Study On Hydraulic Design Of Inlet And Out Conduits In Large-Scale Shaft Tubular Pumping Station With Ultra-low Head ——Taking Shenjiang Pump Station As An Example

Large-scale low(ultra low)head pumping stations are widely used in water resources allocation,water environment improvement,urban flood control and agricultural irrigation and drainage projects in plain areas.It provides support and guarantee for the economic,social and ecological development of plain areas.Pump device is the core equipment of pump station,and its hydraulic performance has a great impact on the efficiency of pump station.The pump device with suitable hydraulic model and reasonable hydraulic design of inlet and outlet conduits is the basis and prerequisite for maintaining the stable,safe and economic operation of the pump station.Taking Shenjiang Pump Station as an example,this paper research the hydraulic model optimization of large-scale low head pump station and the hydraulic design of inlet and outlet conduits.Finally,the selected hydraulic model and inlet and outlet channel are researched by model test.The research contents and results of this paper are as follows:(1)For ultra-low head pump stations,Especially Shenjiang pump station,the applicable hydraulic models mainly include TJ04-ZL-07 hydraulic model and TJ04-ZL-23 hydraulic model.Through the comparison of the two hydraulic models by the selection coefficient method,it is found that TJ04-ZL-07 hydraulic model has higher device efficiency and excellent cavitation performance under the design head condition.Therefore,TJ04-ZL-07 hydraulic model is selected as the optimal hydraulic model of Shenjiang Pump Station.(2)Based on the length and line shape of shaft contraction section,the hydraulic design of shaft inlet conduit is carried out.After forming the design scheme,the whole conduit is modeled and numerically simulated in order to optimize the shaft inlet conduit with excellent hydraulic performance.Through comparative analysis of various design schemes,it is found that when the linear shape of the shaft contraction section is linear and the length is 3 times the impeller diameter,the shaft inlet conduit has better internal flow pattern and excellent hydraulic performance.It is determined that the scheme is the optimal scheme of shaft inlet conduit.(3)The setting of division pier in the outlet conduit will have a certain impact on the hydraulic performance of the outlet conduit.Therefore,from the two aspects of the length of the division pier head and the thickness of the division pier body,the hydraulic optimization design of the division pier type of the outlet conduit is carried out.The results show that when the thickness of spacer pier body is 1.4L and the length of spacer pier head is 2.12D,the hydraulic loss of the outlet conduit is small,the device efficiency is large,and the kinetic energy recovery coefficient of the conduit is relatively large.The device head is closer to the design head of Shenjiang Pump Station.Therefore,this scheme is the preferred outlet conduit division pier type.(4)The physical model test of shaft tubular pump device in Shenjiang Pump Station is carried out.The results show that the pump device has excellent energy characteristics and cavitation performance,good runaway characteristics,small pressure fluctuation amplitude and little change,and will not cause harm.It can realize the long-term safe,stable and efficient operation of the pump station.The selected TJ04-ZL-07 hydraulic model has a high degree of fit with Shenjiang Pump Station,and the hydraulic design of inlet and outlet conduits is reasonable.The research results of this paper provide a theoretical basis for the design and selection of ultra-low head pump station,and have important reference significance and engineering application value for improving the hydraulic design level of shaft inlet conduit and division pier in outlet conduit.