U.S. patent application number 12/155728 was filed with the patent office on 2009-12-10 for axially oriented shingle face seal for turbine rotor and related method.
This patent application is currently assigned to General Electric Company. Invention is credited to Shorya Awtar.
Application Number | 20090304493 12/155728 |
Document ID | / |
Family ID | 41400476 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090304493 |
Kind Code |
A1 |
Awtar; Shorya |
December 10, 2009 |
Axially oriented shingle face seal for turbine rotor and related
method
Abstract
An axial seal arrangement is provided between a rotor and a
stator. The rotor is provided with a first disk having a
substantially flat sealing face surface. The stator is provided
with a second annular disk surrounding the rotor, supporting
proximate ends of a plurality of axially extending, flexible,
compliant seal elements arranged in an annular array of plural,
circumferentially-overlapping radial layers to thereby provide a
tortuous path for radially outward leakage flow.
Inventors: |
Awtar; Shorya; (Ann Arbor,
MI) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
41400476 |
Appl. No.: |
12/155728 |
Filed: |
June 9, 2008 |
Current U.S.
Class: |
415/1 ;
415/174.3 |
Current CPC
Class: |
F01D 11/02 20130101;
F16J 15/44 20130101; F16J 15/3288 20130101; F16J 15/3292 20130101;
F16J 15/3456 20130101 |
Class at
Publication: |
415/1 ;
415/174.3 |
International
Class: |
F01D 11/12 20060101
F01D011/12 |
Claims
1. An axial seal arrangement between a rotor and a stator
comprising: a rotor provided with a first annular disk having a
substantially flat annular sealing surface; a stator provided with
a second annular disk surrounding the rotor, said second annular
disk supporting proximate ends of a plurality of flexible,
compliant seal elements arranged in an annular array about the
rotor and extending axially towards said annular sealing
surface.
2. The axial seal arrangement of claim 1 wherein said stator is
provided with axially extending inner and outer rings secured to
said second annular disk, said compliant seal elements located
radially between said inner and outer rings.
3. The axial seal arrangement of claim 1 wherein said compliant
seal elements comprise bristles having round cross-sectional
shapes.
4. The axial seal arrangement of claim 1 wherein said compliant
seal elements comprise plural leaf seal elements.
5. The axial seal arrangement of claim 1 wherein said compliant
seal elements comprise plural annular rows of seal elements, said
plural annular rows offset in a circumferential direction.
6. An axial seal arrangement between a rotor and a stator
comprising: a rotor provided with a first disk having a
substantially flat axial sealing surface; a stator provided with a
second disk surrounding the rotor, said second disk supporting
proximate ends of a plurality of flexible compliant seal elements
extending axially towards said axial sealing surface, said seal
elements arranged in a plurality of radially spaced, annular and
circumferentially overlapping rows to thereby provide a tortuous
path for radially outward leakage flow; wherein said stator is
provided with axially extending inner and outer rings secured to
said second disk, said compliant seal elements located radially
between said inner and outer rings.
7. The axial seal arrangement of claim 6 wherein each of said
flexible, compliant seal elements has a rectangular cross-sectional
shape.
8. A method of reducing leakage flow between a rotor and a stator
comprising: (a) establishing a first radially extending surface on
the rotor; (b) establishing a second radially extending surface on
the stator; and (c) locating a plurality of axially extending,
flexible, compliant seal elements between said first and said
second surfaces.
9. The method of claim 8 wherein step (c) is carried out by
arranging said compliant seal elements in plural radial layers that
are staggered in a circumferential direction.
10. The method of claim 9 wherein said flexible, compliant seal
elements are composed of shingles, each having a rectilinear
cross-sectional shape.
11. The method of claim 9 wherein said flexible compliant seal
elements are composed of bristles, each having a round
cross-sectional shape.
12. The method of claim 8 wherein said compliant seal elements are
attached to said second surface.
13. The method of claim 8 wherein said compliant seal elements are
attached to said first surface.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to sealing structures between a
rotating component and a static component typically found in turbo
machinery and, more particularly, to an axially-oriented compliant
plate seal arrangement including staggered "shingles" that are
effective in reducing leakage in a radial direction.
[0002] Dynamic sealing between a rotating shaft, e.g., a turbine
rotor, and a casing or housing, e.g., a turbine stator, is an
important concern in turbomachinery. Several methods of sealing
have been proposed in the past. In particular, sealing based on
radially-oriented flexible members has been utilized including
seals described as leaf seals, brush seals, finger seals, shim
seals, etc.
[0003] A copending, commonly owned application Ser. No. 11/519,044
entitled, "Shaft Seal Using Shingle Members" discloses a sealing
configuration where generally radially-oriented compliant plates
(referred to as shingles) slide against a smooth, rotating
cylindrical surface, i.e., the surface of the rotor.
[0004] There remains a need, however, for a flexible seal between a
nonrotating and rotating machine components that provide good high
pressure capability as well as good leakage performance.
BRIEF DESCRIPTION OF THE INVENTION
[0005] The present invention provides an axial sealing
configuration between the machine rotating component and
surrounding machine nonrotating component.
[0006] In one aspect, the present invention relates to an axial
seal arrangement between a rotor and a stator comprising: a rotor
provided with a first annular disk having a substantially flat
annular sealing surface; a stator provided with a second annular
disk surrounding the rotor, the disk supporting proximate ends of a
plurality of axially extending, flexible, compliant seal elements
arranged in an annular array about the rotor and extending axially
towards said annular sealing surface.
[0007] In another aspect, the invention relates to an axial seal
arrangement between a rotor and a stator comprising: a rotor
provided with a first disk having a substantially flat axial
sealing surface; a stator provided with a second disk surrounding
the rotor, the second disk supporting proximate ends of a plurality
of flexible compliant seal elements extending axially towards said
axial sealing surface, said seal elements arranged in a plurality
of radially spaced, annular and circumferentially overlapping rows
to thereby provide a tortuous path for radially outward leakage
flow; wherein the stator is provided with axially extending inner
and outer rings secured to the second disk, the compliant seal
elements located radially between the inner and outer rings.
[0008] In still another aspect, the invention relates to a method
of reducing leakage flow between a rotor and a stator comprising:
(a) establishing a first radially extending surface on the rotor;
(b) establishing a second radially extending surface on the stator;
and (c) locating a plurality of axially extending, flexible,
compliant seal elements between the first and said second
surfaces.
[0009] The invention will now be described in connection with the
drawings identified below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a partial side section illustrating an axial
sealing configuration in accordance with an exemplary
implementation of the invention disclosed herein; and
[0011] FIG. 2 represents a section through the seal of FIG. 1 but
illustrating various possible alternative arrays of flexible
sealing elements.
DETAILED DESCRIPTION OF THE INVENTION
[0012] In one non-limiting implementation shown in FIG. 1, a rotor
or machine shaft 10 is arranged for rotation about a machine or
rotor axis A. The rotor 10 is provided with an integral or attached
radial disk 12 that is oriented substantially perpendicular to the
shaft 10. The disk 12 is formed with a first annular sealing
surface 14 that is substantially flat, and that cooperates with
remote ends of the compliant shingles in the shingle-face seal
described below.
[0013] A stator 16 which surrounds the rotor 10, is formed with an
integral or attached annular plate or disk 18 formed with a center
opening 20 through which the rotor 10 passes. The annular disk 18
is thus substantially concentric with the rotor and substantially
parallel to the rotor disk 12. The disk 18 thus presents a second
annular surface 22 (shown to be flat but need not be) opposed to,
and axially spaced from, the first annular sealing surface 14.
Inner and outer parallel rings 24 and 26 are attached (e.g., by
welding) to the stator disk 18 and extend axially toward the disk
12. The rings 24, 26 are substantially concentric with respect to
the rotor 10. Between the rings 24 and 26, an array of compliant
plate seal elements or shingles 28 are supported from the second
annular surface 22. These compliant shingles 28 are arranged in an
array of radially-spaced annular layers or rows 30, 32, 34 and 36,
best seen in FIG. 2. The respective annular rows are
circumferentially offset thus creating the shingled effect. In an
at-rest position, the remote ends of the shingles 28 might, in some
applications, engage the surface 14 of disk 12, while in other
applications, the remote ends of the shingles may be positioned at
some nominal distance from the surface 14.
[0014] During operation of the turbo-machine, however, the seal is
designed such that, as the rotor moves relative to the stator, the
remote ends of the shingles do not engage the annular sealing
surface 14, but do come very close to that surface. This prevents
wear, heat and debris generation while providing good sealing of
the working fluid. This axially-oriented, shingled seal arrangement
will provide reduction in leakage from a high-pressure region at
the ID of the disk 12 to a low-pressure region at the OD of the
disk 12, or vice versa. In this case, the leakage flow starts at
the ID of the rotor disk 12, passes between the gap between the
inner ring 24 and sealing surface 14 but is impeded by the tortuous
path created by the circumferentially-staggered array of shingles
28. The leakage flow finally exits through the gap between the
outer ring 26 and the sealing surface 14, to the OD region of the
rotor disc/diaphragm, as best seen in FIG. 1. The shingle geometry
may be designed such that the free ends of the shingles come close
to but do not contact the annular surface 14 during turbo-machine
operation. This provides the benefits of non-contact operation such
as reduced heat generation. A variety of shingle shapes and
cross-sections may be utilized within the scope of this invention,
depending on specific applications and sealing requirements. In
addition, it will be appreciated that the seal orientation could be
reversed, with the compliant shingles 28 and rings 24, 26,
supported on the disk 12, extending axially towards the disk
18.
[0015] The key benefits of the axially-shingled design are:
[0016] 1. In comparison to a cylindrical shingle seal
configuration, if for any reason, the compliant shingles start to
contact the annular sealing surface 14, the resulting heat
generation will not be as detrimental from a rotor-dynamic
instability stand-point. The location of the heat input is further
away from the rotor center line and furthermore, the disk 12 is
better able to dissipate the heat.
[0017] 2. In comparison to a brush seal, the shingle face seal can
be designed with a large fence height (fence height is the axial
gap between the ring 24 (and/or ring 26) and the flat annular
surface 14), to accommodate large axial excursions, since the
shingles 28 do not rely on the inner and outer rings 24, 26 for
radial support. This is an improvement over brush elements that
necessitate a small fence height due to their lack of stiffness in
the leakage flow direction, which in turn limits their
effectiveness in high pressure drop applications.
[0018] FIG. 2 also shows an alternative axial sealing arrangement
where the seal elements comprise an array of axially oriented
"brush bristles" 40, also staggered in both radial and
circumferential directions. However, due to the aspect ratio of
their cross-sections, the bristles 40 are compliant not only in the
axial direction, which is desirable to handle rotor axial
excursions, but also in the radial direction, which might be
undesirable since this limits the pressure capability of the
seal.
[0019] In still another arrangement, also shown in FIG. 2, an axial
leaf seal 42 is composed of a plurality of axially extending leaf
seal elements 44. Because of the leaf element geometry, these are
better suited to handle larger pressure drops, but present larger
gaps between adjacent leaves at the seal OD as compared to the seal
ID. Furthermore, the leaf seal elements may not be stacked with
zero gaps even at the ID as this might result in a high stiffness
in the axial direction, which is undesirable.
[0020] Accordingly, the shingled-seal arrangement is presently
preferred insofar as it provides not only the necessary radial
stiffness to allow high pressure capability, but also the staggered
or shingled arrangement of the compliant seal elements 28 pose a
significantly greater obstacle to radial leakage flow by reason of
the tortuous path created by the shingled arrangement. Furthermore,
the seal may be designed for non-contact operation which greatly
enhances the seal durability while avoiding heat-related
problems.
[0021] It will be understood that in each case, the seal elements
28, 40 and 44 extend substantially axially between the disks 18 and
12, and extend circumferentially 360.degree. about the rotor, and
that FIG. 2 is merely intended to illustrate alternative compliant
sealing elements.
[0022] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *