Rotary Wing Aerodynamics

Rotary wing aerodynamics represents a widely investigated topic due to this discipline’s large number of applications in several fields of engineering and physics. Indeed, rotating lifting bodies provide quite complex and unsteady flow structures that have a robust influence in rotorcraft, aeronautical propulsion, turbomachinery and wind energy fields. Consequently, a deep knowledge of the main classical phenomena related to rotary wing aerodynamics, such as dynamic stall or blade–vortex interactions (BVI), to cite a few, is an essential step to improving the performance of helicopters or wind turbines.
In recent years, research effort in the field of rotary wing aerodynamics was focused on the study of rotor–rotor and rotor–body aerodynamic interactions. This interest was influenced in the aeronautical field by the recent great development efforts devoted to the design of unconventional vertical take-off and landing (VTOL) aircraft for urban air mobility (UAM). Indeed, recent improvements in electric motors and battery technologies present an opportunity for new concepts of personal aviation that will provide benefits to ground traffic in overcrowded metropolitan areas and will also improve the performance of logistics services. Distributed electric propulsion represents a key feature in the design of these new VTOL air vehicles, well-known as eVTOLs. Their architecture is characterised by multirotor and multi-wing configurations that highlight unprecedented aerodynamics challenges with respect to classical aircraft or rotorcraft configurations. Indeed, the occurrence of several different interactional effects between propellers and lifting bodies has a profound impact on aircraft performance and noise impact. Thus, a deeper understanding of the complex interactional aerodynamics features characterising eVTOL vehicles represents a milestone to be achieved before the next-generation UAM aircraft can soar through the skies of our metropolitan areas. In recent years, the field of wind energy research has also paid great attention to the phenomena of rotor–rotor interactional aerodynamics due to the great effort spent on the development of wind farms. Indeed, a thorough understanding of the complex aerodynamic interactions occurring between wind turbine wakes or the study of effective wake redirection techniques can be considered essential key points to improve power capture and reduce structural loading for wind farms application.