Non-conventional flat back thick airfoils for very large offshore wind turbines

Especially for very large wind turbines, flat back thick geometries are very interesting and attractive since they can provide very good structural properties to the blade without dramatically sacrifice the aerodynamic performance in terms of lift. In addition, they help to reduce transportation problems; in fact they are used at the root of the blade where the structural requirements are more demanding and where the maximum chord is located. The present work is focused on the design of thick flat back airfoils. In particular, a new solution is presented and discussed to improve the aerodynamic behavior of the thick sections without sacrifice their structural characteristics. It is known indeed that the flow over these geometries is highly unsteady and the drag is also relevant. The solution presented in the work aims to unsteadiness and drag reduction. A Numerical analysis has been performed by using CFX. According to the results, the new solution has potentialities to reduce significantly the drag and stabilize the flow.