On the performance of a cascade of turbine rotor tip section blading in wet steam Part 2: Surface pressure distributions

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 vapour. Formation and subsequent behaviour of the liquid lowers the performance of turbine wet stages. To produce turbine nucleating and wet flow conditions realistically requires a supply of supercooled steam which can be achieved under blow-down conditions by the equipment employed. To obtain wet steam, the supercooled vapour generated is passed through a venturi before admission to the cascade. To evaluate the influence of droplet size two separate Venturis have been used in the investigation. The performance of a cascade of rotor tip section blading in wet steam has been studied. This paper is the second of a set and describes the results of the surface pressure measurements.