Acoustic array of polymer material

1. A rotating machine, comprising:

a casing defining a cavity and having an impeller arranged for rotation within the cavity, the cavity being fluidly coupled to an inlet conduit and a diffuser channel;

a first acoustic liner mounted to a metal diffuser wall defined in the diffuser channel to attenuate noise, the first acoustic liner being annular and having a first plurality of cells tightly-coupled together to form a first cell matrix;

a second acoustic liner mounted to the metal diffuser wall opposite the first acoustic liner and adapted to attenuate noise, the second acoustic liner being annular and having a second plurality of cells tightly-coupled together to form a second cell matrix, and the first and second acoustic liners being at least partially non-metallic; and

a backing member disposed between the first and second acoustic liners and the respective metal diffuser walls, wherein

each cell of the first cell matrix and the second cell matrix is a single bore extending axially from the diffuser channel to the backing member,

each cell of the first cell matrix and the second cell matrix defines a flowpath having a uniform cross-section from the diffuser channel to the backing member, and

each cell of the first cell matrix and the second cell matrix has six or more sidewalls.

2. The rotating machine of claim 1 , wherein each of the plurality of cells is hexagonally-shaped such that the first cell matrix forms a honeycomb structure.

3. The rotating machine of claim 1 , wherein the first and second acoustic liners include one of a plastic, polymer, thermoplastic, or thermoset.

4. The rotating machine of claim 1 , wherein the first and second acoustic liners include polyetheretherketone.

5. The rotating machine of claim 1 , further comprising:

a third acoustic liner arranged axially-adjacent a front end of the impeller and disposed within a first excised portion of an internal cavity wall, the third acoustic liner being annular and having a third plurality of cells tightly-coupled together to form a third cell matrix; and

a fourth acoustic liner arranged axially-adjacent a rear end of the impeller and disposed within a second excised portion of the internal cavity wall, the fourth acoustic liner being annular and having a fourth plurality of cells tightly-coupled together to form a fourth cell matrix, wherein the third and fourth acoustic liners are at least partially non-metallic.

6. The rotating machine of claim 1 , further comprising:

a third acoustic liner arranged in the inlet conduit to attenuate noise, the third acoustic liner being cylindrical and having a third plurality of cells tightly-coupled together to form a third cell matrix, the third acoustic liner being at least partially non-metallic.

7. The rotating machine of claim 1 , further comprising:

a third acoustic liner mounted to the metal diffuser wall juxtaposed with the first acoustic liner, the third acoustic liner being annular and having a third plurality of cells tightly-coupled together to form a third cell matrix, the third acoustic liner being at least partially non-metallic.

8. The rotating machine of claim 7 , wherein the first plurality of cells are in fluid communication with the third plurality of cells, and the first plurality of cells are of a different size than the third plurality of cells.

9. The rotating machine of claim 1 , wherein a relative depth of each of the first plurality of cells varies.

10. The rotating machine of claim 9 , wherein the relative depth of each of the first plurality of cells at least one of progressively increases in a radial-outward direction and progressively decreases in a radial-outward direction.

11. An acoustic liner for noise attenuation in rotating machinery, the acoustic liner comprising a plurality of cells coupled together to form an annular cell matrix, the plurality of cells being made of a non-metallic material, wherein

each cell of the plurality of cells has two ends axially separated from each other, a backing member being coupled to one of the two axially separated ends on a same side of the annular cell matrix,

each cell of the plurality of cells is a single bore extending between the backing member and the other axial end,

each cell of the plurality of cells defines a flowpath having a uniform cross-section from the other axial end to the backing member, and

each cell of the plurality of cells has six or more sidewalls.

12. The acoustic liner of claim 11 , wherein each cell of the plurality of cells is hexagonally-shaped such that the annular cell matrix forms a honeycomb structure.

13. The acoustic liner of claim 11 , wherein the non-metallic material is a polymer.

14. The acoustic liner of claim 13 , wherein the non-metallic material is polyetheretherketone.

15. The acoustic liner of claim 11 , wherein a relative depth of each of the plurality of cells progressively increases or decreases in a radial-outward direction.

16. A method for attenuating noise in a rotating machine, comprising:

arranging a first acoustic liner in a metal diffuser wall of the rotating machine, the first acoustic liner being annular and having a first plurality of cells tightly-coupled together to form a first cell matrix;

arranging a second acoustic liner in the metal diffuser wall opposite the first acoustic liner, the second acoustic liner being annular and having a second plurality of cells tightly-coupled together to form a second cell matrix, and the first and second acoustic liners being at least partially non-metallic;

arranging a backing member between the first and second acoustic liners and the respective metal diffuser walls; and

dissipating noise emanating from a working fluid as the working fluid traverses the first acoustic liner and the second acoustic liner, wherein

each cell of the first cell matrix and the second cell matrix is a single bore extending axially from a diffuser channel of the rotating machine to the backing member,

each cell of the first cell matrix and the second cell matrix defines a flowpath having a uniform cross-section from the diffuser channel to the backing member, and

each cell of the first cell matrix and the second cell matrix has six or more sidewalls.

17. The method of claim 16 , further comprising:

arranging a third acoustic liner in an inlet conduit of the rotating machine, the third acoustic liner being cylindrical and having a third plurality of cells tightly-coupled together to form a third cell matrix, and the third acoustic liner being at least partially non-metallic; and

dissipating additional noise emanating from the working fluid as the working fluid traverses the third acoustic liner.

18. The method of claim 16 , further comprising:

arranging a third acoustic liner axially-adjacent a front end of the impeller and disposed within a first excised portion of an internal cavity wall;

arranging a fourth acoustic liner axially-adjacent a rear end of the impeller and disposed within a second excised portion of the internal cavity wall, the third and fourth acoustic liners each being annular and at least partially non-metallic; and

dissipating noise emanating from the working fluid as the working fluid traverses the third and fourth acoustic liners.