Numerical analysis of the effects of stern flaps on ship resistance and propulsion performance

Abstract

When a stern flap is installed on a high-speed surface ship, its role is often to reduce the ship resistance. However, the performance of a stern flap determined based on direct conversion of ship model resistance test results often has a large error. In this study, the ship model and stern flap coupling resistance tests and self-propulsion tests with integrated coupling of a ship-propeller-rudder-stern flap were performed based on the Reynolds-averaged Navier–Stokes method. The hull and propeller motions were based on overlapping grid and sliding mesh technology. The results show that while a stern flap reduces the ship resistance, it also affects the ship model flow field to a certain extent, consequently affecting the propulsion performance of the ship. The improvement in ship propulsion performance is one of the main factors contributing to the energy savings achieved by installing a stern flap, with a contribution between 30% and 50%. The integrated ship-propeller-rudder-stern flap calculation method is significantly improved compared with traditional ship model resistance tests as a means of determining the stern flap performances of full-scale ships.