Investigation On Flow-induced Vibration Control Of Radial Gates In Hydraulic Structure

Radial gates are widely used in hydraulic project. One of the key problems in designing radial gate is to solve flow-induced vibration. The cause of severe vibration is the formation of a self-excited vibrating system by the joint of the gap jet and turbulent flow downstream the gate. In the case of small opening, submerged discharge, and water-stop rubber damage, the interaction between water and gate may cause vibration which result in gate damage. In order to diminish the vibration, it is not enough to improve hydraulic condition and optimize gate structure. Employing control method is further way to solve the problem. One of the radial gates is used in this paper to study the application of passive and intelligent semi-active MR dampers in flow-induced vibration control of radial gate.Realization of vibration control of the harmful flow-inducing vibration of radial gate needs simplified model and random fluctuant pressure simulation. In the paper, a simplified 3 dimensional model is created on the basis of finite element analysis, which the beams of the gate must be kept, the plate can be ignored, but the mass of plate is distributed to relevant beams. Three dimensional finite element method is used to calculate the structural dynamic properties, and the principle of equivalent dynamic properties is adopted to modify the simplified mechanical model of radial gate and to determine 3 dimensional simplified structure model and its system parameter of the equivalent radial gate. The results of analysis and calculation show that the simplified 3 dimensional mechanical model can reflect the dynamic properties of radial gate structures and the vibration reaction of stochastic pulse pressure. Therefore, it can be used in the intelligent control design of radial gate installed with dampers. In regard to fluctuant pressure simulation, linear filter method is applied. The simulation load is produced from a stochastic white noise and used as load input of dynamic analysis of flow-induced vibration of radial gate.The properties of the MR smart materials and the MR smart dampers are all introduced in the paper. Then, some kinds of main mechanical models of MR damper are presented particularly and the analysis and comparison of their characteristic are executed. Simultaneously, the revised Bingham model of MR damper is introduced in line with the experiment results.The flow-induced vibration control of radial gate using passive and intelligent semi-active MR dampers is studied mainly in this paper. With regard to semi-active control algorithms, a LQR semi-active method, which is based upon classical LQR theory, is put forward in seismic vibration control of radial gate. A fuzzy semi-active control algorithms, which uses the feedback of damper motion status, is also presented in flow-induced vibration control of radial gate. The two methods are used respectively and detailed parameter studies are taken in the former method. Then, the analysis and comparison of their results and feasibility are executed. The results indicate that intelligent dampers using the two algorithms can effectively reduce the flow-induced vibration responses. The parameter analysis shows that the factors of semi-active control algorithms have great influence on control effect. Obviously, the reasonable parameters are necessary for excellent control effects.