A Detailed View on the Mixing and Loss Generation Process During Steam Admission Concerning Geometry, Temperature and Pressure

Authors

D. Engelmann - Ruhr-Universität Bochum, Chair of Thermal Turbomachinery, Germany
R. Mailach - Ruhr-Universität Bochum, Chair of Thermal Turbomachinery, Germany

Abstract

Steam turbines used in industrial applications often contain several branches for the admission of steam. Those branches are placed at the axial connections of two stage groups or within a single module. Among geometrical parameters, different temperature and pressure levels have a great impact on the mixing process of main and branch mass flows and on the flow distribution in subsequent turbine stages. Therefore, it is essential to understand the loss mechanisms appearing at junctions of different mass flow partitions to guarantee a stable operation and a high efficiency in a wide range of steam load. A comprehensive parameterized numerical study of a generic steam admission junction is described in this paper which focusses on geometry dependencies as well as on temperature and pressure differences. The study is performed with a 3D RANS solver to determine several loss partitions, such as total pressure loss, wall friction and admission loss. The results of the flow simulations are compared to literature values and empirical loss assumptions with a detailed view on both main steam path and branch pipe.