Naval Group and Centrale Nantes have printed the first demonstrator of hollow propeller blades by metal additive manufacturing as part of the European H2020 project, RAMSSES (Realization and Demonstration of Advanced Material Solutions for Sustainable and Efficient Ships).
Funded by the European Commission, this collaborative program aims to reduce the environmental impact of ships. Centrale Nantes and Naval Group are taking the lead within this project on the production of innovative propeller demonstrators to improve the operational capabilities of ships.
In order to improve vessel propulsion, Centrale Nantes and Naval Group are using additive manufacturing to design large parts (propellers of 6 meters in diameter), which could not be produced thus far using traditional manufacturing technologies.
Design example of a hollow propeller.
Implementing the Wire Arc for Additive Manufacturing (WAAM) process allows for the printing of large parts and paves the way for the production of propellers with more complex geometry. WAAM uses an electric arc as a heat source and wire—rather than powder—as feedstock.
The demonstrator propeller blade foresees development and proof of feasibility of a WAAM process using different metal alloys, e.g. cupro-aluminium, martensitic or duplex steels.
The one-third scale hollow blade demonstrator, representative of a container ship propeller, was printed in stainless steel in less than one hundred hours, weighing in at about 300 kg. Weight gains of more than 40% will be achievable compared to conventional processes.
Sirehna, a Centrale Nantes spin-off and subsidiary of Naval Group, is piloting the blade design in order to improve propeller energy efficiency and reduce their environmental impact. Sirehna’s work has led to an overall optimization of blades in terms of efficiency and endurance, but also a significant reduction in radiated noise and vibrations.
Reducing the environmental footprint linked to propulsion, as demonstrated in the H2020 RAMSSES project case study, is a challenge for all types of vessels, and particularly for large container ships.
Naval Group and Sirehna have been able to count on the technical resources and extensive knowledge offered by Centrale Nantes. The school’s expertise in trajectory generation and additive manufacturing is needed to produce the blade. This long-standing co-operation, which took on a formal footing in 2016 with the creation of a joint laboratory (JMLT), feeds through to control over the entire digital chain from design to mechanical dimensioning and hydrodynamics to manufacturing, and will lead to the production of a complete propeller.
RAMSSES is a 48-month program with 21 work packages and 37 partners from 12 countries, marked by the presence of the main shipyards (Damen, Meyer Werft, Chantiers de l’Atlantique, Naval Group…) and European maritime research laboratories (including TNO in Netherland and the Research Institute of Sweden).
Created in 2016, the JLMT is a joint laboratory in industry and research which the general objective is to mobilize academic and industrial skills of Centrale Nantes, Nantes University and Naval Group in order to result in qualified innovation for Naval Group’s industrial applications in the field of naval construction.