Propulsive performance of a novel crescent-shaped wind sail analyzed with unsteady RANS

Paper i proceeding, 2022

The use of wind-assisted ship propulsion is regarded as one of the effective ways to reduce greenhouse gas emissions. This study presents a numerical analysis of the aerodynamics of a single rigid wind sail using URANS (Unsteady Reynolds- Averaged Navier-Stokes equations). A new foil profile, the crescent-shaped foil, is proposed and then, compared with the classical profile NACA 0015. Both 2D and 3D simulations are conducted. The key physical quantities of interest are detailly discussed, such as the external loads on the sail, the induced flow field, as well as the propulsive performance. It is concluded that the wind sail with the crescent-shaped section has higher propulsion efficiency than that with NACA0015. However, flow separation is found for the former section. As the separation deteriorates the flow unsteadiness, this effect poses a challenge to the strength and stability of the wind sail structure. Moreover, the 3D simulations of both profiles, especially NACA 0015, show that the tip vortices induced from the sail side edge account for significant negative impacts on the propulsion performance.