EHD surface waves of diesel oil thin films generated by wire-plate barrier discharges

An experimental investigation has been conducted to study electrohydrodynamically (EHD) induced surface wave phenomena on the surface of dielectric diesel oil thin films under wire-plate barrier discharges. Experimental arrangements used in the present investigation consisted of a corona wire, air gaps, thin oil film, mylor sheet and conducting transparent sheet placed on the lucite plate. Positive dc (on/off) high voltage was imposed on the corona wires and the conducting sheet was grounded. Diesel oil is used as a working fluid (/spl epsi//sub s/=2.2 and /spl sigma/5/spl times/10/sup -/5 /spl mu/S/m). The experimental results show that: (1) Thin oil film started to deform immediately when dc voltage is imposed and a small elongated ring shape hydraulic jump expanding wave is formed; (2) after thin oil film becomes significantly charged, a formation of depressing expanding elongated ring-shaped waves are observed and relatively uniform oil thin films formed below corona wires; (3) after voltage is off, a formation of depression expanding waves is observed and the surface waves keep forming and decay until all the electric charges at the surface of the diesel oils are relaxed.