Studies on granular materials. III. Stress distribution in a granular material mixed by a mechanical impeller

Novosád, Jan

doi:10.1135/cccc19642702

Cited by 6 publications

(3 citation statements)

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“…We have looked for a possible support to this explanation in the literature, but such phenomena seems to be not very well documented, even in the rather well developed literature devoted to the mechanics of powder in shear granulators. Novosad showed that the shear plane can extend further the tip of the blade toward the external wall, but does not quantify the stress effect. In their experiments on the effect of the bottom wall to the kinematics and to the mechanics of the powder shear induced by the movement of a blade, Bagster and Bridgwater did find some limited effect.…”

Section: Resultsmentioning

confidence: 99%

On the use of a powder rheometer to characterize the powder flowability at low consolidation with torque resistances

et al. 2017

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The Anton Paar Powder Cell was used to measure the torque necessary to rotate an impeller in beds of glass beads, sand and alumina powders aerated between no aeration to the minimum for fluidization. Measured torque values depend on the material tested, on the air flow rate applied, on the impeller depth and on the height of the impeller blade. The effect of the impeller depth is linear for low impeller depth and is less than linear at high depth values. A model was developed for the interpretation of the experimental results based on the idea that the material is shearing on the surface described by the impeller rotation. The model allows to estimate an effectiveness of the impeller in the torque determination and also to predict the torque for the impeller at the at deepest positions at which the wall effects have to be considered

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Section: Resultsmentioning

confidence: 99%

On the use of a powder rheometer to characterize the powder flowability at low consolidation with torque resistances

et al. 2017

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“…The dependence in the former section can be expressed approximately as (2) or after rearrangement (3) where Kl = 0·375 . (4) Vol. 30 " (1965) or Novosad, Standart: In the latter section the relation can be approximated as …”

Section: Empirical Correlation Of the Measured Valuesmentioning

confidence: 98%

“…Their a~gles of internal and external friction were measured on a rotational shear apparatus 5 . The function cP for these materials is also given in the table for the angle of external friction between the granular material and steel. This quantity, derived in the previous paper 4 gives the magnitude of the stress on the blade at unit depth in a granular material of unit specific bulk weight (see below).…”

Section: Apparatusmentioning

confidence: 99%

Studies on granular materials. IV. Calculation of the shaft torque for mixing granular materials

Novosád¹,

Standart²

1965

Collect. Czech. Chem. Commun.

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The shaft torque of a simple paddle mixer was measured when mixing granular materials in a cylindrical vessel in dependence on the material properties and certain geometrical parameters. The results were correlated semi-empirically and relations were found for determining the critical depth and critical moment of the granular bed. A dimensionless equation was found by dimensional analysis for determining the shaft torque of the mixer for subcritical depths of bed and by extrapolation to blades of infinitely large diameter the correctness of the derivation was shown.The shaft torque required in mixing granular materials is important not only in designing mixing equipment but also yields information about the force relations in the granular material. There are only a few articles in the literature dealing with this problem: Weighardt\ Iiyama and Aoki2, Lastovcev and Chvalnov 3 .The main contribution of this paper consists in using the theoretically derived value of the stress on the mixer blade in deriving . the semi-empirical correlations. This stress was obtained from the shapes of the slip surfaces in the vicinity of the blade 4 . Further the interesting concept of the critical depth of the granular bed and the corresponding critical torque are introduced. Experimental ApparatusFor the experimental work we modified a drill press (Fig. 1) to serve as the basis of the mixing unit. The mixer shaft 1 was driven by an el-motor 9. The system of V-belt transmissions enabled us to change the shaft rpm's over the range 1 to 400 rpm. The mixing shaft torque was measured indirectly by measuring the torque exerted on the mixing vessel 1 0 which was mounted on the rotable shaft 3. The principle of measuring the torque by a balance is clear from the figure. The

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The flow of granular material over a moving blade

Bagster

Bridgwater

1969

Powder Technology

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Studies on granular materials. III. Stress distribution in a granular material mixed by a mechanical impeller

Cited by 6 publications

References 0 publications

On the use of a powder rheometer to characterize the powder flowability at low consolidation with torque resistances

On the use of a powder rheometer to characterize the powder flowability at low consolidation with torque resistances

Studies on granular materials. IV. Calculation of the shaft torque for mixing granular materials

The flow of granular material over a moving blade

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