Using modeFRONTIER to perform multi-objective cavitating propeller optimization
The design of a propeller is always a trade-off between competing objectives and constraints: maximizing the propulsion efficiency and ship speed while avoiding cavitation and maintaining a sufficient blade strength. The traditional lifting line/surface methodologies define the propeller shape by including simplified geometric assumptions that make them not suitable for modern fast propellers design. The application of more accurate flow solvers and the automatic investigation, possible through the parametric description of the geometry (unconventional combinations of pitch, camber, or, for instance, local hydrofoil shapes), proves to be a successful design alternative for a high-speed propeller.
A dedicated full-scale sea trials performed with propellers manufactured by Detra showed that the cruise speed achieved with the optimized propeller is 1 kn higher than the baseline propeller speed, geometry by while the cavitating behavior was also significantly enhanced. “The result is remarkable, especially keeping in mind that the increase of cruise speed, together with the enhancement of comfort onboard, is crucial to the perception of luxury yacht customers”, said Francesco Serra, R&D Office, Azimut Benetti Group
“modeFRONTIER helped increase cruise speed and reduce cavitation in marine propellers."
Francesco Serra, R&D Office, Azimut Benetti Group
modeFRONTIER helped build an optimization framework to interact with the parametric description of the geometry to define each new blade shape and employ flow solvers to quantify how each propeller fulfills the constraints and the objectives of the design. “Starting from a set of 48 blade parameters to alter the reference propeller geometry, the use of MOGA-II algorithm allowed to compute and test 50,000 different geometries in about 5 days to achieve a satisfactory Pareto convergence and choose optimal candidates (one for any rake distribution) for RANSE analyses” said Michele Viviani, Associated Professor at DITEN Department, Genoa University.
About Azimut Benetti
Azimut Benetti Group is the largest network producing mega yachts and the world’s leading private group in the luxury yachting industry. The Company operates and produces in its 6 shipyards and with more than 40 models in production, the two brands Azimut e Benetti offer the broadest range in the world. The group accompanies its manufacturing excellence with a particular focus on services for its customers, offering financial services, designing, planning and building new tourist marinas, providing customers with a luxury showroom, and training crews.