Experimental and Computational Study on the Effect of Pressure Surface Camber on the Aerodynamic Performance of Variable-Speed Turbine Blades

Improving the adaptability of variable-speed turbine blades to varying incidence angles by optimizing blade profile camber design is an effective approach to achieving the efficient operation over a wide range of incidence angles and enhancing the performance of variable-speed turbine. This paper presents cascade experiments and numerical studies of variable-speed turbine blades with three different pressure surface profiles over a wide range of incidence angles. The research results indicate that at positive incidence angles, the sharp increase in losses primarily occurs at the front and middle regions of the suction surface, with a rapid rise that is difficult to optimize; at negative incidence angles, the sharp increase in losses primarily occurs at the front and middle regions of the pressure surface. At extreme negative incidence angles (-30°), the incremental blade profile loss caused by the front and middle parts of the blade pressure surface accounts for more than 85% of the total blade profile loss increment. The camber of the blade pressure surface has a significant impact on the blade pressure surface loss. By appropriately reducing the camber of the blade pressure surface, flow separation at negative incidence angles can be mitigated, thereby reducing the profile loss. However, reducing the camber of the blade pressure surface will also lead to an increase in blade profile loss at the design point. Overall, a proper reduction in the camber of the blade pressure surface can expand the range of low blade profile loss incidence angles for the blade.