Performance Improvement in a Wavy Twisted Rudder by Alignment of the Wave Peak

Abstract

An improved wavy twisted rudder (WTR) is proposed based on a previous study. The misalignment of the wavy and propeller centers and the computational work of the previous study are supplemented to determine the effectiveness of the developed wavy twisted rudder. The aligned wavy twisted rudder (AWTR) was also applied to a KRISO container ship (KCS). The resistance, self-propulsion performance, and rudder forces due to the angular variation in the WTR and AWTR were compared using computational fluid dynamics (CFD). The numerical results were compared with the experimental results. The self-propulsion performance of the AWTR was superior to that of the WTR, with an efficiency gain of approximately 0.3% in both the model test and numerical analyses. The effectiveness of the AWTR was demonstrated using CFD; the CFD improved for the WTR in comparison with a conventional twisted rudder, especially at large rudder angles. The stall point of the AWTR was approximately 5° greater than that of the WTR in both directions. The results confirm the superiority of the AWTR in terms of its delayed stall and high lift-to-drag ratio, which was investigated by visualizing the streamline around the rudder. The actual maneuverability, such as the turning circle, realized with AWTR shall be compared with that realized with a WTR and conventional TR in the near future.