![]() Our campaign of six scale-resolving simulations was completed in roughly five weeks. Francois Cadieux, NASA Ames Research Center Results and Impact With further code optimization and numerical method improvements, the turnaround time and overall computational cost could be reduced by half, making this methodology potentially usable in the later stages of the engineering design cycle. The goal was to demonstrate that accurate and reliable CFD predictions can be obtained for time-averaged drag on the vehicle (discounting the thrust generated by its eight SRP rocket motors) using relatively modest computing resources in a short-enough turnaround time to potentially affect future engineering design decisions for the vehicle. ![]() We also performed a grid convergence study for the most dynamic case (Mach 2.4) with four different mesh resolutions. The Launch Ascent and Vehicle Aerodynamics (LAVA) team at Ames, drawing from recent successes with Orion launch abort simulations, used the LAVA Cartesian solver to simulate the concept vehicle at three different trajectory points with over-expanded plumes, where previous CFD results showed the most disagreement (Mach 2.4, 2.52, and 2.78). The goal of our work was to conduct scale-resolving simulations of a conceptual Mars EDL vehicle using SRP, leveraging the agency’s high-performance computing resources at the NASA Advanced Supercomputing (NAS) facility at NASA’s Ames Research Center. There is an urgent need to develop new best practices so that CFD can be relied upon to design EDL systems, including these difficult trajectory points, and thus reduce the need for comparatively costly wind tunnel tests. These interactions occur over a wide range of scales from immediately upstream of the nozzles to several vehicle diameters upstream-significantly increasing the cost of CFD simulations. Typical CFD approaches struggle at points along the Mars EDL trajectory where the SRP motor plumes are over-expanded (due to high altitude and Mach number) because of the chaotic and dynamic interactions between the turbulent plumes and the bow shock. Accurate and reliable computational fluid dynamics (CFD) predictions are needed to help design future Mars EDL concepts with SRP technology as an alternative to the high cost and limitations of wind tunnel tests. ![]() SRP concepts do away with supersonic parachutes and instead use the thrust from rocket motors pointed in the direction of travel to decelerate. Previous Mars entry, descent, and landing (EDL) systems made use of a bluff body capsule to decelerate the vehicle to roughly twice the speed of sound, and then deployed parachutes to further decelerate to a safe landing velocity. Supersonic retropropulsion (SRP) is a deceleration technology that could enable larger payloads-and potentially, humans-to safely land on the surface of Mars. ![]()
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