U.S. patent application number 09/972088 was filed with the patent office on 2003-04-10 for nozzle lock for gas turbine engines.
This patent application is currently assigned to General Electric Company. Invention is credited to Enzweiler, Donald Franklin, Housley, Christopher G..
Application Number | 20030068225 09/972088 |
Document ID | / |
Family ID | 25519146 |
Filed Date | 2003-04-10 |
United States Patent
Application |
20030068225 |
Kind Code |
A1 |
Housley, Christopher G. ; et
al. |
April 10, 2003 |
NOZZLE LOCK FOR GAS TURBINE ENGINES
Abstract
A nozzle lock for circumferentially securing a nozzle segment
relative to the engine casing of a gas turbine engine. The nozzle
lock includes a thickener pad joined to an outer surface of the
engine casing and a locking member disposed in a notch located in
the outer band of the nozzle segment. A pin formed on the locking
member is press-fit into the casing and the thickener pad.
Inventors: |
Housley, Christopher G.;
(Liberty Township, OH) ; Enzweiler, Donald Franklin;
(Burlington, KY) |
Correspondence
Address: |
PIERCE ATWOOD
One Monument Square
Portland
ME
04101
US
|
Assignee: |
General Electric Company
Cincinnati
OH
|
Family ID: |
25519146 |
Appl. No.: |
09/972088 |
Filed: |
October 5, 2001 |
Current U.S.
Class: |
415/189 |
Current CPC
Class: |
F01D 9/04 20130101; F01D
25/246 20130101 |
Class at
Publication: |
415/189 |
International
Class: |
F01D 001/02 |
Claims
What is claimed is:
1. A nozzle lock for circumferentially securing a turbine nozzle
segment relative to an engine casing in a gas turbine engine, said
nozzle lock comprising: a thickener pad adapted to be joined to an
outer surface of said engine casing; a locking member adapted to be
received in a notch formed in said nozzle segment; and a pin formed
on said locking member and press-fit into said thickener pad.
2. The nozzle lock of claim 1 wherein said thickener pad has a pin
hole formed therein for receiving said pin.
3. The nozzle lock of claim 1 wherein said pin is off-centered
relative to said locking member.
4. The nozzle lock of claim 1 wherein said thickener pad has a
thickness that is approximately equal to the thickness of said
engine casing.
5. A nozzle lock for a gas turbine engine, said nozzle lock
comprising: an engine casing; at least one nozzle segment disposed
inside said engine casing, said nozzle segment including an outer
band, an inner band and at least one vane disposed between said
outer band and said inner band, said outer band having a notch
formed therein; a thickener pad joined to an outer surface of said
engine casing; a locking member disposed in said notch; and a pin
formed on said locking member and press-fit into said casing and
said thickener pad.
6. The nozzle lock of claim 5 wherein said casing and said
thickener pad each have a pin hole formed therein for receiving
said pin.
7. The nozzle lock of claim 5 wherein said pin is off-centered
relative to said locking member.
8. The nozzle lock of claim 5 wherein said locking member fits
snugly into said notch.
9. The nozzle lock of claim 5 wherein said outer band includes an
aft rail and said notch is located in said aft rail.
10. The nozzle lock of claim 5 wherein said thickener pad has a
thickness that is approximately equal to the thickness of said
engine casing.
11. The nozzle lock of claim 5 wherein said thickener pad is welded
to said engine casing.
12. The nozzle lock of claim 5 wherein said thickener pad is
integrally formed with said engine casing.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to gas turbine engines and
more particularly to nozzle locks for circumferentially securing
turbine nozzles in such engines.
[0002] A gas turbine engine includes a compressor that provides
pressurized air to a combustor wherein the air is mixed with fuel
and ignited for generating hot combustion gases. These gases flow
downstream to one or more turbines that extract energy therefrom to
power the compressor and provide useful work such as powering an
aircraft in flight. Each turbine stage commonly includes a turbine
rotor and a stationary turbine nozzle for channeling combustion
gases into the turbine rotor disposed downstream thereof. The
turbine rotor includes a plurality of circumferentially spaced
apart blades extending radially outwardly from a rotor disk that
rotates about the centerline axis of the engine. The nozzle
includes a plurality of circumferentially spaced apart vanes
radially aligned with the rotor blades. Turbine nozzles are
typically segmented around the circumference thereof with each
nozzle segment having one or more nozzle vanes disposed between
inner and outer bands that define the radial flowpath boundaries
for the hot combustion gases flowing through the nozzle.
[0003] In a typical mounting arrangement, the outer band of each
nozzle segment includes flanges or hooks for coupling the nozzle
segment to the inner surface of the engine casing. The inner bands
are ordinarily coupled to stationary support structure within the
engine. These arrangements provide radial and axial support for the
turbine nozzle. During operation, turbine nozzles also generate
substantial tangential loads because of the hot gas flow passing
therethrough. Gas turbine engines use anti-rotation devices,
referred to as nozzle locks, to circumferentially secure the
turbine nozzle relative to the engine casing and react the
tangential loads.
[0004] One known nozzle lock arrangement includes a locking member
having two lugs and an integral threaded stud. The locking member
is installed from the interior of the engine casing so that the
first lug is received in a notch formed in the outer band of one
nozzle segment and the second lug is received in a notch formed in
the outer band of an adjacent nozzle segment. The threaded stud
extends through an opening in the casing and is secured by a nut
threaded onto the stud from the exterior of the casing. This nozzle
lock arrangement causes the accumulation of nozzle load stress and
fastener pre-load stress to occur at the same location, i.e., at
the undercut fillet at the base of the threaded stud. This nozzle
lock also reacts the tangential load for two nozzle segments. As a
result, these nozzle locks can be susceptible to fatigue damage and
rupture.
[0005] Accordingly, it would be desirable to have a nozzle lock
that is less susceptible to fatigue damage and rupture.
BRIEF SUMMARY OF THE INVENTION
[0006] The above-mentioned need is met by the present invention,
which provides a nozzle lock for a gas turbine engine having an
engine casing and at least one nozzle segment disposed inside the
engine casing. The nozzle lock includes a thickener pad joined to
an outer surface of the engine casing and a locking member disposed
in a notch located in the outer band of the nozzle segment. A pin
formed on the locking member is press-fit into the casing and the
thickener pad.
[0007] The present invention and its advantages over the prior art
will become apparent upon reading the following detailed
description and the appended claims with reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The subject matter that is regarded as the invention is
particularly pointed out and distinctly claimed in the concluding
part of the specification. The invention, however, may be best
understood by reference to the following description taken in
conjunction with the accompanying drawing figures in which:
[0009] FIG. 1 is a schematic, longitudinal sectional view of an
exemplary turbofan gas turbine engine having the turbine nozzle
lock of the present invention.
[0010] FIG. 2 is a perspective view of a nozzle segment from the
gas turbine engine of FIG. 1.
[0011] FIG. 3 is a partial side view of the nozzle segment of FIG.
2.
[0012] FIG. 4 is a partial cross-sectional view of the nozzle
segment of FIG. 2.
[0013] FIG. 5 is a partial perspective view of a nozzle lock
located on an engine casing, with the nozzle segment omitted and
the casing shown in cut-away.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Referring to the drawings wherein identical reference
numerals denote the same elements throughout the various views,
FIG. 1 shows an exemplary turbofan gas turbine engine 10 including,
in serial flow communication, a fan 12, a booster or low pressure
compressor 14, a high pressure compressor 16, a combustor 18, a
high pressure turbine 20, and a low pressure turbine 22, all
disposed coaxially about a longitudinal or axial centerline axis
24. The combustor 18 includes a generally annular hollow body
defining a combustion chamber 26 therein. The booster 14 and the
high pressure compressor 16 provide compressed air that passes
primarily into the combustor 18 to support combustion and partially
around the combustor 18 where it is used to cool both the combustor
liners and turbomachinery further downstream. Fuel is introduced
into the forward end of the combustor 18 and is mixed with the air
in a conventional fashion. The resulting fuel-air mixture flows
into the combustion chamber 26 where it is ignited for generating
hot combustion gases. The hot combustion gases are discharged to
the high pressure turbine 20 located immediately downstream of the
combustor 18 where they are expanded so that energy is extracted.
The hot gases then flow to the low pressure turbine 22 where they
are expanded further. The high pressure turbine 20 drives the high
pressure compressor 14 through a high pressure shaft 28, and the
low pressure turbine 22 drives the fan 12 and the booster 14
through a low pressure shaft 30 disposed within the high pressure
shaft 28.
[0015] The high pressure turbine 20 and the low pressure turbine 22
each include a number of turbine stages disposed within an engine
casing 31. As shown in FIG. 1, the high pressure turbine 20 has two
stages and the low pressure turbine 22 has five stages, although it
should be noted that different numbers of stages are possible. Each
turbine stage includes a turbine rotor and a stationary turbine
nozzle for channeling combustion gases into the turbine rotor
disposed downstream thereof. Generally, each turbine rotor includes
a plurality of circumferentially spaced apart blades extending
radially outwardly from a rotor disk that rotates about the
centerline axis of the engine 10. The blades include airfoil
portions that extend into the gas flow. A plurality of arcuate
shrouds is arranged circumferentially in an annular array so as to
closely surround the rotor blades and thereby define the outer
radial flowpath boundary for the hot combustion gases flowing
through the turbine rotor. Each turbine nozzle generally includes a
plurality of circumferentially spaced vanes that are supported
between a number of arcuate outer bands and arcuate inner bands.
The vanes, outer bands and inner bands are arranged into a
plurality of circumferentially adjoining nozzle segments that
collectively form a complete 360.degree. assembly. The vanes have
airfoils that are configured so as to optimally direct the
combustion gases to the turbine rotor. The outer and inner bands of
each nozzle segment define the outer and inner radial boundaries,
respectively, of the gas flow through the nozzle.
[0016] FIG. 2 shows a nozzle segment 32 from one of the turbine
nozzles of the low pressure turbine 22. The nozzle segment 32 has
five vanes 34 disposed between an outer band 36 and an inner band
38. It should be noted that the present invention is not limited to
nozzle segments having five vanes, as nozzle segments having other
numbers of vanes are known. Furthermore, although the present
invention is being described herein in conjunction with a low
pressure turbine nozzle, it should be understood that the present
invention is also applicable to high pressure turbine nozzles. The
outer band 36 includes a forward rail 40 and an aft rail 42 that
are used to couple the nozzle segment 32 to the engine casing 31 in
a manner to be described below. A cutout or notch 43 is formed in
the aft rail 42, the purpose of which also will be described below.
The inner band 38 includes a plurality of flanges or rails that are
used to couple the nozzle segment 32 to stationary engine structure
in a conventional manner.
[0017] Referring now to FIGS. 3 and 4, the outer mounting
arrangement for the nozzle segment 32 is described in more detail.
Specifically, the casing 31 has a first hook 44 formed on the inner
surface thereof and a second hook 46 formed on the inner surface
thereof, aft of the first hook 44. The outer band forward rail 40
is provided with a forwardly extending flange 48 that is disposed
between the first hook 44 and the casing 31. The outer band aft
rail 42 is provided with a rearwardly extending flange 50 that is
disposed between the casing 31 and a hanger 52 supported by the
second hook 46. This arrangement provides radial and axial support
for the nozzle segment 32.
[0018] The mounting arrangement further includes a nozzle lock 54
that reacts tangential loads and prevents circumferential rotation
of the nozzle segment 32 relative to the engine casing 31.
Referring to FIG. 5 in addition to FIGS. 3 and 4, the nozzle lock
54 includes a thickener pad 56 joined to the outer surface of the
casing 31, at an axial position that is in line with the axial
location of the aft rail 42. A locking member 58 is disposed in the
notch 43 in the aft rail 42. The nozzle segment 32 is positioned
such that the notch 43, locking member 58 and thickener pad 56 are
generally all at the same circumferential position relative to the
casing 31. More particularly, the casing 31 and the thickener pad
56 are each provided with a pin hole and all of the pin holes are
aligned with one another. A press-fit pin 60 is formed on the
radially outer surface of the locking member 58. The press-fit pin
60 is inserted into the pin holes so as to secure the locking
member 58 circumferentially with respect to the casing 31. The
circumferentially fixed locking member 58 disposed in the notch 43
thus prevents circumferential rotation of the nozzle segment 32
relative to the engine casing 31.
[0019] The thickener pad 56 can be either a separate piece that is
attached to the casing 31 by any suitable means, such as a fillet
weld, or can be integrally formed with the casing 31. The use of
the thickener pad 56 thus lends itself to both field rework or
retrofits as well as new manufactures. The thickener pad 56 has
sufficient thickness so as to provide additional wheelbase for the
press-fit pin 60 to react the tangential nozzle load. In one
embodiment, the thickness of the thickener pad 56 is approximately
equal to the casing thickness. Without the thickener pad 56, the
thickness of the casing 31 alone would be insufficient to react
tangential nozzle load without distress. The pin 60 is press-fit
into the pin holes with sufficient interference to prevent the pin
60 from coming loose during engine operation. The press-fit concept
also eliminates fastener pre-load stress. Furthermore, the nozzle
lock 54 reacts the tangential load of a single nozzle segment, as
opposed to reacting the tangential load of two nozzle segments as
is the case with some prior nozzle locks.
[0020] The body of the locking member 58 is sized to fit snugly in
the notch 43 to avoid looseness and rattling. The notch 43 could be
formed in any circumferential location along the aft rail 42. The
aft rail 42 could be provided with more than one such notch for
convenience although only a single notch is sufficient. The
press-fit pin 60 is off-centered relative to the locking member 58
in the axial direction. That is, the pin 60 is closer to the aft
end of the locking member than the forward end. This means that the
locking member 58 can only be installed in the correct orientation.
The press-fit pin 60 is also provided with an increased undercut
fillet radius at the junction of the body of the locking member 58
and the pin diameter. This has a positive impact on design life
relative to current nozzle locks.
[0021] While specific embodiments of the present invention have
been described, it will be apparent to those skilled in the art
that various modifications thereto can be made without departing
from the spirit and scope of the invention as defined in the
appended claims.
* * * * *