Measurements of unsteady electrohydrodynamics flow from injection charges on free surface by particle image velocimetry

The authors have been researched on the velocity field measurements of the electro-hydrodynamics (EHD) flow caused by AC corona discharges. From the experimental results for several kinds of dielectric liquids with some viscosity it has been found a transition process from the steady EHD fluid flow toward the turbulent flow. Since this process depends significantly on the viscosity of EHD fluid, it has a threshold determined by the Reynolds number. This paper describes about the experimental results of this transition process obtained from the silicone oil with different viscosities. To understand the fluid flow structure of EHD caused by the corona discharges, the velocity fields of the unsteady EHD fluid flow are successfully obtained by means of the flow visualization technique and the particle image velocimetry (PIV) technique.