U.S. patent application number 14/330183 was filed with the patent office on 2014-10-30 for elliptical sealing system.
The applicant listed for this patent is General Electric Company. Invention is credited to Bruce William Brisson, Farshad Ghasripoor, Roderick Mark Lusted, Franco Sarri.
Application Number | 20140321993 14/330183 |
Document ID | / |
Family ID | 51789386 |
Filed Date | 2014-10-30 |
United States Patent
Application |
20140321993 |
Kind Code |
A1 |
Lusted; Roderick Mark ; et
al. |
October 30, 2014 |
ELLIPTICAL SEALING SYSTEM
Abstract
Some embodiments of the invention are directed to an elliptical
sealing system for use with a rotor and a stator housing of a
rotary machine. The elliptical sealing system includes a plurality
of sealing segments; and an abradable coating having a uniform
thickness disposed on each of the plurality of sealing segments,
such that the plurality of sealing segments with the abradable
coating disposed thereon has a substantially elliptical shape under
all conditions when the rotor rotates and the rotor remains
stationary. A rotary machine having the elliptical sealing system
is also disclosed.
Inventors: |
Lusted; Roderick Mark;
(Niskayuna, NY) ; Brisson; Bruce William;
(Gardnerville, NV) ; Sarri; Franco; (Florence,
IT) ; Ghasripoor; Farshad; (Berkeley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
51789386 |
Appl. No.: |
14/330183 |
Filed: |
July 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12986226 |
Jan 7, 2011 |
|
|
|
14330183 |
|
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Current U.S.
Class: |
415/173.3 ;
415/173.4 |
Current CPC
Class: |
F16J 15/442 20130101;
F01D 11/003 20130101; F05D 2250/14 20130101; F01D 11/122 20130101;
F16J 15/445 20130101 |
Class at
Publication: |
415/173.3 ;
415/173.4 |
International
Class: |
F01D 11/12 20060101
F01D011/12 |
Claims
1. An elliptical sealing system for use with a rotor and a stator
housing of a rotary machine, comprising: a plurality of sealing
segments; and an abradable coating having a uniform thickness
disposed on each of the plurality of sealing segments, such that
the plurality of sealing segments with the abradable coating
disposed thereon has a substantially elliptical shape under all
conditions when the rotor rotates and the rotor remains
stationary.
2. The elliptical sealing system of claim 1, wherein the plurality
of sealing segments comprises a packing ring.
3. The elliptical sealing system of claim 1, further comprising a
plurality of biasing members mechanically coupled to the plurality
of sealing segments and the stator housing.
4. The elliptical sealing system of claim 3, wherein the plurality
of biasing members is positioned at about a 12 o'clock position and
at about a 6 o'clock position to bias the plurality of sealing
segments towards the rotor.
5. The elliptical sealing system of claim 4, wherein the plurality
of biasing members positioned at about the 6 o'clock position is
configured to effect an upward movement of an associated sealing
segment when the rotor rotates.
6. The elliptical sealing system of claim 3, wherein the plurality
of biasing members comprises a plurality of springs to bias the
plurality of sealing segments towards the rotor.
7. The elliptical sealing system of claim 1, wherein the plurality
of sealing segments comprises a first semielliptical sealing
segment and a second semielliptical sealing segment.
8. The elliptical sealing system of claim 7, wherein a first end of
the first semielliptical sealing segment is mechanically coupled to
a first end of the second semielliptical sealing segment at about a
3 o'clock position, and a second end of the first semielliptical
sealing segment is mechanically coupled to a second end of the
second semielliptical sealing segment at about a 9 o'clock
position.
9. The elliptical sealing system of claim 7, wherein coupling
joints between the first semielliptical sealing segment and the
second semielliptical sealing segment define a major axis of the
substantially elliptical shape.
10. The elliptical sealing system of claim 1, wherein the rotor
comprises a plurality of teeth mounted thereon, and wherein the
plurality of teeth engages the abradable coating.
11. The elliptical sealing system of claim 10, wherein the
plurality of teeth comprises a plurality of J-strips, and wherein
the plurality of J-strips engages at different depths in the
abradable coating along an inner circumference of the stator
housing.
12. The elliptical sealing system of claim 10, wherein the
plurality of teeth and the abradable coating are configured such
that the plurality of teeth defines an elliptical path in the
abradable coating during an initial period of rotation.
13. The elliptical sealing system of claim 10, wherein the
plurality of teeth and the abradable coating are configured such
that when the rotor rotates, an engagement of the plurality of
teeth in the abradable coating, is deeper at about a 12 o'clock
position when compared to an engagement at a 6 o'clock
position.
14. The elliptical sealing system of claim 10, wherein the
plurality of sealing segments with the abradable coating disposed
thereon has an interference engagement with the plurality of teeth
at about a 12 o'clock position and at about a 6 o'clock
position.
15. The elliptical sealing system of claim 10, wherein the
plurality of sealing segments with the abradable coating disposed
thereon has a line on line engagement with the plurality of teeth
at about a 3 o'clock position and at about a 9 o'clock
position.
16. The elliptical sealing system of claim 1, wherein the rotary
machine comprises a compressor.
17. A rotary machine, comprising: a stator housing; a rotor
comprising a plurality of teeth mounted thereon; a first
semielliptical sealing segment and a second semielliptical sealing
segment mechanically coupled to each other at about a 3 o'clock
position and about a 9 o'clock position, each of the first
semielliptical sealing segment and the second semielliptical
sealing segment comprising an abradable coating of a uniform
thickness disposed thereon, wherein the first semielliptical
sealing segment and the second semielliptical sealing segment with
the abradable coating disposed thereon have an elliptical shape
under all conditions when the rotor rotates and the rotor remains
stationary, and wherein the abradable coating has an interference
engagement with the plurality of teeth at about a 12 o'clock
position and at about a 6 o'clock position, and the abradable
coating has a line on line engagement with the plurality of teeth
at about the 3 o'clock position and at about the 9 o'clock
position.
18. The rotary machine of claim 17, further comprising a plurality
of biasing members mechanically coupled to the first semielliptical
sealing segment, the second semielliptical sealing segment, and the
stator housing, wherein the plurality of biasing members is
positioned at about the 12 o'clock position and about the 6 o'clock
position to bias the plurality of sealing segments towards the
rotor.
19. The rotary machine of claim 17, wherein the plurality of teeth
and the abradable coating are configured such that the plurality of
teeth define an elliptical path in the abradable coating when the
rotor lifts-up during an initial period of rotation.
20. The rotary machine of claim 17, wherein the plurality of teeth
and the abradable coating are configured such that when the rotor
rotates, an engagement of the plurality of teeth in the abradable
coating, is deeper at about a 12 o'clock position when compared to
an engagement at a 6 o'clock position.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 12/986,226 filed on Jan. 7, 2011, the entire
contents of which are hereby incorporated by reference.
BACKGROUND
[0002] The present application relates generally to seals for use
with rotary machines and more particularly relates to a compliant
and an abradable labyrinth sealing system having an elliptical
shape for use with a rotary machine such as a rotary compressor and
the like.
[0003] In a rotary machine, one or more seal generally extend along
an interface between the rotating and the stationary components.
For example, compressors, turbines, and the like may have one or
more seals at the interface between a series of rotating blades or
buckets disposed within a casing or a vane. These seals are
intended to preserve a pressure differential across the rotating
components between upstream and downstream sides thereof. A smaller
clearance dimension at the seal generally increases the performance
of the seal and the efficiency of the overall rotary machine by
limiting the leakage thereacross.
[0004] The seals and the components thereof, however, may be
subject to relatively high temperatures, thermal gradients, and
thermal expansion and contraction during various operational stages
of the rotary machine such as during start-up and during other
types of transient operations. Typically, the seal includes an
extra clearance dimension to reduce the likelihood of contact and
damage between the rotating and the stationary components during
such transient operations. This extra clearance dimension, however,
also may reduce the performance and efficiency of the seal and the
overall rotary machine because of the leakage flow across the seal.
Fluid leakage between the rotor and the casing may lower the
efficiency of the compressor and hence lead to increased fuel
costs.
[0005] There is thus a desire for an improved sealing system for a
rotary machine such as a compressor and the like that reduces
leakage therethrough while maintaining adequate clearance during
transient operations as well as during steady state operating
conditions. Such reduced leakage should improve overall efficiency
while preventing damage to the components herein.
BRIEF DESCRIPTION
[0006] One embodiment of the invention is directed to an elliptical
sealing system for use with a rotor and a stator housing of a
rotary machine. The elliptical sealing system includes a plurality
of sealing segments; and an abradable coating having a uniform
thickness disposed on each of the plurality of sealing segments,
such that the plurality of sealing segments with the abradable
coating disposed thereon has a substantially elliptical shape under
all conditions when the rotor rotates and the rotor remains
stationary.
[0007] Another embodiment of the invention is directed to a rotary
machine. The rotary machine includes a stator housing, a rotor
including a plurality of teeth mounted thereon. The rotary machine
further includes a first semielliptical sealing segment and a
second semielliptical sealing segment mechanically coupled to each
other at about a 3 o'clock position and about a 9 o'clock position.
Each of the first semielliptical sealing segment and the second
semielliptical sealing segment includes an abradable coating of a
uniform thickness disposed thereon. The first semielliptical
sealing segment and the second semielliptical sealing segment with
the abradable coating disposed thereon have an elliptical shape
under all conditions when the rotor rotates and the rotor remains
stationary. The abradable coating has an interference engagement
with the plurality of teeth at about a 12 o'clock position and at
about a 6 o'clock position, and the abradable coating has a line on
line engagement with the plurality of teeth at about the 3 o'clock
position and at about the 9 o'clock position
DRAWINGS
[0008] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings, in which like characters represent like parts throughout
the drawings, wherein:
[0009] FIG. 1 is a schematic view of a rotary machine, in
accordance with one embodiment of the invention;
[0010] FIG. 2 depicts an axial view of a rotor, in accordance with
one embodiment of the invention;
[0011] FIG. 3 depicts an axial view of an elliptical sealing
system, in accordance with one embodiment of the invention;
[0012] FIG. 4 depicts an axial view of a compressor of a gas
turbine engine, in accordance with one embodiment of the
invention;
[0013] FIG. 5 depicts a cross-sectional view of a compressor having
an elliptical sealing system, in accordance with one embodiment of
the invention;
[0014] FIG. 6 depicts an axial view of a compressor when the rotor
120 rotates, in accordance with one embodiment of the invention;
and
[0015] FIG. 7 depicts an axial view of a compressor in a steady
state condition, in accordance with one embodiment of the
invention.
DETAILED DESCRIPTION
[0016] The present disclosure may be best understood with reference
to the figures and detailed description set forth herein. Various
embodiments are discussed below with reference to the figures.
However, those skilled in the art will readily appreciate that the
detailed description given herein with respect to these figures is
just for explanatory purposes as the system extends beyond the
described embodiments.
[0017] Approximating language, as used herein throughout the
specification and claims, may be applied to modify any quantitative
representation that could permissibly vary without resulting in a
change in the basic function to which it is related. Accordingly, a
value modified by a term or terms, such as "about", and
"substantially" is not to be limited to the precise value
specified. Here and throughout the specification and claims, range
limitations may be combined and/or interchanged; such ranges are
identified and include all the sub-ranges contained therein unless
context or language indicates otherwise.
[0018] In the following specification and the claims, the singular
forms "a", "an" and "the" include plural referents unless the
context clearly dictates otherwise. As used herein, the term "or"
is not meant to be exclusive and refers to at least one of the
referenced components being present and includes instances in which
a combination of the referenced components may be present, unless
the context clearly dictates otherwise.
[0019] As used herein, the terms "may" and "may be" indicate a
possibility of an occurrence within a set of circumstances; a
possession of a specified property, characteristic or function;
and/or qualify another verb by expressing one or more of an
ability, capability, or possibility associated with the qualified
verb. Accordingly, usage of "may" and "may be" indicates that a
modified term is apparently appropriate, capable, or suitable for
an indicated capacity, function, or usage, while taking into
account that in some circumstances, the modified term may sometimes
not be appropriate, capable, or suitable.
[0020] FIG. 1 is a schematic view of a rotary machine such as a gas
turbine engine 10, in accordance with one embodiment of the
invention. The gas turbine engine 10 may include a compressor 15.
The compressor 15 compresses an incoming flow of air 20. The
compressor 15 delivers the compressed flow of the air 20 to a
combustor 25. The combustor 25 mixes the compressed flow of the air
20 with a compressed flow of fuel 30 and ignites the mixture to
create a flow of combustion gases 35. Although only a single
combustor 25 is shown, the gas turbine engine 10 may include any
number of combustors. The flow of the combustion gases 35 is
delivered in turn to a turbine 40. The flow of the combustion gases
35 drives the turbine 40 so as to produce mechanical work. The
mechanical work produced in the turbine 40 drives the compressor 15
and an external load 45 such as an electrical generator and the
like.
[0021] The gas turbine engine 10 may use natural gas, various types
of syngas, and/or other types of fuels. The gas turbine engine 10
may be one of any number of different gas turbine engines offered
by General Electric Company of Schenectady, N.Y. and the like. The
gas turbine engine 10 may have other configurations and may use
other types of components. Other types of gas turbine engines also
may be used herein. Multiple gas turbine engines 10, other types of
turbines, and other types of power generation equipment also may be
used herein together. Other types of rotary machines also may be
used herein.
[0022] Gas leakage out of the gas path or into the gas path of the
gas turbine engine 10 from an area of higher pressure to an area of
lower pressure generally is undesirable. As described above, gas
path leakage in the compressor 15 and/or in the turbine 40 may
lower the efficiency of the overall gas turbine engine 10 and lead
to increased fuel costs. The gas turbine engine 10 therefore may
include a sealing system 50 provided in the compressor 15 and/or
the turbine 40. The sealing system 50 facilitates a minimum
clearance between the stationary components and the rotating
components therein. As a result, fluid leakage through these
components may be minimized so as to enhance overall
efficiency.
[0023] FIG. 2 depicts an axial view of a rotor 120, in accordance
with one embodiment of the invention. For example, the rotor 120
may form a part of the compressor 15 or the turbine 40 of the
rotary machine such as the gas turbine engine 10. It is apparent to
a person of ordinary skill in the art that the rotor 120 may also
be implemented in other suitable sections of any other type of
rotary machines without departing from the scope of the present
specification. As depicted in FIG. 2, the rotor 120 may have a
circular shape. The rotor 120 includes a plurality of teeth mounted
thereon. In one example, the plurality of teeth is in a form of
J-strips. A numeral 113 in the axial view of FIG. 2 represents an
area occupied by the plurality of teeth. The area 113 occupied by
the teeth is depicted by a texture having vertical lines. A center
of the rotor 120 is hereinafter also referred to as a rotoric
center 114 which is depicted using + symbol. The rotor 120 may be
mounted on a rotor bearing (not shown) through a rotor journal (not
shown).
[0024] FIG. 3 depicts an axial view of an elliptical sealing system
140, in accordance with one embodiment of the invention. The
elliptical sealing system 140 is similar to the sealing system 50
that may be placed in the rotary machine. As depicted in FIG. 3,
the elliptical sealing system 140 includes a first semielliptical
sealing segment 270 and a second semielliptical sealing segment
280. In one embodiment of the invention, the first semielliptical
sealing segment 270 and the second semielliptical sealing segment
280 may form a packing ring (see FIG. 5). Each of the first
semielliptical sealing segment 270 and the second semielliptical
sealing segment 280 has an abradable coating 170 having uniform
thickness disposed thereon. The abradable coating 170 is shown
using a texture having angled lines.
[0025] The abradable coating 170 may include an alloy of cobalt,
nickel, chromium, aluminum, yttrium, hexagonal boron nitride, and
polymers such as polyesters, polyimides, or the like.
Alternatively, the abradable coating 170 may include nickel,
chromium, aluminum, and clay (bentonite). Further, the abradable
coating 170 may include nickel, graphite, and stainless steel.
Furthermore, the abradable coating 170 may include nickel,
chromium, iron, aluminum, boron and nitrogen. Furthermore, the
abradable coating 170 may also include non-metallic materials
(e.g., polytetrafluoroethylene applied by electrostatic powder
coating process or polytetrafluoroethylene filled synthetic mica
which may be attached by a mechanical device). The abradable
coating 170 may use any desired material in any desired size,
shape, and/or orientation.
[0026] As depicted in FIG. 3, a first end 271 of the first
semielliptical sealing segment 270 is mechanically coupled to a
first end 281 of the second semielliptical sealing segment 280 at
about a 3 o'clock position. Similarly, a second end 272 of the
first semielliptical sealing segment 270 is mechanically coupled to
a second end 282 of the second semielliptical sealing segment 280
at about a 9 o'clock position. Numerals 273 and 274 represent
coupling joints between the first semielliptical sealing segment
270 and the second semielliptical sealing segment 280. In sharp
contrast to traditional designs where a sealing system is formed
using more than two segments, the embodiments of the present
invention are implemented using only two semielliptical sealing
segments such as the first semielliptical sealing segment 270 and
the second semielliptical sealing segment 280.
[0027] The shapes of the first semielliptical sealing segment 270
and the second semielliptical sealing segment 280 are such that
when coupled to each other, the coupling joints 273 and 274 define
a major axis 250 of the elliptical shape of the sealing system 140.
In one embodiment, the length of the major axis 250 is
substantially equal to the outside diameter of the rotor 120
defined by the plurality of teeth mounted on the outer surface of
the rotor 120. Further, as depicted in FIG. 3, the abradable
coating 170 has a uniform thickness. Consequently, an inner surface
of the elliptical sealing system 140 resembles a substantially
elliptical or an elliptical shape under all conditions when the
rotor 120 rotates and the rotor 120 remains stationary (e.g., does
not rotate). By use of the term "elliptical", we also include
various types of hyperboloid, parabaloid, and other types of
similar shapes.
[0028] FIG. 4 depicts an axial view of the compressor 15 of the gas
turbine engine 10, in accordance with one embodiment of the
invention. The axial view of FIG. 4 may be realized when the rotor
120 and the elliptical sealing system 140 are assembled into a
stator housing 130 (depicted using dotted texture) of the
compressor 15. Although, in the embodiment of FIG. 4, the
elliptical sealing system 140 is shown as a part of the compressor
15, the elliptical sealing system 140 may also be implemented in
other suitable components (e.g., the turbine 40) of the gas turbine
engine 10 or any other type of rotary machines without departing
from the scope of the present specification.
[0029] A center of the stator housing 130 is hereinafter also
referred to as a statoric center 115 which is represented by +
symbol. In one embodiment of the invention, the rotor 120 and the
elliptical sealing system 140 are assembled such that the rotoric
center 114 and the statoric center 115 are centrally aligned.
Further, in one embodiment of the invention, the rotor 120 and the
elliptical sealing system 140 are assembled such that the abradable
coating 170 has an interference engagement with the teeth of the
rotor 120 at about the 12 o'clock position and at about the 6
o'clock position, and the abradable coating 170 has a line on line
engagement with the teeth at about the 3 o'clock position and at
about the 9 o'clock position. The term "line on line arrangement"
as used herein refers to providing no engagement between the
abradable coating 170 and the teeth at the 3 o'clock and the 9
o'clock positions such that no end gap is introduced at the 3
o'clock and the 9 o'clock positions. Such line on line engagement
is achieved by designing the rotary machine such that the major
axis 250 of the elliptical sealing system 140 is substantially
equal to the outside diameter of the rotor 120 defined by the
teeth.
[0030] Once assembled, the gas turbine engine 10 may be operated
for about a few seconds or minutes (hereinafter also referred to as
an initial period of rotation). For example, when operated at a
certain speed (e.g., at about 4500 rpm) during the initial period
of rotation, the rotor journal may be lifted-up into the rotor
bearing from its initial position. Consequently, the rotor 120 also
lifts-up and the teeth of the rotor 120. The teeth in turn abrade
the abradable coating 170 defining an elliptical groove (at times
herein referred to as a path) in the abradable coating 170. In one
embodiment of the invention, the teeth of the rotor 120 abrade the
abradable coating 170 at about the 12 o'clock position and at bout
the 6 o'clock position. More particularly, due to the upward lift
of the rotor 120, the teeth abrade more material at about the 12
o'clock position than at about the 6 o'clock position. Further,
since the line on line arrangement is provided at about the 3
o'clock position and at bout the 9 o'clock position, and due to the
upward lift of the rotor 120, no material is abraded from the
abradable coating 170 at about the 3 o'clock position and at about
the 9 o'clock position. Therefore, before the gas turbine engine 10
is implemented for a real-time application/operation the elliptical
path has already been cut/defined in-to the abradable coating
170.
[0031] FIG. 5 depicts a cross-sectional view of the compressor 15
having the elliptical sealing system 140, in accordance with one
embodiment of the invention. The cross-sectional view of the
elliptical sealing system 140 as depicted in FIG. 5 may be realized
at the 12 o'clock position of the axial view of FIG. 4, for
example. The rotor 120 is disposed inside the stator housing 130.
The stator housing 130 may include a number of suction ports and
discharge ports (not shown) communicating fluid to and from the
rotor 120 and the components thereof or otherwise. During rotation
of the rotor 120, an incoming fluid may be sucked through the
suction ports and a compressed fluid may be discharged through the
discharge ports. Other configurations and other components may be
used herein.
[0032] The elliptical sealing system 140 may be positioned between
the rotor 120 and the stator housing 130. The elliptical sealing
system 140 may be configured to control the leakage of the fluid
therethrough without damaging the components thereof. Although
described herein in the context of the compressor, the elliptical
sealing system 140 may be used with any type of rotary machine,
including steam turbines, gas turbines, and the like.
[0033] The elliptical sealing system 140 may include a retractable
packing ring 150 positioned within a slot 160 of the stator housing
130. As noted previously, a packing ring such as the packing ring
150 in its entirety is formed by the first semielliptical sealing
segment 270 and the second semielliptical sealing segment 280. In
the cross-sectional view of FIG. 5, a portion of the packing ring
150 that is visible is a cross-sectional view of the first
semielliptical sealing segment 270 at the 12 o'clock position. The
packing ring 150 may be generally I-shaped although other
configurations may be used herein. The packing ring 150 may include
the abradable coating 170 facing the rotor 120.
[0034] A plurality of biasing members 180 such as springs 190 may
be disposed between the packing ring 150 and the stator housing
130. The biasing members 180 may include leaf springs, coil
springs, helical springs, hydraulic springs, pneumatic springs,
stacked washers, and the like. The biasing members 180 may be
configured to bias the packing ring 150 towards the rotor 120. In
this example, the biasing members 180 may be positioned at about a
12 o'clock position and about a 6 o'clock position. Other positions
may be used herein. Any number or type of biasing members 180 may
be used herein. Other configurations and other components may be
used herein.
[0035] The rotor 120 also may include a plurality teeth 200
(represented by the area 113 in the axial view of FIG. 2) extending
towards the elliptical sealing system 140. In one example, the
teeth 200 may be in the form of a number of "J"-type strips
(alternatively also referred to as J-strips) positioned within a
number of rotor slots 220 on the rotor 120. The J-strips may be
held in place within the rotor slots 220 via a number of wires 230
or other types of connection means. The J-strips may be made of
stainless steel or other types of substantially rigid materials.
Some or all of the J-strips may be in contact with the abradable
coating 170 of the rotor 120. The J-strips may be detachable from
the rotor 120 for replacement if damaged or worn via contact with
the abradable coating 170. Other configurations and other
components may be used herein.
[0036] FIG. 6 depicts an axial view of the compressor 15 when the
rotor 120 rotates (e.g., during the real-time operation), in
accordance with one embodiment of the invention. The elliptical
shape of the sealing system 140 allows for an interference
engagement (represented by an overlapped region of the textures
having vertical and angled lines) between the abradable coating 170
and the teeth of the rotor 120. As depicted in FIG. 6, an
engagement of the teeth of the rotor 120 in the abradable coating
170, is deeper at about a 12 o'clock position when compared to an
engagement at a 6 o'clock position as the rotor 120 lifts upward
during the rotation. Due to the upward lift of the rotor 120, the
rotoric center 114 shifts above the statoric center 115. As the
rotor 120 lifts upward towards the 12 o'clock position, the biasing
member positioned at about the 6 o'clock position is configured to
effect an upward movement of an associated sealing segment (e.g.,
the second semielliptical sealing segment 280). Such upward
movement of the second semielliptical sealing segment 280 at the 6
o'clock position eliminates leakage that may have resulted due to
the lift of the rotor 120.
[0037] FIG. 7 depicts an axial view of the compressor 15 in a
steady state condition, in accordance with one embodiment of the
invention. For example, the steady state condition may refer to a
situation when the rotor 120 is stationary (e.g., not rotating). As
previously noted, the teeth have already abraded some of the
abradable coating 170 during the initial period of rotation. Hence,
when stationary, the rotor 120 rests on the abradable coating 170
such that the rotoric center 114 shifts below the statoric center
115.
[0038] Various advantages that may be realized in the practice of
some embodiments of the invention include, but are not limited to,
improved leakage sealing, improved reliability, and improved
efficiency of the rotary machine. For example, by only using the
two sealing segments, such as, the first semielliptical sealing
segment 270 and the second semielliptical sealing segment 280, no
additional end gap leakage may be introduced through the elliptical
sealing system 140. As noted previously, the traditional designs
include a use of more than two sealing segments. In stark contrast,
embodiments of the present invention utilize only the two sealing
segments. Also, the coupling joints 273 and 274 are made at the
positions (e.g., at about the 3 o'clock position and at about the 9
o'clock position, respectively) where an effect of a force caused
by the lifting of the rotor 120 during rotation is minimum.
Consequently, the possibility of displacement and/or
bending/twisting of the first semielliptical sealing segment 270
and the second semielliptical sealing segment 280 may be
substantially eliminated. This also results in improved
reliability/lifetime of the rotary machine. Moreover, as the
displacement and/or the bending/twisting of the first
semielliptical sealing segment 270 and the second semielliptical
sealing segment 280 may be substantially eliminated, any additional
leakage that may have resulted due to the lifting of the rotor 120
is effectively eliminated. Likewise, the use of the biasing members
180 at about the 12 o'clock position and about at the 6 o'clock
position generally force the elliptical sealing system 140 towards
the teeth of the rotor 120 for contact therewith. Such an adaptive
action by the biasing members 180 also eliminates the leakage.
Reduction/elimination of the leakage leads to an improvement in the
efficiency of the rotary machine.
[0039] It will be appreciated that variants of the above disclosed
and other features and functions, or alternatives thereof, may be
combined to create many other different systems or applications.
Various unanticipated alternatives, modifications, variations, or
improvements therein may be subsequently made by those skilled in
the art and are also intended to be encompassed by the following
claims.
* * * * *