隔舌对离心泵压力脉动特性及内部流场的影响

摘要

In order to clarify the tongue influence on the internal flow field of centrifugal pump, the external characteristic of centrifugal pump for different tongues was numerically simulated by means of the sliding grid technology. The impact of tongue shape on the efficiency and head was analyzed through experiment. The pressure pulsation characteristics and internal flow field characteristics on the cross sections in pressurized water chamber of the single-tongue and double-tongue were researched under different operating conditions. The results show that double-tongue has an unconspicuous effect on the external characteristics compared to single-tongue;Pressure pulsation frequencies of single-tongue and double-tongue are consistent with the blade passing frequency, and the pressure pulsation amplitude gets more intense near the tongue. Pressure pulsation amplitude on cross sections in pressurized water chamber reduces significantly when the double-tongue is applied, and most of the pressure pulsation frequency is focused on the low frequency. When deviated from the operating point, the pressure pulsation amplitude of single-tongue increases obviously on cross sections. The largest decline rate of the pressure pulsation amplitude reaches 45.5%when the double-tongue is applied. The flow state in internal flow field is better and velocity gradient is more evenly near the tongue, which is more conducive to flow.%为了明确隔舌对离心泵内部流场影响，采用滑移网格技术，对离心泵不同隔舌蜗壳情况下的外特性进行数值模拟，并结合试验分析隔舌形状对离心泵效率和扬程的影响。同时，对不同工况下单隔舌蜗壳、双隔舌蜗壳离心泵压水室各截面上压力脉动特性及其内部流场特性进行研究。研究结果表明：双隔舌蜗壳相比于单隔舌蜗壳对离心泵外特性的影响很小；单隔舌蜗壳、双隔舌蜗壳离心泵压水室各截面的压力脉动频率以叶片通过频率为主，各压力脉动幅值以近隔舌处尤为激烈；采用双隔舌蜗壳时压水室各截面压力脉动幅值明显减小，压力脉动频率多集中在中低频；在偏离设计工况下，单隔舌蜗壳离心泵的某些截面上压力脉动幅值有锐增现象，双隔舌蜗壳时其压力脉动最大降幅达45.5%；双隔舌蜗壳离心泵内部流场流动状态较好，隔舌处速度梯度变化均匀，更利于流体流动。