On the Performance of a Cascade of Turbine Rotor Tip Section Blading in Nucleating Steam: Part 1: Surface Pressure Distributions

During the course of expansion in turbines, steam first supercools and then nucleates to become a two-phase mixture. Formation and subsequent behaviour of the liquid lower the performance of turbine wet stages. To reproduce turbine nucleating and wet flow conditions requires a supply of supercooled steam which can be achieved under blow-down conditions by the equipment employed. The performance of a cascade of rotor tip section blading in nucleating steam has been studied. The results of the surface pressure measurements are described in the paper.