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Photofragmentation laser-induced fluorescence imaging in premixed flames

Johansson, Olof LU ; Bood, Joakim LU ; Li, Bo LU ; Ehn, Andreas LU ; Li, Zhongshan LU ; Sun, Zhiwei LU ; Jonsson, Malin LU ; Konnov, Alexander LU and Aldén, Marcus LU (2011) In Combustion and Flame 158(10). p.1908-1919
Abstract
Two-dimensional measurements of primarily hydroperoxyl radicals (HO2) are, for the first time, demonstrated in flames. The measurements are performed in different Bunsen-type premixed flames (H-2/O-2. CH4/O-2, and CH4/air) using photofragmentation laser-induced fluorescence (PF-LIF). Photofragmentation is done by laser radiation at 266 nm, and the generated OH photofragments are probed through fluorescence induced by a laser tuned to the Q(1)(5) transition at 282.75 nm. The signal due to naturally occurring OH radicals, recorded by having the photolysis laser blocked, is subtracted, providing an image that reflects the concentration of OH fragments generated by photolysis, and hence the presence of primarily HO2, but also smaller... (More)
Two-dimensional measurements of primarily hydroperoxyl radicals (HO2) are, for the first time, demonstrated in flames. The measurements are performed in different Bunsen-type premixed flames (H-2/O-2. CH4/O-2, and CH4/air) using photofragmentation laser-induced fluorescence (PF-LIF). Photofragmentation is done by laser radiation at 266 nm, and the generated OH photofragments are probed through fluorescence induced by a laser tuned to the Q(1)(5) transition at 282.75 nm. The signal due to naturally occurring OH radicals, recorded by having the photolysis laser blocked, is subtracted, providing an image that reflects the concentration of OH fragments generated by photolysis, and hence the presence of primarily HO2, but also smaller contributions from H2O2 and, for the methane flames, CH3O2. For the methane flames the measured radial profiles of OH photofragments and natural OH agree well with corresponding profiles calculated for laminar, one-dimensional, premixed flames using CHEMKIN-II with the Konnov detailed C/H/N/O reaction mechanism. An interfering signal contribution is observed in the product zone of the methane flames. It is concluded that the major source for the interference is most likely hot CO2, from which 0 atoms are produced by photolysis, and OH is rapidly formed as the O atoms react with H2O and H-2. This conclusion is supported by the fact that the interference is absent for the hydrogen flame, but appears when CO2 is seeded into the flame. Another strong indication is that the Konnov mechanism predicts a similar buildup of OH after photolysis. (C) 2011 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
Combustion diagnostics, Photofragmentation, Laser-induced fluorescence, Hydrogen peroxide, Hydroperoxyl radical, Methyl peroxy radical
in
Combustion and Flame
volume
158
issue
10
pages
1908 - 1919
publisher
Elsevier
external identifiers
  • wos:000294525200007
  • scopus:80052385274
ISSN
0010-2180
DOI
10.1016/j.combustflame.2011.02.021
language
English
LU publication?
yes
id
47562296-0958-4fbf-8606-d4f3912a1848 (old id 2160586)
date added to LUP
2011-09-21 16:20:36
date last changed
2017-09-17 06:51:24
@article{47562296-0958-4fbf-8606-d4f3912a1848,
  abstract     = {Two-dimensional measurements of primarily hydroperoxyl radicals (HO2) are, for the first time, demonstrated in flames. The measurements are performed in different Bunsen-type premixed flames (H-2/O-2. CH4/O-2, and CH4/air) using photofragmentation laser-induced fluorescence (PF-LIF). Photofragmentation is done by laser radiation at 266 nm, and the generated OH photofragments are probed through fluorescence induced by a laser tuned to the Q(1)(5) transition at 282.75 nm. The signal due to naturally occurring OH radicals, recorded by having the photolysis laser blocked, is subtracted, providing an image that reflects the concentration of OH fragments generated by photolysis, and hence the presence of primarily HO2, but also smaller contributions from H2O2 and, for the methane flames, CH3O2. For the methane flames the measured radial profiles of OH photofragments and natural OH agree well with corresponding profiles calculated for laminar, one-dimensional, premixed flames using CHEMKIN-II with the Konnov detailed C/H/N/O reaction mechanism. An interfering signal contribution is observed in the product zone of the methane flames. It is concluded that the major source for the interference is most likely hot CO2, from which 0 atoms are produced by photolysis, and OH is rapidly formed as the O atoms react with H2O and H-2. This conclusion is supported by the fact that the interference is absent for the hydrogen flame, but appears when CO2 is seeded into the flame. Another strong indication is that the Konnov mechanism predicts a similar buildup of OH after photolysis. (C) 2011 The Combustion Institute. Published by Elsevier Inc. All rights reserved.},
  author       = {Johansson, Olof and Bood, Joakim and Li, Bo and Ehn, Andreas and Li, Zhongshan and Sun, Zhiwei and Jonsson, Malin and Konnov, Alexander and Aldén, Marcus},
  issn         = {0010-2180},
  keyword      = {Combustion diagnostics,Photofragmentation,Laser-induced fluorescence,Hydrogen peroxide,Hydroperoxyl radical,Methyl peroxy radical},
  language     = {eng},
  number       = {10},
  pages        = {1908--1919},
  publisher    = {Elsevier},
  series       = {Combustion and Flame},
  title        = {Photofragmentation laser-induced fluorescence imaging in premixed flames},
  url          = {http://dx.doi.org/10.1016/j.combustflame.2011.02.021},
  volume       = {158},
  year         = {2011},
}