Simulation of Unsteady Flows in Intermediate Pressure Steam Turbine with Cutback Stator Blade Row

Abstract

This paper presents numerical simulation of unsteady flows through three-stage stator and rotor blade rows in an actual middle pressure steam turbine while setting cutback first-stage stator blades and original stator blades. The shapes of original blades were measured from actual blades using 3D scanner during overhaul. Three different cutback length are considered to find out the influence on unsteady flows through the turbine blade rows and the performance of intermediate pressure steam turbines. The simulation employed numerical method developed by Tohoku University. The obtained numerical results indicate that the cutback stator blades certainly affected the steam flow velocity and outlet flow angle after the stator blade rows, resulting in a negative influence on the adjacent rotor blades, which depends on the cutback length.