抄録
The flapping styles of dragonflies in horizontal free flight and at take-off from a vertical wall surface were observed and analyzed with a high-speed video camera. Also, a dragonfly was set in a wind tunnel and flow states generated by flapping of wings were visualized by smoke flow. The results represented the facts that when the wings were flapping with amplitude of about 50-80 degrees, the flow upstream of the body was sucked into the lower pressure region around the body, and in the wake, convex protuberance and concave depressions are brought about on its boundary of the wake. Moreover, when the wings are flapping with amplitude of 3-5 degrees, a mushroom type of vortex was brought forth behind the wings.
