Design and optimization of airfoil profiles for vertical wind turbines

Abstract

Offshore floating vertical axis wind turbines could be a great renewable energy source to meet the needs for renewable energy since they can be placed in deep waters and unlock new potential areas for wind farms. The specific operating conditions of a vertical axis wind turbine blade call for a purposely designed airfoil profile to improve performance and reduce cost. The blades must be both aerodynamically and structurally good. Airfoil profiles were optimized using a genetic algorithm with both an aerodynamic and structural objective: to maximize the power coefficient and to maximize the section modulus. The power coefficient was calculated with the actuator cylinder method using polars from XFoil which captured the operating conditions of the vertical axis wind turbine. The obtained optimized family of airfoils showed increased blade and turbine performance compared to the often used NACA 0018. Some of the optimized airfoil profile have the potential to reduce the weight of vertical axis wind blades based on a simple estimation.