Real-time rotational speed control and EEDI reduction research of rotor sail via high-Re aerodynamics and power Rose graph

Installing rotor sail on ship can effectively utilize wind energy to assist navigation, and is an important technical means to achieve energy conservation and emission reduction in the shipping industry. However, in complex sea conditions, how to adjust the speed in real time to improve the propulsion performance of the sail is still an urgent problem to be solved. This article is based on the two-dimensional unsteady N-S equation, and establishes an aerodynamic performance analysis model for rotor sail under high Reynolds number conditions. The multi parameter coupling effects of different ship speeds (10 ~ 22 kn), rotational speeds (60 ~ 540 rpm), wind speeds (1 ~ 20 m/s), and wind direction angles (0 ~ 360°) are systematically studied. The results indicate that the aerodynamic performance of the rotor sail exhibits significant nonlinear characteristics, and the optimal critical rotational speed for aerodynamic performance varies under different operating conditions. Based on numerical simulation results, an innovative effective power rose graph was constructed, and a dynamic control strategy for the rotational speed of the rotor sail was proposed to achieve real-time matching of ship speed, wind speed, and wind direction. Finally, taking a 15000t bulk carrier as an example, the energy-saving effect of the rotor sail was quantitatively evaluated. The results showed that after installing a unit height (1 m) rotor sail, the reduction of Energy Efficiency Design Index (EEDI) value of the ship is 0.7%. This study provides a reference theoretical basis and preliminary optimization method for the practical application of rotor sail (under steady-state, 2D simplifications) on ship through high-precision numerical simulation and engineering verification, which has important practical significance for the development of green shipping technology.