Hydrodynamic characteristic investigations of a collaborative spoiled rudder under open water conditions

This study presents the hydrodynamic performance estimation of a collaborative spoiled rudder (CSR) - a new concept of ship rudder under open water conditions. The grid sensitivity study is carried out and the numerical method used in this work is validated by comparing with experimental data. The hydrodynamic performances of different CSR configurations at various rudder angles are simulated. The result shows that the existence of the spoiler has positive effect on the rudder lift and the effect gets more obvious with the increase of spoiler open angle. The spoiler can be controlled easily owing to the small spoiler stock torque. The optimal matching results show that, under the optimal matching conditions, the lift to drag ratios of the CSR are generally higher than those of the CR for the same target lift, and the improvement of the CSR in the rudder effectiveness gets more obvious with the increase of target lift. Furthermore, the CSR having the optimal matching rudder angle and spoiler open angle is much easier to steer compared with the CR with the same lift being generated. Overall, properly adjusting the rudder angle and the spoiler open angle of the CSR can significantly improve the rudder effectiveness. •The spoiler has positive effect on the lift and the effect gets more obvious with the increase of the spoiler open angle.•The lift to drag ratios of the CSR under the optimal matching conditions are significantly lager than those of the CR for the same target lifts.•The superiority of the CSR in terms of effectiveness is more dramatical under high lift condition.•The spoiler open torque can be ignored compared with the rudder stock torque of the CR.