U.S. patent application number 12/030317 was filed with the patent office on 2009-08-13 for rotating assembly for a turbomachine.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Kevin Leon Bruce, Ronald Ralph Cairo, Richard Gordon Rollings.
Application Number | 20090202344 12/030317 |
Document ID | / |
Family ID | 40686246 |
Filed Date | 2009-08-13 |
United States Patent
Application |
20090202344 |
Kind Code |
A1 |
Bruce; Kevin Leon ; et
al. |
August 13, 2009 |
ROTATING ASSEMBLY FOR A TURBOMACHINE
Abstract
A rotating assembly for a turbomachine includes a plurality of
rotating members that extend radially outward from a central hub.
Each of the plurality of rotating members includes a base portion
detachably mounted to the central hub, a tip portion, a mid-span
portion that extends between the base portion and the tip portion,
and a shroud portion positioned at one of the tip portion and the
mid-span portion. The shroud portion includes a pressure side and a
suction side. At least one hard face interface member is secured to
at least one of the suction side and the pressure side of the
shroud portion. The at least one hard face interface member is both
mechanically interlocked with, and metallurgically bonded to, the
shroud portion.
Inventors: |
Bruce; Kevin Leon; (Greer,
SC) ; Cairo; Ronald Ralph; (Greer, SC) ;
Rollings; Richard Gordon; (Greer, SC) |
Correspondence
Address: |
CANTOR COLBURN, LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
40686246 |
Appl. No.: |
12/030317 |
Filed: |
February 13, 2008 |
Current U.S.
Class: |
415/198.1 |
Current CPC
Class: |
F01D 5/225 20130101 |
Class at
Publication: |
415/198.1 |
International
Class: |
F01D 5/02 20060101
F01D005/02 |
Claims
1. A rotating assembly for a turbomachine comprising: a central
hub; a plurality of rotating members extending radially outward
from the central hub, each of the plurality of rotating members
including: a base portion detachably mounted to the central hub; a
tip portion; a mid-span portion extending between the base portion
and the tip portion; a shroud portion positioned at one of the tip
portion and the mid-span portion, the shroud portion including a
pressure side and a suction side; and at least one hard face
interface member secured to at least one of the suction side and
the pressure side of the shroud portion, the at least one hard face
interface member being both mechanically interlocked with, and
metallurgically bonded to the shroud portion.
2. The rotating assembly according to claim 1, wherein the shroud
portion includes at least one recess formed in one of the pressure
side and suction side, the hard face interface member being
mechanically interlocked with the shroud portion in the at least
one recess.
3. The rotating assembly according to claim 2, wherein the at least
one recess includes a first recess formed in the pressure side of
the shroud portion and a second recess formed in the suction side
of the shroud portion.
4. The rotating assembly according to claim 3, wherein the at least
one hard face interface member includes a first hard face interface
member mechanically interlocked with and metallurgically bonded to
the shroud portion in the first recess and a second hard face
interface member mechanically interlocked with and metallurgically
bonded to the shroud portion in the second recess.
5. The rotating assembly according to claim 2, wherein the at least
one recess includes a base portion and a peripheral wall portion,
the base portion including a plurality of surface elements.
6. The rotating assembly according to claim 5, wherein the
plurality of surface elements are indentations formed in the base
portion.
7. The rotating assembly according to claim 5, wherein the
plurality of surface elements comprise at least one of a plurality
of continuous grooves, a plurality of discontinuous grooves, a
plurality of continuous protuberances and a plurality of
discontinuous protuberances.
8. The rotating assembly according to claim 1, wherein the shroud
portion is mounted to the mid-span portion of each of the plurality
of rotating members.
9. The rotating assembly according to claim 1, wherein the shroud
portion is mounted to the tip portion of each of the plurality of
rotating members.
10. The rotating assembly according to claim 1, wherein the shroud
portion is mounted to both the mid-span portion and the tip portion
of each of the plurality of rotating members.
11. The rotating assembly according to claim 1, wherein the hard
face interface member is formed from a pre-sintered preformed
material.
12. The rotating assembly according to claim 1, wherein the
rotating assembly is mounted in a turbine engine.
13. A method of securing a hard face interface member to a shroud
portion of a rotating member for a turbomachine, the method
comprising: forming a rotating member including a base portion, a
mid-span portion and a tip portion; forming a shroud portion on at
least one of the mid-span portion and the tip portion of the
rotating member, the shroud portion including a pressure side and a
suction side; and securing a hard face interface member to at least
one of the pressure side and the suction side of the shroud
portion, the hard face interface member being both mechanically
interlocked with, and metallurgically bonded to, the shroud
portion.
14. The method of claim 13, further comprising: forming at least
one recess in the one of the pressure side and the suction side of
the shroud portion; and securing the hard face interface member to
the shroud portion at the recess.
15. The method of claim 13, further comprising: brazing the hard
face interface member in the recess formed in the one of the
pressure side and the suction side of the shroud portion to secure
the hard face interface member to the shroud portion.
16. The method of claim 15, further comprising: machining the hard
face interface member to establish a final finish.
17. The method of claim 13, further comprising: forming a plurality
of indentations within the recess formed in the one of the pressure
side and the suction side of the shroud portion, the indentations
providing additional surface area in the recess to strengthen the
mechanical interlock.
18. The method of claim 13, further comprising: forming a first
recess in the pressure side of the shroud portion and a second
recess in the suction side of the shroud portion; and securing a
first hard face interface member to the shroud portion at the first
recess and a second hard face interface member at the second
recess.
19. The method of claim 13, further comprising: forming a first
shroud portion on the mid-span portion of the rotating member and a
second shroud portion on the tip portion of the rotating member;
and securing a hard face interface member to each of the first and
second shroud portions with both a mechanical interlock and a
metallurgical bond.
20. The method of claim 13, further comprising: mounting the
rotating member in a turbine-engine.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to the art of turbomachines
and, more particularly, to a rotating assembly for a
turbomachine.
[0002] Turbomachines employ a number of rotating components or
assemblies. Turbines, for example, employ compressor stages and
turbine stages that rotate at high speed when the turbine is in
operation. In general, a stage includes a plurality of
free-floating blades that extend radially outward from a central
hub. Some blades include a shroud that limits vibration within a
stage. The shroud is typically positioned at a tip portion of the
blade, a mid portion of the blade or at both the mid portion and
the tip portion of the blade. The shrouds are designed such that at
high or operational speeds, the free-floating blades interlock to
form an integral rotating member. At lower speeds, such as on
turbine turning gear, the blades do not interlock and will often
times impact one another. Impacts between the blades can cause
damage that will shorten service life of the turbomachine.
[0003] In order to minimize damage resulting from blade impacts, a
hard face coating is applied to potential contact points. The hard
face coating increases wear resistance of the potential contact
points to increase both impact resistance and durability.
Conventionally, the hard face coating is metallurgically bonded to
the blade through, for example, a welding or brazing process. Using
a welding process to bond the hard face interface to the blade
inherently produces a great deal of localized heat which, if not
properly controlled, can weaken the impact resistance and other
metallurgical properties at the interface of the materials being
joined. Excessive heat can also cause cracking in adjacent material
during manufacture. Of particular concern is maintaining integrity
in a Z-notch radius portion of the blade. The z-notch radius
portion is subjected to high stresses and therefore subject to
cracking causing a release of material. An additional failure
mechanism can occur during high speed operation when tension and/or
shear forces develop that over-stress the metallurgical bond. Over
time, the metallurgical bond can fail and the hard face coating is
released from the blade becoming foreign object debris (FOD) in the
turbomachine. FOD flying around the turbomachine can damage the
rotating components as well as inner surfaces of the turbine and
lead to engine failure.
BRIEF DESCRIPTION OF THE INVENTION
[0004] In accordance with one exemplary embodiment of the present
invention, a rotating assembly for a turbomachine includes a
central hub and a plurality of rotating members that extend
radially outward from a central hub. Each of the plurality of
rotating members includes a base portion detachably mounted to the
central hub, a tip portion, and a mid-span portion that extends
between the base portion and the tip portion. Each of the plurality
of rotating members also includes a shroud portion that is
positioned at one of the tip portion and the mid-span portion. The
shroud portion includes a pressure side and a suction side. At
least one hard face interface member is secured to at least one of
the suction side and the pressure side of the shroud portion. The
at least one hard face interface member is both mechanically
interlocked with, and metallurgically bonded to, the shroud
portion.
[0005] In accordance with another exemplary embodiment of the
present invention, a method of securing a hard face interface
member to a shroud portion of a rotating member for a turbomachine
includes forming a rotating member having a base portion, a
mid-span portion and a tip portion. A shroud portion is formed on
at least one of the mid-span portion and the tip portion of the
rotating member. The shroud portion includes a pressure side and a
suction side. A hard face interface member is secured with both a
mechanical interlock and a metallurgical bond to at least one of
the pressure side and the suction side of the shroud portion.
[0006] Additional objects, features and advantages of various
aspects of exemplary embodiments of the present invention will
become more readily apparent from the following detailed
description when taken in conjunction with the drawings wherein
like reference numerals refer to corresponding parts in the several
views.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a partial, cross-sectional schematic illustration
of a turbomachine including a rotating assembly constructed in
accordance with an exemplary embodiment of the present
invention;
[0008] FIG. 2 is a partial perspective view of a rotating assembly
including a plurality of rotating components constructed in
accordance with an exemplary embodiment of the present
invention;
[0009] FIG. 3 is a perspective view of a rotating component of FIG.
2 including a tip shroud and a mid-span shroud;
[0010] FIG. 4 is a partial side view of a suction side of the tip
shroud of FIG. 3 illustrating a hard face interface member mounted
within a cavity formed in the tip shroud in accordance with an
exemplary embodiment of the present invention;
[0011] FIG. 5 is a partial bottom view of the suction side of the
tip shroud illustrated in FIG. 4 showing a plurality of dimples
formed in the cavity for mechanically interlocking the hard face
interface member;
[0012] FIG. 6 is a partial side view of a pressure side of the tip
shroud of FIG. 3 illustrating a hard face interface member received
within a cavity formed in the tip shroud in accordance with an
exemplary embodiment of the present invention;
[0013] FIG. 7 is a partial bottom view of the pressure side of the
tip shroud illustrated in FIG. 6 showing a plurality of dimples
formed in the cavity for mechanically interlocking the hard face
interface member;
[0014] FIG. 8 is a partial bottom view of the suction side of the
tip shroud illustrated in FIG. 5 showing a plurality of continuous
protuberances provided in the cavity for mechanically interlocking
the hard face interface member;
[0015] FIG. 9 is a partial bottom view of the suction side of the
tip shroud illustrated in FIG. 5 showing a plurality of continuous
grooves formed in the cavity for mechanically interlocking the hard
face interface member;
[0016] FIG. 10 is a partial bottom view of the suction side of the
tip shroud illustrated in FIG. 5 showing a plurality of
discontinuous grooves provided in the cavity for mechanically
interlocking the hard face interface member;
[0017] FIG. 11 is a partial bottom view of the suction side of the
tip shroud illustrated in FIG. 5 showing a plurality of
discontinuous protuberances formed in the cavity for mechanically
interlocking the hard face interface member;
[0018] FIG. 12 is a detail view of a suction side of the tip shroud
of FIG. 4 illustrating a cavity having a plurality of continuous
protuberances for mechanically interlocking the hard face interface
member in accordance with another exemplary embodiment of the
present invention;
[0019] FIG. 13 is a detail view of a suction side of the tip shroud
of FIG. 4 illustrating a cavity having a plurality of discontinuous
protuberances for mechanically interlocking the hard face interface
member in accordance with yet another exemplary embodiment of the
present invention;
[0020] FIG. 14 is a detail view of a suction side of the tip shroud
of FIG. 4 illustrating a cavity having a plurality of continuous
grooves for mechanically interlocking the hard face interface
member in accordance with still another exemplary embodiment of the
present invention; and
[0021] FIG. 15 is a detail view of a suction side of the tip shroud
of FIG. 4 illustrating a cavity having a plurality of discontinuous
grooves for mechanically interlocking the hard face interface
member in accordance with a still further exemplary embodiment of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] With initial reference to FIGS. 1 and 2 a turbomachine,
shown in the form of a gas turbine engine, constructed in
accordance with an exemplary embodiment of the present invention is
indicated generally at 2. Engine 2 includes a compressor 4 and a
plurality of combustor assemblies arranged in a can annular array,
one of which is indicated at 8. As shown, combustor assembly 8
includes an endcover assembly 9 that seals, and at least partially
defines, a combustion chamber 12. A plurality of nozzles 14-16 are
supported by endcover assembly 9 and extend into combustion chamber
12. Nozzles 14-16 receive fuel through a common fuel inlet (not
shown) and compressed air from compressor 4. The fuel and
compressed air are passed into combustion chamber 12 and ignited to
form a high temperature, high pressure combustion product or air
stream that is used to drive a turbine 30. Turbine 30 includes a
plurality of rotating assemblies or stages 31-33 that are
operationally connected to compressor 4 through a
compressor/turbine shaft 34 (sometimes referred to as a rotor).
[0023] In operation, air flows into compressor 4 and is compressed
into a high pressure gas. The high pressure gas is supplied to
combustor assembly 8 and mixed with fuel, for example process gas
and/or synthetic gas (syngas), in combustion chamber 12. The
fuel/air or combustible mixture ignited to form a high pressure,
high temperature combustion gas stream of approximately 538 degrees
Celsius (.degree. C.) to 1593.degree. C. (1000 degrees Fahrenheit
(.degree. F.) to 2900.degree. F.). Alternatively, combustor
assembly 8 can combust fuels that include, but are not limited, to
natural gas and/or fuel oil. In any event, combustor assembly 8
channels the combustion gas stream to turbine 30 which coverts
thermal energy to mechanical, rotational energy.
[0024] At this point it should be understood that each rotating
assembly or stage 31-33 is similarly formed, thus reference will be
made to FIGS. 2-3 in describing stage 31 constructed in accordance
with an exemplary embodiment of the present invention with an
understanding that the remaining stages, i.e., stages 32 and 33
have corresponding structure. Also it should be understood that the
present invention could be employed in stages in compressor 4 or
other rotating assemblies that require impact resistant surfaces.
In any event, stage 31 is shown to include a plurality of rotating
members, one of which is indicated at 46, which extend radially
outward from a central hub 47. As best shown in FIG. 3, rotating
member 46 includes a base portion 48, a tip portion 49 and a
mid-span portion 50 that extends between base portion 48 and tip
portion 49. In the exemplary embodiment shown, rotating member 46
includes a first or mid-span shroud 60 having a first or suction
side 63 and a second or pressure side 64. Rotating member 46 is
also shown to include a second or tip shroud 70 having a first or
suction side 72 and a second or pressure side 73. In addition, tip
shroud 70 includes first and second opposing wing members 78 and 79
and a third wing member 80. Third wing member 80 extends
perpendicularly relative to first and second wing members 78 and
79.
[0025] Tip shroud 70 covers a bucket or throat portion (not
separately labeled) of rotating member 46. Tip shroud 70 is
designed to receive, or nest with, tip shrouds on adjacent rotating
members in order to form a continuous ring 81 that extends
circumferentially about stage 31. Continuous ring 81 creates an
outer flow path boundary that reduces gas path air leakage over top
portions (not separately labeled) of stage 31 so as to increase
stage efficiency and overall turbine performance. In a similar
manner, mid-span shroud 60 is configured to receive, or nest
within, mid-span shrouds on adjacent rotating members to form an
inner ring indicated generally at 82 that further increases stage
efficiency. At this point, it should recognized that while rotating
member 46 is shown with both mid-span shroud 60 and tip-shroud 70,
each rotating member could alternatively be provided with a single
shroud positioned either at tip portion 49 or mid-span portion 50.
In the exemplary embodiment shown, during high or operational
speeds, adjacent rotating members 46 interlock through mid-span
shroud 60 and tip-shroud 70 by virtue of centrifugal forces created
by the operation of turbine 30. However, during lower speeds such
as, during turbine turning gear, the rotational force is not
sufficient to establish the interlock and thus, often times
adjacent rotating members impact one another. The impacts can
create wear on the rotating members thereby lowering an overall
service life of turbine 30. Towards that end, each mid-span shroud
60 and tip-shroud 70 is provided with a wear resistant/impact
resistant member in a manner that will be described more fully
below.
[0026] Reference will now be made to FIGS. 4 and 5 in describing
suction side 72 of tip shroud 70. As shown, suction side 72
includes a first surface 90 and an opposing second surface 91.
Second surface 91 includes a recess or cavity 94 having a base
portion 96 and a peripheral wall portion 98. With this
configuration, a hard face interface member 100, that in accordance
with an exemplary embodiment of the present invention is formed
from a pre-sintered, preformed (PSP) material, is positioned within
cavity 94.
[0027] Hard face interface member 100 is mechanically interlocked
with, and metallurgically bonded to, suction side 72 to provide an
impact and wear resistant surface for tip shroud 70. In accordance
with one aspect of the invention, hard face interface member 100 is
positioned within cavity 94 and brazed to tip shroud 70. In this
manner, cavity 94 provides a mechanical interlock, and brazing
provides a metallurgical bond to tip shroud 70. The mechanical
interlock at an outer radial position or z-notch radius portion of
hard face interface member 100 establishes a secondary bond that
resists compressive or tensile (depending of the relative position
on tip-shroud 70) forces developed during the operation of stage
31. The mechanical interlock supplements the metallurgical bond
provided by brazing in order to create a more robust load path to
establish a fail-safe attachment/retention mechanism for hard face
interface member 100. In accordance with another aspect of the
present invention, cavity 94 is provided with a plurality of
surface elements, which, in the exemplary embodiment shown, take
the form of dimples or indentations 105 formed on a base portion
96. Indentations 105 increase an overall surface area of cavity 94
so as to establish a more robust mechanical interlock for hard face
interface member 100. In any event, after being mechanically
interlocked with, and metallurgically bonded to tip shroud 70, hard
face interface member 100 is machined so as to be substantially
flush with second surface 91 to provide an overall finish for
tip-shroud 70 that reduces localized airflow turbulences.
[0028] Reference will now be made to FIGS. 6 and 7 in describing
pressure side 73 of tip shroud 70. In a manner similar to that
described above, pressure side 73 includes a first surface 110 and
an opposing second surface 111. Second surface 111 includes a
recess or cavity 114 having a base portion 116 and a peripheral
wall portion 118. A hard face interface member 120 is positioned
within cavity 114. Hard face interface member 120, in accordance
with an exemplary embodiment of the present invention, is formed
from a PSP material and is mechanically interlocked with, and
metallurgically bonded to, pressure side 73 to provide another
impact and wear resistant surface for tip shroud 70. In a manner
also similar to that described above, hard face interface member
120 is positioned within cavity 114 and brazed to tip shroud 70 to
establish a metallurgical bond. In this manner, cavity 114 provides
a mechanical interlock, and brazing provides a metallurgical bond
to tip shroud 70. Recess 114 also includes a plurality of surface
elements, which in the exemplary embodiment shown, take the form of
dimples or indentions 124 formed on base portion 116. Indentations
124 increase an overall surface area of base portion 116 to
increase the overall strength of the mechanical interlock. In any
event, after being mechanically linked to, and metallurgically
bonded with tip shroud 70, hard face interface member 120 is
machined so as to the substantially flush with second surface 111
to provide an overall finish for tip-shroud 70 that reduces
localized airflow turbulences.
[0029] At this point, it should also be understood that mid-span
shroud 60 includes a first hard face interface member 130
positioned within a recess (not separately labeled) formed on
suction side 63 and a second hard face interface member 140
provided within a recess (not separately labeled) provided on
pressure side 64. With this arrangement, hard face interface
members 100, 120, 130 and 140 provide localized wear/impact
resistant surface enhancements that remain secured to rotating
member 46 during the operation of stage 31. That is, the
combination of the mechanical link or interlock and the
metallurgical bond provides a fail-safe multiple-load path,
attachment/retention mechanism that is resistant to multiple
directional loading for hard face interface member 100. Moreover,
the addition of the mechanical interlock provides a bond that makes
up for any diminished metallurgical properties (most notable of
which is impact resistance) of rotating member 46 created through
the application of heat established during brazing. It should be
understood that in addition to dimples or indentations, various
other surface elements can be employed to enhance bonding between
the hard face interface member and the blade. For example, FIG. 8
illustrates a plurality of continuous protuberances 200 arranged on
base portion 96. FIG. 9 illustrates a plurality of continuous
grooves 210 formed in base portion 96. FIG. 10 depicts base portion
96 with a plurality of discontinuous grooves 220 while FIG. 11
shows base portion 96 with a plurality of discontinuous or
segmented protuberances 230. In any case, it should be apparent
that various elements can be employed to enhance the mechanical
bond between the hard face interface member and the blade.
[0030] Moreover, in addition to cavities 94 and 114, Tip and/or mid
span shroud 70 and 60 can include a machined cavity or recess 300
having a radius portion 310 and a plurality of continuous
protuberances 320 such as shown in FIG. 12. Recess 300 is formed by
removing for example, approximately 1/10'' (2.54 mm) of a face
portion of suction side 72. FIG. 13 illustrates a cavity or recess
360 having a radius portion 370 formed on a face portion of suction
side 72. Recess 360 includes a plurality of discontinuous
protuberances 380 for mechanically interlocking a hard face
interface member. FIG. 14 illustrates a cavity or recess 400 having
a radius portion 410 formed in suction side 72. Recess 400 includes
a plurality of continuous grooves 420 for mechanically interlocking
the hard face interface member. Finally, FIG. 15 illustrates a
cavity or recess 460 having a radius 470 formed in suction side 72.
Recess 460 includes a plurality of discontinuous grooves 480 for
mechanically interlocking the hard face interface member. Of
course, it should be understood, that the particular hard face
interface member would include structure corresponding to the
protuberances or grooves to facilitate the mechanical
interlock.
[0031] In general, this written description uses examples to
disclose the invention, including the best mode, and also to enable
any person skilled in the art to practice the invention, including
making and using any devices or systems and performing any
incorporated methods. The patentable scope of the invention is
defined by the claims, and may be includes other examples that
occur to those skilled in the art. Such other examples are intended
to be within the scope of the present invention if they have
structural elements that do not differ from the literal language of
the claims, or if they include equivalent structural elements with
insubstantial differences from the literal language of the
claims.
* * * * *