Numerical investigation on the characteristics of cavity-transpiration combined cooling for hypersonic vehicle leading edge

Abstract

During the flight of hypersonic vehicles, the wedge-shaped leading edge is exposed to severe thermal loads, so a reliable cooling system is required to provide protection. Transpiration cooling has been shown to be an efficient thermal protection technique for hypersonic vehicles. In this paper, the cavity-transpiration combined cooling is applied to the wedge-shaped leading edge of vehicles and an optimization scheme of lip blunting for the combined cooling is proposed. The effects of flight angle of attack, aspect ratio of the cavity and coolant injection mode are studied using the full field coupled numerical method. And the cooling characteristics of cavity-transpiration combined cooling with lip blunting are analyzed. The results reveal the following novel and valuable phenomena: (1) The existence of the cavity reduces the lift-drag ratio of the leading edge, and the lift drag ratio increases with the increase of the angle of attack. (2) When no coolant is injected, the temperature and pressure of the stagnation point decrease with the increase of the length and diameter of the cavity. When the coolant is injected at a constant mass flow rate, the cooling efficiency at stagnation point decreases with the increase of cavity length and diameter, but the driving force decreases. When the coolant is injected at a constant pressure, the mass flow of the coolant increase, the cooling efficiency at the stagnation point is increased by 9%. (3) The temperature at the stagnation point of lip blunting structure is decreased by 94.78 K compared with no blunting, and the cooling efficiency is increased by 9.8%.