基于全流道模拟的泵装置出水流道水力特性分析

Analysis of Hydraulic Performance of Outlet Passage Based on Simulation of Steady Flow in Whole Passage of Axial-flow Pumping System

为研究低扬程泵装置出水流道的水力性能，采用CFD方法对泵装置进行全流道数值计算，并通过模型试验对数值计算结果的准确性进行验证。分析了隔墩对出水流道水力性能和泵装置能量特性的影响，阐述了出水流道流量不平衡的问题以及环量对出水流道内部流动特性的影响。结果表明：对于低扬程泵装置，出水流道的隔墩对泵装置能量性能的影响较大，应尽量避免设置隔墩；在出水流道中，隔墩前伸会增加出水流道的水力损失，导致两孔流量分配更加不相等，隔墩后伸对两孔流量的分配无影响但会增加出水流道的水力损失，从而降低泵装置的水力性能。无环量时出水流道的水力损失与流量呈二次方关系，有环量时出水流道的水力损失增大，且内部流态变得复杂。出水流道的内外特性与泵装置的运行工况有关系，应避免将出水流道独立地从泵装置系统中脱离出来进行水力性能的计算分析。

In order to investigate the influence of dividing pier on the hydraulic performance of a low-lift axial-flow pumping system, CFD method was used to simulate the three-dimensional internal flow of a low- lift pumping system with different outlet passages. The performance of the pumping system was estimated, and was compared with test data. Focusing on analyzing of the influence of dividing pier on the hydraulic performance of outlet passages and external characteristic of the pumping system, flows in two channels of the outlet passage are unequal to each other, the flow imbalance problem and the influence of velocity circulation on the hydraulic performance were analyzed as well. Results show that the dividing pier has great influence on the performance of the low-lift pumping system and should be avoided. Protrusive dividing pier makes the hydraulic loss of outlet passages increased and flow distribution more unequal. Backward extension of dividing pier does not influence the flow distribution, but makes hydraulic loss of outlet passage increase which induces degradation of the performance of the pumping system. Under the condition of zero velocity circulation, the hydraulic loss of outlet passage is in proportion to the square of flow, and the hydraulic loss is larger than that with velocity circulation and the flow is more complex. The internal and external performance of outlet passages has the relationship with the running condition of the pumping system,so it should avoid calculating the flow patterns of a separated outlet passage.