Aerothermal investigation of an atmospheric reentry capsule using direct simulation Monte Carlo with ab initio rates for internal energy relaxation and chemical kinetics

The direct simulation Monte Carlo (DSMC) method is used to simulate the aerothermochemical environment surrounding an axisymmetric model of the Varda Space Industries W-2 reentry capsule. In situ optical emission spectroscopy flight data are used as benchmark data for assessing the performance of recent first-principles results for neutral air transport properties, internal energy relaxation rates, and chemical kinetics. This extensive set of quantum chemistry data is used for the first time in large-scale DSMC simulations of a reentry vehicle. The DSMC flow field results are used to simulate line of sight radiative emission spectra using NASA’s High-temperature Aerothermodynamic Radiation Algorithm (HARA). A comparison between simulated and flight spectra at 78 km demonstrate improved fidelity of the first-principles-informed DSMC method compared to computational fluid dynamics (CFD) based on legacy two-temperature thermochemical nonequilibrium models. A roughly 30 % improvement on the total radiance prediction is obtained from DSMC compared to CFD.