Experimental study of discharge rate fluctuations in a silo with different hopper geometries

An experimental study of the flow of quartz particles with two different mean size was performed on a 3D silo at the scale of the laboratory. Two kinds of hopper geometry were used for the cylindrical silo: flat-bottomed and conical. The diameter of the outlet was varied. The dependence of the flow rate and its fluctuations on the silo geometry and outlet size was studied. The Beverloo equation was satisfied in all cases studied and the dependence of its parameters on the silo geometry and on the particle size was analyzed. Using a Fourier analysis, we found a characteristic frequency which varied with the outlet diameter and was virtually independent of the hopper geometry.

Experiments for the flow of quartz particles in a silo were conducted with different hopper geometries and varying the outlet size. Flow fluctuations in the mass discharge rate were observed and the fluctuation frequencies were found to increase with the outlet size.Figure optionsDownload as PowerPoint slideHighlights
► Beverloo's equation was always verified.
► Flow fluctuations presented a characteristic frequency for each outlet.
► The frequencies were related to accumulation and discharge cycles.
► The frequencies increased with the outlet size.
► Hopper geometry had virtually no effect on mass fluctuations.