On the negative corona and ionic wind over water electrode surface

• We exam the ionic wind by DC corona discharge at atmospheric pressure.
• Voltage has a positive effect on ionic wind strength and active area.
• There is an optimal gap distance for a wider as well as stronger ionic wind.
• Blunter needle enhances both the active area and the wind strength.
• A rotation phenomenon of corona is observed and discussed.

The DC corona discharge in air and the induced ionic wind were investigated in the needle-to-water system at atmospheric pressure. The water deformation was measured under various conditions, and wind pressure and active areas were estimated accordingly. The effects of applied voltage, gap spacing and tip radius on the corona ionic wind were studied and the qualitative analysis was provided. Self-rotation of corona discharge was observed in experiments. The results show that higher voltage or electric field strength results in a stronger ionic wind. The active area increases with applied voltage below a voltage threshold. There is an optimal gap distance for a wider as well as stronger ionic wind and blunter needle we used leads to an enhancement on both the active area and the wind strength. The wind velocity reaches 7 m/s at optimized condition in the present system. The rotation of corona discharge helps to improve the active area and uniformity of the treating area which may be associated with the chemical reaction of the water surface.