Investigation of Free Flow under the Radial Gate with the Sill

Due to the water shortage in developing countries, increasing the hydraulic performance and increasing the efficiency of water distribution in irrigation networks is necessary. One of the strategies for improving the efficiency of agricultural water productivity is increasing the accuracy of discharge measurement and controlling the water level. Gates are needed in order to control the amount of water released from dams and for regulating the water level in irrigation networks. There are different types of gates and the most common types of gates are sluice gates and radial gates. Gates are used widely in irrigation networks; therefore choosing small dimensions for the gates can reduce the channel costs. One of the ways for reducing the dimensions of the gate is to create a sill at the bottom of the canal and install the gate on the sill, so the design height of gate is reduced and it’s economically affordable. Estimation of the discharge coefficient of gate and consequently the amount of flow is one of the most important issues in hydraulic. The coefficient of discharge for free flow radial gates without the sill depends on the upstream water level and the gate opening (Bos, 1989). The objective of this paper is to investigate the effect of characteristics of sill such as the shape, height and location on the discharge coefficient for free flow radial gates. To achieve this goal, first the Flow-3D model’s output results for simulation of flow passing through a radial gate are validated using the experimental data and then the effect of the sill on the flow passing through a gate is examined.