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The hydraulic test model was built to investigate the fluid-induced vibration of plane gate by changing the gate opening and flow rate respectively. The flow field near the gate was measured with the PIV system while the gate structure was measured with 8 channels high speed vibration acquisition system.In the experiments, the dynamic distribution characteristics of the flow field around gate and dynamics parameters of the gate structure were measured. The results show that the gate opening and flow rate affect the flow-induced vibration of gate directly. Gate vibration shows asymmetric and aperiodic coupling vibration characteristics. When the flow field interacts with gate, the flow field near the gate is further disturbed. The changes of the corresponding flow boundary conditions result in the downstream fluid showing complex turbulent motion. The hydraulic gate vibration often occurs in its opening and closing process or partial open. The reasons of gate vibration lie in two aspects. One is the effect of fluid force. Secondly, the structural rigidity of the gate is not enough (1).With the FEM and computer technology advances, numerical simulations can calculate the natural frequency of gate structure more accurately and predict the gate vibration characteristics. Literature (2-6) used numerical analysis method to analyze the impact of gate opening and hydraulic head on natural frequencies and vibration modes by establishing finite element model. Jiao (7) who adopted test and finite element method to analyze the natural frequencies and mode shapes of the gate in different conditions discussed the effects of the added mass on the vibration characteristics. Thang (8) thought that gate vibration was caused by the downstream vortex action. Jongeling (9) put forward different interpretations that downstream secondary vortex didn't transport energy to gate and structure vibration was caused by the change of pressure formed by the unstable free shear layer of bottom edge. Dong's study (10) showed that gate vibration was mainly caused by the large-scale surface vortex impinging gate repeatedly. Hardwick (11) thought that shear layer destruction and unstable reattachment action of bottom edge produced the self-excited vibration under certain conditions. Due to the complexity of flow-induced vibration and the limitations of the numerical analysis model, it is necessary to apply experiment method to reveal the internal mechanism of flow-induced vibration of the gate. The Particle Image Velocimetry (PIV) breaks through the limitation of a single-point test technology and can be used to measure the transient details of unsteady flow by comparing and analyzing the continuous multiple instantaneous velocities. PIV technology was widely used in experimental research in a variety of complex flow field (12~14). However, the PIV is mainly restricted to a single fluid field testing which is difficult to grasp the mechanical behavior of fluid-structure coupling system. In this paper, the synchronous measurements both flow field and gate vibrating parameters are conducted by using the PIV system and DEWE-43A vibrating data acquisition system. The results can provide a hydrodynamic basis for hydraulic gate vibration problems and a reference for design and operation of gate.

Fluid-induced Vibrations Test of Hydraulic Plane Gate for Different Conditions