Motion and stress intensity of grinding beads in a stirred media mill. Part 1: Energy density distribution and motion of single grinding beads
Motion and stress intensity of grinding beads in a stirred media mill. Part 1: Energy density distribution and motion of single grinding beads
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搅拌介质磨机中研磨珠的运动和应力强度。
DOI：
10.1016/0032-5910(95)03038-7
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发表时间：
1996
影响因子：
5.2
通讯作者：
J. Schwedes
中科院分区：
文献类型：
--
作者：
L. Blecher;A. Kwade;J. Schwedes
本文对搅拌介质磨机内的流场、比能分布和单个磨粒的运动进行了数值计算。计算是基于稳态层流搅拌的牛顿流体没有研磨介质。搅拌流体的流场产生比能的特征分布。存在以高能量密度为特征的两个区域。在这些区域中，局部比能大于平均比能，该平均比能通过将在研磨室中耗散的能量的总量除以研磨室的净体积而获得。一个区域围绕搅拌盘延伸，而另一个区域位于研磨室壁处。这两个区域的体积仅为净研磨室体积的约10%。大约90%的能量输入都消耗在那里。暴露于先前确定的流动模式的单个研磨珠倾向于在研磨室中遵循几乎静止的单个轨迹。轨迹的位置取决于珠与流体密度的比率、珠与盘半径的比率以及描述搅拌介质研磨机的操作条件的雷诺数。这些参数的影响可以通过所谓的运动指数来描述。当运动指数达到某一临界值时，单个微珠基本上跟随流体流动并通过两个高能量密度区。
Numerical calculations concerning the flow field, the distribution of the specific energy and the motion of single grinding beads in the grinding chamber of a stirred media mill have been carried out. The calculations are based on steady-state laminar stirring of a Newtonian fluid without grinding media. The flow field of the stirred fluid generates a characteristic distribution of the specific energy. Two zones characterized by a high energy density exist. In these zones the local specific energy is larger than the mean specific energy which is obtained by dividing the total amount of energy dissipated in the grinding chamber by the net volume of the grinding chamber. One zone extends around the stirrer disc whereas the other is located at the grinding chamber wall. The vilume of these two zones is only about 10% of the net grinding chamber volume. Approximately 90% of the entire energy input is dissipated there. Single grinding beads that are exposed to a previously determined flow pattern tend to follow an almost stationary individual trajectory in the grinding chamber. The position of the trajectory depends on the ratio of bead-to-fluid density, the ratio of bead-to-disc radius and the Reynolds number which describes the operating conditions of the stirred media mill. The influence of these parameters can be described by the so-called motion index. Up to a critical value of the motion index, the single bead follows basically the fluid flow and passes through the two zones of high energy density.