Patent Publication Number: US-10309240-B2

Title: Method and system for interfacing a ceramic matrix composite component to a metallic component

Description:
BACKGROUND 
     This description relates to a composite nozzle assembly, and, more particularly, to a method and system for interfacing a ceramic matrix composite component to a metallic component in a gas turbine engine. 
     At least some known gas turbine engines include a core having a high pressure compressor, combustor, and high pressure turbine (HPT) in serial flow relationship. The core engine is operable to generate a primary gas flow. The high pressure turbine includes annular arrays (“rows”) of stationary vanes or nozzles that direct the gases exiting the combustor into rotating blades or buckets. Collectively one row of nozzles and one row of blades make up a “stage”. Typically two or more stages are used in serial flow relationship. These components operate in an extremely high temperature environment, and may be cooled by air flow to ensure adequate service life. 
     HPT nozzles are often configured as an array of airfoil-shaped vanes extending between annular inner and outer bands which define the primary flowpath through the nozzle. Due to operating temperatures within the gas turbine engine, materials having a low coefficient of thermal expansion are used. For example, to operate effectively in such adverse temperature and pressure conditions, ceramic matrix composite (CMC) materials may be used. These low coefficient of thermal expansion materials have higher temperature capability than similar metallic parts, so that, when operating at the higher operating temperatures, the engine is able to operate at a higher engine efficiency. However, such ceramic matrix composite (CMC) have mechanical properties that must be considered during the design and application of the CMC. CMC materials have relatively low tensile ductility or low strain to failure when compared to metallic materials. Also, CMC materials have a coefficient of thermal expansion which differs significantly from metal alloys used as restraining supports or hangers for CMC type materials. Therefore, if a CMC component is restrained and cooled on one surface during operation, stress concentrations can develop leading to a shortened life of the segment. 
     To date nozzles formed of CMC materials have experienced localized stresses that have exceeded the capabilities of the CMC material, leading to a shortened life of the nozzle. The stresses have been found to be due to moment stresses imparted to the nozzle and associated attachment features, differential thermal growth between parts of differing material types, and loading in concentrated paths at the interface between the nozzle and the associated attachment features. 
     BRIEF DESCRIPTION 
     In one embodiment, an airfoil assembly for a gas turbine engine is formed of a ceramic matrix composite (CMC) material and includes a forward end and an aft end with respect to an axial direction of the gas turbine engine. The airfoil assembly further includes a radially outer end component including a radially outwardly-facing end surface having a non-compression load-bearing feature extending radially outwardly from the outwardly-facing end surface and formed integrally with the outer end component. The feature is configured to mate with a complementary feature formed in a radially inner surface of a first airfoil assembly support structure. The feature is selectively positioned orthogonal to a force imparted into the airfoil assembly. The airfoil assembly also includes a radially inner end component, and a hollow airfoil body extending between the inner and outer end components. The airfoil body is configured to receive a strut couplable at a first end to the first airfoil assembly support structure. 
     In another embodiment, a method of transferring load from a ceramic matrix composite (CMC) vane assembly to a metallic vane assembly support member includes providing the CMC vane assembly wherein the vane assembly includes a radially outer end component including a radially outwardly facing surface having one or more radially outwardly extending load transfer features. The vane assembly further includes, a radially inner end component, and an airfoil body extending between the inner and outer end components. The method further includes engaging the radially outer end component to at least one of a plurality of metallic vane assembly support members spaced circumferentially about a gas flow path. The vane assembly support members including one or more load receiving features shaped complementary to the load transfer features. The load transfer feature includes a wedge-shaped cross-section. 
     In yet another embodiment, a gas turbine engine includes an inner support structure formed of a first metallic material, the inner support structure including a strut, the strut including a first mating end, a second opposing mating end and a strut body extending radially between the first mating end and the second mating end. The gas turbine engine further includes an outer support structure formed of a second metallic material and an airfoil assembly including a ceramic matrix composite (CMC) material and extending between the inner support structure and the outer support structure. The airfoil assembly includes a radially outer end component including a radially outwardly-facing end surface having a non-compression load-bearing feature extending radially outwardly from the outwardly-facing end surface and formed integrally with the outer end component. The feature is configured to mate with a complementary feature formed in a radially inner surface of the outer support structure. The feature is selectively positioned orthogonally to a force imparted into the radially outwardly-facing end surface. The airfoil assembly also includes a radially inner end component, and a hollow airfoil body extending between the radially outer end component and radially inner end component. The airfoil body is configured to receive a strut couplable at a first end to the outer support structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-13  show example embodiments of the method and apparatus described herein. 
         FIG. 1  is a schematic illustration of an exemplary gas turbine engine. 
         FIG. 2  is a perspective view of a nozzle ring in accordance with an example embodiment of the present disclosure. 
         FIG. 3  is a partially exploded view of nozzle segment assemblies in accordance with an example embodiment of the present disclosure from a forward perspective looking aft. 
         FIG. 4  is another partially exploded view of nozzle segment assemblies also from a forward perspective looking aft. 
         FIG. 5  is a perspective view of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 6  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 7  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 8  is a perspective view of nozzle segment assembly as shown in  FIG. 7  mated to outer band using tab and a boss formed in outer band. 
         FIG. 9  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 10  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 11  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 12  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 13  is a perspective view of another embodiment of nozzle segment assembly including radially outwardly-facing end surface. 
         FIG. 14  is a flow diagram of a method of transferring load from a ceramic matrix composite (CMC) vane assembly to a metallic vane assembly support member. 
         FIG. 15  is a partially exploded view of the nozzle segment assemblies in accordance with another example embodiment of the present disclosure from a forward perspective looking aft. 
         FIG. 16  is another partially exploded view of the nozzle segment assemblies from a side perspective looking circumferentially. 
     
    
    
     Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of the disclosure. These features are believed to be applicable in a wide variety of systems including one or more embodiments of the disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein. 
     DETAILED DESCRIPTION 
     Embodiments of this disclosure describe nozzle segment assemblies that include an airfoil extending between inner and outer bands that are formed of a composite matrix material (CMC). The CMC material has a temperature coefficient of expansion that is different than the hardware used to support the CMC nozzle segment assemblies. Moreover, the CMC has material properties that tend to limit its ability to withstand forces in certain directions, for example, in a tensile direction or directions in which a tensile component is present, such as, but not limited to twisting or bending directions. 
     To interface the CMC nozzle segment assemblies to their respective support structure, which is metallic, new structures are described which permit the CMC nozzle segment assemblies to withstand the high temperature and hostile environment in a gas turbine engine turbine flow path. 
     The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to analytical and methodical embodiments of transmitting loads from one component to another. 
     Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings. 
     As used herein, the terms “axial” or “axially” refer to a dimension along a longitudinal axis of an engine. The term “forward” used in conjunction with “axial” or “axially” refers to moving in a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term “aft” used in conjunction with “axial” or “axially” refers to moving in a direction toward the rear of the engine. 
     As used herein, the terms “radial” or “radially” refer to a dimension extending between a center longitudinal axis of the engine and an outer engine circumference. 
     All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary. 
     The following description refers to the accompanying drawings, in which, in the absence of a contrary representation, the same numbers in different drawings represent similar elements. 
       FIG. 1  is a schematic illustration of an exemplary gas turbine engine  100 . Engine  100  includes a low pressure compressor  112 , a high pressure compressor  114 , and a combustor assembly  116 . Engine  100  also includes a high pressure turbine  118 , and a low pressure turbine  120  arranged in a serial, axial flow relationship on respective rotors  122  and  124 . Compressor  112  and turbine  120  are coupled by a first shaft  126 , and compressor  114  and turbine  118  are coupled by a second shaft  128 . 
     During operation, air flows along a central axis  115 , and compressed air is supplied to high pressure compressor  114 . The highly compressed air is delivered to combustor  116 . Exhaust gas flow (not shown in  FIG. 1 ) from combustor  116  drives turbines  118  and  120 , and turbine  120  drives fan or low pressure compressor  112  by way of shaft  126 . Gas turbine engine  100  also includes a fan or low pressure compressor containment case  140 . 
       FIG. 2  is a perspective view of a nozzle ring  200  in accordance with an example embodiment of the present disclosure. In the example embodiment, nozzle ring  200  may be located within high pressure turbine  118  and/or low pressure turbine  120  (shown in  FIG. 1 ). Nozzle ring  200  is formed of one or more nozzle segment assemblies  202 . Nozzle segment assemblies  202  direct combustion gases downstream through a subsequent row of rotor blades (not shown) extending radially outwardly from supporting rotor  122  or  124  (shown in  FIG. 1 ). Nozzle ring  200  and plurality of nozzle segment assemblies  202  defining nozzle ring  200  facilitate extracting energy by rotor  122  or  124  (shown in  FIG. 1 ). Additionally, nozzle ring  200  may be used in high pressure compressor  114  which may be either of a high pressure or low pressure compressor. Segment assemblies  202  include an inner band  204  and an outer band  216  and a plurality of struts  208  (not shown in  FIG. 2 ) extending through nozzle airfoils  210 . Inner band  204  and outer band  216  extend circumferentially 360 degrees about engine axis  115 . 
     Nozzle ring  200  is formed of a plurality of nozzle segment assemblies  202  each of which includes an inner support structure  212 , at least one nozzle airfoil  210  and a hanger or outer band  216 . Strut  208  carries load from the radially inward side of nozzle segment assembly  202  at inner support structure  212  to the radially outward side at outer band  216  where load is transferred to a structure of engine  100 , such as, but not limited to a casing of engine  100  and mechanically supports nozzle airfoil  210 . Strut  208  may be connected to at least one of inner support structure  212  and outer band  216  by, for example, but not limited to, bolting, fastening, capturing, combinations thereof and being integrally formed. 
       FIG. 3  is a partially exploded view of nozzle segment assemblies  202  in accordance with an example embodiment of the present disclosure from a forward perspective looking aft.  FIG. 4  is another partially exploded view of nozzle segment assemblies  202  also from a forward perspective looking aft. In the example embodiment, nozzle segment assembly  202  includes an inner support structure  212  formed of a first metallic material. Inner support structure  212  includes a strut  208  that is couplable to inner support structure  212 , is formed integrally with inner support structure  212 , or may be coupled to inner support structure  212  during assembly of nozzle segment assembly  202 . Strut  208  may be hollow and may each have at least one internal wall to enhance a stiffness of strut  208 . Strut  208  includes a first mating end  206  (hidden by inner support structure  212  in  FIGS. 3 and 4 ), a second opposing mating end  207 , and a strut body  209  extending radially therebetween. In the example embodiment, strut body  209  is cylindrically-shaped. In various embodiments, strut body  209  has non-circular cross-section, for example, but, not limited to, oval, oblong, polygonal, or combinations thereof. Nozzle segment assembly  202  also includes a radially outer band  216  formed of a second metallic material. In the example embodiment, the first and second metallic material are the same material such as, but not limited to a nickel-based superalloy, an intermetallic material such as gamma titanium aluminide, or other alloy that exhibits resistance to high temperatures. Inner support structure  212 , outer band  216 , strut  208 , and other metallic components of the assembly may all be formed of the same material or may be formed of different materials that are able to perform the functions described herein. 
     Nozzle airfoil  210  is formed of a material having a low coefficient of thermal expansion, such as for example, ceramic matrix composite (CMC) material. Nozzle airfoil  210  extends between inner band  204  and outer band  216 . Outer band  216  includes a radially outwardly-facing end surface  302  having a non-compression load-bearing feature  304  extending radially outwardly from outwardly-facing end surface  302  and formed integrally with outer band  216 . Feature  304  is configured to mate with a complementary feature  306  formed in a radially inner surface  308  of outer support structure  214 . Feature  304  is selectively positioned orthogonally to a force imparted into nozzle airfoil  210 . In various embodiments, inner band  204  includes a radially inwardly-facing end surface  310  having a non-compression load-bearing feature (not shown) extending radially inwardly from radially inwardly-facing end surface  310  and formed integrally with inner band  204 . The feature extending from radially inwardly-facing end surface  310  is configured to mate with a complementary feature  312  formed in a radially outer surface  314  of inner band  204 . 
       FIG. 5  is a perspective view of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a wedge flange  502  that includes a whistle notch  504 . Wedge flange  502  includes a built-up area  506  along an aft side  508  of surface  302 . Wedge flange  502  increases in thickness  510  from a forward starting point  512  towards aft side  508 . Wedge flange  502  is formed of CMC during a layup phase of manufacturing and is therefore an integral extension of surface  302  in an outward radial direction  514 . In various embodiments, notch  504  is formed by machining surface  302  during manufacturing. Alternatively, notch  504  is formed during the layup phase. Notch  504  is configured to a complementarily-shaped feature (not shown) extending radially inwardly from radially inner surface  308  of inner support structure  212 . A face  516  of notch  504  is configured to receive a tangential load from the feature (not shown) extending radially inwardly from radially inner surface  308 . Face  516  may be oriented axially, as illustrated, or may be oriented at a positive or negative angle  518  with respect to axis  15  (shown in  FIG. 1 ) to receive loads that are not only tangential, but that also include an axial component. 
       FIG. 6  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, two non-compression load-bearing features  304  are embodied in an axial wedge flange  602  that is oriented orthogonally to an axial direction  604  and a tangential flange  606 . Axial wedge flange  602  includes a face  608  oriented towards axial direction  604  and is configured to transmit axially-oriented loads to a complementarily-shaped feature (not shown) extending radially inwardly from radially inner surface  308  of inner support structure  212 . In the example embodiment, tangential flange  606  includes a rectangular cross-section and a first face  610  and a second face  612  configured to transmit loads with a tangential component to a complementarily-shaped feature (not shown) extending radially inwardly from radially inner surface  308  of inner support structure  212 . A relative orientation and position of axial wedge flange  602  and tangential flange  606  are selected based on determined forces that will be generated in nozzle airfoil  210  during operation. 
       FIG. 7  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a radially outwardly extending tab  702 . Tab  702  includes a first face  704  and an opposing second face  706 . An aperture  708  is configured to receive a pin (not shown in  FIG. 7 ). Faces  704  and  706  are positioned such that a load is transmitted orthogonally to faces  704  and  706 . Tab  702  is configured to be received in a complementarily-shaped boss (not shown in  FIG. 7 ) extending from radially inner surface  308  of outer band  216 . In some embodiments, the boss also includes one or more apertures aligned with aperture  708  when nozzle segment assembly  202  is assembled to for example, outer band  216 . A pin (not shown in  FIG. 7 ) inserted through aperture  708  and the apertures in the boss permit transfer of radial loads to outer band  216  through the pin (not shown in  FIG. 7 ). 
       FIG. 8  is a perspective view of nozzle segment assembly  202  as shown in  FIG. 7  mated to outer band  216  using tab  702  and a boss  802  formed in outer band  216 . In the example embodiment, a pin  804  is optionally inserted through aperture  708  (shown in  FIG. 7 ) and one or more apertures  806  in boss  802 . Tab  702 , boss  802 , and pin  804  are configured to transmit and receive loads in an axial direction  808 , a tangential direction  810 , and a radial direction  812 . Faces of tab  702 , boss  802 , and pin  804  may be squarely aligned in axial direction  808  and tangential direction  810  or may be aligned at an angle with respect to axial direction  808  and tangential direction  810  to transmit loads having axial and tangential components. 
       FIG. 9  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a hook member  902  including a radially outwardly extending ramp portion  904  and an opposing concave portion  906 . Hook member  902  is configured to mate with a complementarily-shaped feature formed in radially inner surface  308  of inner support structure  212 . 
       FIG. 10  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a compound axial wedge flange  1002  in combination with a tangential notch  1003 . Compound axial wedge flange  1002  includes a first wedge flange  1004  having a first axial face  1006  and a second wedge flange  1008  having a second axial face  1010 . Tangential notch  1003  includes a tangential face  1012  and an axial face  1014 . Each of faces  1003 ,  1006 , and  1014  are configured to transmit a load in an axial direction  1016  to a complementarily-shaped feature extending from radially inner surface  308  (shown in  FIG. 3 ) of outer band  216  (shown in  FIG. 3 ). Face  1012  is configured to transmit a load in a tangential direction  1018  to a complementarily-shaped feature extending from radially inner surface  308  (shown in  FIG. 3 ) of outer band  216  (shown in  FIG. 3 ). 
       FIG. 11  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a tangential flange  1102  that engages a tangential face loading pivot  1104 . Tangential flange  1102  is similar to tangential flange  606  and in some embodiments is identical to tangential flange  606 . In various embodiments, tangential face loading pivot  1104  is formed of metal and is pivotably coupled to, for example, a complementarily-shaped pin (not shown) extending from radially inner surface  308  (shown in  FIG. 3 ) of outer band  216  (shown in  FIG. 3 ). In the example embodiment, radially outwardly-facing end surface  302  also includes an axial wedge flange  1106  that includes an aft-facing axial face  1108 . Axial wedge flange  1106  may be transmitting a strictly axial load through aft-facing axial face  1108  for, for example, sealing purposes. Because of a particular geometry between nozzle segment assembly  202  and adjacent nozzle segment assemblies  202  the load may not be able to be reduced to a strictly tangential load, tangential flange  1102  and tangential face loading pivot  1104  is used to interface across the entire surfaces of faces  1110  and  1112 . If load were to twist to transmit from another direction, tangential face loading pivot  1104  would pivot to continue to spread the load across faces  1110  and  1112 . 
       FIG. 12  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a pin slot flange  1202 , having a radially oriented pocket  1204  configured to engage a complementarily-shaped tangential pin  1206  extending from radially inner surface  308  (shown in  FIG. 3 ) of outer band  216  (shown in  FIG. 3 ). The combination of pin slot flange  1202  and tangential pin  1206  operates substantially similarly to tangential flange  1102  and tangential face loading pivot  1104  (both shown in  FIG. 11 ). Pin slot flange  1202  and tangential pin  1206  may be selected for use in combination with an axial wedge flange  1208  that includes an aft-facing axial face  1210 . In various embodiments, a plurality of pin slot flanges  1202  and tangential pins  1206  may be positioned and oriented to transmit all loads through surface  302 . For example, combinations of pin slot flanges  1202  and tangential pins  1206  may be positioned at several locations on surface  302  and axial wedge flange  1208  not be used. 
       FIG. 13  is a perspective view of another embodiment of nozzle segment assembly  202  including radially outwardly-facing end surface  302 . In the example embodiment, non-compression load-bearing feature  304  is embodied in a pressure-side wedge  1302 . Pressure-side wedge  1302  includes a plurality of contact pads  1304 . In the example embodiment, three contact pads  1304  are shown, however any number of contact pads may be used. Pressure-side wedge  1302  is positioned such that a tangential face  1306  coincides or overhangs a sidewall  1308  of an opening  1310  into a hollow interior of airfoil  210 . Such a position permits easier machining of contact pads  1304  during fabrication. Pads  1304  are configured to a complementarily-shaped feature extending from radially inner surface  308  (shown in  FIG. 3 ) of outer band  216  (shown in  FIG. 3 ). In the example embodiment, pads  1304  are formed of CMC material and are machined to increase local wear resistance. In various embodiments, pads  1304  may be formed of a metal or other material different from CMC and machined into tangential face  1306 . Tangential loads are transmitted through tangential face  1306  to outer band  216  (shown in  FIG. 3 ). 
       FIG. 14  is a flow diagram of a method  1400  of transferring load from a ceramic matrix composite (CMC) vane assembly to a metallic vane assembly support member. In the example embodiment, method  1400  includes providing  1402  the CMC vane assembly wherein the CMC vane assembly includes a radially outer end component includes a radially outwardly facing surface having one or more radially outwardly extending load transfer features, a radially inner end component, and an airfoil body extending therebetween. Method  1400  also includes engaging  1404  the radially outer end component to at least one of a plurality of metallic vane assembly support members spaced circumferentially about a gas flow path. The vane assembly support members include one or more load receiving features shaped complementary to the load transfer features, the load transfer feature including a wedge-shaped cross-section. 
       FIG. 15  is a partially exploded view of nozzle segment assemblies  202  in accordance with another example embodiment of the present disclosure from a forward perspective looking aft.  FIG. 16  is another partially exploded view of nozzle segment assemblies  202  from a side perspective looking circumferentially. In the example embodiment, nozzle segment assembly  202  includes an inner support structure  212  formed of a first metallic material. Inner support structure  212  includes a strut  208  that is couplable to inner support structure  212 , is formed integrally with inner support structure  212 , or may be coupled to inner support structure  212  during assembly of nozzle segment assembly  202 . Strut  208  may be hollow and may each have at least one internal wall to enhance a stiffness of strut  208 . Strut  208  includes a first mating end  206  (hidden by inner support structure  212  in  FIGS. 15 and 16 ), a second opposing mating end  207 , and a strut body  209  extending radially therebetween. In the example embodiment, strut body  209  is cylindrically-shaped. In various embodiments, strut body  209  has non-circular cross-section, for example, but, not limited to, oval, oblong, polygonal, or combinations thereof. Nozzle segment assembly  202  also includes a radially outer support structure  214  formed of a second metallic material. In the example embodiment, the first and second metallic material are the same material such as, but not limited to a nickel-based superalloy, an intermetallic material such as gamma titanium aluminide, or other alloy that exhibits resistance to high temperatures. Inner support structure  212 , outer support structure  214 , strut  208 , and other metallic components of the assembly may all be formed of the same material or may be formed of different materials that are able to perform the functions described herein. 
     Nozzle airfoil  210  is formed of a material having a low coefficient of thermal expansion, such as for example, ceramic matrix composite (CMC) material. Nozzle airfoil  210  extends between inner band  204  and outer band  216 . Outer band  216  includes a radially outwardly-extending end surface  302  having an aft facing flange surface  1504  extending radially outwardly from outwardly-facing end surface  1502  and formed integrally with outer band  216 . Flange surface  1504  is configured to mate with a complementary flange surface  1506  formed in a radially inner surface  308  of outer support structure  214 . A seal between outer band  216  and outer support structure  214  is formed at the mating surfaces of flange surface  1504  and flange surface  1506  when nozzle segment assemblies  202  is assembled. 
     Nozzle segment assemblies  202  also includes a first radial retention feature  1508  that includes strut body  209 , mating end  207 , a mating end receptacle  1510 , and a first retention pin  1512 . When assembled, mating end  207  is inserted into receptacle  1510  such that an aperture  1514  through mating end  207  and an aperture  1516  through mating end receptacle  1510 . First retention pin  1512  is inserted through apertures  1514  and  1516  to retain nozzle segment assemblies  202  radially. 
     Nozzle segment assemblies  202  also includes a second radial retention feature  1518  that includes one or more radial retention pins  1520  and associated apertures  1522  in inner band  204 . Radial retention pins  1520  extend from a radial outer side of inner band  204  within hollow airfoil  210 , through inner band  204 , and into inner support structure  212  using associated apertures  1522 . The purpose of these pins is to sandwich inner band  204  to prevent nozzle airfoils  210  from floating radially outwardly due to an a mismatch between strut body  209  and nozzle airfoils  210  causing a radial gap to open. Allowing nozzle airfoils  210  to float in this opened gap would cause undesirable flow path steps. Radial retention pins  1520  ensure that nozzle airfoils  210  are always loaded to inner support structure  212 . 
     Embodiments of the present disclosure have been described and illustrated showing various ways CMC nozzle segment assembly  202  can interface with strut  208 , inner support structure  212 , and outer band  216 , with different configurations having certain benefits or detriments such as sealing, leakage, and stresses. In some embodiments, CMC nozzle segment assembly  202  is mounted to a metal strut to react loads to the stator. The various mounting features include a “wange” or wedge flange, which is a reinforced flange that can transmit axial or tangential load, a “tab” is a feature for transmitting primarily tangential load, a “whistle notch” is a notch or cutout in inner band  204  or outer band  216  and is primarily a tangential load feature, a flange notch, which is also primarily a tangential load feature, a “pad” is a feature inside the nozzle cavity that loads against the strut  208 , and a “pin” that is a feature that has holes or slots in inner band  204  or outer band  216  that loads to the strut through the pins. 
     It will be appreciated that the above embodiments that have been described in particular detail are merely example or possible embodiments, and that there are many other combinations, additions, or alternatives that may be included. 
     Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. 
     The above-described embodiments of a method and system of transferring load from a ceramic matrix composite (CMC) vane assembly to a metallic vane assembly support member provides a cost-effective and reliable means for spreading load transferred from the CMC vane assembly to the metallic vane assembly support member over a larger area than with traditional metallic vane assemblies. More specifically, the method and system described herein facilitate orienting and positioning load transmitting features on the CMC vane assembly with respect to load receiving features on the metallic vane assembly support member. As a result, the methods and systems described herein facilitate extending a service life of the vane assemblies in a cost-effective and reliable manner. 
     This written description uses examples to describe the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.