Mid‐infrared multiline absorption tomography for in situ analysis of thermochemical structure in natural gas‐fired cooker flame.

A mid‐infrared laser absorption tomography technique was developed to quantify the nonuniform thermochemical structures of flames stabilized on a natural gas‐fired cooker. Multispectral absorption spectroscopy coupled with Tikhonov‐regularized three‐point Abel inversion was used to resolve the spatially resolved temperature and species concentration. A tunable interband cascade laser (ICL) near 4.2 μm was used to access multiple CO2 absorption lines in the fundamental vibration band. Multiline Voigt fitting strategy was used to improve the fitting of the overlap absorption features. Comprehensive measurements at a different height above the cooker were performed and assembled to display the contour of temperature and CO2 concentrations, resolving the nonuniform thermochemical structure of the high‐temperature combustion field. The measurement uncertainty analysis for temperature and CO2 concentration was also discussed. The current technique is demonstrated to be capable of quantitatively distinguishing flame conditions under different fuel supply modes. [ABSTRACT FROM AUTHOR]