Type of Document Master's Thesis Author Grant, David J Author's Email Address email@example.com URN etd-05072008-133744 Title Full Scale Investigation of Bilge Keel Effectiveness at Forward Speed Degree Master of Science Department Aerospace and Ocean Engineering Advisory Committee
Advisor Name Title McCue-Weil, Leigh S. Committee Chair Etebari, Ali Committee Member Hughes, Owen F. Committee Member Keywords
- bilge keel
- roll damping
- full scale
Date of Defense 2008-04-28 Availability unrestricted AbstractShip motions in a seaway have long been of great importance, and today with advanced hull forms and higher speeds they are as important as ever. While one can now often adequately predict heave, pitch, sway, yaw and even surge, roll motions are much more difficult. Roll is the one motion that is very dependent upon viscous effects of the fluid. Recently, at David Taylor Model Basin, there have been model experiments where the bilge keels were instrumented in order to directly measure their damping force upon the vessel. To build upon this work and to validate it when applied to full scale vessels, a trial using the Italian naval vessel Nave Bettica was performed.
The objective of this thesis is to describe the experiment, present and analyze the results, and offer some conclusions based upon these results. The process of instrumenting the port bilge keel using strain gages and correlating their output to pressures and total forces is described. Selected results for different forward speeds are presented, with full results in the appendices. Particle image velocimetry (PIV) was also performed during the test and was used to measure the flow field in a three foot by three foot area under the aft end of the same bilge keel. Selected image series are presented, as is a methodology for using these images to calculate the center of pressure and the corresponding results.
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