Mechanisms of electrospray jet formation and atomized droplet motion in pulsed-jet mode

Electrospray (ES) has attracted significant interest due to its advantages in generating uniform droplets and enabling controlled deposition. However, the complex interactions and droplet motion mechanisms between fluids and electric fields are still not well understood. Herein, this study presents a three-dimensional numerical model based on the volume of fluid and Lagrangian approaches to simulate the ES process in the pulsed jet mode. The model accurately captures the morphology and the atomization characteristics in the pulsed jet mode of ES. The effects of voltage and Reynolds number on the length of the non-atomized zone (including quasi-static Taylor cone, transition zone, and jet), diameter of the jet breakup, and atomization characteristics are discussed. Also, the mechanism of atomized droplets is revealed by analyzing the magnitudes of different types of forces imposing on the droplets in the electric field. The results indicate that higher Reynolds numbers lead to increased length of non-atomized zone and diameter of jet breakup, while the elevated voltages enhance atomization. Electric and Coulomb forces are, respectively, the dominant forces of forming the jet and expanding the atomization angle. Coulomb force increases the atomization angle, and electric field force increases the velocity of atomized droplets. Gravity and drag-force effects are relatively negligible throughout the atomization process. These findings contribute to a better understanding of the electrospray mechanisms and provide insights for optimizing electrospray applications.