低扬程泵装置优化水力设计的关键问题

对低扬程泵装置的优化水力设计问题进行了较为深入的研究.将低扬程泵装置效率分解为水泵效率和流道效率两个方面,讨论了泵装置中泵段的概念和泵段效率的修正等问题,分析了流道水力损失对流道效率及泵装置效率的影响,通过实例说明了流道内的流速和流态对流道水力损失的影响,得到以下结论:在低扬程条件下,尽可能减小流道水力损失是提高泵装置效率的关键;减小流道水力损失的关键是降低流道内的流速和改善流道内的流态,其途径主要包括选择水力性能最优的泵装置型式和流道型式、适当降低水泵的nD值、选择更优秀的水泵水力模型、适当放宽流道控制尺寸、对流道型线进行充分的优化水力设计等.

A study of the key problem of optimum hydraulic design for a pump system with low head

An in-depth study on the problem of optimum hydraulic design for a pump system with low head has been made in this paper.The efficiency of a pump system with low head is divided into two aspects: one is pump efficiency and the other is conduit efficiency.Some problems about the definition of pump segment in the pump system,efficiency modification for the pump segment and flow pattern of inlet conduit in the pump system are discussed.The influence of conduit hydraulic loss on the conduit efficiency and pump system efficiency is analyzed and the influence of both flow velocity and flow pattern on the conduit hydraulic loss is illustrated by calculation samples,from which the conclusions are drawn as follows: under the condition of low head,the key problem of how to increase the pump system efficiency is to reduce the conduit hydraulic loss as much as possible;The essential way to reduce the conduit hydraulic loss may be to lower the flow velocity and improve the flow pattern in the conduit.The approaches to reduce the conduit hydraulic loss mainly include: to choose the type of pump system and conduit with the optimal hydraulic performance,to suitably lower pump nD value,to choose better pump model,to suitably relax the restrictions for conduit control size,and to sufficiently optimize hydraulic design for conduit shape.