PI/Al2O3 nanocomposite based long lifetime surface dielectric barrier discharge plasma actuator

Polyimide (PI) based surface dielectric barrier discharge (SDBD) plasma actuators (PAs) have been widely used in the plasma flow control field due to its flexibility and adhesion, while it has a key drawback of a short lifetime due to the degradation under the plasma processing. There is a strong demand of long lifetime SDBD plasma actuator for its application on the wind turbine, aircraft and aero-engine. This paper reports a novel long lifetime SDBD plasma actuator using PI/Al2O3 nanocomposite as a dielectric barrier. A double-layer construction dielectric, including one layer of PI/Al2O3 nanocomposite film and one layer of pure PI, was tested and compared with a conventional PI based actuator. PI/Al2O3 nanocomposite was prepared by dispersing 13 wt% Al2O3 particles with its grain diameter 20 nm into PI film. Discharge characteristics were measured with a high-voltage probe, current probe and capacitor probe. The performances were evaluated through induced thrust measurement. Then, the surface characteristics were examined using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Experimental results indicate that PI/Al2O3 nanocomposite based actuator consumes higher electrical power and induces higher thrust. The lifetime of PI/Al2O3 nanocomposite based actuator is 4.2 and 2.3 times longer than that of the PI-based actuator at an excitation peak to peak voltage of 8 kV and 10 kV with a fixed frequency of 6 kHz, respectively. FTIR measurement reveals that incorporation of Al2O3 nanoparticles can weaken the absorption sketch intensities. After discharge for 600 min, the PI surface is seriously aged with highly dispersed grooves and protrusions, while the PI/Al2O3 nanocomposite surface is covered by an Al2O3 nanoparticles layer. Furthermore, slightly decrease in oxygen-containing groups measured by XPS suggests that this layer can suppress the surface oxidation and protect the matrix from plasma etching.