The Stability of the Propagation of Sharp Voidage Fronts in Liquid Fluidized Beds

Abstract

Experiments were performed on the propagation and stability of voidage fronts produced by a sudden change in operating conditions. For experiments relatively unaffected by inevitable mal-distribution, the front is stable and propagates in accord with a simple theory. Fronts which are potentially gravitationally unstable were also observed to propagate stably. Linear instability theory, assuming the fluidized mixture to behave as an effective Newtonian fluid, predicts a high degree of instability, in disagreement with experiment. We conclude that the assumption of an effective Newtonian fluid is a poor one.