A NOVEL PREDICTION MODEL FOR THE AERODYNAMIC LOSSES INCREASE DUE TO FILM COOLING INJECTIONS FROM GAS TURBINE VANE SURFACE

In this paper, experimental and numerical investigations were conducted on the aerodynamic performance of a turbine vane cascade with film cooling injections. The impact of coolant injection on aerodynamic losses was investigated, and thus a novel prediction model was proposed to estimate the aerodynamic penalty associated with film cooling injections. Three-dimensional numerical simulations performed in this paper were based on the commercial CFD solver ANSYS CFX. To analyze the effects of hole position on the aerodynamic performance, a validated computational model was proposed for the turbine vane cascade with single row film holes either on the suction surface, the leading edge, or the pressure surface. Total pressure loss coefficients were further evaluated and analyzed for typical ranges of blowing ratio (0.5 to 1.5) and coolant injection angle. It is found that, total pressure loss coefficients increase with increasing blowing ratio to different extent depending on the hole position, and the loss associated with coolant injection from the suction surface are highest. Using co-relation mathematical models to predict the penalty is challenging due to the complicated three-dimensional flow structure. The applicability and accuracy of a published loss model, Hartsel model, were evaluated in this study. The prediction of Hartsel model showed largely dependent on the local Mach number of mainstream and the velocity of coolant injection. This suggests that the Hartsel model can't predict total pressure losses for various locations of turbine airfoil cascade well. For these reason, this present work further develop the applicability and accuracy of the Hartsel model to a satisfactory level. Results indicate that the present model can accurately predict total pressure loss coefficients of film holes at different positions when the blowing ratio is in the range of 0.5 to 1.5 and the incidence angle of cooling air varies in a specified extend.