ACTIVE CONTROL OF PROPELLER-INDUCED NOISE FIELDS INSIDE A FLEXIBLE CYLINDER

An active noise control model for reducing aircraft interior noise has been evaluated. The structural noise transmission properties of an aircraft fuselage were modeled as a flexible cylinder excited by external acoustic dipoles simulating the noise produced by twin propellers. The amplitudes of an internal distribution of monopole control sources were determined such that the area-weighted, mean-square acoustic pressure was minimized in the propeller plane. The noise control model was evaluated at low frequencies corresponding to the blade passage frequency and the first few harmonics of a typical turboprop aircraft. Interior noise reductions up to 20 dB were achieved over a substantial region of the cylindrical cross section, with just a few monopole control sources. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.