Aerodynamic design of ‘box blade’ and ‘non-planar’ wind turbines

Abstract

In this paper the aerodynamic efficiency of wind turbines with horizontal axis is discussed and the so-called box blade concept, inspired by the Prandtl’s ‘Best Wing System’ is analysed; this wind turbine configuration is proved to be efficient than a conventional blade. Moreover, other non-planar blades, such as the winglet and C extension are analysed via vortex theorywith the numerical method of Ribner and Foster for the optimum circulation and the recent model of Okulov and Sørensen for the performance evaluation; a generalization of the above mentioned models is also presented in this work. Finally, the box blades are verified by means of a commercial CFD software.