Abstract: Hypersonic flows around a blunt body are studied with numerical simulation and theoretical analysis.Correlations between plasma prediction and gas components are obtained.It shows that it is Mach number which affects the peak number density of electrons.Numerical simulation agrees with theoretical analysis well.Differences between two gas models get greater as Mach number increases.The differences follow same trend at back taper with stagnation region.A 11-species chemical model should be applied to increase accuracy when reentry capsule flight at height of 60 km and Mach number is over 23.

Key words: reentry vehicle, plasma, gas components, chemical reaction model, numerical simulation