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Probing the smallest soot particles in low-sooting premixed flames using laser-induced incandescence

Bladh, Henrik LU ; Olofsson, Nils-Erik LU ; Mouton, Thomas; Simonsson, Johan LU ; Mercier, Xavier; Faccinetto, Alessandro; Bengtsson, Per-Erik LU and Desgroux, Pascale (2015) In Proceedings of the Combustion Institute 35. p.1843-1850
Abstract
In this work we investigate nascent soot particles by analyzing laser-induced incandescence (LII) signals obtained in low-sooting premixed flames. The analysis covers two data sets obtained in separate experimental campaigns. The first data set was obtained in a previous work (Mouton et al., 2013) in methane/oxygen/nitrogen flames (equivalence ratio range 1.95 < Phi < 2.32) at 26.7 kPa, whereas the second was performed in atmospheric ethylene/air flames (1.77 < Phi < 2.00). Both studies show similar trends, i.e. a gradual change of the fluence curves (evolution of the LII signal as function of the laser fluence) from the well-known S-shaped curve for mature soot found at high heights above the burner (HAB) and high equivalence... (More)
In this work we investigate nascent soot particles by analyzing laser-induced incandescence (LII) signals obtained in low-sooting premixed flames. The analysis covers two data sets obtained in separate experimental campaigns. The first data set was obtained in a previous work (Mouton et al., 2013) in methane/oxygen/nitrogen flames (equivalence ratio range 1.95 < Phi < 2.32) at 26.7 kPa, whereas the second was performed in atmospheric ethylene/air flames (1.77 < Phi < 2.00). Both studies show similar trends, i.e. a gradual change of the fluence curves (evolution of the LII signal as function of the laser fluence) from the well-known S-shaped curve for mature soot found at high heights above the burner (HAB) and high equivalence ratio, to a nearly linear behavior for nascent soot found at low HAB and reduced equivalence ratio. With this change comes a decrease in the LII decay time (and hence inferred particle size). Also, this decay time appears to be almost constant with HAB in flames having the lowest equivalence ratio at which the incandescence signal could be detected. In these flames, so-called nucleation flames, the stability of the particle size with HAB suggests that recently nucleated particles have undergone marginal surface growth and coagulation. Existence of such nucleation flames is of great interest for improving the theoretical description of the nucleation step. Experimental results are analyzed by using a theoretical model for LII to determine the particle size evolution throughout the flame at various experimental conditions. We highlight the size difference from nascent soot particles up to mature soot, giving insight into the particle nucleation and the surface growth processes as a function of reaction time and flame conditions. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Laser-induced incandescence, Premixed flames, Nascent soot particles, Nucleation, Sooting flames
in
Proceedings of the Combustion Institute
volume
35
pages
1843 - 1850
publisher
Elsevier
external identifiers
  • wos:000348048800081
  • scopus:84964290971
ISSN
1540-7489
DOI
10.1016/j.proci.2014.06.001
language
English
LU publication?
yes
id
ff390554-a736-4b43-9828-c7624683920f (old id 5204255)
date added to LUP
2015-03-25 14:30:13
date last changed
2017-10-22 03:04:50
@article{ff390554-a736-4b43-9828-c7624683920f,
  abstract     = {In this work we investigate nascent soot particles by analyzing laser-induced incandescence (LII) signals obtained in low-sooting premixed flames. The analysis covers two data sets obtained in separate experimental campaigns. The first data set was obtained in a previous work (Mouton et al., 2013) in methane/oxygen/nitrogen flames (equivalence ratio range 1.95 &lt; Phi &lt; 2.32) at 26.7 kPa, whereas the second was performed in atmospheric ethylene/air flames (1.77 &lt; Phi &lt; 2.00). Both studies show similar trends, i.e. a gradual change of the fluence curves (evolution of the LII signal as function of the laser fluence) from the well-known S-shaped curve for mature soot found at high heights above the burner (HAB) and high equivalence ratio, to a nearly linear behavior for nascent soot found at low HAB and reduced equivalence ratio. With this change comes a decrease in the LII decay time (and hence inferred particle size). Also, this decay time appears to be almost constant with HAB in flames having the lowest equivalence ratio at which the incandescence signal could be detected. In these flames, so-called nucleation flames, the stability of the particle size with HAB suggests that recently nucleated particles have undergone marginal surface growth and coagulation. Existence of such nucleation flames is of great interest for improving the theoretical description of the nucleation step. Experimental results are analyzed by using a theoretical model for LII to determine the particle size evolution throughout the flame at various experimental conditions. We highlight the size difference from nascent soot particles up to mature soot, giving insight into the particle nucleation and the surface growth processes as a function of reaction time and flame conditions. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.},
  author       = {Bladh, Henrik and Olofsson, Nils-Erik and Mouton, Thomas and Simonsson, Johan and Mercier, Xavier and Faccinetto, Alessandro and Bengtsson, Per-Erik and Desgroux, Pascale},
  issn         = {1540-7489},
  keyword      = {Laser-induced incandescence,Premixed flames,Nascent soot particles,Nucleation,Sooting flames},
  language     = {eng},
  pages        = {1843--1850},
  publisher    = {Elsevier},
  series       = {Proceedings of the Combustion Institute},
  title        = {Probing the smallest soot particles in low-sooting premixed flames using laser-induced incandescence},
  url          = {http://dx.doi.org/10.1016/j.proci.2014.06.001},
  volume       = {35},
  year         = {2015},
}