Robust aerodynamic optimization strategies for rotor blade morphing airfoils

Abstract

An aerodynamic optimization method is developed to define robust shapes for morphing airfoils for helicopter blades. The morphing strategy consists of a conformable camber airfoil which changes over the period of rotation of the blade to cope with the variable ow conditions encountered in forward flight. A robust or uncertainty-based approach is used to compute a reliable morphing airfoil, providing a low variance with respect to uncertainty affecting the operating conditions. In order to assess the effectiveness of the robust method, several optimization problems are performed, from a classical two-point drag minimization with lift coefficient constraint to a robust morphing camber optimization. The results of the optimization problems are compared and discussed to highlight the features of the robust approach.