Analysis of Aerosol Aging in the Rotating Drum Chamber
Abstract
Two of the most recent theories describing aero-sol mechanics in the rotating drum chamber were compared with experimental measurements. Both theories predicted nearly the same results but did not match out measurements. Possible causes for the discrepancies were investigated, and it was found that convective diffusion accounts for the difference with the stirred settling model predicting measurements reasonably in the limit where rotation rate becomes zero. Once rotation begins, transport by diffusion was found to dramatically decrease, probably because convective currents gyrate driving smaller eddies that experience rapid viscous dissipation. Damping of convective diffusion was found to be sufficient for transport to be dominated by centrifugal acceleration three orders of magnitude smaller than gravity acting on particles several microns in diameter. Finally, the discrepancies at nonzero rates of rotation were explained by triboelectric charging during dissemination, which can normally be ignored during static chamber tests governed by convective or strong turbulent diffusion transport up to a laminar boundary layer where gravitational settling dominates. When the drum was rotated, transport by the repulsive coulombic force between a triboelectric charged particle and the monopolar charged aerosol cloud dominated transport by centrifugal acceleration.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2005
- Accession Number
- ADA442793
Entities
People
- Janon F. Embury
- Tiffany A. Sutton
Organizations
- Edgewood Chemical Biological Center