Enhanced loss prediction for admission through circumferential slots in axial steam turbines

Authors

D. Engelmann, A. Schramm, R. Mailach - Ruhr-University of Bochum
T. Polklas, M.A. Schwarz - MAN Diesel & Turbo SE, Oberhausen, Germany

Abstract

Steam turbines used in industrial applications usually contain branches for the admission and/or extraction of process steam at specific pressure levels. In most cases such branches are placed at the axial connections of two stage groups. Losses appearing at these junctions are caused by wall friction, mixing of several flow partitions and interaction with adjacent stage rows. In the current work a three stage steam turbine configuration, which includes a circumferential slot for steam admission, is examined. In order to estimate the pressure loss depending on additional inflow, similarity to combining flow in a pipe junction is used. In a parameterised numerical study several fluids and turbulence models are compared and validated with measurements. After that, gathered insights of the parameter study are applied to the steam turbine configuration, where common features as well as differences to the pipe junction are illustrated.