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对具有叶顶间隙的直叶栅和正、反弯三套涡轮叶栅进行了实验测量,研究在较大间隙(0.036)下,气流冲角和叶片弯曲对叶顶泄漏流动的影响。根据壁面流动的墨迹显示,应用拓扑学原理,分析了叶片表面和上、下端壁的拓扑结构,指出当气流冲角由0°增至20°时,与零冲角下的同类叶栅相比较,鞍点的位置均移向上游,分离区的范围在沿流向和垂直流向的方向上扩大,上、下通道涡分离线向叶展中部爬升。在冲角为零以及20°的情况下,叶片正弯均消除了上通道涡,这一方面减少了壁面流场中奇点和分离线的数量,较大地降低了上通道涡与泄漏涡的相互作用损失,另一方面强化了端壁横流对泄漏流动的封堵作用,有利于降低相对漏气量。
Three straight turbine cascades with positive tip clearance and three sets of positive and negative bend turbine cascades were measured to study the effect of airflow angle and blade curvature on tip leakage at large clearance (0.036). According to the ink flowing on the wall surface, the topological structure of the blade surface and the upper and lower end walls were analyzed by using topological principle. It was pointed out that when the angle of attack increased from 0 ° to 20 °, compared with the similar cascade at zero angle of attack , The positions of the saddle points move to the upstream, the range of the separation zone expands along the flow direction and the vertical flow direction, and the vortex separation lines of the upper and lower channels climb to the middle of the leaf blade. When the angle of attack is zero and 20 °, the positive vortex of the blade eliminates the upper vortex. On the one hand, the number of singular points and separation lines in the wall flow field is reduced, and the vortex of the upper channel and the leakage vortex are greatly reduced Interaction loss, on the other hand to strengthen the cross-flow of the end wall of the plugging effect of leakage flow, help to reduce the relative amount of leakage.