Simultaneous Vibration Reduction and Performance Enhancement in Rotorcraft Using Actively Controlled Flaps

Abstract A computational study of helicopter vibration and rotor shaft power reduction is conducted using activelycontrolled trailing-edge flaps (acfs), implemented in single and dual flap configurations. Simultaneous vibration reduction and performance enhancement is demonstrated under level flight condition at high advance ratios, where dynamic stall effects are significant. Power reduction is achieved using the adaptive Higher Harmonic Control (hhc) algorithm in closed loop, with 2-5/rev flap control harmonics. This approach is compared with an off-line, nonlinear optimizer lsqnonlin available in the matlab package, and favorable comparisons are obtained. Subsequently a parametric study of flap spanwise location is conducted to determine the optimal flap location for power reduction. Finally the effectiveness of acf approach for power reduction is compared with that of the conventional individual blade control (ibc) approach. The simulation results clearly demonstrate the potential of the acf system for power reduction as well as simultaneous vibration and power reduction. Nomenclature c Blade chord c c Flap chord Yawing moment about rotor hub N b Number of rotor blades P R Rotor shaft power R Rotor blade radius Q Weighting matrix for objectives to be reduced R Weighting matrix on control inpu