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TMR4225 Marine Operations,
2007.01.25
• Lecture content:
– Linear submarine/AUV motion equations
– AUV hydrodynamics
– Hugin operational experience
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Linear motion equations
• Linear equations can only be used when
– The vehicle is dynamically stable for motions in horisontal and
vertical planes
– The motion is described as small perturbations around a stable
motion, either horisontally or vertically
– Small deflections of control planes (rudders)
– For axisymmetric bodies the 6DOF equations can be split in two
sets of 2 DOF equations
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Dynamic stability
• Characteristic equation for linear coupled heave - pitch
motion:
– ( A*D**3 + B*D**2 + C*D + E) θ = 0
• Dynamic stability criteria is:
– A > 0, B > 0 , BC – AE > 0 and E>0
• Found by using Routh’s method
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Dynamic stability (cont)
• For horisontal motion the equation (2.15) can be used if
roll motion is neglected
• The result is a set of two linear differential equations with
constant coefficients
• Transform these equations to a second order equation for
yaw speed
• Check if the roots of the characteristic equation have
negative real parts
• If so, the vehicle is dynamically stable for horisontal
motion
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Methods for estimating forces/moments
• Theoretical models
– Potential flow, 2D/3D models
– Lifting line/lifting surface
– Viscous flow, Navier-Stokes equations
• Experiments
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Towing tests (resistance, control forces, propulsion)
Oblique towing (lift of body alone, body and rudders)
Submerged Planar Motion Mechanism
Cavitation tunnel tests (resistance, propulsion, lift)
Free swimming
Methods for estimating forces/moments
• Empirical models
– Regression analysis based on previous experimental results using
AUV geometry as variables
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Submarine and AUV motion equations
• 6 degrees of freedom equations
• Time domain formulation
• Simplified sets of linear equations can be used for
stability investigations
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EUCLID Submarine project
•MARINTEK takes part in a four years multinational R&D
programme on testing and simulation of submarines, Euclid
NATO project “Submarine Motions in Confined Waters”.
•Study topic:
•Non-linear hydrodynamic effects due to steep waves in
shallow water and interaction with nearby boundaries.
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Testing the EUCLID submarine in waves
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Model fixed to 6 DOF force
transducer
Constant speed
Regular waves
Submarine close to the surface
Numerical study of bow plane vortex
Streamlines released at
bow plane for 10 deg bow
plane angle (Illustration:
CFDnorway)
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Streamlines released at
bow plane for -10 deg
bow plane angle
(Illustration CFDnorway)
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AUV overview
• AUV definition:
– A total autonomous vehicle which carries its own power and does
not receive control signals from an operator during a mission
• UUV definition:
– A untethered power autonomous underwater vehicle which
receives control signals from an operator
– HUGIN is an example of an UUV with an hydroacoustic link
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AUV/UUV operational goals
• Military missions
– Reconnaissance
– Mine hunting
– Mine destruction
• Offshore oil and gas related missions
– Sea bed inspection
– Pipe line inspection
• Sea space and sea bed exploration and mapping
– Mineral deposits on sea floor
– Observation and sampling
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Offshore oil and gas UUV scenario
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Ormen Lange sea bed mapping for best pipeline track
Norsk Hydro selected to use the Hugin vehicle
Hugin is a Norwegian designed and manufactured vehicle
Waterdepth up to 800 meters
Rough sea floor, peaks are 30 – 40 meter high
Height control system developed for Hugin to ensure
quality of acoustic data
Phases of an AUV/UUV mission
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Pre launch
Launching
Penetration of wave surface (splash zone)
Transit to work space
Entering work space, homing in on work task
Completing work task
Leaving work space
Transit to surface/Moving to next work space
Penetration of surface
Hook-up, lifting, securing on deck
Hugin UUV
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AUV – Theoretical models
• Potential theory
– Deeply submerged, strip theory
– VERES can be used to calculate
• Heave and sway added mass
• Pitch and yaw added moment of inertia
– VERES can not be used to calculate
• Surge added mass
• Roll added moment of inertia
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AUV- Theoretical models
• Viscous models
• Solving the Navier Stokes equations
– Small Reynolds numbers (< 1000)
: DNS
– Medium Reynolds numbers (< 10**5) : LES – Large Eddy Simulation
– High Reynolds numbers (> 10**5)
: RANS – Reynolds Average
Navier Stokes
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AUV – Theoretical models
• 3D potential theory for zero speed - WAMIT
– All added mass coefficients
– All added moment of inertia coefficients
– Linear damping coefficient due to wave generation
• Important for motion close to the free surface
• More WAMIT information
– http://www.wamit.com
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NTNU/Marine Technology available
tools:
• 2 commercial codes
– Fluent
– CFX
• In-house research tools of LES and RANS type
• More info: Contact Prof. Bjørnar Pettersen
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AUV – Experimental techniques
• Submerged resistance and propulsion tests
– Towing tank
– Cavitation tunnel
• Submerged Planar Motion Mechanism tests
– Towing tank
• Oblique towing test
– Towing tank
• Lift and drag test, body and control planes
– Cavitation tunnel
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AUV – Experimental techniques
• Free sailing tests
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Towing tank
Ocean basin
Lakes
Coastal waters
• Free oscillation tests/ascending test
– Water pool/ Diver training pool
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HUGIN history
• AUV demo (1992-3)
– Diameter:
– Displacement:
0.766 m
1.00 m**3
Length: 3.62/4.29 m
• HUGIN I & II (1995-6)
– Diameter:
– Displacement:
0.80 m
Length: 4.8 m
1.25 m**3
• HUGIN 3000C&C and 3000CG (1999-2003)
– Diameter:
– Displacement:
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1.00 m
Length: 5.3 m
2.43 m**3
NTNU/MARINTEK HUGIN
involvement
• AUV demo (1992-3)
– Model test in cavitation tunnel, open and closed model, 2 tail
sections (w/wo control planes)
• Resistance, U = {3,10} m/s
• Linear damping coefficients for sway, yaw, heave and pitch, yaw/trim
angles {-10, 10} degrees
– 3D potential flow calculation
• Added mass added moment of intertia
– Changes in damping and control forces due to modification of
rudders
– Student project thesis
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NTNU/MARINTEK HUGIN
involvement
• HUGIN 3000
– Resistance tests, w/wo sensors
• Model scale 1:4
• Max model speed 11.5 m/s
• Equivalent full scale speed?
– Findings
• Smooth model had a slightly reduced drag coefficient for increasing
Reynolds number
• Model with sensors had a slightly increased drag coefficient for
increasing Reynolds numbers
• Sensor model had some 30% increased resistance
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HUGIN information
• New vessels have been ordered late 2004 and 2005
– One delivery will be qualified for working to 4500 m waterdepth
• New instrumentation is being developed for use as a tool
for measuring biomass in the water column
• Minecounter version HUGIN 1000 has been tested by
Royal Norwegian Navy
• More Hugin information: see Kongsberg homepage for
link
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HUGIN field experience
• Offshore qualification seatrials (1997)
• Åsgard Gas Transport Pipeline route survey (1997)
• Pipeline pre-engineering survey (subsea condensate
pipeline between shorebased process plants at Sture and
Mongstad) (1998)
• Environmental monitoring – coral reef survey (1998)
• Fishery research – reducing noise level from survey tools
(1999)
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HUGIN field experience
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Mine countermeasures research (1998-9)
Ormen Lange pipeline route survey (2000)
Gulf of Mexico, deepwater pipeline route survey (2001 ->)
Raven, West Nile Delta, Egypt, area of 1000 km**2 was
surveyed late 2005 by Fugro Survey
– Sites for subsea facilities
– Route selection for flowlines, pipelines & umbilicals
– Detect and delineate all geo-hazards that may have an impact on
facilities installetion or well drilling
– Survey area water depth: 16 – 1089 m (AUV used for H > 75 m)
– Line spacing of 150 m and orthogonal tie-lines at 1000 m intervals
– Line kilometers surveyed by AUV: 6750 km
– Distance to seabed (Flying height): 30-35 m
– Operational speed: 3.6 knots
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Fugro survey pictures
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http://www.fugrosurvey.co.uk/
Actual HUGIN problems
• Inspection and intervention tasks
– Adding thrusters to increase low speed manoeuvrability for
sinspection and intervention tasks
• Types, positions, control algorithms
– Stabilizing the vehicle orientation by use of spinning wheels
(gyros)
• Reduce the need for thrusters and power consumption for these types
of tasks
– Docking on a subsea installation
• Guideposts
• Active docking devices on subsea structure (robotic arm as on space
shuttle for capture of satelittes)
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Actual HUGIN problems
• Roll stabilization of HUGIN 1000
– Low metacentric height
– 4 independent rudders
– PI type regulator with low gain, decoupled from other regulators
(heave – pitch – depth, sway – yaw, surge)
– Task: Keep roll angle small ( -> 0) by active control of the four
independent rudders
• Reduce the need for thrusters and power consumption for these types
of tasks
– Docking on a subsea installation
• Guideposts
• Active docking devices on subsea structure (robotic arm as on space
shuttle for capture of satelittes)
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Future system design requirements
• Launching/ pick-up operations up to Hs = 5 m when ship is
advancing at 3-4 knots in head seas
• Increasing water depth capability
• Increased power capability
– Operational speed 3- 4.5 knots
– Mission length 3- 4 days
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Hugin deployment video
• Video can be downloaded from Kongsberg
homepage
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