We propose and demonstrate reduction of aerodynamic drag for a realistic geometry at highway speeds using serpentine dielectric barrier discharge actuators. A comparable linear plasma actuator fails to reduce the drag at these speeds. Experimental data collected for linear and serpentine plasma actuators under quiescent operating conditions show that the serpentine design has profound effect on near wall flow structure and resulting drag. For certain actuator arrangement, the measured drag reduced by over 14% at 26.8 m/s (60 mph) and over 10% at 31.3 m/s (70 mph) opening up realistic possibility of reasonable energy savings for full scale ground vehicles. In addition, the power consumption data and drag reduction effectiveness for different input signals are also presented.
Micron size dielectric barrier discharge actuators, designed for minimal footprint area and weight penalty, show a wall jet up to 2.0 m/s consuming 15 W/m of electrode. A torsional balance measures force up to 3 mN/m of electrode and demonstrates equivalent “thrust effectiveness” (induced force/power) to macroscale actuators. Compared with reported macroscale data, the microscale actuator shows a 31% increase in energy conversion efficiency. Per unit actuator mass, both the force and the velocity induced by microscale actuators show an order of magnitude (22.1 and 18.5 times, respectively) increase over macroscale actuators, making them suitable for distributed flow control applications.
Dielectric barrier discharge actuators tested for thrust inducement between 13 and 101 kPa ambient air pressure show that as the pressure decreases, the thrust increases to a maximum, then drops steadily approaching zero while the power consumption monotonically increases. The amplification in induced thrust at the peak ranges from a few percent to several folds of the thrust measured at atmospheric condition. The effect is more pronounced for thinner dielectrics at lower operating voltages than thicker dielectrics at higher operating voltages and is fairly independent of the ground electrode width. Results identify several optimal control parameters for high-altitude operations.
Dielectric barrier discharges (DBDs) occur in the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to a high voltage supply. A quartz coaxial DBD tube, filled with argon, has been studied and an electrical model characterizing the discharges has been proposed. The proposed model considers the geometry of the DBD tube, gas gap spacing and the properties of the dielectric barrier material. A sinusoidal voltage up to 2.4 kV peak with frequencies from 20 to 100 kHz has been applied to the discharge electrodes for the generation of microdischarges. By comparisons of visual images and electrical waveforms, the filamentary discharges have been confirmed. The simulated discharge characteristics have been validated by the experimental results. A good correlation between the experimental and simulated results was found, which is used to deduce the circuit impedance and other electrical parameters, in particular, the conduction current, charge accumulation, energy deposited and consumed power during discharges.
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