Fluid Dynamic Comparison of 3 Sailboat Keels

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Fluid Dynamic Comparison of 3 Sailboat Keels

• Presented by JR Fowler
• Advisor Prof. Anderson
• Mer 197
• 11/8/01

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Outline

• Introduction and Objective
• Background on the Fundamentals of Sailing
• Keel Selection
• Making of Models
• Testing Options
• Goals for Next Term and Conclusion

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Introduction and Objective

• Sailing since age 6
• Link love of Sailing with Senior Project
• Interest in PIV
• Compare 3 different keels
• Lift/Drag
• PIV
• Losses under keel

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Background on the Fundamentals of Sailing

• Hull
• Sails
• Keel
• Why boats can move into the wind

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Hull

• Boat must float
• Displacement greater then weight of boat
• Shape also pulls boat forward by extending keel
  vorticity
• Avoid Boundary layer separation
• Reduce Drag

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Sails

• Bernoulli's equation
• Minimum angle of attack of 40 deg TW.
• Sail affected by apparent wind
• Vector summation of boat and wind
• Allows boat to sail faster then true wind in some
  scenarios

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Keel

• Righting moment for boat
• Limit sideways movement known as slip
• Create lift to drive boat into direction of wind
• Creates minimal lift after 135 deg.

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Why Boats Move Forward
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Keel Selection

• Fin Keel
• Bulb Keel
• Modified Bulb Keel
• Model taken at Brewers Yacht Yard Stamford CT

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Keel Selection
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Keel Selection
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Make Models

• Measured keels using calipers, string and tape
• Attempted to use Visualization Equipment
• Make keel models on SolidWorks
• Current position of project
• Possibly get Designer Data

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Rapid Prototyping

• Make model from CAD file
• Stererolithography, powder sintering, rapid
  deposition molding
• 3 days to make
• Precision of 0.0004 of an inch
• Laser solidifies liquid spot by spot and drops
  level by 1/500 of an inch

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Options of testing

• Wind Tunnel
• Water Tunnel
• Neither required velocities are achievable
• As long as constant velocities comparison ok but
  not a true representation

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Goals for Next Term and Conclusion

• Get Models Made
• Lift - Drag Analysis
• PIV Analysis
• Vorticity
• View of losses of pressure beneath keel
• Successful first term, on schedule
• Adapted well to changes

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Questions?