Bypass duct fan noise reduction assembly

Abstract

A gas turbine engine fan assembly includes fan blades spaced axially from stator vanes inside an annular bypass duct. A plurality of perforated baffle plates are installed in the annular bypass duct downstream of the stator vanes. The perforated baffle plates extend in a generally axial direction and are unevenly, circumferentially spaced apart from one another to divide a major section of the annular bypass duct into a plurality of axial flow-path segments in an asymmetrical pattern to disrupt continuity, destroy a symmetrical pattern and absorb sound energy of a spinning mode of sound pressures imbedded in the air flow downstream of the stator vanes, without substantially affecting a thrust provided by the air flow when discharged from the bypass duct. The invention provides a solution for suppressing rearward noise propagation of a fan BPF tone and higher harmonics thereof through the annular bypass duct of a gas turbine engine, which contributes to the reduction of aircraft noises, particularly during take-off.

Dependencies are inferred from the claim text.