Hydrodynamics and Heat Transfer in a Liquid Film Flowing Over a Spinning Disk With Wall Topography

摘要

One of the most commonly used methods of liquid atomization is spinning disk atomization. This technique makes use of centrifugal forces to create a thin liquid film spreading radially over a disk. The film flowing along the disk is mostly wavy. The waves have a negative influence on the drop size distribution in the atomization process. It is known that the waves on falling films can be suppressed by using walls with longitudinal grooves. Due to the similarity of the physical mechanisms governing the wave development on falling films and on films flowing over spinning disks, we suggest using grooved surfaces for suppressing the waves in spinning disk atomizers. We develop a mathematical model for description of the film dynamics on a spinning disk with wall topography using the long-wave theory. It takes into account the centrifugal force, inertia, surface tension, and heat transfer. The wall surface topography induces a thermocapillary flow in the liquid film, which significantly affects the film thickness distribution. We develop an experimental method for high-speed measurements of film dynamics on a spinning disk. The average film thickness qualitatively agrees with the basic theoretical solution. Quantitative discrepancies can be attributed to the film waviness.