ECN-G1-21 Airfoil: Design and Wind-Tunnel Testing

The performance of the airfoils installed along the blades has a direct impact on the wind turbine performance. New airfoils tailored on specific requirements can help to obtain outstanding performance while reducing loads and mass. Especially for very large 8–10 MW turbines, where the blade length is in 100 m range, reducing the loads and tower top mass is a very attractive option to reduce the cost of energy and has not only feasible but also cost-effective products. This work focuses on the development of a new family of airfoils. The design strategy is based on numerical optimization coupled with the RFOIL solver. The numerical results show good potentialities in performance and consistent geometrical properties along the family. The 21% thick geometry has been wind-tunnel tested to validate the predictions. The tests have been carried out in free and fixed transitions at different Reynolds numbers. Special tests also include vortex generators. Although there is a general good agreement with the numerical predictions, the stall appears to still be a critical area. Based on these findings, a new 21% thick airfoil has been designed while also considering the stall behavior during the development.