Abstract:
A method for assembling a gas turbine engine is provided. The method comprises coupling a first turbine nozzle within the engine, coupling a second turbine nozzle circumferentially adjacent the first turbine nozzle such that a gap is defined between the first and second turbine nozzles and providing at least one spline seal including a substantially planar body. The method also comprises forming at least one catch to extend outward from the body portion of the at least one spline seal, and inserting the at least one spline seal into a slot defined in at least one of the first and second turbine nozzles to facilitate reducing leakage through said gap, such that a portion of the at least one spline seal is received within a recess defined within the turbine nozzle slot to facilitate retaining the at least one spline seal within the turbine nozzle slot.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to turbine engines and more particularly, to methods and apparatus for assembling gas turbine engines. 
   Known gas turbine engines include combustors which ignite fuel-air mixtures which are then channeled through a turbine nozzle assembly towards a turbine. At least some known turbine nozzle assemblies include a plurality of arcuate nozzle segments arranged circumferentially. At least some known turbine nozzles include a plurality of circumferentially-spaced hollow airfoil vanes coupled by integrally-formed inner and outer band platforms. More specifically, the inner band forms a portion of the radially inner flowpath boundary and the outer band forms a portion of the radially outer flowpath boundary. 
   Within known turbine nozzle assemblies, the turbine nozzle segments are coupled circumferentially within the turbine engine. More specifically, because of temperature differentials that may develop and to accommodate thermal expansion, known turbine nozzles are positioned such that a gap or clearance is defined between pairs of circumferentially-adjacent nozzles. To facilitate preventing cooling air supplied to such nozzle segments from leaking through the clearance gaps, at least some known turbine nozzle assemblies include a plurality of spline seals. 
   Known spline seals are substantially flat pieces of material that are inserted within slots defined in the turbine nozzles. More specifically, at least some known nozzle assemblies include a loading slot that facilitates the installation of the spline seals within the spline seal slots. However, depending on the operation of the turbine engine, at least some known spline seals may undesirably slip out of the spline seal slots through the loading slot. Such seals may be channeled downstream and cause damage to other engine components. Moreover, over time, continued operation with decreased cooling of the turbine nozzles adjacent such spline seal slots may limit a useful life of the turbine nozzle. 
   BRIEF SUMMARY OF THE INVENTION 
   In one aspect, a method for assembling a gas turbine engine is provided. The method comprises coupling a first turbine nozzle within the engine, coupling a second turbine nozzle circumferentially adjacent the first turbine nozzle such that a gap is defined between the first and second turbine nozzles and providing at least one spline seal including a substantially planar body. The method also comprises forming at least one catch to extend outward from the spline seal body, and inserting the at least one spline seal into a slot defined in at least one of the first and second turbine nozzles to facilitate reducing leakage through said gap, such that a portion of the at least one spline seal is received within a recess defined within the turbine nozzle slot to facilitate retaining the at least one spline seal within the turbine nozzle slot. 
   In another aspect, a seal assembly for use with a turbine engine turbine nozzle assembly is provided. The seal assembly includes at least one spline seal sized for insertion within a slot formed within a turbine nozzle. The at least one spline seal is configured to facilitate reducing leakage through the turbine engine turbine nozzle assembly, and includes a substantially planar body and at least one catch extending outward from said body. A portion of the at least one spline seal is sized for insertion within a recess defined within the turbine nozzle slot. 
   In a further aspect, a turbine nozzle assembly for a gas turbine engine is provided. The nozzle assembly includes a plurality of turbine nozzles and a seal assembly. Each turbine nozzle includes an outer band, an inner band, and at least one airfoil vane extending between the outer and inner bands. A portion of each of the plurality of turbine nozzles defines a slot therein. The slot includes at least one recessed portion defined therein. The seal assembly includes at least one spline seal sized for insertion within the turbine nozzle slot to facilitate reducing leakage between circumferentially adjacent pairs of the turbine nozzles. The at least one spline seal includes a substantially planar body and at least one catch extending outward from the body. A portion of the at least one spline seal is sized for insertion within the at least one slot recess. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of an exemplary gas turbine engine; 
       FIG. 2  is a side view of an exemplary turbine nozzle that may be used with the gas turbine engine shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of an exemplary spline seal that may be used with the turbine nozzle shown in  FIG. 2 ; 
       FIG. 4  is a perspective view of an alternative embodiment of the spline seal shown in  FIG. 3 ; 
       FIG. 5  is perspective view of an exemplary spline seal assembly formed using the spline seals shown in  FIGS. 3 and 4 ; 
       FIG. 6  is a partial cut-away plan view of the spline seal assembly shown in  FIG. 5  during installation in an exemplary turbine nozzle assembly; 
       FIG. 7  is a perspective view of another alternative embodiment of the spline seal shown in  FIG. 3 ; and 
       FIG. 8  is a side view of the spline seal shown in  FIG. 7  and installed in an alternative embodiment of the turbine nozzle shown in  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a schematic illustration of an exemplary gas turbine engine  10  including a low pressure compressor  12 , a high pressure compressor  14 , and a combustor  16 . Engine  10  also includes a high pressure turbine  18  and a low pressure turbine  20 . Compressor  12  and turbine  20  are coupled by a first shaft  21 , and compressor  14  and turbine  18  are coupled by a second shaft  22 . In one embodiment, gas turbine engine  10  is an LM2500 engine commercially available from General Electric Aircraft Engines, Cincinnati, Ohio. In another embodiment, gas turbine engine  10  is a CFM engine commercially available from General Electric Aircraft Engines, Cincinnati, Ohio. 
   In operation, air flows through low pressure compressor  12  supplying compressed air from low pressure compressor  12  to high pressure compressor  14 . The highly compressed air is delivered to combustor  16 . Airflow from combustor  16  is channeled through a turbine nozzle (not shown in  FIG. 1 ) to drive turbines  18  and  20 , prior to exiting gas turbine engine  10  through an exhaust nozzle  24 . 
     FIG. 2  is a side view of an exemplary turbine nozzle  50  that may be used with a gas turbine engine, such as turbine engine  10  (shown in  FIG. 1 ). In the exemplary embodiment, nozzle  50  is one segment of a plurality of segments that are positioned circumferentially to form a nozzle assembly (not shown in  FIG. 2 ) within the gas turbine engine. Nozzle  50  includes at least one airfoil vane  52  extending between an arcuate radially outer band or platform  54 , and an arcuate radially inner band or platform (not shown). More specifically, in the exemplary embodiment, outer band  54  and the inner band are each integrally-formed with airfoil vane  52 . 
   In the exemplary embodiment, nozzle  50  also includes an axial spline seal slot  60  and a radial spline seal slot  62  that are each formed in a generally axially-extending face  64  of nozzle  50 . More specifically, slot  60  extends generally axially through a portion of face  64  and slot  62  extends generally radially through a radial flange  66  portion of nozzle  50 . In the exemplary embodiment, slot  60  is also formed integrally with a loading slot portion  68  that facilitates the installation of axial spline seals (not shown) into the segmented nozzle assembly. 
   A thickness T of spline seal slot  60  is substantially constant through slot  60 . In the exemplary embodiment, loading slot portion  68  is frusto-conical such that a thickness T LS  of slot portion  68  increases from slot  60  to a stop projection  72  adjacent a trailing end  76  of slot portion  68 . Stop projection  72  facilitates maintaining the spline seal within slot  60 . In each embodiment, spline seal slot  60  is formed with a recessed area (not shown in  FIG. 2 ) that is sized to receive a portion of a spline seal (not shown in  FIG. 2 ) therein to facilitate maintaining the spline seal within slot  60 , as described in more detail below. 
   During assembly of the nozzle assembly, a plurality of nozzles  50  are positioned circumferentially adjacent to each other to form the nozzle assembly. Specifically, nozzles  50  are positioned relative to each other such that a clearance gap is defined between each pair of circumferentially adjacent pairs of nozzles. More specifically, the clearance gap is defined between circumferentially adjacent and opposing nozzle end faces  64 . To facilitate sealing the clearance gaps, spline seals (not shown in  FIG. 2 ) are inserted within a pair of circumferentially adjacent spline seal slots  60 . More specifically, when positioned within slots  60 , each spline seal circumferentially bridges the clearance gap to facilitate preventing leakage through the gap. 
     FIG. 3  is a perspective view of an exemplary spline seal  100  that may be used in turbine nozzle  50  (shown in  FIG. 2 ). In the exemplary embodiment, spline seal  100  is substantially rectangular and is bordered by an outer perimeter  102  including a pair of circumferentially-spaced sides  104  that are connected by a leading edge side  106  and a trailing edge side  108 . Alternatively, spline seal  100  may have any non-rectangular shape that enables seal  100  to function as described herein. Moreover, in other embodiments, spline seal  100  may be oriented such that leading edge side  106  and trailing edge side  108  are inverted. 
   Spline seal  100  includes a body portion  120  and at least one catch  122 . Specifically, in the exemplary embodiment, seal  100  is formed substantially symmetric about a centerline axis of symmetry  124 , and thus includes a pair of opposed, identical catches  122 . Body portion  120  is substantially planar and includes a radially outer surface  125  and an opposite radially inner surface  126 . Body portion  120  is sized for insertion within spline seal slot  60  and has a thickness T B  that is thinner than spline seal slot thickness T. In one embodiment, spline seal  100  is fabricated from a substantially flat piece of sheet metal. 
   Each catch  122  extends outward from body portion  120 . Specifically, in the exemplary embodiment, each catch  122  extends obliquely outward from seal outer perimeter  102 , and more specifically, from each seal side  104  adjacent leading edge side  106 . More specifically, in the exemplary embodiment, a downstream side  127  of each catch  122  extends a longer distance d 1  outward from side  104  than an upstream side  128  of each catch  122 . Accordingly, in the exemplary embodiment, each catch  122  is substantially triangular-shaped. Alternatively, at least one catch  122  may extend from any portion of body portion  120 , or have any shape, that enables catch  122  to function as described herein. Moreover, although two catches  122  are illustrated, spline seal  100  may include more or less than two catches  122 . 
   In the exemplary embodiment, because each catch  122  is triangular-shaped, an outer edge  130  of each catch  122  is oriented at an oblique angle θ with respect to body outer edge  104 . Alternatively, catch  122  may be oriented at any angle θ with respect to outer edge  104  that enables catch  122  to function as described herein. In the exemplary embodiment, each catch  122  is formed integrally with body portion  120 . Alternatively, at least one catch  122  may be coupled to body portion  120 . 
   In the exemplary embodiment, spline seal  100  also includes a division slot or cut  140  that extends a distance axially downstream from spline seal leading edge side  106 . In the exemplary embodiment, slot  140  is substantially centered between spline seal sides  104  and between catches  122 . Alternatively, slot  140  is non-centered with respect to spline seal  100 . Specifically, in the exemplary embodiment, slot  140  extends from spline seal leading edge  106  to a relief stop hole  142  extending through spline seal  100 . Stop hole  142  facilitates reducing stresses that may be induced to spline seal  100  adjacent catches  122  and also facilitates preventing the initiation or propagation of cracks that may develop within spline seal  100  between catches  122 . Slot  140  enables spline seal  100  to be inserted into spline seal slot  60  (shown in  FIG. 2 ) as described in more detail below. 
   During assembly, spline seal  100  is inserted through loading slot portion  68  and into spline seal slot  60  such that spline seal  100  circumferentially bridges a clearance gap (not shown in  FIG. 3 ) defined between adjacent nozzles  50  (shown in  FIG. 2 ). More specifically, spline seal  100  is inserted into slot  60  such that seal leading edge side  106  is upstream from seal trailing edge side  108 . Because an outer width W of spline seal  100  is wider than a width (not shown in  FIG. 3 ) of slot  60 , as defined between adjacent nozzles  50 , seal slot  140  enables catches  122  to flex inward towards seal centerline  124  such that the outer width W of spline seal  100  is reduced and as such, spline seal  100  may be slidably positioned within slot  60 . More specifically, in the exemplary embodiment, when spline seal  100  is fully inserted into slot  60 , each catch  122  is biased to extend outward from spline seal body portion  120  and is received within a recessed area defined within slot  60 . The recessed areas retain each catch  122 , which limits the axial movement of spline seal  100  within slot  60 . As such, because the axial movement of spline seal  100  is limited, catches  122  facilitate maintaining each seal  100  within spline seal slot  60 , and thus facilitate preventing spline seal  100  from undesirably slipping or backing out from slot  60 . As a result, each catch  122  facilitates minimizing leakage through the segmented turbine nozzle assembly clearance gaps and thus facilitates enhancing engine performance and component life expectancy. 
     FIG. 4  is a perspective view of an alternative embodiment of spline seal  100 . The embodiment illustrated in  FIG. 4  is substantially similar to the embodiment illustrated in  FIG. 3  and components of spline seal  100  illustrated in  FIG. 4  that are identical to components of spline seal  100  illustrated in  FIG. 3 , are identified in  FIG. 4  using the same reference numerals used in  FIG. 3 . Accordingly, spline seal  100  includes at least one catch  150  that extends outward from body portion  120  and, more specifically, outward from seal outer perimeter  102 . 
   In the exemplary embodiment, each catch  150  extends obliquely outward from seal outer perimeter  102 , and more specifically, from each seal side  104  adjacent trailing edge side  108 . More specifically, in the exemplary embodiment, a downstream side  152  of each catch  150  extends a greater distance outward from each side  104  than catch upstream side  154  extends from side  104 . Accordingly, in the exemplary embodiment, each catch  150  is substantially triangular-shaped. Alternatively, at least one catch  150  may extend from any portion of body portion  120 , or have any shape, that enables catch  150  to function as described herein. Moreover, although two catches  150  are illustrated, spline seal  100  may include more or less than two catches  150 . 
   In the exemplary embodiment, because each catch  150  is triangular-shaped, an outer edge  160  of each catch  150  is oriented at an oblique angle β with respect to body outer edge  104 . Alternatively, catch  150  may be oriented at any angle β with respect to outer edge  104  that enables catch  150  to function as described herein. In the exemplary embodiment, each catch  150  is formed integrally with body portion  120 . Alternatively, at least one catch  150  may be coupled to body portion  120 . 
   In the exemplary embodiment, spline seal  100  also includes a division slot or cut  162  that extends a distance axially upstream from spline seal trailing edge side  108 . In the exemplary embodiment, slot  162  is substantially centered between spline seal sides  104  and between catches  150 . Alternatively, slot  162  is non-centered with respect to spline seal  100 . Specifically, in the exemplary embodiment, slot  162  extends from spline seal trailing edge  108  to a relief stop hole  164  extending through spline seal  100 . Stop hole  164  facilitates reducing stresses that may be induced to spline seal  100  adjacent catches  150  and also facilitates preventing the initiation or propagation of cracks that may develop within spline seal  100  between catches  150 . Similar to slot  140 , slot  162  enables spline seal  100 , and specifically catches  150 , to flex to such that seal  100  may be inserted into spline seal slot  60  (shown in  FIG. 2 ). 
   During assembly, when spline seal  100  is fully inserted within spline seal slot  60 , each catch  150  extends outward from spline seal body portion  120  and is received within a recessed area (not shown in  FIG. 4 ) defined within slot  60 . The recessed areas retain each catch  150 , which limits the axial movement of spline seal  100  within slot  60 . As such, because the axial movement of spline seal  100  is limited, catches  150  facilitate maintaining each seal  100  within spline seal slot  60 , and thus facilitate preventing spline seal  100  from undesirably slipping or backing out from slot  60 . As a result, each catch  150  facilitates minimizing leakage through the segmented turbine nozzle assembly clearance gaps and thus facilitates enhancing engine performance and component life expectancy. 
     FIG. 5  is perspective view of an exemplary spline seal assembly  200  formed using the spline seal embodiments shown in  FIGS. 3 and 4 .  FIG. 6  is a partial cut-away plan view of a partial installation of spline seal assembly  200  in an exemplary turbine nozzle assembly  202 . In the exemplary embodiment, nozzle assembly  202  includes a pair of circumferentially-adjacent turbine nozzles  50  that are spaced a circumferential distance d S  apart such that a clearance gap  204  is defined between nozzles  50 . As shown in  FIG. 6 , each nozzle spline seal slot  60  is formed with at least one recessed area  210  depending on the application and the seal assembly  200  being utilized. 
   In the exemplary embodiment, each spline seal slot  60  includes a forward recessed area  212  and an aft recessed area  214 . Each recessed area  210  is sized to receive a catch  122  or  150  therein to facilitate retaining seal assembly  200  within slot  60  during engine operation. Specifically, the size, shape, and number of areas  210  is variably selected based on the seal assembly  200  being utilized. 
   As shown in  FIG. 5 , seal assembly  200  is fabricated from a pair of seals  100  coupled together. Specifically, the embodiment of the seal  100  shown in  FIG. 3  is coupled against the embodiment of the seal  100  shown in FIG.  4 . As such, seal assembly  200  includes two forward catches  122  and two aft catches  150 . In an alternative embodiment, any number of catches  122  and/or  150  may be utilized depending on the application. In one embodiment, seals  100  are coupled together prior to being inserted in slot  60 . Alternatively, and as shown in  FIG. 6 , each seal  100  within seal assembly  200  is inserted independently into slot  60 . 
   During assembly of seal assembly  200  within nozzle assembly  202 , initially a first seal  100  is inserted within slot  60  and is slid through slot  60  until catches  122  are received in forward recessed areas  212 . In the exemplary embodiment, a second seal  100  is then inserted within slot  60  such that the second spline seal  100  is against the first spline seal, and such that the catches  150  extending from the second spline seal  100  are received within recessed areas  214 . As such, when spline seal assembly  200  is fully inserted into slot  60 , because catches  122  and  150  are biased outward from respective spline seal body portions  120 , catches  122  and  150  facilitate limiting an amount of axial movement of spline seals  100 . As such, during engine operation, catches  122  and  150  facilitate maintaining spline seal assembly  200  within spline seal slot  60 , and thus facilitates preventing spline seals  100  from undesirably slipping or backing out from slot  60 . As a result, catches  122  and  150  facilitate minimizing leakage through the segmented turbine nozzle assembly clearance gaps  204  and thus facilitates enhancing engine performance and component life expectancy. 
     FIG. 7  is a perspective view of a further alternative embodiment of a spline seal  100  that may be used within gas turbine engine  10  (shown in  FIG. 1 ).  FIG. 8  is a side view of the embodiment of the seal  100  illustrated in  FIG. 7  and coupled within an alternative embodiment of turbine nozzle  50 . The spline seal embodiment illustrated in  FIG. 7  is substantially similar to the embodiment illustrated in  FIG. 3 , and components of spline seal  100  illustrated in  FIG. 7  that are identical to components of spline seal  100  illustrated in  FIG. 3 , are identified in  FIG. 7  using the same reference numerals used in  FIG. 3 . Moreover, the turbine nozzle embodiment illustrated in  FIG. 8  is substantially similar to the turbine nozzle embodiment illustrated in  FIG. 2 , and components of spline seal  100  illustrated in  FIG. 8  that are identical to components of spline seal  100  illustrated in  FIG. 2 , are identified in  FIG. 8  using the same reference numerals used in  FIG. 2 . Accordingly, turbine nozzle  50  includes at least one airfoil vane  52 , axial spline seal slot  60  and radial spline seal slot  62 . 
   As shown in  FIG. 8 , slot  60  includes at least one recessed area  350  that facilitates receiving a catch  360  extending from a spline seal  100  inserted therein, as described below in more detail. More specifically, in the exemplary embodiment, each recessed area  350  extends radially outward and/or radially inward from slot  60  depending on the slot seal  100  to be inserted within slot  60 . 
   As shown in  FIG. 7 , in the exemplary embodiment, spline seal  100  includes two catches  360  that project outward from body portion  120  and, more specifically, outward from radially outer surface  125 . The number, size, location, and shape of catches  360  are variably selected depending on the application. In the exemplary embodiment, catches  360  are substantially circular. In an alternative embodiment, spline seal  100  may also include at least one catch  360  that either also, or only, projects outward from radially inner surface  126 . 
   During engine operation, when spline seal  100  is fully inserted into slot  60 , because catches  360  extends outward from spline seal radially outer surface  125 , catches  360  are received within recessed areas  350  and facilitate limiting an amount of radial and axial movement of spline seal  100 . As such, during engine operation, catches  360  facilitate maintaining spline seal  100  within spline seal slot  60 , and thus facilitate preventing spline seal  100  from undesirably slipping or backing out from slot  60 . As a result, catches  360  facilitate minimizing leakage through the segmented turbine nozzle assembly clearance gaps and thus facilitates enhancing engine performance and component life expectancy. 
   In an alternative embodiment, catches  360  are received in recessed areas formed on an adjacent spline seal  100 , for example, as is illustrated in  FIG. 6 . In such an embodiment, catches  360  facilitate interlocking the seals  100  within the seal assembly together to facilitate preventing either seal  100  from undesirably slipping or backing out from slot  60 . 
   In each embodiment, the above-described spline seals include at least one catch that facilitates preventing the spline seal from inadvertently backing out of the nozzle assembly spline seal slots. More specifically, in each embodiment, each catch extends outward from the body portion of the spline seal to facilitate limiting movement of the spline seal within the spline seal slot. As a result, during engine operation, the catches facilitate reducing leakage through the clearance gap defined between circumferentially adjacent turbine nozzles. Accordingly, engine performance and component useful life are each facilitated to be enhanced in a cost effective and reliable means. Moreover, the invention provides a means wherein existing spline seal slots can be modified to facilitate enhancing turbine engine performance. 
   Exemplary embodiments of turbine nozzles are described above in detail. The spline seals are not limited to use with the specific nozzle embodiments described herein, but rather, the spline seals can be utilized independently and separately from other turbine nozzle components described herein. Moreover, the invention is not limited to the embodiments of the spline seals described above in detail. Rather, other variations of spline embodiments may be utilized within the spirit and scope of the claims. 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.