CFD Simulation of Bed Collapse in 3D Fluidized Beds

摘要

Multiphase Computational Fluid Dynamics (CFD) has become an alternative method to experiments for understanding the fluid dynamics in gas-solid fluidized beds. A two-fluid model, which contains additional terms in both the gas- and solid-phase momentum balances, is employed to investigate the bed collapse process in three-dimensional beds. In this model, only a correlation for drag force is necessary to close the governing equations. Transient calculations have been made in the platform of CFX 4.4 by adding User-defined Fortran subroutines. A case study for sand with a density of 2500 kg/m~3 and a mean diameter of 610 urn, belonging to Geldart B classification, is simulated in a rectangular duct of 0.2 m (long) × 0.2 m (wide) × 0.5 m (high). The collapse process is numerically analyzed by considering the standard deviation of the surface between the dense phase and freeboard, which is generally in fair agreement with the classic theory of Geldart.