Scale-Resolving Simulations of a Supersonic Retro-Propulsion Concept for Mars Entry, Descent, and Landing

Speaker: François Cadieux, Computational Aerosciences Branch, NASA Ames Research Center
February 3, 2022

Presentation

Abstract

Supersonic retro-propulsion (SRP) is a deceleration technology that could enable larger payloads and potentially humans to be brought from space to the surface of Mars safely. Accurate and reliable CFD predictions are needed to help design future Mars entry, descent, and landing (EDL) vehicles due to the cost and limitations of wind tunnel tests. Typical Reynolds-averaged Navier-Stokes (RANS) approaches struggle at points along the Mars EDL trajectory with high enough altitude (low enough ambient pressure) that the SRP motor plumes are over-expanded. This work demonstrates how high-order scale-resolving simulations on Cartesian adaptive mesh refinement (AMR) grids can provide accurate and reliable time-averaged aerodynamic loads on the vehicle for this challenging flow regime. Greater than second order convergence in the time-averaged integrated axial force (𝐶𝐴) is obtained across the three finest mesh resolutions simulated, and the estimated uncertainty is smaller than the unsteady standard deviation – demonstrating the accuracy and reliability of the method. This approach can yield higher confidence in 𝐶𝐴 than previously obtained in a reasonable turnaround time and is within reach for a few points in the trajectory (i.e. Mach 2.4, 2.52, and 2.78). Further computational performance and numerical methods improvements are needed to reduce the cost enough to bring this method into the EDL engineering design cycle.

Biography

François Cadieux is a research aerospace engineer in fluid mechanics working in the Computational Aerosciences Branch of the NASA Advanced Supercomputing Division at NASA's Ames Research Center. He received the NASA Early Career Public Achievement Medal in 2018 for enhancing the safety and success of the Orion Launch Abort System through high-fidelity computational aero-acoustic predictions of the QM-1 test and launch abort scenarios. Cadieux joined the Launch, Ascent, and Vehicle Aerodynamics (LAVA) team in September 2016. He completed a postdoctoral fellowship at the Flow Physics and Computation Lab under the supervision of Prof. Rajat Mittal at Johns Hopkins University from 2015 to 2016. His research focused on developing and validating wall-modeled large-eddy simulation (LES) for separated flows. Cadieux also investigated the dynamics of active flow control to mitigate flow separation and delay stall. During his graduate work with Prof. Julian A. Domaradzki, Cadieux probed the limits of under-resolved LES for separated flows applicable to small unmanned aerial vehicles and low-pressure turbines and quantified the importance of numerical dissipation effects when performing LES on coarse grids. He obtained his Ph.D. in aerospace engineering from the University of Southern California in 2015.