Investigation of in-flame soot optical properties in laminar coflow diffusion flames using thermophoretic particle sampling and spectral light extinction

Nathan J. Kempema, Bin Ma, Marshall B. Long

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11 Scopus citations

Abstract

Soot optical properties are essential to the noninvasive study of the in-flame evolution of soot particles since they allow quantitative interpretation of optical diagnostics. Such experimental data are critical for comparison to results from computational models and soot sub-models. In this study, the thermophoretic sampling particle diagnostic (TSPD) technique is applied along with data from a previous spectrally resolved line-of-sight light attenuation experiment to determine the soot volume fraction and absorption function. The TSPD technique is applied in a flame stabilized on the Yale burner, and the soot scattering-to-absorption ratio is calculated using the Rayleigh–Debye–Gans theory for fractal aggregates and morphology information from a previous sampling experiment. The soot absorption function is determined as a function of wavelength and found to be in excellent agreement with previous in-flame measurements of the soot absorption function in coflow laminar diffusion flames. Two-dimensional maps of the soot dispersion exponent are calculated and show that the soot absorption function may have a positive or negative exponential wavelength dependence depending on the in-flame location. Finally, the wavelength dependence of the soot absorption function is related to the ratio of soot absorption functions, as would be found using two-excitation-wavelength laser-induced incandescence.

Original languageEnglish (US)
Article number232
JournalApplied Physics B: Lasers and Optics
Volume122
Issue number9
DOIs
StatePublished - Sep 1 2016

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)

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