Review on testers for measuring flow properties of bulk solids

Schwedes, Jörg

doi:10.1007/s10035-002-0124-4

Cited by 306 publications

(201 citation statements)

References 2 publications

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“…In mechanical and chemical engineering, e.g., for the design of silos, the Jenike procedure [3,13] is based on the knowledge of several yield loci, including also yield loci under time-consolidation, which tend to show greater shear stresses and cohesion than for instantaneous measurements. The flow-function of Jenikes procedure is based on the unconfined yield stress, σ c , which can be obtained from the Mohr circle that goes through zero confining stress and is tangent to the yield locus.…”

Section: Practical Examplesmentioning

confidence: 99%

The critical-state yield stress (termination locus) of adhesive powders from a single numerical experiment

Luding¹,

Alonso‐Marroquín

2011

Granular Matter

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Dry granular materials in a split-bottom ring shear cell geometry show wide shear bands under slow, quasistatic, large deformation. This system is studied in the presence of contact adhesion, using the discrete element method (DEM). Several continuum fields like the density, the deformation gradient and the stress tensor are computed locally and are analyzed with the goal to formulate objective constitutive relations for the flow behavior of cohesive powders. From a single simulation only, by applying time-and (local) space-averaging, and focusing on the regions of the system that experienced considerable deformations, the critical-state yield stress (termination locus) can be obtained. It is close to linear, for non-cohesive granular materials, and nonlinear with peculiar pressure dependence, for adhesive powdersdue to the nonlinear dependence of the contact adhesion on the confining forces. The contact model is simplified and possibly will need refinements and additional effects in order to resemble realistic powders. However, the promising method of how to obtain a critical-state yield stress from a single numerical test of one material is generally applicable and waits for calibration and validation.

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Section: Practical Examplesmentioning

confidence: 99%

The critical-state yield stress (termination locus) of adhesive powders from a single numerical experiment

Luding¹,

Alonso‐Marroquín

2011

Granular Matter

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“…At low shear strain rates powders naturally form dense structures, where the shear resistance is driven by friction and mechanical interlocking. Techniques have long been established for characterising powder flowability for the initiation of flow under quasi-static conditions, using shear cells; based on which theories have been developed for hopper design (Carson, 2015;Jenike, 1961;Schwedes, 2003). There are extensive works reported in the literature on arching; for example cohesive arching has been analysed by Enstad (1975), and more recently mechanical arching by Tang and Behringer (2011).…”

Section: Introductionmentioning

confidence: 99%

Analysis of powder rheometry of FT4: Effect of air flow

Nan

Ghadiri

Wang

2017

Chemical Engineering Science

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Understanding of particle flow behaviour as a function of strain rate is of great interest in many items of equipment of industrial processes, such as screw conveyors, impeller mixers, and feeders, etc. The traditional commercial instruments for bulk powder flow characterisation, such as shear cells, operate at low shear strain rates, and are not representative of unit operations under dynamic conditions. In recent years, the FT4 powder rheometer of Freeman Technology has emerged as a widely used technique for characterising particle flow under dynamic conditions of shear strain rate; yet little is known about its underlying powder mechanics. We analyse the effect of gas flow on the flow behaviour of cohesionless particles in FT4 both experimentally and by numerical simulations using the combined discrete element method (DEM) and computational fluid dynamics (CFD). The results show that the effect of gas flow on the flow energy could be described by the resultant fluid-induced drag on the particles above the blade position as the impeller penetrates the bed. The strain rate in front of the blade is mainly determined by the impeller tip speed, and is not sensitive to the gas flow and particle size. The flow energy correlates well with the shear stress in front of the blade. They both increase with the strain rate and are significantly reduced by the upward gas flow.

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“…Carr's flowability index obtained with the Powder Characteristics Tester (for example; Masuda, et al, 1975;Yokoyama, 1997), flow factor measured with the Jenike Shear Tester (Yokoyama, 1997;Schwedes, 2003) and flowability determined with the Hall-flowmeter subjected to vibration (Staffa, et al, 1977). The Hall-flowmeter might be useful since the powder is actually flowing during the test; however, the evaluation factor is only the time required for a 50 g sample to flow through a standardized funnel.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Flowability of Composite Particles and Powder Mixtures by a Vibrating Capillary Method

Jiang

Matsusaka

Masuda

et al. 2006

J. Chem. Eng. Japan

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Flowability of micrometer-sized particles treated with nanometer-sized particles has been studied by a vibrating capillary method. Two different types of treatments, i.e. dry particle coating based on the mechanofusion and simple mixing through shaking manually, were adopted to prepare composite particles and powder mixtures, respectively. The micrometer-sized core particle was polymethylmethacrylate (PMMA), and the coating nano-particles were TiO 2 , Al 2 O 3 , or SiO 2 . Surface morphology of the treated particles was * To whom correspondence should be addressed. E-mail: matsu@cheme.kyoto-u.ac.jp 2 analyzed by digital processing of SEM photographs, and flow behavior of powders in the vibrating capillary tube was studied with particular attention to the effects of the kind of nano-particles, its concentration, and the treatment method. Two factors were introduced to evaluate the flowability; one is the critical amplitude of vibration making the powder flow, and the other is the mass flow rate as a function of the vibration amplitude. The experimental results show that the mechanofusion treatment gave a remarkable improvement in the powder flowability evaluated by the two factors mentioned above. The general tendency of the improvement can be explained by the projected-area ratio defined as the ratio of the total projected-area of nano-particles adhering to core-particle surface and the projected-area of the core-particle itself.

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Review on testers for measuring flow properties of bulk solids

Cited by 306 publications

References 2 publications

The critical-state yield stress (termination locus) of adhesive powders from a single numerical experiment

The critical-state yield stress (termination locus) of adhesive powders from a single numerical experiment

Analysis of powder rheometry of FT4: Effect of air flow

Evaluation of Flowability of Composite Particles and Powder Mixtures by a Vibrating Capillary Method

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