France’s Centre de Recherche pour l’Architecture et l’Industrie Nautiques (CRAIN) Technologies has secured approval in principle (AiP) from fellow class society Bureau Veritas (BV) for its auxiliary wind propulsion device for cargo ships.
The suction wing concept, named SW270, is a solid thick wing, fitted with a rear flap, jointly developed by Crain and its partner REEL (Rationnel Economique Esthétique Léger). Grids located on both sides of the wing section create a suction force that draws the air stream around the wing section from the outside to the inside of the wing. The wing is mounted on a structural foundation that contains the suction fan required to operate the system.
The suction wing concept is said to deliver a very high lift coefficient, which reduces the size of the device needed to achieve a given pull force.
“Thanks to the shape of the system, the drag remains moderate. Therefore, the lift-to-drag ratio provides a good performance in upwind conditions and for ships sailing at relatively high speeds, using the wind to propel the ship in combination with the main engine,” said BV.
The wing section can rotate around a vertical axis to adjust to the wind direction and optimise performance. The device considered in this AiP was a wing with a span of 27 m, but BV noted the concept could be derived in a range of sizes to fit various vessel sizes.
“Suction Wing SW270 is an innovative wind-assisted propulsion solution that is suited for a large range of cargo ships. Developed using technologies already widely used by the naval industry, it delivers great power proportionally to its surface and is easy to install and use on ships, stated Philippe Pallu De Barriere, CEO of CRAIN, adding that the collaboration with BV enables it “to move on to the next step, providing specifications for the industrialization of SW270 by our partner.”