A New Type of Collapsible Wing Sail and its Aerodynamic Performance

Abstract

In recent years, research on energy saving and emission reduction has been given much attention and the rise in the usage of renewable energy technologies has been remarkable. Through the use of wind energy, the goals of energy saving and emission reduction could be realized for ocean-going ships. Sail assisted technology is undoubtedly safe and reliable, but also is suitable for the current ship transportation. In order to ensure the safety of the ship and promote the full usage of clean energy at sea, a new type of ship propulsion-assisted wing sail was proposed innovatively. Focusing on the automatic and flexible structural features of the wing sail, this new type of collapsible wing sail is designed to increase the propulsion efficiency by enlarging the wing sail area in the transverse and vertical directions when the wind conditions get available. In the meanwhile, it can be folded up automatically in the poor weather condition and reduce the wind area in the transverse section and improve the sailing safety for ship. This new wing sail is composed of three parts: the main wing, the front wing and the back wing. Based on the technology of Computational Fluid Dynamics (CFD), the sail parameters such as gaps and rotation angles between different wings were investigated and the best setup parameters with excellent aerodynamic performance were fixed. Through the numerical simulation methods, the results of lift coefficients and drag coefficients for the new wing sail under different attack angles were obtained and also compared with the traditional arc-shaped rigid sail and variable-camber sail which was innovatively proposed by Qiao Li in 2015. From the viewpoint of the sailing performance of the vessel, our results demonstrate that this new type of wing sail has good aerodynamic performance and can reduce fuel costs for commercial vessels.