INTERACTION VELOCITY FIELD METHOD FOR PREDICTING SHIP RUDDER- PROPELLER INTERACTION

A theoretical method has been developed to predict the forces developed due to the interaction between a ship rudder and propeller. A parallel lifting surface panel program (PALISUPAN) has been written and this forms the basis of the technique. The rudder and propeller are modelled separately. Their interaction is accounted for through an iterative process thereby their respective inflow velocity fields are modified using a circumferential average of the disturbance velocity due to the other body. A perturbation potential formulation is used and a zero pressure loading condition enforced at the trailing edge. Modelling the interaction allows the influence of the propeller on rudder forces to be determined as well as the corresponding effect of the rudder on the propeller. A good prediction of rudder and propeller forces was obtained when the theoretical results were compared with results obtained from wind tunnel tests. The method allows the influence of both flow and geometrical parameters on rudder-propeller interaction to be investigated and hence should provide a valuable tool for the enhanced design of ship rudder-propeller systems.