Discharge flow of a granular media from a silo: effect of the packing fraction and of the hopper angle

Mebirika Benyamine,Pascale Aussillous,Blanche Dalloz-Dubrujeaud,F Radjai,S Nezamabadi,S Luding,J.Y Delenne

doi:10.1051/epjconf/201714003043

Abstract

Silos are widely used in the industry. While empirical predictions of the flow rate, based on scaling laws, have existed for more than a century (Hagen 1852, translated in [1] - Beverloo et al. [2]), recent advances have be made on the understanding of the control parameters of the flow. In particular, using continuous modeling together with a mu(I) granular rheology seem to be successful in predicting the flow rate for large numbers of beads at the aperture (Staron et al.[3], [4]). Moreover Janda et al.[5] have shown that the packing fraction at the outlet plays an important role when the number of beads at the apeture decreases.Based on these considerations, we have studied experimentally the discharge flow of a granular media from a rectangular silo. We have varied two main parameters: the angle of the hopper, and the bulk packing fraction of the granular material by using bidisperse mixtures. We propose a simple physical model to describe the effect of these parameters, considering a continuous granular media with a dilatancy law at the outlet. This model predicts well the dependance of the flow rate on the hopper angle as well as the dependance of the flow rate on the fine mass fraction of a bidisperse mixture.

Highlights

The prediction of the mass flow rate of a granular media discharged from a silo has been widely studied because of its practical interest in several industries, for example to ensure reproducible and efficient handling in plant operations
Using continuous modeling together with a mu(I) granular rheology seem to be successful in predicting the flow rate for large numbers of beads at the aperture (Staron et al.[3], [4])
In this paper we investigate the influence of the discharge angle of the hopper, and the bulk packing fraction of the granular material

Summary

Introduction

The prediction of the mass flow rate of a granular media discharged from a silo has been widely studied because of its practical interest in several industries, for example to ensure reproducible and efficient handling in plant operations (food, mining, ceramic, paint, pharmaceutical... industries). The prediction of the mass flow rate of a granular media discharged from a silo has been widely studied because of its practical interest in several industries, for example to ensure reproducible and efficient handling in plant operations More recent works proposed a continuous modeling with a mu(I) granular rheology which gives good results for a large amount of beads at the aperture [3], [4]. Our results are interpreted through a physical and analytical model (based on the work of Janda et al.[5]) considering a modification of the density close to the outlet due to the flow

Experimental methods

Results and discussion

Bidisperse mixtures

Discharge angle

Conclusion