Research And Application Of The Pump System Energy Performance Calculation Method For Large Scale Low Head Pumping Stations

Large scale low head pumping station play an important role in water resources dispense,agricultural irrigation and drainage,water environment improvement,urban flood control and drainage,etc.There are a large number of large scale low head pumping stations and huge total energy consumption in China.In order to adapt to the development trend of energy saving and emission reduction,the requirement of energy performance of pumping station is more and more high,especially for large scale low head pumping station with long running time,so the energy performance index of pump system has been paid more and more attention in recent years.For a long time,the energy performance of the pump system has been obtained by means of theoretical analysis or model test.By using the method of pure theoretical analysis,the derivation process often necessary to make use of some approximation or assumption,which is quite different from the actual situation.The accurate energy performance index can be obtained by means of the pump model test,however,this method has the disadvantages of long cycle and high cost,and not conducive to the comparison of several schemes.In order to understand the performance index of the pump system timely and accurately in the design process of large scale low head pumping station,and for evaluate scientifically whether the selection of pump and pump system and the hydraulic design of the inlet and outlet conduits are meet the requirements.So it is necessary to study a method for calculating the energy performance of the pump system with high accuracy and convenient application.The calculation method is combined with numerical simulation and model test,based on the model test,supplemented by using numerical simulation,then the calculation method can be compiled into a computer software which is easy to apply.The contents included are as follows:(1)Based on the research of relevant data,this paper analyzes the influence of the pump head,the hydraulic performance of the pump and the nD value,the conduit type and the hydraulic performance of the inlet and outlet conduit on energy performance of low head pump system.(2)Based on the research of the optimum hydraulic design in the inlet and outlet conduit of low head pump system,such as the vertical axial-flow pump system,the inclined axial-flow pump system and front-positioned pit tubular pump system.The flow pattern and the head loss of inlet and outlet conduits are obtained accurately by the CFD numerical simulation,then the flow pattern is examined by model tests of transparent conduit.(3)The difference performance between the pump segment and pump model test section are analyzed in detail.The correction of the pump segment efficiency according to the result of model pump test on the same test stand as the SNWD model pumps.(4)The calculation method of the pump system efficiency according to the calculation results of the conduit and the pump segment and the energy balance between the pump and the pump segment.The calculation results of the pump shaft power,the pump head and the pump system efficiency are compared with the test results of the pump system model to verify the accuracy of the calculation results.(5)The Visual Basic 6.0 is used as the software platform,and the calculation method of the energy performance of the large low lift pump system is programmed into the computer software.After comparing the calculation results of several engineering examples with the pump model test results,the calculation accuracy can meet the requirements of the application of large pumping station.This calculation method can be used in pumping station engineering design project proposal,feasibility study and preliminary design stages,and provide scientific basis for pump system selection,design and tender.It is of great theoretical significance and practical value to improve the design quality and construction level of pumping station.