CFD Developments and R&D Projects at STX...

© HER MAJESTY THE QUEEN IN RIGHT OF CANADA (2009)

Dan VyselaarProject Naval Architect, STX Canada MarineSeptember 1st, 2009

CFD Developments and R&D Projects at STX Marine

15-Oct-09 |

Presentation Overview

Company Overview

Current CFD development work at STX Canada & US Marine

AOPS Project Introduction

AOPS Hull Form Optimization

AOPS Heli-deck Turbulence Analysis

15/10/2009 |

Company Overview - STX Marine Inc.

STX Canada Marine Inc. and STX US Marine Inc. are wholly owned subsidiaries of STX Europe ASA with offices located in:

Vancouver, British Columbia, - Main technical office, 35 - 40 staff depending upon project load

Houston, Texas, - 8 staff supplemented by others from Vancouver or contractors as required

15/10/2009 |

One of the world's largest shipbuilders

Comprises 18 yards in 8 countries

20 000 employees

Now part of STX Corp

12 3

4

9

119 10

1213

1. Aker Yards, Brattvaag

3. Aker Yards, Langsten

5. Aker Yards, Tulcea

7. Aker Yards, Brevik

2. Aker Yards, Søviknes

4. Aker Yards, Aukra

6. Aker Yards, Brazil

8. Aker Yards, Braila

10. Aker Yards, Helsinki 14. Aker Yards, Wismar

12. Aker Yards, Lorient11. Aker Yards, Rauma

15. Aker Yards, Warnemûnde

13. Aker Yards, Saint Nazaire

16. Damen Shipyards Okean*

6

17. Aker Yards, Florø

9. Aker Yards, Turku

123

4

7

8 5

14

16

17

15

* Joint venture** Under construction

18. Aker Yards, Vung Tau**

Company Overview - STX Europe

15/10/2009 |

Company Overview - STX Marine Company History

STX Canada Marine Inc. - Vancouver

STX US Marine Inc. – Houston

Changed name to Wartsila Marine Inc.

1983

Relocated US operationto Houston TX

Changed name to Aker Marine Inc.

1991 2004

Wartsila Arctic Office open in

Vancouver

Name change to Kvaerner Masa Marine

1993

Opened US office in Annapolis, MD

Acquired Polar Design AssociatesFormerly Cleaver & Walkingshaw

1987 2006

Name change to Aker Yards Marine Inc.

1998 2008

Name change to STX Canada and US Marine Inc.

15/10/2009 |

STX Canada / US Marine, StrengthsStrong Links to Technology Groups in STX Europe Group

o STX Europe ASA Projects (Offshore Support Vessels) o Aker Arctic Technology Oy (Ice Technology)

Principal Business is Design of Ships and Marine StructuresStrong Analytical Skill Base

o Naval Architecture, o Structural Design, o Marine Engineering, o Advanced Analysis (FEA, CFD, Motions, DP, Mooring).

Total of 15 vessels to STX Marine Marine design currently under construction or on order, 9 for Offshore Service

Design Capability Ranging from Concept to Production – “Cradle to Grave” Solutions

15-Oct-09 |

Current CFD Developments - CFD Usage at STX Marine

Have used Comet, Star CD and Star CCM+ for the past 8 years,

Currently license StarCCM+

Five staff with CFD experience, and fluid mechanics expertise (primarily in experimental external aero and hydro dynamics, ie. Wind tunnels, tow tanks and ocean basins)

15-Oct-09 |

Current CFD Developments - STX Fluid Mechanics Expertise CFD is used in many aspects of design work:

• Naval Architecture / Hull form design– Resistance and powering calculations– Appendage alignment– Bulbous bow shape– Propeller / wake inflow (not including propeller analysis yet)– Seakeeping / hull damping

• Marine Engineering– Ventilation / heat transfer to machinery spaces or ro/ro ferry

decks– LNG cooldown, sloshing analysis– Exhaust particle tracking / combustion / fire

• CFD Consultancy for non marine jobs:– Industrial furnace combustion– Earthquake induced pressures– LNG tank cooldown, sloshing, etc

Typical Non Marine CFD jobs:

15-Oct-09 |

Current CFD Developments – Current R&D

Main focus areas of current R&D:

Powering predictions with Star CCM+• For several years we have been conducting hull

optimization studies using RANS methods• Next step is complete powering predictions• Uncertainty in scale up procedures still needs to be

resolved

Seakeeping predictions with Star CCM+• Using RANS codes with potential flow codes to accurately

predict hull damping works quite well• Accuracy of complete time domain simulations currently

under R&D

Powering Predictions – Traditional Scale Up From Tow Tank Results To date, most models run at STX Marine have been model scale. Reason for this is tow tank model testing matches Froude numbers

(wave drag) but not Reynold’s numbers (viscous drag). This disconnect allows much smaller meshes to be used

Tow tank methods are well validated and have been in use for more than 140 years

( )

AModelR

FullScaleV

FullScaleTotal

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Current CFD Developments – Powering Predictions

Powering predictions to date involve carefully calibrated work against existing model tests, or comparative models between hull variants. Accuracy levels are typically ~ 5%, with frictional resistance very accurately predicted.

Wave and pressure drag remains more difficult to accurately determine, fluctuations are seen, convergence is difficult, and determination of a form factor for powering procedures remains uncertain as the best way forward

Some hulls have worked very well with a modified double body approach to calculate the form factor; for other (primarily bluff hulls) this approach overestimates the form factor substantially

Part of the problem lies in the model test approach itself – the form factor is not actually independent of Reynold’s number

Current CFD Developments – Powering Predictions

Typical Convergence of Pressure Drag

0

10

20

30

40

50

60

0 500 1000 1500 2000 2500

Iteration

Pres

sure

Dra

g [N

]

Pressure Drag

Current CFD Developments – Typical Powering Predictions

MS Veendam Ducktail Design

Current CFD Developments – Typical Powering PredictionsMS Veendam Ducktail Design

Current CFD Developments – Seakeeping Predictions

For some time now RANS methods have been used to predict hull damping forces, greatly improving accuracy of potential flow codes

Validation of time domain simulations is the next step; while computationally very expensive, external verification of extreme motions / non linear responses, and quicker turn around times than model basins are key drivers

While models have not been run for sufficient duration to generate statistics for comparison to model basin results, preliminary results are qualitatively very promising

Current CFD Developments – Seakeeping Predictions

Current CFD Developments – Seakeeping Predictions 3 m seas

Roll Angle

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-1

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0 2 4 6 8 10 12 14 16

Time (s)

Angl

e (d

eg)

Measured Roll Angle - Tow Tank Experiments

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0.50

125.00 130.00 135.00 140.00 145.00 150.00 155.00

Time [s]

Ro

ll A

ng

le [

deg

]

Current CFD Developments – Seakeeping Predictions 3 m seas

Heave

-3

-2

-1

0

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0 2 4 6 8 10 12 14 16

time (s)

Heav

e (m

)

Measured Heave Motion - Tow Tank Experiments

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

145.00 150.00 155.00 160.00 165.00 170.00 175.00

Time [s]

Hea

ve [m

]

15/10/2009 |

AOPS Project Overview - Primary Ship Requirements

Requirements: Designed to Class Society and Commercial Ship Standards Break up to 1m of Level Ice (IACS Polar Class 5) Open Water Speed of 17 knots Good Seakeeping for Offshore Patrol Missions


15/10/2009 |

AOPS Principal Particulars

LOA 97.5 mLWL 87.0 mBOA 19.0 mT 5.7 mDisplacement 5730 tonnesPropulsion Power 2 x 4500 kW

To meet these requirements, hull needs to be designed to have a strong balance of capabilities between:Icebreaking, Seakeeping, Manoeuvrability, and Powering performance


15/10/2009 |

Hull Form Optimization using Computational Fluid Dynamics

Since a new hull has been required for this vessel, extensive development work has been done for the hull, with our ice breaking experts at STX Canada and Aker Arctic, and our hydrodynamics department at STX Canada to meet the high speed and ice breaking requirements for the vessel

CFD modelling has been used to evaluate the drag of differing appendages, hull shapes and construction methods


15/10/2009 |




Powering Predictions - CFD vs Model Tests

0 2 4 6 8 10 12 14 16 18

Speed [knots]

CFD Results Model Test Results


15/10/2009 |

Superstructure Optimization Using CFD

The AOPS is equipped with aviation facilities to support a variety of different military and civilian helicopters.

CFD modeling has been used to investigate the turbulence levels and vertical velocities over the flight deck in differing wind conditions.

All modeling done at full scale, unsteady simulations, monitoring standard deviations of vertical velocity


AOPS Helideck Turbulence Calculation – Head wind


Wind from 15 deg off bow streamlines


Velocity contour at 19m elevation (rotor plane) for wind at 15 deg off bow


15/10/2009 |

Conclusion

•Powering calculations to date have been very promising, with several ships now delivered that have had powering calculations either done in combination with model tests, or starting from a known performance point.

•Current R&D efforts at STX Marine are focused on developing in house procedures for powering calculations, and best practices for form factor approaches, to allow complete powering calculations to be done for a new hull. Very promising results have been seen on recent projects, including tankers (not presented), and AOPS

•Additional R&D efforts will be spent in the future on validation of time domain seakeeping calculations.

•CFD has played a key role in the preliminary hull design stage of many recent vessels. For the AOPS project much of the preliminary appendage and hull design was done using CFD

Questions?


CFD Developments and R&D Projects at STX...

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