Effects of free stream turbulence, Reynolds number, and incidence angle on axial turbine cascade performance
A large-scale, low-speed, axial-turbine cascade was designed using a fast interactive design code and tested over a range of turbulence level and incidence angle for Reynolds numbers typically present in gas turbines. In all, 36 test conditions were examined;Testing was done primarily to investigate the profile boundary layer development under different inlet flow conditions. Glue-on hot-film gages and surface flow visualizations were used to identify transition and separation over the airfoil surface. In addition to transition measurements, overall cascade performance was determined from static pressure distributions on the airfoil and detailed five-hole pressure probe and hot-wire probe traverses in an exit plane of the cascade;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 dissipation integral and finite difference analyses.