The effect of elevated pressure on soot formation in a laminar jet diffusion flame

by McCrain, Laura Lynne

McCrain, Laura Lynne. The Effect of Elevated Pressure on Soot Formation in a Laminar Jet Diffusion Flame. Under the direction of Dr. William L. Roberts. Soot volume fraction (fsv) is measured quantitatively in a laminar diffusion flame at elevated pressures up to 25 atmospheres as a function of fuel type in order to gain a better understanding of the effects of pressure on the soot formation process. Methane and ethylene are used as fuels; methane is chosen since it is the simplest hydrocarbon while ethylene represents a larger hydrocarbon with a higher propensity to soot. Soot continues to be of interest because it is a sensitive indicator of the interactions between combustion chemistry and fluid mechanics and a known pollutant. To examine the effects of increased pressure on soot formation, Laser Induced Incandescence (LII) is used to obtain the desired temporally and spatially resolved, instantaneous fsv measurements as the pressure is incrementally increased up to 25 atmospheres. The effects of pressure on the physical characteristics of the flame are also observed. A laser light extinction method that accounts for signal trapping and laser attenuation is used for calibration that results in quantitative results. The local peak fsv is found to scale with pressure as p 1.2 for methane and p 1.7 for ethylene.