Efficient active rotor concepts for in-plane noise reduction

Active rotor concepts have been shown to effectively target helicopter acoustics, performance, or vibrations. This work focuses on a conceptual integrated optimization scheme in which the Rotorcraft Comprehensive Analysis System (RCAS) is coupled to PSU-WOPWOP and an evolutionary algorithm to find trailing-edge flap deployment schedules that result in far-field in-plane noise reduction with the end goal of no performance penalty. A single-objective optimization is presented which demonstrates a 3.66 dB reduction in overall sound pressure level (OASPL) at a far-field observer with a performance penalty, as defined as an increase in rotor power required, of 10 percent. A multi-objective optimization is then presented that targets both OASPL and performance. A range of optimal deployment schedules are shown to result a 1-2 dB reduction in OASPL with a simultaneous power reduction of 4-6 percent.