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Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric PressureThe flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation--O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.
Document ID
20020087743
Acquisition Source
Glenn Research Center
Document Type
Reprint (Version printed in journal)
Authors
Xu, F.
(Michigan Univ. Ann Arbor, MI United States)
Faeth, G. M.
(Michigan Univ. Ann Arbor, MI United States)
Urban, D. L.
Yuan, Z.-G.
Date Acquired
August 20, 2013
Publication Date
December 15, 2001
Publication Information
Publication: Soot Formation in Freely-Propagating Laminar Premixed Flames
ISSN: 0010-2180
Subject Category
Inorganic, Organic And Physical Chemistry
Funding Number(s)
CONTRACT_GRANT: NAG3-2048
CONTRACT_GRANT: NAG3-1245
CONTRACT_GRANT: NAG3-1878
Distribution Limits
Public
Copyright
Other

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