Patent Publication Number: US-10767498-B2

Title: Turbine disk with pinned platforms

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to gas turbine engines, and more specifically to composite blades for use in gas turbine engines. 
     BACKGROUND 
     Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Left-over products of the combustion are exhausted out of the turbine and may provide thrust in some applications. 
     The turbine may include turbine wheels having disks and a plurality of blades that extend radially away from the disks. To withstand heat from the combustion products received from the combustor, the blades may be made from ceramic matrix composite materials that are able to interact with the hot combustion gasses. Making a root, platform, and airfoil of each blade may present design challenges. 
     SUMMARY 
     The present disclosure may comprise one or more of the following features and combinations thereof. 
     A blade assembly for use in a gas turbine engine may include a blade, a platform, and a pin. The blade may comprise ceramic matrix composite materials. The blade may include and an airfoil that extends outwardly away from the root in a radial direction relative to an axis. The blade may be formed to include a first passageway that extends through the blade. The platform comprises ceramic matrix composite materials and defines at least a portion of a flow path around the airfoil to guide hot, high-pressure gasses around the airfoil while minimizing thermal transfer of the hot, high-pressure gasses to the root of the blade during use of the blade assembly in a turbine. The platform may be formed to include a second passageway that extends through the platform. The pin is located in the second passageway and the first passageway to couple the platform with the blade. 
     In some embodiments, the platform may include an outer radial surface and an inner radial surface spaced apart radially from the outer radial surface. The platform may be formed to include a blade-receiving passageway that extends through the outer radial surface and the inner radial surface. The portion of the blade may be located in the blade-receiving passageway. 
     In some embodiments, the pin, the first passageway, and the second passageway may extend in an axial direction relative to the central axis. In some embodiments, the pin, the first passageway, and the second passageway may extend in a circumferential direction relative to the central axis. 
     In some embodiments, the platform may include a first side wall and a second side wall that extend radially between the outer radial surface and the inner radial surface. The second passageway may extend into at least one of the first side wall and the second side wall. 
     In some embodiments, the first side wall may be formed to include a cutout that extends into the first side wall in a circumferential direction relative to the central axis toward the second side wall. The second side wall may be formed to include a cutout that extends circumferentially into the second side wall. The cutouts may be sized to receive a side wall of an adjacent platform. 
     In some embodiments, the second passageway may open into the blade-receiving passageway. In some embodiments, the first passageway may be a non-circular elongated slot. 
     In some embodiments, the blade and the platform are independent components. The blade and the platform are independent components may not be substantially co-infiltrated together. 
     According to another aspect of the present disclosure, a blade assembly for a gas turbine engine may include a blade comprising ceramic materials, a platform comprising ceramic materials, and a pin. The platform may be formed to include a blade-receiving passageway that extends through the platform. The platform may be arranged around the blade so that a portion of the blade is located in the blade-receiving passageway. The pin may be located in the platform and the blade to couple the platform with the blade. 
     In some embodiments, the blade includes a leading edge and a trailing edge spaced apart axially from the leading edge relative to an axis. The pin may extend into the platform and the blade in an axial direction relative to the axis. 
     In some embodiments, the pin may have a non-circular cross-section when viewed along the axis. In some embodiments, the blade includes a leading edge and a trailing edge spaced apart axially from the leading edge relative to an axis. The pin may extend into the platform and the blade in a circumferential direction relative to the axis. 
     In some embodiments, the platform includes a first side wall and a second side wall spaced apart from the first side wall. The platform may be formed to include a passageway that extends through the first side wall and the second side wall. The pin may be located in the passageway. 
     In some embodiments, the platform includes a first side wall and a second side wall spaced apart from the first side wall. The first side wall may be formed to include a cutout that extends toward the second side wall. The second side wall may be formed to include a cutout that extends toward the first side wall. 
     In some embodiments, the blade may be formed to define a first passageway that extends through the blade. The platform may be formed to define a second passageway that extends through the platform. The pin may be located in the first passageway and the second passageway. The first passageway may be partially offset radially from the second passageway relative to a longitudinal axis of the pin when the pin is located in the first passageway and the second passageway. In some embodiments, the second passageway may open into the blade-receiving passageway. 
     According to another aspect of the present disclosure, a method may include a number of steps. The method may include providing a blade comprising ceramic matrix composite materials, a platform comprising ceramic matrix composite materials, and a pin, the blade formed to include a first passageway that extends through the blade, and the platform formed to include a blade-receiving passageway that extends through the platform and a second passageway that extends through the platform, inserting the blade through the blade-receiving passageway formed in the platform, and locating the pin in the first passageway and the second passageway to couple the platform with the blade to provide a blade assembly. 
     In some embodiments, the locating step comprises bicasting the pin with the blade and the platform. In some embodiments, the method may further comprise infiltrating a blade mesh to form the blade before the inserting step and infiltrating a platform mesh to form the platform before the inserting step. 
     These and other features of the present disclosure will become more apparent from the following description of the illustrative embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is cutaway view of a gas turbine engine that includes a fan, a compressor, a combustor, and a turbine, the turbine includes a plurality of turbine wheels, and each turbine wheel includes a disk and a plurality of ceramic matrix composite blade assemblies coupled to the disk as shown in  FIGS. 2 and 3 ; 
         FIG. 2  is an exploded view of a turbine wheel included in the turbine of the gas turbine engine of  FIG. 1  showing the disk, one of the blades, a platform that is formed separate from the blade, and a pin configured to couple the platform with the blade to form a turbine blade assembly; 
         FIG. 3  is a front elevation view of the turbine wheel of  FIG. 1  showing a pair of adjacent blades wherein pins extend through each respective blade and platform to couple the components together and to form blade assemblies, and further showing that adjacent platforms are configured to interlock with one another; 
         FIG. 4  is a front elevation view similar to  FIG. 3  showing pins with different cross-sectional shapes which may be incorporated into the turbine blade assembly; 
         FIG. 5  is a front elevation view of a turbine wheel showing a blade, a platform, and a pin that extends in a circumferential direction through the blade and platform to form a blade assembly; and 
         FIG. 6  is a side elevation view of the turbine wheel of  FIG. 5  showing the pin located in the blade and the platform to form the blade assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments illustrated in the drawings and specific language will be used to describe the same. 
     A blade assembly  25  in accordance with the present disclosure is included in a turbine  18  of an illustrative gas turbine  10  as shown in  FIG. 1 . As show in  FIGS. 2 and 3 , the blade assembly  25  includes a blade  26 , a platform  28 , and a pin  30 . The platform  28  is formed separate from the blade  26  and arranged around the blade  26  to form a portion of a flow path for hot, high-pressure combustion gasses passing through the turbine  18 . The pin  30  is located in the blade  26  and the platform  28  to couple the platform  28  with the blade  26  as shown in  FIG. 3 . The blade  26  and platform  28  comprise ceramic material, but are formed separately and are not substantially co-infiltrated with matrix materials. Accordingly, the pin  30  is the primary coupler of the blade assembly  25 . 
     The blade assembly  25  is coupled with a disk  24  included in a turbine wheel  22  of the turbine  18  as shown in  FIG. 3 . The disk  24  is arranged about a central axis  20  of the gas turbine engine  10  and formed to include a plurality of slots  38 . The slots  38  extend through the disk  24 . Each blade assembly  25  is located in one of the slots  38  and extends radially outward away from the disk  24  as suggested in  FIG. 3 . 
     The gas turbine engine  10  designed to include the blade assembly  25  includes a fan  12 , a compressor  14 , a combustor  16 , and the turbine  18  as shown in  FIG. 1 . The compressor  14  compresses and delivers air to the combustor  16 . The combustor  16  mixes fuel with the compressed air received from the compressor  14  and ignites the fuel. The hot, high-pressure gasses from the burning fuel are directed into the turbine  18  where the turbine blades  26  of the turbine  18  extract work to drive the compressor  14  and the fan  12 . In other embodiments, the gas turbine engine  10  may include a shaft, turboprop, or gearbox in place of fan  12 . 
     In the illustrative embodiment, the turbine  18  includes turbine wheels  22 , as shown in  FIG. 1 , that are configured to rotate about a central axis  20  of the gas turbine engine  10  during operation of the gas turbine engine to drive the compressor  14  and the fan  12 . Each turbine wheel  22  includes the disk  24  and a plurality of blade assemblies  25 . Each blade assembly  25  includes the blade  26 , the platform  28 , and the pin  30  as suggested in  FIGS. 2 and 3 . 
     The disk  24  is arranged about the central axis  20  as suggested in  FIGS. 1 and 2 . The disk  24  includes a forward side  32 , an aft side  34  spaced apart axially from the forward side  32 , and an outer diameter  36  that extends between the forward side  32  and the aft side  34 . The disk  24  is formed to include the plurality of slots  38  that extend through the disk  24  in a generally axial direction from the forward side  32  to the aft side  34  of the disk  24  and inwardly in a radial direction from the outer diameter  36  of the disk toward the central axis  20 . The disk comprises metallic material in the illustrative embodiments. 
     The disk  24  includes an annular body  40  and a plurality of disk posts  42  that extend radially outward away from the body  40  as shown in  FIGS. 2-4 . The body  40  and the plurality of disk posts  42  cooperate to define the plurality of slots  38  formed in the disk  24 . 
     The blade  26  includes a root  44  and an airfoil  46  coupled to the root  44  as shown, for example, in  FIG. 2 . The root  44  is located in one of the slots  38  to couple the blade  26  with the disk  24  as shown in  FIG. 3 . The airfoil  46  extends outwardly away from the root  44  in a radial direction. In the illustrative embodiment, the root  44  and the airfoil  46  are integrally formed to provide a monolithic component. 
     The airfoil  46  includes a leading edge  48  and a trailing edge  50  spaced axially part from the leading edge  48  relative to the axis  20  as shown in  FIG. 2 . The airfoil  46  further includes a pressure side  52  and a suction side  54  spaced apart from the pressure side  52 . The pressure side  52  and the suction side  54  extend between and interconnect the leading edge  48  and the trailing edge  50 . The leading edge  48 , trailing edge  50 , pressure side  52 , and suction side  54  extend continuously to mate with the root  44 . Because the platform  28  is formed separate from the blade  26 , the pressure side  52  and the suction side  54  join with the root  44  and no portion of the blade  26  extends circumferentially or axially outward away from the root  44  in the illustrative embodiments. 
     The blade  26  is formed to include a first passageway  56  that extends through the blade  26  as shown in  FIG. 2 . In some embodiments, the first passageway  56  extends axially relative to the axis  20  through the blade  26  as shown in  FIGS. 2 and 3 . In other embodiments, the first passageway  56  extends circumferentially relative to the axis  20  through the blade  26  as shown in  FIGS. 4 and 5 . The first passageway  56  is formed in the root  44  of the blade  26 . In other embodiments, the first passageway  56  may be formed in the airfoil  46 . 
     The first passageway  56  is sized to receive the pin  30 . In some embodiments, the first passageway  56  is circular as shown in  FIG. 3 . In some embodiments, the first passageway  56  is a non-circular elongated slot as shown in  FIG. 6 . In some embodiments, the first passageway  56  is non-circular such as, for example, triangular, square  30 ′, star shaped  30 ″, elliptical, eccentric, etc. as shown and suggested in  FIG. 4 . The non-circular shapes may block rotation of the platform  28 . 
     The blade  26  comprises ceramic materials adapted to withstand the high temperature combustion gasses surrounding the blade  26 . Illustratively, the blade  26  comprises ceramic matrix composite materials. In some embodiments, the blades  26  are formed from metallic materials. 
     The platform  28  is arranged about the blade  26  to define the flow path around the airfoil  46  of the blade  26  as shown in  FIG. 3 . As a result, the platform  28  resists movement of the hot, high-pressure gasses of the turbine  18  toward the root  44  and minimizes thermal transfer of the hot, high-pressure gasses to the root  44  of the blade  26 . The platform  28  includes an outer radial surface  60 , an inner radial surface  62 , a forward side wall  64 , an aft side wall  66  spaced apart axially from the forward side wall  64 , a left side wall  68 , and a right side wall  70  spaced apart circumferentially from the left side wall  68  as shown in  FIGS. 2 and 3 . The inner radial surface  62  faces the disk  24 . The outer radial surface  60  is spaced apart radially from the inner radial surface  62 . The forward side wall  64  and the aft side wall  66  extend between and interconnect the outer radial surface  60  and the inner radial surface  62 . The left side wall  68  and the right side wall  70  extend between and interconnect the outer radial surface  60  and the inner radial surface  62 . 
     The inner radial surface  62  is spaced apart from the outer diameter  36  of the disk  24  to form an air gap  84  between the inner radial surface  62  and the outer diameter  36  as shown in  FIG. 3 . The air gap  84  may provide insulation and minimize the thermal load on the disk  24 . 
     The platforms  28  comprise ceramic materials adapted to withstand high temperature combustion gasses. Illustratively, the platform  28  comprises ceramic matrix composite materials. In some embodiments, the platforms  28  are formed from metallic materials. The platform  28  is formed independent of the blade  26 . The platform  28  and the blade  26  are not substantially co-infiltrated. 
     The platform  28  is formed to include a blade-receiving passageway  72  that extends radially through the outer radial surface  60  and the inner radial surface  62  of the platform  28  as shown in  FIG. 2 . A portion of the blade  26  is located in the blade-receiving passageway  72 . 
     The platform  28  is formed to include a second passageway  74  that extends through the platform  28  as shown in  FIG. 2 . The second passageway  74  extends axially through the forward side wall  64  and the aft side wall  66 . In some embodiments, the second passageway extends into at least one of the left side wall  68  and the right side wall  70 . The second passageway  74  is sized to receive the pin  30 . The second passageway  74  opens into the blade-receiving passageway  72  in illustrative embodiments. 
     In some embodiments, the second passageway  74  is circular as shown in  FIG. 3 . In some embodiments, the second passageway  74  is a non-circular elongated slot. In some embodiments, the second passageway  74  is non-circular such as, for example, triangular, square, star shaped, elliptical, eccentric, etc. as shown in  FIG. 4 . In the illustrative embodiment, the second passageway  74  and the first passageway  56  have similar shapes. In other embodiments, the second passageway  74  and the first passageway  56  have dissimilar shapes. 
     In illustrative embodiments, the platform  28  interlocks with adjacent platforms  28  as shown in  FIGS. 3 and 4 . The interlocking platforms  28  may block rotation of the platforms  28  about the pins  30 . The left side wall  68  is formed to include a cutout  78  that extends into the left side wall  68  in a circumferential direction relative to the central axis  20  toward the right side wall  70 . The right side wall  70  is formed to include a cutout  80  that extends circumferentially into the right side wall  70  toward the left side wall  68 . The cutouts  78 ,  80  are sized to receive the side wall  68 ,  70  of an adjacent platform  28 . 
     The cutouts  78 ,  80  may be formed toward the outer radial surface  60  in some platforms  28  and they may be formed toward the inner radial surface  62  in other platforms as shown in  FIGS. 3 and 4 . In other embodiments, one cutout  78 ,  80  may be formed toward the outer radial surface  60  and the other cutout  78 ,  80  may be formed toward the inner radial surface  62  of the platform  28 . 
     The pin  30  is located in the first passageway  56  and the second passageway  74  to couple the platform  28  with the blade  26  to provide the blade assembly  25  as shown in  FIG. 3 . The pin  30  extends into the platform  28  and the blade  26  in an axial direction relative to the central axis  20  as shown in  FIG. 3 . In some embodiments, the pin  30  extends into the platform  28  and the blade  26  in a circumferential direction relative to the central axis  20  as shown in  FIGS. 5 and 6 . In some embodiments, the first passageway  56  is partially offset radially from the second passageway  74  relative to the longitudinal axis of the pin  30  when the pin  30  is located in the first passageway  56  and the second passageway  74  as shown in  FIGS. 5 and 6 . The pin  30  may be brazed with or otherwise coupled with the blade  26  and the platform  28 . In some embodiments, the pin  30  is formed by bicast with the blade  26  and the platform  28 . 
     In some embodiments, the pin  30  is circular when viewed along a longitudinal axis of the pin  30  as shown in  FIG. 3 . In some embodiments, the pin  30  is non-circular when viewed along a longitudinal axis of the pin  30 . For example, the pin  30  may be triangular, square, star shaped, elliptical, eccentric, etc. as shown in  FIG. 4 . In the illustrative embodiment, the pin  30 , the second passageway  74 , and the first passageway  56  have similar shapes. In other embodiments, the pin  30 , the second passageway  74 , and the first passageway  56  have dissimilar shapes. 
     A method in accordance with the present disclosure includes a number of steps. The method includes providing the blade  26  comprising ceramic matrix composite materials, the platform  28  comprising ceramic matrix composite materials, and the pin  30 . The blade  26  is formed to include the first passageway  56  that extends through the blade  26 . The platform  28  is formed to include the blade-receiving passageway  72  that extends through the platform  28  and the second passageway  74  that extends through the platform  28 . The method includes inserting the blade  26  through the blade-receiving passageway  72  formed in the platform  28 . The method further includes locating the pin  30  in the second passageway  74  and the first passageway  56  to couple the platform  28  with the blade  26  to provide the blade assembly  25 . 
     The locating step may include bicasting the pin  30  with the blade  26  and the platform  28 . The method may further include locating the blade assembly  25  adjacent another blade assembly to cause the platform  28  to overlap and interlock with a portion of the other blade assembly. The method may include infiltrating a blade mesh to form the blade  26  before the inserting step. The method may include infiltrating a platform mesh to form the platform  28  before the inserting step. As such, the blade  26  and platform  28  are rigid before the inserting step. 
     Another embodiment of a blade assembly  225  in accordance with the present disclosure is shown in  FIGS. 5 and 6 . The blade assembly  225  is substantially similar to the blade assembly  25  shown in  FIGS. 2-4  and described herein. Accordingly, similar reference numbers in the  200  series indicate features that are common between the blade assembly  25  and the blade assembly  225 . The description of the blade assembly  25  is incorporated by reference to apply to the blade assembly  225 , except in instances when it conflicts with the specific description and the drawings of the blade assembly  225 . 
     A turbine wheel  222  includes a disk  224  and the blade assembly  225  as shown in  FIGS. 5 and 6 . The blade assembly  225  includes a blade  226 , a platform  228 , and a pin  230  as shown in  FIGS. 5 and 6 . The disk  224  is arranged about the central axis  20  of the gas turbine engine  10  and formed to include a plurality of slots  238  that extends through the disk  224 . The blade  226  is located in the one of the slots  238  and extends radially outward away from the disk  224 . The platform  228  is formed separate from the blade  226  and arranged around the blades  226  to form a portion of a flow path for gases to pass through the turbine  218 . The pin  230  is located in the blade  226  and platform  228  to couple the platform  228  with the blade  226  as shown in  FIGS. 5 and 6 . 
     The blade  226  includes a root  244  and an airfoil  246  coupled to the root  244  as shown, for example, in  FIG. 5 . The root  244  is located in one of the slots  238  to couple the blade  226  with the disk  224 . The airfoil  246  extends outwardly away from the root  244  in a radial direction. In the illustrative embodiment, the root  244  and the airfoil  246  are integrally formed to provide a monolithic component. 
     The blade  226  is formed to include a first passageway  256  that extends through the blade  226  as shown in  FIG. 5 . The first passageway  256  extends circumferentially relative to the axis  20  through the blade  226  between a pressure side and a suction side of the blade  226 . The first passageway  256  is formed in the root  244  of the blade  226 . In other embodiments, the first passageway  256  may be formed in the airfoil  246 . 
     The first passageway  256  is sized to receive the pin  230 . The first passageway  256  is an elongated slot as shown in  FIG. 6 . In some embodiments, the first passageway  256  is circular. In some embodiments, the first passageway  256  is non-circular such as, for example, triangular, square, star shaped, elliptical, eccentric, etc. 
     The platform  228  includes an outer radial surface  260 , an inner radial surface  262 , a forward side wall  264 , an aft side wall  266  spaced apart axially from the forward side wall  264 , a left side wall  268 , and a right side wall  270  spaced apart circumferentially from the left side wall  268  as shown in  FIGS. 5 and 6 . The inner radial surface  262  faces the disk  224 . The outer radial surface  260  is spaced apart radially from the inner radial surface  262 . The forward side wall  264  and the aft side wall  266  extend between and interconnect the outer radial surface  260  and the inner radial surface  262 . The left side wall  268  and the right side wall  270  extend between and interconnect the outer radial surface  260  and the inner radial surface  262 . 
     The inner radial surface  262  is spaced apart from the outer diameter  236  of the disk  224  to form an air gap  284  between the inner radial surface  262  and the outer diameter  236  as shown in  FIG. 5 . The air gap  284  may provide insulation and minimize the thermal load on the disk  224 . 
     The platform  228  is formed to include a blade-receiving passageway  272  that extends radially through the outer radial surface  260  and the inner radial surface  262  of the platform  228 . A portion of the blade  226  is located in the blade-receiving passageway  272 . 
     The platform  228  is formed to include a second passageway  274  that extends through the platform  228  as shown in  FIG. 5 . The second passageway  274  is sized to receive the pin  230 . The second passageway  274  opens into the blade-receiving passageway  72  in illustrative embodiments. The second passageway  274  extends circumferentially through the left side wall  268  and the right side wall  270 . 
     The second passageway  274  is circular as shown in  FIG. 6 . In some embodiments, the second passageway  274  is circular or non-circular such as, for example, triangular, square, star shaped, elliptical, eccentric, etc. In the illustrative embodiment, the second passageway  274  and the first passageway  256  are offset radially when the pin is located in the first passageway  256  and the second passageway  274 . 
     In illustrative embodiments, the platform  228  interlocks with adjacent platforms  228  as suggested in  FIG. 5 . The interlocking platforms  228  may block rotation of the platforms  228  about the pins  230 . The left side wall  268  is formed to include a cutout  278  that extends into the left side wall  268  in a circumferential direction relative to the central axis  20  toward the right side wall  270 . The right side wall  270  is formed to include a pair of cutouts  280 ,  282  that extend circumferentially into the right side wall  270  toward the left side wall  268 . The cutouts  278 ,  280 ,  282  are sized to interlock with an adjacent platform  228 . The second passageway  274  is located in the cutout  278  in the embodiment shown in  FIG. 6 . 
     The pin  30  is located in the first passageway  256  and the second passageway  274  to couple the platform  228  with the blade  226  as shown in  FIG. 5 . The pin  230  extends into the platform  228  and the blade  226  in a circumferential direction relative to the central axis  20 . The pin  230  is circular when viewed along a longitudinal axis of the pin  230  as shown in  FIG. 6 . In some embodiments, the pin  230  is non-circular when viewed along a longitudinal axis of the pin  230 . For example, the pin  230  may be triangular, square, star shaped, elliptical, eccentric, etc. 
     Ceramic matrix composite (CMC) material may sustain higher temperatures as compared to traditional metal alloys. It may be desirable in gas turbine engines to use ceramic matrix composite materials where higher fuel efficiencies can be reached with higher temperatures. The turbine section of the engine experiences high temperatures, so ceramic matrix composites may provide a benefit in this area. In using a ceramic matrix composite blade, it may be desirable to separate the platform from the blade to ease manufacturing issues. The present disclosure provides a platform that is pinned to a ceramic matrix composite blade, but is not integrated into the blade during manufacture. 
     One embodiment of the present disclosure uses platforms that are pinned to each blade individually in the axial direction to minimize the amount of geometric complexity of the blade itself as shown in  FIG. 3 . This configuration may also reduce the amount of stress transferred to the blade through flexure of the platform. The platforms can be alternated between being scalloped on the upper and lower sides to eliminate free rotation of the platforms. In other embodiments, the platforms could use squared pins or steps in the blade itself. In other embodiments, the platforms are pinned to the blades in the radial direction to further prevent chatter due to blade flutter from aerodynamic loads as shown in  FIGS. 5 and 6 . 
     While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.