Proposta de uma nova metodologia para a determinação da transição catarateamento-centrifugação utilizando partículas esféricas e não-esféricas em um tambor rotatório via técnicas de CFD
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2020-02-18
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Universidade Federal de Goiás
Resumo
Rotary drums are widely utilized in several industrial processes, such as drying, mixing,
milling, granulation, among others. The widespread frequent use of rotary drums is due to
their simple design and their capability to handle materials characterized by broad size
distributions with significant differences in their physical properties. The granular flow inside
rotary drums can be classified in different forms: sliding, slumping, rolling, cascading,
cataracting, and centrifuging regimes. This classification depends on the drum operating
conditions and the physical properties of the particulate material envolved in the granular
flow. There are have been no reposts in the literature that presents a precise methodology for
cataracting-centrifuging transition identification in rotary drums. This identification is carried
out exclusively by visual and subjective way. In this context, the present work aims the
proposition of a methodology for the cataracting-centrifuging transition identification, for
different particle shapes, using the Multiphase Granular Eulerian Model (MGEM), implemented
by CFD simulations. When compared to the Lagrangian model (DEM), the mainly difficult
associated with Eulerian model is the particle shape representation, since the solid phase is
treated as continuous in CFD simulations. The particle shape for non-spherical particles was
indirectly represented in the MGEM using the critical solid fraction (αsc), a parameter
associated with the Schaeffer’s frictional model. The present work is also dedicated to
overcoming this difficulty. The drum length effect on the cataracting-centrifuging transition
was also analyzed. Using the methodology herein proposed was verified that the particle
shape and the drum length influence the cataracting-centrifuging transition behavior. For nonspherical
particles was required lower values of rotation speed to reach the centrifuging
regime condition when compared with spherical particles. It was verified that the lower the
drum length, the higher the facility associated with the transition for centrifuging regime for
both particle shapes.
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Citação
Benedito, W. M. Proposta de uma nova metodologia para a determinação da transição catarateamento-centrifugação utilizando partículas esféricas e não-esféricas em um tambor rotatório via técnicas de CFD. 2020. 54 f. Dissertação (Mestrado em Engenharia Química) - Universidade Federal de Goiás, Goiânia, 2020.