THE METHOD FOR PREDICTING THE PERFORMANCE OF PROPELLER-RUDDER SYSTEM WITH RUDDER ANGLE AND ITS APPLICATION TO THE RUDDER DESIGN

In this paper the performance of the system of a propeller and a rudder with rudder angle behind a ship is treated hydrodynamically from the propulsion and manoeuvring viewpoint. The propeller and the rudder behind a ship are regarded as a unit to generate the thrust and the lateral force, which is named PRS (Propeller-Rudder- System). In order to calculate the performance characteristics of PRS, for simplicity, the simplified propeller theory is applied to calculate the forces acting on the propeller, assuming an infinitely bladed propeller. The panel method in the lifting body theory is adopted to calculate the forces acting on the rudder, taking into account the friction force obtained by two dimensional boundary layer calculation. The mutual interaction is taken into consideration by superposing the induced velocity by the other on the inflow. The contraction by the simple method is introduced for the free steam of the propeller as the inflow into the rudder. When a PRS is set in uniform flow, the performance characteristics of the PRS is calculated. The calculated results of the thrust and the lateral force acting on PRS show good agreement with the experimental results. The assessment of the performance characteristics of PRS is also discussed. Finally the proposed method to calculate the performance characteristics of PRS is applied to design rudders.