NUMERICAL ESTIMATION OF LOSSES IN STEAM FLOW THROUGH LP TURBINE BLADE ROWS

Abstract

The aim of this work is to estimate the losses in steam flow through an LP steam turbine rotor and the whole stage. Two types of losses occur in steam flow, aerodynamic (profile, secondary flow, leakage) and thermodynamic (due to addition of heat caused by condensation). The presented numerical results are split into two groups. First, a comparison of three different calculation methods of steam flow is carried out. To this end, the geometry of an LP steam turbine’s last rotor is chosen. The first examined method is the Streamline Curvature Method (SCM) used on the meridional plane with loss correlations, the other two being commercial and in-house CFD codes, solving the Reynolds-averaged Navier-Stokes equations for a 3D flow. The first two codes model equilibrium steam properties below the saturation line, while the latter models non-equilibrium steam properties. Finally, a comparison is made of the influence on loss prediction of various condensation models for the geometry of the penultimate stage, with the use of an in-house CFD code.