| 主权项 |
1. An acoustic structure having multiple degrees of acoustic freedom for reducing noise generated from a source, said acoustic structure comprising:
A) a honeycomb comprising a first edge to be located closest to said source and a second edge, said honeycomb comprising a plurality of walls that extend between said first and second edges, said walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said walls; B) acoustic barriers located at the second edge of said honeycomb or within said cells to form acoustic resonators wherein the depth of each of said acoustic resonators is equal to the distance between the first edge of said honeycomb and said acoustic barrier; C) a first acoustic septum cap comprising:
a first anchor portion for anchoring said first acoustic septum cap to said walls at first anchoring depth within one of said cells, said first anchor portion having an outer edge that defines a perimeter of said first acoustic septum cap and a first interior anchor boundary that is spaced from said perimeter a first anchoring distance, said first anchor portion extending parallel to said walls and being bonded thereto with an adhesive that extends from said outer edge of the first anchor portion to said first interior anchor boundary, said first interior anchor boundary being located at said first anchoring depth;a first septum depth control portion which comprises an exterior boundary that coincides with said first interior anchor boundary and a first septum boundary wherein said first septum boundary is spaced from the exterior boundary of said first septum depth control portion a first depth control distance, said first septum depth control portion extending parallel to said walls;a first septum portion that is attached to said first septum boundary, said first septum portion extending transverse to said walls; and D) a second acoustic septum cap comprising:
a second anchor portion for anchoring said second acoustic septum cap to said walls at a second anchoring depth within another one of said cells, said second anchor portion having an outer edge that defines a perimeter of said second acoustic septum cap and a second interior anchor boundary that is spaced from said perimeter a second anchoring distance, said second anchor portion extending parallel to said walls and being bonded thereto with an adhesive that extends from said outer edge of the second anchor portion to said second interior anchor boundary, said second interior anchor boundary being located at said second anchoring depth;a second septum depth control portion which comprises an exterior boundary that coincides with said second interior anchor boundary and a second septum boundary wherein said second septum boundary is spaced from the exterior boundary of said second septum depth control portion a second depth control distance, said second septum depth control portion extending parallel to said walls and wherein said second depth control distance is different from said first depth control distance;a second septum portion that is attached to the second septum boundary, said first septum portion extending transverse to said walls, wherein the first anchoring depth to which said adhesive extends is equal to the second anchoring depth to which said adhesive extends and wherein said first septum portion and said second septum portion are located at different depths within said cells due to said second septum depth control distance being different from said first depth control distance to thereby provide said acoustic structure having multiple degrees of acoustic freedom. |
