ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

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 18m3/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 0.1QBEP. 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.