Theoretical and experimental study of flow from sluice gates

The discharge coefficient of sluice gates in free and submerged conditions plays an important role in determining the flow rate past such structures. The effects of relative gate opening and submergence ratio have been widely considered by several investigators, mainly based on experimental work. Most of this work, however, lacks an analytical approach to include the variation of discharge coefficient as influenced by gate opening and submergence ratio. This paper, using energy and momentum conservation theory, presents an analytical method to determine the contraction ratio and discharge coefficient of sluice gates under free and submerged flow conditions. Based on suggested relationships for the contraction ratio, variations in energy loss under free and submerged flow and the submergence limit are determined and some graphical demonstrations are adapted. The results are compared with experimental data reported by several investigators and show good agreement.