Gate Vibration Research Articles

Discussion of “Spillway Gate Vibration on Arkansas River Dams”

Discussion of “Spillway Gate Vibration on Arkansas River Dams”

Spillway Gate Vibration on Arkansas River Dams

Spillway tainter gates are susceptible to flow induced vibrations particularly when the gate lips are submerged by tailwater levels. Vibrations experienced on the spillway gates of the Arkansas River Navigation Project were severe enough to cause cracks in the structural members and welded connections of the gates. The nature, patterns, and magnitude of the vibrations on these gates were determined and related to the gate openings, tailwater levels, lip designs, seal designs, structural rigidity, and several other factors. Lip design, rubber seal design, and structural flexibility were concluded to be the major causes of gate vibrations. Factors which should be considered in future tainter gate designs to provide vibration-free operation include: (1) lip designs with a clean, sharp flow breakoff point; (2) elimination of rubber gate bottom seals wherever possible; (3) structurally rigid gate lip designs; and (4) testing of unusual gate designs to check for vibration tendencies.

Mossyrock Arch Spillway

Design of the Mossyrock spillway on the Cowlitz River for the Department of Public Utilities of the City of Tacoma required careful selection of the spillway arrangement to be used in order to dissipate 11,000,000 hp of energy from a flow of 276,000 cfs falling 340 ft within a limited area of a deep, narrow gorge. A combination of warped buckets and plunge pool was selected to dissipate the energy. Hydraulic model tests were conducted to verify and modify the design, where necessary, in order to provide a final design for the spillway system. The spillway went into operation in November, 1968; maximum gate opening to date was 5 ft to 6 ft. The flow conditions for the spillway openings were good and were as predicted in the model; no air-entraining vortices or gate vibrations were noticed.

Prototype investigations of dynamics of a triple-rib of a plane gate of the dam of the XXII Congress CPSU Volga Hes

1. The frequency of free vibrations of ribbed gates in the air and the magnitude of the affected water mass when the gate is immersed in water are amenable to quite simple and sufficiently accurate calculations. For gates similar to those discussed it is permissible to determine ν0 as for a beam supported at the ends with shear deformation taken into account. It is recommended that the affected water mass be computed by Eq. (1) and a coefficient K=0.4. 2. Gates with clearly expressed ribbing (i. e., such in which almost the entire mass and rigidity are concentrated in several planes-planes of widely separated ribs connected with transverse ties of slanting type) are characterized by independent dynamic operation of the ribs as independent vibrating systems. The hypothesis of geometrically unchanging transverse ties is confirmed in static calculation: its application in dynamic computation when the determining role is played by inertial forces does not reflect the physics of the actual process. Having determined the natural frequencies of each of the ribs one can consider the average value as the natural frequency of the gate. 3. As a result of the investigation it was found that owing to the presence of a reverse relation between the pulsation of pressure and pulsation of the bar the system of the gate in water exhibits a tendency toward hydroelastic autovibration processes of natural frequency. Therefore, the determination of inherent vibration characteristics of the gate becomes of special importance in its design.

Closure to “Vibration of Gates During Overflow and Underflow”

Closure to “Vibration of Gates During Overflow and Underflow”

Vibration of Gates during Overflow and Underflow

Violent vibrations may occur at dam or weir gates being subjected simultaneously to overflow and underflow; model studies have been made to evaluate frequency and magnitude of exciting forces for different types of gates and aprons; design criteria and basic mechanism of excitation are presented.

Vibration of Gates During Overflow and Underflow

Violent vibrations may occur at dam or weir gates being subjected simultaneously to overflow and underflow; model studies have been made to evaluate frequency and magnitude of exciting forces for different types of gates and aprons; design criteria and basic mechanism of excitation are presented.