The Effects of Multi-Gates Operations on the Flow Fields near the Downstream of Outlet

• Main Authors: Ching-HoHsu, 許清河
• Other Authors: Jan-Mou Leu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/64013713810255409682

碩士 === 國立成功大學 === 水利及海洋工程學系專班 === 100 === ABSTRACT Numerical simulations of flow fields at downstream of the Outlet of multi-gates under operations were presented. The previous studies are limited on the effects of multi-gates operations on the flow fields downstream of the gate-outlet. Emphasis of the present study is given to the relation between the flow fields and multi-gates operations. A two-dimensional hydraulic model was applied to simulate the flow fields downstream of the gate-outlet. The three kinds of gate setup and two kinds of operation procedure were investigated. The velocity fields and bed shear stress distributions were presented. The links between setup of the gates and operation procedures, as well as the flow fields, are crucial factors in the sediment movement because they can improve our understanding of sediment transport around downstream of the multi-gates. In the cases with the multi-gates opening at the same time, the lengths of the re-circulation zone were about 2.0, 1.7, and 1.3 times the width of gate outlet for cases1, 3 and 5 respectively. In the cases with the multi-gates operation, the lengths of the re-circulation zone were about 1.5, 1.2, and 1.1 times the width of gate outlet for cases1, 3 and 5 respectively. With vertical windwalls (cases 1 and 2), the results of the bed shear stress indicate the shear stresses are concentrated at the areas near the central of the river channel. Once oblique windwalls installed (cases 3, 4, 5 and 6), the values of bed shear stress drops and the areas with high bed shear stress decreases. The flow fields also reveal that the values of bed shear stress and the areas with high bed shear stress can be reduces by the operations of multi-gates. Keywords: Gate, Operation, Numerical Simulation, Bed Shear Stress.