The Electro-Hydro-Dynamics (EHD) interaction, induced in atmospheric pressure still air by a surface dielectric barrier discharge (DBD) actuator, had been experimentally studied. A plasma aerodynamic actuator array, able to produce a vectorized jet, with the induced airflow oriented toward the desired direction, had been developed. The array was constituted by a sequence of single surface DBD actuators with kapton as dielectric material. An ac voltage in the range of 0–6 kV peak at 15 kHz had been used. The vectorization had been obtained by feeding the upper electrodes with different voltages and by varying the electrical connections. The lower electrodes had been connected either to ground or to the high voltage source, to produce the desired jet orientation and to avoid plasma formation acting in an undesired direction. Voltage and current measurements had been carried out to evaluate waveforms and to estimate the active power delivered to the discharge. Schlieren imaging allowed to visualize the induced jet and to estimate its orientation. Pitot measurements had been performed to obtain velocity profiles for all jet configurations. A proportional relation between the jet deflection angle and the applied voltage had been found. Moreover, a linear relation had been obtained between the maximum speed in the jet direction and the applied voltage. The active power of the discharge is approximated by both a power law function and an exponential function of the applied voltage.

Articles you may be interested inEffect of the charge surface distribution on the flow field induced by a dielectric barrier discharge actuator

The electric potential distribution induced on the surface of an aerodynamic plasma actuator, operating by means of a surface dielectric barrier discharge (DBD), has been studied both numerically and experimentally. Three actuators made with three different dielectric materials (Teflon, Plexiglas, and glass) have been used. The geometric configuration of the three actuators is the same one. An electrode pair separated by a 2 mm thick dielectric sheet constitutes the DBD actuator. The exposed high voltage electrode has been fed by a 5 kHz a.c. electrical signal. Voltage values between 7.5 and 15 kVp have been used. Measurements of the distribution of the electrical potential in the dielectric surface, generated by the charge deposited on it, have been done. Numerical simulations allowed to evaluating the charge distribution on the dielectric surface. The discharge has been switched off after positive and negative plasma currents. The measurements have been carried out after both phases. The potential distribution is always positive. The charge build up takes place several centimeters downstream of the upper electrode for an extension broader than that of the plasma on the dielectric surface. The charge distribution strongly depends on the switching off phase and is heavily affected by the dielectric material. In order to evaluate the discharge structure and the extension of the plasma, images have been taken also.

The Electro-Hydro-Dynamics (EHD) interaction induced by a surface dielectric barrier discharge in the aerodynamic boundary layer at one atmosphere still air has been investigated. Three different geometrical configurations of the actuator have been utilized. In the first configuration, an electrode pair separated by a 2 mm dielectric sheet has been used. The second and the third configurations have been obtained by adding a third electrode on the upper side of the dielectric surface. This electrode has been placed downstream of the upper electrode and has been connected to ground or has been left floating. Three different dielectric materials have been utilized. The high voltage upper electrode was fed by an a.c. electric tension. Measurements of the dielectric surface potential generated by the charge deposition have been done. The discharge has been switched off after positive and negative phases of the plasma current (the current phase was characterized by a positive or a negative value, respectively). The measurements have been carried out after both phases. The charge distribution strongly depended on the switching off phase and was heavily affected by the geometrical configuration. A remarkable decrease of the charge deposited on the dielectric surface has been detected when the third electrode was connected to ground. Velocity profiles were obtained by using a Pitot probe. They showed that the presence of the third electrode limits the fluid dynamics performance of the actuator. A relation between the charge surface distribution and the EHD interaction phenomenon has been found. Imaging of the plasma has been done to evaluate the discharge structure and the extension of the plasma in the configurations investigated.

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