Simulation of Spray Transfer Processes in Electrostatic Rotary Bell Sprayer

Abstract

A numerical study of the spray transfer processes in an electrostatic rotary bell applicator (ESRB) has been conducted utilizing code for a newly developed simulation code. This code consists of three modularized solvers: a fluid flow solver, a spray dynamics solver, and an electrostatic solver. The development of the code consisted of the following steps. First, the flow solver designed for an unsteady three-dimensional Navier-Stokes equation was developed to simulate the shaping airflow with the initial condition and the boundary condition supported by experimental data. Second, the particle trajectory solver, which interacts with the airflow by momentum coupling, was developed to apply the spray transport processes. Finally, the electrostatic solver was developed to calculate the electrostatic field within the two phase flow field. The integrated code created by combining those three solvers was then applied to simulate the paint spray transport processes according to the operating conditions of interest. The numerical results show that the spray shape is very sensitive to changes in the charge to mass ratio. The voltage setting is a dominant operating parameter affecting the numerical transfer efficiency. The voltage range studied was 0 kV to 90 kV. In addition, the transfer efficiency decreases as the shaping airflow rate increases. However, a high shaping airflow rate produces a more uniform distribution of spray mass on the target plane.

Schlieren Visualization of Shaping Air during Operation of an Electrostatic Rotary Bell Sprayer: Impact of Shaping Air on Droplet Atomization and Transport

“…Typically, an electric field is also established between the ERBS and the target to improve paint transfer efficiency. Its influence was studied by Im et al [13]; an integrated code was developed that included flows, droplet trajectories and electrostatic solvers as a function of the applied voltage settings and SA flow rates.Establishing high-quality surface finishes during automotive painting is a challenging task [14]. Numerous characteristics of the coating process profoundly influence the color, gloss, appearance, and effects of metallic additives.…”

“…Typically, an electric field is also established between the ERBS and the target to improve paint transfer efficiency. Its influence was studied by Im et al [13]; an integrated code was developed that included flows, droplet trajectories and electrostatic solvers as a function of the applied voltage settings and SA flow rates.…”

Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing

“…In the booth air flow model, the well-known conservation equations for mass and momentum, together with a standard k-turbulence model, are used [8,9]. The electric field model describes the physics of an electric field between the bells and the grounded surfaces generated by the emitting electrode of the spray bells.…”

“…In the particle flying model, spherical paint particles with the same density are assumed to be delivered from spray nozzles, and the momentum of particles is affected by three dominant forces: the drag force from the surrounding turbulent air flow, the electrical force from the electric field, and gravity. Based on these assumptions, the velocity of each particle is modeled based on Newton's second law of motion [9]. O'Rourke's statistics-based collision algorithm is used for characterizing particle collisions [10].…”

Integrated multiscale product and process control of polymeric coating curing

“…Those models can generate very valuable quantitative information about how (i) the coating topology (from wet to dry) could be dynamically changed, (ii) the solvent could be smoothly removed, (iii) the crosslinking reaction could take place, and (iv) common defects could be successfully detected, analyzed, and prevented. More sophisticated modeling and simulation techniques for characterizing the paint spray operations were developed, where neural networks, fuzzy logic, and CFD techniques were used in different components of the modeling and simulation systems [11][12][13][14][15][16]. However, the existing models are usually monoscale based.…”