低比转数排污泵数值计算与实验

结合数值计算与PIV实验手段,对一改造过的比转数ns =60的潜水排污泵蜗壳内部流动进行了研究。采用六面体结构化网格对其进行全流场数值计算,计算结果表明,由于口环泄漏导致该区域附近的湍动能最大,且设计工况下蜗壳内部湍动能要大于叶轮内部。另外,通过外特性实验结果、PIV测试结果与CFD数值计算的对比发现,二者能够较好地吻合,验证了数值计算的正确性,并得出以下结论：受叶轮出口绝对速度与圆周方向夹角随流量增加而变大的影响,在0.6Qopt 和Qopt 流量下第8断面内的流体一部分再次通过蜗壳进入第1断面内,导致蜗壳隔舌与蜗壳进口之间的速度较高,在该处造成较大的速度梯度;而在1.4 Qopt 工况下此现象消失,蜗壳第8断面附近的速度最高,速度梯度较大;并且在大流量1.4Qopt 下蜗壳第1断面与第5断面之间能够明显地看出3个从叶轮出口射流出来的高速尾迹区域。

Numerical Simulation and Experimental Research on Low-specific-speed Sewage Pump

After structural modification of a submersible sewage pump with a specific speed (ns ) of 60, an experimental study combined with numerical simulation and PIV measurements was carried out in order to analyze the internal flow of the volute. The calculated region was spitted by structure grid and the numerical simulation of whole flow field was performed. The results showed that due to the mouth ring leakage, turbulent kinetic energy was the greatest near this region, and the turbulent kinetic energy in the volute was greater than one in the impeller at the design condition. In addition, comparisons between experiment results of pump performance, PIV test results and CFD computations showed that they were in good agreement, which also validated the numerical result. At last the following conclusions were obtained: affected by the fact that the angle between relative velocity and circumferential direction was became larger with the increasing of the flow rate, when the flow rate was 0.6 Qopt and Qopt , partial fluid in the eighth section return to the first section through the volute, so, there were great velocity and velocity gradient in the region between the tongue and volute inlet. For 1.4 Qopt , this phenomenon disappeared, and at the region near the eighth section, its velocity was maximum, which leaded to a larger velocity gradient. Besides, at the flow rate of 1.4 Qopt , in the region between the first section and the fifth section, three high-speed wake regions from the impeller outlet could be obviously observed.