The Study On The Outlet Circulation Of Mixed-flow Pump And It's Effect On The Hydraulic Performance Of The Outlet Pipe

Great progress has been made in pumping station engineering of our country since 1960'.It has played an important role in flood fighting ,water-logged area draining, draugh fighting, irrigating, water transfering and water supplying. It is the key technique to improve the efficiency of pump set performances for pump station transformation. And the loss of hydraulic of outlet is an important factors to judge the efficiency of a pump performance. The influence of outlet circulation of mixed-flow pump on the hydraulic performance of the outlet pipe was studied in this dissertation.There is circulation in the outlet of pump which makes the water flow pattern in pipeline more complicated and adds the waterpower loss in pipeline and thereby lower function of the pump performance. This essay takes the outlet pipeline of 4HBC-35 spiral mixed-flow pump as the study object, sets up test equipment and conducts the test of pump performances functions and water power loss under different operating modes; uses five-holes probe and differential pressure transmitter to test the flow velocity distribution in different modes and different sections. Datas got in flow velocity distribution test can be used as the input boundary condition in numerical simulation calculation after being simplified. The 3-dimention solid modeling will be completed by adopting the ICEM software, and the solid mode grid subdivision of much higher precision and quality will be finished by applying structured grids, unstructured grids and grid local refinement encryption technique. A numerical simulation calculation can be conducted by applying renormalization group turbulence model in CFX software and some index as flow rate, pressure and waterpower loss, etc can be got .By comparing the experimental result and the numerical one, the result that the hydraulic loss will be increased when circulation exist is obtained. By 3D numerical simulation, taking the pressure recovery coefficient in pipe as index, the rectification measures which is fit for the mixed-flow pump will be got by analysing the influence on rectification result of diversion grid in different lengths and heights.