Papers and Reports

This paper presents a high-fidelity aeropropulsive assessment of the SUSAN Electrofan's distributed electric propulsion (DEP) and boundary layer ingestion (BLI) aft fuselage turbofan technologies. This is achieved through the application of computational tools for aerodyanmic and aeropropulsive design and analysis based on the Reynolds-averaged Navier-Stokes (RANS) equations.
High-Fidelity Aeropropulsive Assessment of Distributed Electric Propulsion and Boundary Layer Ingestion for the SUSAN Electrofan AIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

Hybrid- and all-electric aircraft concepts use electric motors for power rather than a conventional jet engine. Electric propulsors open the door to new ways to synergistically integrate the propulsion system with the airframe. For example, many small electric propulsors can be distributed along the wing to increase the effective bypass ratio for better overall efficiency. Furthermore, these propulsors can be attached to the wing surface for boundary layer ingestion (BLI) to further the efficiency gains.
High-Fidelity Aeropropulsive Optimization of a Mail-Slot Distributed Electric Propulsion System for the SUSAN ElectrofanAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

A multidisciplinary design optimization methodology to directly minimize the ground-level noise generated by the sonic boom of a high altitude supersonic body is presented. A Cartesian Euler flow solver is coupled with an atmospheric propagation tool to create a ground-noise analysis capability for supersonic bodies.
Sonic Boom Ground Noise Minimization via the Adjoint Method AIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

Wall-modeled large-eddy simulation (LES) of a swept wing with leading-edge ice buildup is performed using three mesh paradigms and associated flow solvers and compared to experimental results. The study focuses on an 8.9% scale model of the CRM65 swept wing featuring both high-fidelity and smooth leading-edge ice shapes. The assessment is conducted using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) framework using the three actively supported meshing paradigms in LAVA: structured curvilinear overset, unstructured, and Cartesian.
Wall-Modeled LES of a Swept Wing With Leading-Edge Ice Using LAVA Curvilinear, Unstructured, and Cartesian SolversAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

This paper establishes a method to create surface pressure databases that allow for uncertainty quantification. Aerodynamic databases are critical products for launch vehicles and other aeronautical systems, and surface pressure databases are one such database that constains large quantities of data. The focus of this work is the relationship between the integrated force and moment database and the surface pressure database.
Copula-Based Method to Generate Consistent Surface Pressures Under UncertaintyAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

Wall-Modeled Large Eddy Simulation (WMLES) studies for the 5th AIAA High-Lift Prediction Workshop (HLPW5), conducted using the Launch Ascent and Vehicle Aerodynamics (LAVA) unstructured solver, are presented. The numerical methods, modeling approaches, and meshing strategies are described. A subset of the results for workshop cases 2 and 3 is discussed, with comparisons to available experimental data and insights gained through grid sensitivity studies.
LAVA WMLES Results for the 5th High-Lift Prediction WorkshopAIAA SciTech 2025 Forum, Orlando, FL, January 6-10, 2025.

A scoping study is being conducted on the air supply for a microjet-based active flow control (AFC) system on a twin-turbofan commercial transport airplane. Microjets provide circulation control using small surface-normal pneumatic jets located near the trailing edge of a lifting surface such as a wing or flap. In this study, microjets are considered for installation in the flaps of the high-lift version of the Common Research Model (CRM-HL).
Scoping of an Air Supply Configuration for Active Flow Control on a Commercial Transport Airplane High-Lift System34th Congress of the International Council of the Aeronautical Sciences (ICAS), Florence, Italy,

Solar activity is a primary factor determining the state of the Earth’s space environment, geomagnetic and ionospheric disturbances, and radiation hazards. In the current state of knowledge, machine learning (ML) methods provide essential tools for processing data, investigating relationships among various physical properties and characteristics, uncovering hidden connections, and predicting hazardous solar events. To facilitate ML-ready data preparation and access, we have developed an interactive database of solar flares integrating the most essential datasets.
Development of Solar Flare and Energetic Particle Prediction PortalXXXII IAU General Assembly, Cape Town, South Africa, August 6-15, 2024.

Ingenuity has sustained an astonishing 72 flights on Mars. The little helicopter proved that non-terrestrial powered flight is possible, even on planets with thin atmospheres. Future planetary rotorcraft will be bigger and heavier to accomplish new scientific and exploratory goals. This work evaluates the effectiveness of existing numerical simulation models in predicting the severity of this phenomenon for planetary rotorcraft.
Comparing Planetary Helicopter Brownout Observations With Numerical Predictions for IngenuityAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

A physics-based moving-body unsteady Reynolds Averaged Navier-Stokes based method for predicting the onset of transonic buffet is described. Four test cases of varying complexity are chosen to evaluate the approach; an ONERA OAT15A supercritical airfoil, a NACA0012 airfoil, the NASA High-Speed Common Research Model, and the Boeing SUGAR Phase V Transonic Truss Braced Wing.
Evaluation of a Physics-Based Unsteady RANS Method for Buffet Onset PredictionAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

The unstructured Voronoi mesher currently being developed within the Launch, Ascent, and Vehicle Aerodynamicssoftware framework at NASA Ames Research Center is described in detail. The discussions include, but are not limited to, the strategies used in the seeding and smoothing phases to ensure a high-quality mesh for Wall-Modeled Large-Eddy Simulations, the methods behind the cell clipping algorithm responsible for conforming the mesh to a complex geometry, and the approach to create a global mesh from the distinct Voronoi cells.
LAVA Voronoi Mesher for Wall-Modeled Large-Eddy SimulationsAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

This paper presents an investigation into the potential benefits of a boundary layer ingestion aft fuselage propulsion system, or tail-cone thruster, when applied to two transport category aircraft: a conventional tube-and-wing configuration based on the NASA Common Research Model and a transonic truss-braced wing configuration.
Aeropropulsive Assessment of a BLI Tail-Cone Thruster Propulsion System for the NASA Common Research Model and a Transonic Truss-Braced Wing ConfigurationAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

The CFD solver OVERFLOW was used to simulate the CobraMRV undergoing supersonic retropropulsion (SRP) in the Langley Unitary Plan Wind Tunnel as part of a CFD and wind-tunnel integration effort. Selection of numerical methods and resulting comparisons to selected tunnel conditions of interest are detailed.
Comparison of OVERFLOW Computational and Experimental Results of the CobraMRV Mars Entry Vehicle Concept During Supersonic RetropropulsionAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

Simulations of unsteady supersonic retropropulsion flow over a Hypersonic Inflatable Aerodynamic Decelerator blunt-body vehicle were performed using the OVERFLOW Computational Fluid Dynamics solver. High-fidelity flow solver techniques, including Detached Eddy Simulation turbulence modeling and Adaptive Mesh Refinement, were employed to obtain improved realism in CFD predictions.
Comparison of OVERFLOW Computational and Experimental Results for a Blunt Mars Entry Vehicle Concept During Supersonic RetropropulsionAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

Traditional Reynolds-averaged Navier-Stokes grid methods applied to aerodynamic shape optimization can struggle with the deformation of surface and volume grids at component intersections, such as at wing-fuselage junctions. To overcome this, we propose an approach which utilizes curvilinear overset grids for the discretization of the domain, with the presence of the body modeled using an immersed boundary method.
Towards Aerodynamic Shape Optimization Using an Immersed Boundary Overset Grid MethodAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

The goal of this work is to quantify uncertainty in the level of noise reaching the ground from supersonic aircraft at cruise conditions. To cope with uncertainty in the state of the atmosphere, the temperature and relative humidity profiles are parameterized using a Karhunen-Loeve expansion based on a novel formulation involving dew point temperature.
Acoustic Signature Uncertainty Quantification for Quiet Supersonic AircraftAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

Fluid-structure interaction simulations have the potential to accelerate the certification process of parachute systems for interplanetary robotic exploration missions while helping to mitigate risks by covering a wider range of scenarios than can be flight tested. The Launch, Ascent, and Vehicle Aerodynamics team is working toward actualizing this potential by further developing the capability to perform such fluid-structure interaction simulations and validating it with the best supersonic parachute flight test data available.
Fluid-Structure Interaction Simulations Of Supersonic Parachute Inflation: Model SensitivitiesAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

A series of scale-resolving simulations of flow over the ONERA OAT15A airfoil have been performed at an angle of attack of 3.5 degrees, just past the onset of buffet. The focus of this study is to document the sensitivity of the wall-modeled large eddy simulation methodology for curvilinear structured overset grids within the Launch, Ascent, and Vehicle Aerodynamics framework to mesh spacing, mesh distribution, and domain size.
Wall-Modeled Large Eddy Simulations of Transonic Buffet Over a Supercritical AirfoilAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

The development of innovative open-rotor propulsion systems that meet performance, fuel efficiency, and noise standards for commercial use depends significantly on the availability of reliable and computationally efficient tools for aerodynamic performance and noise prediction. This investigation demonstrates the capability of the structured curvilinear overset grid Computational Fluid Dynamics solver within the Launch, Ascent, and Vehicle Aerodynamics framework to predict the aerodynamic and aeroacoustic characteristics of a Contra-Rotating Open Rotor propulsion system under various sideslip angles.
Exploring the Impact of Sideslip Angle on Acoustic Predictions of an Open Rotor System Using Scale-Resolving SimulationsAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

We investigate the utility of adjoint-based error estimates for sonic boom farfield simulations governed by solutions of the augmented Burgers' equation. Solution of this nonlinear system uses operator splitting with a second-order finite volume discretization in space and second-order Runge-Kutta time marching, while the absorption and molecular relaxation are solved using second-order central differencing.
Discretization Error Estimation and Control for Farfield Acoustic SignaturesAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

Automation of overset structured surface mesh generation has recently been accomplished by the creation of face, edge, and node meshes based on Boundary Representation solids as the geometry input. The current work continues the automation effort in overset volume mesh generation and domain connectivity based on the auto-generated surface meshes.
Advances in Automation of Overset Structured Volume Mesh Generation and Domain ConnectivityAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

The effects of laminar-to-turbulent transition modeling in the Spalart-Allmaras and Langtry-Menter’s shear stress transport turbulence models are explored through high-fidelity simulations of the XV-15 rotor in hover. Using NASA’s OVERFLOW solver, solutions on grids of varying resolutions with a range of collective angle configurations are compared alongside experimental data.
Effect of Transition Modeling on the XV-15 Hovering Rotor FlowsAIAA Aviation Forum and Ascend 2024, Las Vegas, NV, July 29-August 2, 2024.

A detailed analysis of transonic aerodynamics of a pitching conceptual Boeing Truss-Braced Wing (TBW) section has been carried out at various Mach numbers at a typical reduced frequency, k = 0.15. A new important flow feature of hysteresis loop cross-over has been discovered through the analysis of the hysteresis loops.
Machine Learning of Unsteady Transonic Aerodynamics of a Pitching Truss-Braced Wing SectionAerospace Science and Technology, vol. 152, September 2024.