Effect of continuous or discrete shock wave generators on supersonic film cooling

The present study investigates the flow fields for supersonic film cooling with various three-dimensional shock wave generators. This study investigates the effect of the shock wave intensity, shock wave generator width and coolant inlet Mach number on the supersonic film cooling. The results indicate that the impinging shock wave increases the wall pressure and the turbulent kinetic energy in the boundary layer, with the lower Mach numbers in the boundary layer reducing the film cooling effectiveness for the cases with the shock wave generator as wide as the flow channel. For a shock wave generator that is not as wide as the flow channel, the pressure and film cooling effectiveness are not evenly distributed. A wider shock wave generator reduces the film cooling effectiveness upstream of the protected wall. The 30 mm shock wave generator had the lowest film cooling effectiveness in the middle part and downstream of the protected wall mainly because the uneven pressure distribution causes a z-direction secondary flow in the boundary layer which reduces the cooling film layer thickness in the middle part of the protected region and increases the interaction between the cooling stream and the main stream which reduces the film cooling effectiveness.