Thermal protection of a hypersonic vehicle by modulating stagnation-point heat flux

The heat flux at the stagnation-point is usually used to evaluate the heat transfer efficiency between high-temperature gas and a hypersonic flying vehicle. Controlling the stagnation-point heat flux is of critical important for the design of a thermal protection system for a hypersonic flying vehicle. In this work, we demonstrate that the nonequilibrium molecular dynamic (NEMD) method can well describe the shock wave and the stagnation-point heat flux. In particular, our results show that the heat flux is more sensitive to the change of the peak amplitude of the hypersonic flow in the bimodal velocity probability density function (PDF) at the stagnation point. Decreasing the peak amplitude of the hypersonic flow in the PDF can effectively reduce the stagnation-point heat flux. Three types of the outer shapes for the flying objects are employed to compare the heat flux at the stagnation-point. The NEMD simulation results confirmed that the heat flux can be decreased 16.8% for the spherical cavity outer shape compared with the flat shape in the leading edge.