Development of Autonomic Micro Air Vehicles with mechanical flapper

点击翻译按钮获取中文摘要

The purpose of this investigation is to develop Micro Air Vehicles with mechanical flapper like flying insects. Since insects use a low-Reynolds number effect and changing flow properties, the insects' flight is different from the flight of man-made airplane wings. In order clarify the aerodynamic properties of flying insects, aerodynamic forces and flow fields were measured by a micro load cell system and a dynamic PIV system. As a result, the feathering angles of flapping airfoils are important in generating a vertical force with a flapping wing. The experimental result showed the simple U-shaped separation occurs in flow around a dragonfly. The U-shaped separation is one of the simplest analytical solutions of the Navier-Stokes equation in dynamic stall flow over a wing. These vortex tubes play an important role in the aerodynamic force generated by the flapping wings of insects.Moreover, we attempted to develop a mechanical flapper for MAV based on these experimental results.Light-weight wings were manufactured with MEMS technologies. The weight and stiffness of developed wings are almost same as real insects. The averaged lifting force of the mechanical flapper was same order of aerodynamic force of real insects. The experimental results also showed the lifting force was proportional to the second power of the flapping frequency. The developed mechanical flapper generated large aerodynamic force when the feathering angle was set to suitable angle. However it was not enough to lift up the mechanical flapper. Because of the total weight of the mechanical flapper was 10 times larger than that of the real insects. The result indicated that the flapping frequency was necessary for 40.8 Hz to lift up the machine. The developed mechanical flapper had a potential of the hovering flight. Now, we are making up the modified mechanical flapper which flapping frequency is over 50 Hz.