Numerical Simulation And Analysis Of Complex Flows In The Integrated Prefabricated Pumping Station

As a new type of pumping station,the integrated prefabricated pumping station has been used extensively in municipal engineering projects.The important function of the integrated prefabricated pumping station,as well as its advantages of small size,low cost of manufacturing and installing,and convenient maintenance,has been acknowledged.Considering the reported works on the integrated prefabricated pumping station,engineering applications were emphasized,while the understanding of the internal flow mechanism remains insufficient.For this reason,the present study was carried out on the flows in the integrated prefabricated pumping station.Various applications necessitate the consideration of the integrated prefabricated pumping station from both low and high flow rate operation conditions.Here,the hydraulic design of two integrated pump stations was separately performed.The single-tank structure was adopted for low flow rate condition,while multiple tanks were for high flow rate condition.For the latter,a novel scheme was proposed with the tanks being arranged in parallel;moreover,sequential and symmetric configurations were attempted respectively.Based on the devised pumping station models,computational domains were constructed,grids were used to discretize the domains,and governing equations were associated with the grid nodes.Numerical simulation of the flows in the pump station was conducted,then,the results were analyzed.The major conclusions obtained in the present work are following:(1)For the prefabricated pumping station operating at low flow rate,as two or three pumps operate simultaneously,the flow rate of each pump is nearly equivalent,indicating no interference arising between the pumps.The distribution of static pressure in the pump flow passage slightly varies with the change in the number of simultaneously operating pumps.In contrast,the difference in the distribution of static pressure or velocity at the pump inlet is obvious as the operation scheme shifts from single-pump operation to two-or three-pump operation.More specifically,as the three pumps operate concurrently,distributions of flow parameters are remarkably non-uniform in the tank and three-dimensional flow structures are excited as a consequence.(2)Regarding the sequentially parallel and symmetrically parallel schemes,all the tanks are associated with the same tendency of flow rate allocation,which indicates that the flow rate occupied by the tank increases with the distance between the tank and the inlet pipe of the pump station.In comparison,for the sequentially parallel scheme,the gap of the flow rate or the pump efficiency between the two pumps located in the same tank is more obvious.Meanwhile,the interference between the two pumps in the same tank is relatively alleviated for the symmetrically parallel scheme;therefore,the operation states of the two pumps are consistent.(3)Local velocity at the inlet of the tank is fairly high,as is common for the two parallel schemes;the inflow velocity associated with the sequentially parallel scheme is even higher.For both the two parallel schemes,strong and weak parts are manifested in the flows at the bottom of the tank;moreover,uneven bottom flows is prominent for the symmetrically parallel scheme.Because the velocity magnitudes in the core area of the bottom flows are larger than 0.3 m/s,as is shared by the two parallel schemes,deposition is not anticipated to occur in all the tanks.