Simulation of the Shaping Air and Spray Transport in Electrostatic Rotary Bell Painting Process

A numerical study of the electrostatic rotary bell paint spray transport region is carried out using a newly developed simulation code. Firstly, a time-accurate Navier-Stokes equation solver, utilizing the space-time conservation-element/solution-element methods, simulates the shaping air based on the known boundary and initial condition. Secondly, a particle trajectory solver, which interacts with airflow by momentum coupling, is applied to simulate the paint spray characteristics. Thirdly, an analytical solution of electrostatic field is coupled to simulate realistic electrostatic rotary bell paint sprayer. The integrated software is then applied to simulate the paint spray transport processes according to the operating conditions of interest. The numerical results show that the spray flow is very sensitive to some of the operation parameters. The transfer efficiency and the uniformity of paint distribution increase with charge-to-mass ratio and electrostatic voltage. However, with high shaping airflow rate, the numerical transfer efficiency decreased while the mass distribution becomes more uniform. The parametric study supplies valuable fundamental information to the spray transfer process, although more research is needed to include the effects of atomization and more electrostatics physics.