Affiliation:
1. Department of Aerospace Engineering, The University of Michigan, Ann Arbor, MI 48109-2140
Abstract
Extinction 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 function 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.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Reference33 articles.
1. Charalampopoulos, T. T.
, 1992, “Morphology and Dynamics of Agglomerated Particulates in Combustion Systems Using Light Scattering Techniques,” Prog. Energy Combust. Sci., 18, pp. 13–45.
2. Faeth, G. M., and Ko¨ylu¨, U¨. O¨., 1995, “Soot Morphology and Optical Properties in Nonpremixed Turbulent Flame Environments,” Combust. Sci. Technol., 108, pp. 207–229.
3. Jullien, R., and Botet, R., 1987, Aggregation and Fractal Aggregates, World Scientific, Singapore, pp. 45–60.
4. Tien, C. L., and Lee, S. C., 1982, “Flame Radiation,” Prog. Energy Combust. Sci., 8, pp. 41–59.
5. Viskanta, R., and Mengu¨c, M. P., 1987, “Radiation Heat Transfer in Combustion Systems,” Prog. Energy Combust. Sci., 13, pp. 511–524.
Cited by
118 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献