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TMR 4225 Marine Operations, 2007. 01. 25 • Lecture content: – Linear submarine/AUV motion TMR 4225 Marine Operations, 2007. 01. 25 • Lecture content: – Linear submarine/AUV motion equations – AUV hydrodynamics – Hugin operational experience 1

Linear motion equations • Linear equations can only be used when – The vehicle 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 6 DOF equations can be split in two sets of 2 DOF equations 2

Dynamic stability • Characteristic equation for linear coupled heave - pitch motion: – ( 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 3

Dynamic stability (cont) • For horisontal motion the equation (2. 15) can be used 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 4

Methods for estimating forces/moments • Theoretical models – Potential flow, 2 D/3 D models Methods for estimating forces/moments • Theoretical models – Potential flow, 2 D/3 D models – Lifting line/lifting surface – Viscous flow, Navier-Stokes equations • Experiments – – – 5 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 Methods for estimating forces/moments • Empirical models – Regression analysis based on previous experimental results using AUV geometry as variables 6

Submarine and AUV motion equations • 6 degrees of freedom equations • Time domain Submarine and AUV motion equations • 6 degrees of freedom equations • Time domain formulation • Simplified sets of linear equations can be used for stability investigations 7

EUCLID Submarine project • MARINTEK takes part in a four years multinational R&D programme 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. 8

Testing the EUCLID submarine in waves • • 9 Model fixed to 6 DOF Testing the EUCLID submarine in waves • • 9 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 Numerical study of bow plane vortex Streamlines released at bow plane for 10 deg bow plane angle (Illustration: CFDnorway) 10 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 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 12

AUV/UUV operational goals • Military missions – Reconnaissance – Mine hunting – Mine destruction 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 13

Offshore oil and gas UUV scenario • • • 14 Ormen Lange sea bed Offshore oil and gas UUV scenario • • • 14 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 • • • 15 Pre launch Launching Penetration of Phases of an AUV/UUV mission • • • 15 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 16 Hugin UUV 16

AUV – Theoretical models • Potential theory – Deeply submerged, strip theory – VERES 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 17

AUV- Theoretical models • Viscous models • Solving the Navier Stokes equations – Small 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 18

AUV – Theoretical models • 3 D potential theory for zero speed - WAMIT AUV – Theoretical models • 3 D 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 19

NTNU/Marine Technology available tools: • 2 commercial codes – Fluent – CFX • In-house 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 20

AUV – Experimental techniques • Submerged resistance and propulsion tests – Towing tank – 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 21

AUV – Experimental techniques • Free sailing tests – – Towing tank Ocean basin AUV – Experimental techniques • Free sailing tests – – Towing tank Ocean basin Lakes Coastal waters • Free oscillation tests/ascending test – Water pool/ Diver training pool 22

HUGIN history • AUV demo (1992 -3) – Diameter: – Displacement: 0. 766 m 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 3000 C&C and 3000 CG (1999 -2003) – Diameter: – Displacement: 23 1. 00 m Length: 5. 3 m 2. 43 m**3

NTNU/MARINTEK HUGIN involvement • AUV demo (1992 -3) – Model test in cavitation tunnel, 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 – 3 D potential flow calculation • Added mass added moment of intertia – Changes in damping and control forces due to modification of rudders – Student project thesis 24

NTNU/MARINTEK HUGIN involvement • HUGIN 3000 – Resistance tests, w/wo sensors • Model scale 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 25

HUGIN information • New vessels have been ordered late 2004 and 2005 – One 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 26

HUGIN field experience • Offshore qualification seatrials (1997) • Åsgard Gas Transport Pipeline route 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) 27

HUGIN field experience • • Mine countermeasures research (1998 -9) Ormen Lange pipeline route HUGIN field experience • • 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 28

Fugro survey pictures 29 http: //www. fugrosurvey. co. uk/ Fugro survey pictures 29 http: //www. fugrosurvey. co. uk/

Actual HUGIN problems • Inspection and intervention tasks – Adding thrusters to increase low 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) 30

Actual HUGIN problems • Roll stabilization of HUGIN 1000 – Low metacentric height – 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) 31

Future system design requirements • Launching/ pick-up operations up to Hs = 5 m 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 32

Hugin deployment video • Video can be downloaded from Kongsberg homepage 33 Hugin deployment video • Video can be downloaded from Kongsberg homepage 33