Experimental and numerical analysis of combined weir-gate flow in lateral flows

Flow measurement and level control in open channels are important to support the management of the hydraulic structure system. Side weirs are an important hydraulic structure used for purposes such as taking a certain amount of flow from a channel, evacuating excess water to regulate the water height. Many studies have been carried out in the literature on classical and labyrinth side weirs and gates in straight channels. It is important to experimentally investigate the flow characteristics of both weir and gate structures and to determine the flow characteristics of a combined side weir-gate structure. Although combined weir-gate structures are commonly used for frontal flows in hydraulic structures, the same is not true for lateral flows. Therefore, in the present study, the hydraulic characteristics of combined weir-gate structures were investigated experimentally and numerically for lateral flows in a straight channel. Several experiments were cconducted for side weirs and gates with the same geometries to better analyze the combined side weir-gate structures. Flow-3D was used. The k- turbulence model was used as the turbulence model. Extensive experiments were carried out in the subcritical flow conditions with 0.06, 0.09 and 0.12 m crest height side weir, gates and combined side weir-gate models with different flow conditions, geometries, and types. The parameters affecting the discharge capacity of the side weir, gate and combined side weir-gate structures were determined by dimensional analysis. The characteristics of the combined flow were examined in detail based on the obtained dimensionless parameters. In this study, 770 experiments were conducted to determine the flow characteristics of the combined side weir-gate for subcritical regime. Experimental results were analyzed to determine the effect of effective dimensionless parameters on the discharge capacity of the combined weir-gate structure. The interaction factor of the combined side weir structure is determined that it depends on the upstream Froude number, the ratio of the gate opening to the upstream flow depth, the ratio of the vertical distance between the top of the gate and the weir crest to the gate opening, and the ratio of the gate or weir length to the upstream flow depth and the ratio of the weir or gate length to the main channel width. Discharge capacity of combined side weir-gate is higher than classical rectangular side weirs and side gates. Nonlinear equations were developed for the discharge of the combined side weir-gate structure, and the reliability analyzes of the obtained equations were made. It has been observed that there is a very good agreement between the data obtained from the numerical study and the experimental study data. It has been seen that the mean error rate value for all combined side weir-gate models is 2% and it is concluded that numerical analysis methods are applicable for combined side weir and valve structure.