Lift and drag characteristics of flexible pitching and heaving wings Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/ws859k045

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  • There is a pressing need for Micro Air Vehicles (MAV) that are light, powerful, and efficient to perform military reconnaissance missions and search and rescue operations. These MAVs have length scales on the order of 10 cm, where traditional steady flight wing designs perform poorly. An alternative flight mechanism is the unsteady flapping employed by birds, bees, and insects. This unsteady motion has been shown to be more effective in generating lift and reducing drag forces. Current research into unsteady flapping flight has been primarily focused on the translational heaving and rotational pitching motion of rigid wings. The purpose of this research is to investigate how the kinematics of flapping wings of variable trailing edge flexibility affect flight performance as measured by lift and drag. To investigate this a custom built motion apparatus was used to pitch and heave the wings over a range of conditions. The forces on these wings were measured with a pair of load cells attached to the base of the pitching and heaving device that capture the axial and normal loads on the wing. The effect of changing the non-dimensional heaving amplitude, non-dimensionalized by the chord length, was found by changing the amplitude of the translational heaving motion. Similarly, the pitching amplitude was tested over a range of conditions from non-pitching to pitching with an amplitude of 20 degrees. The central angle that the wing pitched about was advanced from -20 degrees to 20 degrees to explore the role of average angle in unsteady flapping flight. The frequency of the pitching and heaving motion was increased from 0.25 Hz to 0.625 Hz. The major findings from this research are that the Lift/Drag ratio increased with an increase in pitching amplitudes for all flexibilities. The moderately flexible wing performed best for all central angles, with the peak lift occurring when the central angle was at its maximum. The Lift/Drag ratio peaked for a central angle of zero, as the drag was at its minimum. Increasing the heaving amplitude caused slight decreases in lift and drag forces. The reduced frequency decreased the lift and the drag slightly. For all trials the effect of flexibility was small compared to the effect of kinematics.
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  • description.provenance : Made available in DSpace on 2014-07-01T21:24:08Z (GMT). No. of bitstreams: 2 license_rdf: 1223 bytes, checksum: d127a3413712d6c6e962d5d436c463fc (MD5) RushenJesseI2014.pdf: 2510524 bytes, checksum: a4f72c41991451adb72d9b4bdde26680 (MD5) Previous issue date: 2014-06-09
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  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2014-07-01T21:24:08Z (GMT) No. of bitstreams: 2 license_rdf: 1223 bytes, checksum: d127a3413712d6c6e962d5d436c463fc (MD5) RushenJesseI2014.pdf: 2510524 bytes, checksum: a4f72c41991451adb72d9b4bdde26680 (MD5)

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