A Study on Twisted Rudders on Medium-Sized Transport Ships Based on Experiments and CFD

To enhance the energy efficiency of medium-sized transport vessels, one set of conventional flat rudders and three sets of twisted rudders with different twist angles were designed for a single-propeller single-rudder medium-sized transport ship. By combining model tests and computational fluid dynamics (CFD) numerical simulations, this paper systematically investigates the influence of twist angle on ship propulsion performance and energy-saving effects and reveals the corresponding energy-saving mechanism. The results show that compared with the conventional flat rudder, all three sets of twisted rudders achieve energy savings, with the main engine power reduced by approximately 1.0%. Within the research scope of this paper, the energy-saving effect improves with the increase in twist angle. Compared with the flat rudder, the installation of a twisted rudder leads to reductions in propeller thrust, torque, and rudder resistance, while the propeller’s rotational speed remains essentially unchanged. The CFD calculation results are in good agreement with the experimental data, which accurately reflect the flow field differences and explain the energy-saving mechanism. Thus, CFD can be used as an effective method for the design and optimization of twisted rudders.