Numerical Prediction of the Shock-Wave Structure Over a Reentry Brazilian Capsule

Abstract

This work presents computational results of the shock-wave structure for typical hypersonic flow conditions encountered by the small ballistic reentry Brazilian vehicle SARA (acronyms for SAt lite de Reentrada Atmosf rica). Most of the transition flow regime is covered by the altitude range of 120 to 80 km. Calculations were made with the Direct Simulation Monte Carlo (DSMC) method that accounts for translational, rotational, and vibrational non-equilibrium effects. The primary aim of this paper is to
examine the behavior of the shock-wave structure during the high altitude portion of SARA reentry. In
this fashion, the influence of rarefaction on the shock-wave standoff distance, shock-wave thickness, and
shock-wave shape will be investigated for altitudes of 100, 95, 90, 85 and 80 km, and by a model that identi®es the molecules in three distinct classes: (1) undisturbed freestream, (2) re¯ected from the body surface, and (3) scattered, i.e., molecules that were indirectly affected by the presence of the capsule.
Interesting aerodynamic features on blunt nose were observed from the results. It was found that the
shock-wave standoff distance decreased with decreasing the altitude.