Development of improved PLIF CH detection using an Alexandrite laser for single-shot investigation of turbulent and lean flames

Z. S. Li, J. Kiefer, J. Zetterberg, M. Linvin, A. Leipertz, X. S. Bai, M. Alden

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

We report on the development of planar laser-induced fluorescence (PLIF) for CH imaging with improved detection sensitivity for single-shot investigations of turbulent, lean, premixed flames. A ring-cavity, pulsed Alexandrite laser was frequency-doubled to excite the lines in the R-branch band-head of the B X (0,0) band and broadband fluorescence from the B-X (0, 1), A-X (1, 1) and (0,0) bands, overlapping in the spectral range around 431 nm, was collected. The employed Alexandrite laser, which is characterized by its long pulse duration (150 ns), gives a tunable laser beam around 775 rim with a pulse energy for the second harmonic at the CH absorption wavelength of about 70 mJ. Moreover, the laser has the possibility to be operated in narrow bandwidth (100 MHz) or broad bandwidth (8 cm(-1)). An introductory high resolution excitation scan over the R-branch band-head was performed and, in addition, saturated excitation with the broadband option of the laser was investigated. By simultaneous excitation of several rotational transitions and to bring these transitions close to saturation, high signal-to-noise ratios were reached over a wide range of equivalence ratios. A sharp and thin CH layer was observed in single-shot PLIF images from laminar premixed methane/air flames from Phi = 0.6 to Phi = 1.5. Finally, the impact of the developed CH PLIF technique is demonstrated in a highly turbulent, lean, partially premixed methane/air flame established on a co-axial jet flame burner. (c) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
Original languageEnglish
Pages (from-to)727-735
Number of pages9
JournalProceedings of the Combustion Institute
Volume31
Issue number1
Early online date30 Aug 2006
DOIs
Publication statusPublished - Jan 2007

Keywords

  • planar laser-induced fluorescence
  • CH radical
  • lean premixed methane/air flame
  • turbulent combustion
  • laser combustion diagnostics

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