Characterization and prediction of dripping of liquid films flowing underneath planar surfaces and on tilted cylinders

在能源和过程工程中的许多应用中，下降液膜具有技术相关性。相关文献对倾斜或垂直壁上不同表面几何形状的膜演化和膜传输特性进行了全面的概述。倾斜平面下的膜的实验和数值数据非常稀少，尽管它们在例如化学工程中的涂层问题或规整填料中具有重要意义。在这些应用中，防止滴漏以确保均匀涂层或促进滴滴以增加液/气界面面积是非常重要的。由于表面下液膜滴落的非线性特性，目前还不能用解析的方法来描述液滴的起滴过程和滴落质量流的定量关系。在该项目中，通过全分辨数值模拟、低维模拟和实验研究，分析了液膜在基本表面几何形状下的滴落过程。其目的是为滴水的开始提供物理激励的相关性，并量化滴水质量流和特定表面积，以便能够有针对性地设计相应的工艺。

Falling liquid films are of technical relevance in a multitude of applications in energy and process engineering. The relevant literature offers a comprehensive overview of film evolution and film transfer properties on inclined or vertical walls and differing surface geometries. Experimental and numerical data of films underneath an inclined plane are very scarce, despite their importance in e.g. coating problems or structured packings in chemical engineering. In these applications, the prevention of dripping to ensure homogeneous coatings or the promotion of dripping to increase liquid/gas interface areas is of high interest. Due to the non-linear character of dripping from films beneath surfaces, an analytical approach to the problem is difficult and correlations for the onset of dripping and a quantification of dripping mass flows are not available at present.Within the proposed project, the dripping regime in films flowing beneath basic surface geometries is analyzed through fully resolved numerical simulation, low-dimensional modeling and experimental investigations. The aim is to provide physically motivated correlations for the onset of dripping and to quantify dripping mass flows and specific surface areas to enable a targeted design of respective processes.