Study On Hydraulic Characteristics Of Two Effluent Structures Of Bailonggang Pumping Station

The functions of the pumping station effluent building are to improve the flow pattern,eliminate the excess energy,optimize the flow velocity distribution,and reduce the scour and siltation of the downstream water conveyance channel or the discharge area.The hydraulic loss of the pumping station effluent buildings will also affect the overall operation efficiency of the pumping station.Therefore,the reasonable design of pumping station effluent structure plays an important role in making the outflow field smooth,reducing downstream erosion and deposition,improving the overall efficiency of pumping station and improving flood control safety.Bailonggang Pumping Station is located in Leliuhong Plain in Yueqing City,which is one of the most important drainage projects in Zhejiang Province.The main purpose of the construction of Bailonggang Pumping Station is to meet the needs of Yueqing City to eliminate waterlogging and reduce flood disaster losses.Since the outlet side of the pumping station is the sea,and one side of the pumping station is industrial bases,the other one is the Bailonggang Gate,the available land for the project is tight.The Bailonggang Pumping Station has proposed two design schemes for the outlet building,which are open outlet sump and pressure box culvert.Therefore,it is necessary to compare and select a better one between the two design schemes of Bailonggang Pumping Station by comparing the flow hydraulic characteristics of the pressure box culvert and the open outlet sumpTaking Bailonggang Pumping Station as a prototype,this paper designs two sets of test models which are pressure box culvert and open outlet sump to compare and analyze the velocity distribution of downstream surface flow field and outlet sections of outlet structures under conventional operating conditions.The results of physical model test show that,under various conditions,the flow pattern of the open outlet sump is better,and the downstream recirculation zone is also smaller than the pressure tank culvert.Then the numerical simulation is carried out by CFX software to expand the conclusion of the physical model From the perspectives of constant flow?variable water level and constant water level?variable flow,the influence of different effluent structure forms on outflow under various working conditions is comprehensively compared and studied.Numerical simulation results show that,no matter under what working conditions,compared to pressure box culvert,the downstream reflux range of the open outlet sump is smaller,the range of the high speed zone is more concentrated,the velocity distribution of the downstream corresponding outlet flow section is more uniform,and the hydraulic loss is smaller.Finally,comparing the results of the physical model test under the design water level and the design flow with the numerical model calculation results,it is found that the numerical model and the physical model results are basically the same,indicating that the research based on the numerical simulation is consistent with the actual situation,and the numerical simulation has high credibility.Based on the results of physical model test and numerical simulation,from the perspective of the influence of downstream outflow flow characteristics on overcurrent,in the outlet structure of Bailonggang pumping station,the open outlet sump is better than the pressure box culvert.