Hydraulic performance of elliptical-LOPAC gate under submerged flow conditions

This study intended to investigate the hydraulic performance of the new types of LOPAC gates, namely the elliptical LOPAC (EL) gate, and the rectangular LOPAC (RL) gate for irrigation canals. To that end, 90 experiments were carried out at three different flow discharges (25, 35, and 45 l/s), three different submergence ratios (y2/y1 = 0.7, 0.8, and 0.9) and five different gate opening angles (35, 40, 45, 50, and 52.5°). In the EL gate, as the submergence ratio decreased by 20%, the maximum increase in Cd for the discharges of 25, 35, 45 l/s at 52.5° of gate opening angles happened in the order of 0.426, 0.475, and 0.506, respectively. Moreover, the maximum decrease ratios in ΔE/E1 followed by 20% increase in the submergence ratio for the same discharges at 35° of gate opening angles were 0.195, 0.1944, and 0.1922 respectively. Finally, the empirical rating curve and equations were proposed to predict Cd and ΔE/E1 for both the EL and RL gate models. For the EL gate, the RMSE ratios for the proposed Cd and ΔE/E1 equations were obtained 0.0027 and 0.0021 respectively.