FLEXIBLE SEAL FOR TURBINE ENGINE
A turbine includes a turbine seal. The turbine seal includes a first straight portion extending along a first axis. The turbine seal also includes a second straight portion extending along the first axis. The first and second straight portions of the turbine seal intersect to form a V-shaped cross section with an opening extending along the first axis. The first and second straight portions of the turbine seal are also configured to resiliantly move towards and away from each other and the first and second straight portions of the turbine seal are configured to pre-load the turbine seal along a gap between first and second bucket segments of the turbine.
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The subject matter disclosed herein relates to a flexible seal for use in turbomachinery, such as a turbine engine.
A gas turbine engine combusts a mixture of fuel and air to generate hot combustion gases, which in turn drive one or more turbines. In particular, the hot combustion gases force turbine bucket segments to rotate, thereby driving a shaft to rotate one or more loads, e.g., electrical generator. These turbine bucket segments may include shanks that allow for adjacent placement in a turbine stage of the gas turbine engine. At the same time, highly compressed air is often extracted from a compressor for utilization in pressurizing a cavity formed between two adjacent bucket shanks. This positive pressure difference may aid in preventing hot combustion gases from entering into the shank cavity, thus avoiding increases in thermal stresses that adversely affect bucket life. However, as these bucket segments and their shanks may be individually produced and then combined into a single turbine stage, gaps may be present between the individual turbine bucket shanks. These gaps may provide a leakage path for the pressurized shank cavity air, thus reducing overall turbine efficiency and output. Accordingly, it is desirable to minimize the leakage of this pressurizing gas through gaps located between turbine bucket shanks in a turbine stage of a gas turbine engine.
BRIEF DESCRIPTION OF THE INVENTIONCertain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.
In a first embodiment, a turbine includes a turbine seal including a first straight portion extending along a first axis and a second straight portion extending along the first axis, wherein the first and second straight portions intersect to form a V-shaped cross section with an opening extending along the first axis, wherein the first and second straight portions are configured to resiliantly move towards and away from each other, wherein the first and second straight portions are configured to pre-load the turbine seal along a gap between first and second bucket segments of the turbine
In a second embodiment, a system includes a first turbine segment comprising a first blade coupled to a first shank, a second turbine segment comprising a second blade coupled to a second shank, and a flexible seal disposed in a gap between the first and second shanks, wherein the flexible seal comprises an opening formed by a first straight portion and a second straight portion, the first and second straight portions diverge at an angle away from a vortex, the first and second straight portions are configured to resiliantly move towards and away from each other to vary the width of the opening, and the flexible seal is configured to maintain contact with the first and second turbine segments as a width of the opening varies.
In a third embodiment, a turbine seal includes a first straight portion extending along a first axis, a second straight portion extending along the first axis, wherein the first and second straight portions intersect to form a V-shaped cross section with an opening extending along the first axis, wherein the first and second straight portions are configured to pre-load the turbine seal along a gap between first and second bucket segments of a turbine, a third straight portion coupled to the first straight portion and disposed on a first side of the opening, wherein the third straight portion extends along the first axis, and a fourth straight portion coupled to the second straight portion and disposed on a second side of the opening, wherein the fourth straight portion extends along the first axis, wherein the third straight portion and the fourth straight portion extend in parallel planes along the first axis.
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:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
The present disclosure is directed to a system and a method for sealing a gap between adjacent segments in a turbomachine, such as turbine bucket shanks in a turbine stage of a gas turbine engine, a steam turbine engine, a hydro turbine engine, or another turbine. The system and method may include inserting a flexible seal, such as a flexible seal pin, between adjacent turbine bucket shanks. The preload value (e.g., spring force) of the flexible seal and pressure differentials between the turbine bucket shanks provides a positive seal between any two adjacent bucket shanks. For example, the preload value of the flexible seal provides a positive force by the flexible seal against the adjacent bucket shanks prior to and during operation of the turbomachine (e.g., turbine). The pressure differentials also supplement the positive force of the flexible seal against the adjacent bucket shanks, thereby increasing the effectiveness of the flexible seal. This flexible seal may be, for example, V-shaped or formed in other shapes and may maintain a positive seal despite variations in the gap between adjacent bucket shanks.
The bucket segments 32 may be constructed of a metal, metal alloy, ceramic matrix composite (CMC), or other suitable material. Each bucket segment 32 includes a wheel mount 34, a shank 36, a platform 37, a platform 38, and a bucket or blade 40. When aligned as illustrated in
Additionally, as discussed above, the bucket segments 32 may form a gap 42. This gap 42 may extend radially 31 along the shank 36 from the dovetail of the wheel mount 34 to radially 31 beneath a damper opening 44, which may be located between the adjacent shanks 36 and radially 31 below the airfoil 40 of each of the bucket segments 32. This gap 42 may allow for leakage of hot combustion from an upstream side to a downstream side of the bucket segments 32. Unfortunately, this leakage may reduce the overall efficiency of the turbine engine 10 during use. Accordingly, it may be desirable to block this leakage from occurring through the use of, for example, one or more flexible seals 46 in the gap 42.
Moreover, the V-shaped cross-section 47 of the flexible seal 46 may compress when pressure is applied. Each of the straight portions 49 of the flexible seal 46 may flex when pressure is applied, such that the straight portions 49 may move closer in proximity to one another (thus moving support legs 48 closer to one another as well). For example, due to thermal expansion and/or mechanical load, the shanks 36 may move in a tangential direction, such as direction 35, reducing gap 42. The inverse may also occur when a thermal load is reduced, such that gap 42 may increase. Accordingly, with a change (e.g., reduction) in gap 42, the shank 36 or bucket 32 may apply pressure to the flexible seal 46, causing the flexible seal 46 to move into a cavity (such as a V-shaped cavity) in the bucket 32. Conversely, when gap 42 is increased, the flexible seal 46 may move from a cavity (such as a V-shaped cavity) in the bucket 32. However, regardless of the change in the gap 42, the flexible seal 46 will maintain contact with the bucket 32 adjacent the bucket 32 with the cavity therein to maintain a seal of the gap 42.
In one embodiment, the flexible seal 46 may be made from nickel, cobalt, or iron-base superalloys, or other suitable materials, with desirable mechanical properties able to withstand turbine operating temperatures and conditions (such as 310 stainless steel). Examples of usable superalloys may include Inconel® alloy 600, Inconel® alloy 625, Inconel® alloy 718, Inconel® alloy 738, Inconel® alloy X-750, or Hastalloy® X. The material chosen for the flexible seal 46 may be based on requirements for mechanical strength, creep resistance at high temperatures, corrosion resistance, or other attributes. The flexible seal 46 may be sized such that it fits into the gap 42. An illustration of the flexible seal 46 installed between two bucket segments 32 is illustrated in
As illustrated, the flexible seal 46 under assembly (i.e., cold) conditions may form an angle 62 separating straight portions 49 of the flexible seal. This angle 62 may be approximately, for example, 70 degrees, 75 degrees, 80 degrees, 85 degrees, 90 degrees, 95 degrees, 100 degrees, 105 degrees, 110 degrees, 115 degrees, or more. Moreover, the range of the angle 62 may be between about 60 degrees and about 120 degrees, between about 70 degrees and about 100 degrees, or between about 75 degrees and about 90 degrees. Furthermore, the hollow region 56 may include an angle 64 formed at a connection point of the flat portions 58 and 60. This angle 64 may be approximately, for example, 45%, 50%, 55%, 60%, 56%, 70%, or 75% of the angle 62 of the flexible seal 46.
Furthermore, as illustrated in
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims
1. A turbine, comprising:
- a turbine seal, comprising: a first straight portion extending along a first axis; and a second straight portion extending along the first axis, wherein the first and second straight portions intersect to form a V-shaped cross section with an opening extending along the first axis, wherein the first and second straight portions are configured to resiliantly move towards and away from each other, wherein the first and second straight portions are configured to pre-load the turbine seal along a gap between first and second bucket segments of the turbine.
2. The turbine of claim 1, comprising a third straight portion coupled to the first straight portion and disposed on a first side of the opening, wherein the third straight portion extends along the first axis.
3. The turbine of claim 2, comprising a fourth straight portion coupled to the second straight portion and disposed on a second side of the opening, wherein the fourth straight portion extends along the first axis.
4. The turbine of claim 3, wherein the third straight portion and the fourth straight portion extend in parallel planes along the first axis.
5. The turbine of claim 3, wherein the third straight portion and the fourth straight portion each terminate in a flat tip.
6. The turbine of claim 3, wherein the third straight portion and the fourth straight portion each terminate in a rounded tip.
7. The turbine of claim 1, wherein the turbine seal is configured to mount within a triangular recess in the first bucket segment.
8. The turbine of claim 7, comprising the first bucket segment having the turbine seal disposed in the triangular recess.
9. The turbine of claim 7, wherein the first bucket segment comprises a channel disposed between an upstream side of the first turbine segment and the triangular recess.
10. The turbine of claim 1, wherein the turbine seal comprises material having a first coefficient of thermal expansion that is greater than a second coefficient of thermal expansion of the first and second bucket segments.
11. A system, comprising:
- a first turbine segment comprising a first blade coupled to a first shank;
- a second turbine segment comprising a second blade coupled to a second shank; and
- a flexible seal disposed in a gap between the first and second shanks, wherein the flexible seal comprises an opening formed by a first straight portion and a second straight portion, the first and second straight portions diverge at an angle away from a vortex, the first and second straight portions are configured to resiliantly move towards and away from each other to vary the width of the opening, and the flexible seal is configured to maintain contact with the first and second turbine segments as a width of the opening varies.
12. The system of claim 11, wherein the first straight portion and the second straight portion intersect at the vertex to form a V-shaped cross section.
13. The system of claim 11, wherein the angle between the first and second straight portions varies to maintain contact between the flexible seal and the first and second turbine segments as the width of the opening varies.
14. The system of claim 11, wherein the opening extends along an axis of the flexible seal.
15. The system of claim 11, wherein the flexible seal extends along the gap between the first and second shanks in a radial direction relative to a rotational axis of the first and second turbine segments, and the flexible seal is at least partially disposed in a recess in the first shank.
16. The system of claim 15, wherein the recess comprises a triangular cross-section extending along an axis of the flexible seal.
17. The system of claim 11, wherein the flexible seal comprises a third straight portion coupled to the first straight portion and a fourth straight portion coupled to the second portion.
18. The system of claim 17, wherein the first straight portion and the second straight portion are at least partially disposed in an elongated recess in the first shank and the third straight portion and the fourth straight portion are disposed in the gap.
19. A turbine seal, comprising:
- a first straight portion extending along a first axis;
- a second straight portion extending along the first axis, wherein the first and second straight portions intersect to form an opening extending along the first axis, wherein the first and second straight portions are configured to pre-load the turbine seal along a gap between first and second bucket segments of a turbine;
- a third straight portion coupled to the first straight portion and disposed on a first side of the opening, wherein the third straight portion extends along the first axis; and
- a fourth straight portion coupled to the second straight portion and disposed on a second side of the opening, wherein the fourth straight portion extends along the first axis, wherein the third straight portion and the fourth straight portion extend in parallel planes along the first axis.
20. The turbine seal of claim 19, wherein the opening comprises an angle of between about 70 degrees and about 100 degrees.
Type: Application
Filed: Apr 14, 2011
Publication Date: Oct 18, 2012
Applicant: General Electric Company (Schenectady, NY)
Inventors: Prashant Shukla (Bangalore), Jalindar Appa Walunj (Bangalore), Mark Steven Honkomp (Taylors, SC)
Application Number: 13/087,253
International Classification: F01D 11/08 (20060101);