Radiation and Mixing Properties of Buoyant Turbulent Diffusion Flames.
Radiation and Mixing Properties of Buoyant Turbulent
Diffusion Flames.
(3608 K)
Koylu, U. U.; Dai, Z.; Tseng, L. K.; Faeth, G. M.
NIST GCR 93-631; 60 p. July 1993.
Sponsor:
National Institute of Standards and Technology,
Gaithersburg, MD
Available from:
National Technical Information Service
Order number: PB94-165974
Keywords:
diffusion flames; fire plumes; fire research; optical
properties; rayleigh light scattering; soot; soot
aggregates
Abstract:
Two aspects of unwanted fires were considered: (1) the
optical properties of soot in the fuel-lean region of
buoyant turbulent diffusion flames, and (2) the
structure and mixing properties of buoyant turbulent
plumes. The scattering, absorption and extinction
properties of soot were measured for conditions where
soot structure was known from earlier transmission
electron microscopy measurements. The measurements were
compared with predictions based on the
Rayleigh-Debye-Gans (RDG) scattering approximation for
polydisperse fractal aggregates. The present soot
aggregates exhibited significant departures from
Rayleigh scattering, however, the RDG polydisperse
fractual aggregate theory provided an acceptable basis
to treat their optical properties. The plume study
involved laser-induced iodine fluorescence measurements
of mean and fluctuating mixture fractions. The results
indicated that past measurements of plume properties
represent transitional plumes and that self-preserving
turbulent plumes are somewhat narrower, with higher
levels of mean and fluctuating mixture fractions near
the axis.
