AERODYNAMIC PERFORMANCE OF ULTRA-HIGHLY LOADED AXIAL TURBINE CASCADE : INFLUENCES OF TIP CLEARANCE AND BLADE PROFILE

In this study, the aerodynamic performances of three types of ultra-highly loaded axial turbine cascade (UHLTC) with the turning angle of 160 degree were assessed by using the small annular turbine cascade test rig. The profiles of three types of UHLTC are different in the length along the blade suction surface which is related to the blade maximum thickness. In addition, in the measurements of the aerodynamic performances of these UHLTC, the tip clearance size was set to 2% and 3% of the passage height. The experimental results showed that the decrease of the size of tip clearance enhanced the torque performance and the turbine efficiency because of the reduction of aerodynamic loss in every type of UHLTC. Moreover, the increase of the blade maximum thickness by the increase of the length of blade suction surface more effectively reduced the aerodynamic loss