Boundary-layer suction to eliminate corner separation in cascades of aerofoils

Abstract

Results of a series of experiments are presented in which the corner separation existing at the junction between a cascade sidewall and a moderately loaded compressor blade in cascade was eliminated by means of a boundary-layer suction technique. The relationship which was investigated between suction flow required for controi of the corner separation and the suction slot geometry is also reported. It was found that with careful positioning of the suction slot, bleed flows of less than 0.1 per cent of a half channel mass flow could result in elimination of the separation region. As a result, stagnation pressure profiles at the cascade trailing-edge plane became much more uniform and the high loss core of fluid that would otherwise be shed downstream and hence into succeeding blade rows of a multi-row turbo-machine was eliminated.