Film Cooling Performance on a Turbine Blade with Subregional Compound Angle

Under the function of passage secondary flow, film cooling deviates from the streamwise on turbine blade which directly, not what we want, results in uneven film coverage. On pressure side, film appears divergent while it is bunched on suction side. To solve this problem, Subregional compound angle is proposed. Based on the experimental result, the design scheme of multiple working cases and compound angles is implemented. Results show that five regions along the spanwise could be divided on pressure side. Under the effect of horseshoe vortex, the film deviation in the root region is the most serious. When the compound angle increases to -30°, this phenomenon can be effectively weakened, and the deviation angle decreases along the streamwise as the horseshoe vortex gradually moves away from the blade surface. Different from pressure side, two subdivisions are added along the streamwise on suction side because, besides the horseshoe vortex, the effects of passage vortex grow up. In addition, the film deviation of the root region is more obvious than that of pressure side. The entrainment of stronger passage vortex makes the film improvement from increasing compound angle more difficult downstream of the suction side. Overall, compound angle can weaken the Counter Rotating Vortex Pair and improve the averaged film cooling effectiveness.