Experimental Study of Flow-Induced Vibration of Lens-Shaped Vertical Lift Gates

Abstract

An experimental study of two model-scale lens-shaped vertical gates consisting of a truss and plate is presented. Experimental results are applied to the design of the new Nakdong River gates in Busan, South Korea, for flood and irrigation control. Experimental models are developed using finite-element (FE) analysis. A 1:31 scale model is constructed for the short gate (47.5 m wide, 8.5 m high at full scale) using acrylic, and a 1:61 scale model is constructed for the long gate (95 m wide, 8.5 m high at full scale) using an acrylic truss and acrylonitrile butadiene styrene plate. Natural frequencies of the model gates are measured and calibrated with FE predictions. Dynamic characteristics of the flow-induced vibration are compared for two gate orientations. Vibrations of the model gates in Orientation 1 (plate convex in the upstream direction) and Orientation 2 (plate convex in the downstream direction) are measured for various flow conditions. A combination of bottom opening heights and upstream and downstream water levels is tested in an experimental 1.6-m-wide channel. Hydrodynamic vibrational characteristics of the two experimental gate models are analyzed and compared as a function of upstream (river) level, downstream (sea) level, and bottom opening height. Results from the analysis are used to determine the appropriate gate orientation and incorporated into the final design of the bottom shapes of the prototype gates. The test results also provide a basic dataset for development of operations guidelines to minimize flow-induced vibrations of the gates.