Correlation between the flow pattern and wall pressures in a full scale experimental silo

Although it has been known for several decades that the pattern of solid flow in a silo has a strong influence on the pressures exerted on the silo walls, no full-scale test has ever been able to measure both the flow pattern and the wall pressures together. This paper describes simultaneous measurements of both the flow pattern and the wall pressures in a full scale silo storing approximately 250 tonnes of iron ore pellets. About 300 radio frequency tags were seeded into the stored granular solid at predefined locations to measure residence times, and over 300 strain gauges were used to concurrently measure strains on the silo walls. The flow pattern was determined from the residence time measurements and the wall pressure distribution was inferred from the strain gauge measurements. The study has produced a clear definition of the pressure regime at full scale under eccentric discharge with a pipe flow against the silo wall. A strong correlation between the flow channel and the discharge pressure distribution, which was always previously assumed, is here demonstrated from the observations.