Numerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperatures

Handle URI:
http://hdl.handle.net/10754/621749
Title:
Numerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperatures
Authors:
M. Al-Noman, Saeed; Choi, Sang Kyu; Chung, Suk-Ho ( 0000-0001-8782-312X )
Abstract:
Autoignition characteristics of laminar nonpremixed methane jet flames in high-temperature coflow air are studied numerically. Several flame configurations are investigated by varying the initial temperature and fuel mole fraction. At a relatively low initial temperature, a non-autoignited nozzle-attached flame is simulated at relatively low jet velocity. When the initial temperature is higher than that required for autoignition, two regimes are investigated: an autoignited lifted flame with tribrachial edge structure and an autoignited lifted flame with Mild combustion. The autoignited lifted flame with tribrachial edge exhibited three branches: lean and rich premixed flame wings and a trailing diffusion flame. Characteristics of kinetic structure for autoignited lifted flames are discussed based on the kinetic structures of homogeneous autoignition and flame propagation of stoichiometric mixture. Results showed that a transition from autoignition to flame propagation modes occurs for reasonably stoichiometric mixtures. The autoignited lifted flame with Mild combustion occurs when methane fuel is highly diluted with nitrogen. The kinetic structure analysis shows that the characteristics of Mild combustion can be treated as an autoignited lean premixed lifted flame. Transition behavior from Mild combustion to nozzle-attached flame was investigated by increasing the fuel mole fraction. As the maximum flame temperature increases with decreasing liftoff height, the kinetic structure showed a transition behavior from autoignition to flame propagation of a lean premixed flame. © 2016 The Combustion Institute
KAUST Department:
Clean Combustion Research Center
Citation:
M. Al-Noman S, Choi SK, Chung SH (2016) Numerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperatures. Combustion and Flame 171: 119–132. Available: http://dx.doi.org/10.1016/j.combustflame.2016.06.021.
Publisher:
Elsevier BV
Journal:
Combustion and Flame
Issue Date:
7-Jul-2016
DOI:
10.1016/j.combustflame.2016.06.021
Type:
Article
ISSN:
0010-2180
Appears in Collections:
Articles; Clean Combustion Research Center

Full metadata record

DC FieldValue Language
dc.contributor.authorM. Al-Noman, Saeeden
dc.contributor.authorChoi, Sang Kyuen
dc.contributor.authorChung, Suk-Hoen
dc.date.accessioned2016-11-03T13:24:07Z-
dc.date.available2016-11-03T13:24:07Z-
dc.date.issued2016-07-07en
dc.identifier.citationM. Al-Noman S, Choi SK, Chung SH (2016) Numerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperatures. Combustion and Flame 171: 119–132. Available: http://dx.doi.org/10.1016/j.combustflame.2016.06.021.en
dc.identifier.issn0010-2180en
dc.identifier.doi10.1016/j.combustflame.2016.06.021en
dc.identifier.urihttp://hdl.handle.net/10754/621749-
dc.description.abstractAutoignition characteristics of laminar nonpremixed methane jet flames in high-temperature coflow air are studied numerically. Several flame configurations are investigated by varying the initial temperature and fuel mole fraction. At a relatively low initial temperature, a non-autoignited nozzle-attached flame is simulated at relatively low jet velocity. When the initial temperature is higher than that required for autoignition, two regimes are investigated: an autoignited lifted flame with tribrachial edge structure and an autoignited lifted flame with Mild combustion. The autoignited lifted flame with tribrachial edge exhibited three branches: lean and rich premixed flame wings and a trailing diffusion flame. Characteristics of kinetic structure for autoignited lifted flames are discussed based on the kinetic structures of homogeneous autoignition and flame propagation of stoichiometric mixture. Results showed that a transition from autoignition to flame propagation modes occurs for reasonably stoichiometric mixtures. The autoignited lifted flame with Mild combustion occurs when methane fuel is highly diluted with nitrogen. The kinetic structure analysis shows that the characteristics of Mild combustion can be treated as an autoignited lean premixed lifted flame. Transition behavior from Mild combustion to nozzle-attached flame was investigated by increasing the fuel mole fraction. As the maximum flame temperature increases with decreasing liftoff height, the kinetic structure showed a transition behavior from autoignition to flame propagation of a lean premixed flame. © 2016 The Combustion Instituteen
dc.publisherElsevier BVen
dc.subjectAutoignitionen
dc.titleNumerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperaturesen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.identifier.journalCombustion and Flameen
dc.contributor.institutionKorea Institute of Machinery & Materials, Environmental and Energy Systems Research Division, Daejeon, South Koreaen
kaust.authorM. Al-Noman, Saeeden
kaust.authorChung, Suk-Hoen
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