蜗壳隔舌半径对离心泵性能及水力载荷特性的影响

为研究蜗壳隔舌半径对离心泵性能及水力载荷特性的影响,针对同一叶轮匹配5种不同隔舌半径的离心泵进行非定常数值计算.通过计算获得了不同泵的水力性能、压力脉动特征、叶片载荷及叶轮上的径向力分布,并且与试验结果进行对比分析,验证了采用的数值计算方法具有较高的正确性.研究结果表明:隔舌半径对扬程的影响较小,随隔舌半径的增大,各工况下效率呈先增大后减小的趋势;当隔舌与基圆半径之比TR取值为0.09~0.24时,叶片工作面与背面的载荷差值有最小值,即此时叶片受力沿进口至出口的变化最小;随着隔舌半径的增大,泵内的压力脉动水平逐渐降低,TR=0.03时,叶频处的压力脉动幅值约为TR=0.3时的2倍;隔舌半径对叶轮径向力的大小影响显著,在设计工况下,径向力随隔舌半径的增大而增大,且TR=0.3时的径向力约为TR=0.03时的2.5倍.

Effects of tongue tip radius on performance and hydrodynamic load characteristics in centrifugal pump

In order to investigate effects of volute tongue tip radius on performance and hydraulic load characteristics, unsteady flow fields in a centrifugal pump with the same impeller but different volutes in five tongue tip radii were simulated numerically. The hydraulic performance, pressure pulsation, blade loading and radial thrust on the impeller were acquired and analysed, and the predicted perfor-mance was compared with the experiment results, showing the numerical methods adopted in the paper were in a better accuracy. The results showed that the tip radius had a little effect on the hydraulic performance, but the best hydraulic efficiency could be achieved at a certain tip radius. When the dimensionless tip radius TR(tip radius-to-base circle radius ratio)was in a range of 0.09-0.24, the loa-ding across the blade pressure side and suction side was the minimum, i.e. the force acting on a blade exhibited the least variation from the leading to trailing edges. With increasing TR, the pressure fluctuation level in the pump reduced gradually, particularly the pressure amplitude at TR=0.03 was about 2 times the amplitude at TR=0.3 for blade passing frequency. The tip radius has a significant effect on impeller radial thrust. At the nominal flow rate, the radial thrust increased with increasing tip ra-dius, and at TR=0.3 the thrust was about 2.5 times the thrust at TR=0.03. 