Effect of Free-Stream Turbulence, Reynolds Number, and Incidence on Axial Turbine Cascade Performance

Abstract

A large-scale, low-speed, axial turbine cascade designed for high-loading and high-turning was tested over a range of Reynolds number, turbulence level, and incidence angle. End wall suction was applied to provide two-dimensional flow over a large spanwise region of the airfoil. In all, thirty-six test conditions were examined. Overall cascade performance including mass-averaged loss coefficients at each test flow condition was determined from detailed five-hole pressure probe traverses in an exit plane of the cascade. In addition, using glue-on hot-film gages and surface oil-flow visualizations, transition and/or separation was identified over the suction surface of the airfoil. The measured transition start and end points were compared against predictions using existing transition models. Also, the measured losses were compared against predicted losses from boundary layer calculations based on finite difference analysis.