The effect of the obstacle on the hydraulic response of the composite hydraulic structure

Abstract

Experimental investigations are carried out to study the physics of the flow that passes weir-gate hydraulic structure and encounters obstruction with or without installation of downstream opening. This study approaches the comparison between two different options; the first option deals with free flow condition while the second option deals with submerged flow condition. Various cases are performed considering different hydraulics variables and dimensions variables to evaluate the existence of obstruction with or without openings. Overall the flow pattern is more sensitive to the presence of obstruction at downstream region than in its absence. The hydraulic variables that are considered in the study are divided into dimensional variables such as discharge, downstream flow velocity and water depths at downstream and non-dimensional variables such as discharge coefficient, Froude number and Reynolds number. The obstacles which are used in this study have variable heights with constant width and length. Constant spacing between the obstacles is adopted. Different arrangements of obstacles are considered in this study and it is found that a significant and reasonable result is different among the cases. The effect of rectangular opening in the obstruction on flow pattern is studied. The effect of obstacles with rectangular opening gives a noticeable result in the assessment of the discharge coefficient of the composite hydraulic structure.