Effects of feeding pressures on the flowfield structures of three-dimensional film cooling

A Mach 2.6 annular supersonic nozzle was designed to protect a hypersonic cone. The annular nozzle is able produce tangential cooling film around the cone. Experiments were carried out in a hypersonic wind tunnel under different cooling film feeding pressures and different attack angles. Temperature-sensitive paint (TSP) was used to measure surface temperature of the cone body; schlieren method was applied to visualize the flow structures. TSP results showed that cooling film can obviously decrease surface heating load, but its efficiency was influenced by the angle of attack. Schlieren results showed that the shape of upper-lip shock wave is similar to an arc, and the reflected shock wave is more closer to a straight line; both the tilt rate of upper-lip shock wave and the reflected shock wave were increased exponentially with the rise of feeding pressure; a higher feeding pressure resulted in a larger curvature of upper-lip shock wave; compared with reflected shock wave, upper-lip shock wave and shearing layer were more easily affected by the feeding pressure. With higher feeding pressure, incidence point was moved to the further downstream location, and a fitting formula is given to express the relationship between the position of the shock wave incidence point and the feeding pressure.