Prediction of losses in flow through the last stage of LP steam turbine

The aim of presented work was the prediction of the losses in the wet steam flow through the last stage of 200MW steam turbine LP part. To this end, three numerical tools were used. The first method was the streamline curvature method (SCM) used on the meridional plane with losses correlations. The next two methods, TASCflow commercial CFD code and an in-house CFD code, based on the solution of the Reynolds-averaged Navier-Stokes equations (RANS). Application of three independent numerical tools allowed to make the more reliable losses analysis and made possible to compare applied numerical methods with each other. For the flow modeling in the last stage of LP steam turbine the various two-phase flow models were used and compared. The equilibrium model and non-equilibrium models with homogeneous and/or heterogeneous condensation were considered. The boundary conditions at the inlet and outlet from the stage were selected in such way to get the beginning of the homogeneous condensation process in the stator. It corresponded to the part load of the turbine, i.e. 140MW power and pressure in condenser 2.7kPa.