具有叶顶间隙涡轮转子叶栅流动的拓扑及旋涡结构观测

FLOW OBSERVATION OF TOPOLOGICAL AND VORTICAL STRUCTURE IN TURBINE ROTOR CASCADES WITH TIP CLEARANCE

为了了解具有顶部间隙的涡轮转子叶栅流道内及间隙内的流动状况，采用五孔球头测针和五孔微型束状测针分别对叶栅流道和间隙进行了测量，同时对端壁及叶片壁面进行了流动显示，采用拓扑分析方法对显示结果进行了详细分析，探讨了间隙存在时叶栅各种旋涡的形成机理。测量及显示结果表明：由于顶部间隙的存在，在叶栅顶部形成如泄漏涡等复杂的涡系结构，这些涡系之间及它们与上通道涡之间发生强烈的相互作用，明显增大了叶栅的顶部损失；在叶栅尾缘附近存在着部分回流区域。

To know the internal flows and the leakage flow in turbine cascade with tip clearance, detailed measurements were carried out in both the passage and the tip clearance using a five hole Pitot tube. Flow visualization was also carried out on the blade surface and the endwall. In a detailed analysis, a topological method was adopted to describe the visualization, to investigate the mechanism of how various vortices came into being inside the cascade passage. The experimental results show that: (a) Complex vortices such as leakage vortex were found to occur due to the existence of the tip clearance, and losses near the tip of the blade were increased notably because of the interaction of those vortices; (b) Reverse flows were seen near the blade trailing edge.