Numerical investigation of Electrostatic Spray Painting Transfer Processes for vehicle Coating 2019-01-1856
In this study, we examined numerical investigations of the electrostatic spray transfer processes in the Rotary bell spray applicator, which is implemented in a full 3D representation. The code implemented and developed in this simulation includes air flow, spray dynamic, tracking paint droplets and electrostatic modularized solver to present atomization and in-flight spray phenomena in the spray forming procedure. The freeware code OpenFOAM package is employed. Airflow shaping simulated via unsteady 3D developmental compressible Navier-Stokes method. The solver for particle trajectory was developed to illustrate the process of spray transport and also the interaction of airflow and particle solved by momentum coupling. The electrostatic field was calculated with the two-phase developmental electrostatic solver. As the numerical results in this paper indicated dominant operating parameter voltage setting, the rotational speed and air-paint flow rate deeply affecting on the spray shape and transfer efficiency (TE). By increasing the shaping airflow more uniform distribution mass of paint produced but the TE decreases. The spins of the bell forced the paint to falls off from the bell edge and enters to the high-velocity airflow. The size distribution is intensely sensitive to the bell rotation speed. Our results demonstrate the validity of the solutions and also the applicability of it in reducing the production costs in the painting shop. Unsteady and Dynamic treatment of air flow is described by using Large eddy simulation (LES) and compressible k-ω SST RANS turbulence models, whereas the movement of the paint particles is modeled by an approach of tracking. Droplet size distribution, also the electrical potential effect on its size and form can be predicted. The paint spray structure obtained from the numerical simulations are compared with the experimental data at the same working condition with suitable quantitative accuracy.