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Published 2011 | public
Journal Article

Modeling the oxidation-induced fragmentation of soot aggregates in laminar flames

Abstract

While the formation and growth of soot particles has received much attention, the subsequent destruction of the particles is less well understood. Soot particles are destroyed though two parallel processes: oxidation and fragmentation. Oxidation is the removal of mass from particles due to chemical reactions with molecular oxygen and hydroxyl radicals. Fragmentation is the break-up of large aggregates into smaller aggregates. Here, a new model for fragmentation inspired by previous experimental investigations is proposed and formulated within the Hybrid Method of Moments (HMOM). With the formulation, the rate of particle loss due to oxidation is closed, resolving a long-standing problem with the Method of Moments. Less important, secondary unclosed terms are introduced, and models for these terms are proposed. The oxidation and fragmentation models are validated using a set of laminar premixed methane flames and then applied to a series of laminar counterflow diffusion acetylene flames. The role of fragmentation is distinctly different in the two flame types. In the premixed flames, fragmentation only occurs in lean flames with a high oxygen concentration. In the diffusion flames, fragmentation is virtually absent, for soot passes through an OH radical layer and is completely oxidized before reaching high oxygen concentrations.

Additional Information

© 2010 The Combustion Institute. Published by Elsevier Inc. Available online 9 August 2010. The authors gratefully acknowledge funding from the National Aeronautics and Space Administration (NASA) and the Strategic Environmental Research and Development Program (SERDP). M.E.M. gratefully acknowledges funding from the National Defense Science and Engineering Graduate (NDSEG) fellowship program.

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023