U.S. patent application number 12/069512 was filed with the patent office on 2009-08-13 for replaceable blade tip shroud.
This patent application is currently assigned to Rolls-Royce North American Technologies, Inc.. Invention is credited to Douglas D. Dierksmeier, Tab M. Heffernan.
Application Number | 20090202355 12/069512 |
Document ID | / |
Family ID | 40939017 |
Filed Date | 2009-08-13 |
United States Patent
Application |
20090202355 |
Kind Code |
A1 |
Dierksmeier; Douglas D. ; et
al. |
August 13, 2009 |
Replaceable blade tip shroud
Abstract
One embodiment of the present invention is a blade with a
replaceable blade tip shroud that includes an airfoil shaped spar
extending from a leading edge to a trailing edge between a root end
and a tip end. It can also include a plurality of tiles coupled to
an exterior of the spar; a tip shroud positioned to overlap at
least a portion of the tip end of the spar; and means for anchoring
the tip shroud to the tip end of the spar.
Inventors: |
Dierksmeier; Douglas D.;
(Franklin, IN) ; Heffernan; Tab M.; (Plainfield,
IN) |
Correspondence
Address: |
KRIEG DEVAULT LLP
ONE INDIANA SQUARE, SUITE 2800
INDIANAPOLIS
IN
46204-2079
US
|
Assignee: |
Rolls-Royce North American
Technologies, Inc.
|
Family ID: |
40939017 |
Appl. No.: |
12/069512 |
Filed: |
February 11, 2008 |
Current U.S.
Class: |
416/226 ;
416/236R; 416/241B |
Current CPC
Class: |
Y02T 50/672 20130101;
F01D 5/225 20130101; Y02T 50/60 20130101; F01D 5/284 20130101 |
Class at
Publication: |
416/226 ;
416/236.R; 416/241.B |
International
Class: |
F01D 5/20 20060101
F01D005/20; F01D 5/14 20060101 F01D005/14 |
Claims
1. A blade with a replaceable blade tip shroud, comprising: a spar
extending from a leading edge to a trailing edge between a root end
and a tip end; a plurality of tiles coupled to an exterior of the
spar; a tip shroud positioned to overlap at least a portion of the
tip end of the spar; and means for anchoring the tip shroud to the
tip end of the spar.
2. The blade of claim 1, wherein the spar is airfoil shaped.
3. The blade of claim 2, wherein the tip shroud overlaps the entire
tip end of the spar, and wherein the tip shroud is configured to
retain at least one of the tiles in place against movement from the
root end toward the tip end.
4. The blade of claim 2, wherein the tip shroud includes at least
one groove to receive the means for anchoring the tip shroud to the
tip end of the spar.
5. The blade of claim 4, wherein the tip end of spar also includes
at least one groove to receive the means for anchoring the tip
shroud to the tip end of the spar.
6. The blade of claim 5, wherein the spar is metal and wherein the
tip shroud is metal.
7. The blade of claim 5, wherein the spar is metal and wherein the
tip shroud is ceramic.
8. An apparatus comprising a shroud tip held on a tip end of an
airfoil shaped spar by a retaining clip positioned within a pair of
grooves on the spar and a corresponding pair of grooves in the
shroud tip.
9. The apparatus of claim 8, wherein the retaining clip extends
from a leading edge of the airfoil shaped spar toward a trailing
edge of the airfoil shaped spar.
10. The apparatus of claim 9, wherein the pair of grooves extends
from a leading edge of the spar toward a trailing edge of the spar,
and wherein the pair of grooves do not extend all the way to the
trailing edge.
11. The apparatus of claim 9, wherein the retaining clip is airfoil
shaped.
12. The apparatus of claim 8, further comprising a plurality of
ceramic tiles coupled to the spar.
13. The apparatus of claim 12, wherein the shroud tip overlaps at
least one of the plurality of ceramic tiles and retains it in place
against movement toward the tip end.
14. The apparatus of claim 8, wherein the spar is metal and the
shroud tip is selected from the group consisting of a metal and a
ceramic.
15. The apparatus of claim 14, wherein the shroud tip is metal, and
wherein the shroud tip is a different metal than the spar.
16. A gas turbine engine blade with a replaceable tip shroud,
comprising: an airfoil shaped spar extending radially between a hub
end and a tip end, the spar extending substantially axially between
a leading edge and a trailing edge; a tip shroud positioned to at
least partially radially overlap the tip end of the airfoil shaped
spar; a retaining member extending from the leading edge toward the
trailing edge, the retaining member radially overlapping both the
tip shroud and the airfoil shaped spar.
17. The blade of claim 16, wherein the tip shroud includes a first
pair of channels shaped to receive the retaining member, and
wherein the tip end of the spar includes a corresponding second
pair of channels shaped to receive the retaining member.
18. The blade of claim 17, further comprising a plurality of tiles
coupled to the spar.
19. The blade of claim 18, wherein the tip shroud overlaps the
entire tip end of the spar, and wherein the tip shroud is
configured to retain at least one of the plurality of tiles in
place against movement from the root end toward the tip end.
20. The blade of claim 19, wherein the retaining member is an
airfoil shaped clip with a pair of prongs, and wherein the prongs
extend from the leading edge toward the trailing edge.
21. The blade of claim 20, wherein the spar is metal and the tip
shroud is selected from the group consisting of a metal and a
ceramic.
Description
BACKGROUND
[0001] The present invention relates generally to blade tip shrouds
and more particularly, but not exclusively, to a retaining system
for retaining a blade tip shroud to a turbine blade in a gas
turbine engine. Although, the present invention was developed for
use in gas turbine engines, certain applications may be outside
this field.
[0002] Blade tip shrouds typically wear during operation in gas
turbine engines and require replacement. Current blade tip shrouds
have issues including, for example, those respecting complexity of
geometry, manufacturing cost, assembly time, limitations on shroud
materials, ease of replacement, and fatigue life of the
replacement. Thus, there is a need for the development of
technology for removable blade tip shrouds within a gas turbine
engine. The present invention satisfies this need in a novel and
unobvious way.
SUMMARY
[0003] One embodiment of the present invention is a blade with a
replaceable blade tip shroud that includes an airfoil shaped spar
extending from a leading edge to a trailing edge between a root end
and a tip end. It also includes a plurality of tiles coupled to an
exterior of the spar; a tip shroud positioned to overlap at least a
portion of the tip end of the spar; and means for anchoring the tip
shroud to the tip end of the spar.
[0004] In one refinement the tip shroud overlaps the entire tip end
of the spar, and the tip shroud is configured to retain at least
one of the tiles in place against movement from the root end toward
the tip end.
[0005] In another refinement the tip shroud includes at least one
groove shaped to receive the means for anchoring the tip shroud to
the tip end of the spar.
[0006] In another refinement the tip end of spar also includes at
least one groove shaped to receive the means for anchoring the tip
shroud to the tip end of the spar.
[0007] In another refinement the spar is metal and the tip shroud
is metal.
[0008] In another refinement the spar is metal and the tip shroud
is ceramic.
[0009] Another embodiment of the present invention is an apparatus
including a shroud tip held on a tip end of an airfoil shaped spar
by a retaining clip positioned within a pair of grooves on the spar
and a corresponding pair of grooves in the shroud tip.
[0010] In one refinement the retaining clip extends from a leading
edge of the airfoil shaped spar toward a trailing edge of the
airfoil shaped spar.
[0011] In another refinement the pair of grooves extends from a
leading edge of the spar toward a trailing edge of the spar, and
the pair of grooves do not extend all the way to the trailing
edge.
[0012] In another refinement the retaining clip is airfoil
shaped.
[0013] In another refinement a plurality of ceramic tiles are
coupled to the spar.
[0014] In another refinement the tip shroud overlaps at least one
of the plurality of tiles and retains it in place against movement
toward the tip end.
[0015] In another refinement the spar is metal and the tip shroud
is selected from the group consisting of a metal and a ceramic.
[0016] In another refinement the tip shroud is metal, and the tip
shroud is a different metal than the spar.
[0017] Another embodiment of the present invention is a gas turbine
engine blade with a replaceable tip shroud, including an airfoil
shaped spar extending radially between a hub end and a tip end. The
spar extends substantially axially between a leading edge and a
trailing edge. The blade also includes a tip shroud positioned to
at least partially radially overlap the tip end of the airfoil
shaped spar. A retaining member extends from the leading edge
toward the trailing edge. The retaining member radially overlaps
both the tip shroud and the airfoil shaped spar.
[0018] In one refinement the tip shroud includes a first pair of
channels shaped to receive the retaining member, and the tip end of
the spar includes a corresponding second pair of channels shaped to
receive the retaining member.
[0019] In another refinement a plurality of tiles are coupled to
the spar.
[0020] In another refinement the tip shroud overlaps the entire tip
end of the spar. The tip shroud is configured to retain at least
one of the plurality of tiles in place against movement from the
root end toward the tip end.
[0021] In another refinement the retaining member is an airfoil
shaped clip with a pair of prongs. The prongs extend from the
leading edge toward the trailing edge.
[0022] In another refinement the spar is metal and the tip shroud
is selected from the group consisting of a metal and a ceramic.
[0023] One form of the present invention contemplates a replaceable
blade tip shroud for a blade. Other forms of the present invention
contemplate unique apparatuses, systems, devices, hardware,
methods, and combinations of these for defining a replaceable blade
tip shroud for a gas turbine engine. Further embodiments, forms,
objects, features and aspects of the present inventions shall
become apparent from the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The description herein makes reference to the accompanying
drawings wherein like reference numerals refer to like parts
throughout the several views, and wherein:
[0025] FIG. 1 is an illustrative schematic representation of a gas
turbine engine.
[0026] FIG. 2 is a perspective view of a gas turbine engine blade
according to an embodiment of the present invention.
[0027] FIG. 3 is a partial cross sectional view of a gas turbine
engine blade according to an embodiment of the present
invention.
[0028] FIG. 4 is a top cross sectional view of a gas turbine engine
blade according to an embodiment of the present invention.
[0029] FIG. 5 is a top view of a retaining clip according to an
embodiment of the present invention.
DETAILED DESCRIPTION
[0030] For purposes of promoting an understanding of the principles
of the invention, reference will now be made to the embodiments
illustrated in the drawings and specific language will be used to
describe the same. It will nevertheless be understood that no
limitation of the scope of the invention is thereby intended, such
alterations and further modifications in the illustrated device,
and such further applications of the principles of the invention as
illustrated therein being contemplated as would normally occur to
one skilled in the art to which the invention relates.
[0031] With reference to FIG. 1, there is illustrated a schematic
representation of a gas turbine engine 10. This non-limiting
depiction of gas turbine engine 10 includes a compressor section
20, a combustor section 30, and a turbine section 40. A person of
ordinary skill in the art should appreciate that there are a
multitude of ways in which the gas turbine engine components may be
linked together. For instance, the engine may include a fan stage,
a nozzle and/or additional compressors and turbine stages may be
added with intercoolers connecting between the compressor stages.
The present inventions are contemplated as being applicable with
virtually all types and configurations of gas turbine engines.
[0032] The gas turbine engines contemplated herein are applicable
for use in aircraft, as industrial power plants, and as propulsion
systems in vehicles and vessels. Industrial power plant
applications include, for example, pumping sets for gas and oil
transmission lines and electricity generation systems. The term
"aircraft" is generic and includes helicopters, airplanes,
missiles, unmanned space devices, transatmospheric vehicles and
other substantially similar devices.
[0033] Turbine section 40 includes at least one rotor or disk 50
having a plurality of turbine blades coupled thereto. A rotatable
shaft 60 is located within a mechanical housing/case 70 of the
turbine section 40 and is coupled to the rotor 50. The rotor 50 and
the shaft 60 may also be integrated together into a unitary
component. One form of the present invention contemplates that the
rotatable shaft 60 and the rotor 50 are supported by a plurality of
bearings. As the hot exhaust gas passes from the combustor section
30 the plurality of turbine blades rotate as the gas expands and
functions to extract work from the hot exhaust flow. While the
present disclosure will be generally described with reference to a
turbine blade it is contemplated that forms of the present
invention will be applicable to other gas turbine engine components
including, but not limited to, fan blades and compressor
blades.
[0034] Referring now to FIG. 2, there is illustrated a non-limiting
perspective view of a gas turbine engine blade 100. The present
invention contemplates a variety of blade designs and geometries.
Each turbine blade 100 includes an airfoil 120 that rotates with
the disk 50 (not shown in FIG. 2). Each airfoil 120 extends between
a leading edge 130 and a trailing edge 140 in a stream wise
direction and between an inner shroud or platform 150 and an outer
or tip shroud 160 in a spanwise direction. The airfoil 120 extends
radially outward from an outer surface 170 of the platform 150 from
a hub end 180 toward a tip end 190. The airfoil 120 is preferably
attached to the platform 150 proximate the hub end 180 of the
airfoil 120. It is contemplated that the airfoil 120 can be
integrally formed with the platform 150 through a casting process
or the like or alternatively may be mechanically joined via
welding, brazing or by any other joining method known to those
skilled in the art. However, airfoils that are separable from the
platform are also contemplated herein.
[0035] As described in further detail below, tip shroud 160 is
preferably removably attached to the airfoil 120 proximate the tip
end 190 of the airfoil 120. The tip shroud 160 includes an inner
surface 200 and an outer surface 210. The outer surface 210 of the
tip shroud 160 preferably includes at least one seal 220, and in
this particular embodiment includes two seals 220. The seals 220
are preferably knife seals, and minimize leakage of working fluid
from an outer flow path of air in the turbine section 40.
Additionally, the seals 220 preferably include an abradable
material layer 222 that is contactable with a housing (not shown in
FIG. 2) to provide a relatively tight seal. Other forms of the
present invention contemplate a layer of material or a seal such as
a blade track seal attached to the housing to prevent direct
contact between the abradable material layer 222 and the mechanical
housing. Over time, the abradable material layer 222 may degrade
from direct contact with the housing or the layer affixed to the
housing and require repair or replacement. It is contemplated that
the tip shroud 160 may be formed of a variety of materials
including, but not limited to, ceramic, intermetallic, ceramic
matrix composite, metallic, and a thermal barrier coated material.
Additionally, at least one form of the present invention
contemplates that the abradable material layer 222 is formed from a
different material than the tip shroud 160.
[0036] As partially described previously, each blade 100 is
attached to the rotor or disk 50 (not shown in FIG. 2) with an
attachment member 230 located inward from an inner surface 240 of
the platform 150. The attachment member 230 includes a connecting
joint 250 that connects the turbine blade 100 and the turbine disk
50. One form of the present invention contemplates that the
connecting joint 250 is formed from a common connection such as a
dovetail joint, or as this particular embodiment illustrates, a
"fir tree" design. Other forms contemplate different attachments
than a dovetail or fir tree joint known to those having ordinary
skill in the art.
[0037] As shown in FIG. 3, the airfoil 120 includes a spar or
structural member 262. The spar 262 includes an exterior surface
320 and extends between a root end (not shown) and a tip end 330.
The spar 262 preferably has an outer profile that corresponds to an
airfoil shape. In another form, the outer profile of the spar 262
does not correspond to an airfoil shape. The spar 262 is preferably
formed of a material suitable for operating within the environment
of a turbine section of a gas turbine engine. In one form of the
present invention, the spar 262 is formed of a heat-resistant
superalloy composition. There are various types of superalloy
compositions including, but not limited to, nickel-based or
cobalt-based superalloy compositions. The spar member 262, in one
form, has a unitary cast configuration. However, alternative
embodiments of the spar 262 contemplate an assembly of cast
components and/or wrought components. The spar 262 may be one of an
equiax, directionally solidified or a single crystal structure. In
still another form, the spar 262 is a cast integral single crystal
structure. Further, the present inventions contemplate that the
spar 262 may be formed of material appropriate for use in the
compressor section 20 of the gas turbine engine 10.
[0038] Referring now to FIGS. 3-5, the tip shroud 160 is preferably
removably coupled to the airfoil 120 by a retaining assembly 256.
The retaining assembly 256 includes a retainer receiving portion
defined by a pair of retaining channels or grooves 264 formed in
the spar 262 of the airfoil 120, a pair of retaining channels or
grooves 266 formed in the tip shroud 160, and a retaining member
268. A retainer receiving portion is formed by aligning the first
retaining channels 264 with the second retaining channel 266. The
retainer receiving portion preferably extends from the leading edge
130 to the trailing edge 140 and is operable to receive the
retaining member 268. The retaining member 268 is preferably in the
form of a clip including a tip portion 270 and a pair of legs or
prongs 272 (see FIG. 5). The retaining member 268 is preferably
inserted or fed into the leading edge side of the retainer
receiving portion 260. Once partially inserted, the legs 272 extend
around the spar 262 anchoring the tip shroud 160 to the airfoil
120. When inserted, the legs 272 preferably extend from the leading
edge 130 to the trailing edge 140. In one form the retaining member
268 extends entirely to the trailing edge 140, however in another
form the retaining member 268 extends only a portion of the
distance from the leading edge 130 to the trailing edge 140. The
retaining member 268 preferably has an airfoil shape. However, the
present application contemplates retaining member 268 having a
variety of shapes and is not limited to an airfoil shape unless
specifically provided to the contrary. In one form of the present
invention, a retaining member pushout access 274 is provided in a
trailing edge cooling channel 276 of the airfoil 120 to facilitate
removal of the retaining member 268. The tip shroud 160 is
preferably replaced when the abradable material layer 222 reaches a
certain wear level. It should be appreciated that the wear level
may be chosen based on maintenance standards or other factors known
to those having ordinary skill in the art. Additionally, the
retaining assembly 256 allows the tip shroud 160 to be formed from
a similar or different material than the airfoil 120. In some forms
of the present invention, a plurality of retaining assemblies 256
might be utilized in coupling the tip shroud 160 to the airfoil
120.
[0039] In one form of the present invention, the outer surface 300
of the airfoil 120 is defined by a plurality of cover tiles 310
coupled to at least a portion of the exterior surface 320 of the
spar 262, as shown in FIG. 3. Other embodiments of the present
invention contemplate that the outer surface of the airfoil 120
might include a different quantity of tiles 310 and/or have a
portion or portions not including a tile 310. Additionally, at
least one embodiment contemplates that the tiles 310 substantially
cover the exterior surface 320 of the spar 262. The tiles 310 may
be formed of a variety of materials including, but not limited to,
ceramic, intermetallic, ceramic matrix composite, metallic, and a
thermal barrier coated material. In one form the thermal barrier
coated material is a metallic material. The plurality of tiles 310
may be formed of the same material or may be formed of a different
material for some or all of the tiles 310. The present application
contemplates that the tiles 310 may have a three-dimensional-shaped
outer surface. In another form of the present application the outer
surface of at least one of the tiles 310 is substantially
flat/planar. Further, the present invention contemplates that the
resulting aggregate outer surface preferably has a
three-dimensional shape, and even more preferably the resulting
aggregate outer surface is an airfoil shape.
[0040] The tiles 310 are substantially adjacent and coupled to the
spar 262. One form of the present invention contemplates that the
plurality of tiles 310 are not permanently affixed to the spar 262.
Another form of the present invention contemplates that the
plurality of tiles 310 are mechanically coupled to the spar 262 by
a plurality of retaining elements (not shown). Still another form
of the present invention contemplates that at least one of the
plurality of tiles 310 is held in place by the tip shroud 160. As
shown in FIG. 3, tip shroud 160 is positioned to at least partially
overlap a portion of the tip end 330 of the spar 262 The tip shroud
160 preferably includes a cover engagement portion 400 operable to
engage a shroud engagement portion 410 of each of at least one of
the plurality of tiles 310. Another embodiment contemplates that
the tip shroud 160 overlaps the entire tip end 330 of the spar 262
thereby preferably retaining one or more of the plurality of tiles
310 against movement from the hub end 180 to the tip end 190. Other
forms contemplate that the plurality of tiles 310 may also be
retained by at least one coupler (not shown) to restrain movement
of the tiles 310 in an axial direction.
[0041] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment(s), but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims, which
scope is to be accorded the broadest interpretation so as to
encompass all such modifications and equivalent structures as
permitted under the law. Furthermore it should be understood that
while the use of the word preferable, preferably, or preferred in
the description above indicates that feature so described may be
more desirable, it nonetheless may not be necessary and any
embodiment lacking the same may be contemplated as within the scope
of the invention, that scope being defined by the claims that
follow. In reading the claims it is intended that when words such
as "a," "an," "at least one" and "at least a portion" are used,
there is no intention to limit the claim to only one item unless
specifically stated to the contrary in the claim. Further, when the
language "at least a portion" and/or "a portion" is used the item
may include a portion and/or the entire item unless specifically
stated to the contrary.
* * * * *