Effect of ionization reaction on aerodynamic heat characteristics for vehicle in hypersonic rarefied flow was studied by using direct simulation Monte Carlo (DSMC) method in which ionization reaction model was added. For the actual difficulties added by electron in rarefied flow

a bundling method was used to deal with electron motion. The ionization reaction model and the processing method of ionization reaction were presented. Firstly

taking the example of shape of RAM-C Ⅱ vehicle

DSMC code with addition of ionization reaction was validated. Then

a numerical experiment was made to investigate the effects of ionization reaction on aerodynamic heat characteristics of the Stardust blunt body at different altitudes by use of 5 species gas model(without ionization) and 11 species gas model(with ionization) in chemical non-equilibrium flow. The results show that the treatment scheme proposed can simulate ionization reaction for hypersonic rarefied flow. At 60km altitude

ionization reaction effect on the aerodynamic heat characteristics becomes the strongest

reducing heat flux at stagnation point by 5.12%

and the effect decreases with the increase of the rarefied content of gas.