Computational and experimental study of soot formation in a coflow, laminar diffusion flame

Citation
Md. Smooke et al., Computational and experimental study of soot formation in a coflow, laminar diffusion flame, COMB FLAME, 117(1-2), 1999, pp. 117-139
Citations number
40
Categorie Soggetti
Mechanical Engineering
Journal title
COMBUSTION AND FLAME
ISSN journal
00102180 → ACNP
Volume
117
Issue
1-2
Year of publication
1999
Pages
117 - 139
Database
ISI
SICI code
0010-2180(199904)117:1-2<117:CAESOS>2.0.ZU;2-P
Abstract
A detailed soot growth model in which the equations for particle production have been coupled to the flow and gaseous species conservation equations h as been developed for an axisymmetric, laminar, coflow diffusion flame. Res ults from the model have been compared to experimental data for a confined methane-air flame. The two-dimensional system couples detailed transport an d finite rate chemistry in the gas phase with the aerosol equations in the sectional representation. The formulation includes detailed treatment of th e transport, inception, surface growth, oxidation, and coalescence of soot particulates. Effects of thermal radiation and particle scrubbing of gas-ph ase growth and oxidation species are also included. Predictions and measure ments of temperature, soot volume fractions, and selected species are compa red over a range of heights and as a function of radius. Flame heights are somewhat overpredicted and local temperatures and volume fractions are unde rpredicted. We believe the inability to reproduce accurately bulk flame par ameters directly inhibits the ability to predict soot volume fractions and these differences are likely a result of uncertainties in the experimental inlet conditions. Predictions of the distributions of particle sizes indica te the existence of (relatively) low-molecular-weight species along the cen terline of the burner and trace amounts of the particles that escape from t he flame, unoxidized. Oxidation of particulates is dominated by reactions w ith hydroxyl radicals which attain levels approximately 10 times higher tha n calculated equilibrium levels. Gas cooling effects due to radiative loss are shown to have a very significant effect on predicted soot concentration s. (C) 1999 by The Combustion Institute.