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Classification society The American Bureau of Shipping (ABS) and the Shanghai Merchant Ship Design & Research Institute (SDARI) have entered into a two-year joint research and development project to study the potential of an energy-saving device that would enhance propulsion efficiency on a bulk carrier.

With environmental issues becoming the most important operating issue facing the shipping industry today, the study is timely in that an add-on device could offer shipowners the potential to reduce greenhouse gases through lower fuel consumption due to increased propeller efficiency.

“We will use computational fluid dynamics (CFD) technology to analyze the flow field and will specifically look to see if the device developed by SDARI does indeed create more efficiency by equalizing the wake quality and recovering certain rotation energy,” explained Sing Kwan Lee, ABS Principal Engineer, Shared Technology who is managing the class society’s participation in the project.

Lee is recognized by the industry for his work in the area of propeller and propulsion designs and ABS’ Technology group is renowned for its leading edge CFD applications in the marine industry.

According to Lee, it is the expectation that the analysis will confirm a three to four percent increase in efficiency with the use of the device placed in front of the propeller. With this expected range of efficiency and using data published in a second IMO Greenhouse Gas Study in 2009, a capesize bulk carrier could save between 450 to 760 tons of fuel in a one-year period, ABS said.

There are many different ways in which energy is lost, thus reducing efficiency. For example, friction resistance, wave resistance, propeller friction and propeller axial or swirl flow loss.

“Wave resistance is just one part of the total resistance,” explained Lee. “Even if a large reduction of wave resistance through hull optimization can be achieved, this won’t bring significant impact to the energy-saving propulsion. The dominant resistance of a full form ship, like a bulk carrier, is mainly due to the viscous resistance.” Therefore, the study concentrates on using some of the most sophisticated CFD techniques including the Reynolds-averaged Navier-Stokes (RANS) computation to create very detailed flow characteristics in order to study and assess the suitability of the design device.

“The detailed flow field obtained from CFD simulation will be essential design information for selecting the type of energy-saving device and locating it to an appropriate position,” Lee added.

The study will evaluate the design device based not only from a resistance standpoint but also from a more holistic propeller/hull/rudder interaction optimization perspective. It will be conducted in two phases: phase one will focus on analysis and design while phase two will focus on model testing of the device.