Anti-icing performance using the surface dielectric barrier discharge plasma actuator is studied using detailed visualization and surface thermal measurements. To reveal the physical mechanism of coupled aerodynamic and thermal effects on anti-icing, three types of actuators are designed and mounted on a NACA 0012 airfoil. The coupled aerodynamic and thermal effects are confirmed in still air. The results show that the plasma actuation is effective for in-flight anti-icing, and the anti-icing performance is directly related to the design of the plasma actuators based on the coupled aerodynamic and thermal effects. When the direction of plasma induced flow is consistent with the incoming flow, the heat generated by plasma discharge is concentrated in the region of the actuator and the ability of the actuator for heat transfer downstream is relatively weak during the anti-icing. When the induced flow is opposite to the incoming flow, there is less heat accumulation in the actuator region, while the ability of heat transfer downstream becomes stronger. With the consistent and opposite direction of induced flow, the plasma actuation can ensure that 57% and 81% chord of the lower surface of the airfoil are free of the ice accumulation, respectively. Another actuator is designed to induce the air jets approximately perpendicular to the airfoil surface. This exhibits both a stronger ability of heat accumulation locally and heat transfer downstream and hence ensures that there is no ice on the entire lower surface of the airfoil.

A field campaign was carried out to investigate ice accretion features on large turbine blades (50 m in length) and to assess power output losses of utility-scale wind turbines induced by ice accretion. After a 30-h icing incident, a high-resolution digital camera carried by an unmanned aircraft system was used to capture photographs of iced turbine blades. Based on the obtained pictures of the frozen blades, the ice layer thickness accreted along the blades’ leading edges was determined quantitatively. While ice was found to accumulate over whole blade spans, outboard blades had more ice structures, with ice layers reaching up to 0.3 m thick toward the blade tips. With the turbine operating data provided by the turbines’ supervisory control and data acquisition systems, icing-induced power output losses were investigated systematically. Despite the high wind, frozen turbines were discovered to rotate substantially slower and even shut down from time to time, resulting in up to 80% of icing-induced turbine power losses during the icing event. The research presented here is a comprehensive field campaign to characterize ice accretion features on full-scaled turbine blades and systematically analyze detrimental impacts of ice accumulation on the power generation of utility-scale wind turbines. The research findings are very useful in bridging the gaps between fundamental icing physics research carried out in highly idealized laboratory settings and the realistic icing phenomena observed on utility-scale wind turbines operating in harsh natural icing conditions.