2026-09-18T23:37:11Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/334352022-01-13T07:54:39Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Paul D. Sclavounos and Ahmed F. Ghoniem.
Tozzi, Gregory Michael
Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Department of Ocean Engineering
2006-07-13T15:24:09Z
2006-07-13T15:24:09Z
2004
2004
http://hdl.handle.net/1721.1/33435
62868941
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 100).
A study was carried out to develop and test techniques for the computational optimization of hydrofoil sections and lifting surfaces advancing under a free surface. A mathematical model was developed based on the extension of a two-dimensional potential flow solution to account for three dimensional effects. Prandtl's lifting line theory was used to account for induced drag and downwash at the leading edge of the foil. Strip theory was used to extend the two-dimensional wave drag solutions to three dimensions for high aspect ratio foils. A semi-empirical correction was added to account for viscous drag. The drag-to-lift ratio of foil sections and lifting surfaces were optimized using first order gradient techniques. Optimization studies involving submerged foil sections suggest that trading buoyancy for a reduction in wave drag will lead to optimal geometries. Difficulties encountered resulting from the adoption of a potential flow model were identified and discussed. The lifting surface optimization was carried out using the coefficients of Glauert's circulation series as design variables. At high speeds it was shown that non-elliptical loading can produce reductions in the drag-to-lift ratio of a lifting surface. Induced drag dominated the low-speed optimization, and elliptical loading was shown to be optimal at the low end of expected operating speeds of a hydrofoil vessel. An adjoint formulation for the problem of optimizing the shape of a lifting section under a free surface was derived for use in future research.
by Gregory Michael Tozzi.
S.M.
125 p.
4618128 bytes
4623330 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
Ocean Engineering.
Mechanical Engineering.
Hydrofoil shape optimization by gradient methods
Thesis
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