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2019-07-09Zeitschriftenartikel DOI: 10.18452/21631
On the emergence of large clusters of acoustic power sources at the onset of thermoacoustic instability in a turbulent combustor
dc.contributor.authorKrishnan, Abin
dc.contributor.authorR I, Sujith
dc.contributor.authorMarwan, Norbert
dc.contributor.authorKurths, Juergen
dc.date.accessioned2020-08-11T12:05:35Z
dc.date.available2020-08-11T12:05:35Z
dc.date.issued2019-07-09none
dc.identifier.other10.1017/jfm.2019.429
dc.identifier.urihttp://edoc.hu-berlin.de/18452/22387
dc.description.abstractIn turbulent combustors, the transition from stable combustion (i.e. combustion noise) to thermoacoustic instability occurs via intermittency. During stable combustion, the acoustic power production happens in a spatially incoherent manner. In contrast, during thermoacoustic instability, the acoustic power production happens in a spatially coherent manner. In the present study, we investigate the spatiotemporal dynamics of acoustic power sources during the intermittency route to thermoacoustic instability using complex network theory. To that end, we perform simultaneous acoustic pressure measurement, high-speed chemiluminescence imaging and particle image velocimetry in a backward-facing step combustor with a bluff body stabilized flame at different equivalence ratios. We examine the spatiotemporal dynamics of acoustic power sources by constructing time-varying spatial networks during the different dynamical states of combustor operation. We show that as the turbulent combustor transits from combustion noise to thermoacoustic instability via intermittency, small fragments of acoustic power sources, observed during combustion noise, nucleate, coalesce and grow in size to form large clusters at the onset of thermoacoustic instability. This nucleation, coalescence and growth of small clusters of acoustic power sources occurs during the growth of pressure oscillations during intermittency. In contrast, during the decay of pressure oscillations during intermittency, these large clusters of acoustic power sources disintegrate into small ones. We use network measures such as the link density, the number of components and the size of the largest component to quantify the spatiotemporal dynamics of acoustic power sources as the turbulent combustor transits from combustion noise to thermoacoustic instability via intermittency.eng
dc.language.isoengnone
dc.publisherHumboldt-Universität zu Berlin
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectturbulent reacting flowseng
dc.subjectvortex dynamicseng
dc.subject.ddc532 Mechanik der Fluidenone
dc.titleOn the emergence of large clusters of acoustic power sources at the onset of thermoacoustic instability in a turbulent combustornone
dc.typearticle
dc.identifier.urnurn:nbn:de:kobv:11-110-18452/22387-5
dc.identifier.doihttp://dx.doi.org/10.18452/21631
dc.type.versionpublishedVersionnone
local.edoc.container-titleJournal of Fluid Mechanicsnone
local.edoc.pages28none
local.edoc.anmerkungThis publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.none
local.edoc.type-nameZeitschriftenartikel
local.edoc.institutionMathematisch-Naturwissenschaftliche Fakultätnone
local.edoc.container-typeperiodical
local.edoc.container-type-nameZeitschrift
local.edoc.container-publisher-nameCambridge University Pressnone
local.edoc.container-volume874none
local.edoc.container-firstpage455none
local.edoc.container-lastpage482none
dc.description.versionPeer Reviewednone

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