Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number

Handle URI:
http://hdl.handle.net/10754/626037
Title:
Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number
Authors:
Yoon, Sung Hwan; Hu, Longhua; Fujita, Osamu ( 0000-0002-2947-8548 )
Abstract:
According to previous theory, pulsating propagation in a premixed flame only appears when the reduced Lewis number, β(Le-1), is larger than a critical value (Sivashinsky criterion: 4(1 +3) ≈ 11), where β represents the Zel'dovich number (for general premixed flames, β ≈ 10), which requires Lewis number Le > 2.1. However, few experimental observation have been reported because the critical reduced Lewis number for the onset of pulsating instability is beyond what can be reached in experiments. Furthermore, the coupling with the unavoidable hydrodynamic instability limits the observation of pure pulsating instabilities in flames. Here, we describe a novel method to observe the pulsating instability. We utilize a thermoacoustic field caused by interaction between heat release and acoustic pressure fluctuations of the downward-propagating premixed flames in a tube to enhance conductive heat loss at the tube wall and radiative heat loss at the open end of the tube due to extended flame residence time by diminished flame surface area, i.e., flat flame. The thermoacoustic field allowed pure observation of the pulsating motion since the primary acoustic force suppressed the intrinsic hydrodynamic instability resulting from thermal expansion. By employing this method, we have provided new experimental observations of the pulsating instability for premixed flames. The Lewis number (i.e., Le ≈ 1.86) was less than the critical value suggested previously.
KAUST Department:
Clean Combustion Research Center
Citation:
Yoon SH, Hu L, Fujita O (2018) Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number. Combustion and Flame 188: 1–4. Available: http://dx.doi.org/10.1016/j.combustflame.2017.09.026.
Publisher:
Elsevier BV
Journal:
Combustion and Flame
Issue Date:
12-Oct-2017
DOI:
10.1016/j.combustflame.2017.09.026
Type:
Article
ISSN:
0010-2180
Sponsors:
The author would like to acknowledge the support from these projects: A Grant-in-Aid for Scientific Research (KIBAN (B) No. 26289042) from MEXT Japan, Key project of National Natural Science Foundation of China (NSFC) under Grant No. 51636008 and Key Research Program of Frontier Sciences, Chinese Academy of Science (CAS) under Grant No. QYZDB-SSW-JSC029. The authors thank Dr. M. S. Cha for his valuable assistance.
Additional Links:
http://www.sciencedirect.com/science/article/pii/S0010218017303632
Appears in Collections:
Articles; Clean Combustion Research Center

Full metadata record

DC FieldValue Language
dc.contributor.authorYoon, Sung Hwanen
dc.contributor.authorHu, Longhuaen
dc.contributor.authorFujita, Osamuen
dc.date.accessioned2017-10-30T08:39:52Z-
dc.date.available2017-10-30T08:39:52Z-
dc.date.issued2017-10-12en
dc.identifier.citationYoon SH, Hu L, Fujita O (2018) Experimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis number. Combustion and Flame 188: 1–4. Available: http://dx.doi.org/10.1016/j.combustflame.2017.09.026.en
dc.identifier.issn0010-2180en
dc.identifier.doi10.1016/j.combustflame.2017.09.026en
dc.identifier.urihttp://hdl.handle.net/10754/626037-
dc.description.abstractAccording to previous theory, pulsating propagation in a premixed flame only appears when the reduced Lewis number, β(Le-1), is larger than a critical value (Sivashinsky criterion: 4(1 +3) ≈ 11), where β represents the Zel'dovich number (for general premixed flames, β ≈ 10), which requires Lewis number Le > 2.1. However, few experimental observation have been reported because the critical reduced Lewis number for the onset of pulsating instability is beyond what can be reached in experiments. Furthermore, the coupling with the unavoidable hydrodynamic instability limits the observation of pure pulsating instabilities in flames. Here, we describe a novel method to observe the pulsating instability. We utilize a thermoacoustic field caused by interaction between heat release and acoustic pressure fluctuations of the downward-propagating premixed flames in a tube to enhance conductive heat loss at the tube wall and radiative heat loss at the open end of the tube due to extended flame residence time by diminished flame surface area, i.e., flat flame. The thermoacoustic field allowed pure observation of the pulsating motion since the primary acoustic force suppressed the intrinsic hydrodynamic instability resulting from thermal expansion. By employing this method, we have provided new experimental observations of the pulsating instability for premixed flames. The Lewis number (i.e., Le ≈ 1.86) was less than the critical value suggested previously.en
dc.description.sponsorshipThe author would like to acknowledge the support from these projects: A Grant-in-Aid for Scientific Research (KIBAN (B) No. 26289042) from MEXT Japan, Key project of National Natural Science Foundation of China (NSFC) under Grant No. 51636008 and Key Research Program of Frontier Sciences, Chinese Academy of Science (CAS) under Grant No. QYZDB-SSW-JSC029. The authors thank Dr. M. S. Cha for his valuable assistance.en
dc.publisherElsevier BVen
dc.relation.urlhttp://www.sciencedirect.com/science/article/pii/S0010218017303632en
dc.subjectAcoustic instabilityen
dc.subjectCombustion instabilityen
dc.subjectDiffusive-thermal instabilityen
dc.subjectLewis numberen
dc.subjectPulsating instabilityen
dc.titleExperimental observation of pulsating instability under acoustic field in downward-propagating flames at large Lewis numberen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.identifier.journalCombustion and Flameen
dc.contributor.institutionDivision of Mechanical and Space Engineering, Hokkaido University, Kita13 Nishi 8, Kita-ku, Sapporo 060-8628, Hokkaido, Japanen
dc.contributor.institutionState Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, Chinaen
kaust.authorYoon, Sung Hwanen
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.