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Title: Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

Abstract

A hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H 2/air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygen measurements in near-adiabatic H 2/air flames stabilized on the Hencken burner for equivalence ratios of φ = 0.20–1.20. Thermometry is demonstrated in hydrocarbon/air products for φ = 0.75–3.14 in premixed C 2H 4/air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H 2/air flames, and by comparison with nanosecond CARS measurements for the C 2H 4/air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both themore » temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1–2% precision in temperature and O 2/N 2 ratio are identified. Our results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide range of flame conditions spanning lean H 2/air combustion to fuel-rich sooting hydrocarbon flames.« less

Authors:
 [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Science (NA-113)
OSTI Identifier:
1183118
Alternate Identifier(s):
OSTI ID: 1246725
Report Number(s):
SAND2014-17275J
Journal ID: ISSN 0010-2180; 537187
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Combustion and Flame
Additional Journal Information:
Journal Volume: 162; Journal ID: ISSN 0010-2180
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; laser diagnostics; femtosecond CARS; flat flames; temperature; oxygen

Citation Formats

Kearney, Sean Patrick. Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames. United States: N. p., 2014. Web. doi:10.1016/j.combustflame.2014.11.036.
Kearney, Sean Patrick. Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames. United States. doi:10.1016/j.combustflame.2014.11.036.
Kearney, Sean Patrick. Wed . "Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames". United States. doi:10.1016/j.combustflame.2014.11.036. https://www.osti.gov/servlets/purl/1183118.
@article{osti_1183118,
title = {Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames},
author = {Kearney, Sean Patrick},
abstractNote = {A hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H2/air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygen measurements in near-adiabatic H2/air flames stabilized on the Hencken burner for equivalence ratios of φ = 0.20–1.20. Thermometry is demonstrated in hydrocarbon/air products for φ = 0.75–3.14 in premixed C2H4/air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H2/air flames, and by comparison with nanosecond CARS measurements for the C2H4/air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both the temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1–2% precision in temperature and O2/N2 ratio are identified. Our results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide range of flame conditions spanning lean H2/air combustion to fuel-rich sooting hydrocarbon flames.},
doi = {10.1016/j.combustflame.2014.11.036},
journal = {Combustion and Flame},
number = ,
volume = 162,
place = {United States},
year = {Wed Dec 31 00:00:00 EST 2014},
month = {Wed Dec 31 00:00:00 EST 2014}
}

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