泵段、水泵模型测试段与泵段效率修正

根据低扬程大型泵站泵装置出水流道的水力设计要求,修正了＂泵段＂的定义,计算了水泵模型测试段中进出水管道的水力损失,并对＂泵段＂效率进行了修正;根据修正后的＂泵段＂效率对南水北调东线工程3个泵站设计工况的＂泵段效率＂、流道效率和泵装置效率之间的关系进行了验证性计算。研究结果表明：＂泵段＂宜定义为由水泵叶轮和导叶体这两个最基本的过流部件组成;南水北调工程水泵模型同台测试提供的水泵模型综合特性曲线表达的是水泵模型测试段的水力性能,其中包含了测试段中进水管道和出水管道的水力损失;大型泵站泵装置中的＂泵段＂性能应在水泵模型测试段水力性能的基础上考虑进出水管道水力损失进行修正;由水泵模型测试段性能修正得到的＂泵段＂扬程和效率均较水泵模型测试段高,设计流量时的扬程修正值约为0.15m左右;效率修正值与水泵模型测试段扬程有关,水泵模型测试段扬程愈低,修正值愈大,其幅度约为（1～4）%。流道效率根据流道水力损失及泵装置扬程计算得到,根据流道效率和修正后的＂泵段＂效率对设计工况的泵装置效率进行预测,其结果与泵装置模型试验得到的结果相比小于1%。

Pump segment,model pump test section and pump segment efficiency modification

Pump segment(PS) is redefined to meet the requirements on hydraulic design of flow passages of large-size low-head pump system,and PS efficiency is modified by the measured head losses in the inlet and outlet pipes of model pump.By the modified efficiency,calculation is made to verify the relationship between PS efficiency,conduit efficiency and pump system efficiency for three pump stations on the eastern route of south-to-north water diversion(SNWD).Results indicate that PS should be defined as two basic components,pump impeller and guide vane.The integrated characteristic curves provided by a model pump test on the same test stand as the SNWD model pumps,represents the hydraulic performance of model pump test section(MPTS) including the head losses in the inlet and outlet pipes of test section,and thus the PS performance of a large pump system should be modified to account for the head losses in the inlet and outlet pipes of MPTS.As both the modified values of head and efficiency of a PS are greater than those of MPTS,head modification is roughly 0.15m under the design flow rate.Efficiency modification in the range of 1-4% depends on the head of MPTS,with greater modification for lower head cases.Conduit efficiency is calculated using conduit loss and pump head.By using this efficiency and modified PS efficiency,the pump system efficiency of design condition may be estimated.The difference between such an estimation and the tested value is usually less than 1%.