Document Type

Thesis

Date of Award

10-31-1993

Degree Name

Master of Science in Mechanical Engineering - (M.S.)

Department

Mechanical and Industrial Engineering

First Advisor

Rosato, Anthony D.

Second Advisor

Dave, Rajesh N.

Third Advisor

Fischer, Ian Sanford

Abstract

Size segregation imposed by vibration or shaking is an ubiquitous phenomenon whereby a large particle will rise to the top of a bed of smaller spheres upon vibration. Several mechanisms based on computer simulations have been proposed, however a complete theory remains elusive. The objective of this study was to perform experiments to study vibratory segregation of particles for varying size ratios and vibration parameters. More specifically, the rise time of a sphere from the bottom to the top of a vibrated bed was examined. It was found that the rise time decreased with an increase in amplitude for fixed frequencies. In addition, an increase in frequency led to a decrease in rise time for fixed amplitudes. Also, particles of all diameter ratios, including unity, rose to the top of the vibrated bed. Large diameter ratios showed a decrease in rise time when compared to that of smaller diameter ratios. It was found that convective flows within the vibrated system have a strong influence on the rising particles. Based on these findings, conclusions were drawn which lead to a hypothesis explaining the difference in rise time for different diameter ratios in a vibrated bed.

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