Experimental and theoretical investigations of silo music

This paper deals with strong dynamic effects connected with booming sound (called silo music) appearing during confined granular flow in silos. Novel experimental data have been gained through Electrical Capacitance Tomography (ECT) and an extraction of operational deflection shapes. A dynamic plane strain FE model of the granular material and oscillating wall was presented. The numerical results support the key role of dynamic coupling between silo wall oscillations and dynamics of the flowing material induced by a change of a flow direction at the transition zone between cylindrical and converging flow.

This paper deals with strong dynamic effects connected with booming sound (called silo music) appearing during confined granular flow in silos. Silo model experiments with dry cohesionless sand during gravitational outflow were performed with a cylindrical perspex model silo. During tests, wall accelerations and acoustic signals were recorded and operational deflection shapes of the silo structure were determined. In addition, solid concentration changes in the interior of sand during silo discharge were measured with electrical capacitance tomography sensors. A dynamic numerical model describing the phenomenon of the silo music was proposed. The experimental and theoretical results support a hypothesis that the dynamic solid-structure interaction originating at the transition zone between mass and funnel flow is the source of the silo music. Fig. 13: Time–frequency analysis of sound signal during silo discharge: a) time signal, b) short time Fourier transform, c) Fourier transform.Figure optionsDownload as PowerPoint slide