Effects of Spline Mid-Passage Gap on Turbine Endwall Film Cooling Characteristics

Abstract

The mid-passage gap exists on the turbine blade platform. The coolant stored in the disk cavity will penetrate through the gap to the endwall, which will form a coolant film to protect the endwall. To investigate the cooling performance of spline mid-passage gap leakage on the endwall, numerical research was performed in a linear cascade and was verified by experiment. The film cooling effectiveness was measured with a pressure sensitive paint method. Then the aerodynamic performance was discussed. The experiment and numerical calculations were carried out at a mainstream inlet Mach number of values 0.12, and the leakage mass flow ratio values 0.5%. The effects of spline point locations and shapes on cooling performance were calculated. The aerodynamic loss of different point locations and shapes were discussed. The results proved that the center spline case will enhance the cooling and reduce the aerodynamic loss when the distance of the alternative and original position values is 0.1 and 0.2 times of pitch. As the midpoint gradually moves away from the original position, the pressure loss also gradually decreases. The case with distance of the alternative and original position values 0.2 times of pitch has the highest film cooling effectiveness among all cases while its pressure loss is lower than the baseline.