Lessons Learned from Supersonic Retropropulsion Wind Tunnel Testing and Computational Analysis

Testing was completed in the NASA Langley Unitary Plan Wind Tunnel to investigate aerodynamic interference on sub-scale Mars powered descent vehicle concepts at Mach numbers of 2.4 to 4.6: a model of a blunt hypersonic inflatable aerodynamic decelerator (HIAD) and the other representing a slender vehicle with body flaps (CobraMRV). Measurements included high-speed video, discrete pressures, and pressure sensitive paint. High-speed imagery revealed an unsteady plume/shock interaction for certain thrust levels and model attitudes, resulting in unsteady pressures on the model heatshields. Computational flowfield predictions of varying fidelity were completed using three solvers, and were compared to the test data. Qualitatively, the predicted gross flowfield features compare well to the high-video imagery. Overall, the computed heatshield pressure coefficients are consistent between solvers and follow the trends revealed in the time-averaged data. More advanced turbulence modeling methods are able to capture highly-unsteady pressures measured on certain models at some conditions. The test data will continue to be used to guide future testing investments and best practices for computational methods.