wartsila sp ppt 2011 arctic

Considerations for Propulsor Selection For Operation in Ice

Part 2 The Propulsion Concept of the European Research Icebreaker

“AURORA BOREALIS”

Arctic Shipping Summit 2011 HELSINKI, 12th to 14th of April, 2011

Willy Doelling Wärtsilä Ship Design Germany

1 © Wärtsilä August 12, 2010 European Research Icebreaker AURORA BOREALIS

The Project

• AURORA BOREALIS is the combination of three different ship types in one:

• A Heavy Icebreaker

• A Multifunctional Research Vessel

• A Scientific Drill Ship

The Background of the Project

• Following the rapid changes in global climate, the German Science Council recommended the construction of AURORA BOREALIS.

• The German Ministry for Education and Research funded the initial design and planning of AURORA BOREALIS.

• The Alfred Wegener Institute for Polar and Marine Research awarded Wärtsilä Ship Design Germany with the contract to create and validate the design.

• An international group of institutions and agencies, united in the European Research Icebreaker Consortium (ERICON) and funded by the European Union, currently plans construction and operation of AURORA BOREALIS.

• Provided the securing of funding in time, AURORA BOREALIS is scheduled to be completed in 2015.

The Vessel’s Missions

AURORA BOREALIS has to fulfill three distinct and highly challenging missions:

• Autonomously navigate in the ice-covered waters of the Arctic and Antarctic, throughout the year.

• Facilitate scientific research in polar and nonpolar regions in the fields of oceanography, geology, biology, glaciology, meteorology, geophysics, atmosphere physics and bathymetry, throughout the year.

• Autonomously perform scientific drilling operations in polar and non-polar regions, throughout the year, without any assistance from outside.

Specification

Length over all 199.85 m Cruising speed 15.5 kt Length between perpendiculars 174.27 m Persons on Board 120 Maximum moulded breadth 49.00 m Ice Class PC1 Depth to working deck 17.75 m Installed Power 94 MW Draught max 13.25m Independent moon pools 2 pcs

Vessel functionality from -50°C and research work from -30°C to +45°C.

Cross Section i.w.o. fwd Moonpool/Atrium

Special designed cross section:

• Inclined bottom to avoid ice sticking to the shell

• Improved ice breaking capability in manoeuvring and station keeping by means of side balcony in conjunction with controlled roll and pitch motions

• Wave reflection in open waters by side balcony

• Accommodation of centre line moon pools and related atrium with laboratories and skylight.

Subdivision and Power Plant Arrangement

Safety, reliability and redundancy have been given the highest possible attention:

• Double- and triple-hull arrangements.

• 8 gensets of total 94 MW in 2 separate compartments.

• Fully separated engine and switchboard rooms.

Main Propulsion Requirements

• Transit over extensive distances (e.g. from Arctic to Antarctic) at a service speed of 15.5 knots/18,000kW propulsion power.

• Continuous ice breaking of 2.5m multi year ice of 700 kPa at 3 knots as well ahead as astern.

• Breaking through ice ridges of up to 15. meters.

• IACS Ice Class PC1 (and above where necessary).

• Robust and simple design. • Well-proven and reliable technology. • Maintenance and repairs by means of

onboard facilities. • Access to all components and systems while

the vessel is afloat (as far as feasible). • Low-noise requirements for research work.

Main Propulsion Arrangement

• Triple, ice-reinforced fixed pitch propellers of 6.50 m diameter and with 27 MW each, powered by a 94 MW diesel-electric plant with one single centre line rudder.

• Minimum 4m tip clearance of the propeller to the shell to allow for undisturbed ice flow above the propellers.

• No appendages to obstruct the ice flow along the shell, especially when going astern.

• Propulsion and manoeuvering devices, as well as deep-sea multi-beam echo-sounders, to be free of ice during navigation ahead and astern.

• Most possible circular homogenous wake field in way of the propellers for minimized vibrations and best efficiency.

• Moderate specific load of the propellers in full power condition to avoid noise and cavitation.

• Good course- and sea keeping capabilities in open water.

• Avoidance of big masses at the extreme ends of the vessel for reasons of longitudinal moment of inertia.

Good luck for the propulsion:

The operational icebreaking draught of 13.25 m allows for a significant

submersion of the propellers, thus virtually no propeller/ice interaction:

• Tip of propeller blade below water surface 6.50 m

• Minimum clearance of propeller tip to shell 4.00 m

• Main Propeller: 3 x 6.50 m Diameter / fixed pitch / 5-bladed

P/D 1.060

Ae/Ao 90 %

Pd/Ao (full load icebreaking) 800 kW/m²

N (15.5 knots) 80 / min

• Bollard Pull 680 t

• Transit Speed 15.5 knots 17,000 kW

• Maximum Speed (blocked) 20.0 knots 50,000 kW

• Inclination of side shaft lines to the centre line to prevent from ice blocking when going astern.

• Clearance between propeller and shell to allow for unobstructed ice flow.

• Electrical drives via gearboxes for weight and space reasons.

• Contours of ice-knifes edges indicated by white lines

• Flat buttocks for proper ice flow above the propellers

Station Keeping

• AURORA BOREALIS is also designed to autonomously keep station as well in open water as in drifting level ice.

• Therefore, she is also equipped with six retractable nozzled transverse thrusters of 4.5 MW each.

• In order to conduct controlled ice breaking in DP-mode at very reduced speed, her main propeller and the six transverse thrusters push the ship against the ice until being closest to breaking it. Then a unique active ballast system gives the ship a pitching and rolling motion and in combination with her special hull form, the ice will be broken just in such a way that the breaking speed corresponds to the ice drifting speed. Thus the vessel can operate in DP-mode in drifting level ice keeping its position.

Model Tests

And the concept has of course been extensively tested at Aker Arctic…

... and the Hamburg Ship Model Basin, at a total of 27 days in the ice tanks…

Model Tests

Motion Management during Station Keeping

Controlled Icebreaking through Induced Harmonic Roll and Pitch Motions at very reduced relative speed

Conclusions

• AURORA BOREALIS features a propulsion system which is governed by the following:

• The special and individual tasks of the vessel and the thereof resulting displacement at a restricted length call for a significant draught and beam.

• This draught and beam, appreciating the propulsion power requirements for ice breaking, and the provision of a 4m clearance between propeller tip and hull to avoid propeller/ice interaction, lead to a triple screw arrangement.

• The triple screw arrangement allows for an acceptable propeller load, high flexibility and manoeuverability as well as to an increased redundancy in propulsion.

Wärtsilä Ship Design Germany GmbH Bernhard-Nocht-Straße 113 20359 Hamburg Germany

Phone: +49 40 37 60 90 Fax: +49 40 37 33 15

E-mail: shipdesign.germany@wartsila.com Internet: www.wartsila.com/shipdesign

Thank you for your attention!

wartsila sp ppt 2011 arctic

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