HYPERSONIC RAREFIED FLOWS DSMC ANALYSIS BY A SIMPLIFIED CHEMICAL-MODEL

A simplified model for the analysis of molecular and reaction dynamics in hypersonic flows of rarefied gases is used to investigate the infl uence of oxygen dissociation in the prediction of aerothermal coeffici ents. The model is a direct simulation Monte Carlo method derived from the Larsen-Borgnakke method for the analysis of inelastic collisions. Tests performed in conditions near to re-entry conditions at an altit ude of 115 km show significant effects of chemical reactions on the ev aluation of the heat-transfer coefficient, while no real influence is found on lift and drag coefficients. Good agreement is found with resu lts achieved using more sophisticated chemical models, as a 4 % maximu m difference arises in the determination of surface quantities in re-e ntry conditions at 160 km.