Viscosity effect on EHD spraying using AC superimposed on DC electric field

Electrohydrodynamic (EHD) spraying is a method for charged aerosol generation by electrical forces alone. The EHD method of spraying allows also synchronized generation of droplets which are of uniform size by using pulsed or AC superimposed on DC high voltage. The results of the investigations of the break-up process of the liquid jet for combined DC and AC excitation voltage are presented in the paper. The DC voltage was set to 7.5 kV with superimposed alternating voltage 5 KVpp. It was shown experimentally that with increase in the liquid viscosity (for water/glycol mixtures) the range of synchronized generation in terms of flow rate and AC frequency becomes narrower. For a fixed flow rate the size of the generated droplets decreases with increasing AC frequency. It was established experimentally that increase in viscosity causes a decrease in the jet diameter, which results in smaller drop size