Influence of an Electrohydrodynamic Actuator on a Turbulent Boundary Layer Along a Flat Plate

For some years, the use of electrohydrodynamic actuators has been receiving special attention. These actuators have important advantages like simplicity, no moving part, a short electrical response time and a total electric control. The electrohydrodynamic actuator used here consists in two electrodes flush mounted on a flat plate, generating a corona discharge at close vicinity of the wall. Positive ions created at the anode move outside the immediate vicinity of the ionization zone and drift to the negative electrode. Momentum transfer as a result of collision between drifting ions and neutral air molecules gives rise to the electrohydrodynamic flow known as ionic wind. In this paper the ionic wind is used in order to modify the properties of a turbulent boundary layer. Profiles of the boundary layer are presented for velocity up to 25 m/s. They show the influence of the polarity of the discharge, resulting in a velocity decreasing or increasing. In the case of increasing velocity, they show an important drag reduction (30% at 10 m/s) and a boundary layer thickness reduction of about 20% at 10 m/s.