Wind Tunnel Experimental Investigation on the Gust Response Characteristics of Mav
|School||Nanjing University of Aeronautics and Astronautics|
|Keywords||Micro Air Vehicle(MAV) Flexible Wing Horizontal Gust Dynamic Aerodynamic Characteristics PIV|
The gust is the most important factor that affects the Micro Air Vehicle (MAV) flight safely and steadily. The gust response characteristics of a biplane MAV are studied at first. A data processing method which could be applied on the dynamic data is given. Then a rigid wing MAV and a flexible wing MAV of a flying wing configuration are designed and fabricated. The longitudinal and lateral aerodynamic characteristics of the two MAVs in steady flow field are studied. The results show that the effect of Reynolds number on flexible wing is greater than that on rigid one. The flexible wing can increase the stall angle of attack. At the same time, it has better lateral stability. The unsteady aerodynamic characteristics of the two MAVs in horizontal gust are studied. Both the effects of the angle of attack of the two MAVs and the oscillating frequency of velocity are discussed. The results show that the aerodynamic characteristics of the two MAVs are changed with the free stream accelerating and decelerating, especially in large incidence and large oscillating frequency. When the incidence and oscillating amplitude of velocity are constant, the oscillation of the aerodynamic characteristics is increased with the oscillating frequency of velocity in large angle of attack. The comparison of the aerodynamics characteristics in gust between the two MAVs is discussed. The results show that the flexible wing can improve flight quality. It has the ability of delaying stall and alleviating the effects of gust which benefit to safe and steady flight. At last, the flow field is measured with PIV. The results show that the position and the intensity of the tip vortices on the flexible wing is different from that of the rigid wing in span direction. The flexible wing delays the separation. All these lead to their different flow structures on flexible wing. Because the response of different flow structure to free stream accelerating and decelerating is different, the unsteady aerodynamic characteristics are different between the two MAVs.