Experimental investigation on the characteristics and controlling of flow separation inside the centrifugal diffuser
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摘要: 采用接触式探针和粒子图象测速技术(PIV)对导叶式离心泵径向导叶内流场的流动特性进行了研究。基于圆柱形微型三孔探针测试结果对5种流量下导叶的压力恢复能力进行了评估,测孔位置覆盖了导叶进出口截面和主线截面。压力恢复系数的理论值和试验值表明当流量大于导叶设计流量时导叶内产生了较大的静压损失。2C/2D PIV 可视化试验的研究结果表明大流量下导叶叶片压力面发生了流动分离。设计了不同参数组合的涡流发生器来对流动分离现象进行控制,试验研究了6种方案对模型泵大流量工况下性能的影响,获得一组最佳方案,并分析了采用该方案后导叶内的流动特性。Abstract: The flow inside a vane-island diffuser has been studied experimentally using direc-tional probe traverses and time-resolving stereoscopic particle image velocimetry.A classical three holes probe was used covering most of the complete section of the diffuser from hub to shroud and from the pressure to the suction side in order to evaluate the static pressure recovery at five mass flow rates.The difference between theoretical and measurement values of pressure recovery factors shows that the great loss of the static pressure comes from the vaned part when the flow rate is higher than the designed value of the diffuser.Previous 2C-2D PIV measurement results were also given to verify that flow separation area exists on the pressure side under the above two conditions.Six schemes of vortex generators were designed to control the boundary-layer separation.Mean flow characteristics of the scheme obtaining the best pump performance was then analyzed.
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