立式轴流泵装置进口导水锥支架对马鞍区性能影响研究

The Impact of the Inlet Water Guide Cone Bracket on Function of the Saddle Zone in Vertical Axial Flow Pump

【目的】研究进口导水锥支架对"马鞍区"和设计流量工况下立式轴流泵装置水力性能以及水泵内部流场的影响。【方法】基于RANS方程和SST k-ω湍流模型进行三维计算,选择立式轴流泵装置进行有无进口导水锥支架方案的对比分析,通过模型试验验证了数值计算的可靠性。【结果】小流量工况下,无进口导水锥支架方案立式轴流泵装置进水流道出口出现流动回流,形成大范围回流漩涡,造成进水流道堵塞,引起大量低频压力脉动,并产生能量损失,致使扬程突降,出现马鞍区。有进口导水锥支架方案可以有效抑制回流漩涡的范围和强度,降低低频压力脉动,提高泵装置稳定性。马鞍区最低点扬程上升5.5%,明显消除马鞍形。设计流量工况,进口导水锥支架的设置增加了叶片做功能力,抵消了支架的部分水力损失,使得扬程下降较小,约1.3%,内流场较为均匀。【结论】进口导水锥支架在工程应用中具备改善立式轴流泵装置马鞍区的巨大潜力。

【Objective】The purpose of this paper is to study the influence of the impeller guide cone bracket on hydraulic performance of the saddle zone in vertical axial flow pump,as well as the associated water flow field in it in order to help pump design.【Method】The analysis was based on numerical modelling;three-dimensional turbulent flow in the pump was simulated based on the RANS equation and the SST k-ωturbulence model;we compared the results obtained with and without the guide cone bracket to demonstrate the importance of the device.Accuracy and reliability of the simulated results were verified against experimental data.【Result】When water flow rate is slow,pump without the bracket could result in backflow at the outlet of the inlet passage,forming a large backflow vortex.This could block the inlet passage,cause a large low-frequency pressure pulsation and energy loss,leading to a sudden pressure drop in the saddle zone as a result.The bracket can effectively restrain the scope and strength of the vortex,reducing the low frequency pressure pulsation and improving stability of the pump.It also increases the lift at the lowest point in the saddle zone by 5.5%,and reduces the shadow of the saddle.In the meantime,the bracket increases working capacity of the blade,partly offsets the hydraulic loss,reduces the head drop by 1.3%,and improve the uniformity of internal flow.【Conclusion】Adding a guide cone bracket at the inlet of vertical axial flow pump can improve the performance of its saddle zone and has potential applications.