ATOMIZATION CHARACTERISTICS OF A HIGHSPEED ROTARY-BELL PAINT APPLICATOR

An experimental study was conducted on the influence of fluid properties and operational parameters on the atomization characteristics of a high-speed rotary-bell paint applicator. Drop size measurements near the bell edge were complemented with high-speed photography to investigate the filming characteristics, atomization modes, and ligament disintegration mechanisms of this type of applicator. Surface tension was varied by a factor of 2.5 and viscosity by a factor of 100. Rotational speeds ranged from 4000 rpm to 40,000 rpm, while the liquid mass flow rate was varied from 0.67 to 6.67 g/s. It was found that high-viscosity fluids film the bell very evenly and produce long regular ligaments, whereas low-viscosity fluids film incompletely and produce very irregular ligaments that disintegrate near the bell edge. Mean drop size was found to be fairly insensitive to large changes in flow rate and viscosity at bell speeds higher than 20,000 rpm.