Leading Edge Modification Effects on Turbine Cascade Endwall Loss

Abstract

Experimental results are presented which provide area-averaged total pressure loss coefficient measurements for four different turbine airfoil leading edge configurations. A baseline (Langston) configuration, two leading edge bulbs, and a leading edge fillet were tested in a large-scale, low aspect ratio, high turning linear cascade. Results show that both the small bulb and fillet geometries each reduced area averaged total loss by 8%, while the large bulb exhibited a slight increase in total loss. Contour plots for all geometries are presented and the major differences between each are discussed. Through investigation of pitch averaged loss profiles it is found that the area of greatest reduction differs between the small bulb and fillet, leading to the possibility that the mechanisms through which each is affecting the flow may be different. This provides hope that the best features of each may potentially be combined to determine an optimum shape for secondary flow loss reduction.