Primary breakup of liquids using a high-speed rotary bell atomizer for spray painting processes

The present contribution deals with numerical studies of the primary liquid breakup process using a commercial high-speed rotary bell atomizer. The first part of the investigations focuses on the film formation on the distributor disk and the inner surface of the rotary bell. Numerical simulations using the volume of fluid (VOF) approach were carried out. A non-Newtonian liquid is used to investigate the effect of the viscosity on the initial wetting, the film formation process and the film thickness distribution on the bell. The Herschel-Bulkley model is considered to describe the shear-thinning (pseudoplastic) behavior of the fluid. A non-homogeneous film structure is found on the inside surface of the rotary bell. This is also observed in experimental investigations using a high-speed camera. The following disintegration process is studied by applying an appropriately fine computational mesh. The VOF method and Reynolds stress model are used to calculate the disintegration process and the two-phase flow field. The numerical results are compared with images which are recorded by means of a high-speed camera.