等径球颗粒群流动特征实验研究

Experimental study on flow characteristics of a stream of isodiametric sphere

为考察等径球颗粒流动特性以便正确地设计模型试验或简化离散元计算,进行了透明可视的二维(单层紧密排列)平底仓钢珠卸料实验、拟二维矩形料槽玻璃球卸料实验和三维半圆柱平底仓玻璃球卸料实验。结果表明:二维(单层)精确等径球颗粒床具有微晶格效应,因此流动是畸变的;半圆柱仓的三维流动不出现畸变;而第3方向取几个球厚度的拟二维流动也避免了微晶格效应和畸变。透明半圆柱平底仓的玻璃球卸料实验表明用它取代圆柱仓可以较好反映圆柱仓内颗粒流动规律。拟二维和半圆柱仓的简化对诸如球床式核反应堆堆芯内球流一类问题的模型实验和离散元模拟有实用价值。

To observe its flow features of a monosized spherical particle assembly, discharge experiments were carried out for three types of configurations. 1） two dimensional （2D） test of a single-layer packing of steel beads within a flat bottomed bin, 2） quasi-two dimensional （Q2D） test of a group of glass beads within a transparent rectangular bin, and 3） three dimensional （3D） test of a group of glass beads within a semi-cylindrical bin. The experimental results demonstrate that a 2D packing of isodiametric particles leads to distortional flow due to＇ microcrystallities＇, while the quasitwo dimensional arrangement （Q2D） with a thickness of several particle diameters and the three dimensional arrangement （3D） effectively avoid the distortion. The test with a transparent semi-cylindrical bin reveal the flow features of the real cylindrical bin well in a visualized way. So a Q2D or a semi-cylindrical simplified configuration is available for the model test of pebble flow in the core of a high temperature reactor or for similar discrete element simulation.