Film-cooling characteristics of upstream ramp enhanced turbine blade surface cooling

Film cooling is widely used in high-performance gas turbines to reduce the surface heat fl ux. Placing a ramp upstream of a film-cooling hole improves the film-cooling effectiveness. In this work, the Reynolds-averaged Navier-Stokes equations with the k-ω SST model are solved to simulate heat transfer and fluid flow over an upstream ramp and two rows of injection holes. Three blowing ratios (M = 0.6, 1.0, and 1.6) and three upstream ramp angles (α = 0, 14° to 24°) are tested. It is found from the investigation that the film-cooling effectiveness increases with the upstream ramp angle and blowing ratio. Higher film-cooling effectiveness is noticed downstream of the second row holes than that of the upstream holes in the case without a ramp.