U.S. patent application number 13/343301 was filed with the patent office on 2013-07-04 for turbine assembly and method for reducing fluid flow between turbine components.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is Shadab Ali, Mohankumar Banakar, Mahesh Pasupuleti, Viswanathan Venkatachalapathy. Invention is credited to Shadab Ali, Mohankumar Banakar, Mahesh Pasupuleti, Viswanathan Venkatachalapathy.
Application Number | 20130170944 13/343301 |
Document ID | / |
Family ID | 47665822 |
Filed Date | 2013-07-04 |
United States Patent
Application |
20130170944 |
Kind Code |
A1 |
Pasupuleti; Mahesh ; et
al. |
July 4, 2013 |
TURBINE ASSEMBLY AND METHOD FOR REDUCING FLUID FLOW BETWEEN TURBINE
COMPONENTS
Abstract
According to one aspect of the invention, a turbine assembly
includes a first bucket with a first slashface and a second bucket
including a recess formed in a second slashface of the second
bucket, wherein the second slashface is adjacent to the first
slashface when the first bucket is positioned adjacent to the
second bucket. The turbine assembly also includes a pin configured
to be placed in the recess, wherein the pin is magnetically urged
toward the first slashface to reduce fluid flow between the first
and second buckets.
Inventors: |
Pasupuleti; Mahesh;
(Bangalore, IN) ; Ali; Shadab; (Bangalore, IN)
; Banakar; Mohankumar; (Bangalore, IN) ;
Venkatachalapathy; Viswanathan; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pasupuleti; Mahesh
Ali; Shadab
Banakar; Mohankumar
Venkatachalapathy; Viswanathan |
Bangalore
Bangalore
Bangalore
Bangalore |
|
IN
IN
IN
IN |
|
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
47665822 |
Appl. No.: |
13/343301 |
Filed: |
January 4, 2012 |
Current U.S.
Class: |
415/1 ;
415/171.1 |
Current CPC
Class: |
F05D 2240/55 20130101;
F01D 11/006 20130101; F05D 2260/32 20130101; F05D 2300/507
20130101 |
Class at
Publication: |
415/1 ;
415/171.1 |
International
Class: |
F04D 29/08 20060101
F04D029/08 |
Claims
1. A turbine assembly comprising: a first bucket with a first
slashface, a second bucket including a recess formed in a second
slashface of the second bucket, wherein the second slashface is
adjacent to the first slashface when the first bucket is positioned
adjacent to the second bucket; and a pin configured to be placed in
the recess, wherein the pin is magnetically urged toward the first
slashface to reduce fluid flow between the first and second
buckets.
2. The turbine assembly of claim 1, wherein the recess is in a
shank of the second bucket.
3. The turbine assembly of claim 1, wherein the pin is magnetically
urged by a magnetic layer on the pin.
4. The turbine assembly of claim 3, wherein the magnetic layer is
applied to the pin by a spray.
5. The turbine assembly of claim 1, wherein first slashface has a
magnetic property to urge the pin toward the first slashface.
6. The turbine assembly of claim 5, wherein the magnetic property
of the first slashface is caused by a magnetic layer in the first
slashface.
7. The turbine assembly of claim 6, wherein the magnetic layer is
applied by a spray.
8. The turbine assembly of claim 1, wherein the pin is oriented in
a substantially radial direction and urged in a substantially
tangential direction.
9. The turbine assembly of claim 1, comprising two pins placed in
two recesses in the second slashface to reduce fluid flow between
the first and second buckets.
10. A method for reducing fluid flow between turbine components
comprising: flowing a hot gas across a first bucket and second
bucket, wherein the first and second buckets are adjacent; flowing
a cooling air flow through a radially inner portion of the first
and second buckets; and positioning a pin between the first and
second buckets, wherein a magnetic property urges the pin toward a
first slashface of the first bucket, wherein the pin reduces fluid
flow between the first and second buckets.
11. The method of claim 10, wherein positioning the pin comprises
positioning the pin in a recess formed in a second slashface.
12. The method of claim 10, wherein the magnetic property is caused
by a magnetic layer on the pin.
13. The method of claim 12, wherein the magnetic layer is applied
by a spray.
14. The method of claim 9, wherein positioning the pin comprises
having a magnetic property of the first slashface urge the pin
toward the first slashface.
15. A turbine assembly comprising: a first component with a first
surface, a second component with a second surface configured to be
adjacent to the first surface when the first and second components
are adjacent; and a member configured to be placed between the
first and second components, wherein the member is magnetically
urged toward the first surface to reduce fluid flow between the
first and second components.
16. The turbine assembly of claim 15, comprising a recess formed in
the second surface to receive the member.
17. The turbine assembly of claim 15, wherein the member is
magnetically urged by a magnetic layer on the member.
18. The turbine assembly of claim 17, wherein the magnetic layer is
applied to the member by a spray.
19. The turbine assembly of claim 15, wherein first surface has a
magnetic property to urge the member toward the first surface.
20. The turbine assembly of claim 19, wherein the magnetic property
of the first surface is caused by a magnetic layer on the first
surface.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to gas turbines.
More particularly, the subject matter relates to reducing fluid
flow between components or regions of gas turbines.
[0002] In a gas turbine, a combustor converts chemical energy of a
fuel or an air-fuel mixture into thermal energy. The thermal energy
is conveyed by a fluid, often compressed hot air from a compressor,
to a turbine where the thermal energy is converted to mechanical
energy. In some turbine embodiments, leakage of fluid between
components into the compressed hot air causes a reduced power
output and lower efficiency for the turbine. Further, leakage of
compressed hot air into regions that are typically cooled by
cooling fluid can cause component wear, which can lead to downtime
for component repair or replacement. Leaks of fluid may be caused
by thermal expansion of certain components and relative movement
between components during operation of the gas turbine.
Accordingly, reducing fluid leaks between components can improve
efficiency and durability of the gas turbine.
BRIEF DESCRIPTION OF THE INVENTION
[0003] According to one aspect of the invention, a turbine assembly
includes a first bucket with a first slashface and a second bucket
including a recess formed in a second slashface of the second
bucket, wherein the second slashface is adjacent to the first
slashface when the first bucket is positioned adjacent to the
second bucket. The turbine assembly also includes a pin configured
to be placed in the recess, wherein the pin is magnetically urged
toward the first slashface to reduce fluid flow between the first
and second buckets.
[0004] According to another aspect of the invention, a method for
reducing fluid flow between turbine components includes flowing a
hot gas across a first bucket and second bucket, wherein the first
and second buckets are adjacent. The method also includes flowing a
cooling air flow through a radially inner portion of the first and
second buckets and positioning a pin between the first and second
buckets, wherein a magnetic property urges the pin toward a first
slashface of the first bucket, wherein the pin reduces fluid flow
between the first and second buckets.
[0005] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0006] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0007] FIG. 1 is a schematic drawing of an embodiment of a gas
turbine engine, including a combustor, fuel nozzle, compressor and
turbine;
[0008] FIGS. 2A and 2B are front and rear views, respectively, of a
portion of an exemplary turbine assembly; and
[0009] FIG. 3 is detailed end side view of an exemplary turbine
assembly.
[0010] The detailed description explains embodiments of the
invention, together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0011] FIG. 1 is a schematic diagram of an embodiment of a gas
turbine system 100. The system 100 includes a compressor 102, a
combustor 104, a turbine 106, a shaft 108 and a fuel nozzle 110. In
an embodiment, the system 100 may include a plurality of
compressors 102, combustors 104, turbines 106, shafts 108 and fuel
nozzles 110. The compressor 102 and turbine 106 are coupled by the
shaft 108. The shaft 108 may be a single shaft or a plurality of
shaft segments coupled together to form shaft 108.
[0012] In an aspect, the combustor 104 uses liquid and/or gas fuel,
such as natural gas or a hydrogen rich synthetic gas, to run the
engine. For example, fuel nozzles 110 are in fluid communication
with an air supply and a fuel supply 112. The fuel nozzles 110
create an air-fuel mixture, and discharge the air-fuel mixture into
the combustor 104, thereby causing a combustion that heats a
pressurized gas. The combustor 104 directs the hot pressurized
exhaust gas through a transition piece into a turbine nozzle (or
"stage one nozzle") and then a turbine bucket, causing turbine 106
rotation. The rotation of turbine 106 causes the shaft 108 to
rotate, thereby compressing the air as it flows into the compressor
102. The turbine components or parts are configured to be assembled
with tolerances or gaps to allow for thermal expansion and relative
movement of the parts while hot gas flows through the turbine 106.
By reducing flow of a fluid that is cooler than the hot gas into
the hot gas path, turbine efficiency is improved. Specifically,
reducing leakage of fluid into the hot gas path or compressed gas
flow increases the volume of hot gas flow along the desired path,
enabling more work to be extracted from the hot gas. Further,
restricting or reducing flow of hot gas into cooling air enables a
pressure difference between the fluids to be maintained and allows
the cooling air to be directed to various parts of the turbine for
cooling. Methods, systems and arrangements to reduce fluid leakage
between turbine parts, such as stators and rotors, are discussed in
detail below with reference to FIGS. 2A, 2B and 3. The depicted
arrangements provide improved sealing or restriction of fluid flow
between turbine components.
[0013] As used herein, "downstream" and "upstream" are terms that
indicate a direction relative to the flow of working fluid through
the turbine. As such, the term "downstream" refers to a direction
that generally corresponds to the direction of the flow of working
fluid, and the term "upstream" generally refers to the direction
that is opposite of the direction of flow of working fluid. The
term "radial" refers to movement or position perpendicular to an
axis or center line. It may be useful to describe parts that are at
differing radial positions with regard to an axis. In this case, if
a first component resides closer to the axis than a second
component, it may be stated herein that the first component is
"radially inward" of the second component. If, on the other hand,
the first component resides further from the axis than the second
component, it may be stated herein that the first component is
"radially outward" or "outboard" of the second component. The term
"axial" refers to movement or position parallel to an axis.
Finally, the term "circumferential" refers to movement or position
around an axis. Although the following discussion primarily focuses
on gas turbines, the concepts discussed are not limited to gas
turbines.
[0014] A portion of an exemplary turbine assembly is shown in FIGS.
2A and 2B. FIG. 2A is a front view of a first bucket 202 while FIG.
2B is a rear view of a second bucket 204 and members, such as pins
206, to be placed between the first bucket 202 and second bucket
204. The first bucket 202 includes a shank 208, a platform 210 and
an airfoil 212 or blade. A slashface 214 of the first bucket 202 is
configured to be adjacent to a slashface 216 of the second bucket
204 when the buckets are installed on a wheel or disk with the
slashface surfaces facing each other. The second bucket 204
includes a shank 218, a platform 220 and an airfoil 222 or blade.
Recesses 224 and 226 (also referred to as "pockets" or "seal
slots") are located in the slashface 216 to receive pins 206,
wherein the pins 206 reduce or restrict fluid flow between the
first and second buckets 202, 204 when adjoining each other in the
turbine. For example, the pins 206 are placed in the recesses 224,
226 to reduce flow of a hot gas 228 radially inward into a cooling
air 230 and reduce flow of the cooling air 230 radially outward
into the hot gas 228. Further, the pins 206 reduce axial flow 232
(i.e. along a turbine axis 250) of fluid between the adjacent
buckets 202, 204. Reducing fluid flow across the shanks 208 and 218
can help maintain a pressure (referred to as "positive pressure" or
"pressure difference") in the cooling air 230 relative to the hot
gas 228, thereby enabling distribution of the cooling air 230
throughout the turbine to reduce thermal fatigue and wear.
Moreover, preventing cooling fluid 230 from entering the hot gas
228 flow enables more work to be extracted from the hot gas 228 to
improve turbine efficiency.
[0015] In an embodiment, the pins 206 have a magnetic property,
such as a magnetic layer 234, that urges the pins toward the
slashfaces 214 to improve the seal or flow restriction. In
embodiments, the slashface 214 has a magnetic property, such as a
magnetic layer 236, that urges the pins toward the slashface 214 to
improve the seal or flow restriction. A magnetic property in the
slashface 216, such as magnetic layer 238, may also urge the pins
206 toward slashface 214. In an example, the magnetic property in
slashface 216 and recesses 224, 226 repel the pins from the
slashface surface. The magnetic properties and corresponding layers
may be on a portion or substantially the entire surface of the pins
206, slashface 214 and slashface 216. The pins 206 are urged toward
the slashface 214 via at least one of the magnetic properties of
the pins 206, slashface 214 and slashface 216.
[0016] In an embodiment, the slashfaces 214 and 216, pins 206
and/or their magnetic layers include magnetic material that
provides the desired magnetic properties, including, but not
limited to, Alnico and Samarium Cobalt (SmCo.sub.5). For example,
Alnico or Samarium Cobalt may be applied as a layer or added to the
part materials as powders, wherein the powders are capable of
retaining magnetic properties at about 1000 degrees Fahrenheit. In
another embodiment, the magnetic properties of the buckets 202, 204
and/or pins 206 are retained at about 1200 degrees Fahrenheit. In
an example, the magnetic field strength of the magnetized Alnico
buckets 202, 204 and/or pins 206 is a BHmax (the magnetic field
strength at the point of maximum energy product of a magnetic
material) of about 5 Mega Gauss Oersteds (MGOe). In another
example, the magnetic field strength of the magnetized SmCo.sub.5
buckets 202, 204 and/or pins 206 has a BHmax of about 32 MGOe.
[0017] The magnetic properties of the buckets 202, 204 and/or pins
206 may be provided by any suitable method. In one embodiment, the
magnetic property is a characteristic of the material used to form
the buckets or pins. In another embodiment, the magnetic property
is applied to the member as a layer (e.g., layers 234, 236, 238) or
coating, wherein the layer is applied to at least part of the
surface of the member. In embodiments, the magnetic layer may be an
alloy (e.g., Alnico) powder, applied by sintering, cladding,
adhesives and/or a spray, such as a cold spray. In an example where
the magnetic layer is a strip applied to the at least a part of the
surface of the slashface and/or pin, the alloy powder is blended
with a wax lubricant before the blend or mixture is compacted to
the desired shape of the strip. One or more strips are compacted to
a thickness of 30 mils and sintered at a protective hydrogen
atmosphere. In addition, the sintered strips may be tested to
ensure the desired magnetic properties are provided. The strip may
also be treated to achieve the desired strength properties.
Further, the strips may be machined down to achieve a desired
thickness to account for part expansion during heat treatment. In
another embodiment, the magnetic layer is clad to the bucket shank
or pin using a laser.
[0018] In another example, a spray technique, such as cold
spraying, may be used to apply the layer or coating of magnetic
alloy powder to the slashface and/or pins. In an embodiment, Alnico
and/or SmCo.sub.5 powders are sprayed directly on to the shank of
the buckets or pins and are then heat treated. The application
process may use a High Velocity Oxygen Fuel (HVOF) spray or cold
spray depending on the application. After application of the
magnetic layer to the selected part or parts, the magnetic
properties may be tested and/or enhanced by other suitable
techniques.
[0019] FIG. 3 is a detailed side section view of an embodiment of a
turbine assembly 300. The turbine assembly 300 includes a first
bucket 302 and second bucket 304. A member, such as a pin 310, is
positioned in a recess 312 of the first bucket to reduce fluid flow
between the buckets. As depicted, the assembled parts include the
first bucket 302 with a slashface 306 adjacent to a slashface 308
of the second bucket 304. The slashfaces 306 and 308 may be
oriented at a variety of angles with respect to a radius 314 of the
turbine and, therefore, the pin 310 may be subjected to a variety
of forces that may affect the pin's sealing properties. In an
embodiment, a force, such as a normal force, occurs at a contact
point 322, wherein the force acts to move the pin 310 away from the
slashface 308, thereby leading to an increased fluid flow between
the buckets. Further, a centrifugal force caused by rotation of the
buckets 302, 304 may also urge the pin 310 away from the slashface
308. Accordingly, in an embodiment, the slashface 308 has a
magnetic property such as a magnetic layer 318 that urges the pin
310 in a tangential direction 316 toward the slashface 308. When
the pin 310 is urged toward slashface 308, the contact between the
pin and slashface provides a seal or fluid restriction to prevent
flow of fluid between the first and second buckets 302 and 304. In
an embodiment, the recess 312 has a magnetic property, such as a
magnetic layer 320 to repel or urge the pin 310 toward the
slashface 308. Further, the pin 310 may also have a magnetic
property, such as magnetic layer 324, which urges the pin 310 in
the direction 316 toward the slashface 308. In embodiments,
magnetic properties of the recess 312 (in slashface 306), slashface
308, pin 310 or any combination thereof provide urging of the pin
310 toward slashface 308. The magnetic properties may include any
suitable material or treatment of material, including layers and/or
strips, applied by any suitable method to one or more parts of the
turbine bucket assembly.
[0020] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *