Non-harmonic deployment of active devices for rotor performance enhancement

A computational method is introduced which generates a non-harmonic deployment schedule for an active device that is optimized to reduce the total power required of a rotor over a designated flight envelope. A trailing edge flap is added to the UH-60A's rotor and the flap's span, deflection magnitudes, and deployment azimuth positions are all optimized to minimize the total power of the rotor over a flight envelop of μ=0.05 to μ=0.37. The formal optimization effort is carried out through the coupling of a comprehensive analysis code, RCAS, and an evolutionary algorithm based optimizer CMA-ES. A peak power savings of 15.23%, at μ=.30, is found from a twist optimization study which provides an achievable power savings limit for the active device study. With a trailing edge flap, an optimized deployment schedule is found at each advance ratio over an entire flight envelope which minimizes total power of the rotor, including a peak power savings of 9.51% at μ=.30. The resulting effects of the non-harmonic trailing edge deployments on the rotors hub vibratory and pitch-link loads are also analyzed.