Control of vortex shedding from a blunt trailing edge using plasma actuators

An experimental investigation on the use of plasma actuators for vortex shedding suppression is performed. The vortex shedding phenomenon at the blunt trailing edge of an elongated D-shaped body is specifically investigated. The study is focused on the laminar boundary layer regime on an elongated D-shaped flat plate of 12 mm thickness at free-stream velocity up to approximately 10 m/s. Dielectric barrier discharge plasma actuators are utilized in several geometrical configurations at the trailing edge of the plate and are operated in continuous and pulsed mode. Several operational parameters such as applied voltage, carrier and pulse frequency and duty cycle are investigated. Results reveal that tangential actuation both in the downstream or upstream direction yields very limited effects on the coherent organization in the wake. Instead, symmetrical actuation from the base edges towards the wake centerline, proved to be very effective prompting a more detailed study of this actuator configuration. At external flow conditions, the reduction of the Kármán wake component is monitored by the modal energy spectrum obtained from proper orthogonal decomposition of PIV data in the stream-wise/wall-normal plane of the developing wake region. The suppression of coherent vortex shedding is further ascertained with time-resolved visualizations obtained by high-speed PIV and spectral analysis conducted with hot-wire anemometry. In order to gain a complete understanding of the forcing mechanism, the velocity field induced by this actuator configuration is additionally investigated by means of high-speed PIV measurements conducted in initially quiescent flow. It is verified that the suppression mechanism involves the breakup of communication between the two shear layers simultaneously to moderate momentum addition into the recirculation area.

► Vortex shedding from a blunt trailing-edge is supressed using plasma actuators.
► A novel configuration of plasma actuator at the trailing-edge is applied.
► The effect of the operating parameters of the plasma actuator is investigated.
► The flow field is visualized using time-resolved Particle Image Velocimetry.