低扬程立式轴流泵装置模型马鞍形区研究

Study on Performance of Saddle Zone in Low Lift Vertical Axial-Flow Pump System Model

结合南水北调东线工程某大型泵站,采用物理模型试验和数值模拟方法,对低扬程立式轴流泵装置模型的马鞍形区进行了研究。试验结果表明,低扬程立式轴流泵装置在部分流量区域出现不稳定的马鞍形区,马鞍形区扬程范围大约在1.3Hd^1.6Hd;各个叶片安放角度下的马鞍形区流量范围各不相同,在0°叶片安放角下,在50%~75%的设计流量之间出现马鞍形区。结合不同工况的数值模拟结果,对装置模型马鞍形区的流动特性进行了分析,发现叶轮进口轮缘和叶轮出口轮毂产生二次回流是造成低扬程立式轴流泵装置模型效率下降和运行不稳定的直接原因。

Combining with a pumping station in East Route of South-to-North Water Diversion Project, the method of physical model test and the method of numerical simulation were used to study the performance of saddle zone in Low Lift Vertical Axial-Flow Pump System Model. The results of the test show that： there are unstable saddle zones of the low lift vertical axial-flow pump system in the whole flow range,and the water head range of saddle zone is about 1.3Hd-1. 6Hd; the flow range of saddle zone is different in every blade angle and when blade angle is 0%, the flow range of saddle zone is about 50 %- 75 % of the design flow. The flow characteristics of saddle zone in the low lift vertical axial-flow pump system model were analyzed by combining numerical simulation results. Results showthat the second time reflex in wheel flange of runner entrance and wheel hub of runner exit is the major reason causing efficiency depression and instability in saddle zone.