Experimental Study on Temperature, Soot Volume Fraction Distributions, and Self-Absorption Effect of a Laminar Diffusion Flame

— In this paper, an axisymmetric ethylene laminar diffusion flame generated with 194 mL/min ethylene and 284 L/min air flow is experimentally investigated. A hyperspectral imaging device was used to capture radiation images at multiple wavelengths. In order to reduce errors caused by the data capturing time difference, the device was placed on its side, thereby making the data that was at the same height away from the fuel nozzle captured almost at the same time. The radiation transfer process was iteratively reconstructed while considering the self-absorption effect, and using a method that searched the temperature which had an inversely fitted spectral line closest to the reconstructed one. Moreover, a method that traces discrete radiation beams and records energy absorbed during transfer for quantitatively analyzing the self-absorption effect is also proposed. Analysis was also conducted. Results show that, at the flame root, the main reaction takes place beyond the areas right above the fuel nozzle. As height increases, the most violent reaction areas move inside. Quite a lot of soot aggregates exist in the flame center of the upper part of the flame. The self-absorption effect has more influence on the areas with lower temperatures and higher soot volume fractions.