Background Information Combustion turbines typically include three primary assemblies: a compressor assembly, a combustor assembly, and a turbine assembly. The combustor assembly includes a transition section is disposed adjacent to the turbine assembly. A flow path exists through these assemblies. The turbine assembly is mechanically coupled to the compressor assembly by a central shaft. Typically, an outer casing encloses a plurality of combustor assemblies and transition sections. The combustor assemblies and transition sections are disposed circumferentially about the central shaft.

In operation, the compressor assembly compresses ambient air and directs the compressed air to a plenum created by the outer casing. The plenum surrounds a plurality of combustor assemblies and transition sections. Compressed air within the plenum flows into each combustor assembly. In the combustor assembly, the compressed air is combined with a fuel and ignited, creating a working gas. The working gas passes through a transition section and into the turbine assembly. In the turbine assembly, the working gas is expanded through a series of stationary vanes and rotatable blades which are coupled to the rotatable shaft. As the working gas is expanded through the turbine assembly the gas passing over the rotatable blades creates a rotational force in the shaft. The shaft drives the compressor assembly and may also be coupled to a generator to create electricity.

Each transition section is, essentially, a housing that directs the working gas from a flame zone in a combustor assembly through the plenum to the turbine assembly. Typically, the transition section has a circular cross sectional area adjacent to the flame zone and an annular cross sectional area adjacent to the turbine assembly.

The lateral edge of each transition section engages the lateral edge of the adjacent transition section. A seal, such as a labyrinth seal, may be disposed between the transition section lateral edges. This seal substantially reduces leakage from the plenum through the lateral sides of the transition section into the working gas flow path. The compressed air in the plenum may still, however, escape past the outer and inner edges of the transition section.

Typically, a seal is disposed between each transition section outer and inner edge and the turbine assembly to direct the flow of working gas to the turbine assembly. Prior art seals were typically rigid and made from a material that was about a quarter inch thick. These seals utilized hardware to hold the seal in place. This type of seal permits a load to be transferred from the turbine assembly to the transition section. The service life of the transition section could be improved if it did not have to withstand this load.

Typically, such seals came in a plurality of sections which are attached by hardware to the transition section. To allow for thermal expansion of the seals, the seals did not typically abut each other. When the combustion turbine is in operation, compressed air in the plenum entered the working gas portion of the flow path through the gaps between the seal portions.

These seals typically included a plurality of openings which were in fluid communication with the compressed air in the plenum. Air from the plenum, which is cooler than the working gas, passed through the openings and into the working gas flow path. Initially, the cool air forms a laminar flow, or film cooling, over the seal.

It would be beneficial to have this film of cool air extend over the first row of vanes in the turbine assembly. Due to their thickness, however, prior art seals include a ledge between the seal and the turbine assembly. When the cool gas film and working fluid pass over this ledge, the flow becomes turbulent, mixing the working gas with the cool air and thereby disrupting the cooling film.

There is, therefore, a need for a flexible seal which will not transfer a significant load between the transition section and the turbine assembly.

There is a further need for a seal which does not mechanically attach to either the transition section or the turbine assembly.

There is a further need for a seal which does not allow compressed air in the plenum to enter the working gas flow path through gaps between the seal segments.

There is a further need for a seal which may be easily installed.

There is a further need for a seal which transitions smoothly into the turbine assembly so that a laminar flow which produces film cooling may be maintained into the turbine assembly.

SUMMARY OF THE INVENTION These needs, and others, are satisfied by the invention which provides a flexible, thin sheet seal with interlocking ends on each seal portion. The seal is structured to attach to a transition section and to the turbine assembly without the use of fasteners. Attachment to the transition section is accomplished by an elongated U- shaped section which is sized to have interference fit with a lip at the downstream end of a transition section. Attachment to the turbine assembly is accomplished by a circumferential distal edge. The distal edge is structured to fit within a slot around the peripheral edge of the inner and outer shrouds of the turbine assemblys first row of vanes. The plenum between the compressor assembly and the combustor assembly allows compressed air to flow over the outer surface of the seals. Because the pressure within the plenum is greater than the pressure of the working gas within the transition section, the seal is drawn towards the working gas flow path and is secured against the transition section and turbine assembly by the differential pressure.

The seal may further include a plurality of cooling air openings which allow compressed air from the plenum to enter the flow path just before the first row of vanes in the turbine assembly. Due to the thin structure of the seal, laminar flow may be substantially maintained and allows for effective film cooling for the row one vane shroud.

-The seals further includes a plurality of segments, preferably one segment per transition section, structured to fit around the circumference of the inner and outer edges of a plurality of transition sections and turbine assembly interface. The transition section attachment of one seal segment will engage the transition section attachment of an adjacent seal segment. The first seal segment will have an end with a bendable, extended tab. The other end of the seal includes an integral segment gap -seal. The-segment gap-seal-is disposed on the plenum side of-the-seal segment. The segment gap seal extends past one end of the seal segment and overlays the seal segment. Thus, when the ends of two adjacent seal segments are brought into contact with each other, the segment gap seal overlays the interface between the seal segments. The segment gap seal are manufactured as a separate structure and attached, e. g., by welding, brazing, or otherwise adhering, the segment gap seal to the seal segment. An interlock notch structured to cooperate with the bendable tab is formed in the segment gap seal. Thus, during assembly, the installer is presented with a plurality of identical seal segments. These seal segments do not require any extra hardware to install the seals.

Alternatively, the seal segments may be formed with integral gap seals. IN this embodiment, a seal will have an end with a notch. When the seal segments are placed in an overlapping relation, the tab of an adjacent seal may be bent to engage the notch, thereby interlocking the seals segments. The notch has a greater width than the tab, thus the seal segments may slide in response to thermal expansion.

BRIEF DESCRIPTION OF THE DRAWINGS A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which : Figure 1 is a cross sectional view of a combustion turbine.

Figure 2 is a schematic view of a combustor assembly, transition section, and turbine assembly.

Figure 2A is a detail view of the outer seal.

Figure 3 is a view of a seal segment.

Figures 3A and 3B are detailed views of the seal segment ends.

Figure 4 is a cross-sectional view of a seal assembly at the segment gap seal.

Figures 5A, and 5B, are each a cross-sectional view of an alternate embodiment of the seal assembly.

Figures 6A, 6B, and 6C are a cross-sectional views of an alternate embodiment of the seal assembly.

DETAILED DESCRIPTION OF THE EMBODIMENTS As used-herein, flexible means the ability of a seal to elastically deform and --return, generally, to the seals-original shape.

As is well known in the art and shown in Fig. 1, a combustion turbine 1 includes a compressor assembly 2, a combustor assembly 3, a transition section 10, and a turbine assembly 20. A flow path exists through the compressor assembly, combustor assembly 3, transition section 10, and turbine assembly 20. The turbine assembly 20 is mechanically coupled to the compressor assembly 2 by a central shaft 4. Typically, an outer casing 9 fonns a plenum 8 and encloses a plurality of combustor assemblies 3 and transition sections 10. The combustor assemblies 3 and transition sections 10 are disposed circumferentially about the central shaft 4.

In operation, the compressor assembly 2 inducts ambient air and compresses it. The compressed air travels through the flow path to a plenum 8 defined by casing 9. The pressure of the compressed air in plenum 8 is greater than the pressure in the flow path within the transition section 10. Compressed air in the plenum 8 enters a combustor assembly 3 where the compressed air is mixed with a fuel and ignited to create a working gas. The working gas passes from the combustor assembly 3 through the transition section 10 and into the turbine assembly 20. In the turbine assembly 20, the working gas is expanded through a series of rotatable blades 21, which are attached to shaft 4, and stationary vanes 22. As the working gas passes through the turbine assembly 20, the blades 21 and shaft 4 rotate creating a mechanical force. The shaft 4 may be coupled to a generator to produce electricity.

As shown in Figure 2 and 2A, the transition section 10 includes a housing 11 with a downstream end 11A that has an annular cross section. The lateral sides (not shown) of each-transition section housing 11 contacts the lateral side of an adjacent transition section at the downstream end 11A. The housing downstream end 11A -includes a outer member 12 and an inner member 14. Both the outer member 12 and the inner member 14 have a generally perpendicular lip, 13,15, respectively, at the end of the housing 11. Outer lip 13 extends from outer member 12 towards casing 9.

Inner lip 15 extends from inner member 14 towards shaft 4. Outer lip 13 is integral to outer member 12. Inner lip 15 is integral to inner member 14.

Turbine assembly 20 includes a plurality of stationary vane assemblies 22. In a turbine assembly 20 having multiple rows of vanes, the most upstream row of vanes is identified as row one. A vane 22 in row one includes an air foil body portion 24, --and an-outer-shroud-26,-and an--inner shroud 28:--Both the outer shroud 26 and the inner shroud 28 have leading edges 27,29, respectively, adjacent to transition section 10. When a plurality of vanes 22 are assembled into a first row within the turbine assembly 20, there is a segmented leading edge which circumscribes shaft 4. As shown in figure 2A, the outer shroud leading edge 27 includes a slot 30. Slot 30 extends into the outer shroud leading edge 27. A similar slot 32 can be found on the inner shroud leading edge 29 as well.

A gap exists between the vane assemblies 22 and both transition section outer member 12 and inner member 14. A seal assembly 39 having an outer seal 40 and an inner seal 50, are disposed between the transition section housing 11 and the turbine assembly 20 to channel the working fluid to turbine assembly 20. The seals 40,50 generally have corresponding structures, except that the inner seal 50 is structured to have a smaller radius. Outer seal 40 is shown in Fig 2A. It is understood that the inner seal 50 has the same parts as those identified on the outer seal 40 in Fig. 2A.

Outer seal 40 includes a transition section attachment end 42, a flexible seal body 44, and a turbine assembly attachment end 46. The seal body 44 has a first end 44A and a second end 44B. Preferably, the seal body 44 has a thickness of less than about 0.200 inch (0.508 cm). The transition section attachment end 42 is integral to seal body first end 44A, and a turbine assembly attachment end 46 is integral to seal body second end 44B. Inner seal 50, shown in Fig. 2, includes a transition section attachment end 52, a flexible seal body 54, and a turbine assembly attachment end 56. Each seal 40, 50 has an inside 41A, 51A and an outside 41B, 51B. The seal inside 41A, 51A is located-adjacent to the working gas flow within the flow path. The seal outside 41B, 51B is located adjacent to the compressed air flow within plenum 8.

As shown in Fig. 2A, the transition section attachment end 42 is structured as an elongated U-shaped member which extends generally perpendicular from seal body 44. Turbine assembly attachment end 46 is structured as a C-shaped member which opens in a direction parallel to seal body 44. When installed in the gap between transition section 10 and turbine assembly 20, the transition section attaclunent end 42 is placed over lip 13. The distal end of turbine assembly attachment end 46 is disposed within slot 30 on the outer shroud leading edge 27. In the preferred embodiment, the turbine assembly attachment end 46 includes a C- -shaped-member 47. The C-shaped member 47 has an inner leg 48 and an outer leg 49. The C-shaped member opens in a direction generally parallel to the shaft 4 and towards the turbine assembly 20. The inner leg 48 of the C-shaped member 47 is attached to the seal body 44. The outer leg 49 has a distal end 49a that is structured to fit within slot 30. The C-shaped member is sized to space seal body 44 away from vane leading edge 27. The inner leg 48 attached to the seal body 44 has a distal end 48a that is angled. The distal end of seal body 44 may also be angled. The angled distal end 48a is shaped to correspond to the shape of the outer shroud leading edge 27. As will be described below, the angled distal end 48a and outer shroud leading edge 27 form a channel for cooling air to pass through. The seal body 44 substantially fills the gap between the transition section 10 and the turbine assembly 20.

As shown in Figure 2A, a plurality of openings 79 are located on seal body 44, 54 and on turbine assembly attachment ends 46,56. The openings 79 extend between plenum 8 and the flow path within the transition section 10 and allow fluid communication therebetween.

As shown in Figure 3, the outer seal 40 and the inner seal 50 are formed from segments 60,70 that extend along an arc having the combustion turbine centerline as a center. As shown in Figures 3A and 3B, the segments 60,70 have a first end 62, 72 and second ends 64,74, respectively, which are structured to interlock with an adjacent segment 60,70. Between the interlocking ends, 62,64 or 72,74, a gap exists.

This gap is beneficial as it allows for thermal expansion of the segments 60,70. The gap, however, also allows-compressed air from plenum 8 to flow into the working gas flow path. The interlock is structured to reduce the flow of gas through the gap.

As shown in Figure 3A, outer seal segment first end 62 includes a tab 63 on the distal end of transition section attachment end 42. Outer segment tab 63 is structured to be bendable. As shown on Figure 4, a segment gap seal 80 is coupled, e. g., by welding, brazing, or otherwise adhering, the segment gap seal onto a seal segment second end 64,74. The segment gap seal 80 includes a transition section attachment end 82, a body portion 84 and a extension 86. The segment gap seal forms part of the interlock by having a notch 65,75. The segment gap seal 80 is attached to the~seal segment second-end 64, 74 so that a-portion of the segment gap seal 80 extends beyond the seal segment second end 64,74. The extension 86 is structured to fit against outer seal turbine assembly attachment end 46 or inner turbine assembly attachment end 56. Thus, when a seal segment first end 62,72 is placed adjacent to a seal segment second end 64,74, the seal segment ends 62,72,64 and 74 are disposed below the segment gap seal 80 and extension 86 abuts outer seal turbine assembly attachment end 46 or inner turbine assembly attachment end 56.

Alternatively, the outer seal segment second end 64,74 may include an integral gap seal like structure. In this embodiment the seal segment second end 64, 74 includes a notch 65 on the distal end of transition section attachment end 46,56.

Similarly, as shown in Figure 3B, inner seal first and second ends 72,74 have a tab 73 and notch 75. The tabs 63,73 are narrower than the respective notches 65,75. Outer and inner seal second ends 64,74 also have a cutout 66,76 in the turbine assembly attachment ends 46,56. The cutout, as will be explained below, is structured to allow the first ends 62,72 and second ends 64,74 to abut each other at the turbine assembly attachment ends 46,56, and overlay each other at the transition section attachment ends 42,52.

To assemble the outer seal 40 a plurality of seal segments 60 sufficient to form about a 360 degree arc are used. At least one transition section 10 of the plurality of transition sections is not installed. At a transition section 10 adjacent to the removed transition section 10, the transition section attachment end 42 of one segment 60 is placed over the edge of transition section lip 13 and the distal end of C-shaped member leg 49 is aligned with slot 30. The seal segment 60 is then installed by sliding the seal segment 60 into place on the transition section 10. The seal segment may be slid around the plurality of transition sections 10 to a final position. The adjacent seal segment 60 is then installed in a similar mamler. As shown in Figure 4, the interlocking ends 62,64 are then joined by overlapping the segment gap seal 80 located at outer seal segment second end 64 of the first installed seal segment 60 over outer seal segment first end 62 of the second installed seal segment.. The outer seal tab 63 on the first segment 60 will be positioned adjacent to notch 65 segment gap seal 80. The turbine assembly attachment ends 46 of the adjacent outer segments 60 will abut each other, with the turbine assembly attachment end 46 of the first outer seal segment 60 disposed below the portion of the segment gap seal 80 that extend beyond the seal segment second end 64. The tab 63 of the first outer seal segment 60 is then bent about 180 degrees over notch 65 of the second outer seal segment 60.

Thus, the seals are interlocked with each other, and not fixedly attached to either the transition section 10 or the turbine assembly 20. Additional outer seal segments 60 are installed and interlocked until the seal 40 extends about the entire transition section 10 and turbine assembly 20 interface. The inner seal 50 is then installed in a similar fashion. The last outer seal segment 60 and inner seal segment 70 to be installed are placed on the transition section 10 that is not installed. As the transition section 10 is installed, the last outer seal segment 60 and inner seal segment 70 will be disposed adjacent to seal segments 60,70 on either side. The last seal segments 60, 70 are then interlocked to the adjacent seal segment 60,70.

In operation, the working gas passing through the transition section 10 and the turbine assembly 20 on the seal inside 41A, 51A is at a lower pressure than the compressed air on the seal outside 41B, 51B within plenum 8. As such, the differential pressure draws the seals 40,50 towards the flow path of the working gas.

The pressure biases the transition section attachment ends 42,52 against lips 13,15 respectively. The outer leg 49 of the seal turbine attachment end 46 is biased against slot 30. A small amount of compressed air passes through openings 79 on the seal body 44 creates a cooling film on the inner side of seals 40,50. An opening on the turbine assembly attachment end 46 allows air to flow between the angled distal end 48a and the outer shroud leading edge 27, thereby forming a cooling film on the outer shroud 26.

As shown in Figure 5A, an alternate seal body 44 may be structured to have a bellows portion 90 to allow the seal body to have an enhanced flexing capability. As shown in Figure 5B, enhanced flexibility may also be achieved using an annular ridge 91 extending along the seal body 44.

As shown in Figures 6A and 6B, in another alternate embodiment the seals 140,150 have transition section attachment ends 142,152 with an upstream side 142a, 152a and a downstream side 142b, 152b. The transition section attachment end upstream sides 142a, 152a are structured to be biased against the upstream side of the inner and outer lips 13,15. By biasing the transition section attachment end upstream sides 142a, 152a against the upstream side of the inner and outer lips 13,15, the seal -is-shifted toward-the vane assembly 22. This allows-the-transition section-attachment end downstream sides 142b, 152b to be spaced apart form the inner and outer lips 13, 15. When configured in this manner, transition section attachment ends 142,152 may flex, thereby giving the seals 140,150 enhanced flexibility. The biasing means 120 may be a coil spring 122 (Fig. 6A) or a fastener 124 (Fig. 6B), such as a bolt or screw.

Alternatively, as shown in Figure 6C, transition section attachment end downstream side 142b may be spaced apart from the lip 13 incorporating an annular groove 92 in lip 13 and inserting transition section attachment end upstream side 142a into the groove.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. For example, as described above, the outer lip 13 and timer lip 15 are part of the transition section 10 while the outer shroud slot 30 and inner shroud slot 32 are part of the turbine assembly 20. Those skilled in the art can see that the lips could be structured as part of the turbine assembly 20 while the slots could be part of the transition section 10. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.