CFD Investigation of Multi-element Airfoils for WingSails

Sammanfattning

Wind-assisted ship propulsion has gained increasing attention as a means of reducing fuel consumption and emissions in the maritime sector. This thesis studies the aerodynamic performance of an adjustable rigid wingsail designed to provide auxiliary thrust for ships. The wingsail consists of a NACA 0018-based main airfoil with a movable flap, where the flap deflection, hinge position, and gap between the main airfoil and flap can be varied. Computational Fluid Dynamics (CFD) simulations had been performed in OpenFOAM using the SST k–ω turbulence model to evaluate how these design parameters influence aerodynamic behaviour and propulsion performance. The results showed that increasing flap deflection enhanced lift generation by increasing the effective camber of the airfoil, although this was generally accompanied by increased drag. The hinge position influenced the aerodynamic response by altering the effective flap length, while the investigated gap configurations increased drag and did not improve overall aerodynamic efficiency compared with the plain-airfoil baseline. Analysis of wingsail orientation demonstrated that maximum lift does not necessarily correspond to maximum propulsive benefit, as both lift and drag contribute to thrust depending on the apparent wind direction and sail orientation. By resolving the aerodynamic forces into thrust and side-force components, operating conditions that provide favourable propulsive performance were identified. The outcomes contribute to the understanding and optimisation of adjustable rigid wingsails for wind-assisted ship propulsion.