Three Dimensional Hydrodynamics of Liquid Falling Film Flow Over Inclined Micro Topography

Structured packings used in a wide range of industrial engineering intensify the mass transfer between the gas and liquid phase up to 80% compared to the unstructured surface. Usually structured packings consist of microstructures in the range of less than one millimeter. It is known that these structures promote the stability and the spreading of the gravitational driven liquid film flow.
The phenomenon of mass transfer amplification induced by the micro structured topography is investigated by means of the three dimensional velocity field in the liquid film flow. Therefore a three dimensional stereoscopic micro particle image velocimetry system is adapted. The velocity field, film thickness profile and interfacial shape are measured for different industrial applied micro-structures.
The results for a wavy micro structured topography illustrate that the liquid interface follows the geometry but a phase shift appears, which is dominated by flow parameters. For a pyramidal micro structured topography a recession of solitary waves of the flow is documented through the development of a three dimensional flow structure. It can be concluded that the enhancement of the mass transfer is supported by the induction of stationary and non-stationary eddies caused by micro-structured topography. In the contribution results of the new adapted measurement system on micro structured topographies are presented.