Experimental study on the sand discharge characteristics of a swirling sand dredging device in a reservoir area with multiple mud and sand rivers

Reservoir sedimentation is a globalized challenge. Existing methods for reservoir desilting have certain limitations and often fail to meet the requirements for sand discharge fully. To address this issue, a swirling sediment dredging device has been developed. Through hydraulic model testing, the characteristics of sand removal, erosion, and deposition patterns were examined under various conditions, including flow velocity, water depth, sand depth, and sand gradation. The experimental results demonstrated that the sand discharge efficiency of the swirling device varies significantly with sand deposition states and is influenced by flow velocity. The silt removal effect is optimal when a sand hopper forms, while the application range expands when a sand-washing corridor is created. When a sand flushing funnel forms, both the funnel radius and the sand discharge amount decrease as water depth and sand deposition depth decrease. The sand gradation after the addition of the swirl device closely resembles that of the pre-sand placement, with the funnel radius and sand discharge rate remaining unaffected by particle size. When a sand-washing corridor forms, both the corridor width and sand discharge increase with increasing flow velocity, water depth, and sand depth. Additionally, sand removal is more effective for particles smaller than 0.83 mm in the sand-flushing corridor, with the swirling-flow device having a more pronounced impact. This study clarifies the applicability of swirling sand removal impeller systems under various water and sand conditions, providing valuable insights for practical engineering applications.