Discharge Estimation from Flap Gates in Rectangular Canals under Free and Submerged Flow

Flap gates are used to measure the flow in canal and are considered as a hydraulic engineering topic, which lacks enough attention so far. Use of flap gate as a measuring tool requires extended studies in order to be recommends as a measuring device for different types of gates. The structures could provide an acceptable economic condition in flow measurement applications where, low costs of manufacturing, installation, and operation could be achieved. This paper presents the discharge estimation from flap gates in rectangular canals under free and submerged flow conditions by using regression and analytical techniques. The derived discharge equations are resulted from the combination of energy and momentum equations. The suggested equations were validated by means of experimental observations, which showed an average error of 1.06% to 1.91% at free flow and 2.28% to 5.26% for submerged flow conditions. The paper also presents some diagrams for estimating the discharge coefficient of flap gates in both flow conditions.