U型槽对高负荷低压涡轮叶型攻角特性影响

Effect of U-grooves on high-lift low pressure turbine profile's incidence characteristics

以某高负荷低压涡轮叶型为研究对象,分析了该叶型在低雷诺数下的攻角特性,并应用了表面嵌壁式U形槽的被动控制方法来提高该叶型的攻角裕度.数值模拟的结果表明:相比较大的正攻角流动状况,叶型较大的负攻角并不会引起吸力面大的流动分离,从而减小了叶型损失;表面嵌壁式U型槽通过推迟分离、加速再附来减小分离泡甚至减小湍流湿面积,从而降低叶型损失;表面嵌壁式U型槽能否提高该叶型的攻角裕度与开槽位置和深度有关系,在±15°攻角范围内72%轴向弦长位置处开槽明显的降低了叶型损失而开槽深度为0.40mm时叶型损失最小.

The high-lift low pressure turbine blade profile incidence characteristics under low Reynolds number were investigated. The modification used recessed U-grooves to im- prove the profiles~ incidence margin. The numerical simulations suggest that compared with high incidence flow condition, lower incidence does not induce large separation which ap- pears on the suction surface of the profile and hence lessens profile loss. The recessed U- grooves delay the separation location, accelerate reattach location, decrease the turbulent wetted area, thereby the separation bubble is suppressed and the profile loss decreases. Whether or not the recessed U-grooves can improve the incidence margin is related to the depth and location of the U-grooves. With±15 incidence degrees, the U-grooves located in 72% axial chord length showed lower profile loss, and when the depth was 0. 40mm the pro- file loss was the lowest.