Temperature imaging of Counterflow Diffusion Flames by using TDLAS Tomography

Counterflow flames are used as reference flames in combustion modeling and evaluations for their high stability, good flame curvature profile and ease to control. Experimental research for counterflow flames in the literature were mostly carried out only along axis. In this work, computational fluid dynamics (CFD) simulations were introduced and counterflow diffusion flames are imaged by using tunable diode laser absorption spectroscopy (TDLAS). For circular symmetrical flames in this case, the inverse Radon transform rather than typical inverse Abel transform is used to reconstruct temperature distributions in the flame cross sections, for the regularization involved in the filtered back projection in the inverse Radon transform. Also, two reconstructed methods based on integrated absorbance and pixel absorbance were respectively implemented and compared in the aspects of temperature distributions. Temperature distribution from the experimental setup were captured over cross-sections of flames at different heights. The three-dimensional profile of the flames recovered from these cross-sectional images agreed well with the numerically simulated flame in the CFD simulations.