大转角涡轮叶栅复合弯曲定性分析与应用验证

The influence of the compound bowing design was discussed based on theoretical analysis and verified by numerical simulations based on a highly-loaded linear turbine cascade with a large turning angle. The compound bowing design applied local positive bowing design near the endwall region on the suction surface of a negative bowed blade, so the blade presented negative bowed pressure surface and compound bowed suction surface. Generally, the study showed that the compound bowed suction surface could improve the flow field by adjusting the static pressure distribution on suction surface and the deflection of the cross flow. In detail, the negative bowed suction surface could suppress the development of the boundary layer and the shedding vortex near the mid-span, while the positive bowed suction surface could suppress the development of the boundary layer and the Corner Vortex near the endwall. Moreover, the positive bowed suction surface near the endwall could further suppress the passage vortex and the corner vortex by adjusting the deflection of the cross flow and reducing the interaction between the cross flow and boundary layer near the suction surface. As a result, it showed that the compound bowed cascade could lead to a loss coefficient reduction about 65.5% better than the negative bowed one in this study.