Effect of Combined Boundary Layer Fences on Turbine Secondary Flow and Losses

Abstract

In an attempt to improve the aerodynamic performance of axial-flow turbines, boundary layer fences were attached to the blade suction surfaces and the endwalls of a rectilinear turbine cascade. Measurements of three-dimensional flow and total pressure losses were carried out at various protruding heights and locations of the combined fences. The best combination resulted in a considerable attenuation of secondary flow, an improvement on the spanwise distribution of outlet flow angles, and a 26 percent reduction in the gross loss of total pressure. This reduction of loss was larger than either the maximum reduction with the blade fences only or the maximum reduction with the endwall fences only. The best combination was distinguished from a straightforward combination of the optimum blade fences and the optimum endwall fences .