Non-axisymmetric turbine end wall profiling

Abstract

A design method for profiling the end wall to reduce secondary flow has been reported previously. A profile has been tested in the Durham Linear Cascade and the results confirmed the design method. This paper describes the design and testing of a second-generation end wall, where the profiling is more suited to a real turbine. The new end wall has been tested in the linear cascade and a comprehensive set of measurements have been taken. These include traverses of the flow field upstream and downstream of the blade row, surface static pressure distributions on the end wall and flow visualization. Comparisons have been made with the results with a planar end wall and the earlier profiled end wall. Observed reductions in exit angle deviations are even greater than for the first design, although the loss reduction is not as great. The results verify the design, confirming profiled end walls as a means of reducing secondary flow, kinetic energy and loss. Overall an improved understanding of the effects of end wall profiling has been obtained although further work is required in this area.