固相浓度对旋流泵内循环流动结构的影响

为研究固相体积分数对旋流泵内部循环流结构的影响,以150WX-200-20型旋流泵为研究对象,基于流体动力学理论,采用Eulerian双流体模型,以体积分数为10%~35%的固相与清水的6种混合流体为介质进行数值模拟.对比分析旋流泵内流场的流线变化规律,研究不同固相体积分数时,在泵内以轴为中心阵列的4个1/4截面上涡结构的涡核位置及形状变化规律.结果表明,固液两相流时,在叶轮旋转作用下旋流泵内形成一组主循环流Ⅰ和一组次循环流Ⅱ,主循环流传递至进口处的流体形成另一组次循环流Ⅲ,固相的介入会减弱旋涡的强度并抑制循环流Ⅱ截面涡结构面积的扩展,提出一种了旋流泵流动模型;固相体积分数增大时,主循环流在无叶腔内变化范围随流量的增大缩小,在无叶腔内,涡核效率均随流量增大而增大,而当涡核进入叶轮域被破坏后,泵效率降低.在高效点1.2Q_d,固相体积分数越大,涡核与轴线距离越小;在无叶腔内,表征截面上涡结构的形状系数e的值在高效点1.2Q_d处均较大,涡结构的形状均较扁.

Effect of solid concentration on circulation flow and hydralic characteristics in vortex pump

In order to study the effect of solid concentration on the structure of the circulation flow in the vortex pump, the 150WX-200-20 vortex pump was taken as the research object. The theory of fluid dynamics and the Eulerian two-fluid model was used. Six mixed fluid of solid and water were used as the flowing medium. The solid concentration was changed from 10% to 35%. Numerical simulation analysis was performed on the vortex pump. The variation rules of the streamline of the flow field in the vortex pump were compared and analyzed. The vortex core positions and shapes of the vortex structure on four 1/4 cross-section arrays with the axis as the center in the pump were studied at different concentrations. The results show that in solid-liquid two-phase flow, a set of main circulation flow I and a set of secondary circulation flow Ⅱ are formed in the vortex pump under the action of the impeller. The main circulation flow transfers the fluid acting at the inlet to form another set of secondary circulation flow Ⅲ. The intervention of solids will weaken the strength of the vortex and inhibit the expansion of the vortex structure area of the cross-section Ⅱ. A flow model of the vortex pump is proposed. With the increase of solid concentration, the variation range of the main circulation flow with the increase of flow in the non-leaf cavity is reduced. Under the operating conditions of the vortex core in the non-leaf cavity, the efficiency increases with the increase of the flow. After the flow increases into the impeller domain, the pump efficiency decreases. At the high efficiency point 1.2Q_d, the larger the solid concentration, the smaller the distance between the vortex core and the axis. Under the operating conditions of the vortex core in the non-leaf cavity, the value of the shape coefficient of the vortex structure on the cross section is larger at the high-efficiency point 1.2Q_d, and the shape of the vortex structure is relatively flat.