皂膜解吸Marangoni对流观察及分析

Observation and analysis of Marangoni convection induced by desorption in soap film

利用竖直流动皂膜装置,使用纹影光学方法观察了由于丙酮从皂液中解吸,在微米级厚度皂膜上出现的滚筒状Marangoni对流结构;通过建立皂膜传质数学模型及求解,分析了丙酮从皂膜解吸过程中浓度及表面张力的变化。结果表明:由于微米级的皂膜厚度,在皂膜平面法向方向皂膜内皂液丙酮浓度变化很小,但浓度梯度较大,对应的表面张力梯度较大,此较大表面张力梯度是丙酮从皂膜解吸过程中出现Marangoni对流的主要成因。

By means of the falling soap film tunnel and the Schlieren optical method,the orderly roll Marangoni convection patterns along the surface of the falling soap film with 10^-6 m order thickness were observed directly during the acetone desorption from the falling soap liquid.The acetone desorption model from the falling soap film was established and solved theoretically in order to analyze the variation of the concentration and the surface tension.The results show that the variation of the acetone concentration vertical to the falling direction within the thin film is very small,but the gradients of both the acetone concentration and surface tension are large.So the big tension gradient is the main reason for the occurrence of the Marangoni roll convection in acetone desorption from soap film.