Challenging wind and waves Linking hydrodynamic research to the maritime industry

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1 Challenging wind and waves Linking hydrodynamic research to the maritime industry

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3 Meeting the Industry s Needs MARIN has been expanding the boundaries of maritime understanding with hydrodynamic research for over 80 years. Today, this research is applied for the benefit of Concept Development, Design Support, Operations Support and Tool Development. The services incorporate a unique combination of simulation, model testing, full-scale measurements and training programmes. Pro-active response to market needs By feeding back the results of advanced research programmes into commercial projects, MARIN has created a powerful synergy with the maritime industry. This industry is being confronted with shorter cycle times and increasing global competition in challenging environmental and economic conditions. By becoming involved in projects as early as possible, MARIN can help meet these challenges. Our customers include commercial ship builders, fleet owners, navies, naval architects and offshore companies the world over. A dual mission We have a dual mission: to provide industry with innovative design solutions and to carry out advanced research for the benefit of the maritime sector as a whole. In this way, we strengthen the link between academic research and market needs. It is a unique interaction that benefits all parties concerned. The driving force behind this dual mission is a team of highly motivated and experienced people. MARIN is innovative, independent and above all, reliable. Reliable, independent and innovative MARIN, the Maritime Research Institute Netherlands, has become a reliable, independent and innovative service provider for the maritime sector and a contributor to the well being of society. We take initiative to couple our own expertise to various application areas to broaden our ability to solve problems. By maintaining our leadership position in hydrodynamic and nautical research and development, we make our accumulated know-how and experience available for Concept Development, Design Support, Operations Support and Tool Development. This commitment to high-quality technological innovation enables you to meet the challenges facing your industry today. 3

4 Extending Boundaries We extend boundaries by supporting the entire design process from validating initial ideas to measuring the performance of finished products. The shipyard, designer or architect retains overall responsibility for a project, while MARIN provides complementary skills and expertise where required. Regardless of the degree of support, customers gain access to the Concept Development - exploring possibilities Concept Development involves taking a ship, offshore construction or a harbour project from its concept specifi cations to a design ready to be taken to the next level. Together with naval architects and designers, we evaluate the specifications, identify limitations, make recommendations for improvement, and then provisionally verify the key para meters using computer simulation and elementary testing techniques. We look at propulsion performance, motion optimisation, structural response, manoeuvrability and safety, and draw on experience gained in operational performance research programmes. Operations Support - improving performance Once built, a ship or offshore construction may benefit from MARIN s expertise through Operations Support. From crew training using state-of-the-art simulators to on-board measurements, the design is optimised in service. Operations Support ensures the ship does what it is designed for with the utmost safety, efficiency and cost-effectiveness. If it fails to meet expectations, we carry out full-scale investigations and analysis. Results from model tests and computer simulations obtained from Design Support are cross-referenced with actual measurements. This process helps MARIN to validate its modelling techniques to ensure they represent full-scale performance. 4 extensive know-how, experience and facilities available within MARIN. Design Support - interacting to achieve perfection Starting with a validated specification, Design Support helps arrive at a solution. Because of time and commercial pressures in the development of ship or offshore constructions, we interact closely with the customer s design team, and assure swift simulation and modelling. The design is refined using state-of-the-art facilities and tools. We consider life-time performance parameters like speed, manoeuvrability, motions and loads as well as safety and legal requirements. By simulating performance, considerable savings can be made in future operational and maintenance costs. Tool Development - making know-how accessible Developing software and hardware tools for use in the design and operational verification of ships, offshore constructions and harbours is an area in which MARIN draws heavily on its knowledge resources from both research and commercial projects. Projects range from tools for calculating specific performance parameters to custom computer modelling for design verification. Training simulators for crew and harbour personnel, custom on-board measurement equipment and commercial software modules for maritime applications are further examples of how MARIN uses its know-how to support the industry.

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6 Providing Exceptional Facilities To fulfil its design and verification services, MARIN has an exceptional range of model testing, computer simulation, full-scale measurement and training facilities. The synergy between these activities is the basis of our problem solving capacity, aiming at a reliable prediction. We have seven tank facilities available to solve specific design and research issues. Seakeeping and Manoeuvring Basin Verifying performance and safety requires accurate representation of a ship and its ride control elements in relevant wave conditions. Our Seakeeping and Manoeuvring Basin (170 x 40 m) is designed for making arbitrary (high-speed) manoeuvres in realistic waves from arbitrary directions. The free-sailing or captive tests provide insight into the seakeeping and manoeuvring characteristics. Offshore Basin The Offshore Basin (10.2 m deep) is a realistic environment for testing offshore models. Its current generation system allows different vertical current profiles. Combined wind, waves and swell are generated using wave generators on both sides of the basin and a movable windbed. A movable floor allows testing from shallow to deep water, while a 30 m deep pit is available for ultra deep water testing. High-speed Basin With its strong carriage and long length (220 m), the High-speed Basin is an ideal test facility for testing high-speed vessels but also for testing risers at high Reynold s numbers. The performance of high-speed vessels with conventional propellers, water jets or hybrid solutions can be optimised. Tests are conducted in ahead and in astern wave conditions. A special set-up is available for forced oscillation tests to study vortex-induced vibrations (VIV). 6

7 Deepwater Towing Tank The Deepwater Towing Tank (252 x 10.5 x 5.5 m) is used to optimize resistance and propulsion characteristics of ship designs. To provide insight in the possible improvements in performance the tank has the features to measure various wave and flow patterns. In addition to the standard resistance and propulsion tests the rudder or pod angle, pod position and propeller rotation direction can be optimised. Shallow Water Basin The depth of the Shallow Water Basin (220 x m) is adjustable from 0 to 1.15 m. It is used to optimise the propulsion characteristics of ships as well as the (low speed) manoeuvring behaviour in shallow water. This including factors like proximity of quays and bank suction. The test can be used as input for simulations which help to optimise nautical strategies. The facility is also used for Concept Development and Design Support of new offshore designs in shallow water. Depressurised Wave Basin Models of both ships and offshore structures can be tested in most realistic operational conditions in the Depressurised Wave Basin (240 x 18 x 8 m). The basin can be used for resistance and propulsion tests. The capability to reduce ambient air pressure as low as 2,5% of atmospheric pressure and installed wave makers for short and long crested waves up to 0.75 m, makes it ideal for investigations into cavitation, air chambers and wave impacts with air entrapment. Cavitation Tunnel The Cavitation Tunnel tests a range of propulsor designs. Large propellers can be tested at high Reynolds numbers to predict accurate cavitation behaviour. A tunnel loop is available to test the performance and cavitation properties of water jet impellers. Observation with high-speed cameras enables detailed cavitation flow investigations. 7

8 Simulating Reality, Measuring Results In combination with the model tank facilities, MARIN uses simulation software, full-scale testing and training. This strong combination is used to achieve reliable prediction of the performance in the design phases but also to improve and ensure the optimal operational use of the ship or structure. Full-mission Bridge Simulators By simulating the port environment and the vessel, personnel such as captains, pilots, mooring masters and tug masters can demonstrate the feasibility of a port layout in terms of safety and viability. Full-mission Bridge Simulators are also used for reducing risk and downtime in (offshore) operations by training manoeuvring and communication skills, or by optimising manoeuvring strategies, port layouts and vessel designs. CFD Software Computational Fluid Dynamics (CFD) tools provide a cost and time effective method for optimising the design in the early design phase or addressing scale effects. MARIN uses CFD tools to optimise hydrodynamic hull design, provide information about flow behaviour around hull and propeller under various conditions, and predict propeller performance in open water and in-behind conditions. Ship Trial Investigations MARIN not only conducts sea trial measurements but also performs in-situ analysis of vibration and cavitation properties by, for example, high-speed video observation of propellers while recording dynamic hull pressures and vibrations. Laser Doppler and acoustic Doppler technology are used to investigate flow patterns around the hull. Slamming and whipping, and their contribution to (fatigue) loading of the vessel, are also investigated. 8

9 Dynamic Stability Simulation Software The dynamic stability of ships in waves and wind is investigated during early design stages using programs that also performs risk assessment into longterm survivability of (damaged) ships. These programs simulate the behaviour of a steered ship subjected to wave and wind conditions, and can predict large motion phenomena such as capsizing, broaching, surf riding, parametric roll and ingress of water. This also has applications in forensic research. VTS Simulator Vessel Traffic Services (VTS) are the acknowledged starting point for effective vessel traffic management systems in ports and busy shipping traffic lanes. The MARIN VTS Simulator facilitates personnel training and explores the future management of large traffic flows in ports avoiding congestion and improving the port s safety, security and viability (efficiency). Offshore Monitoring Systems Continuous recording of dynamic behaviour of offshore platforms is critical for operational support, design feedback and verification of numerical methods. The MARIN data acquisition system accommodates sensor sets for motion, hull strains, mooring and riser tensions and VIV motions. System control and results are accessible through the Internet for a global service approach to the offshore and shipping industry. Offshore Multi-body Software The Offshore Multi-body tools simulate operations at sea, including coupled mooring analysis, dynamic positioning, multiple body simulations during offshore lifting or offloading. These capabilities can be linked to each other, for example, to determine dynamic positioning capabilities during offshore lifting. This type of tool is always based on the model basin experience of MARIN, ensuring validation remains a top priority. 9

10 Working Practices, Doing Business (1) Oasis of the Seas 10 It was MARIN s long-standing relationship with Finish shipyard, STX Europe, that led to its early involvement in the design and development of the world s largest cruise liner: Royal Caribbean International s Oasis of the Seas. Measuring over 225,000 gross tons the challenge was to meet the stringent performance requirements set for this 360 metre-plus, revolutionary vessel, to ensure safety, comfort and efficiency. Flexural response in seaway It was important to quantify and judge the slamming-induced flexural response of the ship early on. Wave-induced impact pressures were measured on large 12 metre models using seventy pressure gauges. By associating each pressure with an area and orientation, STX Europe was able to use the resulting data to produce dynamic, finite-element calculations on the structural vibrations. These calculations were compared to the shipyard s continuous measurements at sea on a similar, but smaller, cruise liner, and the correlation was excellent. The results were also validated successfully against the direct measurements of a segmented, 7-metre, free-sailing model. In this model, the vertical and horizontal 2- and 3-node bending modes and first torsion mode, were modelled with a simple, flexible backbone. Slamming-induced passenger discomfort, flexural response and global horizontal & vertical bending and torsion moments were all measured. Manoeuvrability With frequent calls to harbours, tight bays and restricted channels, the gigantic Oasis was obliged to be as responsive as any normal sized cruise liner. Large-scale model testing and MARIN s computer simulation tools were used to evaluate this. Measurements determined the effect on Oasis of 60MW main propulsion power and 22MW bow thruster power, and a channel was modelled in MARIN s Shallow Water Basin to mimic real life. With fast-time simulations, manoeuvring capability was tested for 20 harbours. Personnel also carried out critical manoeuvres in confined waters on the Full-mission Bridge Simulator. MARIN s Seakeeping & Manoeuvring Basin was used to perform free-sailing model tests to determine manoeuvrability at cruising speeds. Vibration Customer comfort is paramount to any cruise line, and the propeller is always of vital concern. Propeller-induced pressure pulses can send vibrations throughout a vessel structure, and with this in mind, MARIN teamed up with Oasis s propeller designer to optimize the design, both for comfort and efficiency. The resulting design was put through its paces in MARIN s Depressurised Towing Tank which modelled the entire ship, and checked on cavitation behaviour and induced pressure pulses. Specific criteria were developed to check if the propeller-induced forces on the hull were acceptable or not. And to verify the stringent requirements for Oasis, full-scale measurements were carried out. Speed and fuel consumption Efficiency is more important today than ever before. MARIN s Computational Fluid Dynamics (CFD) tools were employed to streamline Oasis s hull and appendages, and performance was validated and fine-tuned using model testing. MARIN was also able to build on its broad experience with other pod-propelled cruise liners, utilising an already researched, pod scale-effect correction method for Oasis. The commitment of Royal Caribbean International, STX Europe and the engineering team, to optimize the design and build of Oasis of the Seas, has yielded unprecedented results, and MARIN is honoured to have been involved. The project demanded state-of-the-art numerical optimisation tools and advanced measurement techniques attributes for which MARIN has become renowned. But there is no better proof of the success of this project than the ship itself. Oasis of the Seas has achieved positive passenger feedback ever since her maiden voyage, and is noted for her stability and performance.

11 Final trials verified the results from MARIN simulation and model experiments 11

12 12 The Offshore Basin s 30 metre deep pit enables TLP testing at full tendon length

13 Working Practices, Doing Business (2) Tension Leg Platforms (TLPs) The first TLPs were tested at MARIN in the early 1980s. After the current Offshore Basin, with its deep pit, was put into operation, MARIN s level of knowledge and experience with this type of structure increased exponentially. Many complex hydrodynamic phenomena play a role in the design of TLPs, such as non-linear wave loads, dynamic tendon loads, vortex-induced vibrations (VIV) and vortexinduced motions (VIM), relative wave motions and possible deck impacts. MARIN s broad range of services and expertise covers all these aspects. As a result, we have welcomed many TLPs for testing at our facilities in the past decade, including the Snorre, Okume, Shenzi, Pony and Big Foot TLPs. Unique model testing capabilities The Offshore Basin is a unique model testing facility with state-of-the-art capabilities for simulating waves, currents and wind. The basin s 30 metre deep pit is of particular importance for the model testing of deep-water TLPs because it enables the full TLP mooring system to be tested without having to truncate the tendons. Simulating the full tendon length is essential for TLPs as it means that important aspects such as platform set-down and air-gap can be modelled correctly. Extreme wave loads Model testing of TLPs often includes tests in extreme environments. This requires knowledge of extreme wave conditions, as well as the ability to realistically scale these extreme wave conditions in the model basin. Measuring relative wave motions, air-gap and deck impact loads reliably is a complex task that requires an integrated design of the model and its instrumentation. In-house 3D CAD software enables MARIN to accurately design and construct the most complex platforms in great detail. In addition, high-speed video recording and computational fluid dynamics (CFD) are used to understand complex flow phenomena around and between the platform s columns. Current loads and VIM In strong currents a TLP may show vortex-induced motions (VIM), which can play an important role in designing the platform. VIM manifests itself based on the current velocity, current direction and natural periods of the platform. MARIN has developed a special set-up for VIM tests on TLPs by using ultra-low-friction, air-lubricated bearings to apply vertical pretension to the model. This approach means that VIM tests can be conducted in a towing basin with a perfectly constant current, while at the same time the correct platform mass and displacement can be maintained. Research into the possibility of calculating VIM using CFD is still ongoing. Full-scale measurements Measuring platform motions, structural loads, and tendon and riser tensions on board an offshore structure requires specialised knowledge and equipment. MARIN provides the services required to monitor platforms over their operational lifespan. A case in point is the Marco Polo TLP, on which MARIN successfully recorded extreme conditions resulting from phenomena such as hurricane Ivan and loop current events. Besides these activities, MARIN is also dedicating a number of research projects to issues related to the hydrodynamics of TLPs. These projects include the Current Affairs Joint Industry Project, which focuses on the current loads on offshore structures, the ComFLOW Joint Industry Projects, through which a tool for volume of fluid (VOF) calculations was developed, and the ongoing development of ReFRESCO, MARIN s in-house CFD code. Finally, the CresT Joint Industry Project investigated the properties of extreme wave conditions at sea and in model basins, as well as the TLP motion response and resulting tension loads. 13

14 Sharing Experiences and Building Knowledge In addition to providing commercial hydrodynamic design and verification services to industry and governments, MARIN s contribution to shaping tomorrow s products also takes place through fundamental research, cooperative research in international networks and Joint Industry Projects. By sharing experiences through training and seminars at our facility in the Netherlands, the common knowledge base continues to grow. Transfer of theoretic knowledge to real applications MARIN views Joint Industry Projects (JIP) as one of the most important steps in the development, sharing and application of knowledge. The cycle starts with the development of fundamental knowledge and scientific research in cooperation with universities. The JIP promotes the transfer of theoretic knowledge to concrete applications in industry, and combines customer contact, market-driven research and the development of practical tools. Pooling resources at a pre-competitive level, all parties enjoy the cost savings of shared investment and benefit from research they could not afford alone. Joint Industry Projects form a significant part of MARIN s business. Cooperative Research MARIN s role in the development of maritime knowledge is shared with the market through participation in forums such as the Cooperative Research Ships (CRS), the Cooperative Research Navies (CRNAV) and the FPSO Research Forum. Participating in thematic networks and forums within the framework of European initiatives and regulations enhances interaction with customers and with the marketplace as a whole, facilitating a broader translation of our fundamental and theoretical know-how into real-life applications. Fundamental research Fundamental research and technology development is crucial for MARIN in order to maintain a leading position in hydrodynamics, and supporting the maritime industry as a whole. For such extensive research, MARIN cooperates with other institutes, universities and organizations in the Netherlands and overseas. Training and seminars Other important carriers for transferring MARIN s expertise and knowledge are training and seminars. Courses for designers and architects are held periodically throughout the year. To increase interaction with the market, MARIN also organises seminars that bring together groups of customers with common design issues to discuss possible solutions. 14

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