Experimental validation of two-dimensional temperature tomography based on laser absorption spectroscopy in a flat flame burner

Abstract This study presents an experimental validation of a two-dimensional temperature reconstruction of a premixed methane/air flat flame using tunable diode laser absorption tomography (TDLAT). Two H 2 O absorption lines near 7185.6 and 7444.36 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mtext>cm</mml:mtext> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> were employed for two-line thermometry, with integrated absorbance data collected across a 5 × 5 laser beam grid. A modified algebraic reconstruction technique was used to retrieve spatially resolved temperature fields at various equivalence ratios. The reconstructed results revealed expected radial temperature distributions, with higher temperatures near the flame core and lower values toward the edges due to heat losses. Experimental validation was performed through comparison with coherent anti-Stokes Raman scattering measurements under identical conditions, demonstrating good agreement. Additional comparison with thermocouple data further emphasized the improved accuracy and non-intrusive nature of optical diagnostics. This work addresses a key limitation of previous TDLAT studies by providing direct validation through comparison with an independent optical technique. The results confirm the reliability of TDLAT for quantitative flame diagnostics and combustion research.