Effect of leakage flow on the endwall cooling performance in high subsonic turbine cascade

Abstract

Gas Turbine is widely used in many fields, for the purpose of achieving higher efficiency, the main flow temperature needs to be improved. In the combustion chamber, the flame profile is designed to be a flat pattern distribution to reduce NOx, as well as to decrease thermal load. Thermal protection for the hot-end components has become an important issue.Within the present study, experimental and numerical methods are used to investigate the effects of leakage flow on cascade endwall cooling performance for high subsonic flow condition. Test variable including blowing ratio and upstream slot inclination angle. Blowing ratio(M) ranged from 0.3 to 2, upstream slot inclination angles are 0°, 45°,60°.The results stated that when the blowing ratio increases, the magnitudes of adiabatic cooling effectiveness increases, but the growing slope decreases. It is showed that the optimal performance is observed at a test condition of blowing ratio around 1.7. Under low blowing ratio (0.3–0.6) condition, the adiabatic cooling effectiveness of suction side is significantly better than the pressure side. As the blowing ratio increases, the coverage of coolant on endwall becomes more uniform, and the endawall thermal loads decreases.When compared at a particular value of blowing ratio, a higher adiabatic cooling effectiveness zone approaches to the suction side with a 45° slot inclination angle compared to 30 and 60° inclination angle. Changing the upper stream slot inclination angle, the local distribution of adiabatic cooling effectiveness is varied, but the spanwise averaged values of η do not show discernible variation.