ON THE PREDICTION OF FLOW PATTERNS AND LOSSES IN HP AXIAL TURBINE STAGES USING 3D RANS SOLVER WITH TWO TURBULENCE MODELS

An experimentally tested air turbine stage and a real high-pressure (HP) steam turbine stage are calculated using the 3D RANS solver FlowER supplemented with the Baldwin-Lomax and Menter shear stress transport (SST) models. The computations of the model air turbine stage show that the Menter SST model gives better agreement with the experimental data as far as the span-wise distribution of exit velocities and swirl angle. The comparison of performance of the two turbulence models exhibits differences in predicting flow patterns and losses in the considered HP turbine stage. The main differences concern the development of secondary flows and separations. There is a significant span-wise redistribution of losses between these two models. The tendency is that for the same relatively refined grid resolutions, the level of pitch/span averaged losses for the Menter SST turbulence model is slightly above that of Baldwin-Lomax.