Numerical Study On Compound Angle Film Cooling On Endwall Of A Turbine Stator Blades

There is a wide range of secondary flows on the endwall surfaces of a turbinepassage, which is responsible for heat transfer enhancement, high temperature andpoor film cooling effect of part region of the endwall. Compared with blade surfacefilm cooling, the flow patterns and cooling effect of endwall film cooling is extremelycomplex. It is very important for engineering designing to predict the endwall filmcooling effect exactly.Four rows of cylinder film cooling holes are allocated at21，51，81percent ofaxial blade chord and9percent upstream of leading edge respectively on the turbinecascade endwall. Endwall film cooling effect and flow patterns of both single andcompound angle are analyzed using CFD method on the effect of the jet injectionangle and blowing ratio. The endwall film cooling effectiveness is analyzed underdifferent conditions of blowing ratio, axial angle and radial angle, based on whichoptimal arrangement of above cooling holes is obtained via orthogonal algorithm.Adjust the configuration of cooling holes of the best scheme and do further researchabout better configuration to analyze endwall film cooling effectiveness and theinfluence of film cooling holes on the surface temperature field of stator blade.Results show that the advantage of compound angle jet could be welldemonstrated when α=30°. The averaged effectiveness of compound angle could beincreased by16.4%than single angle; the compound angle jet can cause the decreaseof axial momentum and the increase of horizontal momentum, which weakens therole of secondary flow in main jet and strengthen the endwall of the film; hignestcooling effectiveness may be reached when blowing ratio is2.0, axial angle is30°and the radial is45°, which is seemed as optimum scheme under combined action ofabove three factors; the blowing ratio has greatest influence on the coolingeffectiveness, followed by radial angle and axial angle; the local cooling effect improve when extra film holes are allocated along the blade suction side corner. Eachblowing ration increased by0.5, average endwall film cooling efficiency will increaseabout0.05of the improved hole row.