Simulation of Droplet Ejection for a Piezoelectric Inkjet Printing Device

A computer-aided analysis system has been developed in this study to simulate the formation, ejection, and impact of liquid droplet in a piezoelectric inkjet printing device. The effects of voltage pulse of the piezoelectric actuator and surface tension of the liquid on the droplet ejection phenomena are evaluated by the simulation system. The droplet ejection is a fluid flow phenomenon, which involves two phases (liquid and gas) and free surface evolution of the liquid. The computer simulation system is based on a SOLA (Solution Algorithm) scheme coupled with VOF (Volume of Fluid)/PLIC (Piecewise-Linear Interface Construction) and CSF (Continuum Surface Force) models. To simplify the simulated system, only the nozzle region of the inkjet printing device is considered. The behavior of the piezoelectric diaphragm is imposed on the simulation system by a moving boundary, which is determined by the velocity profile corresponding to the driving voltage. The effects of the surface tension of the liquid are evaluated by the CSF model. The results show that comprehensive images of the inkjet dynamics, which include the evolution of the droplet; from formation, ejection to impact, can be revealed by the simulations. The effects of surface tension of the liquid on the size and flying velocity of the droplet as well as the formation of the satellite droplets can also be evaluated by the simulation system.