To accurately evaluate the energy-saving performance of a pre-swirl duct (PSD) and reveal its underlying mechanisms, this study takes an 8,800 TEU container ship as the research subject. Numerical simulations of ship model resistance, propeller open-water performance, and self-propulsion performance were performed using the Reynolds-averaged Navier-Stokes (RANS) method. The numerical method was validated against towing tank test results. Based on this, the primary energy-saving mechanisms were systematically revealed by analyzing the effects of the PSD on the wake field, propeller performance, and wake kinetic energy. At the design speed, the predicted energy-saving rates are 2.78% (CFD) and 2.74% (EFD). Under off-design conditions, the average rates are 2.86% (CFD) and 2.72% (EFD), showing good agreement between predictions and experiments. The PSD generates a pre-swirl flow via its guide fins, which optimizes the propeller inflow, improves blade performance, and suppresses transverse flow in the wake. The accurate numerical method and the systematic analysis of energy-saving mechanisms presented in this study provide a foundation for future optimization of PSDs.

Aiming at the energy conservation and emission reduction of the ship, a marine solar photovoltaic flexible support which can be laid on the deck has been designed based on the parameters and operation conditions of the KVLCC2, and the vibration response characteristics are analyzed. The effects of the wind load and the pitch and heave of the ship on the vibration response characteristics of the flexible support are studied by using the fluid-structure interaction decoupling calculation method. The results show that the amplitude and the average internal stress of the steel cable are the largest under the pitch condition, which have an adverse effect on the flexible support, followed by the pitch and heave conditions, and the lowest under the heave condition. The maximum structural stress occurs at the boundary of the steel cable support, and the plastic deformation will occur earliest if the external load increases further. The average stress and amplitude of the steel cable in the middle of the flexible support are the largest, and fatigue failure may occur under the cyclic stress and strain. The above conclusions provide a basis for the design, manufacture and daily use of the marine solar photovoltaic flexible support.