Post-dispersion electrification of droplets

•Aerosol particles dispersed by a pneumatic supersonic atomizing head.•Post dispersion electrification of droplets a contact method with external high voltage electrode.•The space charge component of the electric field is decisive for the final Q/m ratio value.•Bipolar nature of a charge carried by droplets leaving electrification system.

Electrification of aerosol particles dispersed by a pneumatic atomizer is presented in the paper. For post dispersion electrification of droplets a contact method with external high voltage electrode was proposed. Experiments were carried out using supersonic atomizing head, equipped with a high voltage mesh electrode, placed co-axially and perpendicularly to the droplets stream and closely to the atomizing head. Results of experimental investigations have shown, that the Q/m ratio values depends on the liquid feed rate according to the power type function. Two steps electrification model with a space charge was proposed for explanation of the observed dependence. Calculations carried out on the basis of proposed model confirmed, that the space charge component of the electric field is significant for the final Q/m ratio value, and allow to determine Q/m value with accuracy on the level of 10%. The model suggests bipolar nature of charge carried by droplets leaving the electrification system.