Particle flow patterns in a mechanically stirred two-dimensional cylindrical vessel

Malhotra, Karun; Mujumdar, Arun S.; Okazaki, Morio

doi:10.1016/0032-5910(90)80142-l

Cited by 28 publications

(9 citation statements)

References 16 publications

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“…These studies found the existence of particle recirculation patterns that move with the blade. Horizontal cylindrical mixer studies were performed by Malhotra et al,7–9 Laurent et al,10 Jones et al11 and Bridgwater et al12 The studies by Malhotra focused on two‐dimensional geometries and provide information on mixing kinetics and heat transfer coefficients for agitated dryers. Laurent et al10 found that flows in this geometry are periodic in nature, whereas Jones et al11 observed slower mixing when the fill level was increased.…”

Section: Introductionmentioning

confidence: 99%

Discrete element simulation of free flowing grains in a four‐bladed mixer

2009

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Numerical simulations of granular flow in a cylindrical vessel agitated by a fourblade impeller were performed using the discrete element method. Velocity, density, and stress profiles within the mixer displayed a periodic behavior with a fluctuation frequency equal to that of the blade rotation. Blade orientation was found to affect flow patterns and mixing kinetics. For an obtuse blade pitch orientation, a threedimensional recirculation zone develops in-front of the blade due to formation of heaps where the blades are present. This flow pattern promotes vertical and radial mixing. No recirculation zone was observed when the blade orientation was changed to an acute blade pitch. The system's frictional characteristics are shown to strongly influence the granular behavior within the mixer. At low friction coefficients, the 3-D recirculation in front of the obtuse blade is not present reducing convective mixing. Higher friction coefficients lead to an increase in granular temperature which is associated with an increase in diffusive mixing. Normal and shear stresses were found to vary with mixer height with maximum values near the bottom plate. Additionally, a strong dependence between the magnitude of the shear stresses and the friction coefficient of the particles was found. The stress tensor characteristics indicate that the granular flow in our simulations occurs in the quasi-static regime. At the same time, the averaged pressure was found to vary linearly with bed height and could be predicted by a simple hydrostatic approximation. V

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Section: Introductionmentioning

confidence: 99%

Discrete element simulation of free flowing grains in a four‐bladed mixer

2009

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“…Despite their extensive use, the flow of granular materials in agitated devices and the mechanisms by which particle motion is generated are still not fully understood. The majority of past studies have focused on dry granular materials 1–8. The more complicated and more frequently encountered case of agitated granular material in the presence of significant moisture has received less attention.…”

Section: Introductionmentioning

confidence: 99%

Characterization of granular flow of wet solids in a bladed mixer

Lekhal¹,

Conway²,

Glasser³

et al. 2006

AIChE Journal

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“…The mixing quality inside the rotary blender was a function of the rotational velocity, particle sizes, powder composition, flow-induced dilation of cohesive granular powders, and geometrical parameters of the mixer. Some studies have shown that the mixing quality in rotary drum blenders can be improved using internal blades or baffles (Jiang et al, 2011;Malhotra, Mujumdar, Imakoma, & Okazaki, 1988;Malhotra, Mujumdar, & Okazaki, 1990). Khakhar, McCarthy, Shinbrot, and Ottino (1997) analyzed the mixing of monodisperse particles in a rotating cylinder to explore the role of flow on the dynamics of the mixing process at rotational speeds ranging 5.0-20 rpm.…”

Section: Greek Lettersmentioning

confidence: 99%