Numerical simulation on movement behaviours of cylindrical particles in a circulating fluidized bed

摘要

The movement behaviours of cylindrical particles in a circulating fluidized bed were studied with a three-dimensional multi-way coupled model of cylindrical particle flow. In this model, the translation and rotation of individual cylindrical particles were solved directly by Newton-Euler dynamics. The interaction between cylindrical particles was handled in line with rigid impact dynamics and the modified Nanbu collision probability method. The coupling algorithm between the motion of cylindrical particles and turbulent flow was disposed using the correlation between Lagrangian time scales and the k-E closure model. Numerical simulation indicates that cylindrical particles in the near-wall region reach the exit of the riser faster than those in other regions. The majority of collisions between cylindrical particles occur in the annular region between the central and near-wall regions. In the horizontal direction, the horizontal velocity components of cylindrical particles vary slightly and distribute randomly, whilst the vertical velocity component exhibits produced variation from the near-wall region to the central region. Further, the rotation of a cylindrical particle around its axis is shown to be significantly weaker than those around the two other orthometric axes. The collisions of cylindrical particles affect the distribution of horizontal velocity components of cylindrical particles more evidently.