Comparisons of the Soot Volume Fraction Using Gravimetric and Light Extinction Techniques.
Comparisons of the Soot Volume Fraction Using
Gravimetric and Light Extinction Techniques.
Choi, M. Y.; Mulholland, G. W.; Hamins, A.; Kashiwagi,
Combustion and Flame, Vol. 102, No. 1/2, 161-169, July
soot; light extinction; experiments; temperature;
Simultaneous optical and gravimetric measurements were
performed in the postflame region of an acetylene/air
premixed flame where the temperature of the soot/gas
mixture was reduced to 500 K through nitrogen dilution.
By combining gravimetric measurements of the collected
soot with soot density measurements using helium
pycnometry, an accurate value of the soot volume
fraction was obtained. The temperature and soot
concentration profiles were measured to compare the line
of sight light extinction measurement with the point
sampling gravimetric measurements. The soot volume
fraction obtained by light extinction measurements
overestimated the actual soot volume fraction by about a
factor of two. By calibrating the optical measurements
with the gravimetric soot volume fractions, a
dimensionless extinction coefficient, Ke, of 8.6 was
measured. This value is conjectured to be applicable
for soot generated for a variety of fuels and to be
valid for extinction wavelengths in the visible to the
near-infrared. It was also found that the mass specific
light extinction coefficient was found to be 8.0 m2/g
which is consistent with measurements reported in the
literature for a variety of fuels.