Modeling of Oxidation-Driven Soot Aggregate Fragmentation in a Laminar Coflow Diffusion Flame

Abstract

In this study, three different oxidation-driven soot aggregate fragmentation models with 1:1, 2:1, and 10:1 fragmentation patterns are developed and implemented into a laminar coflow ethylene/air diffusion flame, together with a pyrene-based soot model and a sectional aerosol dynamics model. It is found that the average degree of particle aggregation (n _p ) in the soot oxidation region is not correctly predicted if oxidation-driven aggregate fragmentation is neglected; whereas the incorporation of aggregate fragmentation significantly improves the n _p prediction in the soot oxidation region. Similar results are obtained using the 1:1 and 2:1 fragmentation patterns. However, as the pattern ratio increases to 10:1, appreciable difference in the predicted n _p is observed. As the pattern ratio becomes larger, the fragmentation effect diminishes and the predicted n _p approaches that of the original model neglecting fragmentation.

Keywords:

• Fragmentation pattern
• Laminar coflow diffusion flame
• Oxidation-driven soot aggregate fragmentation
• Soot modeling

ACKNOWLEDGEMENTS

The authors gratefully acknowledge AUTO21™ for the financial support of this project as well as Dr. J. Z. Wen, Dr. S. H. Park, and Dr. S. N. Rogak for the helpful discussions on the sectional aerosol dynamics model.