FDS > Research > Ongoing Projects > Hydroelastic simulation of the acoustic behaviour of ship-propeller configurations with and without cavitation

Hydroelastic simulation of the acoustic behaviour of ship-propeller configurations with and without cavitation

Background

Related to environmental concerns and associated legislative developments, one of the marine industry’s main areas of interest in the near future will be the control and limitation of ship noises. The major source of noise propagation from ships is attributed to the propulsion system. Ship propellers pose unique challenges due to the high unsteady loads acting on the propeller blades and additional phenomena such as cavitation and erosion which not only increases acoustic emissions but also compromise the life span. In this work, a propeller geometry is optimized regarding its hydroelastic and acoustic behaviour in order to improve the environmental footprint and low operating costs.

Objective

In the frame of this, a partitioned simulation approach is applied for the accurate computation of the fluid-structure interaction (FSI) problem. Within the partitioned approach, the fluid and the structural part are solved in a strongly coupled solution algorithm, i.e. both fields are solved multiple times in every time step until convergence of the coupling quantities at the interface between the fluid and the structure domain is obtained. The fluid part of the FSI is simulated using the panel method implemented in panMARE [1] while the structural simulation is conducted with the Finite Element Method (FEM) using the commercial software Ansys [2]. Latter is conducted by the collaborating Institute for Ship Structural Design and Analysis which also provides the in-house developed coupling framework comana [3].

Figure 1: Optimization of propeller blade considering the ship wake field

Figure 2: Hydroacustic evaluation of a pulsating under water sphere.

The outcome of the panel method panMARE is used to evaluate important operational parameters such as thrust, efficiency, and acoustic emissions in realistic operation conditions. For the evaulation of the acoustic behaviour, the Ffowcs Williams-Hawkings equation (FWHE) are integrated into the boundary element method. Based on these output parameters the shape of the propeller is optimised. The automatic generation of the geometric shape of the propeller is carried out with the software library Hykops [4], which was developed for this purpose. Based on a few selected input parameters like pitch, chord length and skew, the geometry and the mesh for the fluid and the structural part of the propeller are generated automatically.

Figure 3: Propeller blad in cavitating open water conditions and under consideration of its deformation.

Cooperation

Our partners in the joint research project is Hamburg University of Technology's Institute for Ship Structural Design and Analysis .

Funding

This project is funded by the Deutsche Forschungsgemeinschaft e.V.

Personnel

Daniel Ferreira González, Prof. Dr.-Ing. Moustafa Abdel-Maksoud

References

[1] M. Bauer and M. Abdel-Maksoud, “A 3-d potential based boundary element method for the modelling and simulation of marine propeller flows”, 7th Vienna Conference on Mathematical Modelling, 2012.

[2] ANSYS Academic Research Mechanical, Release 19.2. ANSYS, Inc., Southpointe, USA, 2017.

[3] M. König, L. Radtke and A. Düster, “A flexible C++ framework for the efficient solution of strongly coupled multifield problems”, Computers & Mathematics with Applications, Vol. 72.7, pp. 1764-1789, 2016.

[4] E. Praefke, T. Stoye and C. Abt, "A generalized description of hydrodynamic parts based on aerodynamic profile sections", 5th International Symposium on Marine Propulsors, Espoo, Finland, 2017.