Study on Two-dimensional Images of Soot Distributions in Laminar Diffusion Flames of Liquid Fuelsat Elevated Pressure by Laser Induced Incandescence (LII)

This research focuses on the effects of an increasing pressure on the soot formation during combustion of vaporized liquid fuel. Firstly, soot formation is measured in a laminar diffusion flame of n-heptane up to 3.0 bar. The soot volume fraction in the diffusion flames has been measured using Laser Induced Incandescence (LII) calibrated by means of the Line of Sight Attenuation (LOSA) technique. The 2-D images of soot distributions have been captured, and the integral soot volume fractions show power law dependence on pressures. Secondly, a specially designed High fueling system (called “doped flame”) is presented in this paper. This setup allows for soot measurements in laminar diffusion flames of liquid fuel blends at elevated pressure. Fuels with two typical molecular structures, namely linear and saturated cyclic hydrocarbons, are examined in both non-oxygenated (n-hexane and cyclohexane) and oxygenated form (1-hexanol and cyclohexanol). The experiment data suggests that soot is more prevalent for cyclic structures relative to their linear counterparts.