2014 , Volume 19, № 5, p.67-84

Direct Monte Carlo simulation of a high-enthalpy chemically reacting flow around a blunt body (flat-faced cylinder with rounded edges) was performed for conditions corresponding to entry to Martian atmosphere. At these conditions, surface chemical processes, such as surface molecular recombination, can significantly affect high-altitude aerothermodynamics. A molecular surface chemistry model was proposed to take into account the effects of heterogeneous chemical processes on high-altitude aerothermodynamics. The surface chemistry effects, as well as the rarefaction effects along with the domain for applicability of continuum approach, were investigated by comparing the results of Direct Simulation Monte Carlo and solutions of Navier - Stokes equations for rarefied and near-continuum flow regimes. We demonstrate that the effect of surface recombination to body aerothermodynamics is significant for the considered flow regimes. Surface reactions on a fully catalytic surface can increase the stagnation point heat flux up to 40%. The limitation for applicability of continuum approach due to rarefaction effects was demonstrated. For the case of the near-continuum conditions (Kn ≈ 0.002) the Navier - Stokes equations correctly predict the flow in the shock layer and the heat flux distribution. For the rarefied conditions (Kn ≈ 0.03), the continuum approach incorrectly describes the flow structure. It overestimates the dissociation rate, and predicts a lower heat flux to the surface.