Acoustic liner and methods of constructing an acoustic liner

1. An acoustic liner, comprising:

a support layer that includes a set of partitioned cavities with open faces;

a facing sheet operably coupled to the support layer such that the facing sheet overlies and closes the open faces, a surface of the facing sheet includes at least one of a partial perforation, a recess, and a channel, each of which extends less than all the way through the facing sheet; and

a set of perforations included in the facing sheet, and in fluid communication with cavities included in the set of cavities to form a set of acoustic resonators and where the set of perforations are formed via grit blasting and range in diameter from 0.026 inches to 0.0299 inches, each of the set of perforations being arranged on the facing sheet separately from the at least one partial perforation, recess, and channel.

2. The acoustic liner of claim 1 , further comprising an imperforate backing sheet supported on a side of the support layer opposite the facing sheet.

3. The acoustic liner of claim 1 wherein the facing sheet is a composite facing sheet.

4. The acoustic liner of claim 1 wherein at least one perforation includes an inlet and an outlet where the inlet has a larger diameter than the diameter of the outlet.

5. A method of constructing an acoustic liner, the method comprising:

applying a mask with openings onto a facing sheet;

forming perforations, ranging in diameter from 0.026 inches to 0.0299 inches, and at least one of a partial perforation, a recess, and a channel, each of which extends less than all the way through the facing sheet, in a surface of the facing sheet by grit blasting the facing sheet and the mask applied to the facing sheet such that the mask blocks the grit and the openings in the mask permit the grit to contact the facing sheet and form the perforations and the at least one of the partial perforation, the recess, and the channel, each of the perforations being arranged on the facing sheet separately from the at least one partial perforation, recess, and channel; and

mounting the facing sheet to a first side of a support layer having a set of partitioned cavities and where the facing sheet closes an open face of the cavities except for the perforations to form a set of acoustic resonator cells.

6. The method of claim 5 wherein the facing sheet is grit blasted prior to mounting the facing sheet to the one side of the support layer.

7. The method of claim 5 wherein the facing sheet is grit blasted after mounting the facing sheet to the one side of the support layer.

8. The method of claim 5 wherein the grit blasting the facing sheet includes grit blasting a composite sheet.

9. The method of claim 8 wherein the composite sheet includes a resin and fiber construction.

10. The method of claim 5 , further comprising applying a mask with openings onto the facing sheet, with the mask blocking the grit and the openings permitting the grit to contact the facing sheet and form the perforations at the openings.

11. The method of claim 5 wherein the mask is applied to a front side of the facing sheet.

12. The method of claim 1 wherein the grit blasting forms a perforation having an inlet and an outlet and the diameter of the inlet is larger than the diameter of the outlet.

13. The method of claim 1 wherein applying the mask comprises applying a mask having multiple layers.

14. The acoustic liner of claim 1 , wherein at least one cavity in the set of cavities is in fluid communication with only one perforation in the set of perforations to form an acoustic resonator in the set of acoustic resonators.

15. The acoustic liner of claim 1 , wherein

each of the perforations in the set of perforations extends all the way through the facing sheet.

16. The acoustic liner of claim 1 , wherein the facing sheet is provided within a nacelle of an aircraft engine, without an intervening linear liner between the facing sheet and a turbine of the aircraft engine.

17. The acoustic liner of claim 1 , wherein the facing sheet is coupled to the support layer on a side of the support layer that is closest to a turbine of an aircraft engine.

18. The acoustic liner of claim 1 , wherein the surface of the facing sheet is a side of the facing sheet closest to a turbine of an aircraft engine.