2026-09-19T02:39:59Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/356362022-01-13T07:54:36Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Alexandra H. Techet.
Read, Melissa B. (Melissa Beth), 1982-
Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
2007-01-10T16:53:46Z
2007-01-10T16:53:46Z
2006
2006
http://hdl.handle.net/1721.1/35636
76701534
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.
Includes bibliographical references (p. 133-135).
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.
(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.
by Melissa B. Read.
S.M.
135 p.
5718806 bytes
5724422 bytes
application/pdf
application/pdf
eng
Massachusetts Institute of Technology
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.
http://dspace.mit.edu/handle/1721.1/7582
Mechanical Engineering.
Performance of biologically inspired flapping foils
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="6100dec3-deda-4f91-bfc1-fefd376790c3">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Performance of biologically inspired flapping foils</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2006</PublicationDate>
<Authors>
<Author>
<DisplayName>Read, Melissa B. (Melissa Beth), 1982-</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Mechanical Engineering.</Keyword>
<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.</Abstract>
<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.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>