Hard sail optimization and energy efficiency enhancement for sail-assisted vessel

The shipping industry has valued wind energy in the last decades due to the global increasingly severe environmental situation. The sail-assisted vessels have employed generous types of sails to exploit wind energy and reduce the energy consumption. To meet the ever-increasing energy saving requirements of sail-assisted vessels, this paper investigates the hard sail design optimization and energy efficiency enhancement problems for sail-assisted vessel. By using parametric section airfoil parametrization (PARSEC) method and particle swarm optimization algorithm, we fulfill the optimization of the wingsail aerodynamic design. The performance of our optimized airfoil has been verified by multi-point theory, computational fluid dynamics (CFD) examination, and energy efficiency design index (EEDI) calculation. The maximum lift-to-drag ratio of the coupled wingsails has increased by 10% than that of the arc-shaped sail. And the vessel equipped with our coupled wingsails can remarkably reduce EEDI by 18.2% and 4% when compared to non-sails vessel, and the vessel equipped with variable-camber sail (VCS), respectively.