Optimization design and experimental verification of unmanned sailboat sails

With the increasing demand for ocean resource development and environmental monitoring, wind-powered unmanned sailboats have gained significant attention as autonomous equipment capable of long-duration and long-distance operations at sea. In the present study, the aerodynamic performance of wing sails for the “FanHai-T1” unmanned sailboat is evaluated from different airfoil types, aspect ratios, and angles of attack based on computational fluid dynamics simulation. The optimal airfoil type, chord length, and aspect ratio are confirmed to ensure sufficient thrust for sailboat navigation. Considering that the wing sail must meet certain stiffness and strength requirements to withstand harsh sea conditions, the topology optimization of the wing sail's internal structure is conducted through a variable-density method based on solid isotropic material with penalization interpolation. The internal material distribution density of the wing sail is set as the design variable. The material volume fraction, sail strength, and maximum allowable deformation are defined as constraints. The maximum stiffness is determined as the objective function. Finally, water tank tests are carried out to verify the seaworthiness of the FanHai-T1 unmanned sailboat equipped with the optimized wing sail. The optimized sail is proven to not only demonstrate excellent aerodynamic performance but also satisfy requirements for structural stiffness, strength, and lightweight design.