Modeling and Measurements of Soot and Species in a Laminar Diffusion Flame.
Modeling and Measurements of Soot and Species in a
Laminar Diffusion Flame.
(977 K)
Kennedy, I. M.; Yam, C.; Rapp, D. C.; Santoro, R. J.;
Tsang, W.
Combustion and Flame, Vol. 107, No. 4, 368-382,
December 1996.
Sponsor:
Air Force Office of Scientific Research, Washington, DC
Keywords:
soot; laminar flames; diffusion flames; ethene; chemical
reactions; equations
Abstract:
A model of laminar, soot-laden ethene diffusion flames
has been developed and compared with measurements in
nonsooting and sooting flames. Concentrations of stable
gas-phase species were measured with mass spectrometry;
laser-induced fluorescence was used to measure the OH
concentrations. A system of elementary reactions was
used to describe the gas-phase chemistry. The model
incorporated a simple description of the growth of soot
which assumed that acetylene was the only growth
species. Soot formation was coupled with the flame
chemistry via the loss of acetylene and OH on soot and
the production of CO during soot oxidation. The model
predicted most of the gas-phase species quite well, with
the exception of OH. The loadings of soot in the flames
were reporduced adequately, although less success was
achieved in predicting the transition from nonsooting to
sooting conditions. Details concerning the products of
soot oxidation by OH were found to be important with
regard to the flame chemistry. The inclusion of soot in
the flame model had a significant impact on the
predicted structure of the flame as seen in changes to
the formation and destruction rates of OH on the fuel
side of the flame. The rate of OH reaction with soot in
the midregion of the flame was small compared with the
rate of reaction of OH with CO. However, the two rates
became comparable in the soot burnout zone.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899