Behavior of compact nonspherical particles in the TSI aerodynamic particle sizer model APS33B. Ultra-stokesian drag forces
- Lovelace Biomedical & Environmental Research Inst., Inc., Albuquerque, NM (United States)
- Winfrith Technology Centre, Dorchester (United Kingdom)
- Warren Spring Lab., Stevenage (United Kingdom)
The aerodynamic behavior of aggregates consisting of uniform polystyrene latex (PSL) spheres and unaggregated cuboidal Natrojarosite particles in a TSI aerodynamic particle sizer (Model APS33B) has been studied. In initial tests, monodisperse PSL microspheres ranging from 0.3 to 7 {mu}m in geometric diameter were generated from aqueous suspensions using a Lovelace nebulizer. APS33B responses for these uniform-sized particles showed multiple peaks. The major (primary) peak, which resulted from the smallest particle, corresponded to the unaggregated single spheres (singlets); the second, third, and fourth peaks were identified as doublets, triangular triplets, and tetrahedral quadruplets, respectively. Both doublets and triplets moved with their long axes in perpendicular (maximum drag) orientation to the flow direction in the APS33B. In contrast, the tetrahedral particles were isomeric and had the same dynamic shape factor (drag resistance) for all three primary orientations. The particle Reynolds numbers (Re{sub p}) for these particles were calculated and ranged from 0.2 to 30 in the sensing volume of the APS33B detector (i.e., ultra-Stokesian conditions). Ultra-Stokesian drag forces for all three types of aggregates were, therefore, estimated and expressed as a function of an empirical factor (1 + aRe{sub p}{sup b}) to the Stokesian drag force. The ultra-Stokesian drag of a Natrojarosite particle was measured in the range 20 < Re{sub v} < 50 and could be described with a similar expression. This approach facilitates the study of the dynamic behavior of nonspherical particles and yields new information about the characteristics of drag forces in the ultra-Stokesian regime. 27 refs., 11 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76EV01013
- OSTI ID:
- 171529
- Journal Information:
- Aerosol Science and Technology, Journal Name: Aerosol Science and Technology Journal Issue: 3 Vol. 19; ISSN 0278-6826; ISSN ASTYDQ
- Country of Publication:
- United States
- Language:
- English
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