Numerical Computation and Optimization of Turbine Blade Film Cooling

Abstract

The effect of film cooling parameters on the cooling effectiveness of an actual turbine blade is studied numerically. Film cooling parameters such as the hole shape, holes distribution, blowing ratio, streamwise angle, and spanwise angle are investigated to select the appropriate cooling parameters. Unstructured finite volume technique is used to solve the steady, three-dimensional, and compressible Navier-Stokes equations. Using one cooling holes array indicates that the average overall film cooling effectiveness is enhanced by decreasing the streamwise angle for high blowing ratio on the suction side of the turbine blade. The film cooling effectiveness is enhanced on the pressure side for a blowing ratio of unity. In addition, the cooling effectiveness increases by increasing the lateral and forward diffusion angles.The computations reveal that the efficiency of cooling is decreased at the leading edge due to the large surface curvature of the blade. The presence of compound shape (spanwise angle) enhanced the film cooling effectiveness on the two sides. Multistagger cooling hole arrays are investigated and the results indicate that five-stagger cooling arrays on the pressure side and three-stagger cooling arrays on the suction side with LFDCA-9.3-14.6 hole shape are enough to have good cooling of the two sides using 2.17% bleed air of the engine.