Numerical study of the mixing characteristics in an air swirling fluidized bed with monodisperse and multi‐sized particles

Abstract

AbstractPowder mixers are used in many industries. In the present work, a new type of air swirling mixer was designed and optimized with eight horizontally arranged inlet pipes at the tangential inlet angle of 35°. The mixing of multi‐sized spherical particles (2.0, 3.0, 4.0, and 5.0 mm) was numerically investigated in the air swirling mixer by coupled computational fluid dynamics–discrete element method. The numerical results showed that multi‐sized particles achieved comparable mixing performance to monodisperse particles. The Lacey index for multi‐sized particles increased initially, and then reached a maximum value at 0.824. The upward velocity of the particles, , increased initially, and then decreased to zero along the bed height. The maximum value of occurred at a height of 40 mm. Particle radial velocity was larger near the wall than at the mixer tube centre area. The smallest particles aggregated in three layers. The collision number of the particles reached a maximum at bed height of 120 mm, which was consistent with the position of the maximum stress of the particles against the tube wall.