Investigation on hull-propeller-rudder interaction by RANS simulation of captive model tests for a twin-screw ship

The hull-propeller-rudder interaction of a twin-screw ship is investigated by using CFD method. The hydrodynamic performances of propeller and rudder during maneuvers are analyzed based on the relevant modules in MMG model, with the propeller side force and asymmetric flow-straightening effect being taken into account. Taking the ONR tumblehome ship model as the study object, self-propulsion test, rudder force test, circular motion test, and static drift test are simulated by using RANS method. The interaction coefficients among the hull, propeller, and rudder, as well as the models of propeller side force and rudder normal force are obtained from the computed hydrodynamic forces and moments. The obtained parameters in the modules show reasonable agreement with the available experimental data. The velocity field around the stern and the pressure distribution on the rudder surface are presented to provide deeper insight into the effects of ship motion and propeller load on the rudder performance. The turning circle test is simulated using the obtained hydrodynamic modules. The simulated trajectory and time histories of kinematic and dynamic quantities show good agreement with the available experimental data and other CFD results, indicating the validity of the CFD-based modelling method for hull-propeller-rudder interaction of twin-screw ships.