Non-contact transport of sub-micron particles in pipes

本工作的目的是开发一种亚微米颗粒在管道中的非接触输运方法。首先，设计了一种利用分离和电斥力引起的流动收缩的方法。该方法采用部分管壁作为电极。流动分离是由管内的喷嘴产生的。数值计算表明这种方法是可行的，但实际上流体湍流使颗粒无法与管壁保持非接触状态。此外，电力不能有效地用于这一目的。因此，在第二阶段的工作中，尝试了另一种使用同心圆柱体的方法。但除了输运问题外，还研究了粒子与壁面非接触状态的可能性。尝试了一种使用同心圆柱体的方法。内筒旋转，外筒静止。壁和粒子是带电的。由于离心力和电斥力的作用，希望粒子与壁面保持非接触状态。在这种方法中，可以通过减小两壁之间的距离来产生强大的斥力。在实验中，系统地改变了内缸的转数和电压差。发现了电荷和离心力的影响，但目前的方法仍不能达到真正的非接触状态。

The purpose of the present work is to develop a method of non-contact transport of sub-micron particles in pipelines.At first, a method using flow contraction due to separation and electric repulsion force was planned. In this method, a part of pipe wall was used as an electrode. The flow separation was produced by a nozzle in the pipe. Numerical calculations showed that this method is possible but actually fluid turbulence prevented particles from keeping non-contact state with the pipe wall. Also, the electric force can not be efficiently used for the purpose.Therefore, in the second phase of the work, another method using concentric cylinders was attempted. But apart from the problem of transport, the possibility of the non-contact state of particles with walls was investigated. A method using concentric cylinders was attempted. The inner cylinder rotates and the outer one is stationary. Walls and particles were charged. Due to the centrifugal force and electric repulsion force, it is hoped that particles keep non-contact condition with the walls. In this method, the strong repulsion force can be produced by making the distance between two walls small. In the experiment, the rotating number of the inner cylinder and voltage difference were changed systematically. The effect of electric charge and centrifugal force was found but the present method was still not satisfactory enough to achieve the true non-contact state.