Analysis on improvement of film cooling effectiveness with small coolant jets

The primary focus of this paper is to further understand the flow and heat transfer characteristics of a special film cooling configuration where in the main film cooling hole is accompanied by two smaller jet holes.The adiabatic effectiveness and the interaction between the main hot stream and the coolant jets were simulated and analyzed by comparing with the standard single hole structure at different blowing ratios.It is found that the presence of smaller jets decreases the size and strength of the counter-rotating vortex pair of the main coolant jet and so does its mixing with the main hot stream.The coolant jets remain much closer to the surface.This avoids jets lift-off for the stand single hole structure at high blowing ratio.The surface adiabatic effectiveness value is enhanced as expected.A higher blowing ratio means more obvious improvement of film cooling effectiveness.