Numerical simulation of propeller-hull interaction and determination of the effective wake field using a hybrid RANS-BEM approach

In this study propeller-hull interaction is investigated numerically using a combination of a steady viscous CFD method (RANS) for the ship flow and an unsteady potential-flow method (BEM) for the propeller loading. This approach allows for interaction between hull and propeller with a significantly reduced computational effort compared to a full RANS approach. In addition, the RANS-BEM coupling provides the propeller designer with an effective wake field. RANS-BEM results for self-propulsion are obtained with two different RANS solvers. The computations show a prediction of propeller rotation rate and thrust within 2 to 3% of the experimental values. It is demonstrated that the effective wake accelerates towards the propeller. Therefore the essential part of the RANS-BEM coupling remains how and where to determine the effective wake field. The influence on the propeller performance is shown by evaluating effective wake fields at different planes upstream of the propeller. Extrapolating the effective wake field to the propeller plane using multiple planes upstream results in an increase of about 2 to 3% in predicted rotation rate compared to using a single plane upstream.