Acoustic liners for use in a turbine engine
An acoustic liner for a turbine engine, the acoustic liner includes 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 set of perforations located in the facing sheet and in fluid communication with a corresponding one of the cavities to form a set of acoustic resonators, and at least a subset of the perforations have an axially-oriented, relative to the axial flow path, inlet.
1. An acoustic liner, comprising:
a support layer that includes a set of partitioned cavities with open faces;
a facing sheet having a first surface that is directly supported on the support layer such that the facing sheet overlies and closes the open faces;
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, wherein the acoustic liner is utilized in a turbine engine defining a through air flow having an axial flow path and at least a subset of the set of perforations have an axially-oriented inlet relative to the axial flow path, and each of the perforations in the set of perforations extends completely through the facing sheet from the first surface to a second surface of the facing sheet that faces away from the support layer; and
at least one discontinuity in the facing sheet upstream of the axially-oriented inlet.
2. The acoustic liner of claim 1 , wherein a perforation in the set of perforations includes an angled edge that is not normal to the first surface of the facing sheet.
3. The acoustic liner of claim 1 wherein the axially-oriented inlet has an elongated cross section in the axial flow path direction.
4. The acoustic liner of claim 3 wherein a shape of the axially-oriented inlet includes a teardrop.
5. The acoustic liner of claim 1 wherein the axially-oriented inlet includes a NACA scoop shaped inlet.
6. The acoustic liner of claim 1 wherein the at least a subset of the set of perforations includes an outlet in fluid communication with the corresponding one of the cavities and a conduit extending between the axially-oriented inlet and the outlet.
7. The acoustic liner of claim 6 wherein the axially-oriented inlet and the conduit have the same cross section.
8. The acoustic liner of claim 6 wherein the axially-oriented inlet extends from an upper surface of the facing sheet into a portion below the upper surface of the facing sheet.
9. The acoustic liner of claim 1 wherein the at least one discontinuity includes at least one riblet.
10. The acoustic liner of claim 9 wherein the at least one riblet includes a recess in the second surface of the facing sheet that extends less than completely through the facing sheet from the second surface of the facing sheet to the first surface of the facing sheet.
11. The acoustic liner of claim 1 , further comprising an imperforate backing sheet supported on a side of the support layer opposite the facing sheet.
12. An acoustic liner for a turbine engine, 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 a first surface of the facing sheet directly overlies and closes the open faces;
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, wherein at least a subset of the set of perforations have an axially-oriented inlet, relative to an axial flow path defined by the turbine engine, having an elongated cross section in the axial flow path direction, and each of the perforations in the set of perforations extends completely through the facing sheet from the first surface to a second surface of the facing sheet that faces away from the support layer; and
at least one discontinuity in the facing sheets upstream of the axially-oriented inlet.
13. The acoustic liner of claim 12 wherein a shape of the axially-oriented inlet includes a teardrop.
14. The acoustic liner of claim 13 wherein the at least a subset of the set of perforations includes an outlet in fluid communication with the corresponding one of the cavities of the set of partitioned cavities and a conduit extending between the inlet and the outlet.
15. The acoustic liner of claim 14 wherein the axially-oriented inlet extends from an upper surface of the facing sheet and into a portion of the facing sheet below an upper surface of the facing sheet.
16. The acoustic liner of claim 14 wherein the axially-oriented inlet and the conduit have the same cross section.
17. The acoustic liner of claim 12 wherein the at least one discontinuity includes at least one riblet.
18. An acoustic liner for a turbine engine, the 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 a first surface of the facing sheet directly overlies and closes the open faces;
a set of perforations located in the facing sheet and in fluid communication with a corresponding one of the cavities of the set of partitioned cavities to form a set of acoustic resonators; and
wherein the turbine engine defines a through air flow having an axial flow path and at least a subset of the set of perforations have an axially-oriented inlet, relative to the axial flow path, having an elongated cross section in the axial flow path direction, with the axially-oriented inlet generating less frictional drag than a circular inlet of the same cross-sectional area, and each of the perforations in the set of perforations extends completely through the facing sheet from the first surface to a second surface of the facing sheet that faces away from the support layer, and
the acoustic liner further comprising at least one discontinuously in the facing sheet upstream of the axially-oriented inlet.
19. The acoustic liner of claim 18 wherein a shape of the axially-oriented inlet includes a teardrop.