On the Dynamics of a Quasi-Two-Dimensional Pulsed-Fludized Bed

TL;DR

This paper investigates how pulsed fluidization influences bubbling patterns and granular dynamics in a quasi-two-dimensional bed, revealing energy redistribution between modes as gas frequency varies.

Contribution

It provides experimental insights into the relationship between pulsing parameters and granular flow patterns using Proper Orthogonal Decomposition analysis.

Findings

Energy shifts between harmonic and sub-harmonic modes with frequency change

Bubbling pattern alterations linked to particle motion modes

Granular rheology changes with bubbling dynamics

Abstract

Periodic fluidization of solids in a gas medium can generate structured bubbling patterns. This phenomenon has been successfully reproduced in fluidized bed systems called pulsed-fluidized beds, known for their efficient mixing and tunability. The resulting pattern depends on particle properties, dimensions of the bed, mean inlet velocity, bed height, and amplitude and frequency of pulsing. It is however important to understand the changes in granular rheology associated with bubbling patterns. In the experimental work presented, we report on the results from a small-scale quasi-two-dimensional pulsed-fluidized bed. Proper Orthogonal Decomposition analysis applied to Particle Tracking Velocimetry data reveals a redistribution of energy between the harmonic and sub-harmonic modes as the inlet gas frequency is decreased. The change in bubbling pattern is accompanied by a change in granular dynamics due to the dominant modes of particle-phase motion.