Air pressure reversal within vibrating particle beds

Abstract

Measurements were made of the air pressure at the bottom and along one side of vibrating particle beds. Glass beads of mean diameters of 99, 227 and 332 μm were used, and the static bed height was varied between 60 and 150 mm. Over one vibratory cycle, the peak air pressure at about 40-50 mm from the top (in beds of 99 μm glass beads) was always the highest; higher than that at the vessel base; the position of the maximum air pressure moved upward with increasing bed height. This unusual pressure reversal was observed to occur in beds of greater heights with larger glass beads. In conjunction with this air pressure reversal, the dependence of the instability of vibrating particle beds on particle size was examined through calculations of the interparticular normal vertical stress.