Soot particle size distributions in premixed flames of RP-3 jet fuel and its distillates

Abstract

Particle size distributions in premixed burner-stabilized stagnation (BSS) flames of a Chinese RP-3 jet fuel and its three distillate fractions, namely the 0–50%, 50%–90%, 90%–100% distillate fractions, were experimentally measured. The cold gas velocity and C/O ratio in the mixture were kept constant, and the maximum temperatures were similar in the four flames. As the separation distance between the burner and the stagnation plate was above 6 mm, the particle size distribution functions (PSDFs) of the four flames showed bimodal distribution, i.e. nucleation and accumulation modes. With increased separation distance between the burner and the stagnation plate, the accumulation strength increased in all the flames. The 90%–100% distillate fraction showed higher nucleation strength but lower accumulation strength than the other fuels, and thus a higher number of particles and slower particle growth rates. In contrast, the 0–50% distillate fraction exhibited higher accumulation strength than the other fuels. The 50%–90% distillate fraction and the RP-3 jet fuel presented intermediate nucleation and accumulation strengths between those of the 0–50% and 90%–100% distillate fractions. The soot morphology observation from transmission electron microscopy also indicated that the 90%–100% distillate fraction produced smaller primary particle sizes than the other fuels, suggesting their slower particle growth rates.