EFFECTS OF CHEMISTRY ON BLUNT-BODY WAKE STRUCTURE

Results of a numerical study are presented for hypersonic low-density flow about a 70-deg blunt cone using direct simulation Monte Carlo (DS MC) and Navier-Stokes calculations. Particular emphasis is given to th e effects of chemistry on the near-wake structure and on the surface q uantities and the comparison of the DSMC results with the Navier-Stoke s calculations. The flow conditions simulated are those experienced by a space vehicle at an altitude of 85 km and a velocity of 7 km/s duri ng Earth entry. A steady vortex forms in the near wake for these frees tream conditions for both chemically reactive and nonreactive air gas models, The size (axial length) of the vortex for the reactive air cal culations is 25% larger than that of the nonreactive air calculations. The forebody surface quantities are less sensitive to the chemistry t han the base surface quantities. The presence of the afterbody has no effect on the forebody flow structure or the surface quantities. The c omparisons of DSMC and Navier-Stokes calculations show good agreement for the wake structure and the forebody surface quantities.