STATIC OUTSIDE DIAMETER BRUSH SEAL ASSEMBLY
TECHNICAL FIELD
[0001] The present invention relates to static outside diameter sealing brush seals.
BACKGROUND
[0002] Brush seals provide a technology for sealing high pressure areas from low pressure
areas, for example, areas associated with gas turbine engines. Typically, brush seals inhibit the
flow of a gas in a stream along a shaft.
SUMMARY
[0003] An outside diameter brush seal assembly is disclosed. The brush seal assembly
includes a first static component, a second static component, and a brush seal. The first and
second static components may be configured to form a flow path from a first pressure cavity to a
second pressure cavity. The brush seal includes a plurality of bristles that extend in a radially
outward direction from the first static component to form a seal against the second static
component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Embodiments of the invention will now be described, by way of example, with
reference to the accompanying drawings, wherein:
[0005] FIG. 1 is a perspective view of an embodiment of a brush seal assembly;
[0006] FIG. 2 is a front view of the assembly illustrated in FIG. 1;

[0007] FIG. 3 is a partial section view taken along lines A-A in FIG. 2 and generally
illustrating a portion of second static component;
[0008] FIG. 4 is a perspective view of another embodiment of a brush seal assembly;
[0009] FIG. 5 is a side view of the assembly shown in FIG. 4; and
[00010] FIG. 6 is a partial sectional view the assembly shown including a plurality of brush
seals.
DETAILED DESCRIPTION
[00011] Reference will now be made in detail to embodiments of the present invention,
examples of which are described herein and illustrated in the accompanying drawings. While the
invention will be described in conjunction with embodiments, it will be understood that they are
not intended to limit the invention to these embodiments. On the contrary, the invention is
intended to cover alternatives, modifications and equivalents, which may be included within the
spirit and scope of the invention as defined by the appended claims.
[00012] FIG. 1 generally illustrates a perspective view of a brush seal assembly 10
according to an embodiment of the invention. The brush seal assembly 10 may be comprised of
two or more segments that form a portion of an outer periphery of the assembly. For example,
without limitation, the assembly 10 illustrated in FIG. 1 includes two separate segments - shown
separated by separation lines 12a, 12b - each shown extending approximately 180°. FIG. 2
generally illustrates a front view of the assembly 10 shown in FIG. 1.
[00013] The assembly may be connected with, and in some cases may include, other second
static components, such as various casings (e.g., item 18 in Fig. 3). When connected with a
second component, the assembly 10 may, for example and without limitation, be rotated or spun
into an engaged position. Alternatively, portions of the assembly may be configured to separate
and then to overlap in their operational configuration to provide for improved assembly.

[00014] As illustrated in FIG. 3, the brush seal assembly 10 may include a brush seal
(which may also be referred to as a "brush seal insert") 14 that provides a functional or operative
seal between a first static component 16 and a second static component 18, which may be
associated with or connected to elements of a housing 18. As used herein, the term "static" is
meant to generally pertain to substantially stationary, non-rotating components. However, it is
noted that with "static" components there may still be some measure of movement, for example,
expansions and/or contractions in response to changes in thermal conditions.
[00015] In an embodiment, first static component 16 includes a groove or receiving portion
20 for receiving a portion of the brush seal 14. Groove or receiving portion 20 may, for
example, have a length taken along a longitudinal direction of the assembly of at least 0.050
inches. In an embodiment, the first static component 16 may have a length taken along a
longitudinal direction of the assembly of .510 inches ± .002 inches.
[00016] Brush seal 14 may include a segment or ring 22 that is retained within a portion of
the groove or receiving portion 20 of the first static component 16. Brush seal 14 further
includes a plurality of bristles (generally represented as 24) that extend in a radially outward
direction from the first static component. An outer portion of the bristles 24 form a seal against
second static component 18. Bristles 24 may, for example, be comprised of a bronze alloy, a
ceramic material, a stainless steel alloy, a cobalt-based alloy, or a nickel-based alloy. In an
embodiment, bristles 24 may be interference-fit within the groove or receiving portion 20 of first
static component 16 and, for some applications, may not include a weld bead.
[00017] First and second static components 16, 18 can be configured to form a flow path
(generally identified as 26) from a first (e.g. high-pressure) pressure cavity HP to a second (e.g.,
low-pressure) pressure cavity LP. Brush seal 14 may be interposed along the flow path 26
formed between the first and second static components 16, 18, functionally separating and
limiting the amount of flow between first and second pressure cavities HP,LP. In an
embodiment, the seal 14 may be provided such that only a portion of the bristles 24 are
configured to sealingly engage or contact a portion of second static component. Further in an
embodiment, the brush seal does not include a static seal (e.g., a labyrinth seal) with respect to

the second static component. That is, conventional labyrinth-type seals generally require at least
one labyrinth tooth for use as a backing. The present invention does not require such a tooth or
backing.
[00018] In an embodiment, brush seal ring or segment 22 may include one or more side
plates or rails (e.g., 28, 30) adjacent to the bristles and received within a portion of the receiving
portion 20 of first static component 16. The one or more brush seal side plates or rails may,
without limitation, be comprised of stainless steel or a nickel-based alloy. For some
embodiments, all or a portion of the one or more side plates or rails 28,30 may be flexible and/or
linear. Moreover, the side plates or rails may be configured to be generally annular and, if
desired, may comprise a rigid ring.
[00019] For some embodiments, first and second static components 16, 18 may be
comprised of different materials that have different rates of thermal expansion. Differing rates of
thermal expansion of first and second static components 16, 18 in proximity to the brush seal 14
can provide a gap between surfaces of first and second static components under one or more
operational conditions. For many applications, a large difference in thermal expansion may be
anticipated. Many conventional static brush seals may only permit a radial expansion of 0.050
inch. As discussed further herein, embodiments of the present invention may permit radial
movement up to ½ inch or more.
[00020] Because the gap between the surfaces of the first and second static components
16, 18 may change, it may be desirable to account for the gap, and the potential wear and tear on
the associated bristles 28, with the selection of materials based, for instance, on desired results
(e.g., gap control) in connection with anticipated operating conditions. For many applications,
the assembly may also take into account the radial movement of the bristles 28. For example,
without limitation, if the bristles are generally in operational contact with the second static
component 18, and the gap between the first and second static components 16, 18 becomes
reduced, in an embodiment the bristles are provided with some measure of responsive radial
movement. In the embodiment illustrated in FIG. 3, the brush seal 14, and consequently the
associated bristles may have some radial "play" within groove or receiving portion 20. In some

instances, such range of movement can relieve or reduce contact stresses between the bristles 24
and the second static component 18.
[00021] For some embodiments, bristles 24 have a range, for example, of from 0.050 inches
to 0.060 inches. In another embodiment, bristles 24 may have a radial range of movement of at
least 0.060 inches. In yet other embodiments, bristles 24 may have a radial range of movement of
0.20 inches or more. Moreover, for some applications, it may be desirable to provide bristles 24
to form a bristle pack having a density that is sufficient to prevent splaying apart
circumferentially when the bristles extend radially outwardly in a contact configuration. That is,
the assembly can be provided to maintain substantially constant interference and maintain pack
density. In some embodiments, the bristles have a uniform pack density throughout their extent
from the first static component 16 to an outer sealing end that sealingly engaging a second static
component 18. If desired, particularly for ensuring that the brush seal remains flexible and does
not need to be too large, the brush seal 14 may include a side plate or rail with a moment of
inertia of 5 x 10"5 inches4 or less. Additionally, in an embodiment, bristles 24 may be oriented at
an angle of 20 to 90 degrees tangent to a sealing surface of the second static component 18.
[00022] The invention is not, however, limited to brush seal assemblies having a single
brush seal. FIGS. 4-6 generally represent additional embodiments of the invention with a
plurality of brush seals. More specifically, FIG. 4 illustrates a perspective view of an
embodiment of an assembly 10' shown with three outer diameter brush seals 14a, 14b, 14c, each
brush seal extending circumferentially, or substantially circumferentially, around the outer
perimeter of the assembly. FIG. 5 is a side view of the assembly shown in FIG. 4.
[00023] FIG. 6 is partial sectional view of the assembly 10' similar to the view shown in
FIG. 3. As generally shown, one or more brush seals 14a, 14b, 14c may be included with the
assembly 10'. In a similar fashion as the previously described embodiments, brush seals
14a,14b,14c may be interposed along a flow path 26' formed between the first and second static
components 16', 18', functionally separating and limiting the amount of flow between first and
second pressure cavities HP',LP'.

[00024] The foregoing descriptions of specific embodiments of the present invention have
been presented for purposes of illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise forms disclosed, and various modifications and
variations are possible in light of the above teaching. The embodiments were chosen and
described in order to explain the principles of the invention and its practical application, to
thereby enable others skilled in the art to utilize the invention and various embodiments with
various modifications as are suited to the particular use contemplated. It is intended that the
scope of the invention be defined by the claims appended hereto and their equivalents.

CLAIMS
What is claimed is:
1. An outside diameter brush seal assembly (10), comprising:
a first static component (16) including a groove or receiving portion (20);
a second static component (18), the first and second static components (16,18)
configured to form a flow path (26) from a first pressure cavity (HP) to a second pressure cavity
(LP); and
a flexible brush seal (14) including a segment or ring (22) retained within a portion of the
groove or receiving portion (20) of the first static component (16), the brush seal (14) further
including a plurality of bristles (24) that extend in a radially outward direction from the first
static component (16) to form a brush seal (14) against the second static component (18);
wherein the brush seal (14) is interposed along said flow path (26) between said first and
second pressure cavities (HP, LP), and only the bristles (24) are configured to sealingly engage
or contact a portion of the second static component (18).
2. The brush seal assembly (10) of claim 1, wherein the brush seal (14) is devoid of a static
seal with respect to the second static component (18).
3. The brush seal assembly (10) of claim 1, wherein the brush seal (14) assembly is devoid
of a labyrinth seal.
4. The brush seal assembly (10) of claim 1, wherein the brush seal (14) limits the amount of
flow between said first and second pressure cavities (HP, LP).
5. The brush seal assembly (10) of claim 1, wherein the brush seal ring or segment (22)
includes one or more side plates or rails (28, 30) adjacent to the bristles (24) and received within
a portion of the receiving portion (20) of the first static component (16).
6. The brush seal assembly (10) of claim 5, wherein the one or more side plates or rails (28,
30) are flexible.

7. The brush seal assembly (10) of claim 5, wherein the side plates or rails (28, 30) are
annular.
8. The brush seal assembly (10) of claim 5, wherein the side plates or rails (28, 30)
comprise a rigid ring.
9. The brush seal assembly (10) of claim 5, wherein the side plates or rails (28, 30) are
linear.
10. The brush seal assembly (10) of claim 1, wherein the first and second static components
(16,18) are comprised of different materials and have different rates of thermal expansion.
11. The brush seal assembly (10) of claim 10, wherein selection of components having
different thermal expansion rates of the first and second static components (16,18) in proximity
to the brush seal (14) provides a gap between surfaces of the first and second static components
(16,18) under one or more operational conditions.
12. The brush seal assembly (10) of claim 1, wherein the bristles (24) have a radial range of
movement of at least 0.060 inches.
13. The brush seal assembly (10) of claim 1, wherein the bristles (24) have a radial range of
movement of 0.20 inches or more.
14. The brush seal assembly (10) of claim 1, wherein the bristles (24) have a radial range of
movement from 0.050 inches to 0.060 inches.
15. The brush seal assembly (10) of claim 1, wherein the bristles (24) have a bristle pack
density that is sufficient to prevent splaying apart circumferentially when the bristles extend
radially outwardly in a contact configuration.
16. The brush seal assembly (10) of claim 5, wherein the side plate or rail (28, 30) has a
moment of inertia of 5 x 10"5 inches4 or less.

17. The brush seal assembly (10) of claim 1, wherein the bristles (24) have a uniform pack
density throughout their extent from the first static component (16) to a sealing end.
18. The brush seal assembly (10) of claim 1, wherein the bristles (24) are oriented at an angle
of 30 to 90 degrees tangent to a sealing surface of the second static component (18).
19. The brush seal assembly (10) of claim 1, wherein the bristles (24) are interference-fit
within the groove or receiving portion (20) of the first static component (16).
20. The brush seal assembly (10) of claim 1, wherein the groove or receiving portion (20) has
a length taken along a longitudinal direction of the assembly (10) of at least 0.050 inches.
21. The brush seal assembly (10) of claim 1, wherein the groove or receiving portion (20) has
a length taken along a longitudinal direction of the assembly of .510 inches ± .002 inches.
22. The brush seal assembly (10) of claim 5, wherein the one or more brush seal side plates
or rails (28,. 30) is comprised of stainless steel or a nickel-based alloy.
23. The brush seal assembly (10) of claim 1, wherein the bristles (24) are comprised of a
bronze alloy, a ceramic material, a stainless steel alloy, a cobalt-based alloy, or a nickel-based
alloy.
24. An outside diameter brush seal assembly (10% comprising:
a first static component (16') including a groove or receiving portion (20');
a second static component (18% the first and second static components (16', 18')
configured to form a flow path (26') from a first pressure cavity (HP')to a second pressure cavity
(LP1); and
a plurality of flexible brush seals (14a, 14b, 14c), each brush seal including a segment or
ring (22') retained within a portion of the groove or receiving portion (20') of the first static
component (16'), the brush seal (14a, 14b, 14c) further including a plurality of bristles 24') that
extend in a radially outward direction from the first static component (16')to form a brush seal
against the second static component (18');

wherein the plurality of brush seals (14a, 14b, 14c) are interposed along said flow path
(26') between said first and second pressure cavities (HP1, LP'), and only the bristles (24') are
configured to sealingly engage or contact a portion of the second static component (18').
25. The assembly (10') of claim 24, wherein the plurality of brush seals (14a, 14b, 14c) are
devoid of a static seal.
26. The assembly (10') of claim 24, wherein the brush seals (14a, 14b, 14c) include one or
more side plates or rails (28', 30') adjacent to the bristles (24') and received within a portion of
the receiving portion (20')of the first static component (16').
27. The brush seal assembly (10') of claim 24, wherein the first and second static components
(16', 18') have different rates of thermal expansion.
28. An outside diameter brush seal assembly (10') for providing a brush seal (14') with
respect to a second static component (18'), the brush seal (14') comprising:
a first static component (16') including a groove or receiving portion (20'); and
a flexible brush seal (14') including a segment or ring (22') retained within a portion of
the groove or receiving portion (20') of the first static component (16'), the brush seal (14')
further including a plurality of bristles (24') that extend in a radially outward direction from the
first static component (16');
wherein the first static component (16') can be positioned relative to said second static
component (18') to provide a brush seal (14') against said second static component (18') and form
a flow path 26') between the first static component (16') and said second static component (18')
from a first pressure cavity (HP1) to a second pressure cavity (LP').
29. The brush seal assembly (101) of claim 28, wherein the first static component (16') is
comprised of different material than said second static component (181).
30. The brush seal assembly (10') of claim 28, wherein the first static component (16') has a
different rate of thermal expansion than said second static component (18').

31. The brush seal assembly (10') of claim 28, wherein the brush seal (14') is devoid of a
static seal for sealing communication with said second static component (18').
32. The brush seal assembly (10') of claim 28, wherein the brush seal (14') is devoid of a
labyrinth seal for sealing communication with said second static component (18').
33. The brush seal assembly (10') of claim 28, wherein the brush seal ring or segment (22')
includes one or more side plates or rails (28', 30') adjacent to the bristles (24') and received
within a portion of the receiving portion (201) of the first static component (16').
34. The brush seal assembly (10') of claim 28, wherein the bristles (24') have a radial range
of movement of at least 0.060 inches.
35. The brush seal assembly (10') of claim 28, wherein the bristles (24') have a radial range
of movement from 0.050 inches to 0.060 inches.
36. The brush seal assembly (10') of claim 28, wherein the bristles (24') have a bristle pack
density that is sufficient to prevent splaying apart circumferentially when the bristles (24') extern
radially outwardly in a contact configuration.
37. The brush seal assembly (10') of claim 33, wherein the side plate or rail (28', 30') has a
moment of inertia of 5 x 10-5 inches4 or less.
38. The brush seal assembly (10') of claim 28, wherein the bristles (24') have a uniform pack
density throughout their extent from the first static component (16') to a sealing end.
39. The brush seal assembly (10') of claim 28, wherein the bristles (24') are oriented at an
angle of 30 to 90 degrees tangent to a sealing surface of the second static component (18').
40. The brush seal assembly (10') of claim 28, wherein the bristles (24') are interference-fit
within the groove or receiving portion (20') of the first static component (16').
41. The brush seal assembly (10') of claim 28, including a plurality of flexible brush seals
(14a, 14b, 14c).

An outside diameter brush seal assembly (10) is disclosed. The brush seal assembly (10)
includes a first static component (16), a second static component (18), and a brush seal (14). The
first and second static components (16, 18) may be configured to form a flow path (26) from a
first pressure cavity (HP) to a second pressure cavity (LP). The brush seal (14) includes a
plurality of bristles (24) that extend in a radially outward direction from the first static
component (16) to form a brush seal (14) against the second static component (18).