叶轮出口宽度对离心泵内部非定常性能的影响

Influence of Impeller Outlet Width on Unsteady Performance inside Centrifugal Pump

为了研究多工况下不同叶轮出口宽度对离心泵非定常性能的影响,基于RNG k-ε湍流模型对叶轮出口宽度分别为11、12、13、14和15 mm的离心泵模型分别在0.8Qd、1.0Qd、1.2Qd三种流量工况下进行定常和非定常的数值模拟,得到离心泵的外特性曲线、内部流场以及压力脉动特性,并进行对比分析。结果表明:离心泵的扬程随叶轮出口宽度的增加而增加,存在一个最佳的叶轮出口宽度使其效率最佳且最佳效率点向大流量点偏移;随着叶轮出口宽度的增加,叶轮截面的最大压力值呈先增加后减小再增加的趋势,小流量工况下的湍动能较大区域随叶轮出口宽度的增加由叶轮流道出口向叶轮流道中间发展;各监测点的压力脉动均呈周期性变化,压力系数随流量的增大而增大,在设计和大流量工况下,当叶轮出口宽度为13 mm时压力脉动幅值明显小于其他型式的叶轮,因此适当增大叶轮的出口宽度有利于减小离心泵的压力脉动、提高其性能。

In order to study the effect of different impeller outlet width on the unsteady performance of centrifugal pumps under multiple operating conditions,the centrifugal pump models with impeller outlet widths of 11 mm,12 mm,13 mm,14 mm and 15 mm respectively were built based on the RNG k-ε turbulence model,and the steady and unsteady numerical simulations were carried out under the three flow conditions of 0.8Qd,1.0Qd and 1.2Qd.The external characteristic curve,internal flow field and pressure pulsation characteristics of the centrifugal pump were obtained and compared.The results showed: the lift of the centrifugal pump increases with the increase of the width of the impeller outlet.There is an optimal impeller outlet width that optimizes the efficiency,and the best efficiency point shifts to the large flow point.As the impeller outlet width increases,the pressure in the impeller section increases first,then decreases and then increases again.Under small flow conditions,the area of relatively large turbulent kinetic energy develops from the impeller flow passage outlet to the impeller flow passage with the increase of the impeller outlet width.The pressure pulsation of each monitoring point changes periodically and the pressure coefficient increases with the increase of flow rate.Under the design and large flow conditions,the pressure pulsation amplitude is clearly smaller than other types of impeller when the impeller outlet width is 13 mm.Therefore,appropriately increasing the outlet width of the impeller is beneficial to reduce the pressure pulsation of the centrifugal pump and improve its performance.These research results are expected to serve as reference for the optimal design of the centrifugal pump impeller.