CA2031085A1

CA2031085A1 - Arrangement for sealing gaps between adjacent circumferential segments of turbine nozzles and shrouds

Info

Publication number: CA2031085A1
Application number: CA002031085A
Authority: CA
Inventors: Michael P. Hagle
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1990-01-16
Filing date: 1990-11-29
Publication date: 1991-07-17
Also published as: FR2657119A1; GB2240822A; GB9100790D0; DE4100554A1; JPH06102989B2; ITMI910079A1; JPH04214932A; IT1267127B1; ITMI910079A0

Abstract

IMPROVED ARRANGEMENT FOR SEALING GAPS BETWEEN ADJACENT
CIRCUMFERENTIAL SEGMENTS OF TURBINE NOZZLES AND SHROUDS

ABSTRACT OF THE DISCLOSURE

An arrangement for sealing a gap defined between spaced edges on a pair of adjacent segments includes a pair of oppositely inclined flanges on the segment edges having respective oppositely inclined planar surfaces defined thereon, an elongated cylindrical seal rod disposed between and seated on the spaced inclined planar surfaces of the edge flanges so as to span and close the gap between the edge flanges, and a yieldable resilient spring clip having a channel-like cross-sectional configuration. The spring clip is anchored under the edge flanges and overlies the seal rod so as to bias the seal rod into sealing contact with the planar surfaces of the edge flanges and a sealing relationship with the gap.
Opposite edge portions of the spring clip have hook-like configurations one being the reverse of the other for extending around and under the edge flanges, whereas a middle portion of the spring clip is engaged with the seal rod and configured in its shape to conform to the shape of a side of the seal rod engaged by the clip middle portion.

Description

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IMPROVED ARRANGEMENT FOR SEALING GAPS BETWEEN ADJACENT
CIRCUMFERENTIAL SEGMENTS OF TURBINE NOZZLES AND SHROUDS

Field of the Invention The present invention relates generally to gas turbine engines and, more particularly, to an improved arrangement for sealing gaps between adjacent circumferential segments of turbine nozzles and shrouds.

Description of the Prior Art The efficiency of a gas turbine engine is dependent upon many factors. One factor is the degree to which high pressure coolant air generated by a compressor section of the gas turbine engine and intended primarily for driving a turbine section of the engine is siphoned off to other uses in the engine. One such~use of the air is for cooling metal surfaces along the main core fIowpath to maintain them below melting temperature. The greater the amount of coolant air diverted to oth~r uses in the engine, the less the amount of air to drive the turbine~ and thus the less efficiéntly the turbine wil~l operate. ; ~
Therefore, it is~important to limit the quantity of coolant air diverted from use in driving the turbine to 2~3~

only the amount absolutely needed to perform such other ancillary functions. Sealing arrangements have been proposed in the prior art to prevent ~oss of such diverted air by leakage through gaps between adjacent segments of engine components. Representative of the prior art are the sealing arrangements disclosed in U.S.
Patents to Bertelson (3,728,041), Kildea (4,311,432), Grosjean (4,537,024), ~olowach et al (4,~62,658), Miraucourt et al (4,759,687) and Clevenger et al (4,767,260).
One prior ar~ sealing arrangement used frequently for sealing a gap between adjacent segment ~dges of turbine nozzles and shrouds is known as a splin~ seal arrangement. An advantage of this arrangement is its simple construction. However, it provides an inefficient sealing mechanism since it is susceptible to leakage whenever less than optimum geometry exists at the segment edges, such as resulting from the machining methods used, the tolerances employed, and misaligning movement of the segments relative to each other.
Consequently, a need still remains for an arran~ement ~or effectively sealing segment edge gaps while avoiding the above-described problems.

SUMMARY OF THE INVENTION

The present invention provides an improved sealing arrangement designed to satisfy the afore~entioned needs.
The improved sealing arrangement of the present invention functions to maintain an effective seal across a gap between adjacent segment edges concurrently as the segment edges undergo limited movement and misalignment relative to one another. Given such capabilities~ the improved sealing arrangement is particularly suited to seal gaps between adjacent segments of turbine nozzles and shrouds where such relative movements and misalignments will occur due to thermal expansion and 2~ 0~

contraction of the segments.
The sealing arrangement is thus ~ffective in preventing leakage of coolant air through the gaps and into a main core flowpath of the gas turbine engine. The present invention applies to all turbine engines that employ cooled segmented nozzles and shrouds. Turbine engine efficiency is increased by the enhanced coolant sealing performance of the improved sealing arrangement of the present invention. Also, the improved sealing arrangement provides better wear characteristics and improved cooling of segment edges.
Accordingly, the present invention is directed to an improved arrangement for sealing a gap between adjacent edges of segmented components which comprises: ~a) a pair of oppositely inclined flanges on the segment edges having respective oppositely inclined planar surfaces defined thereon; (b) a seal member disposed between and seated on the inclined planar surfaces of the flanges so as to span and close the gap between the flanges; and (c) a yieldable resilient spring clip anchored under the flanges and overlying the seal member so as to bias the seal member into sealing contact with the planar surfaces of flanges and a sealing relationship with the gap.
More particularly, the spring clip has a channel-like cross-sectional configuration and includes a pair of opposite longitudinal edge portions and a middle portion interconnecting the opposite edge portions. The opposite edge portions of the spring clip have hook-lik~
configurations, one being the reverse of the other, for extending around and under the edges of the segmented components~ The middle portion of the clip overlies and is engaged with~the seal member and is configured in its shape to conform to the shape of a side of the seal member which is engaged by the clip middle portion.
Further, the seal member is an elongated linear rod having rounded surface portions engaged with the planar surfaces of the segment edge flanges. Specifically, the ~3~ 5 sea? rod has a circular cross~sectional configuration for making substantially line sealing contact with the planar surfaces of the flanges.
These and other features and advantaqes and ~ttainments of the present invention will become apparent to those skilled in the art upon a reading o~ the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.
B~IEF DESCRIPTION OF THE DRAWINGS

In the course of the following detailed description, reference will be made to the attached drawings in which:
Fig. 1 is a schematic view of a gas turbine engine.
Fig. 2 is a fragmentary cross-sectional view of a prior art sealing arrangement for sealing gaps between adjacent circumferential segments of turbine nozzles and shrouds.
Fig. 3 is a fragmentary perspective view of an improved sealing arrangement in accordance with the present invention.
Fig. ~ is an enlarged end view of the improved sealing arrangement of Fig. 3.
DETAILED DESCRIPTION OF THE INVENTION

In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as "forward", "rearward", "le~t'~ right~', "upwar~ly", lldQwllwardlyll r and the like, are words of convenien e and are not to be construed as limiting terms.

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-5- l~DV-9733 In General Referring now to the drawings, and particularly to Fig. 1, there is illustrated a gas turbine engine, generally designated lo, to which the present invention can ~e applied. The engine 10 has a longitudinal center line or axis A and an annular casing 12 disposed coaxially and concentrically about the axis A. The engine 10 includes a core gas generator engine 14 which is composed of a compressor 16, a combustor 18~ and a high pressure turbine 20, either single or multiple stage, all arranged coaxially about the longitudinal axis or center line A of the engine lo in a serial, axial flow relationship. An annular drive shaft 22 fixedly interconnects the compressor 16 and high pressure turbine 20.
The core engine 14 is effective for generating combustion gases. Pressurized air from the compressor 16 is mixed with fuel in the combustor 18 and ignited, thereby generating combustion gases. Some work is extracted from these gases by the high pressure turbine 20 which drives the compressor 16. The remainder of the combustion gases are discharged from the core engine 14 into a low pressure power turbine 24.
The low pressure turbine 24 includes an annular drum rotor 26 and a stator 28. The rotor 26 is rotatably mounted by suitable bearings 30 and includes a plurality of turbine blade rows 34 extending radially outwardly therefrom and axially spaced. The stator 28 is disposed radially outwardly of the rotor 26 and has a plurality of stator vane rows 36 fixedly attached to and extending radially inwardly from the stationary casing 12. The stator vane rows 36 are axially spaced so as to alternate with the turbine blade rows 34. The ro~or 26 is fixedly attached to a drive shaft 38 and interconnected to the drive shaft 22 via differential bearings 32.
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The drive shaft 38, in turn, rotatably drives a forward booster rotor 39 which ~orms part of a booster compressor 40 and which also supports forward fan blade rows 41 that are housed within a nacelle 42 supported about the stationary casing 12 by a plurality of struts 43, only. one of which is shown. The booster compressor 40 is comprised of a plurality of booster blade rows 44 ~ixedly attached to and extending radially outwardly from the boos~er rotor 39 for rotation therewith and a plurality of booster stator vane rows 46 fixedly attached to and extending radially inwardly from the stationary casing 12. Both the booster blade rows 44 and the stator vane rows 46 are axially spaced and so arranged to alternate with one another.
Sealing Arranqement of the Prior Art Referring now to Fig. 2, there is illustrated a frequently used prior art sealing arrangement, generally designated 48 and referred to hereinafter as the spline seal arrangement, for preventing leakage of cooIant air from an exterior coolant side 14A to an interior flowpath side 14B of the core engine 14. The spline seal arrangement ~48 is provided for sealing each o~ a plurality of gaps 50 (only one being shown) between adjacent edges 52 of a plurality of circumferential segments 54 (only a; pair of which are shown) comprising parts of no2zles and shrouds (not fully shown) of the gas turbine engine 10.
The gaps 50 provide a path far leakage of coolant air from the higher pressure exterior side 14A to the lower pressure interior side 14B of the core engine I4. The coolant air is typically routed at low velocity and und~er high pressure against impingement baffles 5~ overlying the seg~ents 54 desired to ke cooled. As the air goes throuqh orifices 58 in the baffles, it accelerates and impingPs on the exterior side :of the segments 54 at 2~3~

higher velocity which increases the transfer of heat from the seqments.
For preventiny the coolant air from leaking through the gap 50, the spline seal arrangement 48 employs an elongated thin flat spline seal member 60. The spline seal member 60 is inserted along its opposite longitudinal edges 60A into grooves 62 defined in the adjacent segment edges 52 so as to span the gap 50 between the edges and seal against the lower surfaces 62A
of the grooves 62.
However, due to inability to assure a common planar relationship between the grooves 62 of the adjacent segment edges 52, the spline seal arrangement 48 provides an ineffective sealing arrangement susceptible to leakage. The inability to maintain alignment of the adjacent grooves 62 in the same plane is due to machining tolerances and segment movements. The spline seal member 60 thus will not seat and seal properly in the grooves 62 and, as a result, will provide a leak path. Also, the spline seal grooves 6~ are typically produced by an electric discharge machining method which provides a roughness on the groove surfaces, including lower surfaces 62A against which the flat seal member 60 contacts and is seated. The roug~ness of the lower surfaces 6~A thus contributes to the leak path for coolant air.
The spline seal arrangement 48 also provides a geometry at the segment edges 52 that is difficult to cool efficiently. Because of this cooling difficulty and the increases in turbine operating temperatures, the segment edges 52 are susceptible to oxidation erosion.
Modifications to the prior ar~ spline seal arrangement to improved segment edge cooling is restricted by the inherent seal geometry.

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Improved Sealinq Arrangement of Present Invention Turning now to Figs. 3 and 4, there is illustrated an improved sealing arrangement, generally designated 64, constructed in accordance with the present invention which avoids the above-described problems associated with the prior art spline sealing arrangement 48. The improvPd sealing arrangement 64 includes a pair of oppositely inclined flanges 66 on the edges 52 of the circumferential segments 54 being normally spaced apart by the gap 50. The flanges 66, in turn, define respective, generally equally, oppositely inclined planar upwardly-facing surfaces 68 thereon.
The sealing arrangement 64 also includes a seal lS member 70 preferably in the form of an elongated generally linearly-extending cylindrical rod 70. The cylindrical seal rod 70 is disposed between and seated on the oppositely inclined planar surfaces 68 of the inclined flanges 66 so as to span and close the gap 50 between the flanges 66. The circular cross-sectional configuration of the rod 70 and the oppositely inclined orientation of the planar surfac.es 68 promotes a line sealing contact between spaced curved surface portions 70A of the rod 70 and the planar surfaces 68.
The sealing arrangement 64 further includes a yieldable resilient spring clip 72 anchored under the flanges 66 and overlying the seaI rod 70 so as to bias the rod into sealing line contact with the planar surfaces 68 of the flanges ~6 and into a sealing relationship across and with the gap 50. Also in Fig. 3, there is illustrated coolant air impingement plates 74 (the holes therein being omitted for clarity~ which do not form part of the sealing arrangemen~ 64 of~ the present invention.
The spring 51ip 72 has a channel-like cross-sPctional configuration~ and includes a pair of opposite longitudinal edge portions 72A and a mlddle~portion 7ZB

' .

2~3~5 -9~ 13DV-9733 interconnecting the opposite edge portions 72A~ As seen in Fig. 4, the opposite longitudinal edge poxtions 72A of the spring clip 72 have generally hook-like configurations, one being the reverse of the other. The hook-like edge portions 72A extend around and under the edge flanges 66 of the segments 54 and makP contact with the underside surfaces 69 of the flanges 66 at the terminal ends of the edge portions 72A for anchoring the spring clip 72 thereto. The underside surfaces 69 are substantially planar also and substantially parallel to the upper planar surfaces 68.
The middle portion 72B of the clip 72 overlies and is engaged with top side of the cylindrical seal rod 70.
The clip middle portion 72B is arcuately shaped in cross-section to conform to the curved shape of the top side of the seal rod 70 where contact is made with the rod. The spring clip 72 flexes relatively easily and is of relatively low stiffness so that it imposes only a light loading or bias on the seal rod 70.
The flexibility of the spring clip 72 retains the seal rod 70 in the crevice formed by the generally equally and oppositely inclined planar surfaces 68 on the flanges 66. The sealing arrangement is maintained relatively evenly as the flanges move relative to one another due to the fact that the planes of the surfaces 68 will always intersect under engine operating conditions. Therefore, the segments 54 are free to move radially or circumferentially apart or angularly, and the sealing arrangement functions the same as if perfect alignment is maintained. The downward bias of the clip 72 on the rod 70 permits the rod to ride up and down on the flanges 66.as they move respectively closer to and further from one another, causing the gap 50 to ~ecome respectively narrower and wider. The clip edge portions 72A may be slidingly or fixedly retained to the underside surface 69 of the flanges 6~, depending on expect~d operating conditions, and still maintaln the sealin~

2 ~ 3.~

-lO- 13DV-9733 arrangement.
It should be apparent that he spring clip 72 and seal rod 70 need not be of the same length. The spring clip 72 can be made up of shorter lengths. Further, the cross-sectional configuration of the clip can be altered to provide various amounts of seal actuation force.
Also, the sealing surfaces of the flanges 66 can be manufactured by grinding thereby providing a smoother surface finish for better sealing and one that is less costly to produce. The ends of the spring clip can be capped to prevent air leakage there.
It is thought that the present invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the forms hereinbefore described being merely preferred or exemplary embodiments thereof. For example, the invention will seal, or can be easily adapted to seal, the gap between any adjacent segments, not just circumferential segments.

Claims

1. An assembly for sealing a gap between adjacent edges on segmented components having oppositely inclined planar surfaces thereon, said sealing arrangement comprising:
(a) a seal member disposed between and seated on the inclined planar surfaces of the edges of the segmented components so as to span and close the gap between the edges; and (b) a yieldable resilient spring clip anchored under the edges of the segmented components and overlying said seal member so as to bias said seal member into sealing contact with the planar surfaces of edges and a sealing relationship with the gap.

2. The arrangement as recited in Claim 1, wherein said segmented components comprise circumferentially segmented components and said spring clip has a pair of opposite longitudinal edge portions and a middle portion interconnecting said opposite edge portions.

3. The arrangement as recited in Claim 2, wherein said opposite edge portions of said spring clip have hook-like configurations one being the reverse of the other for extending around and under the edges of the segmented components.

4. The arrangement as recited in Claim 2, wherein said middle portion of said clip is engaged with said seal member and shaped in conformance with the shape of a side of said seal member engaged by said clip middle portion.

5. The arrangement as recited in Claim 1, wherein said seal member is an elongated linear rod having rounded surface portions engaged with the planar surfaces of the edges.

6. The arrangement as recited in Claim 5. wherein said seal rod has a circular cross-sectional configuration for making substantially line sealing contact with the planar surfaces of the edges.

7. The arrangement as recited in Claim 1, wherein said spring clip has a channel-like cross-sectional configuration.

8. In combination with a pair of spaced apart adjacent segments having spaced edges defining a gap therebetween, a sealing arrangement comprising:
(a) a pair of flanges on said edges of said segments having respective oppositely inclined planar surfaces defined thereon;
(b) a seal member disposed between said edge flanges and seated on said oppositely inclined planar surfaces thereon so as to span and sealably close the gap between the edges; and (c) a yieldable resilient spring clip anchored under said edge flanges and overlying said seal member so as to bias said seal member into sealing contact with said planar surfaces of edge flanges and a sealing relationship with said gap.

9. The arrangement as recited in Claim 8, wherein said spring clip has a pair of opposite longitudinal edge portions and a middle portion interconnecting said opposite edge portions.

10. The arrangement as recited in Claim 9, wherein said opposite edge portions of said spring clip have hook-like configurations, one being the reverse of the other for extending around and under the edges of the segmented components.

11. The arrangement as recited in Claim 9, wherein said middle portion of said clip is engaged with said seal member and shaped in conformance with the shape of a side of said seal member engaged by said clip middle portion.

12. The arrangement as recited in Claim 8, wherein said seal member is an elongated linear rod having rounded surface portions engaged with the planar surfaces of the edges.

13. The arrangement as recited in Claim 12, wherein said seal rod has a circular cross-sectional configuration for making substantially line sealing contact with the planar surfaces of the edges.

14. The arrangement as recited in Claim 8, wherein said spring clip has a channel-like cross-sectional configuration.

15. In a gas turbine engine including a plurality of circumferentially-arranged and adjacently-spaced segments which define gaps therebetween through which a pressurized gas can flow from a high pressure side to a low pressure side of said segments, a sealing arrangement comprising:
(a) a pair of oppositely inclined edge flanges on said segments having respective oppositely inclined planar surfaces defined thereon;
(b) a seal member disposed between and seated on said inclined planar surfaces of said edge flanges so as to span and close the gap between said edge flanges;
and (c) a yieldable resilient spring clip anchored under said edge flanges and overlying said seal member so as to bias said seal member into sealing contact with said planar surfaces of edge flanges and a sealing relationship with said gap.

16. The arrangement as recited in Claim 15, wherein said spring clip has a pair of opposite longitudinal edge portions and a middle portion interconnecting said opposite edge portions.

17. The arrangement as recited in Claim 16, wherein said opposite edge portions of said spring clip have hook-like configurations, one being the reverse of the other, for extending around and under the edges of the segmented components.

18. The arrangement as recited in Claim 16, wherein said middle portion of said clip is engaged with said seal member and configured in its shape to conform to the shape of a side of said seal member engaged by said clip middle portion.

19. The arrangement as recited in Claim 15, wherein said seal member is an elongated linear rod having rounded surface portions engaged with the planar surfaces of the edges.

20. The arrangement as recited in Claim 19, wherein said seal rod has a circular cross-sectional configuration for making substantially line sealing contact with the planar surfaces of the edges.

21. The arrangement as recited in Claim 15, wherein said spring clip has a channel like cross-sectional configuration.

22. The invention as defined in any of the preceding claims including any further features of novelty disclosed.