Particulate volume fractions in diffusion flames

1979 ◽  
Vol 17 (1) ◽  
pp. 1017-1028 ◽  
Author(s):  
P.J. Pagni ◽  
S. Bard
Keyword(s):  
Diffusion Flames ◽  
Volume Fractions ◽  
Particulate Volume

scholarly journals Soot Volume Fraction Profiles in Forced-Combusting Boundary Layers

1983 ◽  
Vol 105 (1) ◽  
pp. 159-165 ◽  
Author(s):  
R. A. Beier ◽  
P. J. Pagni
Keyword(s):  
Boundary Layer ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Volume Fraction ◽  
Liquid Hydrocarbon ◽  
Forced Flow ◽  
Volume Fractions ◽  
Ambient Oxygen ◽  
Mass Fractions

A multiwavelength laser transmission technique is used to determine soot volume fraction fields and aproximate particle size distributions in a forced flow combusting boundary layer. Measurements are made in diffusion flames of polymethylmethacrylate (PMMA) and five liquid hydrocarbon fuels (n-heptane, iso-octane, cyclohexane, cyclohexene, and toluene) with ambient oxygen mass fractions in the range of 0.23 ≲ Y0∞ ≲ 0.50. Soot is observed in a region between the pyrolyzing fuel surface and the flame zone. Soot volume fraction increases monotonically with Y0∞, e.g., n-heptane and PMMA are similar with soot volume fractions, fν, ranging from fν ∼ 5 × 10−7 at Y0∞ = 0.23 to fν ∼ 5 × 10−6 at Y0∞ = 0.50. For an oxygen mass fraction the same as air, Y0∞ = 0.23, soot volume fractions are approximately the same as values previously reported in pool fires and a free combusting boundary layer. However, the shape of the fν profile changes with more soot near the flame in forced flow than in free flow due to the different y-velocity fields in these two systems. For all fuels tested, a most probable particle radius is between 20 nm and 80 nm, and does not appear to change substantially with location, fuel, or oxygen mass fraction.

Characterization of Particulate From Fires Burning Silicone Fluids

2000 ◽  
Vol 123 (6) ◽  
pp. 1093-1097 ◽  
Author(s):  
Yudaya Sivathanu ◽  
Anthony Hamins ◽  
George Mulholland ◽  
Takashi Kashiwagi ◽  
Robert Buch
Keyword(s):  
Hydrocarbon Flame ◽  
Burner Surface ◽  
Hydrocarbon Flames ◽  
Volume Fractions ◽  
Multi Wavelength ◽  
Wavelength Absorption ◽  
Gravimetric Sampling ◽  
Dominant Part ◽  
Particulate Volume

The optical properties of particulate emitted from fires burning two distinct polydimethylsiloxane fluids (D4 and M2 or MM, where D=CH32SiO and M=CH33SiO2) were obtained using a transmission cell-reciprocal nephelometer in conjunction with gravimetric sampling. The specific absorption coefficient of particulate ash from fires burning D4 and MM is significantly lower than that of particulate soot from an acetylene (hydrocarbon) flame. Scattering is the dominant part of extinction in fires burning the silicone fluids. This is very different from extinction by soot particles in hydrocarbon fires, where absorption is approximately five times greater than scattering. Temperatures and particulate volume fractions along the axis of a silicone fire D4 were measured using multi-wavelength absorption/emission spectroscopy. The structure of the D4 flames is markedly different from hydrocarbon flames. The temperatures and particulate volume fractions very close to the burner surface are much higher than in comparably sized hydrocarbon flames.

scholarly journals Carbon Particulate in Small Pool Fire Flames

1981 ◽  
Vol 103 (2) ◽  
pp. 357-362 ◽  
Author(s):  
S. Bard ◽  
P. J. Pagni
Keyword(s):  
Light Transmission ◽  
Diffusion Flames ◽  
Pool Fire ◽  
Small Scale ◽  
Flame Radiation ◽  
Volume Fractions ◽  
Distribution Form ◽  
Multi Wavelength ◽  
Two Parameters ◽  
Carbon Particulate

Flame radiation, the dominant heat transfer mechanism in many combustion and fire safety related problems, is primarily controlled by the fraction of flame volume occupied by solid carbon particulate. A multi-wavelength laser transmission technique is used here to measure carbon particulate volume fractions and approximate particle size distributions in ten common solid, cellular and liquid fueled small scale, 0 (10 cm dia), pool fire diffusion flames. The most probable particle radius, rmax, and concentration, N0, are two parameters in the assumed gamma function size distribution form which are determined for each fuel by simultaneously measuring light transmission of two superimposed laser wavelengths. The resulting soot volume fractions range from fv ∼ 4 × 10−6 for cellular polystyrene to fv ∼ 7 × 10−8 for alcohol. Cellular polystyrene has the largest particles, rmax ∼ 60 nm while wood has the smallest, rmax ∼ 20 nm. The carbon particulate optical properties used in the analysis are shown to be representative of actual flame soot and are more accurate than the soot refractive index usually assumed in the literature. Finally, mean particle sizes obtained for all fuels indicate that the small particle absorption limit assumption is a reasonable approximation for infrared flame radiation calculations.

LEWIS NUMBER AND VAPORIZATION EFFECTS IN SPRAY DIFFUSION FLAMES

1993 ◽  
Vol 3 (4) ◽  
pp. 437-462 ◽  
Author(s):  
J. Barry Greenberg ◽  
I. Shpilberg
Keyword(s):  
Diffusion Flames ◽  
Lewis Number
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