Numerical Investigation on Supersonic Film Cooling Performance with Discrete Film Holes

Abstract

The effect of the discrete film cooling hole type on flow characteristics and the cooling performance of supersonic film cooling are numerically studied on a flat plate. Three film hole types (cylindrical hole, merged hole, and sister hole) are evaluated. Numerical simulation is conducted under a constant mainstream Mach number and six coolant Mach numbers ranging from [Formula: see text]. The three-dimensional effects of shock impingement on the flow characteristics and cooling performance are analyzed. The flow features (especially the interaction between the jet flow and the mainstream) are illustrated. The results show that the supersonic film cooling performance is heavily affected by many factors: the shear layer developed from the detached boundary layer, the boundary-layer separation downstream of the film hole, the jet liftoff phenomenon, the kidney vortex, and the oblique shock wave impingement. Those factors, except for the shock wave impingement, are heavily affected by the discrete film hole types and coolant Mach numbers. The shock impingement is not conducive to the lateral expansion of the cooling film. There is an optimal coolant Mach number for the best film cooling effectiveness under three film hole types, and the sister hole yields the best cooling performance.