Abstract
A two-dimensional unsteady fluid–structure interaction numerical model was established, based on the physical model test, to investigate the influence of vertical vibration on the holding force of an emergency gate in the closing process. Gate motion was controlled by the user-defined function in Fluent. Attention was paid to the relationship between the vertical vibration, hydrodynamic loads and flow discharge. The experiment results show that holding force has three typical forms in the closing process and it is related to the service gate height. The numerical model can reflect the gate vertical vibration and the gate-closing displacement in the form of steps. Gate vertical vibration in the closing process is a motion-induced vibration caused by gate active falling. Moreover, the transition from full-flow to open-flow behind the emergency gate has a great influence on the gate vertical vibration. With a small gate opening, gate vertical vibration makes the flow discharge fluctuation increase. Furthermore, flow discharge has an influence on the gate body loads, which is mainly concentrated in the upstream plate and gate bottom. Finally, the lift force coefficient at the gate bottom is different from the standard and is mainly controlled by the outflow boundary condition. The simulation result is in good agreement with the experiment and the relative error meets engineering requirements, suggesting that the numerical model can successfully simulate the gate fluid–structure interaction and reproduce the characteristics of physical quantities in the closing process.
Highlights
IntroductionGate vibration is a common phenomenon in water resource and hydropower projects
Accepted: 9 September 2021Gate vibration is a common phenomenon in water resource and hydropower projects.The vibration is motivated by the hydrodynamic loads, and the flow field around the gate produces changes in turn, which forms the fluid–structure interaction between the fluid and gate structure [1]
The results showed that the smaller was the gate opening height and the larger was the flow discharge, the more obvious was the gate vibration, which indicated that the discharge had a direct influence on the gate vibration
Summary
Gate vibration is a common phenomenon in water resource and hydropower projects. The vibration is motivated by the hydrodynamic loads, and the flow field around the gate produces changes in turn, which forms the fluid–structure interaction between the fluid and gate structure [1]. Strong fluid–structure interactions can cause gate structure deformation or even destruction, posing a serious threat to the safety and stability of the water conservancy project. Hardwick [3] and Jongeling [4], through a physical model test, pointed out that the main cause of gate vibration was the vortex formed by the destruction of the free shear layer at the gate bottom. Ishii and Knisely [7] reckoned that the fluid feedback force induced by gate vibration mainly included two aspects: pressure pulsation caused by flow and alternating excitation derived from the vortex at the gate bottom. Kunihiro et al [8] expounded that the curved gate vibration belonged to the self-excited vibration in the small gate opening
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