Study on two-way coupling of gas-solid two-phase flow of cylindrical particles

This article proposed a three-dimensional model of gas-solid two-phase flow of cylindrical particles based on Discrete Element Method (DEM), Rigid Dynamics and K-epsilon model. In this model, the two-way coupling correlation between cylindrical particles and turbulent flow was established according to the correlation between Lagrangian time scales and k-epsilon model, the force and motion model of cylindrical particles was established according to Rigid Dynamics, and the inter-cylindrical particle collision was taken into account by using the Rigid Impact Dynamics and modified Nanbu collision method. The model was verified by a cold-state experiment of gas-solid two-phase flow of cylindrical particles in a fluidized bed. In addition, some fluidization properties of gas-solid two-phase flow of cylindrical particles were obtained. Experiment results and simulated results both proved that the axes of most cylindrical particles are closely parallel to z-axis when cylindrical particles move up in the riser during the fluidization; there is an evident horizontal transfer of cylindrical particles from radial central regions to near-wall regions during the fluidization, and the number concentration of cylindrical particles in radial central regions is lower than that in near-wall regions. Simulated results showed that the volume fraction of turbulent flow in radial central regions is higher than that in near-wall regions and it will change evidently over time; the velocity and pressure of local turbulent flow field will decline evidently where there is a residence of some cylindrical particles. (C) 2016 Elsevier B.V. All rights reserved.