Abstract

We use a virtual Couette rheometer to study the behaviour of dry and wet granular materials in aerated bed. A typical fluidization curve for dry powders exhibits fixed bed characterized by linear increase in pressure drop with increasing air velocity. This is followed by a fluidized bed at a constant pressure drop with further increase in air velocity. However, wet powders display different aeration behaviour due to the inhomogeneous gas flow through the bed. The fluidization behaviour of the powder upon addition of small amounts of silicon oil liquid has been tested for two different grain sizes. We distinguish different regimes of fluidization for wet powders with different saturation of silicon oil and different grain sizes. Further, we compare the hysteresis effects in fluidization and de-fluidization cycles of the materials. We also compare the shear stresses and study the rheology of the materials under different fluidized condition.