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Comparison of the Lift-Off Lengths Obtained by Simultaneous OH-LIF and OH∗ Chemiluminescence Imaging in an Optical Heavy-Duty Diesel Engine

Li, Zheming LU ; Yu, Xin; Lequien, Guillaume LU ; Lind, Ted LU ; Jansons, Marcis; Andersson, Öivind LU and Richter, Mattias LU (2015) 12th International Conference on Engines and Vehicles, ICE 2015 In 12th International Conference on Engines and Vehicles, ICE 2015 2015-September.
Abstract

The presence of OH radicals as a marker of the high temperature reaction region usually has been used to determine the lift-off length (LOL) in diesel engines. Both OH Laser Induced Fluorescence (LIF) and OH∗ chemiluminescence diagnostics have been widely used in optical engines for measuring the LOL. OH∗ chemiluminescence is radiation from OH being formed in the exited states (OH∗). As a consequence OH∗ chemiluminescence imaging provides line-of-sight information across the imaged volume. In contrast, OH-LIF provides information on the distribution of radicals present in the energy ground state. The OH-LIF images only show OH distribution in the thin cross-section illuminated by the laser. When both these techniques have been applied... (More)

The presence of OH radicals as a marker of the high temperature reaction region usually has been used to determine the lift-off length (LOL) in diesel engines. Both OH Laser Induced Fluorescence (LIF) and OH∗ chemiluminescence diagnostics have been widely used in optical engines for measuring the LOL. OH∗ chemiluminescence is radiation from OH being formed in the exited states (OH∗). As a consequence OH∗ chemiluminescence imaging provides line-of-sight information across the imaged volume. In contrast, OH-LIF provides information on the distribution of radicals present in the energy ground state. The OH-LIF images only show OH distribution in the thin cross-section illuminated by the laser. When both these techniques have been applied in earlier work, it has often been reported that the chemiluminescence measurements result in shorter lift-off lengths than the LIF approach. In order to investigate this discrepancy this work presents a dedicated comparison of the LOL obtained from these two diagnostic techniques. In diesel engines, the cycle-to-cycle variations in lift-off region are usually significant. To avoid misinterpretations caused by these variations simultaneous measurements are needed. The statistical analysis based on our simultaneous data can conclude that the OH-LIF method yields longer LOL than the OH∗ chemiluminescence method by a smaller sample size and more precisely than non-simultaneous data. This can be partially explained by the 3D geometry and flame axis asymmetry effects. A numerical simulation with OH and OH∗ distribution was performed for the comparison. It shows a great agreement with the experimental results in this study.

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Chapter in Book/Report/Conference proceeding
publication status
published
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in
12th International Conference on Engines and Vehicles, ICE 2015
volume
2015-September
publisher
SAE International
conference name
12th International Conference on Engines and Vehicles, ICE 2015
external identifiers
  • Scopus:84959374568
DOI
10.4271/2015-24-2418
language
English
LU publication?
yes
id
8431f352-0c98-4b0a-ba12-0b936c54ef4c
date added to LUP
2016-09-23 09:01:58
date last changed
2016-09-23 09:01:58
@misc{8431f352-0c98-4b0a-ba12-0b936c54ef4c,
  abstract     = {<p>The presence of OH radicals as a marker of the high temperature reaction region usually has been used to determine the lift-off length (LOL) in diesel engines. Both OH Laser Induced Fluorescence (LIF) and OH∗ chemiluminescence diagnostics have been widely used in optical engines for measuring the LOL. OH∗ chemiluminescence is radiation from OH being formed in the exited states (OH∗). As a consequence OH∗ chemiluminescence imaging provides line-of-sight information across the imaged volume. In contrast, OH-LIF provides information on the distribution of radicals present in the energy ground state. The OH-LIF images only show OH distribution in the thin cross-section illuminated by the laser. When both these techniques have been applied in earlier work, it has often been reported that the chemiluminescence measurements result in shorter lift-off lengths than the LIF approach. In order to investigate this discrepancy this work presents a dedicated comparison of the LOL obtained from these two diagnostic techniques. In diesel engines, the cycle-to-cycle variations in lift-off region are usually significant. To avoid misinterpretations caused by these variations simultaneous measurements are needed. The statistical analysis based on our simultaneous data can conclude that the OH-LIF method yields longer LOL than the OH∗ chemiluminescence method by a smaller sample size and more precisely than non-simultaneous data. This can be partially explained by the 3D geometry and flame axis asymmetry effects. A numerical simulation with OH and OH∗ distribution was performed for the comparison. It shows a great agreement with the experimental results in this study.</p>},
  author       = {Li, Zheming and Yu, Xin and Lequien, Guillaume and Lind, Ted and Jansons, Marcis and Andersson, Öivind and Richter, Mattias},
  language     = {eng},
  month        = {09},
  publisher    = {ARRAY(0x95518c8)},
  series       = {12th International Conference on Engines and Vehicles, ICE 2015},
  title        = {Comparison of the Lift-Off Lengths Obtained by Simultaneous OH-LIF and OH∗ Chemiluminescence Imaging in an Optical Heavy-Duty Diesel Engine},
  url          = {http://dx.doi.org/10.4271/2015-24-2418},
  volume       = {2015-September},
  year         = {2015},
}