Leanships project achieves fuel savings applying pre-swirl stator to CPPs

The power-saving device, comprising three fins connected by an outer ring to eliminate tip vortexes, optimises the inflow of water to the propeller to reduce power losses. The concept guides one side of the stern flow in the opposite direction to the propeller rotation, optimising the flow into the propeller and preventing power losses. The technical challenge was how to optimise the pre-swirl stator for the effects of a CPP’s variable pitch on the swirl generated.

Following model tests, and subsequent sea trials with Grimaldi’s Grande Portogallo, a 165m-long Pure Car & Truck Carrier, fuel efficiency gains of 3.5% were confirmed. This translates into a pay-back period of only 1.3 years. According to Grimaldi “The initial noon reports suggest a 5 percent decrease in the fuel consumption, but in order to get a more realistic value we need to record a wider range of data”.

“Wärtsilä continues to collaborate with strategic partners to create greater efficiencies that enable both cost savings and better environmental performance. The Energy Saving Device developed through the LeanShips project is one more example of successful collaboration that results in substantial customer benefits,” says Lars Anderson, Director, Propulsion, Wärtsilä Marine.

The work was carried out as part of the LeanShips project, under the European Union’s Horizon 2020 framework project for research and innovation. LeanShips aims at demonstrating the effectiveness and reliability of technologies that offer energy savings and emission reductions on a large scale. LeanShips was a four-year project and was completed in April 2019.

Wärtsilä and MARIN were earlier involved in the GRIP project, funded by the European Commission under the 7th Framework programme, which successfully designed and optimised ESDs for ships fitted with Fixed Pitch Propellers (FPPs). This resulted in full-scale demonstrations that achieved a nearly 7 percent reduction in the required power of a bulk carrier vessel. Wärtsilä subsequently launched a pre-swirl stator product, EnergoFlow, aimed at fixed pitch propellers in 2017.

The completed programme showcases a successfully demonstrated case regarding design, installation, strength and load resistance, which fulfils the purpose of achieving efficiency improvement.