Abstract
The vibration characteristics of dangerous kind of coupled-mode self-excited vibrations have been investigated in detail using a 1/31-scaled model of Folsom dam Tainter-gate, where it has been revealed that an intensive instability is induced under small gate openings, but never under large gate openings of 14% relative to the gate submergence depth. This paper presents major flow-rate variation characteristics obtained by a 1/27-scaled model of Folsom dam Tainter-gate at its large openings. The reduced gate openings were adjusted at 2 to 8% in its mean value, and the Froude number was from 3 to10. The discharge flow velocity induced by the periodic change of gate opening height was measured along the discharge opening, using an LDV, thus resulting in the resultant fluctuating flow-rate coefficient. As a result, it was concluded that as the gate opening increases, the reservoir flow field is getting released from its tight shutting up the discharge flow, thus resulting in larger fluctuating flow-rate coefficient, but in less dynamic gate instability.
