Visualization of flow around a flapping machine imitating an insect's flight

The purpose of this research is to clarify generation mechanism of aerodynamic force of flapping airfoil imitating insect's flight. Hovering flights are important to develop micro air vehicles (MAV) for rescue inquiry devices of disaster area. In order to understand hovering flight of insects, aerodynamic lifting force and flow field around a flapping machine was measured by using PIV and numerical simulation. PIV measurements were carried out with the flapping machine which was 10 times expanding model of real insects. Experimental results showed a flapping-airfoil holds a strong vorticity near the bottom dead center. The wake-capture process can be observed by the PIV measurement, which is important to understand insect's flight. Moreover these processes generate large amount of aerodynamic force compare to the sinusoidal flapping motion. It reveals that feathering motion is important to realize the hovering flight.