Soot Formation in a Turbulent Swirl Stabilized Laboratory Combustor

The effect of pressure and fuel composition on soot formation was studied using a high pressure, tubular laboratory burner with a swirl stabilized diffusion flame. A specially-designed water flushed probe was used to extract samples of soot and other combustion products for analysis. Measurements showed the expected increase of soot concentration with pressure only until a critical value of the Reynolds number was reached. After this point, no further increase of soot loading was observed with pressure rise. This behavior was found to be present when either kerosene or propane was used in the burner. At a suitably high Reynolds number, several fuels, closely related to JP-4, were tested in the burner. These fuel blends were constructed by adding cyclic compounds to the JP-4 so as to change its hydrogen-to-carbon ratio. It was found that the amount of soot formed scaled with this ratio, although the sooting effect of different blends with the same ratio were not identical.