Electrohydrodynamic flow induced by surface dielectric barrier discharge in narrow channels

A surface dielectric barrier discharge induces a gas flow called an electrohydrodynamic (EHD) flow. Flow velocity measurements with a laser Doppler velocimeter (LDV) have indicated that the driving force of the EHD flow exists within a height of less than 0.3 mm from the dielectric barrier, and therefore, EHD flow generation in a narrow channel of a submillimeter order was attempted by placing a dielectric plate over the discharge. However, a positive charge that accumulated on the inner surface of the upper plate probably weakened the driving force, resulting in no EHD flow in a rectangular channel with a height of 0.5 mm. To prevent such unipolar charge accumulation, the discharge was also generated on the upper inner surface and an EHD flow could then be generated in the narrow channel. Thus, generating the discharge along the inner surface of a channel effectively makes the driving force stronger. Although the driving force could be induced in a channel of a submillimeter order or less, the minimum channel size for EHD flow generation was limited by an increase in pressure loss with decreasing channel size.