| The new type tubular pumping system—shaft intake and siphon discharge pump device combine the advantages of shaft inlet flow conduit and siphon outlet conduit,making this type of water pump device widely used in practical engineering construction in recent years.The pump device has good ventilation conditions,good heat dissipation,convenient and simple flow-breaking mode,and there is no need to install two gates at the outlet flow path,which is very convenient in the later period of maintenance and saves a lot of costs.The continuity equation and Navier-Stokes equation are selected as the control equations,the standard k-ε turbulence model and the SIMPLEC flow field numerical calculation method to scientifically and accurately describe the inner flow field of the pump device.TurboGrid is used to build three-dimensional models of impeller and guide vane,and the channels are meshed.Three-dimensional models of various inlet and outlet conduits are created using UG software and meshed using ICEM CFD.Finally ANSYS CFX software is used to simulate the inner flow of the pump device.The main research contents of this paper through numerical simulation with CFD are three aspects:(1)Study the external characteristics and internal flow of the shaft intake and the siphon discharge pump device under different flow conditions;(2)Study the shaft in-flow,siphon out-flow pump device with the same form,the siphon outlet conduit hump position on the performance of the entire pump device;(3)Analyze the performance of three different types of tubular pump devices,the shaft inflow-siphon out flow,the shaft inflow-straight pipe outflow and the straight pipe inflow-siphon outflow.The main conclusions are as follows:(1)The hump has no influence on the head of the pump device under different flow conditions under the three different horizontal positions selected in this paper.The efficiency of the different designs does not exceed 1%,and the siphon conduit hydraulic loss is influenced greatly.In this paper,the horizontal direction of the hump is closer to the outlet,the smaller the hydraulic loss,the overall hydraulic loss of the siphon conduit in three schemes does not exceed 0.3m under design flow conditions;(2)Different hump heights have little effect on the head of the shaft inflow-siphon outflow pump device under different flow conditions.The greater the distance from the hump to the center line of the impeller,the corresponding head of the tubular pump device is slightly increased.Different hump heights have great influences on the efficiency of shaft inflow-siphon outflow pump device under different flow conditions.The greater the distance between the hump and the center line of the impeller is,the higher the efficiency of the pump device.The maximum efficiency difference between different schemes under design flow conditions is about 3%;(3)Doing contrast analysis performance and internal flow of the three different types,They have their own characteristics,in terms of efficiency,the efficiency of shaft inflow-straight pipe outflow is slightly higher than that of the other two types of pump devices,but considering the fact that straight pipe outflow channels in practical project needs two gates and the costs of post-maintenance,this kind of pump device can be firstly chosen under the allowed conditions,because of its convenience of breaking method and less cost of post-maintenance.For the straight pipe inflow-siphon outflow pump device,although using a straight pipe provides a very good intake condition for impeller,because of the need to place the motor below the siphon conduit to increase the amount of construction and construction difficulty,and the motor is placed under the siphon conduit,its ventilation moisture-proof conditions are not as good as if they were placed directly in the shaft.Therefore,careful consideration should be given to the selection of pump device structure.Through the research of this article,it can provide reference and guidance for designing the siphon conduit and the selection of the type of the tubular pump device.It is very significant for the follow-up research work and making a choice in practical engineering. |
