Experimental and theoretical measurement of the aerodynamic diameter of irregular shaped particles.

Details

• Personal Author:
  Marple VA ; Rubow KL ; Zhang Z
• Description:
  A theoretical technique for determining equivalent aerodynamic diameters (EAD) of irregularly shaped particles was developed and verified experimentally. High speed computers were used to solve two dimensional and three dimensional Navier Stokes equations on spheres, cylinders, disks and cubes. In all cases, calculated values agreed within 5% of reported experimental values. Three dimensional algorithms were then used to determine flow fields around irregularly shaped particles. These values were used to determine drag force, fRom, William N.hich EAD could be calculated. Experimental verification was done using coal, silica and talc particles, 1 to 4 microns in diameter, analyzed using a spiral duct centrifuge and scanning electron microscopy (SEM) with two dimensional orthogonal shadowing. The centrifuge separated irregular particles based on size and orientation. In SEM, particles were shadowed with gold film in two orthogonal directions at a 15 degree angle. This provided shape and size parameters in three dimensions. The numerical calculation defined particles as groups of blocks around which flow fields were calculated. From these, drag force and EAD values were determined. Theoretical and experimental values revealed good agreement. Particle orientation contributed variations of as much as 17% in measured diameters, and this could be accurately calculated by the numerical technique. The authors conclude that the theoretical technique is a powerful tool for determining EADs of irregularly shaped particles in any orientation.
• Subjects:
  Accidents, Occupational Amines Carcinogens Coloring Agents Hydrocarbons Neoplasms Occupational Health Polycyclic Aromatic Hydrocarbons Risk Assessment Safety
• Keywords:
  Aerosol Particles Analytical Methods Analytical Models Coal Dust Computer Models Microscopic Analysis Physical Properties Silica Dusts Talc Dust
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Genre:
  Conference/Symposia Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  663-667
• NIOSHTIC Number:
  nn:00198848
• Citation:
  Proceedings of the VIIth International Pneumoconioses Conference, August 23-26, 1988, Pittsburgh, Pennsylvania, USA. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 90-108, 1990 Sep; (Pt I):663-667
• Federal Fiscal Year:
  1990
• Peer Reviewed:
  False
• Part Number:
  I
• Source Full Name:
  Proceedings of the VIIth International Pneumoconioses Conference, August 23-26, 1988, Pittsburgh, Pennsylvania, USA
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:41f8c847e2e63091aefa108180717b83f91f59e3a44ae398bea5c1704a47cfef63ed515dcbcbe922dd5919f38ce8ed21d54097218c9e9b608fba0c7588d344ff
• Download URL:
  https://stacks.cdc.gov/view/cdc/180681/cdc_180681_DS1.pdf
• File Type:
  [PDF - 199.85 KB ]