Experimental and Numerical Study of Pressure Ratio Distributions For Transonic Condensing Flow Through a Stationary Stator Blades Cascade

Abstract

In the course of expansion in turbines steam nucleates to become a two phase mixture, the liquid consisting of a very large number of extremely small droplets carried by the vapor. Formation and subsequent behavior of the liquid lowers the performance of turbine wet stages. The calculations were carried out assuming that the flow is two dimensional, compressible, turbulent and viscous. A classical homogenous nucleation model applied for the mass transfer in the transonic conditions. The aim of the present study is investigation of outlet pressure effect on second phase generation in a steam turbine. The conditions at inlet to the test section were varied from a wet equilibrium to a superheated state by changing the cascade exit pressure. Experimentally it was found that the most important influence of rapid condensation on the pressure distribution is occurred on the suction surface and it grows by decreasing the downstream pressure. Pressure profiles around the blades are compared with the experimental data and good agreement is observed. The maximum and minimum of droplet numbers have been achieved and nucleation zone has been specified in blade passage.