The effect of electrohydrodynamic flow on the current conduction on thin ceramic powder layers under corona discharges

Dielectric ceramic powders used are silica and alumina, and experiments are conducted for applied voltage from 0 to -50 KV, dry nitrogen gas flow rate from 0 to 2.5 L/min, and mean powder size from 30 to 250 /spl mu/m. Corona discharge is generated by a hollow to mesh plate electrode geometry. Gas flow is supplied from a hollow electrode and flow through the powder layer is supported by mesh electrodes. EHD flow is evaluated from pressure drop measurements. The results show that the time averaged conduction current nonmonotonically depends on the powder radius and on dielectric constants. The pressure drop characteristics, and hence EHD flow, depend on the polarity of the applied voltage.