AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Shear Induced Mixing of Laminar Flows: Implications for Aerosol Measurements
MATTHEW BROWN, Suresh Dhaniyala, Clarkson University
Abstract Number: 246 Working Group: Instrumentation and Methods
Abstract Most widely used aerosol instruments rely on a common flow design to achieve highly sensitive measurements. The flow arrangement typically is composed of two concentric laminar flows that merge together in a measurement region, as in a Differential Mobility Analyzer (DMA) or an optical particle counter. When the flows merge, it is assumed there is no particle mixing or dispersion, resulting in diluted flow. For accurate aerosol measurements under a range of operating conditions, it is important to verify this assumption. In this study, we designed an experimental setup to obtain near axi-symmetric concentric flows and determined the extent of particle mixing under various shearing velocity conditions. The mixing characteristics were then obtained as a function of the relative velocity ratios of the two flow streams upon introduction. The experimental results suggest that there is a strong correlation between the extent of particle mixing and the velocity ratio of the flows. The results of this study are used in conjunction with aerosol transport modeling to relate measurement accuracy (sizing with a DMA or an optical particle counter) to its operating conditions. The experimental results of flow mixing and the implications for particle measurements will be presented.