A Research On Hydraulic Analysis Of Internal Flow Field And Application Of FLUENT Simulation In Rainwater Pumping Station

The newly revised Outdoors Drainage Criterion by the Ministry of Housing and Urban-Rural Development was issued and came into force in April,2014,which pertaining to the calculation of rainwater quantity improved the recurrence interval P and modified the coefficient m(m=1)in calculation formula of rainwater quantity.For engineering design,the visual changes are the increase of rain pipe diameter level and water treatment capacity in local rainwater pumping stations,so,there will be more large rainwater pumping stations accordingly.To make sure the design of rainwater pumping stations tally and accord with later operation,more and more rainwater pumping stations construction projects simulate flow condition by using computer technology at the design stage.Therefore,by example of the project of rainwater pump station(Q=17m3/s)of Taohua Temple,this paper will conduct a study on inner flow field of pump stations from two aspects – hydraulic analysis and flow regime simulation by FLUENT software,and give guidance on the process design of the size of the structures in this project.The specific research contents are as follows:(1)Hydraulic analysis of flow field.Hydraulic analysis is the theoretical basis of designing pumping stations.This paper will analyze the flow regime of forbay,collecting basin and discharge bay in rainwater pumping stations and make the flow field go steadily through flow velocity,angle and process size;(2)FLUENT computational simulation.FLUENT computation consists of the entrance velocity of inlet conduit,boundary conditions of free flow,entrance velocity of outlet conduit,boundary conditions of pressure outlet,and rigid boundary condition of inlet and outlet conduit.All these are used to confirm the rationality of the pumping station in a more visualized way.After hydraulic analysis and FLUENT computation,the equipments and the design size of the main structures for the rainwater pump station of Taohua Temple are determined as follows:(1)Inflow valve pit: reserve four square openings of 2200mm×2200mm,and equip four set of 2200mm×2200mm square valve gate of cast iron inlaid with cooper and with rising stem,and the flow speed through the valve gate is 0.88m/s.(2)Grid well: select 4 unit of rotation raking grille remover with flow ofQ=4.25m3/s,grid width B=2800mm,installation angel 70°,net distance between grid bars 40 mm,and the flow speed through the grid bars is 0.88m/s.(3)Collecting tank: according to the project,select the pumps in principles of combining short-term and long-term project and matching large and small pumps and use 8 sets of diving axis flow pump: 6 large pump each with flow speed of Q=2.4m3/s;two small pumps each with flow speed of Q=1.2m3/s,and the front flow speed of bellmouthing of the water pump is 0.67m/s.(4)output sump: output water type is prefixal pressure output in forward direction of the sump,and then while the pressure is released by the upper tank,the output water is led to the North Canal in way of gravity flow by double row quadrate culvert of 3000mm×3500mm,with the flow around the outlet at a speed of 0.80m/s.