Numerical study on film cooling characteristics of BESA hole with water mist/air two-phase flow

In view of a new type of film cooling hole, the backward-expanding shoulder arm(BESA) hole proposed by the author, a numerical model of two-phase flow film cooling with water mist is established. The numerical simulation of water mist / air two-phase flow film cooling characteristics shows that the comprehensive performance of water mist / air two-phase flow film cooling is significantly improved compared with pure air film cooling. For the round hole plate model, when the blowing ratio is 0.5, the film cooling efficiency of two-phase flow film cooling with 2% water spray is 37.5% higher than that of pure air film cooling (20D from the film hole outlet), When the blowing ratio is 1.0, the film cooling efficiency of the flat two-phase flow with 2% water spray is 49.0% higher than that of the pure air film cooling (20D away from the film hole outlet). When the spray amount of water is the same, the film cooling efficiency of the BESA hole is higher than that of the round hole, the expanding hole and the shoulder arm hole. For the flat film cooling model of the BESA hole, When other factors remain unchanged, the cooling efficiency of the two-phase flow film increases monotonously from 2% to 5%. The cooling characteristics of the two-phase flow film on the pressure surface of the turbine blade of the BESA hole are similar to those of the flat model, and the film coverage effect is better than that of the round hole, the expanding hole and the shoulder arm hole.