Numerical and experimental investigations of unsteay 3-D Wet-steam flows through two-stage stator-rotor cascade channels

Unsteady 3-D flows through two-stage stator-rotor cascade channels in a low-pressure steam turbine model developed by Mitsubishi Heavy Industry(MHI) are numerically and experimentally investigated assuming dry and wet-steam conditions. The fundamental equations for condensate flows derived by the authors are applied to the present flow computations. The high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD(Compact MUSCL) scheme and the Roe's approximate Riemann solver are used for the space discretization of convection terms. The pipelined LU-SGS scheme optimized for the parallel-implicit time-integration is also employed. MHI measured the total pressures, static pressures and yaw angles of flow velocity vectors at the outlet of first-stage rotor, second-stage stator, and second-stage rotor. The calculated results are compared with the experimental results. In addition, unsteady condensate mass fractions are numerically visualized and the influence of wakes and secondary vortices to the condensation is discussed.