Abstract
Few studies concern the prediction of the mass flow rate of a granular media discharged from a silo with a lateral orifice. However, this situation can have pratical interest considering a tank of granular material with a leak on its side. We studied experimentally the discharge of a vertical silo filled by spherical glass beads. We consider rectangular silos with a rectangular orifice. The impact of size, aspect ratio and position of the orifice and the effect of an additional air flow were studied. The measured parameters are the mass flow rate and the pressure along the silo, whereas the controlled parameters are the size of particles, and the flow rate of air. We identified two regimes of discharge according to the aspect ratio (of width to height) of the rectangular orifice. Increasing the air flow rate induces an increase of the granular media flow rate. Using a simple physical model to describe the grains and gas flow, we put in evidence the role played by the air pressure gradient at the outlet. Then we compared the experimental results with continuum Navier-Stokes simulations with the granular μ (I)-rheology. We showed that the continuum μ (I)-rheology describes well our discharge flow of granular media from silos, taking into account the effect of the position of the orifice as well as the coupling with the gas flow.
Highlights
We identified two regimes of discharge according to the aspect ratio of the rectangular orifice
We showed that the continuum μ(I)-rheology describes well our discharge flow of granular media from silos, taking into account the effect of the position of the orifice as well as the coupling with the gas flow
Among the wide spectrum of granular flows, we focused on a rather specific configuration: a relatively narrow elongated vertical tube, with an opening located on its lateral wall, filled with spherical glass beads, discharges its contents in a constant pressure environment, a gas flowing throughout the tube
Summary
Among the wide spectrum of granular flows, we focused on a rather specific configuration: a relatively narrow elongated vertical tube, with an opening located on its lateral wall, filled with spherical glass beads, discharges its contents in a constant pressure environment, a gas flowing throughout the tube. This case is of particular interest to understand conditions under which a set of nuclear solid fuel particles inside a typical PWR fuel rod, whose cladding would have failed under hypothetical accidental conditions, could disperse out of this rod. Using the Basilisk program, we solved the Euler-Euler two-phase mass and momentum balance equations using, (i) a simplified incompressible Darcy flow model for the gas phase and, (ii) an effective viscosity formulation to model the socalled μ(I) rheology with uniform compacity for the granular phase
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