Strategy for single-shot CH3 imaging in premixed methane/air flames using photofragmentation laser-induced fluorescence

Bo Li, Dayuan Zhang, Mingfa Yao, Zhongshan Li

Research output: Contribution to journalArticlepeer-review

Abstract

Single-shot imaging of methyl radical (CH3) in premixed methane/air flames is demonstrated using photofragmentation laser-induced fluorescence (PF-LIF) technique. A pump-probe strategy was adopted with the pump laser at 212.8 nm photolyzing CH3, and with the probe laser at 426.8 nm detecting the photolyzed CH (X 2Π) fragments. Spatially resolved spectrograph of the PF-LIF signal from a stable laminar flame was recorded across the reaction zone to investigate potential interferences. The results indicate that the single-photon channel, CH3 + 212.8 nm → CH (X 2Π) + H2, dominates the photofragmentation process. The CH2 radical was excluded from being an interfering precursor of the CH (X 2Π) fragments owing to its relatively low concentration and small absorption cross section. Naturally present CH in the flame was identified as the main interference, but was conservatively estimated to account for only less than 4% of the total PF-LIF signal. Signal-to-noise ratio of around 10 was realized for single-shot imaging of natural CH3 in turbulent jet flames.

Original languageEnglish
Pages (from-to)4487–4495
JournalProceedings of the Combustion Institute
DOIs
Publication statusPublished - 2017

Subject classification (UKÄ)

  • Energy Engineering

Free keywords

  • CH
  • Laser-induced fluorescence
  • Photofragmentation
  • Single-shot imaging
  • Turbulent methane/air flames

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