On the Characterization of Electrohydrodynamic Pumping under DC and AC Corona Discharge Settings

This study investigates the pumping performance of a custom-built corona discharge setup (needle-to-plate electrodes) for inducing electrohydrodynamic (EHD) circular motions in fluids. Velocity of silicone oils with kinematic viscosities of 50 cSt and 100 cSt under DC and AC applied voltages are studied experimentally via particle image velocimetry (PIV) and verified using a continuity equation. Both fluids experienced increase in azimuthal velocities when the DC corona applied voltages increased from 7 kV to 10 kV with increments of 1 kV, exhibiting a scaling effect. An analytical model for the flow under DC corona voltages is also derived using the Navier-Stokes equations. In addition, a parametric study is conducted under alternating sinusoidal current via changing input signal frequency, while maintaining the input amplitude (i.e., voltage range). This part of the study suggests that the EHD pump acts as a low-pass filter. Overall, the results of this study can be used for an efficient contact-less and controllable manipulation of dielectric fluids (e.g., silicone oils) for potential applications in fluid transport, and emulsion formation and separation.