Prognosis of Propeller-Induced Pressure Fluctuations on the Ship's Hull

Motivation and Outline

Propeller-induced pressure fluctuations may be a crucial factor in the entire ship design process of certain ship types. Thus, it is important to develop fast and reliable methods for the prediction of these pressure fluctuations.

The flow in the aftship region is dominated by two interacting parts: The wake field of the ship, which is strongly influenced by viscous effects and the flow around the propeller, which basically has the character of an unsteady potential flow. Viscous methods, such as RANS methods, are able to cover all these effects, but this is far away from practice with respect to the integration of such computations in the ship design process.

We want to focus on a different approach, based on a combination of RANS methods and potential-theory based methods: The propeller and relevant parts of the ship's hull are modelled with a potential-theory based method (in this case our panel code panMARE). Simultaneously, a RANS method (in this case our in-house code FreSCo+) is running only containing the hull geometry.

Coupling Scheme

Figure 1: Coupled Calculation for the Prediction of Pressure Fluctuations.

Figure 1 demonstrates the principle: The effective wake field is calculated by the RANS method and passed to panMARE as input. The influence of the propeller in the RANS domain is simulated by a body-force approach based propeller model using the pressure distribution calculated by panMARE.

The pressure fluctuations can be taken from the panel code domain. Furthermore, sheet cavitation effects can be captured. For this purpose, only the panel code has to be enhanced.


Type of Project and Extent

We plan two student projects about this theme: One dealing with the correct mathematical formulation and the implementation of the presented method (Diploma or Master Thesis), and a second one dealing with the systematic validation of the model (Bachelor Thesis or "Studienarbeit").


Requirements

Knowledge in hydrodynamics and CFD as well as coding experiences (C, C++ and Perl or Python).


Contact

For more information please get in touch with:

Prof. Dr.-Ing. Moustafa Abdel-Maksoud
Dipl.-Ing. Stephan Berger