High-fidelity simulations of a rotary bell atomizer with electrohydrodynamic effects

Rotary Bell Atomizers (RBA) are extensively used as paint applicators in the automotive industry. Atomization of paint is achieved by a high speed rotating bell cup in the presence of a background electric field. Automotive paint shops account for 70% of the total energy costs [Galitsky et. al., 2008], 50% of the electricity demand [Leven et. al., 2001] and up to 80% of the environmental concerns [Geffen et al., 2000] in an automobile manufacturing facility. The atomization process in an RBA affects the size and the velocity distribution of the droplets which subsequently control the transfer efficiency and the surface finish quality. Optimal spray parameters used in industry are often obtained from expensive trial-and-error experimentation methods. In this work, three-dimensional near-cup atomization is simulated computationally using a high-fidelity volume-of-fluid transport scheme that includes electrohydrodynamic (EHD) effects. Atomization quality metrics such as droplet size and droplet charge density distributions are analyzed for different operating conditions. This cost-effective method of research aims to identify the effect of EHD on the spray to help maximize the transfer efficiency of the device.