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dc.contributor.author
Fong, Kee Onn
dc.contributor.author
Coletti, Filippo
dc.date.accessioned
2023-01-18T09:16:35Z
dc.date.available
2021-12-25T03:52:51Z
dc.date.available
2022-02-24T15:25:14Z
dc.date.available
2022-03-02T10:30:42Z
dc.date.available
2023-01-18T09:16:35Z
dc.date.issued
2022-02-25
dc.identifier.issn
0022-1120
dc.identifier.issn
1469-7645
dc.identifier.other
10.1017/jfm.2021.1024
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/522312
dc.identifier.doi
10.3929/ethz-b-000522312
dc.description.abstract
In collisional gas–solid flows, dense particle clusters are often observed that greatly affect the transport properties of the mixture. The characterisation and prediction of this phenomenon are challenging due to limited optical access, the wide range of scales involved and the interplay of different mechanisms. Here, we consider a laboratory setup in which particles fall against upward-moving air in a square vertical duct: a classic configuration in riser reactors. The use of non-cohesive, monodispersed, spherical particles and the ability to independently vary the solid volume fraction (Φ(V) = 0.1 %–0.8 %) and the bulk airflow Reynolds number (Rebulk = 300–1200) allows us to isolate key elements of the multiphase dynamics, providing the first laboratory observation of cluster-induced turbulence. Above a threshold Φ(V), the system exhibits intense fluctuations of concentration and velocity, as measured by high-speed imaging via a backlighting technique which returns optically depth-averaged fields. The space–time autocorrelations reveal dense and persistent mesoscale structures falling faster than the surrounding particles and trailing long wakes. These are shown to be the statistical footprints of visually observed clusters, mostly found in the vicinity of the walls. They are identified via a percolation analysis, tracked in time, and characterised in terms of size, shape, location and velocity. Larger clusters are denser, longer-lived and have greater descent velocity. At the present particle Stokes number, the threshold Φ(V) ∼ 0.5 % (largely independent from Rebulk) is consistent with the view that clusters appear when the typical interval between successive collisions is shorter than the particle response time.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Cambridge University Press
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/4.0/
dc.subject
fluidised beds
en_US
dc.subject
particle/fluid flow
en_US
dc.title
Experimental analysis of particle clustering in moderately dense gas-solid flow
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 4.0 International
dc.date.published
2021-12-20
ethz.journal.title
Journal of Fluid Mechanics
ethz.journal.volume
933
en_US
ethz.journal.abbreviated
J. Fluid Mech.
ethz.pages.start
A6
en_US
ethz.size
29 p.
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.publication.place
Cambridge
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02628 - Institut für Fluiddynamik / Institute of Fluid Dynamics::09709 - Coletti, Filippo / Coletti, Filippo
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02628 - Institut für Fluiddynamik / Institute of Fluid Dynamics::09709 - Coletti, Filippo / Coletti, Filippo
ethz.date.deposited
2021-12-25T03:53:04Z
ethz.source
WOS
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2022-03-02T10:30:49Z
ethz.rosetta.lastUpdated
2023-02-07T09:57:35Z
ethz.rosetta.versionExported
true
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