Damköhler number effects on soot formation and growth in turbulent nonpremixed flames

Handle URI:
http://hdl.handle.net/10754/566094
Title:
Damköhler number effects on soot formation and growth in turbulent nonpremixed flames
Authors:
Attili, Antonio; Bisetti, Fabrizio ( 0000-0001-5162-7805 ) ; Mueller, Michael E.; Pitsch, Heinz
Abstract:
The effect of Damköhler number on turbulent nonpremixed sooting flames is investigated via large scale direct numerical simulation in three-dimensional n-heptane/air jet flames at a jet Reynolds number of 15,000 and at three different Damköhler numbers. A reduced chemical mechanism, which includes the soot precursor naphthalene, and a high-order method of moments are employed. At the highest Damköhler number, local extinction is negligible, while flames holes are observed in the two lowest Damköhler number cases. Compared to temperature and other species controlled by fuel oxidation chemistry, naphthalene is found to be affected more significantly by the Damköhler number. Consequently, the overall soot mass fraction decreases by more than one order of magnitude for a fourfold decrease of the Damköhler number. On the contrary, the overall number density of soot particles is approximately the same, but its distribution in mixture fraction space is different in the three cases. The total soot mass growth rate is found to be proportional to the Damköhler number. In the two lowest Da number cases, soot leakage across the flame is observed. Leveraging Lagrangian statistics, it is concluded that soot leakage is due to patches of soot that cross the stoichiometric surface through flame holes. These results show the leading order effects of turbulent mixing in controlling the dynamics of soot in turbulent flames. © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
KAUST Department:
Clean Combustion Research Center; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program; Reactive Flow Modeling Laboratory (RFML)
Publisher:
Elsevier BV
Journal:
Proceedings of the Combustion Institute
Issue Date:
2015
DOI:
10.1016/j.proci.2014.05.084
Type:
Article
ISSN:
1540-7489
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program; Clean Combustion Research Center

Full metadata record

DC FieldValue Language
dc.contributor.authorAttili, Antonioen
dc.contributor.authorBisetti, Fabrizioen
dc.contributor.authorMueller, Michael E.en
dc.contributor.authorPitsch, Heinzen
dc.date.accessioned2015-08-12T09:28:00Zen
dc.date.available2015-08-12T09:28:00Zen
dc.date.issued2015en
dc.identifier.issn1540-7489en
dc.identifier.doi10.1016/j.proci.2014.05.084en
dc.identifier.urihttp://hdl.handle.net/10754/566094en
dc.description.abstractThe effect of Damköhler number on turbulent nonpremixed sooting flames is investigated via large scale direct numerical simulation in three-dimensional n-heptane/air jet flames at a jet Reynolds number of 15,000 and at three different Damköhler numbers. A reduced chemical mechanism, which includes the soot precursor naphthalene, and a high-order method of moments are employed. At the highest Damköhler number, local extinction is negligible, while flames holes are observed in the two lowest Damköhler number cases. Compared to temperature and other species controlled by fuel oxidation chemistry, naphthalene is found to be affected more significantly by the Damköhler number. Consequently, the overall soot mass fraction decreases by more than one order of magnitude for a fourfold decrease of the Damköhler number. On the contrary, the overall number density of soot particles is approximately the same, but its distribution in mixture fraction space is different in the three cases. The total soot mass growth rate is found to be proportional to the Damköhler number. In the two lowest Da number cases, soot leakage across the flame is observed. Leveraging Lagrangian statistics, it is concluded that soot leakage is due to patches of soot that cross the stoichiometric surface through flame holes. These results show the leading order effects of turbulent mixing in controlling the dynamics of soot in turbulent flames. © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.en
dc.publisherElsevier BVen
dc.subjectDamköhler number effectsen
dc.subjectDirect numerical simulationsen
dc.subjectSooten
dc.subjectSoot leakageen
dc.subjectTurbulent flamesen
dc.titleDamköhler number effects on soot formation and growth in turbulent nonpremixed flamesen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMechanical Engineering Programen
dc.contributor.departmentReactive Flow Modeling Laboratory (RFML)en
dc.identifier.journalProceedings of the Combustion Instituteen
dc.contributor.institutionPrinceton Univ, Princeton, NJ 08544 USAen
dc.contributor.institutionUniv Aachen, Aachen, Germanyen
kaust.authorAttili, Antonioen
kaust.authorBisetti, Fabrizioen
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