口环间隙变化对离心泵性能的影响研究

Study on effects of wear-rings clearance modifications on performance of centrifugal pump

基于雷诺时均N-S方程组和RNG k-ε湍流模型,采用三种口环间隙变化方案对离心泵进行了数值模拟:只改变前口环间隙,只改变后口环间隙,同时改变前后口环间隙;与试验结果的对比表明,计算结果与试验结果吻合良好,在可接受的误差范围内;三种间隙变化方案中,以前口环间隙的改变对离心泵性能的影响最大。口环间隙的改变不仅会对离心泵的容积损失产生影响,而且会影响离心泵的外特性。从流场结构看,间隙变化的影响主要集中在前后腔体及间隙出口处;随着间隙增大,腔体处低压区向蜗室方向扩大,而间隙出口处高压区也有扩大趋势。由间隙增大导致的泵进口压力升高,在大流量工况下可以提高泵的空化性能。

Based on the Reynolds time-averaged N-S equations and a RNG k-ε turbulence model, a centrifugal pump was simulated for three schemes of wear-rings clearance modification, i.e. only front wear-ring clearance modified, only rear wear-ring clearance modified, and both clearances modified. Comparison shows a good agreement of the numerical results with experiments. Among the three schemes, the front clearance change has the most significant influence on the performance of centrifugal pump. A change in wear-ring clearances not only has an effect on volumetric loss, but on pump performance. A flow structure analysis shows that the modification effects manifest in the front and rear chambers, also in the outlet of clearances, while insignificant in other sections of the pump. As the clearance widens, a low pressure area in the chamber tends to expand toward the volute and a high-pressure zone near the clearance outlet has a tendency to expand toward the impeller inlet. This further causes an increase in static pressure at the pump inlet and a consequent improvement on the cavitation performance of the pump in high flow conditions.