Soot formation in weakly buoyant acetylene-fueled laminar jet diffusion flames burning in air

Conference · Sun Jan 01 04:00:00 EST 1995 · Combustion and Flame; (United States)

OSTI ID:6556476

Sunderland, P B; Koeylue, U O; Faeth, G M ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering

The structure and soot properties of weakly buoyant, acetylene-fueled, laminar jet diffusion flames were studied experimentally for combustion in air at pressures of 0.125--0.250 atm. The following measurements were made: soot volume fractions using laser extinction, temperatures using both thermocouples and multiline emission, soot structure using thermophoretic sampling and analysis by transmission electron microscopy, concentrations of major gas species using sampling and analysis by gas chromatography, and velocities using laser velocimetry. As distance increased along the axis of the present acetylene-fueled flames, significant soot formation began when temperatures exceeded roughly 1250 K, and ended when fuel-equivalence ratios decreased to roughly 1.7, where the concentration of acetylene became small. This behavior allowed observations of soot growth and nucleation for acetylene concentrations of 6 [times] 10[sup [minus]6]--1 [times] 10[sup [minus]3] and temperatures of 1,000--2,100 K. Over this range of conditions, soot growth rates were comparable to past observations of new soot in premixed flames, and after correction for effects of soot oxidation yielded essentially first-order growth with respect to acetylene concentrations with a negligible activation energy, and an acetylene/soot collision efficiency of 0.53%. Present measurements of soot nucleation rates also suggested first-order behavior with respect to acetylene concentrations but with an activation energy of 32 kcal/gmol and with rates that were significantly lower than earlier estimates in the literature. Nevertheless, uncertainties about the effects of soot oxidation and age on soot growth, and about effects of surface area estimates and translucent objects on soot nucleation, must be resolved in order to adequately define soot formation processes in diffusion flames.

• OSTI ID: 6556476
• Report Number(s): CONF-940711--
• Conference Information: Journal Name: Combustion and Flame; (United States) Journal Volume: 100:1-2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020800 -- Petroleum-- Waste Management
025000* -- Petroleum-- Combustion
ACETYLENE
ALKYNES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
COMBUSTION KINETICS
GAS ANALYSIS
HYDROCARBONS
KINETICS
MORPHOLOGY
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
SOOT
TEMPERATURE MEASUREMENT
YIELDS