Experimental results in DBD plasma actuators for air flow control

In this work several planar dielectric barrier discharge fluid-dynamics actuators have been experimentally investigated. The actuator is made by an electrode pair separated by a dielectric. It is characterized by a planar geometry and it induces a volume force on the gas above it which modifies the fluid-dynamics within the aerodynamic boundary layer. Several actuator geometries, dielectric materials, a.c. supply voltages and supply frequencies have been used. Rotational and vibrational temperatures have been determined by means of spectroscopic measurements. Vibrational temperatures have been found to be one order of magnitude higher than the rotational ones, confirm-ing the non-thermal behavior of the discharge. The translational temperature has been evaluated by thermographic observations of the dielectric surface heated by the plasma. The values of the translational temperature are in a very good agreement with those of the rotational temperature. Electric measurements have been carried out to determine the average power delivered to the discharge and to estimate the average electron number density. In the plasma induced by the discharge above the actuator an average electron density of 4 ÷ 15 · 1017 m-3 has been determined. The gas speed of the induced wall jet has been measured with a Pitot tube. The average power delivered to the electrodes increas-es with a power law of the applied voltage (exponent ≈ 3 ÷ 5) and linearly with the supply frequency. The induced speed increases with the increase of the average power until a plateau is reached. The efficiencies of the different actuators have been compared by evaluating the relation between average power and induced gas speed.