Abstract: A CFD study on the reduction of aerodynamic heating on the nose of a reentry vehicle by an opposing jet thermal protection system is conducted, by means of which the flow field parameters, reattachment point position, surface pressure distribution and heat flux distribution are obtained. The physical mechanism of the reduction of heat flux is analyzed. The opposing jet interacts with the freestream to form a Mach disk which enables the freestream to flow to the edges rather than interact with the surface to produce aerodynamic heating. In addition, the jet flows back to form a cool recirculation region, which reduces the difference in temperature between the surface and the nearby gas, and thus reduces the heat flux. The larger the total pressure ratio, the lower is the aerodynamic heating. To study the effect of the intensity of the opposing jet more appropriately, a new parameter RPA is defined by combining the flux and the total pressure ratio. The study shows that the same shock wave position, reattachment point position, peak heat flux position and total heat load can be obtained with the same RPA with different fluxes and total pressure ratios, which means the new ratio parameter may account for the intensity of the opposing jet and be used to analyze its influence on the flow field and total heat load at the nose of a reentry vehicle.

Key words: opposing jet, aerodynamic heating, total pressure ratio, flux, thermal protection system