Wake characteristics of a steam turbine rotor tip linear cascade blade in subsonic flow

Abstract

Experimental investigations have been carried out on a steam turbine rotor tip linear cascade to determine the effect of Mach number on the flow and total pressure losses at zero degree of incidence. Static pressure distribution on the blade surfaces have been measured. Exit flow survey has been carried out using a precalibrated five hole probe at the corresponding Mach number. The exit Mach number has been varied from 0.27 to 0.52. The effect of Mach number on various parameters such as lift coefficient, total pressure loss coefficient, mass averaged exit flow parameters and wake parameters has been found to be small. Wake self-similarity has been observed for velocity profiles at all Mach numbers. The wake half widths and integral thicknesses increase slowly with Mach number. Shape factors are in the range of 1.1 to 1.4, indicating turbulent boundary layers on the suction and pressure surfaces of the blade.