The Effect of Profile Contouring on Secondary Flow Structures in Low Pressure Turbines

Abstract

Research aimed at reducing weight and improving efficiency of low pressure turbines has led to the design of highly loaded blades. These blades typically have higher endwall losses due to increased blade spacing and higher pressure gradients that strengthen secondary vortex structures. The present study focuses on the effects of profile contouring spanwise blade shape variations used to manipulate dominant vortex structures such as the passage vortex and suction side horseshoe vortex. With the goal of improved efficiency from reducing total pressure loss across the passage, the study aims to determine the effect of various profile contours on the secondary flow field and underlying physics. Experiments were conducted in the Air Force Research Laboratory Low Speed Wind Tunnel Facility at Wright-Patterson Air Force Base. Data includes surveys of total pressure, velocity, and surface flow visualizations through the passage. Measurements are focused on the aft portion of the passage where the passage vortex interacts with the blade suction surface. These measurements confirmed correlations between losses and Reynolds shear stress components. Deformation work is also seen to correlate well with total pressure loss.