Flow patterns and velocity fields in two-dimensional thin slice panel with flow-corrective insert

摘要

An experimental two-dimensional (2-D) thin slice panel for studying flow patterns of fine silica sand was designed and manufactured. As supplier of sand was not known at that time, flow properties of the silica sand were assessed without shear tests. A preliminary design of plane-flow hopper of the experimental 2-D panel was assumed to be close to the mass flow conditions. Sand was circulated in the experimental panel-to study the steady state flow. Tests of flow patterns suggested typical funnel-flow patterns with stagnant zones in the hopper and in the vertical part of the panel. Stagnant zones near the bottom of the hopper indicated insufficient width of the hopper outlet. Shear tests for estimation of flow properties of silica sand were carried out additionally and two methods of how to transform the funnel flow of sand to the mass flow were followed up; (a) existing 2-D panel was retrofitted with flow-corrective element, and (b) the width of outlet in existing experimental panel was widen into the size, calculated according to mass flow conditions. Both modifications were proven to be successful and the last-in first-out funnel flow was transformed into first-in first-out mass flow of sand. Velocities of individual tracer particles were measured during mass flow and velocity field was evaluated. Velocity profile of particles in the vicinity of flow-corrective insert was studied in detail.