Laminar premixed methane-air flame; Laser-induced breakdown spectroscopy; Flames structure; Radial distribution;BURNING COAL PARTICLE; POLARIZATION SPECTROSCOPY; ANALYTICAL TOOL; ATOMIC SODIUM; JET FLAME; SPECTROMETRY; OH; TEMPERATURE; SPARK; RATIO

Laser-induced breakdown spectroscopy was evaluated for the analysis of the structure of laminar premixed methane-air flames. Firstly, breakdown threshold pulse energy and plasma energy in different areas of the flame were measured simultaneously, and an approximate linear relation between them was detected. Secondly, a new approach was proposed to qualitatively characterize the flame temperature distributions based on the plasma energy distributions. Finally, combination of the spatial analysis of the spectrum intensity, plasma energy and equivalence ratio, the laminar premixed flames structure was investigated deeply, including the distribution of the flame temperature, the width and distribution of different flame region (e.g. premixed combustion regions, high temperature regions.),as well as the location of the flame front. (C) 2017 Elsevier B.V. All rights reserved.