Soot Scattering Measurements in the Visible and Near-Infrared Spectrum.
Soot Scattering Measurements in the Visible and
Near-Infrared Spectrum.
(388 K)
Zhu, J.; Choi, M. Y.; Mulholland, G. W.; Gritzo, L. A.
Combustion Institute, Symposium (International) on
Combustion, 28th. Proceedings. Volume 1. July
20-August 4, 2000, Edinburgh, Scotland, Combustion
Institute, Pittsburgh, PA, Candel, S.; Driscoll, J. F.;
Burgess, A. R.; Gore, J. P., Editor(s)(s), 439-446 pp,
2000.
Keywords:
combustion; in situ combustion; soot; diffusion flames;
laminar flames; extinction
Abstract:
Scattering to extinction cross-section ratios were
measured using the NIST Large Agglomerate Optics
Facility for soot produced from ethene and acetylene
laminar diffusion flames. Measurements were performed
using light sources at 543.5 nm, 632.8 nm, and 856 nm.
The average scattering to extinction cross-section
ratios for these wavelengths are equal to 0.245, 0.195,
and 0.195 for ethene and 0.311, 0.228, and 0.237 for
acetylene. The 856 nm measurements represent the longest
wavelength for which accurate scattering measurements
have been performed for soot. The size distribution and
fractal properties of the two soots were determined to
assess the effects of limited acceptance angle range,
finite size of the sensor, and departure from cosine
response on the uncertainty in the measurement. The
expanded relative uncertainty (95% confidence level) was
found to be + or - 6% at the two visible wavelengths and
+ or - 8% at 856 nm. Both the magnitude and wavelength
dependence of pse for the present experiments are
significantly different from those reported by Krishnan
et al for overfire soot produced using a turbulent
flame. The results are compared with the predictions of
fractal optics.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899