Study On Standardization For The Elbow Inlet Conduit In Large And Medium Pumping Station

Large and medium pumping stations play very important roles in reasonable allocation of water resources, urban flood control and drainage, agricultural irrigation and drainage and other fields. China’s central and local governments are constantly increasing investment in water conservancy construction, and it can predict that the construction of large and medium pumping stations will also usher in a period of peak. Due to the advantages of mature technology, managing and maintaining easily, high operational stability and reliability, vertical pump system has been widely used in large and medium pumping stations. Inlet conduit is the transition between forebay and pump impeller chamber in the vertical pump system. Its role is to guide the process of the water flowing from the forebay into the pump impeller chamber orderly steering and uniform shrinking, in order to meet the requirements of the pump impeller chamber inlet flow pattern. Standardization design for the inlet conduit has very important significance for ensuring stable and efficient operation of large and medium pumping stations.Elbow inlet conduit is the most widely used in supporting the use of vertical pump system.14newly created vertical pumping stations of East-Route South-to-North Water Transfer Project all use elbow inlet conduit. Facing the requirements of actual project for the elbow inlet conduit, there are two increasing sticking problems of the design for the elbow inlet conduit: there is not reliable guarantee of the design quality of the elbow inlet conduit, due to the differences of the designers’ experiences; there are a great deal of repeated designs and researches in the process of design.Major significances of the standardization design for elbow inlet conduit:could ensure the high quality of its hydraulic design, in order to ensure the reliability and economy of the pump running; could avoid a large number of repetitive researches of optimum hydraulic design and model test for the inlet conduit.The statistical results for the controlled size ranges of the elbow inlet conduit in vertical pump system show that the relative values of the controlled sizes vary little, and the discreteness to the average is small, so it could be standardized conveniently. Draft tube in hydropower has been early implement of standardized design, and it played an important role in improving the design level of the hydropower station.Consequently, on the basis of a great deal of the theoretical researches and engineering applications for elbow inlet conduit, this paper carries out researches for optimum hydraulic design for elbow inlet conduit,and proposes standardization issue for elbow inlet conduit,and conducts research for the correlative matters of its standardization. The contents included are as follows:(1) Based on the analysis of the theory of hydraulic design methods of inlet conduit in large-scale pump system, ranges of controlled sizes relative values of elbow inlet conduit in the actual engineerings had been analyzed.(2) The importance and forms of standardization were showed, and the requirements of standardization for the elbow inlet conduit and the research methods were proposed.(3) Mathematical model of parametric design for elbow inlet conduit were proposed, and the mathematical model of three-dimensional turbulent flow numerical computation were expressed.(4) Treating the uniformity of velocity distribution and the flow average angle entering the pump at the outlet section of inlet conduit as objective function, the optimum hydraulic design for the primary geometric parameters of the elbow inlet conduit in common range were carried out.(5) This paper researched the series division of the proposed standardization elbow inlet conduits, and computed the hydraulic performances of the proposed standardization elbow inlet conduits by three-dimensional numerical computation.(6) Comparative analysis for the results of numerical computation and model test for elbow inlet conduit were carried out to check out the research method, which this paper adopted, feasible and reliable.The conclusions are as follows:(1) The standardization design for the elbow inlet conduit in vertical pump system of large and medium pumping stations has important theoretical value and practical significance;(2) Based on the analysis of the range of controlled sizes of the elbow inlet conduit in actual pumping stations and the research on the optimum hydraulic design, this paper obtained reasonable series division of the proposed standardization elbow inlet conduit.(3) Optimum hydraulic design for proposed standardization elbow inlet conduits has been conducted. And their hydraulic parameters are excellent, so the proposed standardization elbow inlet conduits could provide ideal flow conditions for large and medium pump system.