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Performance of biologically inspired flapping foils

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dc.contributor.advisor Alexandra H. Techet. en_US Read, Melissa B. (Melissa Beth), 1982- en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Mechanical Engineering. en_US 2007-01-10T16:53:46Z 2007-01-10T16:53:46Z 2006 en_US 2006 en_US
dc.description Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. en_US
dc.description Includes bibliographical references (p. 133-135). en_US
dc.description.abstract Flapping foil propulsion is thought to provide AUVs with greater maneuverability than propellers. This thesis seeks to simplify the design process for this type of propulsion system by identifying thrust and wake characteristics for flapping foils and determining how these factors scale with certain parameters. First, the wake of a flapping NACA 0030 foil was studied qualitatively using fluorescent dye visualizations. The foil was heaved and pitched in a sinusoidal fashion. The effects of varying Reynolds number, Strouhal number, maximum pitch angle, and the phase shift between heave and pitch were studied. It was determined that at very low Strouhal numbers the wake was 'S' like and at moderate Strouhal numbers the wake contained discreet horseshoe-like vortices. Next, the wake was studied quantitatively using particle image velocimetry (PIV). Through this technique, numerical thrust coefficients and vorticity strengths were obtained as well as qualitative information regarding the morphology of the wake. The coefficient of thrust peaked at a different Strouhal number for each Reynolds number studied. This trend was compared to natural phenomenon. en_US
dc.description.abstract (cont.) Impulsively started maneuvers were also studied using PIV. Both single flaps and half flaps of the foil were studied. It was determined that impulsively started single flaps produced a much larger maximum coefficient of thrust than the impulsively started half flaps. Many of the experiments were repeated using a biologically inspired trout tail shaped foil. en_US
dc.description.statementofresponsibility by Melissa B. Read. en_US
dc.format.extent 135 p. en_US
dc.format.extent 5718806 bytes
dc.format.extent 5724422 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.subject Mechanical Engineering. en_US
dc.title Performance of biologically inspired flapping foils en_US
dc.type Thesis en_US S.M. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Mechanical Engineering. en_US
dc.identifier.oclc 76701534 en_US

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