Numerical simulation on film cooling with compound angle of blade leading edge model for gas turbine

Abstract

Film cooling performances of the cylindrical film cooling holes with different compound angles on the turbine blade leading edge model are investigated in this paper. Several numerical simulation results are compared with available experimental data, under different blowing ratios. Three rows of holes are arranged in a semi-cylinder model which is used to model the blade leading edge. These three rows of holes have a compound angle of 90° in the flow direction, 30° along the spanwise direction. Besides, the two rows on either side of the stagnation row have an additional angle in the transverse direction. Five different film cooling hole compound angles in the transverse direction and four different blowing ratios are studied in detail. The results show that as the blowing ratio increases, the trajectory of the film jets in the leading edge region deviates gradually from the mainstream direction to the spanwise direction, for all cases studied. And film cooling effectiveness increases with the increasing blowing ratio while a slight decrease appears as the blowing ratio approaches 2.0. In this study, the optimal value of M is around 1.4. For the Baseline Case, the overall averaged cooling effectiveness increases by more than 0.1, compared with M=0.7. The holes with negative additional compound angle have better performance of cooling. On the one hand, the improvement of film cooling effectiveness increases with the increasing negative compound angle, before it reaches -30°. On the other hand, with the increasing blowing ratio, the improvement of the cooling performance due to negative additional compound angle is more significant. For γ=−30°, the increase of overall averaged cooling effectiveness varies from 1.75% to almost 20%, with the increase of M.