. Together, the proposed analytical framework and material-dependent gas–surface interaction model enable efficient, physically grounded prediction of aerodynamic forces for complex Multi-Material spacecraft in the VLEO regime. ACKNOWLEDGEMENTS [1] Jiang, Y. et al. (2022) ‘Aerodynamic drag analysis and reduction strategy for satellites in very low Earth orbit’, Aerospace Science and Technology, 132, p. 108077. doi:10.1016/j.ast.2022.108077. [2] Appar, A. and Poovathingal, S.J. (2026) ‘Gas–surface interaction model for very low Earth orbit (VLEO) systems’, Aerospace Science and Technology, 170, p. 111550. https://doi.org/10.1016/j.ast.2025.111550.

Abstract ID: 51DCASS-056

LEOPARDSat-1: Preliminary Lessons from a Student-Led CubeSat Project

Matthew Verbryke
University of Cincinnati
Samuel Kohls
University of Cincinnati
Nathan Nguyen
University of Cincinnati
Michael Carovillano
University of Cincinnati
Donghoon Kim
University of Cincinnati

CubeCats is a student-led engineering organization at the University of Cincinnati (UC) whose mission is to provide hands-on experience in space systems engineering through the design, development, and operation of nanosatellites. The Low Earth Orbit Platform for Aerospace Research Development Satellite 1 (LEOPARDSat-1) is a 1U CubeSat mission investigating the use of carbon-composite materials for radiation shielding in Low Earth Orbit. Originally selected by the NASA CubeSat Launch Initiative in 2018, LEOPARDSat-1 is scheduled for launch to the International Space Station on the CRS NG-24 mission for on-orbit deployment in mid-2026. In addition to being the first space mission for both CubeCats and UC, LEOPARDSat-1 is notable for its programmatic structure, as the project has been executed and managed almost entirely by students, with faculty serving primarily in an advisory role. This presentation provides an overview of the project’s origin, mission objectives, system design, and development history, with particular emphasis on the technical, organizational, and continuity challenges encountered over an extended, multi-year development timeline. The lessons learned from LEOPARDSat-1, including those related to systems engineering practices, project management, documentation, and external coordination, are currently informing subsequent CubeCats missions, and are expected to be broadly applicable to other institutions seeking to establish or sustain similar student-led CubeSat programs.

Abstract ID: 51DCASS-060

Conceptual Design of a Low-Cost Dual-Satellite Communication Network for the Cislunar Region

Matias Ramirez Cisternas
Air Force Institute of Technology
Rachel M. Derbis
Air Force Institute of Technology

The advancement of sustained lunar exploration has underscored the need for continuous, autonomous communication systems in the cislunar environment. This work introduces the preliminary design of a low-cost, dual-satellite architecture that enables reliable data relay without persistent dependence on Earth-based infrastructure. The system leverages intersatellite links (ISL) between two CubeSat-class spacecraft in Earth-Moon L2 halo orbits, with store-and-forward capabilities supporting asynchronous communication with lunar surface assets during Earth occultation periods. Preliminary analysis includes orbital geometry, link budget performance, and subsystem-level trade-offs to assess feasibility under CubeSat constraints. The concept aims to extend surface and orbital communication coverage, offering a scalable and resilient relay solution for future science and exploration missions within the Earth-Moon system.

Abstract ID: 51DCASS-078

Separable Cislunar Nanosat Mechanism for On-Orbit Dynamic Reconfiguration Section: Space Systems

John Spann
Air Force Institute of Technology
Rachel M. Derbis
Air Force Institute of Technology
John S. Brewer
Air Force Institute of Technology

With cislunar space becoming a dedicated global focus for research and Space Situational Awareness (SSA), nanosatellite deployment in the region presents a unique opportunity to support emerging operational needs. In partnership with NASA’s Artemis program to extend human presence beyond the International Space Station (ISS) to cislunar and interplanetary destinations, the United States Space Force (USSF) continues to expand its sphere of influence beyond cislunar with an increased importance on dynamic spacecraft operations well outside traditional Earth-centric orbits. This research presents a design for a 12U CubeSat to be deployed from a NASA Artemis mission following its translunar injection burn, propagate through the Circular Restricted Three-Body Problem (CR3BP) and Bicircular Restricted Four-Body Problem (BCR4BP), insert into a periodic or quasi-periodic southern L2 halo orbit, and then separate into two independent 6U CubeSats. Once established, the independent 6Us will perform Linked, Autonomous, Interplanetary Satellite Orbit Navigation (LiAISON) to determine orbits using satellite-to-satellite tracking (SST) in cislunar space. In support of SST and space traffic management (STM) objectives, the coupled 6Us will house the Mirror Illumination for Reconnaissance and Rendezvous of Orbital Resident Systems (MIRRORS) payload. Using reflected sunlight to illuminate and track dimly lit orbital resident systems. The study addresses two distinct mission areas: a mechanical separation mechanism and an orbit design. Building on Artemis launch loading requirements for Rocket Lab canisterized satellite dispensers (CSD), the mechanical separation mechanism must enable the coupled 12U CubeSat to withstand launch loads within its dispenser, minimize modifications to the standard 6U design, and provide controlled, low-relative-velocity separation at the appropriate time. Designed within the clearance provided for a 12U CSD, the separation mechanism’s design will be vibroacoustically examined to determine the best design for launch survival. Simultaneously, the orbital trajectory design leverages n-patch point differential correction, low-thrust arcs, lunar gravity assists (LGA), stable manifold connections, and Poincare mapping to dissipate the substantial energy imparted in the translunar injection burn from the Artemis Space Launch System. With an infinite number of permutations in cislunar trajectories, the results provide a comparison of trajectory options, staging orbits, and total delta-v in order to determine the feasibility of transfers within CubeSat-class propulsion constraints. Each focus of the research feeds into the requirements for the whole system and establishes a foundation for dynamic reconfiguration of nanosatellites in cislunar space. Ultimately, the research contributes to the broader objectives of enabling reconfigurable small satellite systems, improving on-orbit SSA tools, and supporting secure and sustained operations in a region of growing strategic importance.

Abstract ID: 51DCASS-105

Reaction Wheel-Equipped 3-DOF Air-Bearing Testbed for Zero-Speed Crossing Analysis

Ilyas Malik
University of Cincinnati
Rajat Chadha
University of Cincinnati
Ozair Kissana
University of Cincinnati
Daegyun Choi
University of Cincinnati
Donghoon Kim
University of Cincinnati

Reaction Wheels (RWs) are widely used for attitude control in a wide range of satellites due to their high resolution and low jitter characteristics. Although RWs are typically operated around a nominal speed (e.g., half the maximum speed) to allow for momentum changes in both directions, zero-speed crossings (ZSCs) are often unavoidable and critical for mission success. However, these ZSCs introduce severe nonlinear effects, including Coulomb and viscous friction, Stribeck phenomena, and stiction, which can lead to peak current spikes. These events may increase thermal stress, accelerate bearing wear, and reduce overall RW lifespan. This work presents a RW-equipped three degrees-of-freedom air-bearing testbed with a 3U CubeSat size to investigate the ZSC effect and its impact on peak current magnitudes, occurrence frequency, and target-speed tracking. The focus is to develop and calibrate the testbed along with preliminary tests to create a foundational platform for future research on RW control strategies and their influence on RW performance and lifespan.

Abstract ID: 51DCASS-114

Experimental Validation of Dynamic Coupling Effects Using the Reconfigurable Space Manipulator Testbed

Rajat Chadha
University of Cincinnati
Daegyun Choi
University of Cincinnati
Donghoon Kim
University of Cincinnati
Gargi Das
University of Cincinnati
Diego Quevedo
University of Cincinnati

As the scope of on-orbit servicing, assembly, and manufacturing expands, the reliance on autonomous Space Manipulator Systems (SMS) becomes increasingly critical. A fundamental challenge in deploying free-floating SMS is the phenomenon of dynamic coupling, where the motion of the robotic manipulator exerts reaction forces and torques on the base spacecraft, resulting in unintended disturbances that compromise mission precision. While theoretical models of these interactions exist, experimental validation in a relevant microgravity environment remains a gap in current research. This work addresses this gap by using a high-fidelity, planar air-bearing testbed designed to emulate the dynamics of a free-floating SMS. This work presents a comprehensive analysis of the dynamic coupling effects using a testbed that equips two reconfigurable 3-degrees-of-freedom robotic arms on the floating base. By systematically varying kinematic parameters, such as link lengths and masses and initial joint configurations, the dynamic coupling effect caused by the manipulator is experimentally confirmed, and the experimental results are compared with the analytical coupling models. This study will provide crucial experimental data to inform the design of future SMSs as well as guidance, navigation, and control architectures for next-generation space servicing missions.

Abstract ID: 51DCASS-132

Impedance Control Model Identification For A Free-Flying Space Robot Manipulating A CubeSat

Diego Quevedo
University of Cincinnati
Donghoon Kim
University of Cincinnati

Awaiting public release.

Turbomachinery & Propulsion

Abstract ID: 51DCASS-014

Effects of Duct Aspect Ratio on Shock Train Behaviors

Jack Sullivan
The Ohio State University
Datta V. Gaitonde
The Ohio State University

The effects of rectangular duct aspect ratio on the mean and unsteady behavior of a shock train interaction are explored using high-fidelity simulations. Three aspect ratios (AR) are considered, spanning the set AR=w:h={0.82, 1.00, 1.20}. To isolate the effects of geometric length scales, all other parameters and setup decisions are identical across the three simulations, with inflow Mach number, duct Reynolds number, interaction back-pressure, wall temperature, and inflow boundary layer thicknesses fixed for all cases. Effects on the time-mean structure and unsteady dynamics of the shock trains are analyzed in depth, with particular attention paid to the three-dimensional variations of the shock wave/turbulent boundary layer interactions that comprise the systems, which manifest as statistical variations between the lateral walls, vertical walls, and corner junctions of the ducts. Variations in the time-mean turbulent statistics are also noted, with each duct displaying unique turbulence amplification and recovery behaviors in the near-wall shear layers. As a final thrust, scaling laws and self-similarity parameters for these mean and unsteady properties of the shock trains are constructed, using length, time, and velocity scales that by definition account for the intrinsic three-dimensionality and pressure histories present in the developing duct flows. Use of the developed scaling paradigm effectively collapses multiple observed mean and unsteady features across the considered aspect ratios, including relative duct confinement, shock cell spacing, and the tones that result from shock column undulation.

Abstract ID: 51DCASS-028

Effect of Cross-Sectional Shape on Shock Train Behaviors

Nathanael Wendel
The Ohio State University
Datta V. Gaitonde
The Ohio State University
Stuart I. Benton
Air Force Research Laboratory

Direct comparisons are made between square and circular cross-sectional shaped supersonic ducts to study the shock train differences. By maintaining a measure of equivalence between the ducts, such as channel half-height versus radius, and boundary layer displacement thickness for analogous core flows, Reynolds number, Mach number, and back pressure, one to one comparison is achieved. Mean flow features are compared with respect to the number of shocks, the spacing, and shape of each shock in light of corner boundary layer separation. The presence of corner flow separation is also explored by comparing effects elsewhere, such as pressure recovery and flow symmetry/distortion. Turbulent statistical quantities and amplification are also analyzed and compared between cases. In particular, the corner bisectors of the square case are compared with the mid-wall planes, as well as with the circular walls for an assessment of turbulence evolution along the length of the ducts. PA# AFRL-2026-0266

Abstract ID: 51DCASS-069

Investigating Buoyancy Effects in Unsteady Rim Seal Structure Formation

Evan Sears
The Ohio State University
Randall M. Mathison
The Ohio State University

Unsteady rim seal structures (URSS) that form in the cavity between rotating and stationary airfoils significantly alter the flow field in a turbine stage. They drive ingress and egress of hot gas into the rim seal and can impact both the turbine stage’s efficiency and the thermal loading on the blade platform and rotor. URSS formation has primarily been attributed to Kelvin-Helmholtz instabilities between shearing main gas path and cooling flows. However, these studies show large discrepancies in structure count and rotor-relative speed depending on the type of study. Low-temperature fundamental studies show more, faster-rotating structures, while high-temperature engine-representative studies find fewer, slower-rotating structures. This suggests buoyancy is a major factor in URSS formation. Buoyancy-driven Rayleigh-Benard convection cells are shown to behave similarly to URSS in somewhat-analogous compressor drum flows, further supporting this theory. Short-duration experiments have been performed on an industrial turbine stage in two separate builds. High-speed time-accurate pressure measurements in the rim seals of these experiments have shown a consistent once-per-revolution pressure drop. This pressure drop is amplified when both main gas path and cooling flows are present, suggesting that the measurements are capturing the transient development of the URSS. The present work attempts to demonstrate the similarity of Rayleigh-Benard convection cell development to URSS development seen in experiments through unsteady RANS simulations for a simplified geometry. To date, the work has demonstrated how Rayleigh-Benard cells develop in the compressor cavity, matching the steady-state conditions of previous rotating cavity experiments and revealing a pressure distortion that rotates with the forming Rayleigh-Benard cell.

Abstract ID: 51DCASS-082

Experimental validation of a thermodynamic cycle model for a micro-class turbojet engine

Noah Segerstrom
Cedarville University
Dustin Luna
Cedarville University
Joseph D. Miller
Cedarville University
Zhaohui (Geroge) Qin
Cedarville University

Thermodynamic cycle analysis models are widely used to predict the performance of aerospace propulsion systems; however, because of their reliance on configuration-specific efficiency parameters, accuracy is dependent on experimental testing for validation and refinement. Experimental testing and predictive performance analysis were conducted on a JetCat P100-RX micro-class turbojet engine provided through the Aerospace Propulsion Outreach Program (APOP). Tests were designed and executed to measure or record turbomachinery and propulsion performance parameters, including thrust, shaft RPM, and fuel mass flow rate over a range of engine speeds. The thermodynamic cycle model includes component efficiency and compressible flow considerations in addition to calculation of measurable performance parameters. Stages of the model, corresponding to specific engine components, were validated using manufacturer provided data, analytical calculations, and experimental data to ensure acceptable assumptions and accuracy throughout development. The model predicts experimental thrust data with an accuracy better than 4% collected over engine speeds of 30–100%.

Abstract ID: 51DCASS-159

Adaptive Control Volume Model for Predicting Pseudoshock Outlet Properties

Loren Hahn
National Research Council
Andrew Oliva
University of Notre Dame
Aleksandar Jemcov
University of Notre Dame
Sergey Leonov
University of Notre Dame
Scott Morris
University of Notre Dame

An adaptive control volume (CV) model is developed to predict pseudoshock outlet quantities as a function of backpressure for supersonic internal flows. The model accounts for outlet Mach number nonuniformity using two primary independent variables and can be formulated under either attached or separated flow assumptions. The model is applied to a Mach 2 pseudoshock in a rectangular duct with area change and is validated against CFD solutions. Results demonstrate accurate prediction of the area-averaged Mach number and mass-averaged total pressure over a wide range of backpressures. Sensitivity analyses show that the solution is weakly dependent on the nonuniformity parameter once sufficiently large, while the turbulent momentum transport parameter strongly influences total pressure losses. Beyond validation, the adaptive CV model provides physical insight into pseudoshock physics, enables rapid design iteration, permits reliable prediction of outlet quantities using only wall static pressure measurements, and offers potential for low-cost, real-time system monitoring and control in high-speed vehicle applications.