NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Radiation and Mixing Properties of Buoyant Turbulent Diffusion Flames.


pdf icon 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.