Sooting Propensities of FACE Gasolines in Counterflow Nonpremixed Flames

To combat the negative health and environmental effects that accompany the continued consumption of hydrocarbon fuels, progress is being made to better facilitate clean combustion. Reducing the formation of particulate soot during practical combustion phenomena, e.g., within internal combustion engines, remains a critical challenge. The focus of this study is to provide a detailed characterization of the sooting propensities of three research-grade gasolines, namely FACE (Fuels for Advanced Combustion Engines) F, G, and J, developed by Chevron Phillips Chemical Company. Specifically, laser-induced incandescence (LII) is used to measure spatially resolved soot volume fraction profiles at varying strain rates and reactant concentrations in counterflow nonpremixed flames. LII results are accompanied by planar laser-induced fluorescence (PLIF) measurements of OH radicals for identifying flame sheet locations. In addition, particle image velocimetry (PIV) is used to characterize flow fields. The combination of LII, OH-PLIF, and PIV data sets results in a comprehensive description of soot formation in counterflow flames, which can be used to validate soot models for the combustion of gasoline fuels and to improve upon the fuel property database of FACE gasolines so that the sooting propensities of surrogate fuels can be quantitatively compared to those of their target real fuels. Experimental results show that the soot yield of FACE F is significantly less than those of FACE G and J, while the soot yield disparity between FACE G and J, which have similar aromatic content by volume, can be attributed to differing volumetric percentages of large (≥C9) single-ringed aromatic species.