AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Modeling Cross-flow Aerosol Mixing under Moderate Reynolds Number
MATTHEW BROWN, Yi-wen Huang, Daniel Cziczo, Suresh Dhaniyala, Clarkson University
Abstract Number: 540 Working Group: Aerosol Physics
Abstract Aerosol experiments often require the conjoining or mixing of two flows – typically a particle-laden flow and a clean sheath flow or sometimes two particle laden flows. Examples of such flow systems include: the aerosol injection region in the DMA, where aerosol and sheath flows mix, aerosol sheathing flow, such as in optical instruments, or mixing of aerosol and clean flows in aerosol diluters. The interaction of such flows is often under conditions of moderate Reynolds numbers of less than 1000. While there is sufficient fundamental understanding of the behavior of flows at low Reynolds numbers and there is some experimental knowledge of turbulent behavior of aerosols under very high Reynolds number, our knowledge of flow mixing behavior at moderate Reynolds numbers and their implication for aerosol mixing is largely unknown. In the present study, experiments and computational modeling are used to determine the influence of flow mixing conditions, such as velocity ratios and bulk flow Reynolds numbers, on particle dispersion characteristics. Experiments are conducted with a bench-top setup to inject size-selected particles perpendicularly into a clean flow and the radial distribution of particles is determined from multi-angle concentration measurements downstream of the mixing region. Initial results suggest that, even under moderate Reynolds numbers, turbulent mixing of particles is possible when the velocities of the cross-flow streams are comparable. By matching computational particle transport modeling results with experimental data for identical operating conditions, particle size-dependent turbulent interaction parameters are determined. Details of the experiments and modeling approach used in the current study will be presented and implications for design of aerosol mixers and sheath flow devices will be described.