Noise Generated by Secondary and Auxiliary Aircraft Systems

摘要

A variety of noise-generating mechanisms contribute to the overall noise environment encountered within fixed- and rotary-wing aircraft. The report contains descriptions and illustrations of secondary and auxiliary systems found within aircraft which contribute to the composite noise. Types of noise-generating mechanisms include: (1) transmission, gear-reduction, and shaft distribution systems; (2) air-conditioning and pressurization systems; (3) defrosting systems; (4) air-distribution ducts and vents, and air- circulating and blower units; (5) ground and airborne auxiliary power units and systems; and (6) aerodynamic and aeroelastic disturbances, including devices such as air brakes and landing gear. (Author)