Research On Static And Dynamic Characteristics Of Three-arm Radial Gates

Metal structure is indispensable for the normal operation of hydraulic complex.And as the controlling device of the discharge channel,the safety of gates is the priority for all.Among all kinds of gates,the radial gate has many advantages like light structure,reasonable stress distribution,convenient operation and good flow pattern.However,as a complicated space structure,either the arrangement mode of the arms,the opening dimension,or the water load will influence its working characteristics.So that it is essential to research on the static and dynamic characteristics of racial gates in special shape.Based on the radial gate of Haokou Hydropower Station with large dimension,low water head and three arms,the paper built a 3-D FEM model to analyze the static and dynamic characteristics of the gate with ANSYS,thus offering reasonable suggestion for the optimizing design and daily safety of the structure.The paper firstly summarized the research progress in radial gate design and vibration around the world in recent years,and introduced the characteristic and function of ANSYS,which adopted in the analyzing progress.Besides,the paper briefly explained the basic concepts and analysis procedure of FEM method,especially for the thin-plate finite element method and the mode analysis method which would be used in natural vibration analysis.Secondly,through the FEM model of Haokou radial gate with three arms,the paper made three set of comparative analysis of the static characteristics-when the gate closed or at the moment it opened,before and after the shape of Kucha Part,two different arrangement forms of the arms in radial gate.It indicates that the stress distribution of the radial gate has no change after the gate opened.However,after the gate being lifted,the chief displacement has changed to the fixed axis rotation,which was deflection towards downstream before that.And aiming at the calculation result of original shape,good improving effect was received by thicken the steel plate of transition part of the Kucha structure.Comparing to the gate shape in three arms,the two-arm shape has worse structural rigidity,which will make the gate leaf bend towards downstream.And the crossing angle will make the bearing stress appear in the joint of arm and gate leaf.Finally,based on the possible vibration damage of the original shape,a good optimized effect and structural arrangement were got by strengthening the weak part.It indicates that the natural vibration frequency of low step can be increased and its vibration mode can be changed through strengthening the weak part of the radial gate.Taking the coupling of the gate and water into consideration.the tangential movement was change in priority because that the added mass of water body was perpendicular to the face slab of the radial gate.And the natural vibration frequency was reduced as well.The contact area will decrease along with the opening degree increasing,which weaken the influence effected by the additional mass of the water body.Thus increasing the natural vibration of the radial gate.Therefore,the operation in low opening degree should be avoided as much as possible in ordinary operation of the radial gate.