Cross influence of discharge and circulation on head loss of conduit of pump system with low head
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摘要: 流道水头损失与流量及环量之间的关系,是低扬程泵装置水力设计理论中对提高其水力性能的研究具有较大影响的重要问题.低扬程泵装置水泵导叶出口水流所具有的速度环量使上述关系变得复杂起来,需全面认识.研究结果表明:在无环量的条件下,进、出水流道水头损失与流量平方成正比;在Reynolds数达到阻力平方区要求的条件下,在一定转速范围内,对于不同转速下运行时的相似工况,流道水头损失与流量平方成正比,表现为泵装置效率保持不变;低扬程泵装置中设计流量时的出水流道水头损失决定于导叶出口水流的速度环量,两者之间的关系为一开口向上的曲线,存在最优环量;在低扬程泵装置变工况运行的条件下,出水流道水头损失受流量和环量的交叉影响,在水泵正常运行工况范围内,流道水头损失与流量之间呈现出接近于线性的关系,其机理有待进一步深入研究.Abstract: The relationship between the head loss and the discharge and circulation of the conduit of a pump system with low head is an important problem with an obvious influence on the improvement of its hydraulic performance. The velocity circulation from the pump guide vane makes the relationship more complicated, which has to be understood comprehensively. The results indicate that, under the condition of zero circulation, the head loss of the inlet and outlet conduits is in proportion to the square of discharge. Under the condition that the Reynolds number is satisfied with the resistant square area, the conduit loss is in proportion to the square of discharge for the similar working points with different speeds in a certain rotational speed range, indicating that the pump system efficiency is constant. The outlet conduit loss of design discharge for a pump system with low head depends on the velocity circulation from the guide vane exit, and the relationship between the loss and the circulation is an open curve with an upward direction, meaning that there is an optimal circulation for the loss. Under the condition of various working points for a pump system with low head, the head loss of the outlet conduit is under the cross influence of both the discharge and the circulation. As a result, the relationship between the head loss and the discharge is almost linear, and the mechanism needs to be further studied.
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Key words:
- discharge /
- circulation /
- low head /
- pump system /
- conduit /
- head loss
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