Study of jamming phenomenon for the high-temperature gas-cooled reactor

In this work, discrete numerical simulations are used to study the influence of container's geometry on probability of jamming J. The height of the pebble-bed h and the angle of the conical hopper α are among our varied parameters. By increasing the angle of the conical hopper, the probability of jamming remains almost constant till 40deg, then decreases when α≥60deg. Which is due to the influence of angle on the granular flow pattern and the fact that 60deg is almost the critical angle of repose of the flow. The results have shown that height has a crucial effect on jamming probability when h is smaller than a critical value, flow becomes more susceptible to jamming if we increase h, when h exceeds this critical value, J approaches unity. To understand the underlying physical mechanism, we computed the average total stress near the aperture during the discharge and measured it for various h. The trace of stress tensor tr[σ_ij] increases when h increases. Based on these observations, one can conclude that the stress has an imperative effect on the probability of jamming and deserves some leeway of research. (author)