Basic Research of a New System of Accurate Wet-Type Submicron Classification

本研究的目的是开发一种新的离心系统，该系统可以非常准确地分类悬浮在质量浓度非常低（例如1%）的液体（水）中的亚微米颗粒，通过应用在高度旋转的双壁容器内产生的几乎刚性旋转的通流。通过对该系统的流动和颗粒运动的分析，以及对二氧化硅颗粒的分类测量，研究了该系统的分类性能。因此，我们得到了以下主要结论。(1)在Rossby数（恒定值{通流量/（转速）^0）一定时，切割尺寸随Ekman数（旋转速率）的增加而减小。^5})，在一定的Ekman数（一定的旋转速率）下，随着Rossby数（通过流量）的减小而减小。ekman -数和rossby -数相关性的实验结果与理论结果基本一致。(2)当Rossby数一定时，锐度指数越接近完美分类的值，当Rossby数一定时，锐度指数越接近完美分类的值。Ekman-number- and rosssby -number-dependence的实验结果与理论结果在质量上是一致的，但在数量上却完全不一致。(3)实验得到的最高锐度指标值为1.35，与最近的精确离心分类器相当，尽管由于转速较低（小于1400rpm），切割尺寸比后者大。

The purpose of the present study is to develop a new centrifugal system which can very accurately classify even submicron particles suspended in a liquid (water) with a very low mass-concentration (ex. 1%) by applying an almost rigidly rotating through-flow produced within a highly rotating double-walled container. We have considered the classification performance of this new system by analysing the flow and the particle motion and by making the classification measurement of silica particles. Consequently, we have obtained the following main conclusions.(1) The cut size decreases with decreasing Ekman number (increasing rotation rate) at a constant Rossby number (constant value of {through-flow rate / (rotation rate) ^0. ^5}), and decreases with decreasing Rossby number (decreasing through-flow rate) at a constant Ekman number (constant rotation rate). The experimental result of the Ekman-number- and Rossby-number-dependence roughly agrees with the theoretical one.(2) The sharpness index approaches the value of the perfect classification with decreasing Ekman number at a constant Rossby number and with decreasing Rossby number at a constant Ekman number. The experimental result of the Ekman-number- and Rossby-number-dependence agrees with the theoretical one qualitatively, but does not quantitatively at all.(3) The highest sharpness index value of 1.35 obtained experimentally is comparable to that of the recent accurate centrifugal classifiers, although the cut size is larger than the latter because of lower rotation rates (less than 1400rpm).