The Effect of Rotor Casing on Low-Pressure Steam Turbine and Diffuser Interactions

Abstract

The present study aims to investigate the interaction between a last-stage steam turbine blade row and diffuser. This work is carried out using computational fluid dynamics (CFD) simulations of a generic last-stage low-pressure (LP) turbine and axial–radial exhaust diffuser attached to it. In order to determine the validity of the computational method, the CFD predictions are first compared with data obtained from an experimental test facility. A computational study is then performed for different design configurations of the diffuser and rotor casing shapes. The study focuses on typical flow features such as effects of rotor tip leakage flows and subsequent changes in the rotor–diffuser interactions. The results suggest that the rotor casing shape influences the rotor work extraction capability and yields significant improvements in the diffuser static pressure recovery.

Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

“…Based on the understanding of the flow interaction between the axial turbine and the exhaust volute, Singh et al 26 performed the computational study of the flow fields for different design configurations of diffusers with different turbine rotor casing contours, and the study mainly focused on the typical flow features such as effects of rotor tip leakage flows and subsequent changes in the rotor-diffuser flow interactions. The computational results further suggested that the rotor casing shape influences the turbine rotor work extraction capability and yields significant improvement in the static pressure recovery.…”