Study On Load Characteristics For Closing Process Of Unit Inlet Emergency Plate Gate In Banduo Hydropower Station

The incomplete closure of the emergency plate gate frequently occurs in its closing process for which is closed by self-weight,counterweight and water pressures in moving water,seriously threatening the normal operation of the hydropower station and the safety of residents and buildings in upstream and downstream.Therefore,a lot of researches have been carried out by researchers on the bases of hydraulic model test and numerical simulation,and the results show that the smaller gate closing force than the closing resistance in the closing process is the main reason for the gate incomplete closure.Moreover,the gate closing force is influenced by the structure of gate bottom,the angle of bottom edge,and the friction of gate supporting and water-stop.The problem of emergence gate incomplete closure is studied in this paper based on the hydraulic model test,and the stress state of the emergency gate under different gate and guide vane opening conditions are systemic analyzed.By comparing the test results of different gate structures,the reason for the aforementioned problem is clarified,and the feasible solution for promoting the gate closure is proposed.The major research achievement is given as follows:(1)In order to obtain the water pressures for the original gate structure,the water pressures of every emergency gate beam are measured.The result shows that the beam between the gate leafs on the upstream and downstream side is the bearing beam.Moreover,the larger the guide vane opened,the more water is discharged,and thus the water column pressure acted on emergency gate is larger.When the opening of guide vane is fixed,water column pressure increases with decreasing gate opening.Furthermore,the water column pressure is approximately equal to the water level difference between upstream and downstream,when the gate is almost completely closed.(2)The holding forces of the emergency gate with different bottom are compared and analyzed by modifying the gate bottom structure.It is found that the flow pattern in the sloping channel of unit inlet equipped with the emergency gate of which the bottom is leaned to downstream be fluent.Moreover,the reason for emergency gate incomplete closure in flowing water is clarified by analyzing the dynamic characteristics for the water load.(3)The available water column pressure is increased and the emergency gate can be completely closed in hydraulic model test by adding a thin leading plate on the bottom of original gate and thickening the edge of the aforementioned leading plate,,which indicates the effectiveness of the proposed solution.(4)The friction resistance can be reduced.According to the results of hydraulic model test by dividing the plane gate into two sections and closing the two gate sections one by one,the emergency gate can be completely closed and the holding force is within the hoist capacity.Therefore,this structural optimal scheme can provide reference for the solution of similar problem and the design of plane emergency gate.