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Eighteenth Symposium on Naval Hydrodynamics (1991) / Chapter Skim
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Wave Devouring Propulsion Sea Trial
Pages 287-296

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From page 287...
... ABSTRACT The development of Wave Devouring Propulsion System and results of it's sea trial are presented in this paper. WDP system is an idea not only for the ship propulsion system which converts wave energy directly into thrust but also the ship motion reduction system.
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From page 288...
... u, v is the wave's vertical and horizontal velocity component plus relative hydrofoil motion due to ship motion and hydrofoil pitch motion in the waves. Thrust is generated as a horizontal component of lift(L)
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From page 289...
... The thrust generation and resistance increase is calculated theoretically. The coefficients of ship motion was calculated by OSM, the hydrodynamics force acting on the hydrofoil is calculated using the quasi-steady theory including the three-dimensional effect.
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From page 290...
... I,, ~ ~=_1 1.0 2.0 3.0 A/J L Fig. 5 Theoretical calculation of the resistance increase in head sea condition(Fn=0.25)
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From page 291...
... Selected design wave height to length ratio is 1/30 and design wave length is 1.6 Lpp of the ship. Taking into the consideration of the actual sea trial using a rather small Vessel, structural design was decided carefully to have enough strength.
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From page 292...
... : Rate Gyro Wave Height : Wave Prove (Drop type) Wind Direction and Speed : Wind Meter Stress of the WDPS arm : Strain Meter Pitch Angle of Foil : Linear Potentio Meter and The test An on board microcomputer was used for data sampling, and at the same time, data were recorded on a data recorder.
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From page 293...
... 0.43 0.40 _ 0.38 January 12th, 1989 we had a good wave condition. The direction of the incident waves and the swell were different all day but in the afternoon, wave height decreased and the swell subsided.
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From page 294...
... (rpm) Fig.14 Results of speed trial in head sea condition.
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From page 295...
... However after the e f f ec t ivene s s o f the hydrofoil was c onf irmed, they willingly tested the WDPS ship in heavy sea conditions where they had never sailed ordinary hydrofoil-less ship at the test speed range. We had a chance to compar e the sat 1 ing test of her sister ship in the same rough sea at the same time.
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From page 296...
... pp.66-78 (73Bessho,M., Kyo~uka,Y., "On the Ship Motion Reduction by Antipitching Fins in Head Seas", 15th Symp. Naval Hydrodynamics, 1985, pp.l09-118 (8)
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Key Terms

  • resistance increase
  • head sea
  • sea condition
  • sea trial
  • pitch motion

  • wave height
  • wave energy
  • propulsive efficiency
  • speed trial
  • ship motion

  • pitch reduction
  • wave period
  • wave devouring
  • ship speed
  • reduction effect

  • speed range
  • wave length
  • calm sea
  • thrust generation
  • devouring propulsion

  • model testing
  • relative flow
  • motion reduction
  • mean wave
  • actual sea

  • length ratio
  • wave condition
  • spring constant
  • engine power
  • ship length


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