An experimental and numerical study of the spray transfer processes in an electrostaic rotating bell spray

The trend of the current automotive finishing industry is to use more electrostatic rotating bell (ESRB) applicators because of their higher transfer efficiency. The flow physics related with the transfer efficiency is strongly influenced by the operating parameters.; The purpose of this thesis is to understand the paint spray transfer processes driven by the ESRB. An experimental and numerical study incorporated the current technology and modern computational fluid dynamics (CFD) method were carried out.; In the experimental study, the flow visualization, the drop size measurement and the velocity distribution of the spray painting system under operating conditions were conducted. The optical techniques used in this study are light sheet visualization by copper vapor laser and phase Doppler particle analyzer (PDPA) system. The results show that the bell rotating speed is the most important influencing parameter for the atomization processes and the drop size distribution, the high voltage and the shaping airflow rate settings significantly modify the spray transport, and the liquid flow rate is related with the spray transport.; Parallel to the experimental works, this thesis performed a numerical study of three physical processes in paint spray transport region. Initially, based on the known experimental data, an unsteady three-dimensional Navier-Stokes solver of the shaping airflow was developed and validated. Then, the particle trajectory solver and the analytical solution of electrostatic field were applied to simulate the particle mobility. Finally, the newly developed software was applied to simulate the paint spray processes according to the operating conditions of interest. The numerical results show that increasing the bell speed results in widening the flow pattern and more uniform velocity distribution when it is reaches a steady state and increasing the high voltage setting, the numerical transfer efficiency increased and the spray mass uniformly distributed on the target plane. With high shaping airflow rate, the numerical transfer efficiency decreased and the mass distribution became uniform. In addition, other results of the parametric study will support valuable information to understand the spray transfer process.