Analysis of Flow Over Weir and Under Ellipse Gate

Abstract

Combined hydraulic structures are widely used in irrigation system for civil engineering water system works. The use of gate have regular shape is commonly used in hydraulic structures because it is easy to construction as compare with non-regular shape. The aim of this study is to investigate the effect of use gate have non-regular shape especially half ellipse shape with three different shape of weir such as rectangular, triangular and parabolic weir. This study concentrates on the effect of cross sectional area of flow that passes through ellipse gate on hydraulic parameter like flow rate, discharge coefficient, downstream water depth, and water surface profile shape and level. The present study addressed the aspect of geometrical dimension effect on hydraulic parameters. Also this study mention to the effect of Reynolds number on hydraulic variables such as flow rate and cross sectional area of flow that passes the gate. The present study concluded that it is better to use non-regular shape of gate in combined hydraulic structure with any shape of weir. Also, it is observed that it is favored to use non-regular shape for both gate and weir in construction of combined hydraulic structure due to their significant effect on discharge quantity and depth of water in downstream of flume or open channel in field taking in consideration that the water surface profile is always nonlinear.

Keywords: Hydraulic structure, half ellipse gate, parabolic weir, rectangular weir, triangular weir. Free flow condition.