Analysis of non-symmetrical flapping airfoils |
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Authors: | W B Tay K B Lim |
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Institution: | (1) Department of Mechanical Engineering, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, Singapore |
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Abstract: | Simulations have been done to assess the lift, thrust and propulsive efficiency of different types of non-symmetrical airfoils
under different flapping configurations. The variables involved are reduced frequency, Strouhal number, pitch amplitude and
phase angle. In order to analyze the variables more efficiently, the design of experiments using the response surface methodology
is applied. Results show that both the variables and shape of the airfoil have a profound effect on the lift, thrust, and
efficiency. By using non-symmetrical airfoils, average lift coefficient as high as 2.23 can be obtained. The average thrust
coefficient and efficiency also reach high values of 2.53 and 0.61, respectively. The lift production is highly dependent
on the airfoil’s shape while thrust production is influenced more heavily by the variables. Efficiency falls somewhere in
between. Two-factor interactions are found to exist among the variables. This shows that it is not sufficient to analyze each
variable individually. Vorticity diagrams are analyzed to explain the results obtained. Overall, the S1020 airfoil is able
to provide relatively good efficiency and at the same time generate high thrust and lift force. These results aid in the design
of a better ornithopter’s wing. |
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Keywords: | Flapping Non-symmetrical Design of experiments Ornithopter Airfoil |
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