具有叶顶间隙的涡轮正弯叶栅流场的拓扑与旋涡结构

为进一步揭示在具有间隙的涡轮叶栅中叶片正弯降低泄漏损失的机理，采用微型束状与球头五孔测针详细测量了直叶栅和正弯叶栅间隙内和诸横截面流场听气动参数，并对壁面进行了墨迹显示。根据测量与显示结果，应用拓扑学原理分析了壁面与横截面流动的拓扑结构，推测出叶栅内流场的旋涡结构。分析结果表明，在直叶栅中存在着七条分离线与七大集中涡系，它们分别为上端壁叶顶进口吸力边与压力边马蹄涡，泄漏损失的机理，下端壁进口边马蹄

Topological and Vortex Structure the Flow Field of the Positively Curved Cascade with the Tip Clearance

In order to further reveal the mechanism that blade positively curving reduces the energy losses,the aerodynamic parameters in the flow fields on intermediate surfaces and cross sections of straight and positively curved cascades are measured in detail by means of five hole microhunch shaped and microspherical probes,and the flow patterns surrounding the wall(including both upper and lower endwalls as well as blade surfaces) are visuazated with an ink trace technology.On basis of results of the measurements and viualizations,appling the topology principle has analysed te topological structure on the wall surfaces and the cross section,and infered the vortex structuers in the flow fields of the cascades.The results of the analysis show that there are seven separated lines and seven concentrated vortices in the straight cascade.Those vortices are inlet suction side and pressure side horseshoe vortices respectively near the top endwall,the leakage vortex,the secondary vortex,the lower endwall inlet side horseshoe vortex,as well as upper and lower passage vortices.In comparison with these of the straight cascade the blade positively curving reduces the quantity of the critical points,eliminates the upper passage vortex,and transform the closed separated flow of the secondary vortex along the blade tip suction side into the open separated flow.