Effects of Actuating Pressure Waveforms on the Droplet Behavior in a Piezoelectric Inkjet

This paper presents a numerical analysis of a piezoelectric actuated droplet generator. A three-dimensional finite difference numerical model based on a SOLA (solution algorithm) scheme for the solution of governing equations of the flow field and a volume-of-fluid method for tracing the fluid interfaces are presented. The surface tension is modeled using a continuum surface force concept and thus computed as a function of the interfacial curvature. The pressure pulse at the nozzle inlet, which is related to the applied voltage, was imposed according to the propagation theory of acoustic waves. The effects of the pressure waveforms, including positive and negative pressure amplitudes, operating period and acceleration of the positive pressure, on the droplet ejection process are simulated. The performance of piezoelectric inkjet: droplet break time, droplet tail length, droplet velocity and droplet volume are analyzed. The simulation results show that the tail length and volume of the droplet increase with the amplitude of the positive pressure and operating period. The breakup time of the droplet is shorter when the amplitude of the negative pressure increases. The factors that influence satellite droplets are also investigated in this study.