Yanchun Kang, Xuefeng Song, Ruichi Luo, Taijin Huang, Feng Xiao, Zekang Deng, Huhu Chen
Pneumatic conveying of threshed corn residual products, which represent a typical binary heterogeneous system comprising corn kernels and corncobs, plays a critical role in the seed industry but frequently encounters blockage issues at 90° vertical elbows. To clarify the microscopic blockage mechanism and optimize transport efficiency, this study utilizes a coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach. In contrast to traditional spherical simplifications, a high-fidelity multi-sphere cluster method is employed to faithfully reconstruct the irregular rod-like morphology of corncobs. Simulation results reveal a unique blockage mechanism in the reacceleration zone downstream of the elbow. Specifically, irregular corncobs experience significantly higher aerodynamic drag and rotational energy dissipation than spherical kernels due to tumbling behavior. This disparity leads to a distinct "velocity lag" and subsequent aerodynamic segregation. Furthermore, a Box-Behnken design was implemented to analyze the effects of pipe diameter, airflow velocity, vertical height, and material feed rate. A significant interaction effect between pipe diameter and airflow velocity was identified ( P < 0.05). The optimization results indicate that a minimum pressure drop of 99.371 Pa is achieved at a pipe diameter of 500 mm, an airflow velocity of 20 m/s, a vertical height of 3000 mm, and a material feed rate of 5 kg/s. These findings provide a theoretical basis for low-damage transport and offer conservative design criteria applicable to complex pipeline networks. • CFD-DEM model simulates binary transport of kernels and cobs. • Centrifugal force causes distinct segregation of cobs at elbows. • Irregular cobs show intense coupling force fluctuations compared to kernels. • Diameter and velocity interaction significantly affects pressure drop. • Optimized parameters minimized pressure drop to 99.37 Pa.