Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)

T. Ombrello; Sang Hee Won; Yiguang Ju; S. Williams

doi:10.1016/j.combustflame.2010.02.004

Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O₂(a¹Δ_g)

T. Ombrello, Sang Hee Won, Yiguang Ju, S. Williams

Research output: Contribution to journal › Article › peer-review

226 Scopus citations

Abstract

The isolated effect of O₂(a¹Δ_g) on the propagation of C₂H₄ lifted flames was studied at reduced pressures (3.61kPa and 6.73kPa). The O₂(a¹Δ_g) was produced in a microwave discharge plasma and was isolated from O and O₃ by NO addition to the plasma afterglow in a flow residence time on the order of 1s. The concentrations of O₂(a¹Δ_g) and O₃ were measured quantitatively through absorption by sensitive off-axis integrated-cavity-output spectroscopy and one-pass line-of-sight absorption, respectively. Under these conditions, it was found that O₂(a¹Δ_g) enhanced the propagation speed of C₂H₄ lifted flames. Comparison with the results of enhancement by O₃ found in part I of this investigation provided an estimation of 2-3% of flame speed enhancement for 5500ppm of O₂(a¹Δ_g) addition from the plasma. Numerical simulation results using the current kinetic model of O₂(a¹Δ_g) over-predicts the flame propagation enhancement found in the experiments. However, the inclusion of collisional quenching rate estimations of O₂(a¹Δ_g) by C₂H₄ mitigated the over-prediction. The present isolated experimental results of the enhancement of a hydrocarbon fueled flame by O₂(a¹Δ_g), along with kinetic modeling results suggest that further studies of C_nH_m+O₂(a¹Δ_g) collisional and reactive quenching are required in order to correctly predict combustion enhancement by O₂(a¹Δ_g). The present experimental results will have a direct impact on the development of elementary reaction rates with O₂(a¹Δ_g) at flame conditions to establish detailed plasma-flame kinetic mechanisms.

Original language	English (US)
Pages (from-to)	1916-1928
Number of pages	13
Journal	Combustion and Flame
Volume	157
Issue number	10
DOIs	https://doi.org/10.1016/j.combustflame.2010.02.004
State	Published - Oct 2010

All Science Journal Classification (ASJC) codes

General Chemistry
General Chemical Engineering
Fuel Technology
Energy Engineering and Power Technology
General Physics and Astronomy

Keywords

Flame propagation enhancement
Flame speed enhancement
Lifted flame
Plasma-assisted combustion
Singlet delta oxygen
Tribrachial flame

Access to Document

10.1016/j.combustflame.2010.02.004

Cite this

@article{65f742c8edef4e5ca2442af2b7a058d9,

title = "Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)",

abstract = "The isolated effect of O2(a1Δg) on the propagation of C2H4 lifted flames was studied at reduced pressures (3.61kPa and 6.73kPa). The O2(a1Δg) was produced in a microwave discharge plasma and was isolated from O and O3 by NO addition to the plasma afterglow in a flow residence time on the order of 1s. The concentrations of O2(a1Δg) and O3 were measured quantitatively through absorption by sensitive off-axis integrated-cavity-output spectroscopy and one-pass line-of-sight absorption, respectively. Under these conditions, it was found that O2(a1Δg) enhanced the propagation speed of C2H4 lifted flames. Comparison with the results of enhancement by O3 found in part I of this investigation provided an estimation of 2-3% of flame speed enhancement for 5500ppm of O2(a1Δg) addition from the plasma. Numerical simulation results using the current kinetic model of O2(a1Δg) over-predicts the flame propagation enhancement found in the experiments. However, the inclusion of collisional quenching rate estimations of O2(a1Δg) by C2H4 mitigated the over-prediction. The present isolated experimental results of the enhancement of a hydrocarbon fueled flame by O2(a1Δg), along with kinetic modeling results suggest that further studies of CnHm+O2(a1Δg) collisional and reactive quenching are required in order to correctly predict combustion enhancement by O2(a1Δg). The present experimental results will have a direct impact on the development of elementary reaction rates with O2(a1Δg) at flame conditions to establish detailed plasma-flame kinetic mechanisms.",

keywords = "Flame propagation enhancement, Flame speed enhancement, Lifted flame, Plasma-assisted combustion, Singlet delta oxygen, Tribrachial flame",

author = "T. Ombrello and Won, {Sang Hee} and Yiguang Ju and S. Williams",

note = "Funding Information: This work was supported by the Air Force Office of Scientific Research (Award Number FA9550-07-1-0136) under program manager Dr. Julian Tishkoff and Dr. Michael Berman, as well as the AFOSR MURI research grant on plasma-assisted combustion. Part of the research was performed while the corresponding author held a National Research Council Research Associateship Award at the United States Air Force Research Laboratory, Wright-Patterson Air Force Base. The authors wish to thank Dr. Campbell Carter for insightful discussions and Mr. Wenting Sun for his help with some of the experiments. ",

year = "2010",

month = oct,

doi = "10.1016/j.combustflame.2010.02.004",

language = "English (US)",

volume = "157",

pages = "1916--1928",

journal = "Combustion and Flame",

issn = "0010-2180",

publisher = "Elsevier Inc.",

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}

TY - JOUR

T1 - Flame propagation enhancement by plasma excitation of oxygen. Part II

T2 - Effects of O2(a1Δg)

AU - Ombrello, T.

AU - Won, Sang Hee

AU - Ju, Yiguang

AU - Williams, S.

N1 - Funding Information: This work was supported by the Air Force Office of Scientific Research (Award Number FA9550-07-1-0136) under program manager Dr. Julian Tishkoff and Dr. Michael Berman, as well as the AFOSR MURI research grant on plasma-assisted combustion. Part of the research was performed while the corresponding author held a National Research Council Research Associateship Award at the United States Air Force Research Laboratory, Wright-Patterson Air Force Base. The authors wish to thank Dr. Campbell Carter for insightful discussions and Mr. Wenting Sun for his help with some of the experiments.

PY - 2010/10

Y1 - 2010/10

N2 - The isolated effect of O2(a1Δg) on the propagation of C2H4 lifted flames was studied at reduced pressures (3.61kPa and 6.73kPa). The O2(a1Δg) was produced in a microwave discharge plasma and was isolated from O and O3 by NO addition to the plasma afterglow in a flow residence time on the order of 1s. The concentrations of O2(a1Δg) and O3 were measured quantitatively through absorption by sensitive off-axis integrated-cavity-output spectroscopy and one-pass line-of-sight absorption, respectively. Under these conditions, it was found that O2(a1Δg) enhanced the propagation speed of C2H4 lifted flames. Comparison with the results of enhancement by O3 found in part I of this investigation provided an estimation of 2-3% of flame speed enhancement for 5500ppm of O2(a1Δg) addition from the plasma. Numerical simulation results using the current kinetic model of O2(a1Δg) over-predicts the flame propagation enhancement found in the experiments. However, the inclusion of collisional quenching rate estimations of O2(a1Δg) by C2H4 mitigated the over-prediction. The present isolated experimental results of the enhancement of a hydrocarbon fueled flame by O2(a1Δg), along with kinetic modeling results suggest that further studies of CnHm+O2(a1Δg) collisional and reactive quenching are required in order to correctly predict combustion enhancement by O2(a1Δg). The present experimental results will have a direct impact on the development of elementary reaction rates with O2(a1Δg) at flame conditions to establish detailed plasma-flame kinetic mechanisms.

AB - The isolated effect of O2(a1Δg) on the propagation of C2H4 lifted flames was studied at reduced pressures (3.61kPa and 6.73kPa). The O2(a1Δg) was produced in a microwave discharge plasma and was isolated from O and O3 by NO addition to the plasma afterglow in a flow residence time on the order of 1s. The concentrations of O2(a1Δg) and O3 were measured quantitatively through absorption by sensitive off-axis integrated-cavity-output spectroscopy and one-pass line-of-sight absorption, respectively. Under these conditions, it was found that O2(a1Δg) enhanced the propagation speed of C2H4 lifted flames. Comparison with the results of enhancement by O3 found in part I of this investigation provided an estimation of 2-3% of flame speed enhancement for 5500ppm of O2(a1Δg) addition from the plasma. Numerical simulation results using the current kinetic model of O2(a1Δg) over-predicts the flame propagation enhancement found in the experiments. However, the inclusion of collisional quenching rate estimations of O2(a1Δg) by C2H4 mitigated the over-prediction. The present isolated experimental results of the enhancement of a hydrocarbon fueled flame by O2(a1Δg), along with kinetic modeling results suggest that further studies of CnHm+O2(a1Δg) collisional and reactive quenching are required in order to correctly predict combustion enhancement by O2(a1Δg). The present experimental results will have a direct impact on the development of elementary reaction rates with O2(a1Δg) at flame conditions to establish detailed plasma-flame kinetic mechanisms.

KW - Flame propagation enhancement

KW - Flame speed enhancement

KW - Lifted flame

KW - Plasma-assisted combustion

KW - Singlet delta oxygen

KW - Tribrachial flame

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