| Autor: |
Courtney TL; Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA., Bohlin A; Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA., Patterson BD; Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA., Kliewer CJ; Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA. |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of chemical physics [J Chem Phys] 2017 Jun 14; Vol. 146 (22), pp. 224202. |
| DOI: |
10.1063/1.4984083 |
| Abstrakt: |
Coherent anti-Stokes Raman spectroscopy (CARS) is a sensitive technique for probing highly luminous flames in combustion applications to determine temperatures and species concentrations. CARS thermometry has been demonstrated for the vibrational Q-branch and pure-rotational S-branch of several small molecules. Practical advantages of pure-rotational CARS, such as multi-species detection, reduction of coherent line mixing and collisional narrowing even at high pressures, and the potential for more precise thermometry, have motivated experimental and theoretical advances in S-branch CARS of nitrogen (N 2 ), for example, which is a dominant species in air-fed combustion processes. Although hydrogen (H 2 ) is of interest given its prevalence as a reactant and product in many gas-phase reactions, laser bandwidth limitations have precluded the extension of CARS thermometry to the H 2 S-branch. We demonstrate H 2 thermometry using hybrid femtosecond/picosecond pure-rotational CARS, in which a broadband pump/Stokes pulse enables simultaneous excitation of the set of H 2 S-branch transitions populated at flame temperatures over the spectral region of 0-2200 cm -1 . We present a pure-rotational H 2 CARS spectral model for data fitting and compare extracted temperatures to those from simultaneously collected N 2 spectra in two systems of study: a heated flow and a diffusion flame on a Wolfhard-Parker slot burner. From 300 to 650 K in the heated flow, the H 2 and N 2 CARS extracted temperatures are, on average, within 2% of the set temperature. For flame measurements, the fitted H 2 and N 2 temperatures are, on average, within 5% of each other from 300 to 1600 K. Our results confirm the viability of pure-rotational H 2 CARS thermometry for probing combustion reactions. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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