**5. Conclusion**

In the present study, we report the research progress made in our efforts to utilize the thermal effects induced by DBD plasma actuation to suppress dynamic ice accretion process over the surface of an airfoil/wing model for aircraft icing mitigation. While the fundamental mechanisms for thermal energy generation in DBD plasma actuation were introduced briefly, the significant differences in the working mechanism of the DBD-plasma-based surface heating approach from those of conventional resistive electric heating methods were highlighted for aircraft anti−/de-icing applications. By leveraging the unique Icing Research Tunnel available at Iowa State University (*i.e.*, ISU-IRT), a comprehensive experimental campaign was conducted to quantify the thermodynamic characteristics of an DBD plasma actuator embedded over the surface of an airfoil model exposed to frozen cold incoming airflow coupled with significant convective heat transfer in the context of aircraft anti−/de-icing. By integrating a DBD plasma actuator and a conventional electrical film heater onto the same airfoil/wing model, an experimental investigation was conducted to provide a side-by-side comparison between the DBD plasma-based approach and conventional resistive electrical heating method in preventing ice formation and accretion over the airfoil surface under a typical aircraft icing condition. While a high-speed camera was used to capture the transient details of the dynamic ice accretion and water transport processes over the airfoil surface, an infrared (IR) thermal imaging system was utilized to map the corresponding temperature over the airfoil surface protected by the DBD plasma actuator and the electrical film heater during the anti−/de-icing operation. Based on the side-by-side comparison of the measurement results (*i.e.*, snapshots of the visualization images and quantitative surface temperature distributions) on the plasma side of the airfoil surface against those of the electric film heater side under the same icing test condition, the effectiveness of using the thermal effects induced by DBD plasma actuation and the conventional electrical heating in preventing ice formation and accretion over the airfoil surface was evaluated and analyzed in details.

It was found that, with the same input power density, the surface temperature on the electric film heater was much higher than that over the surface of the DBD plasma actuator before the water droplets impingement, which was essentially due to the different heating mechanisms of the two methods. For the conventional electrical film heater, the thermal energy was mainly generated at the heater surface. For the case of the DBD plasma actuation, the heating path is through heat transfer from the plasma discharges to the ambient gas at first, and then heating up the surfaces of the dielectric layer and electrodes through direct injection, convection, and radiation. Upon the impingement of the super-cooled water droplets onto the airfoil surface, while the surface temperature over the electrical film heater was found to descend significantly due to the instant heat transfer from the electric film heater surface to the impinged water mass, the decrease in the measured surface temperature over the airfoil surface on the plasma actuator side appeared to be much less since the airborne water droplets were pre-heated greatly as flying through the hot air above the DBD plasma actuator before being in contacting with the heated airfoil surface. As a result, the DBD plasma-based method showed a more promising performance in preventing ice formation and accretion over the airfoil surface, in comparison with that of the conventional electrical heating method.

*An Experimental Investigation on the Thermodynamic Characteristics of DBD Plasma… DOI: http://dx.doi.org/10.5772/intechopen.100100*

An explorative study was also conducted to further improve the anti−/de-icing performance of the DBD plasma-based method by adopting a duty-cycle modulation concept. It was found that the implementation of duty-cycled modulation to the DBD plasma actuation can significantly enhance the thermal effects induced by the DBD plasma actuation. It was demonstrated clearly that, under the same icing condition and the same total power input, the duty-cycled plasma actuation has a better anti−/de-icing performance in comparison to the continuous plasma actuation. The findings derived from the present study could be used to explore/optimize design paradigm for the development of novel DBD-plasma-based anti−/de-icing strategies tailored specifically for aircraft icing mitigation.
