The Combustion Characteristics of n-Decane/Iso-Octane/Toluene Mixture and Jet-A Fuel Droplets in the Absence of Convection

Abstract

This study examines the extent to which a ternary mixture of n-decane/iso-octane/toluene in the specific mixture fraction of 42.67/33.02/24.31 (mole fraction), respectively, can replicate the droplet burning characteristics of an aviation fuel, Jet-A (designated by the Air Force as “POSF4658”). Experiments were carried out to examine the droplet combustion characteristics in an environment which minimizes convection to promote spherical symmetry in the burning process. The evolution of droplet diameter, burning rate and flame and soot stand-off ratios were compared to Jet-A to evaluate the potential of this ternary to serve as a Jet-A surrogate regarding the droplet burning process. The results show that the ternary blend has a shorter transient droplet heating period than Jet-A and it closely replicates the evolution of droplet diameter and burning rate. The burning rates for these two fuels are close at the end of burning, and flame and soot standoff ratios for the ternary are also reasonably close to those of Jet-A. The results also suggest that the spherical droplet flame configuration can be a useful tool to evaluate the extent to which a mixture of single component fuels may serve as a surrogate of a real transportation fuel.