Hydroelastic simulation of the acoustic behaviour of ship-propeller configurations with and without cavitation
AB 112/12-2, DU 405/13-2
Recently, noise pollution in the oceans due to ships has raised a lot of attention from the corresponding authorities. It is expected that the shipbuilding industry will have to take according actions - already at the design stage - for the sake of noise reduction, and also to comply with respective regulations that are expected in the near future.Having developed a numerical simulation approach that allows for a detailed investigation of the acoustic signature of flexible marine propellers in the first phase of the project, we aim to employ this approach in the scope of an optimization algorithm in the second phase of the project. The developed partitioned coupling of boundary elements (for the fluid sub-problem) and high-order finite elements (for the structural sub-problem) in combination with an acoustic evaluation based on the Ffowcs Williams-Hawking equation yields very efficient simulations. However, the fully coupled solution approach is still too costly to be used directly for optimization purposes. Accordingly, the focus of the second phase lies on the development of a suitable optimization process that incorporates uncoupled simulations, which will greatly reduce the computation time. Further, we plan to consider composite materials, as they offer a higher flexibility when designing propellers with passively adaptive deformation behavior that reduces the radiated noise.Accordingly, we aim at a multi-stage optimization process, where in a first stage, uncoupled hydrodynamic simulations are used to find optimal deformed shapes for propellers without actually considering their dynamic behavior. In a second stage, uncoupled structural simulations shall be used to find an initial propeller configuration (shape and composite structure), which yields the deformed shapes from the first stage when the hydrodynamic loads are applied. These two stages yield suitable initial guesses for a final stage, where coupled FSI simulations are used to further optimize the initial propeller configuration.