Abstract: The Schlieren technique with double optical path was established.With the new technique,the natural convection of CO₂ absorption into and desorption from chlorobenzene in a quiescent cell was visualized from horizontal and vertical directions simultaneously.During the absorption process,the convection does not appear,and only dark stripes appear from the vertical direction.In the desorption process,evident convection emerges in both horizontal and vertical directions.At the beginning of the desorption process,the stratification appears in the vertical direction,and it is destroyed with the convection becoming more and more intense.The characteristic velocity of the horizontal convection is larger than that of normal one,then the convection appears in the horizontal direction.The convection structure tends to move to the center of the cell because of the heat effect from the mass transfer.The results show that the dual-path Schlieren technique can be used to observe tridimensional convections easily and simultaneously,based on which the mass transfer can be studied more deeply.

Key words: dual-path Schlieren system, interfacial turbulence, mass transfer, Marangoni convection, Rayleigh-Bénard convection

摘要： 建立了双光路纹影仪实验系统,并利用双光路纹影仪,同时从垂直和平行于界面两个方向对氯苯吸收、解吸CO₂的传质对流结构进行了观察,发现在氯苯吸收CO₂时,没有明显的对流结构,只是在垂直界面的纹影图像中观察到逐渐变粗的暗条纹。在氯苯解吸CO₂时,在垂直和平行于界面两个方向都观察到了明显的对流结构,在垂直界面的纹影图像中开始时出现分层现象,随着解吸的进行,对流加剧,分层现象被破坏;平行界面方向的对流结构发展较快,优先在平行界面的纹影图像中观察到明显的对流结构。由于传质的热效应,两个方向的对流结构都有向中心运动的趋势。实验表明,双光路纹影仪实验系统能观察界面传质对流过程的三维变化,可深化对界面传质对流过程的认识。

关键词: 双光路纹影系统, 界面湍动, 质量传递, Marangoni对流, Rayleigh-Bénard对流