Abstract
Two-dimensional (2D) distributions of temperature and species concentration are crucial information to understand PAH inception and soot formation in diffusion flames. We report a tunable diode laser absorption spectroscopy (TDLAS) measurement to reconstruct the temperature and carbon dioxide concentration profiles in axisymmetric methane co-flow diffusion flame. The TDLAS sensor selected the v(3) bandhead region of CO2 molecule at 4.2 um to ensure high temperature sensitivity and avoid ambient background absorption. A Fourier analysis Abel inversion transform algorithm was used to reconstruct 2D distribution of attenuation coefficient and showed higher inversion accuracy compared with other commonly used inversion methods. Evaluation of the reconstruction accuracy of the present Fourier analysis and traditional Onion Peeling algorithm was also performed using the simulated temperature and CO2 concentration profiles from CFD calculation. The experimental reconstructed temperature and CO2 volume fraction profiles were obtained and compared with thermocouple measurement and CFD simulation. The results show that the temperature from TDLAS measurement agrees well with CFD simulation. Flame temperature measured by thermocouple is lower compared with TDLAS and CFD because of the perturbation introduced by insertion of the thermocouple, especially at the edge of the flame.