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 κ–εmodel. 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 κ–ε 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.
Keywords: gas–solid two-phase flow of cylindrical particles, two-way coupling correlation, rigid dynamics, fluidization properties.