A Study of the Aerodynamics of Flexible Wings in Clap and Fling Mechanism
Date Issued
2010
Date
2010
Author(s)
Wang, Hao-Cheng
Abstract
Insects had developed many flying technique through longstanding evolution. In 1973, Weis-Fogh found a novel mode called ”clap-fling mechanism” which can pro-duce high lift. There are many researchers use rigid body to simulate the clap-fling mechanism of two wing configuration. But few considered the flexibility of insect wings and its influence to aerodynamics problem. Therefore, we focus on the high-lift mechanism of wasp Encarsia in this study. Then, we use the rigid airfoil (acrylic) and flexible wings (silica gel) as the experimental wings in order to figure out the reason how does the insect evolve into flexible wing. In the meanwhile, we can investigate the discrepancy of acting force by different flexibility of airfoil, and also discovers each advantage and their shortcoming.
For the experiment setup, we use single-axis robot arms mounted on sevo motors, and simulate the motion of clap and fling in the experimental tank. In order to fit the Reynolds number for real insect flapping, the mixture of water and glycerine was used as the experiment fluid and the Reynolds number is around 90. There are five differ-ent flexibility of airfoil, the motion of clap and fling was set to be symmetric mode, and the attack angle varies from 100 ~ 800 with 100 increment, the Strouhal num-ber St= 0.1~0.5. We can measure the acting force by force sensor for different attack angles to discover the source of high-lift generation during the clap-fling motion. And look into the impact on the wing flexibility for clap-fling mechanism. Moreover, it can compare the lift enhancement between two wings and single wing, and also observe the lift enhancement related to the flexibility of the airfoil.
The results indicated that the flexible wing can produce the same lift as the rigid wing, and the drag force is much smaller than that of the single wing under the same condition. In addition, the performance of lift in average is better for each attack angle. This phenomenon can support advantageous evidence that the insect evolved into flexible wings.
Subjects
Bio-Inspired propulsion
Clap-fling mechanism
Flexible wings
Type
thesis
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