Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Two-dimensional laser-induced incandescence for soot volume fraction measurements : issues in quantification due to laser beam focusing

Mannazhi, Manu LU and Bengtsson, Per Erik LU orcid (2020) In Applied Physics B: Lasers and Optics 126(12).
Abstract

Two-dimensional laser-induced incandescence (LII) measurements usually involve the use of a cylindrical lens to illuminate the planar region of interest. This creates a varying laser fluence and sheet width in the imaged flame region which could lead to large uncertainties in the quantification of the 2D LII signals into soot volume fraction distributions. To investigate these effects, 2D LII measurements using a wide range of laser pulse energies were performed on a premixed flat ethylene–air flame while employing a cylindrical lens to focus the laser sheet. Using shorter focal length of the focusing lens resulted in larger variation of the LII signal profiles across the flame. A heat – and – mass – transfer - based LII model was also... (More)

Two-dimensional laser-induced incandescence (LII) measurements usually involve the use of a cylindrical lens to illuminate the planar region of interest. This creates a varying laser fluence and sheet width in the imaged flame region which could lead to large uncertainties in the quantification of the 2D LII signals into soot volume fraction distributions. To investigate these effects, 2D LII measurements using a wide range of laser pulse energies were performed on a premixed flat ethylene–air flame while employing a cylindrical lens to focus the laser sheet. Using shorter focal length of the focusing lens resulted in larger variation of the LII signal profiles across the flame. A heat – and – mass – transfer - based LII model was also used to simulate the measurements and good agreement was found. The ratio between focal length (FL) and image length (IL) was introduced as a useful parameter for estimating the bias in estimated soot volume fractions across the flame. The general recommendation is to maximize this FL/IL ratio in an experiment, which in practice means the use of a long focal length lens. Furthermore, the best choices of laser fluence and detection gate width are discussed based on results from these simulations.

(Less)
Please use this url to cite or link to this publication:
author
and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Applied Physics B: Lasers and Optics
volume
126
issue
12
article number
194
publisher
Springer
external identifiers
  • scopus:85095977778
ISSN
0946-2171
DOI
10.1007/s00340-020-07547-9
language
English
LU publication?
yes
id
1e123156-66b4-485d-9ca5-d115dcdfeba0
date added to LUP
2020-11-23 14:37:38
date last changed
2022-04-19 02:19:23
@article{1e123156-66b4-485d-9ca5-d115dcdfeba0,
  abstract     = {{<p>Two-dimensional laser-induced incandescence (LII) measurements usually involve the use of a cylindrical lens to illuminate the planar region of interest. This creates a varying laser fluence and sheet width in the imaged flame region which could lead to large uncertainties in the quantification of the 2D LII signals into soot volume fraction distributions. To investigate these effects, 2D LII measurements using a wide range of laser pulse energies were performed on a premixed flat ethylene–air flame while employing a cylindrical lens to focus the laser sheet. Using shorter focal length of the focusing lens resulted in larger variation of the LII signal profiles across the flame. A heat – and – mass – transfer - based LII model was also used to simulate the measurements and good agreement was found. The ratio between focal length (FL) and image length (IL) was introduced as a useful parameter for estimating the bias in estimated soot volume fractions across the flame. The general recommendation is to maximize this FL/IL ratio in an experiment, which in practice means the use of a long focal length lens. Furthermore, the best choices of laser fluence and detection gate width are discussed based on results from these simulations.</p>}},
  author       = {{Mannazhi, Manu and Bengtsson, Per Erik}},
  issn         = {{0946-2171}},
  language     = {{eng}},
  number       = {{12}},
  publisher    = {{Springer}},
  series       = {{Applied Physics B: Lasers and Optics}},
  title        = {{Two-dimensional laser-induced incandescence for soot volume fraction measurements : issues in quantification due to laser beam focusing}},
  url          = {{http://dx.doi.org/10.1007/s00340-020-07547-9}},
  doi          = {{10.1007/s00340-020-07547-9}},
  volume       = {{126}},
  year         = {{2020}},
}