叶顶不同位置喷气对涡轮间隙泄漏流动的影响

Effects of Tip Injection in Different Locations on Clearance Leakage Flow of Turbine

关键词:  叶顶泄漏流  叶顶喷气  叶顶间隙大小  泄漏涡  通道涡

Key words:  Tip leakage flow  Tip injection  Tip clearance size  Leakage vortex  Passage vortex

摘要:

为研究叶顶喷气位置对涡轮间隙泄漏流动的影响，在低速条件下用五孔探针对不同叶顶喷气位置和间隙大小的涡轮叶栅出口进行了详细的测量，并通过数值计算对叶顶间隙三维流场进行了对比，分析叶顶不同位置喷气对三维流场和损失的影响。结果表明:叶顶喷气对泄漏流动的影响随间隙尺寸增大逐渐减弱，小间隙时喷气明显抑制了泄漏流动动能，在降低因泄漏涡所引起损失的同时增加了因通道涡产生的损失，靠近吸力边喷气方案使得泄漏涡损失峰值下降达48.6%，而通道涡损失峰值增加10.4%；大间隙时泄漏流动动能较大，喷气对泄漏流动的影响较小；通过减小泄漏流动动能以削弱泄漏涡与通道涡的相互作用，控制较大三维流动分离的发生，可有效改善流道内间隙侧的流动。

Abstract:

In order to investigate the effects of the tip injection location on tip leakage flow of turbine，the detailed flow-field measurements at cascade outlet are taken with a five-hole probe for the turbine cascade with various tip-injection locations and tip clearance sizes under low speed conditions. The 3D flow fields near the tip region are compared by CFD simulation，and the effects of the tip injection location on the flow fields and losses are analyzed. The results show that the impacts of the blade tip injection on the tip leakage flow are gradually weaken with the increase of clearance size. The tip injection can effectively reduce the leakage flow kinetic energy near the tip region with a small gap. The loss caused by the leakage vortex is reduced and the loss due to the passage vortex increases at the same time. The injection near the suction side decreases the leakage vortex loss by 48.6% but the peak value of loss due to the passage vortex increases by 10.4%. The kinetic energy of leakage flow increases with the augment of the clearance size and tip injection has a negligible effect on the leakage flow. By reducing the leakage flow kinetic energy to weaken the interaction between leakage vortex and passage vortex，and control the large 3D flow separation to occur，it can effectively improve the performance of flow near the clearance.