Development of two-beam femtosecond/picosecond one-dimensional rotational coherent anti-Stokes Raman spectroscopy: Time-resolved probing of flame wall interactions

Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman spectroscopy (CARS) is developed utilizing a two-beam phase-matching approach for one-dimensional (1D) measurements demonstrated in an impinging jet burner to probe time-resolved head on quenching (HOQ) of a methane/air premixed fla...

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Bibliographic Details
Published in:Proceedings of the Combustion Institute 2015-01, Vol.35 (3), p.3723-3730
Main Authors: Bohlin, Alexis, Mann, Markus, Patterson, Brian D., Dreizler, Andreas, Kliewer, Christopher J.
Format: Article
Language:English
Subjects:
Coherence
Combustion
Femtosecond
Quenching
Raman scattering
Raman spectroscopy
Rotational
Spectra
Temperature gradient
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Summary:Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman spectroscopy (CARS) is developed utilizing a two-beam phase-matching approach for one-dimensional (1D) measurements demonstrated in an impinging jet burner to probe time-resolved head on quenching (HOQ) of a methane/air premixed flame at Phi =1.0 and Reynolds number=5000. Single-laser-shot 1D temperature profiles are obtained over a distance of at least 4mm by fitting the pure-rotational N2 CARS spectra to a spectral library calculated from a time-domain CARS code. An imaging resolution of 61 mu m is obtained in the 1D-CARS measurements. The acquisition of single-shot 1D CARS measurements, as opposed to traditional point-wise CARS techniques, enables new spatially correlated conditional statistics to be determined, such as the position, magnitude, and fluctuations of the instantaneous temperature gradient. The temperature gradient increases as the flame approaches the metal surface, and decreases during quenching. The standard deviation of the temperature gradient follows the same trend as the temperature gradient, increasing as the flame front approaches the surface, and decreasing after quenching.
ISSN:1540-7489
1873-2704
DOI:10.1016/j.proci.2014.05.124