Effect of upstream slot leakage on turbine endwall film cooling characteristics

Abstract

To investigate the effect of the upstream slot leakage on the endwall film cooling characteristics, the PSP (Pressure Sensitive Paint) technology was applied to measure the turbine blade endwall film cooling characteristics of upstream leakage flow on a linear cascade, and the aerodynamic performance of the passage was numerically analyzed. The effect of the upstream slot leakage mass flow ratio (0.4%∼1.5%) and its position (0.2Cax∼0.5Cax) on the film cooling and the aerodynamic performance were analyzed. The results showed that a rising mass flow ratio of the upstream slot could enhance the film cooling effect at the turbine endwall, increase the coverage area of coolant on the endwall surface, weaken the passage vortex strength, and reduce the aerodynamic losses. While under the same mass flow ratio, reducing the distance between the slot and the blade leading edge would increase the film cooling effect, and inhibit the entrainment effect of the passage vortex on the coolant, but will not influence the leakage coverage area. The distribution of leakage flow is dominated by the secondary flow. When the slot is located on 0.3Cax in front of the passage inlet, the aerodynamic loss of the linear cascade is the minimum in all cases.