Soot propensity of Eucalyptus globulus laminar flames at different coflow indices

This study investigates the soot production in stable and axisymmetric laminar flames from dried Eucalyptus globulus leaves of reduced size under three different coflow indices in a well-controlled burning configuration. Soot temperature and volume fraction fields of high spatial resolution were determined from light extinction and flame emission measurements. Soot volume fraction increased over time in each coflow case, while higher coflows resulted in a reduction in the overall soot accumulation due to enhanced dilution and oxidation. Soot emissions in this work were comparable to those of methane and significantly lower than those of other conventional fuels. The divergence of the radiative heat flux and soot radiation exhibited a decline over time and at higher coflows. Non-dimensional correlations between flame height, heat release rate, and radiant fraction were developed, showing exponential relationships between mass loss and flame radiation to the fuel bed. These results demonstrated that higher coflow rates resulted in shorter, more homogeneous flames with reduced soot production, underscoring the influence of controlled airflow on combustion efficiency. This work offers a comprehensive experimental characterization of soot production in laminar flames replicable to other wildland fuels, thus contributing to improving the quantification of fire emissions.