Study On Comparison Of Pump Models And Hydraulic Characteristics Of Inlet And Outflow Channels In Shengqiao Pump Station

The large low head pump station is widely used in China.It is an important water conservancy project building.It plays an important role in water resources deployment,urban flood control,irrigation and drainage and improvement of water resources.The hydraulic performance of the pumping device has received increasing attention in large low lift pumping stations.Its hydraulic performance is closely related to pump selection and hydraulic design of the inflow and outflow channels.The Yinjiangjihuai project is the "South-to-North Water Diversion Project" in Anhui Province.The Shengqiao pump station is one of the cascade pumping stations of this project.The designed total flow is 150m3/s.It adopts a vertical fully-adjusted axial flow pump and the inlet flow passage adopts an elbow-shaped inlet.Water type,the outlet pipe adopts straight pipe type.Based on the basic parameters of Shengqiao pump station,the hydraulic performance of the low head pump is studied from the comparison of the pump model and the hydraulic design of the inflow and outflow channels.The pump design is used to test the results.The main research contents and achievements of this article are as follows:1)Using the same type of conversion method,based on the hydraulic performance model test results of Liushan pump station(TJ04-ZL-06)and Changgou pump station(TJ04-ZL-19)pump devices,the pumps of Shengqiao Pumping Station were selected;The model coefficient method compares the model selection of the TJ04-ZL-19 pump model and the TJ04-ZL-06 pump model at Shengqiao pump station;the results of the two selection methods show that the TJ04-ZL-19 pump model is suitable for the Shengqiao pump station.2)The basic theory of the numerical simulation of the three-dimensional flow field in the inlet and outlet flow channels of the low lift pump station is elaborated,the boundary conditions used in the flow field calculation of the inlet flow path and the outlet flow path are determined,and the inlet flow path and the outlet flow path are analyzed.The objective of hydraulic design optimization is to select the uniformity of axial flow velocity distribution,average angle of water inflow pump,hydraulic loss and resistance coefficient as evaluation indicators for hydraulic performance of inflow channels,and to select hydraulic loss and resistance coefficients as evaluation indicators for hydraulic performance of outflow channels.3)The numerical simulation results of the three-dimensional flow field in the initial scheme of the elbow inlet passage in Shengqiao pump station show that the axial flow velocity distribution uniformity and water inflow pump average angle of outlet section are 97.8%and 88.2°.Its hydraulic loss is 0.122m.The basic vertical uniform outflow;Optimized and improved influent flow channel program 2 exit section axial flow velocity uniformity and water inflow pump average angle are 98.4%and 88.3°.Its hydraulic loss is 0.108m,water flow is orderly and shrinks more evenly.4)The numerical simulation results of the 3D flow field in the initial scheme of the straight-flow outflow channel of Shengqiao pump station show that the hydraulic loss of this scheme is 0.579m,resistance coefficient is 6.43×10-4s2/m5.There is a large range of vortices on the right side of the flow channel.Through optimization and improvement,the outlet flow channel scheme 2 hydraulic loss is 0.391m,resistance coefficient is 4.34×10-4s2/m5.The hydraulic performance of the runner is significantly improved.5)We study the hydraulic performance of the model of the pump in Shengqiao pump station by means of model test of pump unit.We obtain energy performance,cavitation performance,runaway characteristics,pressure pulsation characteristics and other hydraulic characteristics in 6-blade angle model pump unit.The results show that:when the pump device is operated at a blade angle of-4° and the operating lift is 4.73m,the device efficiency can reach 75.54%,meeting the design requirements;when the design head is 4.4m,the NPSH is 8.1m;the maximum lift is 4.9m,the NPSH is 7.8m,no cavitation damage.When the-6°blade angle and head is 4.9m,the flying speed is 1.43 times the rated speed,no causing damage to the pump unit;the pressure pulsation amplitude values is +6cm and-7cm,less than 1/10 of the test head,no harm.From the point of view of numerical simulation and model test,it shows that the pump model TJ04-ZL-19 used in Shengqiao pump station has better energy and cavitation performance.Through hydraulic optimization,the overall performance of Shengqiao pump station is superior and can meet actual operational requirements.The numerical simulation results can effectively guide the model test,save costs and improve research efficiency.At the same time,the model test can verify the accuracy of the numerical simulation.The research results in this paper not only provide the theoretical basis for the design and selection of the pump unit in Shengqiao pump station,but also provide reference for improving the design quality and engineering construction level of the same pump station.