轴流泵出水管内部流动水力特性研究

Study on Flow Hydraulic Characteristics in Outlet Pipe of Axial-flow Pump

用五孔探针测定轴流泵出水管内部三维流场,揭示其流动规律,分析流场形成机理,利用流场数值模拟方法计算出水管水力损失.结果表明,后导叶出流环量较大,由于出流环量和出水弯管二次流的共同作用,出水管内为复杂的螺旋流,断面轴向流速和周向流速分布不均匀、不对称,与常规轴向均匀流和对称流的假定不符.过大的环量增大了出水管内水力损失,减小环量可减小水力损失,提高泵装置效率4%～8%.

The 3-D flow fields in outlet pipe of an axial-flow pump were measured with 5-hole probe. The flow regularity was disclosed and the formation mechanism was analyzed. Hydraulic losses of outlet pipe were calculated through flow fields＇ numerical simulation. The results indicated that there was big circulation in outlet of exit guide vane. Under the co-action of circulation and secondary flows of outlet curved pipe, the flow in outlet pipe was complex spiral flow and axial and circumferential velocities of flow on cross sections were neither even nor symmetrical, which was different from normal assumption of even or symmetrical flow. The excessive circulation increased outlet pipe hydraulic losses. The hydraulic losses could decrease and pump assembly efficiency could increase by 4%～8% through decreasing the circulation, which meant much to optimum design of an axial-flow pump assembly.