Numerical study on piezoelectric inkjet with liquid compressibility

A two-dimensional numerical model for a cylindrical piezoelectric inkjet was developed to analyze the ink droplet formation and meniscus behavior, considering the ink compressibility. The propagation of the acoustic pressure wave, which was generated by the piezo actuator, could be simulated by considering the compressibility of the ink. The volume of fluid method was employed for multiphase flow, while the dynamic mesh method was used to implement the piezo actuation. In this study, the key operational parameters of operating voltage, compressibility of working fluid, dwell time of waveform, contact angle, and restrictor dimensions were varied to conduct a comprehensive parametric analysis. The underlying mechanism governing droplet formation could be identified through the analysis of the propagation of successive acoustic pressure waves. Furthermore, the volume fraction and mass flow rate results were used to analyze the jetting performances quantitatively and qualitatively. The mass flow rate results were used to determine the implicit effect of physical properties, such as the viscosity and surface tension, through momentum analysis. The developed model including ink compressibility accurately predicted the behavior of the inkjet jetting and the meniscus motion. In addition, it allows visualization of the internal flow structure and optimization of operating conditions to increase the stability and productivity of inkjet printing.