A positron emission particle tracking investigation of the scaling law governing free surface flows in tumbling mills

Positron Emission Particle Tracking (PEPT) measurements are used to track the flow of d=5 mm glass beads within a rotating drum fitted with (and without) lifter bars and operated in the cascading and cataracting Froude regimes. After converting the Lagrangian trajectories of a representative radio‐l...

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Bibliographic Details
Published in:AIChE journal 2017-03, Vol.63 (3), p.903-913
Main Authors: Govender, Indresan, Richter, Max C., Mainza, Aubrey N., De Klerk, David N.
Format: Article
Language:English
Subjects:
Bars
Beads
bed depth
Cascading
cataracting
Chemical engineering
Ergodic processes
Fluid dynamics
Glass
Kinematics
Particle tracking
PEPT
Positron emission
repose
Scaling
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Summary:Positron Emission Particle Tracking (PEPT) measurements are used to track the flow of d=5 mm glass beads within a rotating drum fitted with (and without) lifter bars and operated in the cascading and cataracting Froude regimes. After converting the Lagrangian trajectories of a representative radio‐labeled glass bead (the tracer) into Eulerian fields under the ergodic assumption, the bed shape and kinematics are extracted for steady, fully developed flow conditions. Notwithstanding the azimuthal wall effects introduced by the lifter bars, we show a linear scaling 〈v〉∝h of the local flowing layer thickness (h) with local depth‐averaged velocity 〈v〉 and a constant average shear 〈γ̇〉∼0.6gd for direct measurements spanning the entire flowing layer (not just the central region), and high Froude regimes (cascading and cataracting) not previously investigated by scaling analysis in the literature. © 2016 American Institute of Chemical Engineers AIChE J, 63: 903–913, 2017
ISSN:0001-1541
1547-5905
DOI:10.1002/aic.15453