ELECTROHYDRODYNAMIC CHARACTERISTICS OF LIQUID BRIDGE FORMATION AT THE DRIPPING MODE OF ELECTROSPRAYS

A detailed visualization study on the evolution of Liquid bridge formation and fracture from a capillary is reported. By means of high-speed microscopy with high time-space resolution, special attention has been paid to the formation dynamics of the liquid bridge in the dripping mode, the change of interface structure and the fracture dynamics behavior of hydraulic bridge are studied, and the action rule of time characteristic number, electric Bond number and half-moon angle on liquid length and fracture order of liquid bridge is obtained. The results show that the fracture length of liquid bridge depends on the ratio of viscosity to surface tension, but is little affected by the relaxation time of charge. Under low voltage condition, the change of liquid bridge relative length for each experiment medium is not obvious, while the relative length of liquid bridge grows rapidly during high voltage condition. With the continuous increase of electric Bond number, the change of liquid bridge length is more obvious under the higher Bond number, and a mutation zone occur which shows the transition of the atomization model, this means the mutation of liquid bridge is a transition signal of atomization modes. With the changes of the formation angle of liquid bridge upstream and downstream, the transition behavior of jet flow in different physical media varies greatly. In the case of ethyl alcohol, the increase in the number of electric bonds causes the dropping mode to first transition to the spindle mode, while in the case of biodiesel, the pulsation mode rather than the spindle mode will first appear after the dropping mode. It is of great significance to reveal the transition law of charged micro fluidic atomization model and enrich the theory of electrostatic atomization.