The sensitivity of silo flow and wall stresses to filling method

The pattern of solids flow during discharge of a silo and the pressures against the silo wall are commonly assumed to depend only on the measurable properties of the solid, including its interaction with the silo wall. A small number of previous studies have noted that the method of filling the silo may affect the flow pattern, generally altering it from mass to mixed flow. It has been suggested that this change may be caused by altered mechanical properties of the solid. However, the significance of the filling method for the practical design of silos has rarely been considered. In this experimental study, barley and plastic pellets were tested in a pilot scale aluminium silo with a flat bottom. The paper outlines the results of the experiments, in which flow pattern observations were made from the top surface, and wall stresses were measured using strain gauges. The filling process is seen to have a marked effect on the flow pattern and wall stresses found for plastic pellets, but very little effect on those for barley. The implications for silo design are discussed briefly.