GAGGERO S.

A simulation-based design optimization (SBDO) tool is proposed for the design of rim driven thrusters. The optimization framework consists of a parametric description of the rim blade geometry and a multi-objective optimization algorithm which makes use of the results from high-fidelity RANS calculations to drive the choice towards optimal...

RIM driven propellers represent an unconventional, but underrated, propulsive solution which hydrodynamic design is still not obvious. In the last years, most of the attention has been devoted to the efficient coupling with electric motors, since only recently the development of permanent magnets allowed for the successful embedding of the...

The numerical study presented in Part I (Gaggero, 2020), focused on the prediction of the laminar-to-turbulent boundary layer transition on model scale propellers, is extended to cavitating conditions. In the previous study, the application of the γ-Reθ Local Correlation Transition Model allowed for significant improvements in model scale...

The influence of the laminar-to-turbulent boundary layer transition on model scale propellers characteristics is investigated using the γ-Reθ model. OpenFOAM and StarCCM+ RANSE solversare used for the investigation, which is carried out for two test cases. Available measurements at a sufficiently low rate of shaft revolution (i.e. Reynolds...

In this paper, after the successful applications to open water propeller performance estimations, the influence of transition sensitive and modified mass transfer models tuned to account for the laminar flow in the prediction of the cavitation inception of marine propulsors is investigated from the point of view of the unsteady functioning and...

Achieving a reliable and accurate numerical prediction of the self-propulsion performance of a ship is still an open problem that poses some relevant issues. Several CFD methods, ranging from boundary element methods (BEM) to higher-fidelity viscous Reynolds averaged Navier–Stokes (RANS) based solvers, can be used to accurately analyze the...

In the last years, an increasing attention has been devoted to ships Underwater Radiated Noise (URN), with the progressive introduction of Guidelines by international organizations such as IMO, Classification Societies voluntary notations, limits and incentives in specific areas. In this context, a large effort has been spent in the study of...

Tip loading is a common strategy to increase the propulsive efficiency of propellers. Solutions such as contracted and tip-loaded (CLT) and "New generation" CLT propellers exploit the presence of an endplate ("true" or as the result of a dedicated modification of the rake distribution) to sustain the increased load at the tip of the blade, at...

A design method for pre-swirl stators energy saving devices, using a combined BEM-RANSE approach, is proposed. RANSE calculations, using actuator disks, are employed to provide the required thrust and the effective wake to an unsteady Boundary Element Method through which the rate of revolution of the propeller and its averaged performance in...

Pre- and post-swirl fins-based energy-saving devices (ESD) are designed to improve the propulsive performances of a twin-screw ship. To this aim, BEM and RANSE calculations are employed. Depending on the application, a simple actuator disc model (post-swirl) with radially varying load or a combined BEM/RANSE method for self-propulsion...

The performances of different Propeller Boss Cap Fins devices, designed with the aid of a Simulation Based Design Optimization approach, are analysed and compared. A novel configuration, i.e., a PBCF inside a nozzle, is investigated in an effort to mitigate possible side effects of conventional Propeller Boss Cap Fins, such as secondary...

Pre-swirl fins-based energy saving devices (ESDs) have been designed to improve the propulsive performances of twin-screw ships. To this aim, a combined BEM/RANSE method for efficient self-propulsion prediction is required. The approach is included in a framework for a design by optimization, where systematic variations of the ESD geometry have...

Simulation-driven shape optimisation (SDSO) of marine propellers is often obstructed by high-dimensional design spaces stemming from its complex geometry and baseline parameterisation, which leads to the notorious curse of dimensionality. In this study, we propose using the shape-supervised dimension reduction (SSDR) approach to expedite the...