Predicting Discharge Coefficient of Triangular Side Orifice under Free Flow Conditions

Weirs, orifices, baffle sluice gates, and sluice gates are widely used in irrigation networks for distributing water from the source to irrigated areas. Side orifices are generally placed in the side of a channel for diverting some of the source channel flow. Prediction of the discharge rate through side orifices of different shapes is important in irrigation and hydraulic engineering. The hydraulic behavior of side triangular orifices (Δ-shape orifices) has not been studied either experimentally or theoretically. In this study, sharp-crested side triangular orifices are studied experimentally and analytically. Several models are derived for the discharge coefficient based on Buckingham’s theorem of dimensional analysis. A series of laboratory experiments (570 runs) were performed to investigate the flow discharge through side triangular orifices located in horizontal rectangular channels under free flow conditions. Using the collected data in the present work, proposed models were calibrated. One model that includes the approach Froude number has an average error of 2.1%, while a second model that does not include the approach Froude number has an average error about 3.3%. Therefore, actual discharge through the side triangular orifices can be accurately estimated using the proposed models.