Experimental Study And Numerical Simulation Of Sluices Unsteady Flow With Mutiple Outlet Sluice Opened Partly

In the background of lack of water resources,high speed development of social economy,the contradiction between supply and demand of water resource is growing in China.In the area of water shortage in the north of China,many porous floodgates and porous sluices have been built.In addition to the time of flood drainage,most of the cases are using of a few sluice gates and a complex 3D flow state behind the sluice will occur.In the process of gate opening or closing,the flow under the gate has3 D and unsteady flow characteristics,which will have adverse effects on hydraulic structures.However,the current design standard of sluice and the hydraulic design manual still suggest that the energy dissipation facilities have been calculated and designed in accordance with the formula of plane problems and steady flow conditions when design the northern sluice,which caused the severe damage of energy dissipation facilities.Based on the CFD computational fluid dynamics method,the finite difference numerical model of 3D flow under gate is established by combining the experimental research and numerical simulation.Preliminary studies have been made about the 3D unsteady flow characteristics after the sluice and the effect on the control measures.The main work and achievements are as follows:A test system of 3D unsteady flow under the opening gate of a porous sluice is designed and realized.The system is composed of a water circulation system,a gate opening and closing system and a water level automatic monitoring and acquisition system.The sampling accuracy is within ± 0.2mm,and the sampling frequency is controlled to meet the requirements of the experimentl;The gate outflow tests with different opening times and different local opening modes were carried out.According to various opening conditions,The change of water level at the downstream critical section is measured,and the flow pattern of three unsteady flow under different conditions is observed.The longer the opening duration of the gate,the longer the water level reaches stability.At the same gate opening duration,when the middle three holes were opened,the downstream water depth reached the earliest stability;Using CFD software to establish the finite difference numerical model of 3Dunsteady flow under the gate and verify the accuracy of the mathematical model simulation.The evolution process of first hydraulic jump,secondary hydraulic jump and reflux after the sluice is observed.It is found that the maximum velocity in the stilling pool during the opening of the gate is 3.6% higher than that in the steady flow field under the condition when the opening duration of the gate is 0.5min.With the same opening duration,the maximum distance between the secondary hydraulic jump and the gate is longer than that after steady flow field during the opening of the gate;Explore the effect of the guide wall on the control of the 3D steady flow and the3 D unsteady flow under the sluice.It is found that the the arrangement of 0.5 times the guide wall in the stilling pool can increase the width of the main stream,advance the position of the secondary hydraulic jump and improve the flow velocity distribution in the flow field.