Experimental Cascade Simulation of First Stage High Pressure Gas Turbine with Effects of Leakage Flow and Contouring on Endwall Film Cooling

Abstract

Flow in a high pressure gas turbine passage is complex involving systems of secondary vortex flows. This complexity causes difficulty in providing film cooling coverage to the thermally loaded hub endwall region. An improved understanding of the effect of these flow features on endwall heat transfer is needed to assist designers in developing efficient cooling schemes. The present experimental study is performed in a linear, stationary cascade with a contoured endwall, representing first stage stator of a high pressure gas turbine. Passage thermal fields and endwall adiabatic effectiveness values are measured. Engine representative conditions such as high free stream turbulence, large eddies, high Reynolds number, varying coolant mass flow ratios, and non-uniform approach flow temperature profiles are set up. Results show that the combined effect of slot geometry, endwall profile shape, and coolant mass and momentum flux ratio, is an important determinant in assessing film cooling effectiveness.