Optimization of structural parameters for the pneumatic conveying device of dried safflower filaments based on CFD-DEM coupling

To address the issues of low conveying efficiency and high energy consumption in the pneumatic conveying of dried safflower filaments, this study established a discrete element model (DEM) of dried safflower filaments and coupled it with Computational Fluid Dynamics (CFD). The conveying mechanism and the synergistic regulation effects of key structural parameters—side-wall inclination ( θ ), tail opening ratio ( ψ ), and transition section length ( L t )—on gas-solid flow characteristics were investigated. Results indicated that the coordinated regulation of these structural parameters significantly enhanced airflow velocity and material carrying capacity. Specifically, compared to the baseline rectangular pipe ( θ = 90 ∘ ), the optimized device achieved an increase of 192.2% in the average conveying rate and a 98.6% improvement in the specific pressure drop conveying capacity. A multi-objective optimization was conducted using Response Surface Methodology (RSM). The optimal combination was determined as θ = 133.7 ∘ , ψ = 0.75 , and L t = 80.9 mm. Bench validation experiments indicated that the optimized device achieved an average conveying rate of 130.36 g/s and a specific pressure drop conveying capacity of 0.044 g·s⁻¹·Pa⁻¹, with relative errors of 8.68% and 12.53% compared to simulations. This study provides a theoretical basis for the low-loss and high-efficiency design of pneumatic conveying systems for agricultural materials.