Experimental investigations on thermodynamic characteristics of DBD plasma and applications for aircraft icing mitigation

Aircraft icing is widely recognized as a significant hazard to aircraft operations. When an airplane flies in a cold climate, some of the super-cooled droplets will impact and freeze on exposed airframe surfaces to form ice shapes. Ice accumulation can degrade the aerodynamic performance of an airplane significantly by increasing drag while decreasing lift. In moderate to severe conditions, an airplane can become so iced up that continued flight is impossible. While a number of anti-/de-icing systems have been developed for aircraft inflight icing mitigation, current anti-/de-icing strategies suffer from various drawbacks, including being too complex, too heavy or draw too much power to be effective. Very recently, dielectric barrier discharge (DBD) plasma actuation has been suggested as a promising, alternative anti-/de-icing method, by leveraging the thermal effects induced by DBD plasma generation. In the present study, a comprehensive study was conducted to examine the thermodynamic characteristics of DBD plasma with the intention to explore its potential as an effective anti-/de-icing method for aircraft icing mitigation. The experimental study was performed in the unique Iowa State University Icing Research Tunnel (i.e., ISU-IRT). A NACA 0012 airfoil/wing model embedded with DBD plasma actuators was designed and installed in ISU-IRT under typical glaze-/rime icing conditions pertinent to aircraft inflight icing phenomena. During the experiments, the dynamic ice creation process and corresponding surface temperature over the airfoil surface were captured by using a high-speed imaging system and an infrared (IR) thermal imaging system. The thermal effects of Alternative Current DBD (i.e., AC-DBD) plasma actuators were compared quantitatively with conventional electric film heater, and the AC-DBD plasma-based anti-icing methods were found to be at least as effective as, if not better than the conventional electrical heaters in preventing ice formation and accretion over the surface of the airfoil/wing model. In addition, thermal characteristics and anti-icing performance of nanosecond-pulsed DBD (NS-DBD) plasma actuator were also investigated under different icing situations. Surface heating during NS-DBD plasma actuation was found to be strongly affected by environmental and operational conditions. The anti-icing performance of NS-DBD plasma actuation would be improved with increasing pulse repetition frequency. Furthermore, configuration of the plasma-based anti-icing system was optimized to improve efficiency of the icing mitigation. Streamwise employed plasma actuators can increase the heat dissipation to downstream of the airfoil to reduce the rivulet formation. Additionally, a hybrid anti-icing approach was introduced by combining NS-DBD plasma actuators and superhydrophobic surface. NS-DBD plasma actuator employed on an airfoil surface can successfully prevent ice formation at the leading edge, while superhydrophobic coating avoids runback water to freeze on surface and form ice rivulets. The findings derived from the present study are very helpful to elucidate the underlying physics and to explore/optimize design paradigms for the development of effective and robust plasma-based anti-/deicing strategies to ensure safer and more efficient operation of aircraft in cold weather