Abstract: Desilting basin is one of the important facilities to ensure the normal operation of drip irrigation system. However, the solid-liquid coupling process of water and sediment in the basin during irrigation is complex, and it is difficult to optimize the structure by a single physical model. In order to boost the deposit efficiency of drip irrigation system, we designed a long channel straight-line desilting basin. Through physical experiment and numerical simulation, we examined the influences of flow-adjusting board and the angle of the flow-adjusting board on flow and sediment movement. Results manifest that the solid-liquid coupling process in the basin can be simulated accurately by Fluent software; the flow-adjusting board designed in the back basin plays the role of energy dissipation, speed reduction and improvement of sediment settling rate by reducing the flow velocity by above 70% and enhancing the sediment setting rate by over 12% compared with that in the absence of flow-adjusting board. In addition, when the inclined angle of flow-adjusting board is 60°, the flow velocity in the basin drooped to the lowest, while sedimentation rate hit the highest; the minimum sediment concentration at the outlet was 1.12 g/L, and the sedimentation rate averaged at 71.26%. The research findings offer technical support for optimizing hydraulic structure and improving the efficiency of desilting basin.

Key words: sedimentation basin, sediment characteristics, numerical simulation, adjusting-flow board, sediment settling rate