Active Flow Control by Shape-morphing Airfoil under Low Reynolds Turbulent Flow and Gust Disturbances
Abstract
Interest in the study of low Reynolds aerodynamics has increased in recent years, primarily due to technological advancements in the development of vehicles that operate within this flow regime, such as UAVs and MAVs. Challenges arise from the application of conventional wing designs to these vehicles, where aerodynamic performance diminishes. Furthermore, they are significantly influenced by disturbances within the atmospheric boundary layer, including turbulence and wind gusts, which induce abrupt and unpredictable changes in the incident flow, affecting trajectory and flight performance. These challenges led to the development of mechanisms capable of mitigating the negative effects, particularly inspired by the study of bird and insect flight, where enhanced aerodynamic performance and rejection of atmospheric disturbances have been observed. One approach to address these challenges involves utilizing shape-morphing wing as an Active Flow Control (AFC) system, varying the aerodynamic airfoil geometry in response to specific signals. This type of system allows for dynamically modifying the flow field around the airfoil as needed, requiring minimal energy consumption. However, the phenomenon involves complex unsteady aerodynamic mechanisms, which are still under study and unresolved. This research aims to experimentally analyze the aerodynamic effects generated by an AFC system through shape-morphing, under various low Reynolds flow conditions including different turbulence levels and wind gust disturbances, such as those encountered in real air vehicle atmospheric conditions. To achieve this, the system will be constructed, characterized, and analyzed under different conditions, aiming to evaluate and quantify its effects on efficiency ratios and as a mechanism for disturbance rejection. The observation of bird flight showed that they use shape-morphing wings to adapt to changing flight conditions, allowing them to reject wind gusts in flight and maintain their orientation and trajectory. This ability is based on two mechanisms implemented by these animals- an inertial mechanism caused by wing elevation, and an unsteady aerodynamic mechanism achieved through wing morphing to momentarily reduce the load generated by the gust (Chenet et al., 2020). Conceptually, the latter can be achieved by directly reducing the angle of attack through wing orientation changes, or, alternatively, by transiently reducing the net curvature of the airfoil to limit lift generation. However, research conducted on gust rejection is limited, being an area that requires further development. The research will enhance our understanding of the physics involved in an area that has seen limited advancement and will improve understanding of gust rejection phenomena observed in bird flight, with potential applications to MAVs and UAVs.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410289
Entities
People
- Julio Maranon Di Leo
Organizations
- Air Force Office of Scientific Research
- United States Air Force