In order to design a thermal protection system for hypersonic vehicles, it is important to predict the heat transfer rate precisely. For this purpose, an effective method for calculating the heat flux at the stagnation point for hypersonic vehicles is developed. The variable specific heat of air is considered in the calculation of changes of temperature behind the shock wave, while the effect of real gas is considered in the calculation of the heat flux at the stagnation point. The air's heat capacity and the ratio of the specific heat are calculated based on the Peng-Robinson equation of state, and their fitting formula can be obtained against temperature. The typical stagnation point heat flux for a blunt body is calculated. The results are compared with the experimental data and data from the fitting formula in literature. The results show that the method is convenient and accurate. Reliable data can be provided for the aero-thermal calculation in the initial design and for the reasonable choice of the thermal protection system for hypersonic vehicles.

variable specific heat  /  hypersonic  /  P-R equation of state