Experimental and numerical investigations of discrete film holes cooling performance on a blade endwall with mid-passage gap leakage

Abstract

The blade endwall of gas turbine endures high thermal load which is urgently needed to be cooled using film cooling technique. To investigate the cooling characteristics with discrete holes and mid-passage gap, experimental research was performed in a linear cascade equipped with six blades, the cooling effectiveness was measured with PSP technology. And a verified turbulence model was selected to clarify the flow field and aerodynamic losses of blade passage. The experiment and numerical calculations were carried out at a mainstream flow inlet Mach number (Ma) values 0.12 and at a discrete hole blowing ratio from 0.5 to 3.0. At first, the effect of different cooling unit arrangements and hole shapes on the cooling effects were investigated. Then, the aerodynamic loss of different hole arrangements and shapes on the passage were discussed. The results show that the cooling performance of the mid-passage gap has little influence on the coverage of coolant from the upstream discrete film holes. The arrangement-1 of the discrete fan-shaped holes present the best cooling performance compared with the other arrangements cases and cylindrical hole case.