Preliminary research on flow rate and free surface of the accelerator driven subcritical system gravity-driven dense granular-flow target

Abstract

A spallation target is one of the three core parts of the accelerator driven subcritical system (ADS), which has already been investigated for decades. Recently, a gravity-driven Dense Granular-flow Target (DGT) is proposed, which consists of a cylindrical hopper and an internal coaxial cylindrical beam pipe. The research on the flow rate and free surface are important for the design of the target whether in Heavy Liquid Metal (HLM) targets or the DGT. In this paper, the relations of flow rate and the geometry of the DGT are investigated. Simulations based on the discrete element method (DEM) implementing on Graphics Processing Units (GPUs) and experiments are both performed. It is found that the existence of an internal pipe doesn’t influence the flow rate when the distance from the bottom of the pipe to orifice is large enough even in a larger system. Meanwhile, snapshots of the free surface formed just below the beam pipe are given. It is observed that the free surface is stable over time. The entire research is meaningful for the design of DGT.

Collisional regime during the discharge of a 2D silo

“…For this study the particles are identical with their parameters given by Y = 5 The parameter values selected give rise to results that are consistent other computational and experimental studies in the literature (see, e.g., [2,4,5,9,14,23,24,26,32,41,43]). The value chosen for the Young's modulus ensures that the particles are stiff enough to display a realistic granular behaviour, while keeping the integration time step δt at manageable values.…”

“…The discharge of a silo by gravity has been during years a favourite process to explore the dynamics of granular materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. These media consist of macroscopic particles interacting by frictional contact forces, giving rise to a plethora of novel behaviours studied by engineers and physicists alike [16][17][18][19][20][21][22][23][24][25][26].…”

Investigating the hard X-ray production via proton spallation on different materials to detect elements

“…The consistency between the simulation and experimental results was estimated at 100% (Table 1). The characteristics of gamma at 6.13 MeV energy each were experimentally measured by bombarding 19 F and 16 O nuclei with 113 MeV protons [51,52]. The simulation results estimated the values of 6.13 MeV and 6.14 MeV for 16 O and 19 F, respectively.…”

“…The detection of elements was achieved through gamma spectra resulting from the spallation of a target under neutron irradiation. The neutron beam production was accomplished through proton beam irradiation of the spallation target [19]. In another study, Chiera et al [20] measured the gamma rays produced by proton and neutron spallation of various targets for element detection purposes.…”

Influence of an inserted bar on the flow regimes in the hopper*

“…Under the insert, a free surface forms during the discharging, which was studied in Li et al's work. [23] The simulations showed that the free surface has a steady shape which could be fitted to be a paraboloid. Recently, Wojcik et al performed a large scale experiment of hopper flow with inserts and found that the recommendations based on previous small scale studies are no longer a good solution in large scale tests.…”