Multi degree of freedom flutter damper

1. A flutter damper, comprising:

an acoustic liner in fluid communication with a fluid flow, the acoustic liner being configured for peak acoustical energy absorption at a frequency range that is greater than a frequency range associated with fan flutter; and

a plurality of modular chambers, each of the plurality of modular chambers being configured for peak acoustical energy absorption at a frequency range that is associated with one or more fan flutter modes; and

the plurality of modular chambers being disposed radially outside of the acoustic liner, and the plurality of modular chambers including a circumferential gap between proximate circumferential ends of at least one adjacent pair of modular chambers;

wherein, the plurality of modular chambers each include a plurality of circumferentially aligned and connected chamber segments;

each of the plurality of modular chambers has a volume and a mutually common shape; and

circumferential ends of the modular chambers are beveled.

2. The flutter damper of claim 1 , wherein circumferentially adjacent acoustic chamber segments in each of the modular chambers are acoustically insulated.

3. The flutter damper of claim 2 , wherein at least two of the plurality of modular chambers are configured for peak acoustical energy absorption at a frequency range that is associated with mutually distinct fan flutter modes.

4. The flutter damper of claim 3 , comprising a plurality of circumferential gaps respectively disposed between each pair of proximate circumferential ends of the modular chambers.

5. The flutter damper of claim 1 , including a cover sheet disposed on the acoustic perforated only in areas between the acoustic liner and the plurality of modular chambers.

6. The flutter damper of claim 5 , wherein the chamber segments are box or rectangular shaped.

7. The flutter damper of claim 5 , wherein the chamber segments are elliptical.

8. The flutter damper of claim 1 , wherein the modular chambers are a metallic material, including aluminum, or a plastic or a composite, or a hybrid metallic and non-metallic material.

9. A gas turbine engine comprising:

a nacelle;

an flutter damper disposed within the nacelle, the flutter damper including:

an acoustic liner in fluid communication with a fluid flow, the acoustic liner being configured for peak acoustical energy absorption at a frequency range that is greater than a frequency range associated with fan flutter; and

a plurality of modular chambers, each of the plurality of modular chambers being configured for peak acoustical energy absorption at a frequency range that is associated with one or more fan flutter modes; and

the plurality of modular chambers being disposed radially outside of the acoustic liner, and the plurality of modular chambers including a circumferential gap between proximate circumferential ends of at least one adjacent pair of modular chambers;

wherein, the plurality of modular chambers each include a plurality of circumferentially aligned and connected chamber segments;

each of the plurality of modular chambers has a volume and a mutually common shape; and

wherein circumferential ends of the chambers are beveled.

10. The gas turbine engine of claim 9 , wherein circumferentially adjacent chamber segments in each of the modular chambers are acoustically insulated.

11. The gas turbine engine of claim 10 , wherein at least two of the plurality of modular chambers are configured for peak acoustical energy absorption at a frequency range that is associated with mutually distinct fan flutter modes.

12. The gas turbine engine of claim 11 , comprising a plurality of circumferential gaps respectively disposed between each pair of proximate circumferential ends of the modular chambers.

13. The gas turbine engine of claim 9 , including a cover sheet disposed on the acoustic perforated only in areas between the acoustic liner and the plurality of modular chambers.

14. The gas turbine engine of claim 13 , wherein the chamber segments are box or rectangular shaped.

15. The gas turbine engine of claim 13 , wherein the chamber segments are elliptical.

16. The gas turbine engine of claim 9 , wherein the modular chambers are a metallic material, including aluminum, or a plastic or a composite, or a hybrid metallic and non-metallic material.

17. A method of providing flutter damping in a gas turbine engine, comprising: absorbing acoustic energy with an acoustic liner configured for peak acoustical energy absorption at a frequency range that is greater than a frequency range associated with fan flutter; and absorbing acoustic energy with a plurality of modular chambers, each of the plurality of modular chambers being configured for peak acoustical energy absorption at a frequency range that is associated with one or more fan flutter modes; wherein the plurality of modular chambers are disposed radially outside of the acoustic liner and separated by a circumferential gap between proximate circumferential ends of at least one adjacent pair of modular chambers, and wherein the plurality of modular chambers each including a plurality of circumferentially aligned and connected chamber segments each of the plurality of modular chambers has a same volume and a mutually common shape; and circumferential ends of the modular chambers are beveled.

18. The method of claim 17 , wherein the chamber segments have the same volume and mutually common length, width and/or height, or shape.

19. The method of claim 17 , wherein circumferentially adjacent chamber segments in the modular chambers are acoustically insulated from each other.

20. The method of claim 19 , wherein at least two of the plurality of modular chambers are configured for peak acoustical energy absorption at a frequency range that is associated with mutually distinct fan flutter modes.

21. The method of claim 20 , comprising a plurality of circumferential gaps respectively disposed between each pair of proximate circumferential ends of the modular chambers.