A Study of the Numerical Simulation of Secondary Flows in Turbine Stator Cascades

By adopting CFD(computational fluid dynamics)Software Fluent a numerical solution for the three-dimensional flows in turbine stator cascades featuring a big turning angle has been achieved.The secondary flows along the flow direction on various sections of the cascade and its aerodynamic characteristics were analyzed along with an investigation of the influence of any change in blade height and inlet incidence on cascade secondary flows.It has been found from the calculation results that the intensity of the secondary flows,which move from the cascade pressure surface to the suction one,increases gradually along the flow direction,giving rise to the continuous consolidation of the boundary layer on endwall near the suction surface and also a curling-up at the rear portion.Moreover,the foregoing also has led to a drastic change of the total pressure loss coefficient and the outlet flow angle along the blade height.A comparison of the various cascade operating conditions shows that a decrease of blade height and an increase of incidence will drastically increase the cascade secondary-flow losses,the intrinsic cause of which invariably lies in the expansion of the area occupied by the secondary flows in the cascade passage.