U.S. patent application number 12/208369 was filed with the patent office on 2010-03-11 for airfoil and methods of laser shock peening of airfoil.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to John McConnell Delvaux, Swami Ganesh.
Application Number | 20100061863 12/208369 |
Document ID | / |
Family ID | 41347747 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100061863 |
Kind Code |
A1 |
Delvaux; John McConnell ; et
al. |
March 11, 2010 |
AIRFOIL AND METHODS OF LASER SHOCK PEENING OF AIRFOIL
Abstract
A blade for rotating equipment. The blade includes a root and an
airfoil with a leading edge attached to the root. The blade may
include a laser shot peened root patch extending along the leading
edge and the root.
Inventors: |
Delvaux; John McConnell;
(Greer, SC) ; Ganesh; Swami; (Clifton Park,
NY) |
Correspondence
Address: |
SUTHERLAND ASBILL & BRENNAN LLP
999 PEACHTREE STREET, N.E.
ATLANTA
GA
30309
US
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
41347747 |
Appl. No.: |
12/208369 |
Filed: |
September 11, 2008 |
Current U.S.
Class: |
416/241R ;
148/525; 219/121.68 |
Current CPC
Class: |
B23K 2103/14 20180801;
B23K 2103/08 20180801; B23K 26/0006 20130101; F01D 5/286 20130101;
B23K 26/356 20151001; B23K 2103/26 20180801; C21D 10/005 20130101;
B23K 2103/02 20180801 |
Class at
Publication: |
416/241.R ;
148/525; 219/121.68 |
International
Class: |
F01D 5/28 20060101
F01D005/28; C21D 10/00 20060101 C21D010/00; F01D 5/14 20060101
F01D005/14 |
Claims
1. A blade for rotating equipment, comprising: a root; an airfoil
attached to the root; the airfoil comprising a leading edge; and a
laser shot peened root patch extending along the leading edge and
the root.
2. The blade of claim 1, wherein the laser shot peened root patch
further comprises a shot peened root patch.
3. The blade of claim 1, wherein the leading edge comprises a
leading edge treated area.
4. The blade of claim 3, wherein the leading edge treated area
extends from the laser shot peened root patch.
5. The blade of claim 3, wherein the leading edge treated area is
separated from the laser shot peened root patch.
6. The blade of claim 1, wherein the airfoil comprises a trailing
edge and wherein the trailing edge comprises a trailing edge
treated area.
7. The blade of claim 1, wherein the airfoil comprises a tip and
wherein the tip comprises a tip treated area.
8. A method of laser shock peening a blade for a turbine,
comprising: applying laser shock peening to a leading edge of the
blade about a root thereof, and applying laser shock peening to the
root of the blade about the leading edge thereof.
9. The method of clam 8, further comprising applying laser shock
peening to another portion of the leading edge of the blade.
10. The method of clam 9, wherein the other portion of the leading
edge of the blade comprises the entire leading edge.
11. The method of clam 8, further comprising applying laser shock
peening to a trailing edge of the blade.
12. The method of clam 8, further comprising applying laser shock
peening to a tip of the blade.
13. The method of claim 8, further comprising applying shot peening
to the blade.
14. The method of claim 8, wherein the step of applying laser shock
peening to a leading edge of the blade about a root thereof
comprises applying laser shock peening to a new blade.
15. The method of claim 8, wherein the step of applying laser shock
peening to a leading edge of the blade about a root thereof
comprises applying laser shock peening to a used blade.
16. A blade for rotating equipment, comprising: a root; an airfoil
attached to the root; the airfoil comprising a leading edge; a
laser shock peened root patch extending along the leading edge and
the root; and a leading edge laser shock peened area extending
along the leading edge.
17. The blade of claim 16, wherein the leading edge laser shock
peened extends from the laser shock peened root patch.
18. The blade of claim 16, wherein the leading edge laser shock
peened is separated from the laser shock peened root patch.
19. The blade of claim 16, wherein the airfoil comprises a trailing
edge and wherein the trailing edge comprises a trailing edge
treated area.
20. The blade of claim 16, wherein the airfoil comprises a tip and
wherein the tip comprises a tip treated area.
Description
TECHNICAL FIELD
[0001] The present application relates generally to gas turbine
engines and more particularly relates to a turbine airfoil and a
method of laser shock peening about the root of an airfoil.
BACKGROUND OF THE INVENTION
[0002] Damage to the surface of a gas turbine airfoil may come from
many sources. These sources may include, but are not limited to,
damage caused by tip rubs, water wash erosion, crevice corrosion,
pitting, foreign object damage, dovetail wear, etc. These damage
mechanisms may significantly reduce the vibratory strength of an
airfoil as they may produce stress risers at the damage site.
Vibratory response is a common phenomenon from the interaction of
unsteady air pressure loads and the airfoil mode shape. The airfoil
designs therefore should be able to withstand these vibratory
stresses for exceedingly long periods of time before necessitating
routine inspection and maintenance.
[0003] Current compressor airfoil designs may accomplish these
durability goals by optimizing the distribution of airfoil
thickness and chord. These current designs also may employ the use
of generous fillets in high stress transition regions such as at
the airfoil root and attachment.
[0004] One method of further enhancing airfoil durability is
through the use of laser shock peening techniques. As is known,
laser shock peening is a process for producing a region of deep
compressive residual stresses on the surface of a metal article.
Specifically, laser shock peening typically uses one or more
radiation pulses from high and low power pulsed lasers to produce
an intense shockwave at the surface of an article. The pulsed laser
beam produces a strong localized compressive force on a portion of
the surface. These deep and compressive stresses in the article
generated by laser shock peening thus may result in improved
fatigue strength. As such, treating an airfoil may provide improved
immunity within the treated area against the damaging effects of
erosion, corrosion, and foreign/domestic object damage and other
types of surface damage.
[0005] Laser shock peening, however, has not been used about the
leading edge of an airfoil root on the belief that the tensile
residual stresses may combine with the typical high mean stresses
in the airfoil. Such stress combinations may promote damage or even
failure of the airfoil as opposed to improving fatigue strength. As
such, airfoil root stresses and damage generally remain a concern
and hence the subject of routine inspection.
[0006] These stress and damage concerns are particularly at issue
about an RO compressor blade. The RO blade is the front or the
first stage compressor blade. The RO blade thus may face more
potential damage than the other blade stages given this
positioning.
[0007] Thus, there is a desire for an improved airfoil and an
improved method of laser shock peening an airfoil, including the
root portion, so as to provide improved durability. This improved
durability should improve overall system reliability and
efficiency.
SUMMARY OF THE INVENTION
[0008] The present application thus provides a blade for rotating
equipment. The blade includes a root and an airfoil with a leading
edge attached to the root. The blade may include a laser shot
peened root patch extending along the leading edge and the
root.
[0009] The present application further provides a method of laser
shock peening a blade for a turbine. The method includes the steps
of applying laser shock peening to a leading edge of the blade
about a root thereof and applying laser shock peening to the root
of the blade about the leading edge thereof.
[0010] The present application further provides a blade for
rotating equipment. The blade may include a root and an airfoil
with a leading edge attached to the root. A laser shock peened root
patch extends along the leading edge and the root and a leading
edge laser shock peened area extends along the leading edge.
[0011] These and other features of the present application will
become apparent to one of ordinary skill in the art upon review of
the following detailed description when taken in conjunction with
the drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a known airfoil.
[0013] FIG. 2 is a perspective view of an airfoil with several
areas treated by laser shock peening.
[0014] FIG. 3 is a perspective view of the root portion of the
airfoil of FIG. 2 as treated by laser shock peening as is described
herein.
DETAILED DESCRIPTION
[0015] Referring now to the drawings, in which like numerals refer
to like elements throughout the several views, FIG. 1 shows a blade
100 as may be described herein. In this example, the blade 100 may
be an RO compressor blade 110. Other blades 100 also may be used
herein. As described above, an RO compressor blade refers to the
first stage compressor blade in, for example, an F Class turbine
sold by the General Electric Company of Schenectady, N.Y. The blade
100, however, may be used with any type of rotating equipment in
any location. The blade 100 may be made out of an alloy based on
titanium, iron, nickel, or combinations thereof. The blade 100 may
be made out of other types of materials.
[0016] The blade 110 may include an airfoil 120, a platform 130,
and a shank 140. The shank 140 may include a dovetail 150 for
positioning the blade 110 within a slot of a rotating disk (not
shown). The airfoil 120 may have a leading edge 160, a trailing
edge 170, a tip 180, and a root 190. The airfoil 120 also includes
a suction side 200 and an opposing pressure side 210. Other designs
and configurations may be used herein.
[0017] As is shown in FIG. 2, known laser shock peening techniques
have been applied to the leading edge 160 of the blade 100 to form
a leading edge treated area 220, to the trailing edge 170 to create
a trailing edge treated area 230, and to the tip 180 to create a
tip treated area 240. As is shown in FIG. 3, the blade 110
described herein also may include a root treated area or patch 250.
The root patch 250 includes treatment of the root portion 190 of
the leading edge 160. Specifically, the root patch 250 extends
around the surface of the leading edge 160 onto the root 190 about
the platform 130. The metal thicknesses about the intersection of
the root 190 and the platform 130 should be sufficient so as to
support the laser shock peening tensile load. As such, the blade
100 as a whole should not suffer significant loss in structural
integrity from the tensile stresses produced by the laser shock
peening techniques.
[0018] Specifically, the root patch 250 may extend on to the root
190, both sides of the leading edge 160 about the root 190, and
then up the leading edge 160 in whole or in part. In this example,
the root patch 250 may extend about 0.1 to about 0.2 inches (about
0.25 to about 0.5 centimeters) into the root 190, about 0.35 to
about 0.45 inches (about 0.89 to about 1.14 centimeters) on both
sides of the leading edge 160, and about two inches (about 5.1
centimeters) or more up the leading edge 160. Other dimensions and
configurations may be used herein.
[0019] As described above, the laser creates pressure pulses of
about one million pounds per square inch (about 70,300 kilograms
per square centimeter) on the metal surface. These pressure pulses
send shockwaves through the patch 250. Multiple firings in a
predefined surface pattern may impart a layer of residual
compressive stress on the surface that is substantially deeper (as
much as twenty times or more) than may be attainable from
conventional peening techniques. Deeper levels of compressive
stress may provide greater resistance to fatigue and corrosion
failure. Laser shock peening thus provides a deep compressive layer
with minimal cold working that increases resistance to failure
mechanisms such a fatigue, fretting fatigue, stress corrosion, and
the like. A secondary benefit may be that thermal relaxation of the
residual stresses of a laser peening surface is less than a shock
peening surface due to the reduced cold work that is generally
involved.
[0020] Laser shock peening thus may provide a significant
improvement in fatigue resistance as well as tolerance to
significant damage depth well in excess of about 0.030 inches
(about 0.762 millimeters) without any loss of fatigue capability as
compared to conventional shot peening that would suffer significant
loss in fatigue resistance even with damage as shallow as about
0.005 inches (about 0.127 millimeters). The damage referred to here
may stem from manufacturing, assembly, handling or turbine
operation from causes such as foreign object damage; domestic
object damage; water droplet erosion; solid particle erosion;
corrosion pitting; stress corrosion cracking; fretting wear;
sliding wear; tip rub wear; manufacturing defects associated with
the melting, forging, heat treatment and machining of the turbine
components; and handling or machining damage such as gouges and
notches.
[0021] The techniques described herein may be used with a new, a
used, or even a somewhat damaged blade 110. Specifically, the laser
shock peening techniques as described herein may increase the
amount of vibratory stress needed to fail a blade 110 with nicks,
dings, or erosion to a level greater than that of even a new blade
110 without laser shock peening.
[0022] The combination of conventional shot peening with laser
shock peening also may provide additional benefits. For example,
the entire airfoil 120 may be subject to traditional shot peening
while only some areas, such as the areas 220-250, also may be laser
shock peened. Other configurations may be used herein.
[0023] It should be apparent that the foregoing relates only to
certain embodiments of the present application and that numerous
changes and modifications may be made herein by one of ordinary
skill in the art without departing from the general spirit and
scope of the invention as defined by the following claims and the
equivalents thereof.
* * * * *