Dynamics of atomic oxygen production in an NH3/air flame assisted by a nanosecond pulsed plasma discharge
(2024) In Proceedings of the Combustion Institute 40(1-4).- Abstract
- Atomic oxygen (O) is vital in plasma-assisted combustion, but its quantitative measurement is challenging and therefore rarely reported. This work performs femtosecond two-photon-absorption laser-induced fluorescence (fs-TALIF) imaging to quantify the dynamics of atomic oxygen production by a single nanosecond (ns) pulsed plasma discharge in an ammonia/air flame for the first time. First of all, the plasma kinetic enhancement is quantified by the plasma-produced O with a molar fraction of up to 2.8 × 10−3, which is at least one order higher than that in the flame without plasma. Then, the spatial distribution of O demonstrates significant differences between the unburnt and burnt zones, revealing the distinct mechanisms of O production in... (More)
- Atomic oxygen (O) is vital in plasma-assisted combustion, but its quantitative measurement is challenging and therefore rarely reported. This work performs femtosecond two-photon-absorption laser-induced fluorescence (fs-TALIF) imaging to quantify the dynamics of atomic oxygen production by a single nanosecond (ns) pulsed plasma discharge in an ammonia/air flame for the first time. First of all, the plasma kinetic enhancement is quantified by the plasma-produced O with a molar fraction of up to 2.8 × 10−3, which is at least one order higher than that in the flame without plasma. Then, the spatial distribution of O demonstrates significant differences between the unburnt and burnt zones, revealing the distinct mechanisms of O production in unburnt and burnt NH3/air mixtures. Specifically, a new O region is formed in the burnt zone of the lean flame, which is probably mainly caused by the pathway of NO dissociation into O by the ns plasma. Furthermore, the temporal dynamics of O in different zones are discussed in-depth. In the unburnt zone, from the continuous increment of O after hundreds of ns following the ns discharge initiation, it can be seen that the relaxation of the excited nitrogen plays an equally important role in O production as the direct electron impact. Subsequently, O atoms in the unburnt zone exhibit an exponential decay, which is attributed to the formation of O3 from O. Whereas, in the burnt zone, a bi-exponential decay of O is found for the first time. Such decay mainly results from the reaction between O and H2O, which importantly, is a reaction to form OH radicals. The transition between decays is due to the formation of the O region in the unburnt zone and the dominance of the combustion kinetics in the post-plasma stage. © 2024 The Author(s) (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/faed1916-8a5b-4183-adb1-cb389e35016c
- author
- Sun, Jinguo
LU
; Ravelid, Jonas LU ; Bao, Yupan LU ; Nilsson, Sebastian LU ; Konnov, Alexander A LU and Ehn, Andreas LU
- organization
- publishing date
- 2024
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Proceedings of the Combustion Institute
- volume
- 40
- issue
- 1-4
- article number
- 105477
- pages
- 7 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:85197507041
- ISSN
- 1540-7489
- DOI
- 10.1016/j.proci.2024.105477
- language
- English
- LU publication?
- yes
- id
- faed1916-8a5b-4183-adb1-cb389e35016c
- date added to LUP
- 2024-07-30 10:28:46
- date last changed
- 2024-08-13 08:35:26
@article{faed1916-8a5b-4183-adb1-cb389e35016c, abstract = {{Atomic oxygen (O) is vital in plasma-assisted combustion, but its quantitative measurement is challenging and therefore rarely reported. This work performs femtosecond two-photon-absorption laser-induced fluorescence (fs-TALIF) imaging to quantify the dynamics of atomic oxygen production by a single nanosecond (ns) pulsed plasma discharge in an ammonia/air flame for the first time. First of all, the plasma kinetic enhancement is quantified by the plasma-produced O with a molar fraction of up to 2.8 × 10−3, which is at least one order higher than that in the flame without plasma. Then, the spatial distribution of O demonstrates significant differences between the unburnt and burnt zones, revealing the distinct mechanisms of O production in unburnt and burnt NH3/air mixtures. Specifically, a new O region is formed in the burnt zone of the lean flame, which is probably mainly caused by the pathway of NO dissociation into O by the ns plasma. Furthermore, the temporal dynamics of O in different zones are discussed in-depth. In the unburnt zone, from the continuous increment of O after hundreds of ns following the ns discharge initiation, it can be seen that the relaxation of the excited nitrogen plays an equally important role in O production as the direct electron impact. Subsequently, O atoms in the unburnt zone exhibit an exponential decay, which is attributed to the formation of O3 from O. Whereas, in the burnt zone, a bi-exponential decay of O is found for the first time. Such decay mainly results from the reaction between O and H2O, which importantly, is a reaction to form OH radicals. The transition between decays is due to the formation of the O region in the unburnt zone and the dominance of the combustion kinetics in the post-plasma stage. © 2024 The Author(s)}}, author = {{Sun, Jinguo and Ravelid, Jonas and Bao, Yupan and Nilsson, Sebastian and Konnov, Alexander A and Ehn, Andreas}}, issn = {{1540-7489}}, language = {{eng}}, number = {{1-4}}, publisher = {{Elsevier}}, series = {{Proceedings of the Combustion Institute}}, title = {{Dynamics of atomic oxygen production in an NH3/air flame assisted by a nanosecond pulsed plasma discharge}}, url = {{http://dx.doi.org/10.1016/j.proci.2024.105477}}, doi = {{10.1016/j.proci.2024.105477}}, volume = {{40}}, year = {{2024}}, }