Post-Flame Soot. Final Report. September 1994-December 1995.
Post-Flame Soot. Final Report. September 1994-December
Sorensen, C. M.
NIST GCR 96-694; 34 p. June 1996.
Sponsor:National Institute of Standards and Technology,
Available from: National Technical Information Service
Order number: PB96-193701
soot; acetylene; diffusion flames; flame research; light
scattering; smoke; sphere sizes
The smoke agglomerates produced by a co-annular
diffusion flame with acetylene fuel were characterized
by sampling/microscopy and light scattering
measurements. Particles were sampled at various heights
above the flame using both thermophoretic sampling and
impaction. Transmission electron microscopy was used for
the smaller agglomerates obtained by thermophoretic
sampling and optical microscopy was used for analysis of
particles as large as .4 mm in diamter collected by
impaction. The number of primary spheres was estimated
from the projected area of the agglomerate and the
primary sphere size. The fractal analysis extended over
four orders of magnitude in the radius of gyration - the
widest range studied for smokes. The fractal dimension
and the prefactor were determined for smoke collected
for a range of heights above the flame. The structure
factor measurements were performed for angles ranging
from 1DG to 150DG as a function of height and fuel flow.
No Guinier regime was observed at a flow rate of 30
ml/min. Modeling results suggest that the slight dip in
the structure factor measurements might result from
intercluster scattering. A condition for the transition
from Brownian agglomeration to gelation is derived.