Turbine Blade Trailing Edge Slot Film Cooling Using PSP Technique
Zhihong Gao, Dong-Ho Rhee and Je-Chin Han
Film cooling effectiveness was measured for turbine blade trailing edge models with pressure side cutback. The trailing edge models were cooled by ejecting coolant from span-wise discrete slots located on the pressure side. Two mainstream flow conditions were considered: (1) the mainstream flow was not accelerated with a thicker boundary layer and (2) the mainstream flow was accelerated with a thinner boundary layer approached the upstream of slot exit. The effect of slot lip thickness and blowing ratios on film effectiveness under the two mainstream conditions were investigated. Based on heat and mass transfer analogy, the non-conductive pressure sensitive paint technique (PSP) was used to determine detailed film cooling effectiveness distributions. Results showed that the film cooling effectiveness increases with increasing of blowing ratios. Thinner lips offer better effectiveness. The film effectiveness decreases when the incoming mainstream boundary layer thickness decreases. The film cooling effectiveness was correlated and compared with the existing correlation. Results can be useful for turbine blade trailing edge region film cooling designs.
Keywords: Turbine blade, trailing edge, slot film cooling, pressure side cutback, blowing ratio, pressure sensitive paint technique.