On the benefits of metallic additive manufacturing for propellers

While ship propellers have little changed over the past decades, the simultaneous development of advanced numerical simulations and additive manufacturing technology unveils new perspectives. The manufacturing process offers new design freedom with possible improvement of direct and transverse propeller performances such as reduction of mass, reduction of power consumption or better acoustic performances. Naval Group has very early sensed the advantages of these technologies applied to propellers and decided to work on them. Today, Naval Group has developed a technological expertise all along the process, from the design using numerical tools, through the process simulation, up to the realisation of a demo hollow blade. This paper focuses on the development of a global numerical tool chain and its application to a hollow propeller concept optimisation, which has later been actually manufactured. The design tools consist of a set of methods and software able to compute propeller performances, automate the design process and achieve better performances with the help of optimisation environments and algorithms. The application case is a propeller with hollow blades, potentially extremely complex or even impossible to build with a classical foundry process. This paper emphasises the new paradigm that is offered to the designer and how this manufacturing process can contribute to better performances of propellers for the benefits of energy savings, cavitation improvement, and noise and vibrations reduction