Granular discharge and clogging for tilted hoppers

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Original entry by Sagar Bhandari, APPHY 225 Fall 2010


Granular discharge and clogging for tilted hoppers, Hannah G. Sheldon and D. J. Durian, Granular Matter,Volume 12, Number 6, 579-585


tilted hoppers, glass beads, granular discharge, clogging


In this paper, the authors study the behavior of spherical glass beads when passed through a small hole and the diameter and tilt angle - dependence of the flow rate. They also study the condition for zero flux /clogging in terms of hole diameter and tilt angle.

The authors use granular medium consisting of spherical glass beads, with two different diameters: d = 0.30 ± 0.05 mm and d = 0.9 ± 0.1 mm. Both have bulk density of 1.53±0.01 g/cubic cm. and draining angle of repose of 24 degrees. As a medium to pass the bead through, two different containers are used - steel can and aluminum square tube. Holes are drilled in three different locations: in the bottom at center, in the bottom at 2 cm from the side, and in the side at 2 cm above the bottom. In their experiments, the containers are grounded to prevent electrostatic charging, while the tilt angle of the plane of the hole away from horizontal is measured with a plumb bob and protractor. Figure 1 shows the sketch of four different tilt angles.

Figure 1:

Sagar wiki7 image1.jpg

The discharge rate is measured by weighing the material collected during a timed interval. Initially, the hole is covered with a piece of paper and the granular medium is poured into the container. After filling the container,the covering is removed and flow allowed to proceed for a several seconds or more. Next a beaker is used to collect the discharge stream while simultaneously starting a timer which is then removed while simultaneously stopping the timer.

Figure 2:

Sagar wiki7 image2.jpg