Study On The Influence Of Flow-induced Vibration On Panel Force And Opening And Closing Force Of Gate

Flow-induced vibration is a phenomenon which widely existing in the process of opening and closing of hydraulic gates.In the existing hydraulic projects,some of the gates’ opening and closing force with serious vibrations will suddenly increased,so that the gates cannot be normally opened and closed.This situation seriously threatens the normal operation of the hydropower station and the safety of the upstream and downstream.At present,through the physical model experiment and numerical simulation of the gate,the influence of the flow-induced vibration on the gate is explored.However,these studies mostly stay on the stability of the gate structure.Therefore,in order to prevent the abnormal change of the gate opening and closing force under the influence of vibration,it is necessary to further improve the formula of the opening and closing force of the gate,so that it is suitable for the calculation of the opening and closing force under the influence of vibration.By analyzing the change of gate pressure under the influence of flow vibration,and simplifying the overall model of the gate,the calculation formula of the pressure of the gate panel is derived,and combined with the formula of the opening and closing force,the problem that the gate opening and closing force is not accurate under the influence of flow-induced vibration is solved.The major research achievement is given as follows:(1)Based on a river channel gate in middle of Liaoning,the three-dimensional fluid-solid coupling numerical simulation under different opening degrees is carried out in order to obtain the force and vibration displacement of the gate panel.The results show that the overlay or offset of excitation force which caused by flow-induced vibration and the water pressure before the gate is the main cause of the change in the opening and closing force of the gate.(2)By simplifying the gate model properly and considering the overall vibration,according to the phenomenon that the gate panel pressure increases under the influence of flow-induced vibration,the calculation formula of the water pressure before the gate is improved in order to obtain the relationship between the water pressure,displacement of the gate panel and the water head before the gate.It also is verified by the three-dimensional fluid-solid coupling numerical simulation results of a river gate project in middle of Liaoning and the radial gate of the Maerdang hydropawer station and the results are in good agreement.The feasibility of the water pressure calculation formula before the gate.And confirm the feasibility of the calculation formula.(3)In order to solve the problem that it is difficult to directly measure the force of the gate panel in the actual measurement and the physical model process,the waveform synthesis method is adopted for the flat gate,and the improved point-to-face conversion method is adopted for the radial gate.And this method can convert the point pressure data which can be measured by the physical measurement and the physical model into surface pressure.It provides a practical method for calculating the force of the gate panel.(4)Based on the calculation method of gate panel pressure under flow-induced vibration,the original opening-closing force formula is improved after considering the influence of flow-induced vibration on the panel force,friction coefficient and friction arm.The results show that under the premise of stable gate structure,the calculation results of the opening and closing force are in good agreement with the actual measurement,and the relative vibration of the small opening gate is severe,the opening and closing force of the gate changes drastically,but the overall impact range is 5%-15%.