Viscosity Effect on the Electrospray Characteristics of Droplet Size and Distribution

Electrostatic spraying is a method of atomizing a fluid using a high voltage as an atomization auxiliary device, and various spraying modes exist according to experimental parameters and viscosity. A maximum of 11 spray modes were identified according to the changes in the applied voltage and flow rate. To produce fine droplets and a uniform size, which are the advantages of electrostatic spraying, in this experiment, the Sauter mean diameter (SMD) and SMD distribution were evaluated in each spray mode of electrostatic spraying. By comparing the other spray modes with the cone jet mode, it was confirmed that the maximum difference of the SMD was less than 1.5 times and the standard deviation of the rotated and pulsed jets was 2.5 times or more. In the cone shape range, the SMD and SMD distribution according to the applied voltage confirmed that the droplet size was the smallest in the middle of the cone jet mode, and the droplet distribution was also narrow. In the cone jet mode, the droplet size increased linearly with the viscosity and flow rate. In addition, the droplet distribution range was distinctive depending on the type of fluid. In the case of the relationship between the droplet size and current, it was proven that the higher the viscosity, the higher the current value for the same SMD; furthermore, the difference in the current-SMD increase rate was insignificant. Through experiments, this work presents experimental data of SMD, SMD distribution, and current-SMD in electrostatic spray experiments under various conditions.