CA2013926A1

CA2013926A1 - Leaf seals

Info

Publication number: CA2013926A1
Application number: CA002013926A
Authority: CA
Inventors: Vincent M. Drerup; John R. Hess; Larry W. Plemmons
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1989-07-10
Filing date: 1990-04-05
Publication date: 1991-01-10
Also published as: IT9019629A0; GB9005264D0; JPH0351578A; DE4006498A1; GB2233720B; GB2233720A; IT1239371B; FR2649463B1; DE4006498C2; FR2649463A1; JPH0749832B2; IT9019629A1; IL93669A0; IL93669A

Abstract

Leaf Seals Abstract of the Disclosure An apparatus for effecting a seal between two structural components of a turbo machine or similar device comprises a leaf seal located in the space between the two components and a spring which continuously biases the leaf seal into a sealing position against the components regardless of the pressure differential across the leaf seal.

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Description

13DV-973~ 3 1.~ 2 6 The government has rights in this invention pursuant to Contract No. F33657-84-C-20~1 awarded by the Department of Air Force.
F$eld of the Invention This in~entlon relates to leaf seals for sealing the space be~ween two membars of a turbo ~achine, and, mor~ particularly, to a l-af saa}
includi~g a spring wh~ch biase~ the 1~ seal in a -. ~loced or~sealing po ition:relati~e to the;t~o m~mbers at all tim~s r0gardle~s of the pre~sur~ di~exential across the:leaf seal.
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~ Lea~ seals are com~only e~ployed ~e af~ect a substantially ~luid-tight ~al betwe~n abutting struc~ural~ components in a ~turbo ~machine~ or othe~
: ; ~ apparatus whersln~a ~high~pr~ssure area~is: prssent on~
one side~ of~:~th~ struckural coDponents an~ a lcw pressure~area ls~presen~ on ~he:~opposite slde thereo~
L~af seals:~are typically relatlvely thln, complia~t ; 20 sections whlch are~Pormed~wlth a~bor~ a~apted ~o elid~

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along a pin fixed to o~e of the abutking structural componentsO Where the structural components to be sealed are annular in shape, as in many compcnents of turbo machines, se~mented leaf seals are employed, i.e., r~latively short, arcuate-shaped leaf seals which abut one another to form an essPntially con-tinuous annular seal between the structural compo-nents.
Regard}ess of the particular shape of the structural components to be ealed, lea~ seals ar~
movable to a closed, sealinq position in which they engage each structural component and s-al the space therebetween, and an open position in which at least one portion of the leaf seals diæengage a ~tructur~l 15 component and allow the passage o~ gases in between such components. In most applicatior:ls, moYement of th~ leaf seals along the pin to a closed position is efP~cted by~ applying a pressure dif~erential across the s~al, i~ e., relati~rely high pr-ssur~ on one side o~ the seal and comparatively low pressure on th2 opposite side thereof forces the ~seal~to a clo~ed, sealed~ po~itlon against sur~aces~o~; the ~ abutting structural co~ponen~s to prevent the passage of ga~es thQrebatween.. ~
While leaf seals have ~ound widespread use in turbo machines, their effectlveness in creat~ny a fluid-tight seal is wholly depeDdent on the~ presence 9 ~ ~

of a suf~ici~nt pressure diffsrential betwesn one sid2o~ the seal and the other. During certain operating stages of a turbo machine, the difference in fluid pressure on opposite sides of the }ea~ seals is r~latively low. Under khese conditions, it is pos-sible for the leaf seals to unseat from their engage-ment with the abutting structural components o~ the t~rbo machin~ and allow leakage therebetween~
A relatively small pressure diferential across the leaf seals also permits movemen~ or vibra--tion of the leaf seals with respect to the structural co~ponents of ~he turbo machine which they contact.
This vibration of the leaf seals, which is caused by operakion of th~ turbo machine and o~h~r sources, creates undesirable wear both of th~ lea~ se~ls and the sur~ace~s of the s~ructural components against which the leaf seals seat. Such wear not only re~ults in leakags of gases between the leaf seals and struc tural co~nponents o~ the turbo machine, but can cause 20 premature ïailure thereo~.
Summa:~y of the Invcntion It is therefore among the cbje~ive~ of this imrention to provide: a l~a* ~saal ~or abu~ting or ad~oining s~ruc~ural co~ponents of an app~ratus such a8 a turbo machine to prF~vent the leakage o~ gase~
be~ween such components, which ~reates a reliable, ~luid-tight seal in the space betwe~n such structural l3DV-973~ 3 3 2 ~

components, which resists leakage o~ yases regard7ess of the pressure dif~erential applied to the leaf s~al and whirh resists vibxation or other movement o~ the leaf seal relative tc the structural components to be sealed.
~ hese o~jective are accomplished in an apparatus for sealing the space betwee~ two abutting or adjoining structural c~mponents, such a the components of a turbo mach m e, which comprises a leaf seal and a spring which continuously biases the leaf s~al to a closed, sealed position relative to the structural components to be sealed.
This inYention is prodicated upon the concep~ o~ retaining a lea~ seal in a closed, sealed position with re~pect to adjoining or abutting struc-tural comp~onents by the continuous application of a Iorcs against the leaf seal by a spring o~ other biacing means. Regardles f the pressure dif~erPn-tlal across the leaf seal, the spring or other bia~in~
means maintain~ the lea~ seal in a ~lo~ed, se~l~d position with respect to th~ ad~oi~ing or abutting ~tructural: omponents to bQ sealed.~: ~dditionally, : foxcing th- :lea~ eal~continuously against the~abu~-: ting structural components, v~bration or other rela-ti~e movement betwaen the leaf seal:and æuch struc-tural components is~ reduced, ~thus l~ssening wear b~ween such~:parts~ ::

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13DV-g73~ ~J ~ .13 ~ ~ 6 In one presently preferred embodiment, one o~ ~he s~ructural componen~s mounts one or more pins, each of which is adapted ~o support a leaf seal. A
bore or other opening is formed in th2 leaf seal to fit over such mounting pins. ~he leaf seals are axially movable along such mounting pins between a closed, sealed position wherein one portion of the leaf seal engages a first structural co~ponent and another portion of the lea~ seal engages a second structural co~ponent to close the space therebetween, and an open position in which at least one of the portlons of the leaf seal disengages a structural component to permit the passage Or gases in the space therebetween. A biasing means, preferahly in the ~orm o~ a~ spring, is mounted to one o~ the structural : ~ . components and engages the leaf seal at a point intermediate the portions of th~ lea~ seal which contact the structural co~ponents. The ~pring is e~fective to force the lea~ seal against each struc-tural component 50 as ~o maintai~ ~h~ lea~ seal in a closed, sealed posi~ion at all times. I~ the pr~ssure di~erential aoross thQ leaf seal de rease3 during operation o~ the turbo machine,~the spring neverthe~
le58 retains the~ lea~ s~al ~in~ a seal~d~position r~lative to:th~ structural components to ~prevent any leakage of gases ~therebetween.~; M dit~ionallyl vibra-t~on or oth~r relative movem2nt be~ween ~he:leaf seal ~ 2~.3 and structural components is reduced by the spring force exerted against the leaf seal~
A variety of springs may be utilized to force the leaf seal into engagement with the strUc-~ural components to be sealed. In one embodiment, the spring is U-shaped having oppo~ed legs which are blased away from one another. one leg of the U-shaped -~pring is mounted to the pin which carrie~ the leaf seal, and the other leg engages the 12a~ ~seal at a }O point intermediate its ends so as to bi~as or ~orce the leaf seal into a closed, sealed position against the structural components.
In an alternative embodiment, the biasing means for the lea~ seal is a spiral coil spring having an open center which is ~itted ovex the pin which mounts each leaf seal. One end of th~ coil spring engages a structural component and the oppo~ite end thereoP engages the leaf seal at a poin~ intermediate : it~ ends. The coil spri~g is initia1ly compressed in positioning it between the lea~ seal and structural component, and then elongates to forca the leaf seal to a closed, sealed position:relati~e to the struc-~ral co~ponents~
In a still fur~her embodiment, the biasing : 25 m~ans: is a sinusoidal-shaped spring h~ing opposed ends and an arcuate section therebetween. The ends of the sinusoidal-shaped spring are ~ixedly mounted to : `
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~ ~'3 one of the s~ructural ~o~ponents so that the axcuate ~ction therebetween engage~ the leaf sea1 and fsrces it i~to a closed, sealed position with re~pect to the ~tructural co~ponents to be sea1ed.
DescriE~ion o~ the Drawinqs Th~ structure, operation and adYantages of the pre~ently pr~ferred embodiment o~ this in~ention will become ~urther apparent upon consideration o~ the following description, tak~ in conjunction.with the acco~panying:drawings, wherein.
: Fig. 1 is a schemati~ partial cross sec-tiona1 view of a portion of a ~urbo machine illu~trat-ing on~ 1Ocation in which tha lea~ seal and spring o~
. ~is invention can be utilized;
~lg. 2 is. an en1arged c~oss sectional view o~ a;portion of Fig. 1 iI1ustratins one~embodiment o~
the lea~ s~al and spring horein;
: Fig. 3 is a view si~ilar to Fig. 2 sh~wing an alternative e~bodimen~ of the spring ~ployed with the loaf sea1;herein;
Fig. 4 ~ls a view similar to Flgs. 2 and 3 showin~ a:still further embodiment o~ the spring and loaf saal co~ inatlon of this~invention; and ~
~ Ylg~. 5 is :a:~cross sec~ional vie~ taken : 25 generally~along lino 5-5 of;Fig. 4.

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13DV~9734 Detailed Description of ~he Inv~ntion Referring now to Fig. 1, a fragmentary seictional view of a turbo machine 10 is shown ~or the purpose of illustrating one environment in which the segmented leaf seal 12 and spring 14 o~ this invention can be ~ployed. The detailed construction of the turbo machine 10 fo~ms no part of.this invention per se and is thus not discussed in d-tail herein.
Refexence should be made to UOS. Paten~ No. 4,1~6~405, as6igned to -the same assignee as this invention, for a d~tail~d discussion of the turbo machine 10, the disclosure of which is incorporated by reference in its entir-ty herein.
For purposes o~ the present di~cussion, the l1 turbo machin~ 10 includes a combustor 15 and a high pressur- turbine 16. The high pressuxe turbin~ 16 i~cludes ~any number o~ stage~, each stage consist~ng of a row o~ turbine nozzl~s 17 and a~ row:of turbin~ :.
blades 18 altarnately diqposed as is w-ll known in the : 20 art.
Th~ support st ~ cture for the hiqh pressurei !
tu~bine includes, ~on thQ :radially out-r side,~ a ,, : . combustor casing 19, an :outeir turbi~ne ring 21 and~a : turbin- casing 22 whi d are secured together by ~a l;
pluralityl of circumferentially sp w ed bolts 23. on~
: the radially~inner~side of ~he turbine,~ thiere is an inner ~Go~UStor casinq 24 s-oured to an i~ner turbina , :

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13D~-9734 _g_ ring 26 by a plurality of bolt~ 27. On the rear side of the turbine ring 26, a ~lange 32 extends radially outwardly to act a~ an axial load stop for the rear inner rail 33 which projects radially inwardly from the inner band 34 to fric~ionally engage the flange 32. A bracket 36 is also connected to the inner turbine ring 26 which, in turn, supports a statio~ary outer seal 37. The associated rotating inner seal~
member 38 is supported by a bracket 39 extending forward from the turbine disk 40~
On the radially outer side of the turbine nozzle 17, the outer turbine ring 21 provides support by way of an axially extending stop 41 and a U-flange 42-o The U-flange 42 provides support in ~th~ axial : 15 direation by engaging the rear face o~;th~ rear outer rail 43 extending radially outwardly ~rom the outer band 44. An axially extending stop 4~ frictionally engages an outer lug 48 exte~ding radially outwardly ~rom th~ van~ 14 to provide support in tha circum~er-ential direction.
Cooling of the system componen~s de~cribed above~ crea~e~ areas of higher pressura ~and lower ; pressure in the combustor 15 and~tur~ine 16 which mus~
: be: sealed~rom one another. Conventionally, rela~
tively high~ pressure cooling~air ~is circulated around;~:
the annular:combustor 15 between tha combus~or oute~ :
casing 19 and ~the combu~tor ou~-r liner 49.: see ~'J t.3 ~ 7J ~

~10 -arrows in Fig. 1. Similarly, the cooling air is circulated between the inner combustor casing 24 and the inner combustion liner 51. A portion of the cooling air passes through holes 52 in the combustor liner to cool the inner walls thereo~, creating an area of relatively low pressure, while mcst of ~he air flows downstream to cool the tu~bine nozzl~s and shrouds. It is necessary to prevent leakage of air between the combustor and vane stage interface in order to obtain the desired flow of cooling air to the syætem components~
Referring to Figs. 1 and 2, one embodiment of the sealing device of this invention is positioned ~ . in the space 60 between the vane forward outer rail 61 15 and the combustor rear flange 62, i.e., the structural components of the turbo machine ~0 lo~ate~ at th~
combustor-vane stage in~erface. A l~a~ seal 64 i~
located in such spac~ 60 and has an inner end 66 ~upported within a notch ~7 ~ormed in the vane forward outer rail 61, and an outer end 68 engageabIe with the ~ombustor rear flange 62. This lea~ seal 64 is ~lidably mounted on a pin 70 connected to the vane forward outer~rail 61 by a nut~ 72. The lea~ seal 64 is mova~le b~tween a clo~ed, sealed position whereln its inner end 66 and outer end 68 engage the outer rall ~1 and rear flange 62, respec~ively, as shown in Figs~ 1 and 2, and an open position in which at least :

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13DV~9734 ona of ~he ends 66, 68 of the leaf seal 64 disengage a structuxal component.
In the embodiment of Figs. 1 and 2, a U-shaped spring 74 has a firs~ arm 76 fixedly mounted on the pin 70 by nut 72 rearwardly of the outer rail 61, and a ~econd arm 78 carried on the pin 7Q on the forw rd ~ide of ou~er rail 61 in angagement with the lea~ seal 64. The arms 76, 78 are blasad away ~rom one another so that in .the position sho~n in Fig. 2, the second arm 78 of spring 74 urges the leaf spring 64 into engagement with the outer rail 61 and rear flange~6Z to seal the space 60 therebetween. Prefer-ablyl the second arm 78 contacts the leaf seal 64 at a point intermediate its inner ~nd 66 and outer end 68 : 15 so tha~ such ends 66, 68 are positively s~aled against ~he outer rall:61 and rear flange 62.
Referring now to Fig~ 3, the:spring 74 o~
Figs. 1 and 2 is eliminated and replaced:with a spiral coil,spring 80 for maintaining ~he leaf seal 64 in po~ition against the outer rail 61 and rear ~lange 62~
The coil spring 80 has an:open center adapted ~o slide along the~pin 70, a first end 84 which engag@s; ~he forwar~ face of the outer raiI 61 and a second end 8~
which en~ages~he lea~ seal 64~at a point inte~mediatQ
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its inner and outer ends. 66~ 68, resp~ctiYely. The coil spring 80~ is inièially comprass~d in~ the cours~
0~ pl~CiAg ~ it between:the outer rall 61 and le ~ seal 64, and then it extends so tha~ the second end 86urge~ the leaf seal 64 forwardly and into seallng engagement with the outer rail 61 and rear ~lange 62.
A still further embodiment of this in~ention is illustrated in Figs. 4 and 5 in which a generally s~nusoidal-shaped spring 88 is used in place of the coil spring ZO or U-shaped spring 7~. The sinu-æoidal-shaped spring 88 ha opposed ends 90 and 92 with a center section 94 formed in a~ arcuate, genero IO ally sinusoidal shape. The ~spring 88 is fixedly attached at each end 90, 92 by plns 70 and nu~s 72 so that khe arouate, center section 94 engages the leaf sQal 64 at a point intermediate its ends 66, 6~. T~e center section 94 of spring ~8 is compressed a~ it is ~: 15 positioned betwQen the outer rail 61 and leaf se~l 64 :
so that it urges both ends 66, 68 of the leaf seal 64 into a sealing position against the outer rail 61 and rear flange S2.
While the invention has been described with zo re~erence to a preferred e~bodimen~ will be under~tood by tho~ ~killed in ~he art ~ha~ various changes may be mad~ and eguivalen~s ~ay ~e substituted :
for elements thareof wl.thout departing from the~scope o~ the invention. In addition, many modifications may be made to~ad~pt ~ particular situation or material to tha teachings of the inven~ion withou~ d~part~ng fro~

~he essential scope thereof.

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For example, the combined l~a~ æeal and ~pring arrangements illu~trated ~n the dra~ings were shown in the environmen~ of a turbine nozzle and a turbine machine to create a seal between two struc-tural elements, i.e., the combustor rear flange andthe vane ~orward outer rail. It should be understood, however, that the leaf seal and springs disclosed h~rein could~ be utilized in essentially any applica-tion in which leaf seals are currently employed.
Additionally, it is contemplated that ~a variety of diff~rent springs or other biasing means could be utilized to malntain the leaf seal in a sealed po~i-.
tion withou~ departing ~rom the scop~ sf this inven-~, . . .
t~on.
~~I5 ~ There~ore, it 1~ intended that the in~entlon : not be~limited to th~ part1cular e~bodiment disclosed as the best mode contemplated for carrylng out this inventio~, but that the inven~ion will include all embodiments falling within the scope o~ th~ appended : 20 ~laim3. ~ :

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Claims

1. Apparatus for effecting a seal of a space between a first member and a second member, comprising:
a leaf seal located in the space between the first member and the second member, said leaf seal being movable to a sealing position in which said leaf seal engages said first member and said second member to seal the space therebetween;
biasing means connected between one of said first and second members and said leaf seal for continuously forcing said leaf seal to said sealing position.

2. The apparatus of claim 1 in which said biasing means is a substantially U-shaped spring having a first arm and a second arm which are biased away from each other, said first arm being fixedly mounted to one of said first and second members and aid second arm engaging said leaf seal to force said leaf seal to said sealing position against said first and second members.

3. The apparatus of claim 1 in which said biasing means is a coil spring having a first end and a second end, said coil spring being mounted between one of said first and said second members and said leaf seal to force said leaf seal into said sealing position.

4. The apparatus of claim 1 in which said biasing means is a sinusoidal-shaped spring having opposed ends and an arcuate-shaped portion between said ends said sinusoidal-shaped spring being mounted to one of said first and second members so that said arcuate-shaped portion engages and forces said leaf seal into said sealing position.

5. Apparatus for effecting a seal of a space between a first member and a second member, comprising:
a leaf seal, support means for mounting said leaf seal with respect to the space between the first and second members so that said leaf seal is movable to a sealing position against said first and second members to substantially prevent the passage of gases through the space therebetween;
biasing means carried by s id support means for continuously forcing said leaf seal into said sealing position.

6. The apparatus of claim 5 in which said support means is a pin mounted to said first member.

said leaf seal being mounted on said pin and axially slidable therealong to said sealing position relative to said first and second members.

7. The apparatus of claim 6 in which said biasing means comprises a U-shaped spring having first and second arms which are biased away from each other, said first arm being fixedly mounted to said pin and said second arm being carried on said pin in a position to engage said leaf seal, said first and second arms being initially deflected toward each other and then released so that said second arm forces said leaf seal into said sealing position against said first and second members.

8. The apparatus of claim 6 in which said biasing means comprises a coil spring having all open center and opposed ends, said open center of said coil spring receiving said pin so that one end of said coil spring contacts said first member and said other end of said coil spring engages said leaf seal, said coil spring being initially compressed between said first member and said leaf seal and then released to force said leaf seal into said sealing position.

9. The apparatus of claim 6 in which said biasing means comprise a sinusoidal-shaped spring having opposed ends and an arcuate-shaped portion between said ends, said opposed ends of said sinusoidal spring being fixedly mounted to said first member so that said arcuate-shaped portion engages said leaf seal and forces said leaf seal to said sealing position.

10. Apparatus for effecting a Deal of a space between a first member and a second member comprising:
a leaf seal having a first portion engageable with said first member and a second portion engageable with said second member, said first and second portions of said leaf seal being spaced from one another.
support means for mounting said leaf seal with respect to the space between said first and second members so that said leaf spring is movable to a sealed position wherein said first portion thereof engages said first member and said second portion thereof engages said second member to substantially prevent the passage of fluid through the space between said first and second members;

biasing means carried by said support means for applying a force to said leaf seal at a point between said first and second portions thereof to force said leaf seal into said sealing position.

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