- - - Graduate of Water Structures, Faculty of Agricultural, Shahrood University of Technology, Shahrood, Iran.
- - - Assistant Professor, Department of Water and Soil, Faculty of Agricultural, Shahrood University of Technology, Shahrood, Iran.
- - - Graduate of Water Structures, Faculty of Agricultural, Shahrood University of Technology, Shahrood, Iran.

Sluice gates are among the flow control structures that are used to measure and control the flow in water conveyance channels. In this research, the geometrical and hydraulic parameters affecting the discharge coefficient of the sluice gate (U-shaped) have been investigated experimentally. The results showed that in the free flow condition, for a constant flow rate, the upstream depth increases with the decrease of the gate opening. Also, with the increase of gate opening, the gate discharge coefficient decreased. For different inlet flow rates, the range of Froude number changes, was from ۰.۰۲ to ۰.۵, which caused the reduction of gate discharge coefficient by about ۵۰%. The results of submerged flow conditions showed that the discharge coefficient increased with the increase of y۱/b ratio. For the range of y۱/b changes from ۰.۵ to ۳, the value of the gate discharge coefficient for different flow rates changed from ۰.۳۵ to ۰.۷. Also, an increase in the upstream Froude number leads to a decrease in the gate discharge coefficient. According to the results, with the increase of y۳/b, for three slopes of zero, ۰.۴ and ۰.۸%, the change trend of Cd was increasing and was in the range of ۰.۵۵ to ۰.۶۵. For gate opening of ۳ cm and flow rates of ۳, ۶, and ۹ m۳/hr, the gate discharge coefficient was obtained ۰.۵۷, ۰.۵۹, and ۰.۶۱, respectively. The slope of the channel bed had no effect on the discharge coefficient of the gate in both free and submerged flow conditions.

Sluice gate, discharge coefficient, U shape channel, free flow, submerged flow