Simulation of powder distribution in IITRI bag experiments

A two-dimensional transient computer program developed for fluidization was used to study the uniformity of powders injected into rectangular cavities. Most configurations gave very non-uniform powder distributions. Simulation of a leak present in the experimental bag experiments produced a jet expansion not unlike that observed in photographic records. Simulations with 5, 30 and 200 micron powders showed that the jet expansion was most pronounced with 5-micron powders, and that the powder distribution was the most uniform of the configurations studied. A comparison of experimental concentration contours obtained from the high-speed photographic records of powder injection showed a reasonably good agreement with the theory. The agreement is considered good, because the theory has no fitted parameters. It is predictive. Discrepancies between the theoretical and experimental results may be qualitatively accounted for by bag expansion and a reduced pressure in the bag due to leaks.