Research progress on the wind tunnel experiment of a bionic flapping-wing aerial vehicle

“Flapping wing” is a mechanism observed in the flight of birds, insects, and bats. The lift and thrust for a flight are generated by the active movement of wings. It was first specifically designed by Da Vinci. With good concealment and maneuverability advantages, the bionic flapping wing has become the hotspot in the field of aerial vehicles at home and abroad in recent years. Due to its high degree of bionic appearance and ultra-low flight noise, the bionic flapping-wing aerial vehicle has important applications in the military and civilian fields. Because of a low Reynolds number, unsteady aerodynamics, and other issues, such as flexible deformation of the wing and so on, the study of a bionic flapping-wing aerial vehicle is quite different from that of a conventional fixed-wing aerial vehicle. The three methods used in the study of a flapping-wing aerial vehicle are aerodynamic calculations, wind tunnel experiments, and outside flight tests. In terms of aerodynamic calculation, the theory and method of an unsteady aerodynamic design and optimization are still inadequate at present. The outside flight test cannot accurately measure the complex aerodynamic force of the aerial vehicle and cannot conduct quantitative analysis as well as research on the aerial vehicle. As the wind tunnel experiment can simulate a real flight, the data obtained is more reliable, can be analyzed, and studied quantitatively. Therefore, the wind tunnel experiment has become an effective method to study a flapping-wing aerial vehicle. Researchers at home and abroad have conducted several experimental studies on a bionic flapping-wing aerial vehicle using a wind tunnel. This paper first introduced the composition and classification of a wind tunnel and then introduced the research status of the wind tunnel experiment, covering the bird-like and insect-like flapping-wing aerial vehicles in detail. Finally, this paper provided suggestions on the possible research directions to the wind tunnel experiment of the bionic flapping-wing aerial vehicle, such as research on how the multi-wing and the feather structure of the wings affect the performance of the bionic flapping-wing aerial vehicle.