U.S. patent number RE39,630 [Application Number 10/937,867] was granted by the patent office on 2007-05-15 for turbine blisk rim friction finger damper.
This patent grant is currently assigned to United Technologies Corporation. Invention is credited to Roger Eric Berenson, Gary Alan Davis, Eric J. Krieg, Maynard L. Stangeland.
United States Patent |
RE39,630 |
Stangeland , et al. |
May 15, 2007 |
Turbine blisk rim friction finger damper
Abstract
A damper for reducing vibrations in an integrally bladed turbine
disk is provided. The damper includes an annular member and a
plurality of fingers. The annular member is configured so that it
is coupled to a face of the integrally bladed turbine disk. The
plurality of fingers are circumferentially spaced around the
annular member. Each of the fingers includes a base portion which
is coupled to the annular member and extends radially therefrom.
Each of the fingers is tangentially movable relative to the annular
member when the turbine disk vibrates in a diametral mode shape
such that the plurality of fingers contacts a surface of the
turbine disk to absorb vibrations.
Inventors: |
Stangeland; Maynard L.
(Thousand Oaks, CA), Berenson; Roger Eric (Moorpark, CA),
Davis; Gary Alan (Camarillo, CA), Krieg; Eric J. (Simi
Valley, CA) |
Assignee: |
United Technologies Corporation
(Hartford, CT)
|
Family
ID: |
24552330 |
Appl.
No.: |
10/937,867 |
Filed: |
September 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09636536 |
Aug 10, 2000 |
06375428 |
Apr 23, 2002 |
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Current U.S.
Class: |
416/190;
416/193A; 416/500 |
Current CPC
Class: |
F01D
5/10 (20130101); F01D 5/26 (20130101); Y10S
416/50 (20130101) |
Current International
Class: |
F01D
25/04 (20060101) |
Field of
Search: |
;415/119,190
;416/193A,234,500 ;74/574 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 186 638 |
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Jul 1986 |
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EP |
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168 997 |
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Sep 1921 |
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GB |
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2 255 138 |
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Oct 1992 |
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GB |
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Primary Examiner: Nguyen; Ninh H.
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Claims
What is claimed is:
1. A damper for damping vibration in an integrally bladed turbine
disk, the damper comprising: an annular member .Iadd.having an
axial center .Iaddend.adapted for being coupled to the integrally
bladed turbine disk; .[.and.]. a plurality of fingers spaced
circumferentially around the annular member, each of the fingers
having a base portion which is coupled to the annular member and
extending radially therefrom; wherein each of the fingers is
tangentially movable relative to the annular member when the
turbine disk vibrates in a diametral mode shape such that the
plurality of fingers contacts a surface of the turbine disk to
absorb vibrations.[...]. .Iadd.; and wherein the base portion of
each of the fingers is defined by a plurality of circumferentially
spaced, elongated slots extending orthogonal to a radial line
bisecting the axial center..Iaddend.
2. The damper of claim 1, wherein each of the plurality of fingers
includes a frictional surface adapted to contact a face of the
integrally bladed turbine disk.
3. The damper of claim 2, wherein the frictional surface of each of
the plurality of fingers is arcuate in shape.
4. The damper of claim 2, wherein the frictional surface is formed
from a material that is resistant to fretting.
5. The damper of claim 1, wherein the annular member and the
plurality of fingers are integrally formed.
.[.6. The damper of claim 5, wherein each base portion is formed by
a pair of circumferentially spaced, radially extending
slots..].
7. The damper of claim .[.6.]. .Iadd.1.Iaddend., wherein each of
the plurality of fingers is further defined by a pair of
circumferentially-spaced, radially-extending slots, each of the
circumferentially-spaced, radially .[.oriented.]. .Iadd.extending
.Iaddend.slots intersecting one of the circumferentially-spaced,
.[.radially extending.]. .Iadd.elongated .Iaddend.slots, the
circumferentially-spaced, radially .[.oriented.]. .Iadd.extending
.Iaddend.slots cooperating with the circumferentially-spaced,
.[.radially extending.]. .Iadd.elongated .Iaddend.slots to provide
the plurality of fingers with a generally T-shape.
.[.8. The damper of claim 6, wherein each of the
circumferentially-spaced, radially extending slots terminates at a
slot aperture for reducing a concentration of stress at an
intersection between the annular member and the plurality of
fingers..].
9. The damper of claim 5, wherein the annular member is a
continuous hoop.
10. An integrally bladed turbine disk assembly comprising: an
integrally bladed turbine disk; .[.and.]. a damper for damping
vibration in the integrally bladed turbine disk, the damper
including an annular member and a plurality of fingers, the annular
member coupled to an axial face of the integrally bladed turbine
disk, the plurality of fingers coupled to and circumferentially
spaced around the annular member, each of the fingers having a base
portion coupled to the annular member and extending radially
outwardly therefrom, each of the fingers including a contact
surface for contacting the axial face of the integrally bladed
turbine disk; wherein the annular member and the plurality of
fingers are integrally formed and each of the fingers is adapted to
move tangentially relative to the annular member such that contact
between the contact surface and the axial face of the integrally
bladed turbine disk reduces vibrations in the integrally bladed
turbine disk when the integrally bladed turbine disk vibrates in a
diametral mode shape.[...]. .Iadd.; and wherein the base portion of
each of the fingers is defined by a plurality of circumferentially
spaced, generally circular openings each communicating with a
radially extending slot..Iaddend.
.[.11. The integrally bladed turbine disk assembly of claim 10,
wherein each base portion is formed by a pair of circumferentially
spaced, radially extending slots..].
.[.12. The integrally bladed turbine disk assembly of claim 11,
wherein each of the plurality of fingers is further defined by a
pair of circumferentially-spaced, radially-extending slots, each of
the circumferentially-spaced, radially oriented slots intersecting
one of the circumferentially-spaced, radially extending slots, the
circumferentially-spaced, radially oriented slots cooperating with
the circumferentially-spaced, radially extending slots to provide
the plurality of fingers with a generally T-shape..].
13. The integrally bladed turbine disk assembly of claim 10,
wherein the annular member is a continuous hoop.
14. The integrally bladed turbine disk assembly of claim 10,
wherein the annular member is shrunk-fit into a cavity formed into
the axial face.
15. The integrally bladed turbine disk assembly of claim 10,
wherein a plurality of fasteners are employed to fixedly couple the
annular member to the axial face.
16. The integrally bladed turbine disk assembly of claim 15,
wherein contact between the plurality of fingers and the axial face
of the integrally bladed turbine disk generates a contact force
which is applied to the integrally bladed turbine disk in a
direction that is normal to the contact surface.
17. The integrally bladed turbine disk assembly of claim 16,
wherein the contact force is received by an arcuate pocket formed
into the axial face of the integrally bladed turbine disk.
18. The integrally bladed turbine disk assembly of claim 17,
wherein the annular member and the plurality of fingers are coated
with a material that is resistant to fretting.
19. The integrally bladed turbine disk assembly of claim 10,
wherein the contact surface is arcuately shaped.
20. The integrally bladed turbine disk assembly of claim 10,
wherein the axial face of the integrally bladed turbine disk
includes a circumferentially extending wall member having a shape
corresponding to a truncated inverse cone, the contact surface of
the plurality of fingers contacting the circumferentially extending
wall member to reduce vibrations in the integrally bladed turbine
disk when the integrally bladed turbine disk vibrates in a
diametral mode shape.
Description
TECHNICAL FIELD
The present invention relates generally to turbines and more
particularly to a damper for dampening vibration in a turbine
disk.
BACKGROUND OF THE INVENTION
Discussion
Turbine disks are commonly subject to high cycle fatigue failure
due to resonant vibration and fluid-structure instabilities. Disks
have several critical speeds wherein operation of the disk at any
one of these speeds creates an amplified traveling wave within the
disk, inducing potentially excessive dynamic stresses. At each of
these critical speeds the wave is fixed with respect to the housing
and can be excited by any asymmetries in the flow field. The
resulting resonant vibration prevents the operation of conventional
turbine disks at critical speeds. Fluid-structure instabilities
arise due to coupling between the surrounding fluid and the disk,
which can also induce excessive stresses and prevent operation at
speeds above a threshold stability boundary.
In conventional turbine disks with separate blades assembled onto a
disk, blade damping techniques are typically employed to reduce
resonant response as well as to prevent the fluid-structure
instability that results from the coupling of aerodynamic forces
and structural deflections. Accordingly, it is common practice to
control blade vibration in the gas turbine and rocket engine
industry by placing dampers between the platforms or shrouds of
individual blades attached to the disk with a dovetail or fir tree.
Such blade dampers are designed to control vibration through an
energy dissipating friction force during relative motion of
adjacent blades in tangential, axial or torsional vibration modes.
Blade dampers, in addition to the blade attachments, provide
friction dampening for both disk and blade vibration.
This damping mechanism, however, is not feasible for integrally
bladed turbine disks (blisks) unless radial slots are machined
between each blade to introduce blade shank flexibility. The added
complexity of the slots increases the rim load on the turbine disk
and defeats some of the cost, speed and weight benefits of the
blisk. Consequently, the lack of a blade attachment interface
results in a significant reduction in damping and can result in
fluid-structure instability at speeds other than the disk standing
wave critical speeds.
Rim dampers have been utilized by the gear industry to reduce
vibration in thinly webbed large diameter gears. In such
applications a split ring or series of spiral rings are preloaded
in one or more retainer grooves on the underside of the gear rim.
At relatively low rim speeds the centrifugal force on the damper
ring provides damping due to relative motion when the gear rim
experiences vibration in a diametral mode. This method of friction
damping, however, is not feasible at high rim speeds because the
centrifugal force on the damper ring is of sufficient magnitude to
cause the damper to lock-up against the rim. Lock-up occurs when
the frictional forces become large enough to restrain relative
motion at the interface, causing the damper ring to flex as an
integral part of the rim.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a damper for
an integrally bladed turbine disk which employs a plurality of
fingers to reduce the vibration of an integrally bladed turbine
disk. The damper is primarily intended to reduce vibration when the
integrally bladed turbine disk vibrates in a diametral mode shape.
However, the damper is also effective in reducing the vibration of
turbine blades mounted on the disk rim.
It is another object of the present invention to provide a damper
having a profile which applies a frictional contact force
continuously over a disk profile to direct the contact force normal
to the disk surface.
In one preferred form, the present invention provides a damper for
reducing vibrations in an integrally bladed turbine disk. The
damper includes an annular member and a plurality of fingers. The
annular member is configured so that it is retained by a radial
step on the inside face of the integrally bladed turbine disk rim.
Alternatively, conventional fasteners may be employed to couple the
annular member to the integrally bladed turbine disk rim. The
plurality of fingers are coupled to and concentrically spaced
around the annular member. Each of the fingers is adapted to
provide relative circumferential motion with respect to the inside
face of the integrally bladed turbine disk when the integrally
bladed turbine disk vibrates in a diametral mode shape. The annular
member is configured to provide structural support to the fingers
so that they apply a contact force to the integrally bladed turbine
disk that is directed normal the disk surface.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional advantages and features of the present invention will
become apparent from the subsequent description and the appended
claims, taken in conjunction with the accompanying drawings,
wherein:
FIG. 1 is a cross-sectional view of an integrally bladed turbine
disk assembly constructed in accordance with the teachings of the
present invention;
FIG. 2 is a longitudinal cross-sectional view of a portion of the
integrally bladed turbine disk assembly of FIG. 1 illustrating the
integrally bladed turbine disk;
FIG. 3 is an enlarged portion of the integrally bladed turbine disk
illustrated in FIG. 2;
FIG. 4 is a front elevational view of a portion of the integrally
bladed turbine disk assembly of FIG. 1 illustrating the damper;
FIG. 5 is an enlarged portion of the damper illustrated in FIG.
4;
FIG. 6 is a cross-sectional view of the damper taken along the line
6--6 of FIG. 4;
FIG. 7 is a cross-sectional view of the integrally bladed turbine
disk assembly of FIG. 1;
FIG. 8 is a cross-sectional view of an integrally bladed turbine
disk assembly constructed in accordance with an alternate
embodiment of the present invention;
FIG. 9 is a longitudinal cross-sectional view of the integrally
bladed turbine disk assembly of FIG. 8;
FIG. 10 is a front elevational view of a portion of the integrally
bladed turbine disk assembly of FIG. 8 illustrating the damper in
greater detail;
FIG. 11 is an enlarged view of a portion of the damper illustrated
in FIG. 10; and
FIG. 12 is a cross-sectional view of a portion of the damper taken
along the line 12--12 of FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIG. 1 of the drawings, a turbopump 10 wherein
various embodiments of the present invention may be effectively
utilized is shown in a cross-sectional view. The turbopump 10 is
shown to include an integrally bladed turbine disk assembly 12
having an integrally bladed turbine disk 14 and a damper 16.
In FIGS. 2 and 3 a portion of the integrally bladed turbine disk 14
is shown in cross-sectional view. The integrally bladed turbine
disk 14 is symmetrical about a longitudinal axis 20 and includes a
unitarily formed rotor portion 22 having a plurality of radially
extending blades 24 and an axial face 26. In the particular
embodiment illustrated, a damper cavity 28 having a first cavity
portion 30 and a second cavity portion 32 is formed into the axial
face 26. The first cavity portion 30 is formed into the axial face
26 in a direction perpendicular to the longitudinal axis 20. The
first cavity portion 30 includes an annular face 34 and a radial
lip portion 36. The second cavity portion 32 includes an arcuate
inner surface 38 which intersects the annular face 34.
The damper 16 is shown in FIGS. 4 through 6 to include an annular
member 40 and a plurality of T-shaped fingers 42 that are coupled
to and spaced circumferentially around the annular member 40. In
the particular embodiment illustrated, the annular member 40 is a
continuous hoop that is sized to engage the annular face 34 of the
first cavity portion 30. Each of the plurality of T-shaped fingers
42 includes a base portion 44 and a leg portion 46. The base
portion 44 is coupled to the annular member 40 and extends radially
inward therefrom. The leg portion 46 is coupled to a distal end of
the base portion 44 and extends tangentially therefrom. The
T-shaped fingers 42 include an arcuate outer surface 48 which is
configured to cooperate with the arcuate inner surface 38 in the
second cavity portion 32 in a manner that will be discussed in
detail below.
Preferably, the annular member 40 and the plurality of T-shaped
fingers 42 are integrally formed. Construction in this manner
permits each of the T-shaped fingers 42 to be formed by a pair of
circumferentially-spaced, tangentially-oriented slots 50 and a pair
of circumferentially-spaced, radially-extending slots 52. As shown,
each of the radially-extending slots 52 intersects one of the
tangentially-oriented slots 50.
In FIG. 7 the damper 16 is shown in operative association with the
integrally bladed turbine disk 14. The damper 16 is preferably
cooled in a liquid gas, such as liquid nitrogen, and shrunk-fit to
the damper cavity 28 during the assembly of the integrally bladed
turbine disk assembly 12. The annular member 40 provides the damper
16 with continuity to permit it to be retained in position relative
to the integrally bladed turbine disk 14. The annular member 40
also provides a mechanism for preloading the plurality of T-shaped
fingers 42 against the arcuate inner surface 38.
In operation, the radially-extending slots 52 and
tangentially-oriented slots 50 effectively decouple the tangential
motion of the annular member 40 from the T-shaped fingers 42. Due
to high centrifugal forces present in the integrally bladed turbine
disk assembly 12, the annular member 40 is forced against the
annular face 34 with sufficient force to cause lock-up. During
lock-up, relative movement between the annular member 40 and the
annular face 34 is inhibited. Due to the presence of the
radially-extending slots 52 and tangentially-oriented slots 50, the
T-shaped fingers 42 are permitted to move tangentially at the
frictional interface 54 between the integrally bladed turbine disk
14 and the damper 16 when the integrally bladed turbine disk
assembly 12 vibrates in a diametral mode shape. The friction
interface 54 includes an area where the annular member 40 and the
T-shaped fingers 42 contact the annular face 34 and the arcuate
inner surface 38, respectively. Vibration of the integrally bladed
turbine disk 14 in a diametral mode causes tangential motion
between the T-shaped fingers 42 and the arcuate inner surface 38.
The circumferential length and thickness of the radially-extending
slots 52 and tangentially-oriented slots 50 are selected to
optimize the damping, centrifugal force, and relative tangential
motion for a particular application.
Another unique feature of the damper 16 is the configuration of its
contact surface 60 (shown in FIG. 6). The contact surface 60
includes the arcuate outer surface 48 of the T-shaped fingers 42
and the annular outer surface 62 of the annular member 40. The
contact surface 60 is configured in a manner wherein the annular
member 40 provides a first contact force and the T-shaped fingers
42 provide a second contact force. The first contact force provided
by the annular member 40 is applied to the integrally bladed
turbine disk 14 in a radial direction through the annular outer
surface 62. The arcuate outer surface 48 causes the second contact
force applied by the T-shaped fingers 42 to vary constantly from a
radial direction to an axial orientation (i.e., against a radially
extending portion of the axial face 26 of the integrally bladed
turbine disk 14). Consequently, the majority of the damper
centrifugal load is transferred to the integrally bladed turbine
disk 14 through the annular member 40 while the T-shaped fingers 42
provide a much smaller contact force. Configuration in this manner
prevents lock-up between the T-shaped fingers 42 and the integrally
bladed turbine disk 14.
The frictional characteristics of the contact surface 60 may be
controlled through the finishing of contact surface 60 to a desired
surface finish or through the application of a coating, such as
silver plating or molydisulfide. Silver plating is highly desirable
as it is resistant to fretting which can result from micro-motion
between the damper 16 and the integrally bladed turbine disk
14.
While the integrally bladed turbine disk assembly 12 has been
described thus far as including a damper 16 with T-shaped fingers
42 which is shrunk-fit to a damper cavity 28 during the assembly of
the integrally bladed turbine disk assembly 12, those skilled in
the art will appreciate that the invention, in its broader aspects,
may be constructed somewhat differently. For example, the damper
16' may be coupled to a face of the integrally bladed turbine disk
14' as illustrated in FIGS. 8 and 9. In this arrangement,
integrally bladed turbine disk assembly 12' is shown to include a
pair of dampers 16' which are coupled to the integrally bladed
turbine disk 14' via a plurality of fasteners 100. Integrally
bladed turbine disk 14' is symmetrical about its longitudinal axis
20' and includes a unitarily formed rotor portion 22' having a
plurality of radially extending blades 24 and an pair of axial
faces 26'.
In the particular embodiment illustrated, a damper cavity 28'
having a first cavity portion 30' and a second cavity portion 32'
is formed into each of the axial faces 26'. The first cavity
portion 30' is formed into the axial face 26' in a direction
parallel the longitudinal axis 20'. The first cavity portion 30'
includes an plurality of fastener apertures 102. The second cavity
portion 32' is illustrated to include a circumferentially extending
wall member 104 which is skewed to the first cavity portion 30',
thereby providing the second cavity portion 32' with a shape
corresponding to a truncated inverse cone. Those skilled in the art
will understand that the shape of second cavity portion 32' may be
tailored in a desired manner to achieve specific design goals and
as such, the second cavity portion 32' may alternatively be
arcuately shaped.
In FIGS. 9 through 12, the damper 16' is shown to include an
annular member 40' and a plurality of fingers 42' that are coupled
to and spaced circumferentially around the annular member 40'. In
the particular embodiment illustrated, the annular member 40' is a
flange that abuts the first cavity portion 30'. Each of the
plurality of fingers 42' includes a base portion 44' and an end
portion 46'. The base portion 44' is coupled to the annular member
40' and extends radially inward therefrom. The end portion 46' is
coupled to a distal end of the base portion 44' and extends
therefrom to contact the second cavity portion 32'. The fingers 42'
include an outer surface 48' which is configured to cooperate with
the wall member 104 of the second cavity portion 32' in a manner
that will be discussed in detail below. Preferably, the annular
member 40' and the plurality of fingers 42' are integrally formed.
Construction in this manner permits each of the fingers 42' to be
formed by a pair of circumferentially spaced, radially extending
slots 52'. As shown, each of the radially extending slots 52'
terminates at a slot aperture 110 which is employed to reduce the
concentration of stress at the intersections between annular member
40' and each of the plurality of fingers 42' when damper 16' is in
operation.
In FIGS. 8 and 9, the plurality of fasteners 100 are illustrated to
include a plurality of externally threaded fasteners 114, a
plurality of internally threaded nuts 116 and a plurality of
dog-bone washers 118. Each of the dog-bone washers 118 is
positioned over a pair of circumferentially adjacent fastener
apertures 120 and 102 formed into the annular member 40' and the
first cavity portion 30' of the integrally bladed turbine disk 14',
respectively. Externally threaded fasteners 114 are placed through
fastener apertures 120 and 102 and internally threaded nuts 116 are
threadably engaged to the externally threaded fasteners 114 such
that a clamping force is generated by fasteners 100 to retain
annular member 40' such that annular member 40' will not rotate
about the longitudinal axis 20'.
In operation, the radially extending slots 52' effectively decouple
the tangential motion of the annular member 40' from the fingers
42'. The radially extending slots 52' permit the fingers 42' to
move tangentially at a frictional interface 54' between the
integrally bladed turbine disk 14' and the damper 16' when the
integrally bladed turbine disk assembly 12' vibrates in a diametral
mode shape. The friction interface 54' includes an area where the
fingers 42' contact the wall member 104 of the second cavity
portion 32'. Vibration of the integrally bladed turbine disk 14' in
a diametral mode is transmitted to and absorbed by damper 16'. In
this regard, the vibrations cause tangential motion in the
plurality of fingers 42' relative to wall member 104 so that the
energy of the vibrations is absorbed in the friction interface 54'
by frictional contact between the plurality of fingers 42' and the
wall member 104.
While the invention has been described in the specification and
illustrated in the drawings with reference to a preferred
embodiment, it will be understood by those skilled in the art that
various changes may be made and equivalents may be substituted for
elements thereof without departing from the scope of the invention
as defined in the claims. In addition, many modifications may be
made to adapt a particular situation or material to the teachings
of the invention without departing from the essential scope
thereof. Therefore, it is intended that the invention not be
limited to the particular embodiment illustrated by the drawings
and described in the specification as the best mode presently
contemplated for carrying out this invention, but that the
invention will include any embodiments falling within the
description of the appended claims.
* * * * *