混流式水泵水轮机驼峰区非定常内流动特性研究

摘要

In order to study the flow field information in hump zone of mixed flow pump turbine under pump working conditions,taking pump turbine model at a pumped storage power station as the research object,the unsteady numerical calculation of the whole flow passage of the model unit was carried out.Based on the experimental data,the flow characteristics at different positions in the flow channel in the hump region were analyzed,the influence of flow rate changes on the flow characteristics in hump zone was discussed.The results showed that when the unit entered the hump zone,the flow rate decreased,the velocity of axial surface of the medium became smaller,and the angle of attack increased,at the same time,the fluid shot toward the back of the blade,flow separation and vortex appeared on the working face.The pressure surface and suction surface of partially fixed guide vanes and movable guide vanes at double row cascade were gradually surrounded by fluid in low velocity zone,the low velocity fluid formed the vortex to block the flow passage,and the energy loss became larger,which led to the decrease of the hydraulic efficiency.These factors were the main causes of the formation of hump zone.%为了研究混流式水泵水轮机在泵工况下驼峰区内的流场信息,以某抽水蓄能电站模型水泵水轮机为研究对象,对模型机组进行了全流道非定常数值计算.结合试验数据,分析了泵工况下驼峰区内流道内不同位置处的流态特征,讨论了流量变化对驼峰区内流动特性的影响.结果表明:当机组进入驼峰区时,流量减小,介质的轴面速度变小,冲角增大,这时流体射向叶片的背面,在工作面上出现流动分离、旋涡现象.双列叶栅处部分固定导叶和活动导叶压力面及吸力面逐渐被低速区流体包围,这些低速流体形成旋涡,阻塞了流道,能量损失变大,导致水力效率降低.这些因素是驼峰区形成的主要原因.