Experimental Study and Numerical Simulation of a Newly Developed Desilting Channel with Swirling Flow

Excessive sediment content during water diversion will lead to a series of engineering problems. In order to solve the problem of water and sediment separation during water diversion of sediment-laden rivers, sediment discharge facilities are often set at the channel head. As a new channel sediment discharge technology, the comprehensive performance and sediment discharge effect of the desilting channel with swirling flow are the key to its popularization and application. In this paper, the experimental study and numerical simulation are used to analyze the hydraulic characteristics and sediment discharge characteristics of the flow in the desilting channel with swirling flow. Firstly, according to the physical model, the experiment was carried out to obtain the corresponding hydraulic parameters and sand interception rate. Secondly, the accuracy of the numerical simulation is verified by the parameters obtained from the experiment. The numerical simulation results of the parameters such as flow velocity and water surface profile are consistent with the experimental values, and the numerical simulation can reflect the movement state of the flow in the desilting channel with swirling flow. Finally, combined with the model test and numerical simulation, the hydraulic characteristics and sediment discharge characteristics of the desilting channel with swirling flow are comprehensively analyzed. The results show that the flow pattern in the swirling flow generator is in the evolution sequence of free flow, critical flow and submerged flow with the increase of channel inflow. Under the submerged flow pattern, the rotating flow can be formed in the sediment discharge tunnel, which is beneficial to the suspension and uplifting of sediment and has little influence on the flow pattern in the diversion channel. With the increase of the water depth in the upstream channel, the diversion ratio of the sediment transport pipe decreases nonlinearly. When the relative water depth is 0.97, the diversion ratio of the sediment discharge tunnel is only 6.07%. When the relative water depth is 0.21, the maximum velocity in the desilting tunnel is increased by 175% compared with the average velocity in the channel, and the sediment interception rate for the sediment of the particle size of 0.075 mm～3.000 mm reaches 93.7%. In summary, the desilting channel with swirling flow is a channel sediment discharge technology with high sediment discharge rate and low water consumption. The results enrich the study of water and sediment separation technology in water diversion projects, and provide a new idea for solving the problem of channel sediment deposition. © 2022 Editorial Department of Journal of Sichuan University. All rights reserved.