The Effect of End-Wall Profiling on Secondary Flow and Loss Development in a Turbine Cascade

Abstract

The potential for loss reduction by using non-axisymmetric end-wall profiling has been demonstrated in the so called “Durham” cascade (Hartland et al [1]) and in a turbine representative rig (Brennan et al [2] and Rose et al [3]). This paper aim to enhance the understanding of end-wall profiling. It describes detailed measurements from upstream to downstream through the Durham cascade. The measurements cover the profiled end-wall used by Hartland, a second generation end-wall design (Gregory-Smith et. al. [4]) and the planar reference case. Considerable effort has gone into refining the measurement technique used in the cascade and new results are presented for traverses downstream which capture more accurately the flow near the end-wall. These measurements show the development of loss and secondary flow throughout the blade row. It is shown that end-wall profiling has a dramatic effect on the flow patterns in the early part of the blade row which then translates to a loss reduction later in the blade row. Comparison with CFD results aids the understanding of the role of the reduced horseshoe vortex in this process.