竖井对低扬程贯流泵装置性能影响的数值模拟

Numerical simulation of influence of shaft on performance of low head tubular pumping system

为研究竖井贯流泵中竖井部分对贯流泵装置的水力性能的影响,采用计算流体动力学方法对包含进出水延长段、进出水流道、叶轮和导叶在内的整体泵装置进行数值模拟,分析竖井长度、竖井头部型线以及竖井尾部型线对进水流道水力损失、出口断面轴向速度分布均匀度、出口断面速度加权平均角以及泵装置能量特性的影响.结果表明:竖井长度、竖井头部和尾部型线对进水流道水力损失和出口断面速度加权平均角有影响,但是对进水流道出口断面轴向速度分布均匀度几乎没有影响;竖井尾部型线对流道水力损失影响最为显著,在设计流量工况下,竖井头部和尾部皆为锥形型式的进水流道水力损失较头部和尾部皆为圆弧形型式的进水流道的水力损失小24%;竖井头部型线和尾部型线采用锥形型式的进水流道水力性能更优,但是在选择锥形型线时应注意不要延长竖井尾部长度.采用模型试验对数值模拟结果进行了验证,两者结果吻合较好,表明该数值模拟方法是可靠的.

In order to study the influence of shaft on the hydraulic performance of low head tubular pump,CFD method was used to simulate the whole pumping system including inlet and outlet water extension,inlet and outlet passage,impeller and guide vane.The influence of shaft length,shaft head profile and shaft tail profile on hydraulic loss of inlet passage,uniformity of axial velocity distribution at outlet section,weighted average angle of velocity at outlet section and energy characteristics of pumping system was analyzed.The results show that the hydraulic loss of the inlet passage and the weighted average velocity angle at the outlet section are affected by the shaft length,shaft head profile and shaft tail profile,but the uniformity of the axial velocity distribution at the outlet section of the inlet channel is almost not affected.Under the designed flow rate condition,the hydraulic loss of the inlet passage with cone-shaped head and tail is 24%less than that of the inlet passage with arc-shaped head and tail.Therefore,the hydraulic performance of the inlet passage with cone-shaped head profile and tail profile is better,but when selecting the cone-shaped line,attention should be paid not to extend the tail length of the shaft.The results of numerical simulation are verified by model test.The two results are in good agreement,and the numerical simulation results are reliable.