回流孔对外混式自吸离心泵内部流动特性的影响

回流孔在外混式自吸离心泵的结构中有着特殊的作用,是影响自吸排污泵性能的重要因素之一。为了研究回流孔对自吸排污泵内部流动特性的影响,以具有不同回流孔面积的ZW型高效自吸排污泵为研究对象,对泵内部流场进行数值模拟。研究结果表明,回流孔的存在对泵内流动特性和性能都有一定的影响,泵内会形成较明显的环形流动,扬程和效率显著降低。不同工况下回流孔两侧(即气液分离室和蜗壳)压力分布发生规律性变化,回流孔处的流动状态也随之发生变化;随回流孔面积变化将引起回流孔两侧压差及回流量的变化,最终反映为外特性的变化。

Effect of reflux hole on internal flow characteristics of outer recirculation self-priming centrifugal pumps

Due to its special role in adjusting internal flow structure, a reflux hole is a key device that affects the performance of outer recirculation self-priming centrifugal pumps. To examine its effects, the internal flows have been numerically simulated in this study for an efficient self-priming sewage pump of ZW type with a reflux hole connecting the gas-liquid separation chamber to the volute. Results show that this reflux hole had a significant effect on the internal flow and pump performance. It produced a circular flow and a considerable increase in head loss and hence reduced pumping lift significantly. As the pump flow rate was varied, the pressure distribution at the chamber and volute sides of the hole was changed in a regular way, and the flow patterns near the hole inlet and outlet also changed. A change in the hole cross-sectional area caused a change in the pressure drop from the hole inlet to outlet and a change in the hole flow rate, thus modifying the external characteristics of the pump.