Hydrodynamics of High Speed Craft

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Hydrodynamics of High Speed Craft Dr. D.A.
Hudson, Professor A.F. Molland School of
Engineering Sciences, Ship Science, University of
Southampton. London Branch RINA 17th March, 2006
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Motivation

• To improve ship design, safety and operation
  through a better understanding of ship
  hydrodynamics
• Resistance and propulsion
• Wave wash
• Ship motions
• Human factors very high speed

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Components of Design

• Hull form calm R, added R, motions
• Hydrostatics, stability, damaged stability,
  flooding
• Hydrodynamics resistance and propulsion,
  motions, steering
• Structures, materials
• Machinery Propulsion and auxiliary outfit
• Safety, regulations
• GA
• Design for operation, safety, production, scrap,
• environment, sustainability

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Resistance components

• Resistance components
• Total Hull Resistance Viscous Wave
• Monohulls
• Catamarans
• ? and ? are hull interaction coefficients

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Models

• Model hull forms
• Vary hull form
• Vary separation of hulls
• Also test as monohull

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Wave resistance

• Wave resistance measurement
• Wave probes in tank drive model past

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Wave resistance
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Viscous resistance

• Viscous resistance measurement
• Total viscous and viscous interaction from
  viscous wake traverse in tank
• Viscous interaction from wind tunnel tests and
  CFD analysis

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Viscous resistance
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Viscous resistance
VISCOUS RESISTANCE
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Aerodynamic resistance
AERODYNAMIC RESISTANCE
Wind tunnel tests generic shapes
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Aerodynamic resistance
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Wave wash

• Generated by ship
• Propagated to shore (with decay)
• Impact on safety (e.g. beaches, small craft)
• Impact on environment (coastal erosion, plants,
  animals, etc.)

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Wave wash

• Need to estimate ship waves
• Influence of hull form/type
• Speed
• Shallow water effects
• Estimate size of waves at shore
• Possible limits on wave heights (or energy)
• Passage plans, shallow water, critical speeds

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Wave wash
Sub-critical
Supercritical
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Wave wash
WASH
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Wave wash
Comparison of wave profiles
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Wave wash
H ? y-n n0.5 transverse n0.33 diverging n0.2,
0.4 shallow
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Wave wash
Critical speed - water depth relationship
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Wave wash
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Ship motions

• Pitch, heave, roll, accelerations
• (yaw, sway, surge)
• Safety strength, cargo, crew, passengers
• Comfort motion sickness

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Ship motion analysis - overview
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Ship motions - models

• Model hull forms
• Vary hull form L1.6m, L4.5m
• Vary separation of hulls S/L0.2, 0.4
• Vary heading to waves
• Fn0.2, 0.53, 0.65, 0.80
• Also test as monohull

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Ship motions
Measurement of motions model scale
NPL 5b, S/L0.2, Fn0.65 head seas (180 deg)
NPL 5b, S/L0.4, Fn0.65 oblique seas (150 deg)
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Ship motions
Measurement of motions model scale
Southampton water NPL 5b, S/L0.2, Fn0.65
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Ship motions
Heave measurements
5S, S/L0.2, oblique seas
5S, S/L0.4, oblique seas
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Ship motions theoretical analysis

• Development of numerical methods
• Detailed validation of numerical methods
• What are the choices?
• 2D strip theory
• 3D Greens function (or panel methods)
• 3D time domain
• 3D Rankine panel
• Linear or (partly) non-linear
• CFD

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Ship motions numerical methods

• At Southampton
• 2D strip theory - linear
• 3D Greens function
• Zero speed
• Forward speed
• 3D time domain
• Linear (under development)
• Partly non-linear
• 3D Rankine panel
• Linear (under development)
• non-linear (under development)
• CFD under development

5S, S/L0.2, 700 panels
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Ship motions head waves
5S, S/L0.4, head seas
5S, S/L0.2, head seas
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Ship motions oblique waves
5S, S/L0.4, head seas
5S, S/L0.2, head seas
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Ship motions
Fn0.0
Fn0.2
Fn0.5
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Ship motions

• Detailed investigations into
• Numerics of Greens function 2 alternative
  formulations
• Irregular frequencies removal
• Transom stern effects

Prediction
Towing tank
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Ship motions - summary

• For multi-hull craft must account for hull-hull
  interaction
• Forward speed Greens function is promising
• Correct trends with wave heading
• but
• Numerically complex
• Pitch still over-predicted
• Fngt0.70 need alternative approaches planing
  craft

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Human Factors

• Modern small, very high-speed vessels
• Fatigue, injury, long-term pain
• Quantify effects on operator (UCC)
• Heart rate, blood chemistry, muscle fatigue,
  oxygen uptake
• Link to naval architecture attributes
• Boat design, sea-state, operating manner

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Human Factors model testing

• WAL/GKN tank up to 12 m/s
• Calm water and regular/irregular waves

Conventional RIB form at 45kts
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Human Factors Full scale testing

• Robust measurement system
• 11 channels accelerations
• Wave buoy data
• GPS track
• Heart-rate of crew

Conventional RIB form at 30kts
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Human Factors

• Assisting Team Kali
• Gas turbine propelled wave-piercing RIB
• Attempt Round Britain lt30ft record

Kali at 52kts
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Summary

• Resistance understanding of components
• Wave wash operating guidelines
• Ship motions
• Experimental and numerical techniques
• Human factors
• Experimental techniques
• Collaboration with sports science
• Design techniques and operator guidelines

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Thanks and questions?
Prof. W.G. Price Prof. P. Temarel Prof. R.A.
Shenoi Dr. S.X. Du Dr. E. Ballard Dr. T.
Ahmed Dr. P. Bailey Dr. S. Georgoudis Dr. D.
Taunton Mr. O. Diken
Ms. R. Spink Mr. M. Yuceulug Mr. T. DArcy Mr.
P. Kingsland Mr. I. House LR UTC Ms. C.
Damecour RNLI - ATP
Team Kali