SPRING-LOADED SEAL ASSEMBLY
A seal assembly is provided. The seal assembly includes a first outer shim and a second outer shim The second outer shim is operably coupled to the first outer shim and comprises at least one substantially impermeable portion that spans across a gap between at least two turbomachine components. The second outer shim further engages the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is either coupled to at least a portion of an outer surface of the first outer shim or comprises an integral portion of the first outer shim The resilient member engages the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
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This application is a continuation-in-part of U.S. patent application No. 13/560,357, entitled “Layered Seal For Turbomachinery,” filed on Jul. 27, 2012, the entire contents of which are hereby incorporated by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENTThis invention was made with Government support under contract number DE-FC26-05NT42643, awarded by the Department Of Energy. The Government has certain rights in the invention.
BACKGROUNDThe invention relates generally to a seal assembly and, more particularly, to seal assemblies for reducing or substantially eliminating leakage in a turbomachine such as a heavy-duty gas turbine or an aero-derivative gas turbine.
A turbomachine has a gas path, which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine area, and a gas outlet (or exhaust nozzle). Leakage of high pressure cooling flows between adjacent stator components in the turbomachine such as shrouds, nozzles, and diaphragms into a low pressure hot gas path may lead to reduced efficiency and may require an increase in burn temperature, and thereby an increase in NOx. Turbine efficiency may thus be improved by reducing or eliminating leakage locations.
Preventing leakage between adjacent stator components with seals may be challenging due to the fact that the seals must be durable enough to withstand several thousand hours of operation and flexible enough to compensate for assembly misalignment, different engaging surfaces, vibration during operation, and unequal thermal expansion between adjacent stator components.
Thus, there is a need to provide a seal assembly to reduce or substantially eliminate leakages between adjacent stator components. It is further desirable that such seals are durable enough to withstand several thousand hours of operation and flexible enough to compensate for assembly misalignment, different engaging surfaces, vibration during operation, and unequal thermal expansion between adjacent stator components.
BRIEF DESCRIPTIONThe inventors of the present application have identified that a through leakage occurs through a gap left under a central metallic shim that does not extend to the bottom of the seal and an end-face leakage occurs through a gap between the ends of the cloth seal and the ends of a mating slot or cavity defined between adjacent stator components in conventional cloth seal embodiments. The use of the combination of a biasing resilient member on the top of a seal assembly and an impermeable outer shim on the bottom of the seal assembly is expected to reduce leakages.
In accordance with one embodiment, a seal assembly is provided. The seal assembly includes a first outer shim and a second outer shim The second outer shim is operably coupled to the first outer shim and comprises at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components. The second outer shim is further configured to engage the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is either coupled to at least a portion of an outer surface of the first outer shim or comprises an integral portion of the first outer shim The resilient member is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components. The resilient member may include a spring that may be configured to push the seal assembly downwards so that the second outer shim maintains a desired contact with the bottom surfaces of the cavity.
In another embodiment a seal assembly is provided. The seal assembly includes an outer shim comprising at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components. The outer shim is further configured to engage the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
In yet another embodiment a turbomachine is provided. The turbomachine includes at least two turbomachine components and a seal assembly disposed in a cavity defined between the at least two turbomachine components. The seal assembly includes a first outer shim and a second outer shim The second outer shim is operably coupled to the first outer shim and comprises at least one substantially impermeable portion configured to span across a gap between the at least two turbomachine components. The second outer shim is further configured to engage the at least two turbomachine components to substantially seal the gap. The substantially impermeable portion is substantially planar at least along a width of the seal assembly. The seal assembly further includes a resilient member that is either coupled to at least a portion of an outer surface of the first outer shim or comprises an integral portion of the first outer shim The resilient member is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
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:
Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms “first”, “second”, and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the terms “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The term “or” is meant to be inclusive and mean one, some, or all of the listed items. The use of terms such as “including,” “comprising,” or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “top,” “bottom,” “side,” “middle,” “outer” and “interior” as used herein are meant to reflect relative, as opposed to absolute positions.
Also, the term “substantial” or “substantially” as used herein is a qualifier term to indicate that the characteristic is present but some deviation is allowed. The amount of allowable deviation can vary depending on the particular context. For example, “substantially planar” indicates a surface or plane is close to being exactly planar, but small deviations are included, for example, either an overall or local deviation of two to five degrees. The term “substantially impermeable” indicates a material that is either completely impervious to movement of any material or composition, or combination of materials or compositions, or reduces leakage to an acceptable limit (for example, in one embodiment, the leakage rate is reduced to half of the leakage rate in existing seals). Also, the term “substantially seal” indicates that the seal is firmly contacted with a surface or plane such that the possibility of leakage is eliminated (that is, leakage is nil) or is reduced to an acceptable limit. Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular seal embodiment may similarly be applied to any other seal embodiment disclosed herein.
Various embodiments of the present invention describe seal assemblies that may be configured for, or used with, any number or type of turbomachine components requiring a seal to reduce or substantially eliminate leakage between the turbomachine components.
As shown in
In some embodiments (not shown), due to manufacturing and assembly limitations or variations, as well as thermal expansion, movement and the like during operation, the first and second recesses 112 and 118 may be skewed, twisted, angled, or otherwise misaligned. In such embodiments, the seal assembly used may be flexible enough to account for such misalignment. For example, above referenced U.S. patent application No. 13/560,357 describes flexible seals to account for such misalignments.
As illustrated in
As shown in
As shown in
Referring still to
Referring again to
In one exemplary embodiment, the resilient member 142 may include, but is not limited to, spring steel or other wear-resistant material capable of withstanding the environment of the turbomachine 100, which the seal assembly 124 may experience. In another exemplary embodiment, the resilient member 142 may include a high-temperature creep resistant material selected from, for example, an austenitic nickel-chromium alloy such as Inconel X-750™, a nickel based alloy such as Rene-41™, or the like. The material of the resilient member 142 may be selected such that it provides flexibility to the resilient member 142 to bend, stretch or compress (and thus may have high tensile strength) to various shapes and sizes. In some embodiments, the resilient member 142 may have a thickness of about 3 mils to about 50 mils.
In some embodiments, a thickness of the seal assembly 124 before being disposed in the cavity may be greater than a thickness “T” of the cavity defined by the first and second recesses 112 and 118. In such embodiments, the thickness of the seal assembly 124 may be reduced during installation in the cavity to a thickness, which may be equal to the thickness T of the cavity, so as to accommodate the seal assembly 124 within the cavity. In such embodiments, the seal assembly 124 may be compressed to fit within the cavity, and thereby may include portions or components configured for such compression. In some embodiments, the compression may be achieved due to flexibility of the resilient member 142, which may be bent, stretched or compressed to any shape or size. For example, U.S. Patent Publication No. 2009/0085305 and U.S. patent application No. 13/306,090 are directed to seals with such “compression fit” features. U.S. patent application No. 13/306,090 is herein incorporated by reference in its entirety.
The first outer shim 126 and the second outer shim 128 may be operably coupled to one another using any known fastening means. In one exemplary embodiment, a weld or a braze may be positioned in a medial portion 162 of the width “W1” of the seal assembly 124. In such embodiments, the weld or braze may be configured to extend along the thickness of the seal assembly 124. Alternatively, in some other embodiments, other types of known fastening means such as an adhesive or a fastener may be used. In embodiments wherein the resilient member 142 and the first outer shim 126 are discrete components, the first outer shim 126, the second outer shim 128, and the resilient member 142 may be similarly operably coupled by any known fastening means, such as, but not limited to, weld, braze, adhesive, or fastener, or any combination thereof. U.S. Patent Publication No. 2009/0085305 and U.S. patent application No. 13/560,357 describe the use of various fastening means to couple various components of a seal assembly.
In various embodiments, the shapes and configurations of the first outer shim, the second outer shim, or the resilient member may vary. Moreover, in some embodiments, the seal assembly may include additional layers. Examples of such variations are provided in
The seal assembly 200 of
The shapes of the first outer shim 126 or the second outer shim 128 or both may vary.
As shown in
As shown in
Due to the addition of the extensions 302, 304, 306 and 308 in the first and second outer shims 126 and 128, increased stiffness may be provided to the overall structure of the seal assembly. Moreover, due to the extensions 302, 304, 306 and 308, any possibility of unwanted material at the edges of the planar portions 134 and 140, for example, because of sharp edges of the planar portions 134 and 140 is avoided.
Referring to
Various embodiments described above for the seal assemblies 100, 200, and 1200 may be equally applied to the seal assembly 300 and seal assemblies of
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Referring to
Alternatively, in another embodiment (not shown), instead of the fourth extension 308, the second extension 304 may be angled from the planar portion 134 such that a bottom surface of the second extension 304 may extend to the horizontal axis X-X′ such that the bottom surface of the second extension 304 may lie on the same plane as defined by the bottom surface 122 of the second recess 118.
Referring to
As illustrated in
Referring to
As described above, the extension of the first and second extensions 302 and 304 to or slightly beyond the bottom surfaces 116 and 122 of the cavity may be helpful to provide additional resistance to the through leakage. Irrespectively, in some embodiments, the end-face and through leakages may be eliminated or substantially reduced using the planar portion 140 of the second outer shim 128 without the first, second, third, and/or fourth extensions 302, 304, 306, 308.
Referring to
The seal assemblies disclosed in accordance with various embodiments of the invention may reduce the leakage between adjacent turbomachine components so as to improve overall system performance and efficiency. Various embodiments of the invention describe the use of the combination of a biasing resilient member (such as 142 or 206) on the top of a seal assembly (such as 124, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, or 1200) and an impermeable outer shim (such as the second outer shim 128) on the bottom of the seal assembly to reduce leakages. A planar portion (such as 140) of the impermeable outer shim may engage with bottom surfaces of a cavity that extends between a first turbomachine component (such as 102) and a second turbomachine component (such as 104) to eliminate or substantially reduce the through and end-face leakages. The impermeable outer shim on the bottom of the seal assembly may also result in reducing other types of leakages such as around leakage that may otherwise occur around the seal assembly. In some exemplary embodiments, the cooling airflow may enter in the area between the impermeable outer shims on top and bottom of the seal assembly; however, the cooling airflow will be blocked by the planar portion (such as 140) of the impermeable outer shim on the bottom from merging with the hot combustion airflow, thereby preventing around leakage.
Moreover, some extensions (302, 304, or any combination thereof) of the impermeable outer shim, for example, to or slightly beyond the bottom surfaces (such as 116 and 122) of the cavity may be helpful to provide additional resistance to the through leakage. Overall leakage rate through the seal assemblies of various embodiments of the invention may be reduced by, for example, thirty percent or more than that achieved using the existing cloth seals. Specifically, various embodiments of the invention may reduce or substantially eliminate end-face and through leakages between adjacent turbomachine components.
Seal assemblies as described in accordance with various embodiments are durable enough to withstand several thousand hours of operation and flexible enough to compensate for assembly misalignment, different engaging surfaces, vibration during operation, and unequal thermal expansion between adjacent stator components. In some embodiments, the resilient member or “spring” may be resilient enough to accommodate vibrations during operation.
While the dimensions and types of materials described herein define the parameters of various embodiments, they are by no means limiting and are merely exemplary. It is to be understood that a skilled artisan will recognize the interchangeability of various features from different embodiments and that the various features described, as well as other known equivalents for each feature, may be mixed and matched by one of ordinary skill in this art to construct additional systems and techniques in accordance with principles of this disclosure. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Claims
1. A seal assembly comprising:
- a first outer shim;
- a second outer shim operably coupled to the first outer shim, wherein the second outer shim comprises at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components and further configured to engage the at least two turbomachine components to substantially seal the gap, wherein the substantially impermeable portion is substantially planar at least along a width of the seal assembly; and
- a resilient member coupled to at least a portion of an outer surface of the first outer shim or comprising an integral portion of the first outer shim, wherein the resilient member is configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
2. The seal assembly of claim 1, wherein the resilient member comprises:
- a substantially planar portion configured to extend at least along the portion of the width of the seal assembly;
- a first arm portion including a first end and a second end; and
- a second arm portion including a first end and a second end, wherein the first end of the first arm portion and the first end of the second arm portion are operably coupled to opposing ends of the substantially planar portion of the resilient member.
3. The seal assembly of claim 2, wherein the second end of the first arm portion and the second end of the second arm portion are operably coupled to top surfaces of the cavity defined between the at least two turbomachine components.
4. The seal assembly of claim 1, further comprising at least one inner layer disposed between the first outer shim and the second outer shim.
5. The seal assembly of claim 4, wherein the at least one inner layer comprises at least one of a wire mesh woven cloth, a flat ribbon mesh woven cloth, a honeycomb structure, a corrugated shim, or a compliant shim.
6. The seal assembly of claim 1, further comprising a first extension and a second extension, operably coupled to opposing end portions of the first outer shim and configured to extend at least along a first portion of a thickness of the seal assembly.
7. The seal assembly of claim 1, further comprising a third extension and a fourth extension, operably coupled to opposing end portions of the second outer shim and configured to extend at least along a second portion of a thickness of the seal assembly.
8. The seal assembly of claim 1, wherein the second outer shim, the resilient member, and the first outer shim are operably coupled by one of a weld or a braze positioned in a medial portion of the width of the seal assembly, the weld or the braze configured to extend along a thickness of the seal assembly.
9. The seal assembly of claim 1, further comprising an adhesive or a fastener for operably coupling the second outer shim, the resilient member, and the first outer shim.
10. The seal assembly of claim 1, wherein the seal assembly is configured to be disposed in the cavity defined between the at least two turbomachine components, wherein the cavity includes a thickness less than a thickness of the seal assembly.
11. The seal assembly of claim 1, wherein the resilient member includes a creep resistant nickel based alloy.
12. The seal assembly of claim 1, wherein at least the first outer shim and the resilient member comprise an integral element.
13. A turbomachine comprising:
- at least two turbomachine components;
- a seal assembly disposed in a cavity defined between the at least two turbomachine components, wherein the seal assembly comprises: a first outer shim; a second outer shim operably coupled to the first outer shim, wherein the second outer shim comprises at least one substantially impermeable portion configured to span across a gap between the at least two turbomachine components, and further configured to engage the at least two turbomachine components to substantially seal the gap, wherein the substantially impermeable portion is substantially planar at least along a width of the seal assembly; and a resilient member coupled to at least a portion of an outer surface of the first outer shim or comprising an integral portion of the first outer shim, wherein the resilient member is configured to engage the seal assembly to contact bottom surfaces of the cavity defined between the at least two turbomachine components.
14. The turbomachine of claim 13, wherein the resilient member comprises:
- a substantially planar portion configured to extend at least along a portion of the width of the seal assembly;
- a first arm portion including a first end and a second end; and
- a second arm portion including a first end and a second end, wherein the first end of the first arm portion and the first end of the second arm portion are operably coupled to opposing ends of the substantially planar portion of the resilient member.
15. The turbomachine of claim 14, wherein the second end of the first arm portion and the second end of the second arm portion are operably coupled to top surfaces of the cavity defined between the at least two turbomachine components.
16. The turbomachine of claim 13, wherein the seal assembly further comprises at least one inner layer disposed between the first outer shim and the second outer shim.
17. The turbomachine of claim 13, wherein the seal assembly further comprises a first extension and a second extension, operably coupled to opposing end portions of the first outer shim and configured to extend at least along a first portion of a thickness of the seal assembly.
18. The turbomachine of claim 13, wherein the seal assembly further comprises a third extension and a fourth extension, operably coupled to opposing end portions of the second outer shim and configured to extend at least along a second portion of a thickness of the seal assembly.
19. A seal assembly comprising:
- an outer shim comprising at least one substantially impermeable portion configured to span across a gap between at least two turbomachine components and further configured to engage the at least two turbomachine components to substantially seal the gap, wherein the substantially impermeable portion is substantially planar at least along a width of the seal assembly; and
- a resilient member configured to engage the seal assembly to contact bottom surfaces of a cavity defined between the at least two turbomachine components.
20. The seal assembly of claim 19, wherein the seal assembly further comprises at least one inner layer disposed between the outer shim and the resilient member.
Type: Application
Filed: Nov 30, 2012
Publication Date: Mar 6, 2014
Applicant: GENERAL ELECTRIC COMPANY (Schenectady, NY)
Inventor: GENERAL ELECTRIC COMPANY
Application Number: 13/690,541
International Classification: F01D 11/00 (20060101);