Mitigation of flow separation using DBD plasma actuators on airfoils: A tool for more efficient wind turbine operation

In this study, dielectric barrier discharge plasma actuators (DBD-PA) were used to actively control flow separation over a NACA0024 airfoil. Experiments were conducted at a free stream velocity up to U ≈ 10 m/s (Re ≈ 1.3 × 105) in an open-circuit blower type wind tunnel with a test section measuring 200 mm × 200 mm × 600 mm. The airfoil model was designed specifically to incorporate minimum flow disturbances from the components of the DBD-PA and was made using rapid prototyping. A sheet of dielectric polyimide (125 μm) with copper electrodes (35 μm) was attached to the outer surface of the airfoil. A layer of DBD plasma across the airfoil was produced when a peak-to-peak voltage of Vp-p = 8.0 kV was applied between top and bottom electrodes at a frequency of fp = 9.0 kHz. This development of plasma produced a tangential air jet across the surface of the airfoil, which reached its maximum value (uj-max) in the range of 0.5 m/s < uj-max < 0.7 m/s. Varying degrees of separation flow control was observed under these conditions. Performance comparisons were made between electrodes located at the leading edge (LE) and the quarter chord (QC, 25% of chord length) at angles of attack of α = 8°, 12°, 16°. The plasma-induced jet velocities and flow profiles were measured using particle image velocimetry (PIV). Characteristics such as power consumption, voltage waveform, and current magnitude were quantified through the use of a digital oscilloscope.

► Dynamic behaviors of flow separation were measured by particle image velocimetry.
► Effectiveness of active separation control by DBD plasma actuator was estimated.
► DBD plasma actuator at leading edge is effective for turbulent separation control.
► DBD plasma actuator at quarter chord is effective for laminar separation control.