Experimental Characterization of EHD Flow in an Electrostatic Air-Oil Droplets Separator Using Particle Image Velocimetry

In the present work, results of electrohydrodynamic (EHD) flow field in a wire-plate air-oil droplets electrostatic separator under positive polarity are presented. Using Particle Image Velocimetry (PIV), the structure of EHD flow under fully developed primary laminar gas flow is investigated and corresponding flow patterns are studied. Velocity distribution results show that the transverse velocity induced by EHD flow depends significantly on applied voltage and the cross-section plane position of the separator. Detailed transverse velocity distribution profiles under different ratio between electrostatic force and inertial force of droplets (Ehd/Re²) are presented. Oscillating jets are observed under a relatively low Ehd/Re² ∼ 4 and counter rotating vortices around the wire for large Ehd/Re² > 90 are characterized in this experiment. Contrary to EHD flow patterns for fine solid particles, no von Karman vortex was observed downstream of the charged electrode wire.