An image analysis of positive ionic wind velocity under the DC corona discharge in needle-cylinder electrode system

In this work, a micro electrohydrodynamical (EHD) gas pump using a needle-cylindrical electrode system was constructed for an application of ionic wind to fluid flow operations without mechanical parts. The experimental EHD pump was consisted of a tapered glass tube (2 to 10 mm in inner diameters, 45 mm in an axial length) attached with the electrode system, where the needle electrode (1 mm in a diameter, 30 degree in a tip angle) was used as a conventional discharge electrode and the ring electrode located on outer surface of the tapered glass tube was grounded. Under DC or AC dielectric barrier discharge conditions, the ionic wind generation inside the tapered glass tube was operated as a small-sized gas jet source. The working gas was evaluated for the room air. The fluid flow visualization was conducted by a laser-sheet monitoring method and the quantitative flow velocity measurement was by a particle image velocimetry (PIV) with a high-speed digital camera. The characteristics of ionic wind velocity were analyzed as functions of the corona discharge current and the charge injection from the discharge electrode. This paper presents the experimental approach to the ionic wind characteristics depended on several electrical conditions of the barrier discharge current and the charge injection into the flowing air. The EHD phenomenon is quantitatively discussed in non-dimensional EHD parameters.