Ship Roll Motion Damping Using Bilge Keels – A Detailed CFD Investigation

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Authors
  1. Counsil, J.
  2. McTaggart, K.
  3. Groulx, D.
  4. Goni Boulama, K.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN);Royal Military Coll of Canada, Kingston ONT (CAN) Dept of Mechanical Engineering;Dalhousie Univ, Halifax NS (CAN) Dept of Mechanical Engineering
Abstract
A study has been undertaken to test the value of unsteady Reynolds-averaged Navier-Stokes (URANS) and traditional semi-empirical methods in the face of complex ship roll phenomena, and provide insight into the selection of bilge keel span for varying roll amplitudes. The computational fluid dynamics (CFD) code STAR-CCM+ is employed and two-dimensional submerged bodies undergoing forced roll motion are analyzed. The spatial resolution and timestepping scheme are validated by comparison with published numerical and experimental studies. The model is then applied to a fully-submerged circular cylinder with bilge keels of varying span and undergoing roll motion at varying angular amplitudes. Extracted hydrodynamic coefficients indicate that in general, increasing displacement amplitude and bilge keel span yields increased added mass and increased damping. The relationship is complex and highly dependent upon vortex interactions with each other and the body. The semi-empirical methods used for comparison yield good predictions for simple vortex interactions but fail where viscous effects are strong. Hence, URANS methods are shown to be necessary for friction-dominated flows while semi-empirical methods remain useful for initial design considerations.
Keywords
ship hydrodynamics;bilge keel;roll damping;added mass;URANS;submerged body
Report Number
DRDC-RDDC-2015-P186 — External Literature
Date of publication
17 Feb 2016
Number of Pages
14
DSTKIM No
CA041991
CANDIS No
803192
Format(s):
Electronic Document(PDF)

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