Nacelle core with insert
Aspects of the disclosure are directed to a structure comprising: a plurality of cells, a first non-permeable insert in a first cell of the plurality of cells, the first insert configured to constrict, by at least a first threshold amount, a flow of fluid in the first cell such that: acoustic power over a frequency range is attenuated by the structure by at least a second threshold amount, and a resonant frequency associated with the structure is shifted by at least a third threshold amount.
1. A structure comprising:
a plurality of cells;
a non-permeable first insert in a first cell of the plurality of cells, the first insert configured to constrict, by at least a first threshold amount, a flow of fluid in the first cell such that:
acoustic power over a frequency range is attenuated by the structure by at least a second threshold amount, and
a resonant frequency associated with the structure is shifted by at least a third threshold amount;
wherein a surface of the first insert forms a hole that extends along an axis through the first insert, and a sectional geometry of the surface as viewed in a plane parallel to the axis is substantially round.
2. The structure of claim 1 , wherein the first threshold amount is 90%.
3. The structure of claim 1 , wherein the frequency range corresponds to 0-10 KHz.
4. The structure of claim 1 , further comprising a non-permeable second insert, wherein the first insert is located at a first distance as measured from a bottom of the first cell, and wherein the second insert is located at a second distance as measured from the bottom of the first cell.
5. The structure of claim 4 , wherein the first distance and the second distance are different.
6. The structure of claim 1 , further comprising a non-permeable second insert, wherein the second insert is located in the first cell.
7. The structure of claim 1 , further comprising a non-permeable second insert, wherein the second insert is located in a second cell of the plurality of cells.
8. The structure of claim 1 , wherein each of the plurality of cells has a substantially hexagonal shape, and wherein the cells are arranged relative to one another to form a honeycomb profile.
9. The structure of claim 8 , wherein outer edges of the first insert adhere to the shape of the first cell.
10. The structure of claim 1 , wherein the frequency range and the second threshold amount are based on at least one of:
a count of inserts within at least one of the cells,
a location of the first insert within the first cell,
a size of the first insert,
a size of a hole defined by the first insert,
a shape of the first insert, or
a shape of the first cell.
11. The structure of claim 1 , wherein the structure is configured to be incorporated in a nacelle of an aircraft.
12. The structure of claim 11 , wherein the structure is configured to be incorporated in at least one of a translating sleeve or a blocker door.
13. The structure of claim 11 , wherein at least one of the frequency range or the second threshold amount is based on a size of a fan housed within the nacelle.
14. The structure of claim 1 , wherein the frequency range corresponds to 0-1 KHz.
15. The structure of claim 1 , wherein the sectional geometry of the surface as viewed in the plane parallel to the axis is semi-circular.
16. A structure comprising:
a plurality of cells;
a non-permeable first insert in a first cell of the plurality of cells, the first insert configured to constrict, by at least a first threshold amount, a flow of fluid in the first cell such that:
acoustic power over a frequency range is attenuated by the structure b at least a second threshold amount, and
a resonant frequency associated with the structure is shifted by at least a third threshold amount;
a non-permeable second insert in a second cell of the plurality of cells; and
a non-permeable third insert in the second cell of the plurality of cells;
wherein the first insert is substantially located at a center of the first cell, the second insert is substantially located at a top of the second cell, and the third insert is substantially located at a bottom of the second cell.
17. The structure of claim 16 , wherein the first insert is a first distance from a bottom of the first cell, the second insert is a second distance from the bottom of the second cell, the third insert is a third distance from the bottom of the second cell, and the first distance is less than the second distance and greater than the third distance.
18. A structure, comprising:
a plurality of cells comprising a first cell; and
a non-permeable first insert arranged in the first cell, the first insert configured to constrict, by at least a first threshold amount, a flow of fluid in the first cell such that:
acoustic power over a frequency range is attenuated by the structure by at least a second threshold amount, and
a resonant frequency associated with the structure is shifted by at least a third threshold amount;
wherein an aperture extends along a centerline through the first insert, the aperture is partially formed by an annular edge portion of the first insert, and the annular edge portion comprises a curved bevel.
19. The structure of claim 18 , wherein the aperture is further partially formed by a second annular edge portion of the first insert, and the second annular edge portion comprises a curved bevel.