A twist in the tail: DNV GL adds asymmetric stern to ECO Lines hull optimization servic

Tuesday, 09 May 2017


Hamburg, A vessel with an asymmetric stern has a twisted aft shape that is designed to account for the differing flow conditions on each side of the propeller. The idea emerged in the 1960s, but due to the difficulty of manually developing the optimal shape, this design failed to make a large impact at the time. DNV GL has revisited the idea and, using high-fidelity computer fluid dynamics (CFD) in combination with parametric formal optimization, the classification society can now offer ship owners the option of incorporating an asymmetric stern into their new vessels.      

“Basically, what we are now able to do is model an aft shape that acts as a propulsion improving device, without the vibration and fatigue strength concerns that come with fins and nozzles,” says Karsten Hochkirch, Head of Department, Fluid Engineering at DNV GL – Maritime. “Using our in-house formal parametric optimization procedure, we can assess hundreds of options until we find a design that strikes an optimal balance between pre-swirl and resistance, while meeting the design requirements of the customer.”

In a recent project, a 3,000 TEU container ship was tuned to achieve minimum power consumption. Starting from a well-optimized symmetric baseline design, the asymmetric design achieved a propulsion power reduction of more than 3%, a result that was confirmed in tank testing. In another project, the ECO Lines team was asked to find propulsion efficiencies in a 38,000 DWT tanker. The CFD optimization generated a design promising a 3.5% percent decrease in propulsion power compared to the symmetrical design.

“This is another instance where advances in computing power and software sophistication are enabling us to unlock efficiencies in ship design. By accurately simulating the performance of these complex hull forms, we are achieving propulsion power improvements of up to 5%, with greater structural robustness,” says Karsten Hochkirch. “And because yards are now able to utilise advanced CAD/CAM techniques and modern, CNC-controlled fabrication methods, they can bring these designs into production much more easily and economically.”

You can find more high resolution images and information about the possibilities of the asymmetric stern design here.

About DNV GL

Driven by our purpose of safeguarding life, property and the environment, DNV GL enables organizations to advance the safety and sustainability of their business. We provide classification, technical assurance, software and independent expert advisory services to the maritime, oil & gas and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our professionals are dedicated to helping our customers make the world safer, smarter and greener.

About DNV GL – Maritime

DNV GL is the world’s leading classification society and a recognized advisor for the maritime industry. We enhance safety, quality, energy efficiency and environmental performance of the global shipping industry – across all vessel types and offshore structures. We invest heavily in research and development to find solutions, together with the industry, that address strategic, operational or regulatory challenges. For more information visit www.dnvgl.com/maritime

Media contact DNV GL:
Nikos Späth, Head of Media and Public Relations
DNV GL Maritime Communications
Tel.: +49 (0)40/36149-4856
E-Mail:
nikos.spaeth@dnvgl.com

 

News Presented by Cathy McLean

 Carousel centre page advertising for $42.50 Calendar Month.!!!

 Details  http://www.bymnews.com/demo/display-carousel.html