Abstract
We present an experimental study on the discharge flow of a granular media from a rectangular silo with a cylindrical obstacle placed above the outlet. As described in the literature, the presence of an obstacle decreases the flow rate, but the characteristic lengths to be chosen in the flow rate law are not known. To predict the flow rate we vary the obstacle diameter and vertical position, the outlet size and the particle diameter. However due to the large number of parameters we find that the characteristic length which controls the flow rate cannot be thoroughly defined. To model the effect of an obstacle on the flow rate we design a new configuration with an orifice at the corner of the silo. We study the two extreme cases (a bottom orifice at the wall and a lateral orifice) and we show that for the corner all the data are in between these two cases.
Highlights
Confined geometries like silos are widely used for the processing of granular and powder materials which are important in many engineering applications, but the discharge flow of granular matter in silos remains an open subject of study.A very famous problem in silos is jamming
We have experimentally studied the discharge flow of ceramic beads from a rectangular silo in the presence of a cylindrical obstacle
We have shown that for an altitude higher than the orifice length the obstacle does not infer on the flow rate, while when situated in the zone of acceleration above the outlet the presence of the obstacle decreases significantly the flow rate
Summary
Confined geometries like silos are widely used for the processing of granular and powder materials which are important in many engineering applications, but the discharge flow of granular matter in silos remains an open subject of study. Zhou et al [16] have shown experimentally and using continuous simulation with a frictional rheology that if the outlet is located at a lateral position the silo thickness plays a role due to the confinement of the geometry. They have shown that the parietal friction tends to rotate the streamlines to align them toward the gravity with an angle at the outlet sinθ0 ∝ (1 + γD/W )−1/2, whereas the norm of the velocity scales with the aperture. To simplify the problem a new experimental configuration is proposed in Section 4 where the orifice is placed at the corner of silo without obstacle in order to find out which parameters are relevant to describe the flow rate
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