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Extinction and Scattering Properties of Soot Emitted from Buoyant Turbulent Diffusion FlamesExtinction and scattering properties at wavelengths of 250-5200 nm were studied for soot emitted from buoyant turbulent diffusion flames in the long residence time regime where soot properties are independent of position in the overfire region and characteristic flame residence times. Flames burning in still air and fueled with gas (acetylene, ethylene, propane, and propylene) and liquid (benzene, toluene, cyclohexane, and n-heptane) hydrocarbon fuels were considered. Measured scattering patterns and ratios of total scattering/absorption cross sections were in good agreement with predictions based on the Rayleigh-Debye-Gans (RDG) scattering approximation in the visible. Measured depolarization ratios were roughly correlated by primary particle size parameter, suggesting potential for completing RDG methodology needed to make soot scattering predictions as well as providing a nonintrusive way to measure primary soot particle diameters. Measurements of dimensionless extinction coefficients were in good agreement with earlier measurements for similar soot populations and were independent of fuel type and wavelength except for reduced values as the near ultraviolet was approached. The ratios of the scattering/absorption refractive index functions were independent of fuel type within experimental uncertainties and were in good agreement with earlier measurements. The refractive index junction for absorption was similarly independent of fuel type but was larger than earlier reflectometry measurements in the infrared. Ratios of total scattering/absorption cross sections were relatively large in the visible and near infrared, with maximum values as large as 0.9 and with values as large as 0.2 at 2000 nm, suggesting greater potential for scattering from soot particles to affect flame radiation properties than previously thought.
Document ID
20030016509
Acquisition Source
Glenn Research Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Krishnan, S. S.
(Michigan Univ. Ann Arbor, MI United States)
Lin, K.-C.
(Michigan Univ. Ann Arbor, MI United States)
Faeth, G. M.
(Michigan Univ. Ann Arbor, MI United States)
Yuan, Z.-G.
Urban, D. L.
Yuan, Z.-G.
Date Acquired
August 21, 2013
Publication Date
April 1, 2001
Publication Information
Publication: Journal of Heat Transfer
Publisher: American Society of Mechanical Engineers
Volume: 123
Subject Category
Inorganic, Organic And Physical Chemistry
Funding Number(s)
CONTRACT_GRANT: NIST-60NANB4D-1696
CONTRACT_GRANT: NAG3-2048
CONTRACT_GRANT: NIST-60NANB8D0084
CONTRACT_GRANT: NAG3-1878
Distribution Limits
Public
Copyright
Other

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