Computational Analysis and Optimization of Blowing Ratio for Effective Film Cooling of a Gas Turbine Blade

Film cooling is vital to gas Turbine blades so as to protect them from the high temperatures and thermal stresses caused due to the flow of hot combustion gases on the surface of the blade. This study focuses on the efficient computation of film-cooling flows. Initially Computational analysis was done on a flat Plate with holes inclined at 35° to the surface plate. The results obtained were verified and compared to previous experimental measurements. Further, Film cooling effectiveness of a gas turbine blade was studied by using a row of inclined holes at 30° to the surface of the blade. The density ratio of the Coolant (i.e. air) to mainstream was varied from 1.2 to 2.0 while the velocity ratio was varied from 0.208 to 0.83. The surface temperature of the blade was measured with the help of Ansys CFX 14.5 where temperatures were obtained along the jet centreline and across other locations of the blade. A point along the centreline has been taken where the jet remains attached to the surface of the blade and temperatures were recorded while varying the density&velocity ratios. The results obtained were modelled and Regression Analysis was performed to find the contribution of the above parameters on the effectiveness of film cooling. An equation has been derived and decoded to find the optimum value of blowing Ratio for maximum effectiveness at the selected point on the surface of the blade.