叶片进口边位置对小流量工况下离心泵空化特性的影响

为研究叶片进口位置对小流量工况下离心泵空化性能的影响,应用数值计算方法模拟了比转数为81的离心泵的三种模型,得到不同进口边位置的离心泵空化特性,并分析了叶轮内部流场与空化性能曲线的影响关系。结果表明,在小流量工况下,低比转速离心泵叶片进口边位置越靠前,抗空化性能较好,但严重空化后扬程衰减更快,流道直接被空泡堵塞,流道和叶片表面气泡分布较均匀,且气泡充斥流道速度较快,气泡体积分数各流道差值越小。相比较而言,叶片进口位置越靠后,气泡在流道内部和叶片背面分布不均匀,易出现噪声和振动,但在断裂空化状态,气泡并未完全堵塞流道,扬程下降速度较慢。整体来看,在小流量工况下,叶片进口边位置越靠前,离心泵的抗空化性能较好,并通过试验研究验证了模拟结果的可靠性。研究成果可为小流量工况下低比转速离心泵抗空化性能的优化提供参考。

Influence of Blade Inlet Positions on Cavitation Performances of Centrifugal Pump under Low Flow Rate Conditions

In order to study the influence of the impeller inlet position on cavitation performance of centrifugal pump under small flow rate conditions, numerical calculation method was used to simulate three models of centrifugal pump with specific speed of 81. Several cavitation characteristics curves could be obtained when the inlet positions were different. The simulation results show that under low flow rate condition, the position of the impeller inlet was in the front, and its cavitation performance was better. But when the cavitation condition becomes worse, the head in the pump declines faster, and the flow channel was blocked by the cavitation directly. The bubble in the surface of the flow channel and the impeller was more uniform, and the bubble was filled with the flow channel quickly, the difference of the vapour volume fraction in the channels was smaller. When the inlet position of the impeller was in the behind, the bubble was unevenly distributed in the flow channel and the blade-back, which was easily to appear noise and vibration. However, under fracture cavitation state, the bubble did not completely block the flow channel, and the head decreasing rate was slower than the first. Overall, when the flow rate was lower, the more front of the impeller inlet is, the better of cavitation performances in the centrifugal pump is. The simulation results were validated by experimental study, which was found that the simulation results have high reliability. The research has certain reference significance to improve the anti-cavitation performance of low specific speed centrifugal pump under low flow rate condition.