The granular flow is one of the principal issues for the design of pebble bed reactors. Particularly, the clogging phenomenon raises an important issue for pebble bed reactors. In this paper, we conduct experiments and discrete particle simulation of two-dimensional discharge granular flow from a conical hopper, to study the effect of the particle bed height and hopper angle on the clogging phenomenon. In general, the clogging probability increases with height and starts to saturate when is larger than a critical value. The experimental result trends are supported by discrete simulations. To understand the underlying physical mechanism, we conduct discrete particle simulations for various values, focusing on the following parameters: the statistical averaging of the volume fraction, velocity, and contact pressure of particles near the aperture during the discharge. We found that, among all relevant variables, the contact pressure of particles is the main cause of the increasement of J when increases. An exponential law between the pebble bed and clogging probability J has been established based on these observations and Janssen model. As for hopper angle , J shows an almost constant behavior for any rise in followed by a sudden regression at . Surprisingly, the effect of is most obvious for intermediate values of , where we observe a sharp increasement of clogging probability. The same trend is observed in the two-dimensional discrete simulation results.

中文翻译：

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锥形漏斗的堵塞现象研究：颗粒床高度和漏斗角度的影响

颗粒流是卵石床反应器设计的主要问题之一。特别地，堵塞现象对于卵石床反应器提出了重要的问题。在本文中，我们对锥形料斗的二维排放颗粒流进行了实验和离散颗粒模拟，以研究颗粒床高度和料斗角度对堵塞现象的影响。通常，堵塞概率随高度增加而增大，并且在大于临界值时开始饱和。实验结果趋势得到离散仿真的支持。为了了解潜在的物理机制，我们对各种粒子进行了离散粒子模拟。值，着重于以下参数：在放电过程中孔附近颗粒的体积分数，速度和接触压力的统计平均值。我们发现，在所有相关变量中，粒子的接触压力是J增大时增大的主要原因。基于这些观察结果和扬森模型，已经建立了卵石床与堵塞概率J之间的指数规律。至于料斗角， J在上升时表现出几乎恒定的行为，随后在突然下降。。令人惊讶的是，对于的中间值，的影响最为明显，在该中间值处，观察到堵塞的可能性急剧增加。在二维离散仿真结果中观察到相同的趋势。