Flame front visualization in turbulent premixed ethylene/air flames by laser-induced photofragmentation fluorescence
(2024) In Proceedings of the Combustion Institute 40(1-4).- Abstract
The elucidation of premixed ethylene/air combustion mechanisms holds theoretical significance for optimizing engines such as pulse detonation engines and rotating detonation engines. The flame front structure constitutes a vital factor of premixed ethylene/air combustion mechanisms, while the prevailing planar laser-induced fluorescence techniques currently in use fall short of directly visualizing the reaction zone of ethylene flames. Here, we, for the first time, employ the planar laser-induced photofragmentation fluorescence technique to achieve direct visualization of the reaction zone in premixed ethylene/air jet flames over a broad range of equivalence ratios (φ = 0.4–1.8). The application of a 212.8 nm laser for the... (More)
The elucidation of premixed ethylene/air combustion mechanisms holds theoretical significance for optimizing engines such as pulse detonation engines and rotating detonation engines. The flame front structure constitutes a vital factor of premixed ethylene/air combustion mechanisms, while the prevailing planar laser-induced fluorescence techniques currently in use fall short of directly visualizing the reaction zone of ethylene flames. Here, we, for the first time, employ the planar laser-induced photofragmentation fluorescence technique to achieve direct visualization of the reaction zone in premixed ethylene/air jet flames over a broad range of equivalence ratios (φ = 0.4–1.8). The application of a 212.8 nm laser for the photofragmentation of ethylene combustion intermediates results in the generation of abundant C2 Swan bands fluorescence. Through a comparative analysis of experimental and simulation outcomes, it is established that this fluorescence primarily originates from C2* produced after the three-photon photofragmentation of C2H2, which is present in relatively high concentrations in ethylene/air flames, enabling direct visualization of the flame front structure. To enhance the signal-to-noise ratio (SNR), we further adopt a pump-probe approach by introducing a 516.5 nm probe laser to excite the low-energy state C2 produced from the 212.8 nm laser-induced photofragmentation of C2H2. This methodology results in a doubling of the overall imaging SNR.
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- author
- Han, Lei ; Liu, Zihan ; Gao, Qiang LU ; Li, Zhongshan LU and Li, Bo LU
- organization
- publishing date
- 2024-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- C swan bands emission, Flame front visualization, Photofragmentation, Turbulent ethylene/air combustion
- in
- Proceedings of the Combustion Institute
- volume
- 40
- issue
- 1-4
- article number
- 105563
- publisher
- Elsevier
- external identifiers
-
- scopus:85198979391
- ISSN
- 1540-7489
- DOI
- 10.1016/j.proci.2024.105563
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2024 The Combustion Institute
- id
- 1660b3cb-19ca-4c79-be48-942e83dde1ec
- date added to LUP
- 2024-07-29 08:32:41
- date last changed
- 2024-08-12 15:47:12
@article{1660b3cb-19ca-4c79-be48-942e83dde1ec,
abstract = {{<p>The elucidation of premixed ethylene/air combustion mechanisms holds theoretical significance for optimizing engines such as pulse detonation engines and rotating detonation engines. The flame front structure constitutes a vital factor of premixed ethylene/air combustion mechanisms, while the prevailing planar laser-induced fluorescence techniques currently in use fall short of directly visualizing the reaction zone of ethylene flames. Here, we, for the first time, employ the planar laser-induced photofragmentation fluorescence technique to achieve direct visualization of the reaction zone in premixed ethylene/air jet flames over a broad range of equivalence ratios (φ = 0.4–1.8). The application of a 212.8 nm laser for the photofragmentation of ethylene combustion intermediates results in the generation of abundant C<sub>2</sub> Swan bands fluorescence. Through a comparative analysis of experimental and simulation outcomes, it is established that this fluorescence primarily originates from C<sub>2</sub>* produced after the three-photon photofragmentation of C<sub>2</sub>H<sub>2</sub>, which is present in relatively high concentrations in ethylene/air flames, enabling direct visualization of the flame front structure. To enhance the signal-to-noise ratio (SNR), we further adopt a pump-probe approach by introducing a 516.5 nm probe laser to excite the low-energy state C<sub>2</sub> produced from the 212.8 nm laser-induced photofragmentation of C<sub>2</sub>H<sub>2</sub>. This methodology results in a doubling of the overall imaging SNR.</p>}},
author = {{Han, Lei and Liu, Zihan and Gao, Qiang and Li, Zhongshan and Li, Bo}},
issn = {{1540-7489}},
keywords = {{C swan bands emission; Flame front visualization; Photofragmentation; Turbulent ethylene/air combustion}},
language = {{eng}},
number = {{1-4}},
publisher = {{Elsevier}},
series = {{Proceedings of the Combustion Institute}},
title = {{Flame front visualization in turbulent premixed ethylene/air flames by laser-induced photofragmentation fluorescence}},
url = {{http://dx.doi.org/10.1016/j.proci.2024.105563}},
doi = {{10.1016/j.proci.2024.105563}},
volume = {{40}},
year = {{2024}},
}