Simulations of hydrodynamics of droplet coating process using airless rotary sprayers

Hydrodynamics of droplet coating process are simulated using an airless rotary sprayer by means of CFD-discrete element method (DEM) with JKR contact model. The surface energy parameter used in the JKR model is calibrated by a virtual accumulation angle test. A reasonable wall-droplet surface energy is suggested according to accumulation angle distribution. The droplet translational and angular velocities are predicted at different rotation speeds of the rotary sprayer labeled I, II and III. For stationary rotary sprayer coating process, the droplet translational and angular velocities, normal and tangential forces and energy losses are proportional to rotation speeds. As the rotary sprayer moves forward, the droplet-wall collision normal and tangential forces and energy losses are large near the inlet region and trends constantly in the developed region. This work suggests that DEM could be a useful method to study the effect of rotation speeds on droplet-wall contact interactions in paint droplet coating process.