Chemically reacting hypersonic flows over 3D cavities: Flowfield structure characterisation

Abstract

In this paper, a computational investigation of hypersonic rarefied gas flows in the transitional flow regime over 3D cavities is carried out by using the direct simulation Monte Carlo method. Such cavities give rise to geometric discontinuities that are often present at the surface of reentry vehicles. This work is focused on the flowfield structure characterisation under a rarefied environment and in the presence of chemical reactions. The cavities are investigated with different length-to-depth ratios, and the different flow structures are studied. In particular, for length-to-depth ratios of 1 and 2, a single recirculation is observed inside the cavities and the main flow is not able to enter the cavity due to the recirculation structure and high particle density. In the case of length-to-depth ratio 3, the flow is able to partially enter the cavity resulting in a elongated recirculation and the beginning of a secondary recirculation core is noticed. For the case of values 4 and 5, the main flow is able to penetrate deeper into the cavities and two recirculation zones are observed; however, for the length-to-depth

DSMC simulation of rarefied gas flow over a 2D backward-facing step in the transitional flow regime: Effect of Mach number and wall temperature

“…The present study does not include vibrational temperature, which is expected to be much smaller. 73,76,92 In the plots, each of the temperatures is normalized by the free stream temperature Tnormal∞. For a polyatomic gas, when the temperatures corresponding to the rotational, overall, and translational modes are dissimilar, it indicates thermal non-equilibrium, as observed in the present study.…”