Measurement of Two Kinds of Granular Temperatures, Stresses, and Dispersion in Bubbling Beds

A CCD camera technique was developed to measure instantaneous particle velocities in a thin bubbling bed for fluidization of 530 μm glass beads. The hydrodynamic velocities were computed by averaging the instantaneous velocities over the velocity space using the concepts of kinetic theory. Laminar-type kinetic stresses and granular temperatures were computed from the measurement of instantaneous velocities. Bubblelike granular temperatures were computed from the hydrodynamic velocities. The measured Reynolds normal stresses per unit bulk density in the vertical direction were 8 times larger than the measured Reynolds normal stresses per unit bulk density in the lateral direction because of higher velocity fluctuations for particles in the bubble-flow region. The sum of the measured shear stresses was equal to the pressure drop minus the weight of the bed of solids within experimental error. The restitution coefficients for 530 μm glass beads, estimated from the ratio of shear to normal stresses, are in th...