Experimental Study of the Slot Film and Discrete Film Cooling Characteristics for the Endwall of Turbine Vane

The turbine endwall of a real engine is curved shape, and its cooling type is a superposition of the slot flow, leakage flow and discrete film cooling flow. Meanwhile the endwall cooling is influenced by the secondary flow of the gas flow. The reasons above make complex cooling characteristics on the endwall. In order to investigate the film cooling characteristics close to the configuration and working condition of the endwall of a real engine, the effects of the slot flow, leakage flow and discrete film cooling effectiveness on the curved endwall are studied using the high-speed wind tunnel(Reynolds number of the gas flow is 370000) and pressure-sensitive paint (PSP) technology. Meanwhile the influence of the cooling mass flow ratios on the endwall film cooling effectiveness is obtained. The results show that the slot film effectiveness on the endwall increases with the rise of slot cooling flow ratio. The slot cooling film covers the whole endwall by the flow ratio of 1.71%. The discrete film cooling has limited coverage on the endwall compared to the slot. The film coverage on the downstream area of the suction side is poor. The discrete film cooling effectiveness before throat becomes lower with the increase of the film cooling flow ratios. However after the throat, the discrete film cooling effectiveness becomes higher with the increase of the film cooling flow ratio from 1.3% to 1.9%. The total film cooling effectiveness involved in the slot flow, leakage flow and discrete cooling flow is 93.4% higher than the discrete cooling only owing to the superposition of the cooling film. The total film cooling has more uniform coverage on the endwall. © 2022, Science Press. All right reserved.