U.S. patent application number 12/230796 was filed with the patent office on 2010-03-04 for brush seal and turbine using the same.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Naoki Hagi, Takeaki Oya, Noriyoshi Uyama.
Application Number | 20100054924 12/230796 |
Document ID | / |
Family ID | 41725718 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100054924 |
Kind Code |
A1 |
Uyama; Noriyoshi ; et
al. |
March 4, 2010 |
Brush seal and turbine using the same
Abstract
A brush seal in which an increase in steady-state wear is
prevented and the influence of turbulence is eliminated is
provided. The invention includes a brush seal including brush seal
bristles formed of a plurality of wires and mounted to a seal box
in such a manner that one end thereof is in contact with a
downstream cylindrical portion; and a downstream support plate
mounted next to the brush seal bristles in a direction in which
combustion gas flows, for restricting the motion of the brush seal
bristles. The brush seal seals the combustion gas flowing between
the seal box and the downstream cylindrical portion. The brush seal
includes restraint bristles mounted opposite to the downstream
support plate and next to the brush seal bristles in the direction
in which the combustion gas flows. The restraint bristles have a
degree of elasticity such that the downstream cylindrical portion
is not damaged even if coming into contact with the downstream
cylindrical portion and such that the contact deformation of the
brush seal bristles is not hindered.
Inventors: |
Uyama; Noriyoshi;
(Hyogo-ken, JP) ; Hagi; Naoki; (Hyogo-ken, JP)
; Oya; Takeaki; (Hyogo-ken, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
41725718 |
Appl. No.: |
12/230796 |
Filed: |
September 4, 2008 |
Current U.S.
Class: |
415/173.1 ;
277/355 |
Current CPC
Class: |
F16J 15/3288 20130101;
F05D 2240/56 20130101; F01D 11/001 20130101; F01D 11/02 20130101;
F05D 2240/40 20130101 |
Class at
Publication: |
415/173.1 ;
277/355 |
International
Class: |
F01D 11/08 20060101
F01D011/08 |
Claims
1. A brush seal comprising: a bristle section formed of a plurality
of bristles and mounted to a stationary section in such a manner
that one end thereof is in contact with a rotating section; and a
brake section mounted next to the bristle section in a direction in
which fluid flows, for restricting the motion of the bristle
section, the brush seal sealing the fluid flowing between the
stationary section and the rotating section, wherein the brush seal
includes a restraint section mounted opposite to the brake section
and next to the bristle section in the direction in which the fluid
flows, the restraint section having a degree of elasticity such
that the rotating section is not damaged even if coming into
contact with the rotating section and such that the contact
deformation of the bristle section is not hindered.
2. The brush seal according to claim 1, wherein the restraint
section is disposed upstream of the bristle section in the
direction in which the fluid flows.
3. The brush seal according to claim 1, wherein the restraint
section is a bundle of bristles formed of a plurality of bristles
whose end is farther away from the rotating section than the end of
the bristles.
4. The brush seal according to claim 2, wherein the restraint
section is a bundle of bristles formed of a plurality of bristles
whose end is farther away from the rotating section than the end of
the bristles.
5. A turbine that uses the brush seal according to claim 1.
6. A turbine that uses the brush seal according to claim 2.
7. A turbine that uses the brush seal according to claim 3.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a brush seal and a turbine
using the same.
[0003] This application is based on Japanese Patent Application,
Publication No. 2008-121512, the content of which is incorporated
herein by reference.
[0004] 2. Description of Related Art
[0005] Gas turbines and steam turbines have, for example, a sealing
mechanism, around their rotation shafts, for preventing gas from
leaking from a high pressure side to a low pressure side.
[0006] One common example of this sealing mechanism is a labyrinth
seal, which is a non-contact seal.
[0007] The labyrinth seal has a limitation in reducing the amount
of leakage, that is, in improving sealing performance, because it
is a non-contact seal. Therefore, brush seals are starting to be
used to improve the sealing performance.
[0008] Brush seals have a plurality of bristles formed in a ring
shape (brush seal bristles) to achieve sealing in such a manner
that the ends of the brush seal bristles are in contact with a
rotating part.
[0009] The rotating part, for example, the rotor of a gas turbine
is deformed by a centrifugal force and heat caused by the operation
thereof, while on the other hand, a stator housing is also expanded
by the heat, causing a change in the distance between the brush
seal and the rotor.
[0010] Although this change is absorbed by the deflection of the
bristles, a deflection towards the downstream side may deteriorate
its sealing performance. Therefore, a back plate is provided
downstream of the brush seal bristles to prevent deflection towards
the downstream side.
[0011] For the deflection of the bristles, a space is provided
upstream of the bristles.
[0012] Since brush seals are contact seals, the ends of the
bristles that are in contact with the rotating part are worn down
with time.
[0013] In addition to this wear over time, if the fluid passing
through the brush seal bristles becomes turbulent, this will cause
the bristles to flutter (which is significant, in particular, at
the upstream side), thus breaking the bristles.
[0014] This breakage of the bristles causes the broken portion to
be out of contact with the rotor, thus deteriorating the sealing
performance of the brush seal.
[0015] The deterioration of the sealing performance of the brush
seal is problematic because, for example, it decreases the output
of the turbine.
[0016] Another problem is that the frequency of replacement of the
brush seal must be increased in order to prevent a decrease in
output, thus increasing maintenance costs.
[0017] One example of a solution to such problems is proposed in
Japanese Unexamined Patent Application, Publication No.
2001-73708.
[0018] It involves limiting the deflection of brush seal bristles
by providing a brake plate also upstream of the brush seal bristles
and reducing the occurrence of turbulence by providing a through
hole in the brake plate, thereby preventing, particularly, upstream
bristles from fluttering.
[0019] However, the solution described in Japanese Unexamined
Patent Application, Publication No. 2001-73708 strongly restricts
motion of the brush seal bristles to the vicinity of the rotor by
using the downstream back plate and the upstream brake plate, so
that the available length for deflection of the brush seal bristles
is short.
[0020] This increases the rigidity of the brush seal bristles,
which increases a contact pressure on the rotor, thus posing the
problem of increasing the wear of the bristles and the rotor in a
steady state.
[0021] Therefore, this approach does not yet sufficiently maintain
the sealing performance of the brush seal.
[0022] Moreover, since the back plate and the brake plate are
rigid, they may damage the rotor when coming into contact with the
rotor.
BRIEF SUMMARY OF THE INVENTION
[0023] In view of the above problems, an object of the present
invention is to provide a brush seal in which an increase in
steady-state wear is prevented and the influence of turbulence is
eliminated and a turbine using the same.
[0024] To solve the above problems, the present invention adopts
the following solutions.
[0025] A brush seal according to a first aspect of the present
invention includes a bristle section formed of a plurality of
bristles and mounted to a stationary section in such a manner that
one end thereof is in contact with a rotating section; and a brake
section mounted next to the bristle section in a direction in which
fluid flows, for restricting the motion of the bristle section, the
brush seal sealing the fluid flowing between the stationary section
and the rotating section, wherein the brush seal includes a
restraint section mounted opposite to the brake section and next to
the bristle section in the direction in which the fluid flows, the
restraint section having a degree of elasticity such that the
rotating section is not damaged even if coming into contact with
the rotating section and such that the contact deformation of the
bristle section is not hindered.
[0026] The brush seal according to the first aspect of the present
invention is configured such that, when the distance between the
stationary section and the rotating section changes, the change is
absorbed by the deflection of the bristle section. The bristle
section is limited in motion by the brake section mounted next
thereto in the fluid flowing direction, so that it deflects toward
the restraint section.
[0027] Since the restraint section has a degree of elasticity such
that the contact deformation of the bristle section is not
hindered, the restraint section can be elastically deformed to
absorb the deflection of the bristle section.
[0028] When the restraint section can absorb the deflection of the
bristle section, the contact frictional force of the bristle
section is not increased with changes in the distance between the
stationary section and the rotating section, which prevents an
increase in steady-state wear.
[0029] When turbulence occurs in fluid to cause parts of the
bristles to flutter, the motion of the bristles is restricted by
the restraint section because the force of the parts of the
bristles that acts on the restraint section is much smaller than
the force of the bristle section, that is, the whole of the
bristles.
[0030] Thus, the motion of parts of the bristles due to the
turbulence is prevented, which prevents fluttering, thereby
preventing breakage of the bristles caused by the fluttering.
[0031] This prevents deterioration of the sealing performance of
the brush seal, thereby preventing, for example, a decrease in the
output of the turbine and reducing the frequency of replacement of
the brush seal so that maintenance costs are decreased.
[0032] Moreover, since the restraint section has a degree of
elasticity such that the rotating section is not damaged even if
coming into contact with the rotating section, there is no
possibility of damaging the rotating section even if the restraint
section comes into contact with the rotating section.
[0033] If the restraint section comes into contact with the
rotating section, the rotating section is worn down and may be
damaged. Therefore, it is preferable that the end position of the
restraint section be farther away from the rotating section than
the end of the bristle section.
[0034] In the first aspect of the present invention, it is
preferable that the restraint section be disposed upstream of the
bristle section in the direction in which the fluid flows.
[0035] With this structure, the brake section is disposed at the
downstream side, which prevents the bristle section from deflecting
toward the downstream side, thereby preventing a decrease in
sealing performance.
[0036] In the brush seal according to the first aspect, it is
preferable that the restraint section be a bundle of bristles
formed of a plurality of bristles whose end is farther away from
the rotating section than the end of the bristles.
[0037] In this structure, the bristle bundle is formed of a
plurality of bristles. Therefore, the elasticity of the restraint
section in the axial direction and the radial direction can easily
be set to a specified value by appropriately adjusting the
elasticity of the bristles and the space among the bristles.
[0038] A turbine according to a second aspect of the present
invention uses the brush seal according to the first aspect.
[0039] The turbine according to the second aspect of the present
invention uses a brush seal in which an increase in steady-state
wear is prevented and the influence of turbulence is eliminated.
This prevents the deterioration of the sealing performance of the
brush seal and a decrease in the output of the turbine.
[0040] This also decreases the frequency of replacement of the
brush seal so that maintenance costs are reduced.
[0041] In the present invention, the restraint section has a degree
of elasticity such that the contact deformation of the bristle
section is not hindered. This prevents an increase in contact
frictional force with changes in the distance between the
stationary section and the rotating section, thereby preventing an
increase in steady-state wear.
[0042] Moreover, the motion of the bristles due to the turbulence
of fluid is restrained by the restraint section. This prevents
breakage of the bristles due to the turbulence.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0043] FIG. 1 is a longitudinal sectional view showing part of a
gas turbine incorporating an embodiment of the present
invention.
[0044] FIG. 2 is a longitudinal sectional view of a downstream
brush seal according to an embodiment of the present invention.
[0045] FIG. 3 is a front view of the downstream brush seal
according to the embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0046] Referring to FIGS. 1 to 3, an embodiment of the present
invention will be described.
[0047] FIG. 1 is a fragmentary longitudinal sectional view showing
the schematic structure of an inlet of a gas turbine 1 equipped
with a brush seal according to this embodiment.
[0048] The gas turbine 1 has, in its interior, a plurality of
moving blades 3 mounted to a rotor (not shown) and a plurality of
stationary blades 5 provided at the stator side around the rotor,
which are arranged alternately along the axis of the rotor (in the
lateral direction in FIG. 1), to form a combustion gas passage 7
therethrough. Individual adjacent stationary blades 5 and moving
blades 3 form a plurality of stages, which are arranged along the
axis of the rotor (in the lateral direction in FIG. 1)
[0049] A multistage structure is formed of continuous stages, that
is, first, second, third, and fourth stages, and so on, counting
from the upstream side where combustion gas flows in.
[0050] FIG. 1 shows blades from a first-row moving blade 3a to a
second-row moving blade 3b.
[0051] In FIG. 1, suffixes "a" and "b" added to the reference
numerals are used for distinguishing between the first row and the
second row; a indicates a part or a component of the first row and
b indicates a part or a component of the second row. In the
following specification, when the first and second rows are to be
distinguished, a and b are added, whereas when no particular
distinction is needed, parts or components are denoted only by
reference numerals without adding a or b.
[0052] The combustion gas supplied into the gas turbine 1 rotates
the moving blades 3 when flowing in the combustion gas passage 7 in
a flowing direction 9 to apply a rotating force to the rotor. This
rotating force rotates, for example, a generator (not shown)
connected to the rotor, to generate power.
[0053] The plurality of moving blades 3 are arranged radially and
are firmly mounted to the outer circumference of a disk (a rotating
section) 11 which protrudes from the periphery of the rotor (not
shown) in a cylindrical shape.
[0054] A large number of the stationary blades 5 are arranged
radially and are retained by a ring-shaped outer partition ring 15
and a ring-shaped inner partition ring (a stationary section) 17
which are firmly fixed to a turbine blade ring 13.
[0055] A sealing structure 19 for preventing leakage of combustion
gas is provided between the inner partition ring 17 and the disk
11.
[0056] The end of the inner partition ring 17 adjacent to the rotor
has a seal box 21 that constitutes the sealing structure 19.
[0057] The end of a disk 11a downstream in the flowing direction 9
has a double cylindrical portion that gradually decreases in
diameter in the downstream direction, that is, an upstream
cylindrical portion 23 and a downstream cylindrical portion 25.
[0058] The surface of the seal box 21 opposite the upstream
cylindrical portion 23 has an upstream brush seal (a brush seal)
27, and the surface opposite the downstream cylindrical portion 25
has a downstream brush seal (a brush seal) 29.
[0059] The upstream end of a disk 11b of the second row has a
cylindrical portion 31 which has substantially the same diameter as
the downstream cylindrical portion 25.
[0060] A labyrinth seal 33 is disposed between the cylindrical
portion 31 and the seal box 21.
[0061] A seal 35 is mounted between the downstream cylindrical
portion 25 and the cylindrical portion 31.
[0062] The upstream brush seal 27 and the downstream brush seal 29
have substantially the same structure, but different sizes.
Accordingly, a description of the downstream brush seal 29 will be
given and a duplicated description of the upstream brush seal 27
will be omitted hereinafter. Like or corresponding parts are given
the same names, and the upstream brush seal 27 and the downstream
brush seal 29 are not distinguished from each other in the
following description.
[0063] FIG. 2 is an enlarged longitudinal sectional view of the
downstream brush seal 29 in FIG. 1. FIG. 3 is a front view of the
downstream brush seal 29.
[0064] The downstream brush seal 29 is mounted in a ring-shaped
installation space 22 provided under the lower surface of the seal
box 21.
[0065] The downstream brush seal 29 is a ring-shaped component,
which is circumferentially divided into a plurality (for example,
six) of brush seal segments 37, as shown in FIG. 3.
[0066] The brush seal segments 37 include brush seal bristles (a
bristle section) 39, restraint bristles (a restraint section, a
bundle of bristles) 41, an upstream support plate 43, and a
downstream support plate 45 (a brake section).
[0067] The brush seal bristles 39 are formed of wires (bristles) 47
with a diameter of 0.1 to 0.2 mm (in this embodiment, for example,
0.13 mm) and a length of 30 to 40 mm, and are bundled together with
a wire density of about 60 to 100 per 3 mm.sup.2 (in a
cross-sectional view parallel to the rotor axis).
[0068] The wires 47 are disposed at a predetermined angle relative
to the radius of the downstream brush seal 29, that is, inclined in
the rotating direction 10 of the downstream cylindrical portion 25
(see FIG. 3).
[0069] The wires 47 are made of a cobalt-based heat-resisting
alloy, for example, HAYNES alloy (a trademark of Haynes
International, Inc.) No. 25.
[0070] The outer circumferential ends of the brush seal bristles 39
are clamped by an upstream retainer 49 and a downstream retainer 51
which are rectangular cross-section arc-shaped components. The
outer circumferential end faces of the brush seal bristles 39 are
fixed across the upstream retainer 49 and the downstream retainer
51 by a weld 53.
[0071] The restraint bristles 41 are formed of wires (bristles) 55
with a diameter of 0.1 to 0.2 mm (in this embodiment, for example,
0.13 mm) and a length of 15 to 18 mm, and are bundled together with
a wire density of about 60 to 100 per 3 mm.sup.2 (in a
cross-sectional view parallel to the rotor axis).
[0072] The wires 55 are made of a cobalt-based heat-resisting
alloy, for example, HAYNES alloy (a trademark of Haynes
International, Inc.) No. 25.
[0073] The wires 55 have low elasticity in themselves but can
provide higher elasticity when bundled. The elasticity of the
restraint bristles 41 can be adjusted to a predetermined value by
adjusting the density of the wires 55.
[0074] The wires 55 are disposed at a predetermined angle relative
to the radius of the downstream brush seal 29, that is, inclined in
the rotating direction 10 of the downstream cylindrical portion 25
(see FIG. 3).
[0075] The outer circumferential end faces of the restraint
bristles 41 are fixed to a restraint-bristle retainer 57 which is a
rectangular cross-section arc-shaped component by a weld 59.
[0076] The upstream support plate 43 is a substantially rectangular
cross-section arc-shaped component.
[0077] The upstream support plate 43 has, substantially at the
center of the upstream surface in the radial direction, a recessed
portion 61 in which a ring-shaped protruding portion 63 provided at
the lower part of the installation space 22 in the seal box 21 is
to be fitted.
[0078] The upstream support plate 43 has, in the vicinity of the
outer circumference in the downstream surface in the radial
direction, an upstream retaining groove 65 for accommodating the
upstream retainer 49.
[0079] The width, that is, the radial length, of the upstream
retaining groove 65 is set a little larger than the total length of
the upstream retainer 49 and the weld 53.
[0080] The downstream surface of the upstream support plate 43 has,
from the inner circumferential end to the vicinity of the upstream
retaining groove 65, a restraint-bristle retaining recessed portion
67 for accommodating the restraint bristles 41.
[0081] The restraint-bristle retaining recessed portion 67 has a
restraint-bristle retaining groove 69 for accommodating the
restraint-bristle retainer 57 substantially at the center in the
radial direction.
[0082] The width, that is, the radial length, of the
restraint-bristle retaining groove 69 is set a little larger than
the total length of the restraint-bristle retainer 57 and the weld
59.
[0083] The upstream surface of the upstream support plate 43 has,
substantially in the radially outer circumference, a rotation stop
groove 71 extending in the radial direction.
[0084] The downstream support plate 45 is a substantially
rectangular cross-section arc-shaped component.
[0085] The downstream support plate 45 has, substantially in the
center of the downstream surface in the radial direction, a
recessed portion 75 in which a ring-shaped protruding portion 73
provided at the lower part of the installation space 22 in the seal
box 21 is to be fitted.
[0086] The downstream support plate 45 has, in the vicinity of the
outer circumference in the upstream surface in the radial
direction, a downstream retaining groove 77 for accommodating the
downstream retainer 51.
[0087] The width, that is, the radial length, of the downstream
retaining groove 77 is set a little larger than the total length of
the downstream retainer 51 and the weld 53.
[0088] The upstream surface of the downstream support plate 45 is
cut off from the downstream retaining groove 77 to the inner
circumferential end by a depth corresponding to the axial length of
the brush seal bristles 39 so as to accommodate the brush seal
bristles 39.
[0089] The upstream support plate 43 and the downstream support
plate 45 are butted against each other, with the upstream retainer
49 accommodated in the upstream retaining groove 65 and the
downstream retainer 51 accommodated in the downstream retaining
groove 77, and with the restraint-bristle retainer 57 accommodated
in the restraint-bristle retaining groove 69, and then the outer
circumferences are joined to form the brush seal segment 37.
[0090] The brush seal segments 37 are combined in sequence so that
the recessed portions 61 and 75 are fitted on the protruding
portions 63 and 73 of the installation space 22 in the seal box 21,
respectively.
[0091] At that time, a rotation stop bolt 79 fixed to the seal box
21 and to be engaged with the rotation stop groove 71 is mounted to
define the circumferential positions of the individual brush seal
segments 37 and to limit the circumferential movements of the
individual brush seal segments 37.
[0092] The operation of the upstream brush seal 27 and the
downstream brush seal 29 of this embodiment, having the above
structure, will be described.
[0093] When the gas turbine 1 is started, combustion gas is
supplied from a combustion apparatus (not shown) into the
combustion gas passage 7.
[0094] The supplied combustion gas is expanded by the stationary
blades 5 when flowing through the combustion gas passage 7 in the
flowing direction 9 to generate velocity energy, so that it changes
in flowing direction to produce kinetic energy in the axial
rotating direction.
[0095] The combustion gas energy converted to the velocity energy
is absorbed by the moving blades 3 to rotate them. The rotor
rotates by this rotation of the moving blades 3. This rotating
force rotates, for example, a generator (not shown) connected to
the rotor to generate power.
[0096] Since the energy is thus absorbed by the individual moving
blades 3 in sequence, the combustion gas is higher in temperature
and pressure at the upstream side.
[0097] The larger the amount of combustion gas that passes through
the combustion gas passage 7, the higher the energy efficiency
is.
[0098] Therefore, the upstream brush seal 27, the downstream brush
seal 29, and the labyrinth seal 33 seal combustion gas that moves
from the first-row moving blade 3a to the second-row moving blade
3b without passing through the combustion gas passage 7.
[0099] When the gas turbine 1 is driven, the moving blades 3 are
off-centered outwardly because a centrifugal force acts on the
moving blades 3. The rotor and the stationary blades 5 are expanded
because they are heated by the combustion gas.
[0100] This changes the distance between the seal box 21 at the
stator side and the disk 11 at the rotor side, which generally
brings them closer together.
[0101] When the seal box 21 and the disk 11 come close to each
other in this way, the brush seal bristles 39 are pushed by the
downstream cylindrical portion 25 to move to the outer
circumference.
[0102] When the outer circumferential ends of the brush seal
bristles 39 come into contact with the outer circumferential
surface of the downstream retaining groove 77, the brush seal
bristles 39 cannot move to the outer circumference any more, so
that the brush seal bristles 39 are deflected.
[0103] At that time, the movement of the downstream ends of the
brush seal bristles 39 is firmly limited by the downstream support
plate 45, so that the brush seal bristles 39 are deflected
upstream, that is, entirely moved upstream. That is, the entireties
of the brush seal bristles 39 are moved, thus remarkably increasing
pressure.
[0104] Thus, this prevents the brush seal bristles 39 from
deflecting downstream, thereby preventing a decrease in sealing
performance.
[0105] The brush seal bristles 39 are deflected toward the
restraint bristles 41 mounted next thereto at the upstream side to
apply high pressure thereto, whereas the restraint bristles 41 have
a specific elasticity which is the total of the elasticity of the
gaps among the wires 55 and the elasticity of the wires 55
themselves in the flowing direction 9, so that the restraint
bristles 41 can absorb the movement of the brush seal bristles 39,
that is, prevent the brush seal bristles 39 from moving by the
elasticity.
[0106] Thus, the restraint bristles 41 absorb the contact pressure
that acts between the brush seal bristles 39 and the downstream
cylindrical portion 25, so that the contact frictional force
therebetween is hardly increased.
[0107] Since the contact frictional force is not increased, an
increase in steady-state wear can be prevented.
[0108] If turbulence occurs in the combustion gas flowing between
the brush seal bristles 39 and the downstream cylindrical portion
25 to cause parts of the wires 47 to flutter, the force generated
by the parts of the wires 47 is much smaller than that when the
whole of the brush seal bristles 39 deflect.
[0109] Thus, this force is not large enough to overcome the elastic
force of the restraint bristles 41 to deform them, so that this
force does not deform the restraint bristles 41. In other words,
the restraint bristles 41 can restrain the movement of parts of the
wires 47.
[0110] This prevents the movement of parts of the wires 47 due to
turbulence and prevents fluttering, thereby preventing breakage of
the wires 47 caused by the fluttering.
[0111] This prevents the deterioration of the sealing performance
of the downstream brush seal 29 and the upstream brush seal 27,
thereby preventing, for example, a decrease in the output of the
turbine and reducing the frequency of replacement of the brush
seal, thus decreasing maintenance costs.
[0112] Since the end position of the restraint bristles 41 is
separated from the surface of the downstream cylindrical portion 25
more than the end position of the brush seal bristles 39, there is
little possibility that the restraint bristles 41 come into contact
with the downstream cylindrical portion 25 even if the distance
between the seal box 21 and the disk 11 at the rotor side is
decreased.
[0113] Moreover, even if the restraint bristles 41 come into
contact with the downstream cylindrical portion 25, there is little
possibility that the surface of the downstream cylindrical portion
25 is worn down or damaged because the restraint bristles 41 are
formed of the thin, weak wires 55.
[0114] The upstream brush seal 27 also operates in the same way as
the downstream brush seal 29 described above.
[0115] The upstream brush seal 27 and the downstream brush seal 29
of this embodiment, described above, are not limited to the above
description and may be modified variously without departing from
the spirit of the present invention.
[0116] For example, while this embodiment uses the restraint
bristles 41 which is a bundle of the wires 55 as a restraint
section, the restraint section needs only enough elasticity to
limit the movement of the wires 47 while absorbing the deflection
of the brush seal bristles 39; for example, a thin sheet-like
restraint section or a layer thereof may be used.
[0117] Although this embodiment is applied to the sealing structure
between the stationary blades and the moving blades, the present
invention is not limited to that and may be applied to other
components.
[0118] Furthermore, the present invention is not necessarily
applied to gas turbines but may be applied to other rotary
machines, for example, a steam turbine.
* * * * *