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FP7

STREAMLINE Résumé de rapport

Project ID: 233896
Financé au titre de: FP7-TRANSPORT
Pays: United Kingdom

Periodic Report Summary 2 - STREAMLINE (Strategic Research For Innovative Marine Propulsion Concepts)


Project Context and Objectives:

Increasing environmental concerns and soaring oil prices are creating a new focus on fuel efficiency for the marine industry. Combining low emissions with demands for more advanced vessels than ever before, drives the need for radically new propulsion concepts delivering a step-change in efficiency. Maritime transport continues to grow at twice the rate of global GDP, with between 80 to 90% of all goods imported and exported by Europe being transported by sea. Within the EU more than 40% of goods are carried by water. With the World Bank predicting that world trade will triple over the next 25 years, it is clear that the world fleet must be able to adapt to service this unprecedented growth, as well as tackle the environmental issues this will bring.

There has been little real change in the state-of-the-art for conventional screw propeller propulsion for many years with only a marginal rate of improvement during the last 50 years. More substantial progress has been achieved through the use of better propulsor configurations and improved integration of the propeller with the vessel hull hydrodynamics. These have achieved fuel savings of the order of 5% to 20%. STREAMLINE is the response of the marine community to these challenges.

Objectives

The first objective of STREAMLINE is to demonstrate radically new propulsion concepts delivering an increase in efficiency of at least 15% over the current state-of-the-art. The concepts will be designed for maximisation of energy conversion combined with low levels of cavitation, noise and vibration. The research will look at novel applications of large area propulsion, a biomechanical system and distributed thrust (via multiple propulsors).

As its second objective, STREAMLINE will investigate methods to fully optimise current State-Of-the-Art systems including conventional screw propeller systems, pods and waterjets. The key here is exploitation of new CFD methods to pursue improvements without dramatic vessel configuration changes.

The third objective of STREAMLINE is to develop advanced CFD tools and methods to optimise the hydrodynamic performance of the new propulsion concepts, particularly by analysis of integrated hull and propulsor.

Project Results:

Large Area Propeller

Two concepts have been optimised for the Large Area Propulsion concept; the first a conventional variant of an 8000 DWT tanker, with the propeller located aft of the transom with a rudder arrangement behind the propeller, the second variant has a pushing POD unit.

Biomechanical Systems

The focus for Period 2 was in three main areas: Financing, Operational Testing, Optimisation of the Pod. These three areas are all still in progress and will remain in progress until WS has secured its round of financing.

Distributed Propulsion

The major task for this reporting period was to develop and validate suitable aftship designs for hosting multiple propulsors while at the same time demonstrate inception allowance against air suction and ventilated propellers, respectively. The measured improvements of 22% resistance could not be exploited in terms of an equivalent reduction of the propulsive power. As final development loop the survey of better performing rudder propellers to achieve more exploitable resistance and thrust reduction is envisaged.

Advanced Screw Propeller Systems

CFD-based design and numerical optimisation studies have been applied to explore propulsive efficiency improvements derived by hull aftbody optimization, propeller optimisation (including a ducted propeller alternative), and integrated hull aftbody/propeller design. Results have determined new configurations that are expected to provide improvements of ship hydrodynamic efficiency up to 5% of reduced power at design conditions.

High Efficiency water jet at low speed

The selected concept has been evaluated using CFD and model testing over a wide speed range. Cavitation tunnel model tests show a significant improvement in low speed. However at high speed the performance has not been as intended with a reduction in efficiency compared to the baseline. The reason for the reduced performance is being investigated to understand why the anticipated improvements have not been demonstrated.

Advanced Pods

The ICP concept was designed and tested both in a towing tank and cavitation tunnel. Tests were carried out in a depressurised towing tank with a podded ship model.

Development of Fixed-grid / Rotating–grid Coupling

Detailed analysis of CFD simulation has been conducted from simple academic cases to a realistic hull-rudder-propeller configuration. The codes have the possibility of fully simulating complex hull-propulsive systems. The use of the new CFD features over newly optimised systems has already started with ducted or podded propellers, distributed propulsion, or with large area propellers. A simplified biomechanical system was assessed to demonstrate the possible use of the new CFD achievements for radically new propulsion concepts.

Grid Adaption

The following has been achieved: successful implementation of an adaptive mesh refinement method. and several refinement criteria have been implemented, hexahedral cells can be split isotropically or anisotropically, and vertices can be readjusted to the real geometry.

Prediction of cavitating nuisance

This work shows that using CFD can identify risks of cavitation induced harmful consequences.

RANS/BEM Coupled Method

The hybrid models developed are reliable tools to predict ship propulsion factors and other aspects of propeller/hull/rudder interaction.

Design and optimisation

Techniques were developed for multi-objective optimisation of hull forms, using 3D RANS as evaluation tool of ducts using 2D RANS as evaluation tool and propellers using a BEM code as evaluation tool. The application of the techniques showed a significant improvement in the propulsion efficiency.

Potential Impact:

Large Area Propeller

From the resistance and self propulsion tests it was found that the LAP for the conventional variant of the 8000 DWT tanker showed some 13.5 % lower power consumption compared to the original design at design speed and up to 17% at full power.

The Inclined Keel Hull studies have addressed many of the operators concerns; propeller above baseline, moderate trim within capacity of existing onboard ballast systems and propeller shaft speed within range of existing engines. The results from model test verification revealed a 4.3% maximum saving in the delivered power whilst the saving was 4% at the design speed. The findings confirm the numerical predictions for power saving and hence supporting the worthiness of the IKH concept for the design applications of large commercial vessels.

Advanced Screw Propeller Systems

Results have determined new configurations that are expected to provide improvements of ship hydrodynamic efficiency up to 5% of reduced power at design conditions.

High Efficiency water jet at low speed

The selected concept has been evaluated using CFD and model testing over a wide speed range. Cavitation tunnel model tests show a significant improvement in low speed. However at high speed the performance has not been as intended with a reduction in efficiency compared to the baseline. The reason for the reduced performance is being investigated to understand why the anticipated improvements have not been demonstrated.

Advanced Pods

The ICP concept was designed and tested both in a towing tank and cavitation tunnel. Tests were carried out in a depressurised towing tank with a podded ship model.

Development of Fixed-grid / Rotating–grid Coupling

Detailed analysis of CFD simulation has been conducted from simple academic cases to a realistic hull-rudder-propeller configuration. The codes have the possibility of fully simulating complex hull-propulsive systems. A simplified biomechanical system was assessed to demonstrate the possible use of the new CFD achievements for radically new propulsion concepts.

Grid Adaption

The following has been achieved: successful implementation of an adaptive mesh refinement method. and several refinement criteria have been implemented, hexahedral cells can be split isotropically or anisotropically, and vertices can be readjusted to the real geometry.

Prediction of cavitating nuisance

This work shows that using CFD can identify risks of cavitation induced harmful consequences. Areas of design capability improvement achieved include:

Reduced vibrations transmitted to the hull structures and noise propagated to the near field, with associated benefits;

Reduced noise signatures radiated to the farfield, with benefits for marine fauna with special impact on mammals wellness;

Reduced risk of erosion, with financial benefits for reduced maintenance and more safety by preventing loss of propeller blades or rudder effectiveness.

More reliable cavitating flow models will allow the reduction of safety margins that are typically used at design level and prevent the adoption of radical design.

RANS/BEM Coupled Method

The existing BEM solver PRO-INS has been extensively investigated. The BEM model was also extended to analyse complex propulsive configurations like contra-rotating propellers, and a new cavitation model based on fast and robust algorithms has been implemented and verified against existing models.

Design and optimisation

Techniques were developed for multi-objective optimisation of hull forms. The application of the techniques showed a significant improvement in the propulsion efficiency.

Implementation of a new Conformal Free Form Deformation (CFFD) technique allowing the description of propeller blade geometry with a small set of control points was implemented. For a state of the art propeller a possible efficiency improvement of 2-4 % was demonstrated.

List of Websites:

http://www.streamline-project.eu/


Contact

Paul Robert Greaves, (Head of Research and Technology)
Tél.: +44 1332 667308
Fax: +44 1332 242424