陶瓷泵半开式叶轮前盖板流线对泵性能的影响

Influence of shroud contour of semi-open impeller on hydraulic performance of ceramic centrifugal pump

为了研究陶瓷泵半开式叶轮前盖板流线对泵性能的影响,对叶轮前盖板流线与径向夹角分别为24°,22°,20°,18°,16°,14°,12°共7种方案进行数值计算,得到了各方案的外特性及内部流动情况.通过分析叶轮中液体沿流线从叶轮进口到叶轮出口的平均静压、平均总压及平均相对速度的变化规律,以及从叶轮前盖板流入泵腔间隙与从叶轮外缘所流出的液体流量大小,得到主要结论:随着叶轮前盖板流线与径向夹角减小到一定程度,泵扬程、效率都将随之下降,最高效率点往小流量方向偏移;在叶轮流道中段流入泵腔间隙的液体变多,导致从叶轮外缘流入蜗壳的高能液体变少,加上与在蜗壳内高压驱使下回流入叶轮流道的流体,在流道出口处混合产生的回流及二次流动,是导致泵扬程、效率下降的主要原因.为了验证数值计算的准确性,试制了最优方案3和最差方案7的叶轮,进行外特性试验,并将试验结果与模拟结果对比,发现试验结果与数值计算结果吻合,从而完成了优化设计,可为陶瓷泵半开式叶轮的设计提供一定的参考.

In order to investigate the effect of shroud contour of semi-open impeller on the hydraulic performance of a ceramic pump, seven contours with different angles between the contour and the radial direction, namely 24°, 22°, 20°, 18°, 16°, 14° and 12° are designed and corresponding numerical simulations are carried out, the hydraulic performance as well as flow field in these pumps are obtained. The variations of static pressure, total pressure and relative velocity along streamlines from the inlet to the outlet of impeller, the mass flow rate through the gap between the casing and the contour and the flow rate at the outlet of impeller are analyzed in detail. The simulated results show that as the angle decreases the pump head and total efficiency decline, and the highest efficiency moves towards a low flow rate. The increased leakage through the gap in the mid-portion of contour, reverse and secondary flows at the outlet of impeller are responsible for the reduction in both the head and efficiency. A comparison between the simulated performance curves and tested data for the optimum （20° angle） and poorest （12° angle） cases are made. The simulated results show good agreement with the measurements, in consequence, the optimization design is achieved. The results can provide a reference for the design of shroud contour of semi-open impeller in ceramic centrifugal pumps.