A STUDY ON DROPLET VELOCITY OF ETHANOL DURING ELECTROSPRAYING PROCESS AT CONE-JET MODE

An analysis on the velocity characteristics of droplets generated from electrospraying is the key to understand the formation and evolution of the spray shape. Combining with the experimental results of ethanol electrospraying at cone-jet mode, a two-dimensional axisymmetric model of electrospraying was established. Based on the droplet motion equations, air motion equations, electric field equations and user-defined functions, the model was numerically solved to obtain the spray morphology, the space electric field distribution and the droplet velocity field distribution at cone-jet mode. The effect of air inlet velocity on the spray shape and velocity field distribution of ethanol/air coaxial jet was also discussed. The results indicate that the air flow field has a strong interaction with the droplets at the periphery of the spray, leading to a smooth variation of the droplet velocity distribution near the axis of the spray, while the droplet velocity distribution at the periphery of the spray varies drastically along the radial direction. As the coaxial air inlet velocity increases, the spray shape tends to diverge first. But when the air inlet velocity increases to be greater than the axial velocity of the spray droplets, the spray shape tends to gather. Therefore, in addition to changing the applied voltage, liquid flow rate or electrode pattern, controlling the air inlet velocity to affect the spray velocity field can be an efficient way to control the electrospraying.