Experimental study on cooling performance of a steam-cooled turbine blade with five internal cooling smooth channels

Advanced cooling technology is a key measure of thermal protection for turbine blades, and raising inlet gas temperature of gas turbines. Using steam as a coolant in the internal cooling channels of turbine blade can significantly reduce the consumption of air drawn from the compressors and the closed circuits convective steam cooling can help to avoid the mixing loss between the mainstream and the cooling air so as to raise the overall efficiency of gas turbine. In this study, cooling performance comparison between the steam and air is conducted on a test blade with five smooth radial convective cooling channels. The temperature and static pressure on the surface of the mid-span of the test blade are measured and the cooling performance of the blade under different cooling conditions is evaluated. Results show that the middle region of the test blade has the highest cooling effectiveness, and then the leading edge follows. The cooling effectiveness at the trailing edge is the lowest. At the same mass flow rate, the averaged cooling effectiveness of steam cooling is higher than air by about 0.12. To obtain a similar cooling performance, the consumption of cooling steam is only 40.82% of the cooling air. In conclusion, steam cooling can achieve a better cooling performance than air, and improvements of cooling structure for the trailing edge is required for steam-cooling application in the given configuration.