METHOD OF OPTIMIZING DUCTED ANTI-TORQUE ROTOR OF ROTORCRAFT, IN PARTICULAR HELICOPTER, TO MINIMIZE ACOUSTIC ANNOYANCE, AND DUCTED ANTI-TORQUE ROTOR OBTAINED THEREBY

摘要

PROBLEM TO BE SOLVED: To provide a method of improving the aerodynamic performance of a ducted tail rotor anti-torque device with minimum acoustic annoyance for a rotorcraft. SOLUTION: In the method, the noise emitted from the ducted tail rotor anti-torque device with the frequency FE, and sensed with the frequency FP is minimized. In this method, the diameter D of the rotor, the number b of blades, and the tangential velocity U are determined so that the sensible frequency FP is equal to or less than the lower limit frequency FL of the predetermined 1/3 frequency octave around the frequency FC. COPYRIGHT: (C)2009,JPO&INPIT