Multi-plane brush seal

1. A multi-plane annular brush seal extending circumferentially about an axial centerline, the brush seal comprising:

a front plate;

a back plate having a BP base end, a first BP inner side surface, a BP inner side transition surface, a second BP inner side surface, and a BP tip end, wherein the first BP inner side surface extends from the BP base end to the BP inner side transition surface, and the second BP inner surface extends from the BP inner side transition surface to the BP tip end; and

a plurality of bristles attached to the front plate and the back plate at a base end of the brush seal, wherein each bristle has a first lengthwise portion extending from the base end, a second lengthwise portion, and a third lengthwise portion, and the second lengthwise portion of each respective bristle is disposed between the first lengthwise portion and third lengthwise portion of the respective bristle, and each third lengthwise portion terminates in a tip end;

wherein at any given circumferential position of the brush seal, the first BP inner side surface extends substantially parallel to a first plane, and the second BP inner side surface extends substantially parallel to a second plane, wherein the first plane is skewed from the second plane by an obtuse angle that is between one hundred and seventy-five degrees and one hundred and fifty degrees, and the first lengthwise portions of the plurality of bristles extend substantially parallel to the first plane and the third lengthwise portions extend substantially parallel to the second plane;

wherein at least some of the bristles are in contact with the BP inner side transition surface; and

wherein a first of the bristles comprises a metal bristle.

2. The multi-plane annular brush seal of claim 1 , wherein the BP inner side transition surface is arcuately shaped.

3. The multi-plane annular brush seal of claim 1 , wherein at least some of the bristle first lengthwise portions are in contact with the first BP inner side surface, at least some of the bristle second lengthwise portions are in contact with the BP inner side transition surface, and at least some of the bristle third lengthwise portions are in contact with the second BP inner side surface.

4. The multi-plane annular brush seal of claim 1 , wherein the plurality of bristles includes a subgroup of bristles, and for each bristle in the subgroup the first lengthwise portion is in contact with the first BP inner side surface, the second lengthwise portion is in contact with the BP inner side transition surface, and the third lengthwise portion is in contact with the second BP inner side surface.

5. The multi-plane annular brush seal of claim 1 , wherein the plurality of bristles includes a subgroup of bristles, and each bristle in the subgroup is in contact with back plate for its entire length, except for a length of the third lengthwise portion extending beyond a BP tip end of the back plate.

6. An assembly for a gas turbine engine, the assembly comprising:

a first static structure;

a second static structure; and

a multi-plane annular brush seal configured to seal a gap between the first static structure and the second static structure, the multi-plane annular brush seal attached to the first static structure and sealingly engaged with the second static structure, the multi-plane annular brush seal extending circumferentially about an axial centerline, and the multi-plane annular brush seal comprising a front plate, a back plate and a plurality of bristles attached to the front plate and the back plate at a base end of the multi-plane annular brush seal;

wherein each bristle has a first lengthwise portion extending from the base end, a second lengthwise portion, and a third lengthwise portion, and the second lengthwise portion of each respective bristle is disposed between the first lengthwise portion and third lengthwise portion of the respective bristle, and each third lengthwise portion terminates in a tip end;

wherein the front plate and back plate are configured to maintain the bristle first lengthwise portions substantially parallel to a first plane; and

wherein the back plate is configured to maintain the second lengthwise portion of the bristles through a transition region, and to maintain the bristle third lengthwise portions substantially parallel to a second plane;

wherein the first plane is skewed from the second plane by an obtuse angle that is between one hundred and seventy-five degrees and one hundred and fifty degrees; and

wherein at least some of the bristles are in contact with the back plate in the transition region.

7. The assembly of claim 6 , wherein the transition region is arcuately shaped.

8. The assembly of claim 7 , wherein the back plate includes a first BP inner side surface disposed adjacent the bristle first lengthwise portions, a BP inner side transition surface disposed adjacent the bristle second lengthwise portions, and a second BP inner side surface disposed adjacent the bristle third lengthwise portions.

9. The assembly of claim 8 , wherein the first BP inner side surface is skewed from the second BP inner side surface by an angle substantially equal to the obtuse angle.

10. The assembly of claim 9 , wherein at least some of the bristle first lengthwise portions are in contact with the first BP inner side surface, at least some of the bristle second lengthwise portions are in contact with the BP inner side transition surface, and at least some of the bristle third lengthwise portions are in contact with the second BP inner side surface.

11. The assembly of claim 9 , wherein the plurality of bristles includes a subgroup of bristles, and for each bristle in the subgroup the first lengthwise portion is in contact with the first BP inner side surface, the second lengthwise portion is in contact with the BP inner side transition surface, and the third lengthwise portion is in contact with the second BP inner side surface.

12. The assembly of claim 9 , wherein the plurality of bristles includes a subgroup of bristles, and each bristle in the subgroup is in contact with back plate for its entire length, except for a length of the third lengthwise portion extending beyond a BP tip end of the back plate.

13. An assembly for a gas turbine engine, the assembly comprising:

a multi-plane annular brush seal extending circumferentially about an axial centerline, the multi-plane annular brush seal comprising a front plate, a back plate and a plurality of bristles attached to the front plate and the back plate at a base end of the multi-plane annular brush seal;

each of the bristles including a first lengthwise portion, a second lengthwise portion and a third lengthwise portion, the first lengthwise portion extending from the base end, the second lengthwise portion between the first lengthwise portion and third lengthwise portion, and the third lengthwise portion extending to a tip end;

the front plate and the back plate configured to maintain the first lengthwise portion of each of the bristles substantially parallel to a first plane;

the back plate configured to maintain the second lengthwise portion of each of the bristles through a transition region, and the back plate further configured to maintain the third lengthwise portion of each of the bristles substantially parallel to a second plane;

the first plane skewed from the second plane by an angle greater than or equal to one hundred and fifty degrees; and

at least some of the bristles in contact with the back plate in the transition region.

14. The assembly of claim 13 , wherein the angle is less than or equal to one hundred and seventy-five degrees.

15. The assembly of claim 13 , wherein a first of the bristles comprises a metal bristle.

16. The assembly of claim 13 , further comprising:

a first static structure of the gas turbine engine; and

a second static structure of the gas turbine engine;

the multi-plane annular brush seal configured to create a seal between the first static structure and the second static structure, and the multi-plane annular brush seal attached to the first static structure and sealing engaged with the second static structure.

17. The assembly of claim 13 , further comprising:

a static structure of the gas turbine engine; and

a rotating structure of the gas turbine engine;

the multi-plane annular brush seal configured to create a seal between the static structure and the rotating structure, and the multi-plane annular brush seal attached to the static structure and sealing engaged with the rotating structure.

18. The assembly of claim 13 , wherein the assembly is configured such that

the front plate is configured adjacent a first plenum within the gas turbine engine;

the back plate is configured adjacent a second plenum within the gas turbine engine; and

during operation of the gas turbine engine, a fluid pressure within the first plenum is greater than a fluid pressure within the second plenum.

19. The assembly of claim 6 , wherein a first of the bristles is configured as a metal bristle.