中文摘要：

以一台比转数为74的离心泵为研究对象,首先通过外特性试验发现当流量约低于18 m^3/h后,泵的扬程随流量变化非常小,然后采用PIV技术探索了该扬程曲线下叶轮流道内不稳定流动涡的发生、发展规律。试验结果表明：不稳定流动在0.6QBEP工况开始产生,直到0.4QBEP工况得到发展,最后在0.1QBEP时几乎扩展到整个叶轮流道;叶轮旋转过程中,靠近蜗壳隔舌处的叶轮流道内流动最不稳定,也是最先出现分离涡的流道;随着流量的降低,附着于叶片工作面的分离涡逐渐增多、汇聚,不断发展的漩涡向流道出口移动的同时,也偏向于流道中心。

英文摘要：

A centrifugal pump with specific speed of 74 was studied. Hydraulic performance test was done firstly, and the result showed that the head changed little with the flow reduced when flow was less than 18 m3/h. In order to research the flow instabilities under the above H- Q curve, PIV technique was adopted to discover the onset and development rule of unstable vortex within the impeller. The results showed that the flow was separated at 0.6QBEp, developed at 0.4QBEp and spread almost the whole impeller passage at 0.1QDEP. In addition, flow in the passage near the tongue was the most unstable, and the vortex was also occurred in this passage firstly by comparing with rest of passages. With the flow rate decreasing, the vortex on the pressure side was increased and converged to a large-size vortex which spread to the outlet of passage and moved to the centre area of the passage in the end.