Acoustic structure with increased bandwidth suppression

摘要

The bandwidth or acoustical range of a nacelle or other type of acoustic structure is increased by acoustically coupling honeycomb cells together to form pairs of acoustic cells that have an effective acoustic or resonator length that is up to twice that of either acoustic cell taken alone.

主权项

1. An acoustic structure for reducing noise generated from a source, said acoustic structure comprising:
a honeycomb comprising a first edge located closest to said source and a second edge, said honeycomb comprising a first acoustic cell defined by a plurality of walls that extend between said first and second edges and a second acoustic cell defined by a plurality of walls that also extend between said first and second edges of said honeycomb wherein said first acoustic cell and said second acoustic cell share a common wall; a first acoustic barrier for said first acoustic cell; a second acoustic barrier for said second acoustic cell; a surface in said common wall that defines an acoustic pathway between said first acoustic cell and said second acoustic cell, wherein said acoustic pathway is located between the first edge of said honeycomb and said first and second acoustic barriers; and a third acoustic barrier for said second acoustic cell wherein said acoustic pathway is located between the second acoustic barrier and said third acoustic barrier to thereby provide a first noise attenuation zone comprising the portion of said first acoustic cell located between said first edge and said first acoustic barrier and the portion of said second acoustic cell located between said second acoustic harrier and said third acoustic harrier, wherein said third acoustic harrier is displaced away from the first edge of said honeycomb such that said third acoustic barrier and the portion of said second acoustic cell located between said third acoustic barrier and said first edge form a second noise attenuation zone.