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Wavelength dependence of extinction in sooting flat premixed flames in the visible and near-infrared regimes

Simonsson, Johan LU ; Olofsson, Nils-Erik LU ; Török, Sandra LU ; Bengtsson, Per-Erik LU and Bladh, Henrik LU (2015) In Applied Physics B 119(4). p.657-667
Abstract
A diode-laser-based setup was used for extinction measurements at various heights in two flat premixed sooting ethylene/air flames in order to investigate the wavelength dependence of the extinction. Twelve laser wavelengths were used in the interval 405-1064 nm, and with this setup, a sensitivity of similar to 10(-4) was achieved for the extinction. Soot volume fractions inferred from the extinction measurements were always higher in the visible spectral region than in the infrared, an effect associated with additional absorption by large hydrocarbons, such as polycyclic aromatic hydrocarbons. For wavelengths greater than around 700 nm and at high heights above burner (HAB), the extinction shows an inverse dependence with wavelength, in... (More)
A diode-laser-based setup was used for extinction measurements at various heights in two flat premixed sooting ethylene/air flames in order to investigate the wavelength dependence of the extinction. Twelve laser wavelengths were used in the interval 405-1064 nm, and with this setup, a sensitivity of similar to 10(-4) was achieved for the extinction. Soot volume fractions inferred from the extinction measurements were always higher in the visible spectral region than in the infrared, an effect associated with additional absorption by large hydrocarbons, such as polycyclic aromatic hydrocarbons. For wavelengths greater than around 700 nm and at high heights above burner (HAB), the extinction shows an inverse dependence with wavelength, in concurrence with wavelength-independent optical properties of soot. In the same spectral region at lower HAB, the wavelength dependence is observed to be stronger, indicating that the soot optical properties show variation with wavelength. Furthermore, a continuous change in the wavelength dependence of the absorption function E(m) is shown from nascent soot at lower heights to more mature soot at higher heights. The presented results are of importance for soot diagnostics relying on the efficiency of light absorption by soot such as laser-induced incandescence (LII). (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Applied Physics B
volume
119
issue
4
pages
657 - 667
publisher
Springer
external identifiers
  • wos:000354703800007
  • scopus:84929704863
ISSN
0946-2171
DOI
10.1007/s00340-015-6079-z
language
English
LU publication?
yes
id
d0c4c3fe-ee22-4d2e-ac14-da16bf47782f (old id 7422732)
date added to LUP
2015-06-26 11:02:06
date last changed
2017-11-19 03:03:49
@article{d0c4c3fe-ee22-4d2e-ac14-da16bf47782f,
  abstract     = {A diode-laser-based setup was used for extinction measurements at various heights in two flat premixed sooting ethylene/air flames in order to investigate the wavelength dependence of the extinction. Twelve laser wavelengths were used in the interval 405-1064 nm, and with this setup, a sensitivity of similar to 10(-4) was achieved for the extinction. Soot volume fractions inferred from the extinction measurements were always higher in the visible spectral region than in the infrared, an effect associated with additional absorption by large hydrocarbons, such as polycyclic aromatic hydrocarbons. For wavelengths greater than around 700 nm and at high heights above burner (HAB), the extinction shows an inverse dependence with wavelength, in concurrence with wavelength-independent optical properties of soot. In the same spectral region at lower HAB, the wavelength dependence is observed to be stronger, indicating that the soot optical properties show variation with wavelength. Furthermore, a continuous change in the wavelength dependence of the absorption function E(m) is shown from nascent soot at lower heights to more mature soot at higher heights. The presented results are of importance for soot diagnostics relying on the efficiency of light absorption by soot such as laser-induced incandescence (LII).},
  author       = {Simonsson, Johan and Olofsson, Nils-Erik and Török, Sandra and Bengtsson, Per-Erik and Bladh, Henrik},
  issn         = {0946-2171},
  language     = {eng},
  number       = {4},
  pages        = {657--667},
  publisher    = {Springer},
  series       = {Applied Physics B},
  title        = {Wavelength dependence of extinction in sooting flat premixed flames in the visible and near-infrared regimes},
  url          = {http://dx.doi.org/10.1007/s00340-015-6079-z},
  volume       = {119},
  year         = {2015},
}