Water Waves and Structural Loads Caused by a Periodic Change of Discharge from a Sluice-Gate

Abstract

Characteristics of water waves and structural loads induced by a forced and periodical change of discharge from a sluice-gate were theoretically analyzed, as the first approach for making clear dynamical characteristics of Tainter-gates which are being used with increased frequencies in order to control the water level of dam. It was concluded as follows: A basic parameter characterizing water waves and structural loads is the modified Froude number F0=√(d0/g)·ω(d0: the depth of the gate-opening, g: the gravitational acceleration, ω: the frequency of an oscillatory discharge). Characteristics of water waves are very analogous to the resonance characteristics of the forced oscillatory system consisting of a mass, a spring and a viscous damper. When F0 is equal to about 0.8, wave motions fall into a resonance state. Characteristics of fluid-induced structural loads suggest a possibility that Tainter-gates fall into a self-excited oscillatory state. These theoretically obtained results were proved by experiments.