搅拌反应釜中微观混和问题的研究——(Ⅰ)—频闪高速显微摄影法研究微观混和过程

STUDIES ON MICROMIXING IN STIRRED TANK REACTORS Ⅰ.HIGH SPEED STROBOSCOPIC MICROSCOPIC PHOTOGRAPHY AND ITS APPLICATION

本文介绍了作者首次开发成功的、用于观察亚微观及微观混和过程的微流元团变形历程的新型方法——高速频闪显微摄影法。作者用此方法首次拍摄到了无化学反应与伴有化学反应时的湍流场中亚微观及微观混和过程中微流元团的照片,对微观混和过程有了感性认识。并提出此过程由以下三个过程组成:(i)湍流涡旋的产生、死亡和再生,使得大涡团分裂成小涡团;(ii)小涡团内的无规则复杂的层片状伸长变形及(iii)分子扩散过程。所得到的这些结果为微观混和问题的进一步深入研究提供了重要的感性认识和物理基础。

It is the first time that a new technique,the High Speed Stroboscopic Micro- scopic Photography which is developed and sucessfully used in our laboratory for the observation of the deformation history of fluid element during submicro-and micromixing processes,is here reported.Pictures of these microfluid elements during mixing in turbulent field with or without chemical reaction were taken. Beside perceptual knowledges,we also found that the micromixing process is composed of three successive stages:(1)the death and rebirth of turbulent vortices to get the large vortices splitting into smaller ones,(2)stochastic laminar elongation in the small vortices and(3)the diffusion process.The results obtained provide important intuitions and physical basis for the study of micromixing processes.