The stability of material bridges in aerated silos

Abstract When air is injected through the aerating bottom of a silo for bulk materials, some of the air excapes through the outlet. This places a stress on stable material bridges. The additional stresses at the abutments of the bridge, caused by the air flow, are calculated for plane and radially symmetrical bin geometries. By superimposing the result on the stress on the abutment when the material is not aerated and flows under gravity, the volumetric air flow and the corresponding excess pressure needed to destroy the material bridge are computed. Some of the factors involved in the calculations were determined by electrical analogue models, and the flow pattern of the air is illustrated.