Title page for ETD etd-05072008-133744


Type of Document Master's Thesis
Author Grant, David J
Author's Email Address davegrant28@gmail.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
Abstract
Ship 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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