Experimental study on the flow speed effects on the aerodynamic characteristics of a flexible flapping wing

Document Type : Research Article

Authors

1 Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran

2 Department of Aerospace Engineering,, Amirkabir University of Technology, Tehran, Iran.

Abstract

The current research has experimentally studied the aerodynamic characteristics and production of lift and thrust forces of a flapping flexible wing over a range of flow speeds and frequencies in the sub-sonic wind tunnel. Thus, the flapping wing model was installed on the test section, and by changing the flow components and angles of attack, the horizontal and vertical forces - equivalent to the thrust and lift - were measured and recorded. The experiments were conducted at Reynolds numbers of 42,000 to 170,000, which is the flight range for natural birds with dimensions close to pigeons. The wingbeat frequency has also been set from 0 to 6 Hz to encompass the wingbeat frequency of natural birds. The model consists of two parts of rigid (at the root) and flexible (at the tip) and the oscillation is provided by an electro-mechanical system.  The highest thrust was achieved at an angle of attack of 3 degrees. The wing flexibility caused the pressure difference on both sides of the wing to cause unsteady deformations. In this case, as the speed increases, the amount of lift on the wing grows with the square power of the speed, Thus, the wing deforms more at higher speeds and the lift coefficient decreases with increasing speed. The flow structure at an angle of attack of 9 degrees is not capable of producing thrust.

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References

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Amirkabir Journal of Mechanical Engineering
Volume 56, Issue 11
February 2025
Pages 1497-1516

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