thrusters thrust degradation in dp operationsdynamic- .thrusters thrust degradation in dp ... o...

Download Thrusters Thrust Degradation in DP Operationsdynamic- .Thrusters Thrust Degradation in DP ... o Thrust

Post on 31-Aug-2018

215 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Thrusters

    Thrust Degradation in DP OperationsDP Model Test of an Aframaz Shuttle Tanker Methods

    Results, Operations

    Reinert Nordtveit - Teekay Corporation

    Bjrn Nygrd - Kongsberg Maritime AS

    Egil Jullumstr - MARINTEK

    October 9-10, 2007Return to Session DirectoryReturn to Session Directory

  • T E E K A Y T H E M A R I N E M I D S T R E A M C O M P A N Y

    www.teekay.com

    Dynamic Positioning Conference Houston, 2007

    Thrust Degradationin DP Operations

    DP Model Test of an Aframax Shuttle Tanker

    by

    Reinert Nordtveit Teekay CorporationBjrn Nygrd Kongsberg Maritime

    Egil Jullumstr - Marintek

    Return to Session DirectoryReturn to Session Directory

  • 2 www.teekay.com

    DP model test of an IMO Class 2 Shuttle Tanker

    Focus ono Thrust degradation effectso Environmental design criteriao DP performance and design evaluation

    R&D project with the partners:Teekay, Kongsberg Maritime and Marintek

    Introduction

    Return to Session DirectoryReturn to Session Directory

  • 3 www.teekay.com

    Transports more than 10 percent of the worlds seaborne oil Operates more than 190 vessels / 41 DP shuttle tankers Global organization / 17 countries / 6,300 employees More than 19.000 cargo lifts carried out by shuttle tankers during the

    past 25 years Offshore loading using DP control is a safe and reliable operation Continuous focus to improve design and operational excellence

    Teekay Corporation

    Return to Session DirectoryReturn to Session Directory

  • 4 www.teekay.com

    Project Incentive

    Experience from operations in harsh weather conditions have shown indications of lower margins on the vessels station keeping performance than calculated by theoretical analyses such as DP capability plots

    A lack of industrial practices on how thrust degradation effects and environmental design criteria are defined and incorporated in DPcapability analyses in general has been identified

    The main drivers are to further improve the safety, efficiency and regularity of offshore loading operations

    Return to Session DirectoryReturn to Session Directory

  • 5 www.teekay.com

    Dynamic Positioning - Force Balance Exercise

    Propeller forces counteract drifting forces

    Propeller forces delivered by

    Main propellers and high lift ruddersTunnel and azimuth thrusters

    Return to Session DirectoryReturn to Session Directory

  • 6 www.teekay.com

    Dynamic Positioning - Force Balance Exercise

    Propeller forces counteract drifting forces

    Drifting forces determined by

    Environmental conditionsVessels main particulars

    Return to Session DirectoryReturn to Session Directory

  • 7 www.teekay.com

    Environmental Design Criteria

    Environmental design criteria for offshore loadingCorresponding to Halten area Norwegian Sea

    1.81.8Peak enhancement factor []

    JONSWAPJONSWAPWave spectrum

    12 Seconds11 SecondsWave spectrum peak period [Tp]

    1knot1 knotCurrent speed [Cv]

    38 knots31knotsWind speed [U10]

    5.5 m4.5 mSignificant wave height [Hs]

    DisconnectionConnection

    Return to Session DirectoryReturn to Session Directory

  • 8 www.teekay.com

    Thrust and Propeller Forces

    Nominal thrust Thrust degradation = Thrust available

    Thrust degradation

    Thrust degradation affected by

    o thruster-hull interactions (Coanda)o thruster-thruster interactionso sea current o wave effectso ship motionso thruster ventilation

    nomTT

    =

    Return to Session DirectoryReturn to Session Directory

  • 9 www.teekay.com

    Model and Thruster Configuration

    Two aft ships; single and twin screw

    Interchangeable forebody

    Model scale 1:25, L 10 m , Displ. 6.9 mt

    Return to Session DirectoryReturn to Session Directory

  • 10 www.teekay.com

    Model and Thruster Configuration

    Return to Session DirectoryReturn to Session Directory

  • 11 www.teekay.com

    Thrust Loss Model Test

    Measurement of thrust degradation forMain propellers and rudders - single and twin screwTunnel thrusters - fwd and aftAzimuth thrusters fwd and aft

    Loading conditionsBallastLoaded

    Environmental ConditionsCalm waterOffshore loading criteria; connection and disconnectionCorresponding to Halten Area in the Norwegian Sea

    Return to Session DirectoryReturn to Session Directory

  • 12 www.teekay.com

    Thrust Loss Model Test

    Thrust degradation measurement program comprised the following

    Open water characteristics for all propeller and thruster units

    Thruster thruster interactions

    Thruster hull interactions

    Thruster rudder interactions

    Tunnel thruster losses

    Thrust degradation due to current

    Thrust degradation due to waves

    Thrust degradation due to ventilation

    Return to Session DirectoryReturn to Session Directory

  • 13 www.teekay.com

    Thrust Loss Model Test - Results

    Thrust reduction coefficients - bow azimuth thruster

    0.00

    0.25

    0.50

    0.75

    1.00

    0 60 120 180

    Thrust angle [deg]

    [-]

    Ballast condition

    Loaded condition

    Thrust degradation measurements for bow azimuth thruster

    Return to Session DirectoryReturn to Session Directory

  • 14 www.teekay.com

    Thrust Loss Model Test - ResultsThrust degradation measurement for aft azimuth thruster

    Thrust reduction coefficients - aft azimuth thruster

    0.00

    0.25

    0.50

    0.75

    1.00

    0.0 60.0 120.0 180.0

    Thrust angle [deg]

    [-]

    Ballast condition

    Loaded condition

    Return to Session DirectoryReturn to Session Directory

  • 15 www.teekay.com

    Thrust Loss Model Test - Results

    Thrust degradation measurement for main propeller and tunnel thrusters

    0.800.65Tunnel thruster - aft

    0.800.65Tunnel thruster bow

    0.870.75Main propeller twin-screw

    0.850.75Main propellersingle-screw

    Loaded conditionBallast condition

    Thrust degradation coefficients Main propeller and tunnel thrusters

    Return to Session DirectoryReturn to Session Directory

  • 16 www.teekay.com

    DP Model Test

    Marintek Ocean Basin, 80m x 50m x 10mOff-the-shelf DP softwareNorth Sea environmental conditionsBallast and loaded conditionsIntact and failure modeVarious power settings for thrustersTest duration; 1 hour full scale time / 12 minutes model scale time

    Return to Session DirectoryReturn to Session Directory

  • 17 www.teekay.com

    DP Model Test

    Return to Session DirectoryReturn to Session Directory

  • 18 www.teekay.com

    DP Model Test - Results

    0 500 1000 1500 2000 2500 3000 350040

    60

    80

    Time (s)

    Radial distance to buoy (m)

    1hour DP in FAILURE MODE

    MARINTEK, 18:00 26-Sep-2007

    T:\Prosjekt\P53 Marine Vehicles\530346 Teekay Aframax IMO DP2 Shuttle Tanker\Matlab\plot_TOT_dist_530233

    Run # 620 :: LOADED HS5.5 TP12 UC1 UW38Run # 320 :: BALLAST IRR H5.5 TP12 UC1 UW38

    Return to Session DirectoryReturn to Session Directory

  • 19 www.teekay.com

    DP Capability PlotStatic force balanceAuto position mode is assumedTandem offshore loading is a weather vane operationSector around the bow of relevance for shuttle tankers Thrust degradation calculation included in StatCap

    Thrust reduction coefficients - bow azimuth thruster

    0.00

    0.25

    0.50

    0.75

    1.00

    0.0 60.0 120.0 180.0

    Thrust angle [deg]

    [-]

    CalculationsMeasurementsBarred azimuth sectorAverage (from measurements)

    Return to Session DirectoryReturn to Session Directory

  • 20 www.teekay.com

    DP Capability Plot - ExampleWorst case single failure for a DP2 single screw shuttle tankerNorth sea environmental design conditions - ballast

    Plot 1: Thrust degradation not included Plot 2: Thrust degradation included

    Return to Session DirectoryReturn to Session Directory

  • 21 www.teekay.com

    Conclusions

    Thrust degradation effects are of significant importance for all types of DP vessels

    Thrust degradation effects should be accounted for in design andoperation of DP vessels

    Magnitude depends on vessel design, operation and environmental conditions

    Thrust degradation calculations have been included in software for DP capability analysis; KM StatCap

    Calculations correspond reasonably well with model test measurements for a shuttle tanker

    Results from DP capability analysis (capability plot) correspondwell with shuttle tanker operational experience

    Return to Session DirectoryReturn to Session Directory

  • 22 www.teekay.com

    Questions ?Questions ?Thank you!Thank you!

    Dynamic Positioning Conference Houston, 2007

    Return to Session DirectoryReturn to Session Directory

Recommended

View more >