U.S. patent application number 14/865015 was filed with the patent office on 2017-03-30 for identifying bucket deformation in turbomachinery.
The applicant listed for this patent is General Electric Company. Invention is credited to Yan Cui, Ganjiang Feng, Srikanth Chandrudu Kottilingam, Dechao Lin, Brian Lee Tollison.
Application Number | 20170089216 14/865015 |
Document ID | / |
Family ID | 56979437 |
Filed Date | 2017-03-30 |
United States Patent
Application |
20170089216 |
Kind Code |
A1 |
Cui; Yan ; et al. |
March 30, 2017 |
IDENTIFYING BUCKET DEFORMATION IN TURBOMACHINERY
Abstract
Embodiments of the present disclosure provide turbine buckets,
turbomachinery, and related methods for identifying bucket
deformation. A turbine bucket according to embodiments of the
present disclosure can include an airfoil extending radially from a
base, relative to a rotor axis of a turbomachine; and a magnetized
material coupled to the airfoil proximal to a radially outer end
thereof. To identify bucket deformation, a magnetic sensor can
measure a magnetic field strength of the magnetized material, and a
computing device in communication with the magnetic sensor can
identify the turbine bucket as being one of deformed and
non-deformed based on the magnetic field strength of the magnetized
material.
Inventors: |
Cui; Yan; (Greer, SC)
; Feng; Ganjiang; (Simpsonville, SC) ;
Kottilingam; Srikanth Chandrudu; (Simpsonville, SC) ;
Lin; Dechao; (Greer, SC) ; Tollison; Brian Lee;
(Honea Path, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
56979437 |
Appl. No.: |
14/865015 |
Filed: |
September 25, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01D 5/147 20130101;
Y02T 50/60 20130101; F01D 17/02 20130101; F01D 5/12 20130101; Y02T
50/673 20130101; F05D 2260/80 20130101; F01D 21/003 20130101 |
International
Class: |
F01D 21/00 20060101
F01D021/00; F01D 5/12 20060101 F01D005/12 |
Claims
1. A turbine bucket comprising: an airfoil extending radially from
a base, relative to a rotor axis of a turbomachine; and a
magnetized material coupled to the airfoil and proximal to a
radially outer end thereof.
2. The turbine bucket of claim 1, wherein the magnetized material
comprises a magnetic braze alloy joined to the airfoil via one of a
vacuum braze and a weld.
3. The turbine bucket of claim 1, wherein the airfoil further
includes a recess therein, wherein the magnetized material is
housed within the recess.
4. The turbine bucket of claim 3, wherein a surface of the
magnetized material is substantially planar with an outer surface
of the airfoil.
5. The turbine bucket of claim 1, further comprising: a magnetic
sensor configured to measure a magnetic field strength of the
magnetized material; and a computing device in communication with
the magnetic sensor, wherein the computing device identifies the
turbine bucket as being one of deformed and non-deformed based on
the magnetic field strength of the magnetized material.
6. The turbine bucket of claim 5, wherein the computing device is
further configured to calculate a length of the turbine bucket
based on the magnetic field strength of the magnetized
material.
7. The turbine bucket of claim 5, further comprising a shroud
radially distal to the airfoil, wherein the magnetic sensor is
coupled to the shroud.
8. A turbomachine comprising: a rotor wheel coupled to a rotor; a
turbine bucket including: a base mechanically coupled to the rotor
wheel, an airfoil extending radially from the base, relative to a
rotor axis of the turbomachine, wherein the airfoil includes a
bucket tip proximal to a radially outer end thereof, and a
magnetized material coupled to the bucket tip; a stationary
component radially distal to the bucket tip; and a magnetic sensor
coupled to the stationary component, wherein the magnetic sensor
measures a magnetic field strength of the magnetized material.
9. The turbomachine of claim 8, further comprising a computing
device in communication with the magnetic sensor, wherein the
computing device identifies the turbine bucket as being one of
deformed and non-deformed based on the magnetic field strength of
the magnetized material.
10. The turbomachine of claim 8, wherein the turbomachine comprises
a gas turbine, and wherein the turbine bucket is positioned within
a hot gas path (HGP) section of the gas turbine.
11. The turbomachine of claim 8, wherein the computing device is
further configured to calculate the length of the turbine bucket
based on the magnetic field strength of the magnetized
material.
12. The turbomachine of claim 8, wherein the magnetized material
comprises a magnetic braze alloy joined to the bucket tip via one
of a vacuum braze and a weld.
13. The turbomachine of claim 8, wherein the bucket tip further
includes a recess therein, wherein the magnetized material is
housed within the recess of the bucket tip.
14. The turbomachine of claim 13, wherein the surface of the
magnetized material is substantially planar with an outer surface
of the bucket tip.
15. A method for identifying bucket deformation in a turbomachine,
the method comprising: measuring a magnetic field strength of a
magnetized material positioned within a turbine bucket; calculating
a difference between the magnetic field strength and a reference
field strength; and identifying the turbine bucket as being one of
deformed and non-deformed based on the calculated difference.
16. The method of claim 15, further comprising calculating a length
of the turbine bucket based on the magnetic field strength of the
magnetized material.
17. The method of claim 15, wherein the turbine bucket remains
coupled to a rotor wheel of the turbomachine during the
measuring.
18. The method of claim 15, wherein the magnetized material
comprises a magnetic braze alloy joined to the turbine bucket via
one of a vacuum braze and a weld.
19. The method of claim 15, further comprising, before the
measuring: calibrating a position where a magnetic field strength
of a magnetized material within a non-deformed turbine bucket is
zero; and setting the reference field strength as equal to zero at
the calibrated position, wherein the measuring of the magnetic
field strength occurs at the calibrated position.
20. The method of claim 15, further comprising, before the
measuring: forming a cavity in a bucket tip of the turbine bucket;
filling the cavity with the magnetized material; and machining a
surface of the magnetized material to be substantially planar with
an outer surface of the bucket tip.
Description
BACKGROUND
[0001] The disclosure relates generally to turbomachinery, and more
particularly, to turbine buckets and turbomachines which can be
used to identify bucket deformation. Embodiments of the present
disclosure also include methods for identifying bucket deformation
in turbomachinery.
[0002] Turbomachinery such as turbine systems can generate power
for, e.g., electric generators. A working fluid such as hot gas or
steam can flow across sets of turbine blades (generally known in
the art as "buckets") mechanically coupled to a rotor of the
turbine system. The force of the working fluid on the blades causes
those blades (and the coupled body of the rotor) to rotate. The
rotor body can be coupled to the drive shaft of a dynamoelectric
machine such as an electric generator. Initiating rotation of the
turbine rotor can also rotate the drive shaft in the electric
generator to generate an electrical current and a particular power
output.
[0003] Buckets may be subject to mechanical stress over their
lifespan and the operation of a turbomachinery system. In some
cases, stress can cause the dimensionality of a turbine bucket or
other component to change over time. In one example, a phenomenon
known as "creep" can refer to a gradual lengthening deformation of
a component when subjected to material stresses in a particular
direction over time. Turbine buckets may undergo creep and/or other
types of deformation when subject to particular operating
circumstances and/or operating times. Conventional methods for
identifying deformation, such as creep, may include removing the
turbine buckets from the structure of a turbomachine to execute a
diagnostic test.
SUMMARY
[0004] A first aspect of the disclosure provides a turbine bucket
including: an airfoil extending radially from a base, relative to a
rotor axis of a turbomachine; and a magnetized material coupled to
the airfoil proximal to a radially outer end thereof.
[0005] A second aspect of the disclosure provides a turbomachine
including: a rotor wheel coupled to a rotor; a turbine bucket
including: a base mechanically coupled to the rotor wheel, an
airfoil extending radially from the base, relative to a rotor axis
of the turbomachine, a bucket tip coupled to the airfoil, and a
magnetized material coupled to the bucket tip; a stationary
component radially distal to the bucket tip of the turbine bucket;
and a magnetic sensor coupled to the stationary component, wherein
the magnetic sensor measures a magnetic field strength of the
magnetized material.
[0006] A third aspect of the invention provides a method for
identifying bucket deformation in a turbomachine. Methods according
to the present disclosure can include: measuring a magnetic field
strength of a magnetized material positioned within a turbine
bucket; calculating a difference between the magnetic field
strength and a reference field strength; and identifying the
turbine bucket as being one of deformed and non-deformed based on
the calculated difference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features of the disclosed system will be
more readily understood from the following detailed description of
the various aspects of the system taken in conjunction with the
accompanying drawings that depict various embodiments, in
which:
[0008] FIG. 1 shows a schematic view of a turbomachine according to
embodiments of the present disclosure.
[0009] FIG. 2 is a cross-sectional view of a turbomachine according
to embodiments of the present disclosure.
[0010] FIG. 3 is a partial perspective view of a turbine bucket
according to embodiments of the present disclosure.
[0011] FIG. 4 is an illustrative plot of magnetic field strength
versus displacement from a magnetic material according to
embodiments of the present disclosure.
[0012] FIG. 5 is an illustrative environment of a computing device
operatively connected to a magnetic sensor according to embodiments
of the present disclosure.
[0013] It is noted that the drawings are not necessarily to scale.
The drawings are intended to depict only typical aspects of the
disclosure, and therefore should not be considered as limiting its
scope. In the drawings, like numbering represents like elements
between the drawings.
DETAILED DESCRIPTION
[0014] In the following description, reference is made to the
accompanying drawings that form a part thereof, and in which is
shown by way of illustration specific exemplary embodiments in
which the present teachings may be practiced. These embodiments are
described in sufficient detail to enable those skilled in the art
to practice the present teachings and it is to be understood that
other embodiments may be utilized and that changes may be made
without departing from the scope of the present teachings. The
following description is, therefore, merely illustrative.
[0015] Spatially relative terms, such as "inner," "outer,"
"underneath," "below," "lower," "above," "upper," "inlet,"
"outlet," and the like, may be used herein for ease of description
to describe one element or feature's relationship to another
element(s) or feature(s) as illustrated in the figures. Spatially
relative terms may be intended to encompass different orientations
of the device in use or operation in addition to the orientation
depicted in the figures. For example, if the device in the figures
is turned over, elements described as "below" or "underneath" other
elements or features would then be oriented "above" the other
elements or features. Thus, the example term "below" can encompass
both an orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
[0016] As indicated above, the disclosure provides a structures and
methods for identifying bucket deformation in a turbomachine. FIG.
1 shows a turbomachine 100 that includes a compressor portion 102
operatively coupled to a turbine portion 104 through a shared
compressor/turbine shaft 106. Compressor portion 102 is also
fluidically connected to turbine portion 104 through a combustor
assembly 108. Combustor assembly 108 includes one or more
combustors 110. Combustors 110 may be mounted to turbomachine 100
in a wide range of configurations including, but not limited to,
being arranged in a can-annular array. Compressor portion 102
includes a plurality of compressor rotor wheels 112. Rotor wheels
112 include a first stage compressor rotor wheel 114 having a
plurality of first stage compressor rotor blades 116 each having an
associated airfoil portion 118. Similarly, turbine portion 104
includes a plurality of turbine rotor wheels 120 including a first
stage turbine wheel 122 having a plurality of turbine buckets 124,
e.g., provided as first stage turbine rotor blades. Stationary
blades within turbine portion 104, discussed elsewhere herein, can
direct gases through turbine portion 104 against turbine buckets
124 of turbine portion 104. Although embodiments of the present
disclosure may be described as positioned within turbine portion
104, it is understood that various embodiments can optionally be
positioned in other components or areas of turbomachine 100
including, e.g., compressor portion 102. In addition, embodiments
of the present disclosure can be adapted for use in other forms of
machinery, e.g., steam turbines, water turbines, aircraft engines,
independent compressors, etc.
[0017] Referring to FIG. 2, a partial cross-sectional view of
turbine bucket 124 within turbine portion 104 of turbomachine 100
(FIG. 1) according to embodiments of the present disclosure is
shown. Turbine bucket 124 can be positioned within a flow path 140
for accommodating operating fluids such as hot combustion gases,
steam, etc., which can flow generally along the direction noted
with flow lines F. The operative fluid within flow path 140 can
reach turbine bucket(s) 124 as directed by the position and
contours of a stationary blade 150, also known in the art as a
nozzle. Turbine portion 104 is shown extending along a rotor axis Z
of turbine wheel 122 (e.g., coaxial with shaft 106 (FIG. 1)), and
with a radial axis R extending outwardly therefrom. In the case of
a gas turbine, flow path 140 with turbine bucket 124 can be a hot
gas path (HGP) adapted to transmit combusted gases as the operative
fluid, such that turbine bucket 124, stationary blade 150, and
other components discussed herein include materials adapted to
withstand temperatures of, e.g., more than approximately 1000
degrees Celsius (.degree. C.). Turbine bucket 124 can include a
group of subcomponents defined by reference to their structure and
position. A base 160 can provide a mechanical connection to shaft
106, e.g., by direct attachment to turbine wheel 122 with dovetail
protrusions and/or slots. Base 160 of each turbine bucket 124 can
thereby join turbine bucket 124 to shaft 106 (e.g., through turbine
wheel 122) during operation. Turbine bucket 124 may undergo one or
more types of deformation, e.g., expansion deformation from
mechanical creep, after being in use for several service hours. In
turbine portion 104, turbine bucket 124 may expand, e.g.,
substantially in the direction of deformation axis R. However, it
is understood that that deformation axis R may have a different
orientation and/or direction in other implementations. For
instance, it may be possible for turbine bucket(s) 124 to
additionally or alternatively deform in a rotational and/or
circumferential direction relative to shaft 106.
[0018] An airfoil 170 of turbine bucket 124 can extend outwardly
from base 160, and can be oriented substantially along (i.e.,
extending in a direction parallel with or within at most
approximately ten degrees of) radial axis R. A radially outer end
of airfoil 170 can include a bucket tip 172, e.g., including a
surface contour for further directing the flow of operating fluids
in flow path 140 against turbine bucket 124. Bucket tip 172 can be
radially proximal to a shroud 180 for defining a rotation path of
turbine bucket 124. A portion of flow path 140 can be positioned
radially between turbine bucket 124 and shroud 180. Although one
stationary blade 150 is shown in the cross-sectional view of FIG.
2, it is understood that multiple turbine buckets 124 and
stationary blades 150 can extend radially from turbine wheel 122,
e.g., extending laterally into and/or out of the plane of the page.
A length of turbine bucket 124 can be defined, e.g., as the radial
distance between a radially inner end of base 160 and a radially
outer end of bucket tip 172 as noted by line "L." However, it
should be understood that the length of turbine bucket 124 can be
alternatively defined.
[0019] Turning to FIG. 3, a partial perspective view an enlarged
tip of airfoil 170 of turbine bucket 124 is shown. A radially outer
region of airfoil 170 can be provided in the form of a bucket tip
172, e.g., having a distinct surface contour and/or structural
features. Turbine bucket 124 can include a magnetized material 200
coupled to airfoil 170, e.g., at bucket tip 172, and thereby
positioned proximal to a radially outer end of turbine bucket 124.
Although magnetized material 200 is shown in FIG. 3 as being
located within bucket tip 172, it is understood that magnetized
material 200 can additionally or alternatively be positioned at
other regions of airfoil 170. Magnetized material 200 can generally
be composed of any currently known or later developed substance
which generates a magnetic field. As specific examples, magnetized
material 200 can include one or more para-magnetic and/or
ferro-magnetic alloys, e.g., nickel-based and/or cobalt
based-alloys. Magnetized material 200 can be formed via one or more
methodologies otherwise applied to form a metallic material on
another structure, such as brazing (including, e.g., vacuum
brazing, braze welding, torch brazing, etc.), welding (including,
e.g., gas tungsten arc welding and/or other welding processes which
use an inert gas), and/or other techniques. Magnetized material
200, in an example embodiment, can include an alloy having the
chemical formula Ni.sub.19Co.sub.19Fe.sub.3B and including mass
composition percentages of, e.g., approximately 19% Cobalt (Co),
approximately 19% Iron (Fe), approximately 0.05% Aluminum (Al),
approximately 0.05% Titanium (Ti), between approximately 2.75% and
approximately 3.75% Boron (B), between approximately 6% and 13%
Chromium (Cr), and with the remainder being composed of, e.g.,
Nitrogen (N). Example materials which can form or be included with
magnetized material 200 are discussed generally in U.S. Patent
Application Publication US 2014/0227550.
[0020] In some embodiments, turbine bucket 124 can be machined to
form a recess 202 positioned, e.g., on an outer surface of airfoil
170. Recess 202 can be sized to house a corresponding amount of
magnetized material 200 therein. For example, recess 202 can be
formed by selectively removing a surface area of airfoil 170 to
define a particular volume. Magnetized material 200 can be formed
in recess 202, e.g., by way of brazing or other processes of
forming magnetized materials or other metals, e.g., deposition. To
reduce aerodynamic losses such as those arising from a contour
mismatch between the outer surface of magnetized material 200
and/or turbine bucket 124, an outer surface of magnetized material
and turbine bucket 124 can be planarized such that magnetized
material 200 is substantially planar with an outer surface profile
of turbine bucket 124. Planarizing magnetized material 200 relative
to the surface of turbine bucket 124 can substantially retain the
original surface profile of turbine bucket 124. By extension, the
aerodynamic properties of magnetized material 200 and turbine
bucket 124 within flow path 140 can be substantially identical to
those of turbine bucket(s) 124 without magnetized material 200
therein.
[0021] Referring to FIGS. 2 and 4, the magnetic field strength of
magnetized material 200 (measured, e.g., in Gauss (G)) can decay
relative to the separation distance ("distance," measured, e.g., in
millimeters (mm)) between magnetized material 200 and a magnetic
sensor 204. As turbine bucket 124 undergoes a length deformation,
the location of magnetized material 200 therein relative to
magnetic sensor 204 changes. As a result, deformation of turbine
bucket 124 can affect the magnetic field strength measured with
magnetic sensor 204 at a fixed position. Example embodiments of
magnetic sensor 204 are described in detail elsewhere herein. In
the example of FIG. 4, the magnetic field strength can be, e.g.,
approximately 67 Gauss at a separation distance of approximately 12
mm between magnetized material 200 and magnetic sensor 204, but can
decay exponentially to approximately zero at a separation distance
of approximately 75 mm. The sensitivity of magnetic field strength
relative to distance can vary based on the material composition,
volume, etc., of magnetized material 200 and/or the type of
magnetic sensor 204. During operation of the structures discussed
herein and/or implementation of methods for identifying bucket
deformation, the magnetic field strength of magnetized material 200
as measured in a fixed reference position can indicate a change in
the dimensionality of turbine bucket 124. These changes in
dimensionality may stem from, e.g., heat transfer to turbine bucket
124 and/or mechanical wear such as stress, strain, creep, etc.,
experienced by turbine bucket 124 during operation of turbomachine
100 (FIG. 1).
[0022] Further components can be provided with turbine bucket 124
to identify deformation thereof over the operating period of
turbomachine 100 (FIG. 1). Specifically, a magnetic sensor 204 can
be affixed or otherwise coupled to a component of turbomachine 100
at a fixed position thereof, e.g., a radially inner surface of
shroud 180 and/or other component radially distal to turbine bucket
124. Magnetic sensor 204 can be embodied as one or more instruments
for measuring the magnetic field strength at a particular location,
e.g., a DC gaussmeter, a magnetometer, an AC/DC detector, a
polarity checker, a probe, a hall effect sensor, a field-viewing
instrument such as a viewer gel or filing viewer, etc. A computing
device 206 can be in communication with magnetic sensor 204, e.g.,
by way of any currently known or later-developed wired or wireless
connection capable of transmitting signals. Computing device 206
can include hardware and/or software for receiving and/or deriving
magnetic field strengths of magnetized material 200 detected with
magnetic sensor 204, and/or identifying turbine bucket 124 as being
deformed or non-deformed based on the values of magnetic field
strength received from magnetic sensor 204. Computing device 206 in
addition or alternatively can calculate a length dimension of
turbine bucket 124 (e.g., length "L"). As is discussed in further
detail elsewhere herein, computing device 206 can indirectly
calculate the length of turbine bucket 124 based on the magnetic
field strength measured with magnetic sensor 204, using, e.g., a
look-up table, algorithm, etc., by reference to an initial or
non-deformed length of turbine bucket 124.
[0023] FIG. 5 depicts an illustrative environment 300 where
computing device 206 is placed in communication with one or more
magnetic sensors 204 according to embodiments. To this extent,
environment 300 includes computing device 206 for identifying
deformation of turbine bucket(s) 124 (FIGS. 1-3) and/or determining
a degree of deformation (e.g., difference(s) in length). Although
one magnetic sensor 204 is shown in FIG. 5, it is understood that
environment 300 with computing device 206 can be used with multiple
magnetic sensors 204, each of which may be configured to measure
magnetic field strengths relative to magnetized material 200 (FIGS.
2, 3) in one turbine bucket 124 and/or respective turbine buckets
124.
[0024] Computing device 206 is shown including a processing
component 304 (e.g., one or more processors), a memory 306 (e.g., a
storage hierarchy), an input/output (I/O) component 308, an I/O
device 309 (e.g., one or more I/O interfaces and/or devices), and a
communications pathway 310. In general, processing component 304
executes program code, such as a deformation analysis system 312 at
least partially fixed in memory 306. While executing program code,
processing component 304 can process data, which can result in
reading and/or writing transformed data from/to memory 306 and/or
I/O device 309 for further processing. Pathway 310 provides a
communications link between each of the components in computing
device 206. I/O component 308 can comprise one or more human I/O
devices, which enable a human or system user 316 to interact with
computing device 206 and/or one or more communications devices to
enable user(s) 316 to communicate with computing device 206 using
any type of communications link. To this extent, deformation
analysis system 312 can manage a set of interfaces (e.g., graphical
user interface(s), application program interface, etc.) that enable
user(s) 316 to interact with deformation analysis system 312.
Further, deformation analysis system 312 can manage (e.g., store,
retrieve, create, manipulate, organize, present, etc.) data, such
as system data 318 (including measured magnetic field strengths,
calculated bucket lengths, etc.) using any solution.
[0025] Computing device 206 can comprise one or more
general-purpose or specific-purpose computing articles of
manufacture (e.g., computing devices) capable of executing program
code, such as deformation analysis system 312 installed thereon. As
used herein, it is understood that "program code" means any
collection of instructions, in any language, code or notation, that
cause a computing device having an information processing
capability to perform a particular function either directly or
after any combination of the following: (a) conversion to another
language, code or notation; (b) reproduction in a different
material form; and/or (c) decompression. To this extent,
deformation analysis system 312 can be embodied as any combination
of system software and/or application software.
[0026] Further, deformation analysis system 312 can be implemented
using a set of modules, e.g., a calculator 320, a comparator 322,
and a determinator 324. In this case, each module can enable
computing device 206 to perform a set of tasks used by deformation
analysis system 312, and can be separately developed and/or
implemented apart from other portions of deformation analysis
system 312. One or more modules of memory 306 can display (e.g.,
via graphics, text, sounds, and/or combinations thereof) a
particular user interface on a display component such as a monitor.
When fixed in memory 306 of computing device 206 that includes
processing component 304, each module can be module a substantial
portion of a component that implements the functionality.
Regardless, it is understood that two or more components, modules
and/or systems may share some/all of their respective hardware
and/or software. Further, it is understood that some of the
functionality discussed herein may not be implemented or additional
functionality may be included as part of computing device 206.
[0027] When computing device 206 comprises multiple computing
devices, each computing device may have only a portion of
deformation analysis system 312 (e.g., one or more modules)
thereon. However, it is understood that computing device 206 and
deformation analysis system 312 are only representative of various
possible equivalent computer systems that may perform a process
described herein. To this extent, in other embodiments, the
functionality provided by computing device 206 and deformation
analysis system 312 can be at least partially implemented by one or
more computing devices that include any combination of general
and/or specific purpose hardware with or without program code. In
each embodiment, the hardware and program code, if included, can be
created using standard engineering and programming techniques,
respectively.
[0028] Regardless, when computing device 206 includes multiple
computing devices, the computing devices can communicate over any
type of communications link. Further, while performing a process
described herein, computing device 206 can communicate with one or
more other computer systems using any type of communications link.
In either case, the communications link can comprise any
combination of various types of wired and/or wireless links;
comprise any combination of one or more types of networks; and/or
use any combination of various types of transmission techniques and
protocols.
[0029] Referring to FIGS. 2 and 5 together, embodiments of the
present disclosure can provide methods for identifying bucket
deformation in a turbomachine. Methods according to the present
disclosure can be implemented by way of, e.g., the various
structures and components described herein. In particular, methods
according to the present disclosure can be implemented as an
in-situ process without the components of turbomachine 100, turbine
portion 104, and/or turbine bucket 124 being disassembled and/or
reconstructed. It is also understood that one or more of the
components discussed herein can remain in place during operation of
turbomachine 100. As a result, turbine bucket 124, magnetized
material 200, magnetic sensor 204, etc., can remain in place within
turbomachine 100 as one or more of the various steps described
herein are implemented.
[0030] Methods according to the present disclosure can include
measuring a magnetic field strength of magnetized material 200
positioned within turbine bucket 124, e.g., using magnetic
sensor(s) 204. The magnetic field strength of magnetized material
200 can be measured at a stationary reference position, which may
be calibrated as part of the same method and/or a different
calibration process. For instance, methods according to the present
disclosure can include calibrating a position, e.g., within turbine
portion 104, where magnetic sensor 204 indicates a magnetic field
strength of magnetized material 200 being zero. The calibrated
position, in particular, can be located on or proximal to an axis
of material deformation of turbine bucket 124 (e.g., substantially
parallel with radial axis R), and can be separated from a radially
outer end of turbine bucket 124 by a predetermined distance (e.g.,
100 mm) such that magnetic sensor(s) 204 is responsive to changes
in the length of turbine bucket 124. In addition or alternatively,
a portion of magnetic sensor 204 can include a "zero gauss chamber"
configured for use with a geomagnetometer to provide a zero gauss
reference value to counteract ambient magnetic fields and thereby
aid the calibration of magnetic sensor 204. In some instances, the
calibration process can performed using a reference turbine bucket
124, without significant deformation, on turbine wheel 122 before
reinstalling the inspected turbine bucket 124. The installation
and/or replacement of turbine bucket 124 can be performed as part
of a separate maintenance process, and/or can be an additional step
performed during testing, maintenance, inspection, etc. In other
embodiments, magnetic sensor 204 can be calibrated at the time of
manufacture using turbine bucket 124 in an initial state.
Regardless of the calibration technique implemented, computing
device 206 and/or user 316 can define a "reference field strength"
at the position where magnetic sensor(s) 204 is placed and/or
calibrated. The reference field strength can be stored, e.g., in
memory 306 as system data 318. The reference field strength can
indicate an initial magnetic field strength of magnetized material
200 from turbine bucket(s) 124, and/or a magnetic field strength of
magnetized material 200 in turbine buckets 124 without significant
deformation.
[0031] To identify the presence of absence of deformation in
turbine bucket(s) 124, calculator 320 of deformation analysis
system 312 can calculate a difference between a magnetic field
strength measured with magnetic sensor(s) 204 and the reference
field strength. Thereafter, comparator 322 can compare the
calculated difference with a threshold difference indicative of
deformation in turbine bucket 124. In an example embodiment, the
threshold difference can be a change in magnetic field strength of
at least approximately 50 G. Alternatively, the threshold
difference can be a different amount of magnetic field increase
and/or decrease, e.g., 5 G, 500 G, 5 Teslas (T), 50 T, etc. Where
the threshold difference is not exceeded, determinator 324 of
deformation analysis system 312 can identify turbine bucket 124 as
being non-deformed. Where the threshold difference is exceeded,
determinator 324 of deformation analysis system 312 can identify
turbine bucket 124 as being deformed. It is to be understood that
the criteria applied to identify turbine bucket 124 as being
deformed or non-deformed (e.g., the threshold difference in
magnetic field strength) may be identical to or different from
external inspection requirements, margins of error, etc. As such,
turbine buckets 124 identified as being "deformed" may not be
considered "deformed" in a colloquial sense or under different
deformation criteria for turbine bucket 124.
[0032] Methods of the present disclosure, optionally, can also
determine a length of turbine bucket 124 based on the calculated
magnetic field strength and/or difference in magnetic field
strength relative to the reference magnetic field strength. For
example, system data 318 can include a measured or predicted
relationship between magnetic field strength and a separation
distance between magnetic sensor 204 and turbine bucket 124, such
as that depicted in FIG. 4. In this case, calculator 320 can
calculate a length of turbine bucket 124, e.g., by an inferential
and/or statistical analysis by direct calculations, look-up tables,
algorithms for derivation, and/or combinations thereof. In an
example embodiment, a magnetic field strength of 50 G may correlate
to a change in separation distance of approximately 20 mm. In this
example, calculator 320 can add 20 mm to the original or reference
length of turbine bucket 124 to yield the length of turbine bucket
124.
[0033] Methods according to the present disclosure can also include
processes for modifying turbomachine 100 to provide one or more
components described herein and/or to implement other method steps.
For example turbine bucket 124 can be modified before measuring and
analyzing turbine bucket(s) 124 with magnetic sensor(s) 204.
Methods according to the present disclosure can therefore include
forming recess 202 within airfoil 170 of turbine bucket 124, e.g.,
at bucket tip 172 thereof. Recess 202 can then be filled with
magnetized material 200, e.g., by way of a brazing process adapted
to form one or more magnetized metals, alloys, etc., therein. To
substantially maintain the original aerodynamic properties of
turbine bucket 124, magnetized material 200 and/or an outer surface
of turbine bucket 124 can be machined (e.g., polished, cut,
burnished, etc.) to be substantially planar with each other and
thereby yield a smoothed surface profile with a reduced surface
roughness.
[0034] It is understood that aspects of the invention further
provide various alternative embodiments. For example, embodiments
of the present disclosure can include manual use of computing
device 206 (e.g., operation by a technician) and/or automated use
by the intervention of one or more computer systems operatively
connected thereto to provide, e.g., one or more of the various
effects discussed herein. It is thus understood that computing
device 206 may serve technical purposes in other settings beyond
general operation, including without limitation: inspection,
maintenance, repair, replacement, testing, etc.
[0035] Deformation analysis system 312 can be provided in the form
of a computer program fixed in at least one computer-readable
medium, which when executed, enables computing device 206 to
identify and/or measure deformation in turbine bucket(s) 124. To
this extent, the computer-readable medium includes program code
which implements some or all of the processes and/or embodiments
described herein. It is understood that the term "computer-readable
medium" comprises one or more of any type of tangible medium of
expression, now known or later developed, from which a copy of the
program code can be perceived, reproduced or otherwise communicated
by a computing device. For example, the computer-readable medium
can comprise: one or more portable storage articles of manufacture;
one or more memory/storage components of a computing device; paper;
etc.
[0036] Embodiments of the present disclosure can provide several
technical and commercial advantages, some of which are discussed by
way of example herein. For instance, embodiments of the present
disclosure can provide a turbine bucket, testing device, and/or kit
for measuring and identifying material deformation in components of
a turbomachine during its service life. In addition, embodiments of
the present disclosure can be included with newly manufactured
turbomachines and/or added to existing turbomachines, and can
remain in place during operation as part of a larger power
generation system or network of power generation devices.
Embodiments of the present disclosure can also provide an in-situ
methodology for repeated monitoring of components without a partial
or complete disassembly of a turbine portion and/or
turbomachine.
[0037] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the disclosure. As used herein, the singular forms "a," "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0038] This written description uses examples to disclose the
invention, including the best mode, and 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 include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims 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.
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