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Title: The gravity flow of bulk solids in bunkers
Author: Cousens, T. W.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1981
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This dissertation is mainly concerned with the experimental investigation of the flow of sand in a small aluminium alloy axi-symmetric bunker. The bunker consists of three cylindrical bin sections which can be fixed together and three alternative conical hoppers with circular outlets, with included apex angles of 400, 600 and 900 respectively, and a horizontal silo base whose circular outlet can be moved from a central position. Three types of sand were used as fill, the one used in the majority of tests being a Leighton Buzzard sand of particle size 0.65 mm to 1.10 mm. Radiographs were taken of the samples after small increments of flow and, from the measurement of lead markers in the fill, strains were computed. Any changes of fill density were also recorded. Wall stresses were measured using both existing and specially designed load cells in both intermittent and continuous tests. In mass-flow the wall stresses over most of the bunker on the discharge of a dense sample were shown to be much greater than the as-filled values. The deformation of the fill, after an initial phase, was stable and symmetric and could be divided into three zones; a rigid vertical block movement in the bin, a radial movement at constant volume in the lower hopper and in the upper hopper/lower bin a zone of volume increase. Rotation of the fill was also observed. The fill deformation in non mass-flow bunkers was also investigated and in these bunkers the wall stresses on discharge can also be much greater than the as-filled values and are affected by any eccentricity of the outlet. Radiography was performed, using a specially designed high speed shutter, while flow took place in a plane-strain bunker, and the results compared to those from intermittent tests. Centrifugal tests were performed on the axi-symmetric bunker and the wall stress data from laboratory floor model, centrifugal model and large scale prototype bunkers are compared and analysed. The experimental results of the mass-flow bunker are compared to three commonly used design methods.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available