蜗壳回流孔对自吸泵性能的影响

摘要

回流孔在自吸泵中通过液体回流蜗壳的方式达到改善自吸性能的目的，其位置和面积大小对自吸性能和效率有着显著影响。利用计算流体力学分析方法对带回流孔的自吸泵内部流动进行数值模拟，研究回流孔附近的流动特性，分析不同回流孔位置和面积对内部流动和泵性能的影响。结果显示，基于内流模拟预测的自吸泵性能与试验结果趋势吻合。在设计工况下，增大回流孔面积可使回流蜗壳的流量增大，在不降低泵性能的情况下明显改善泵的自吸性能；在大流量工况下，回流孔面积的增大导致蜗壳到气液分离室的泄露，从而带来较大的容积损失。回流孔在环向的位置主要对蜗壳内外压差产生影响，随着回流孔向隔舌靠近，蜗壳与气液分离室的压差逐渐变大，从蜗壳到气液分离室的泄漏损失增大，泵的效率降低。因此，对于特定的自吸泵，存在一个最佳的回流孔开孔面积和位置。%Reflux hole helps self‐priming pumps to improve self‐priming performance w hen the re‐flux liquid flow s into volute .Its position and area have a great influence on the self‐priming capa‐bility and efficiency of the pump .The internal flow field of the self‐priming pump was numerical‐ly simulated with the CFD method ,to study the flow characteristics nearby the reflux hole and analyze the impact of the position and area of the reflux hole on the internal flow as well as the pump performance . The simulation results showed that the tendencies of simulation results matched with the experimental data .When the pump was operated at its design point ,the reflux flow rate increased with the area of the reflux hole and consequently the self‐priming capability was improved without suppressing the pump performance .When the flow rate was larger than the nominal flow rate ,the increase of the area of the reflux hole leaded to the leakage that flowed from the volute to liquid storage chamber ,which caused greater volume loss .The position of re‐flux hole had influence on the pressure difference between the inside and outsider of the volute . The position of reflux hole was closer to the tongue ,the pressure difference between the volute and the liquid separating chamber was bigger .And the leakage flowed from the volute into liquid storage through reflux hole was larger ,which reduced the efficiency of the pump .So there is an optimal area and position of reflux hole for a specific self‐priming pump .