New Strategy for Design of Composite Rotor Blades with Active Flaps

This paper presents the development of a mixed variable optimization framework for the design of composite rotor blades with active flap in order to maximize the control authority for vibration reduction. For the studies presented in this paper, the amplitude of dynamic twist at the blade tip at 4/rev flap actuation frequency is used as the objective function and it is shown that there is a direct correlation between the amplitude of dynamic twist and the vibration reduction authority of active flaps. The optimization framework developed includes IXGEN as the cross section and mesh generator, UM/VABS for the cross-sectional analysis, and RCAS for the aeroelastic analysis of active rotor blades. The optimization problem is solved using a surrogate-based approach in combination with the Efficient Global Optimization (EGO) algorithm. The optimum results with both mixed and continuous design variables are obtained for three different spanwise locations of active flap.