EXPERIMENTAL AND NUMERICAL STUDIES OF SULFATE AND ORGANIC CONDENSATION ON AIRCRAFT ENGINE SOOT

To study the condensation of sulfates and organics on aircraft engine soot, a systematic measurement of particulate matter was performed using a sector rig combustor at various operation conditions and sampling configurations. The condensation of organics increased with increasing soot loading, although the initial vapor phase concentration was lower for the high soot condition. The condensation rate of the organic species is much slower than that of the sulfates, and therefore the availability of the soot surfaces becomes a rate-limiting factor. On the other hand, because the sulfates are nearly completely condensed on soot surfaces even for the low soot conditions, more soot did not significantly increase the condensation of sulfates. The experimental results were explained with a microphysical simulation by using a 6-species surrogate model to represent volatile aircraft emissions. Using the relative composition of the volatile organics based on saturation vapor concentration, and the dry mass accommodation coefficient derived from the correlation to water solubility the proposed surrogate model was able to match the experimental measurements both qualitatively and quantitatively.