Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 53 Issue 3 (Special Issue) 2021 05 22 Experimental investigation of the effect of flapping on the lift and thrust forces of 3D-wing Experimental investigation of the effect of flapping on the lift and thrust forces of 3D-wing 1697 1708 4358 10.22060/mej.2021.15292.6090 FA Mojtaba Ramezani Voloojerdi Aerospace Engineering Department, Amirkabir University of Technology, Tehran, Iran 0009-0001-0146-4945 Mahmoud Mani Aerospace Engineering Department, Amirkabir University of Technology, Tehran, Iran Journal Article 2018 11 18 Effects of flapping on lift and thrust forces in a 3D flapping wing have been investigated at low Reynolds numbers and several reduced frequencies, using experimental tests in a subsonic wind tunnel. Tests have been performed at Reynolds numbers 42000 to 170000 and reduced frequencies 0 to 0.45 that most birds flight at this ranges. Also, the ranges of the angle of attacks are between 0°-24°. Results have shown that an increase of reduced frequency can enhance the lift force by up to 100 percent and in some cases reduce drag force to zero. Furthermore, increment of reduced frequency has caused a delay in stall of the wing. Also by increasing the Reynolds number from 42000 to 86000, the major region of the boundary layer of the wing surface becomes turbulent, so maximum lift force increases by 40 percent. Wind tunnel test results show that the effect of reduced frequency on the lift force was dependent on the angle of attack, so at the lower attack angles, the increase of reduced frequency did not affect the lift coefficient, but, with increment in the angle of attack, the positive effect of the reduced frequency on the coefficient of the lift force increased. Effects of flapping on lift and thrust forces in a 3D flapping wing have been investigated at low Reynolds numbers and several reduced frequencies, using experimental tests in a subsonic wind tunnel. Tests have been performed at Reynolds numbers 42000 to 170000 and reduced frequencies 0 to 0.45 that most birds flight at this ranges. Also, the ranges of the angle of attacks are between 0°-24°. Results have shown that an increase of reduced frequency can enhance the lift force by up to 100 percent and in some cases reduce drag force to zero. Furthermore, increment of reduced frequency has caused a delay in stall of the wing. Also by increasing the Reynolds number from 42000 to 86000, the major region of the boundary layer of the wing surface becomes turbulent, so maximum lift force increases by 40 percent. Wind tunnel test results show that the effect of reduced frequency on the lift force was dependent on the angle of attack, so at the lower attack angles, the increase of reduced frequency did not affect the lift coefficient, but, with increment in the angle of attack, the positive effect of the reduced frequency on the coefficient of the lift force increased. https://mej.aut.ac.ir/article_4358_e8432fb72c61c9066957124e5a420a05.pdf