Soot properties characterization of aviation Jet A-1 laminar non-premixed coflow flame

Abstract

A canonical laminar coflow non-premixed flame was produced using a Jet A-1 fuel burning in coflowing ambient air environment using a Gülder type burner configuration. The aviation fuel was vaporized and carried by methane to the reaction zone. Non-intrusive laser-based multi-wavelength line-of-sight attenuation and emission measurements were employed to quantify soot properties in a spatially-resolved fashion. The experimental methodology allowed to evaluate soot properties such as temperature, absorption function, soot maturity, percentage of organic and graphitic compound contents, soot volume fraction and the divergence of the radiative heat flux.The distribution of soot temperature was found to be similar to that of alkenes and alkanes fuels, increasing radially toward the flame edge and axially toward the tip, peaking at 1950 K. The level of maturity was found to be higher (increased proportion of graphitic contents) in high soot temperature regions, revealing a relationship between temperature and the maturation process. Also, graphitic soot particles were predominantly found at the top of the flame, near the centerline zone and in the vicinity of the flame wings. As expected, the maturity influenced the absorption function, which was found to vary from 0.2 to 0.37 as the percentage of graphitic compounds changes from approximately 60% to 80% (mean values). This spatial variation of the absorption function led to significant differences on the retrieved soot volume fraction, around 1 ppm for the maximum values, as compared to the use of a constant value assuming fully graphitic soot particles. Despite these observations, the radiative heat flux released by the flame was not significantly affected, even considering the importance of taking into account the maturity for soot experimental diagnostics.