Flow-Induced Vibration of Long-Span Gates : Verification of Added Mass and Fluid Damping

Abstract

Long-span gates vibrating in the streamwise direction push and draw water in the reservoir; thus the gate is accompanied by the added mass of water. Moreover, waves propagating in the upstream direction are formed on the free reservoir surface, resulting in a fluid damping effect on the vibrating gates. The added mass and the fluid damping coefficient were derived theoretically in a dimensionless form in a previous study. To verify the theoretical results of the added mass and the fluid damping coefficient, the experimental results of a model test are presented in this study. A planar vertical gate undergoes free damped vibrations in air and still water. The added mass and the fluid damping coefficient are calculated from the measured frequencies and damping ratios of the damped vibrations. Consequently, it is shown that there is good agreement between the theoretical and experimental results.