端壁凹坑位置对跨声速缩放型流道涡轮叶栅流动影响研究

Effect of Endwall Dimple on Transonic Turbine Cascade with Scaled Flow Channel

本文采用CFD数值模拟方法研究非光滑端壁对涡轮叶栅的影响。设计端壁凹坑三种方案,通过模拟结果的对比分析,讨论不同位置端壁凹坑对叶栅流道内分离损失的影响。端壁凹坑选取深度为0.2 mm,深宽比为0.25的3排凹坑,该凹坑分别被布置在18%~30%,40%~52%,65%~77%的弦长位置。讨论研究结果发现,相对于原型跨声速叶栅端壁位置较强的横向二次流动,凹坑使流体横向迁移减弱,阻止了端壁低能流体沿径向抬升,延缓涡结构的发展,进而降低了叶栅流道损失。除此之外,凹坑对降低激波接触点附近的流动也具有减损效果。对比所有方案,18%~30%弦长处的凹坑作用效果最为明显,流动损失降低3.90%。

CFD numerical simulation method is used to study the influence of non-smooth endwall on turbine cascade in this paper.Three dimples are designed,and the influence of endwall dimples at different positions on the separation loss in cascade passage is discussed by comparing and analyzing the simulation results.Three rows of dimples with a depth of 0.2 mm and an aspect ratio of 0.25 were selected,and the dimples were distributed at the chord lengths of 18%-30%,40%-52%and 65%-77%respectively.The results show that compared with the strong transverse secondary flow at the endwall position of the transonic turbine cascade,the dimples weaken the lateral migration of the fluid,prevent the radial uplift of the endwall low-energy fluid,delay the development of vortex structure,and then reduce the flow loss of the cascade.In addition,dimples can also reduce the flow near the shock contact point.Compared with all schemes,the dimples with 18%to 30%chord length have the most obvious effect and the flow loss is reduced by 3.90%.