Abstract:
A component according to an exemplary aspect of the present disclosure includes, among other things, a shell defining an interior, a spar extending into the interior and a first flange attached to the spar. The spar is configured to pivot to change a positioning of the shell.

Description:
[0001]    This invention was made with government support under Contract No. N00014-09-D-0821, awarded by the United States Navy. The government has certain rights in this invention. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates to a gas turbine engine, and more particularly to a variable area gas turbine engine component having a spar pivotable to change a rotational positioning of a shell. 
         [0003]    Gas turbine engines typically include at least a compressor section, a combustor section and a turbine section. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads. 
         [0004]    The compressor and turbine sections typically include alternating rows of rotating blades and stationary vanes. The rotating blades impart or extract energy from the airflow that is communicated through the gas turbine engine, and the vanes direct the airflow to a downstream row of blades. The vanes can be manufactured to a fixed flow area that is optimized for a single flight point. It is also possible to alter the flow area between two adjacent vanes by providing a variable vane that rotates about a given axis to vary the flow area. 
       SUMMARY 
       [0005]    A component according to an exemplary aspect of the present disclosure includes, among other things, a shell defining an interior, a spar extending into the interior and a first flange attached to the spar. The spar is configured to pivot to change a positioning of the shell. 
         [0006]    In a further non-limiting embodiment of the foregoing component, the spar is comprised of a first material and the shell is comprised of a second material that is different from the first material. 
         [0007]    In a further non-limiting embodiment of either of the foregoing components, the first material is a metal and the second material is a ceramic matrix composite. 
         [0008]    In a further non-limiting embodiment of any of the foregoing components, a shaft extends from the first flange in a direction opposite from the spar. 
         [0009]    In a further non-limiting embodiment of any of the foregoing components, the shell is an airfoil sheath. 
         [0010]    In a further non-limiting embodiment of any of the foregoing components, the first flange extends outside of the shell. 
         [0011]    In a further non-limiting embodiment of any of the foregoing components, the first flange is received within a pocket formed in a first platform. 
         [0012]    In a further non-limiting embodiment of any of the foregoing components, a second platform is located on an opposite side of the shell from the first platform. 
         [0013]    In a further non-limiting embodiment of any of the foregoing components, the spar includes a plurality of cooling openings. 
         [0014]    In a further non-limiting embodiment of any of the foregoing components, the spar is moveable within the interior. 
         [0015]    In a further non-limiting embodiment of any of the foregoing components, the spar is connected to a second flange opposite from the first flange. 
         [0016]    In a further non-limiting embodiment of any of the foregoing components, a plurality of stand-offs extend between the spar and the shell. 
         [0017]    In a further non-limiting embodiment of any of the foregoing components, the plurality of stand-offs protrude from one of the spar and the shell and extend toward the other of the spar and the shell. 
         [0018]    A vane assembly according to an exemplary aspect of the present disclosure including, among other things, a first platform, a second platform and a variable vane that that extends between the first platform and the second platform. The variable vane includes an airfoil sheath comprised of a first material and a spar extending inside of the airfoil sheath and comprised of a second material. 
         [0019]    In a further non-limiting embodiment of the foregoing assembly, the first material is different from the second material. 
         [0020]    In a further non-limiting embodiment of either the foregoing assemblies, the variable vane is part of a turbine vane assembly. 
         [0021]    A method according to another exemplary aspect of the present disclosure includes, among other things, inserting a spar inside of a shell of a component, communicating a gas load across the shell and pushing the shell onto the spar in response to the step of communicating the gas load. 
         [0022]    In a further non-limiting embodiment of the foregoing method, the method includes pivoting the spar and changing a positioning of the shell in response to the step of pivoting. 
         [0023]    In a further non-limiting embodiment of either of the foregoing methods, the step of inserting includes positioning the spar so that it is freely movable relative to the shell. 
         [0024]    In a further non-limiting embodiment of any of the foregoing methods, the method includes communicating structural loads through the spar and isolating the shell from the structural loads. 
         [0025]    The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  illustrates a schematic, cross-sectional view of a gas turbine engine. 
           [0027]      FIG. 2  illustrates a variable area component of a gas turbine engine. 
           [0028]      FIG. 3  illustrates an exploded view of  FIG. 2 . 
           [0029]      FIG. 4  illustrates portions of the component of  FIG. 2 . 
           [0030]      FIGS. 5A and 5B  illustrate cross-sectional views of a variable area component. 
           [0031]      FIG. 5C  illustrates a feature of a variable area component. 
           [0032]      FIG. 6  illustrates additional features of a variable area component. 
           [0033]      FIG. 7  illustrates another embodiment of a variable area component. 
           [0034]      FIG. 8  illustrates an exploded view of  FIG. 7 . 
           [0035]      FIG. 9  illustrates portions of the component of  FIG. 7 . 
           [0036]      FIGS. 10A and 10B  illustrate yet another exemplary variable area component. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    This disclosure is directed to a variable area gas turbine engine component that includes a spar that is pivotable to change a rotational positioning of a shell or airfoil sheath of the component. The spar may include a ductile substrate that is capable of absorbing structural loads directed through the variable area component, and the shell is a structure that is capable of withstanding relatively extreme temperature environments. These and other features are described in detail herein. 
         [0038]      FIG. 1  schematically illustrates a gas turbine engine  20 . The exemplary gas turbine engine  20  is a two-spool turbofan engine that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmenter section (not shown) among other systems for features. The fan section  22  drives air along one or more bypass flow paths B, while the compressor section  24  drives air along a core flow path C for compression and communication into the combustor section  26 . The hot combustion gases generated in the combustor section  26  are expanded through the turbine section  28 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to turbofan engines and these teachings could extend to other types of engines, including but not limited to, three-spool engine architectures. 
         [0039]    The gas turbine engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine centerline longitudinal axis A. The low speed spool  30  and the high speed spool  32  may be mounted relative to an engine static structure  33  via several bearing systems  31 . It should be understood that other bearing systems  31  may alternatively or additionally be provided. 
         [0040]    The low speed spool  30  generally includes an inner shaft  34  that interconnects a fan  36 , a low pressure compressor  38  and a low pressure turbine  39 . The inner shaft  34  can be connected to the fan  36  through a geared architecture  45  to drive the fan  36  at a lower speed than the low speed spool  30 . The high speed spool  32  includes an outer shaft  35  that interconnects a high pressure compressor  37  and a high pressure turbine  40 . In this embodiment, the inner shaft  34  and the outer shaft  35  are supported at various axial locations by bearing systems  31  positioned within the engine static structure  33 . 
         [0041]    A combustor  42  is arranged between the high pressure compressor  37  and the high pressure turbine  40 . A mid-turbine frame  44  may be arranged generally between the high pressure turbine  40  and the low pressure turbine  39 . The mid-turbine frame  44  can support one or more bearing systems  31  of the turbine section  28 . The mid-turbine frame  44  may include one or more airfoils  46  that extend within the core flow path C. 
         [0042]    The inner shaft  34  and the outer shaft  35  are concentric and rotate via the bearing systems  31  about the engine centerline longitudinal axis A, which is co-linear with their longitudinal axes. The core airflow is compressed by the low pressure compressor  38  and the high pressure compressor  37 , is mixed with fuel and burned in the combustor  42 , and is then expanded over the high pressure turbine  40  and the low pressure turbine  39 . The high pressure turbine  40  and the low pressure turbine  39  rotationally drive the respective high speed spool  32  and the low speed spool  30  in response to the expansion. 
         [0043]    Each of the compressor section  24  and the turbine section  28  may include alternating rows of rotor assemblies and vane assemblies (shown schematically) that carry airfoils that extend into the core flow path C. For example, the rotor assemblies can carry a plurality of rotating blades  25 , while each vane assembly can carry a plurality of vanes  27  that extend into the core flow path C. The blades  25  impart or extract energy (in the form of pressure) from the core airflow that is communicated through the gas turbine engine  20  along the core flow path C. The vanes  27  direct the core airflow to the blades  25  to either impart or extract energy. 
         [0044]      FIGS. 2, 3 and 4  illustrate a component  50  that can be incorporated into a gas turbine engine, such as the gas turbine engine  20  of  FIG. 1 . The component  50  may be a variable vane of either the compressor section  24  or the turbine section  28  of the gas turbine engine  20 . However, the component  50  could be employed in other sections of the gas turbine engine  20 . For example, the component  50  may be a segment of any vane or nozzle assembly of the gas turbine engine  20  in which it is desirable to turn and/or direct a hot gas stream toward a downstream location. 
         [0045]    The component  50  can be mechanically attached or otherwise linked to other segments and annularly disposed about the engine centerline longitudinal axis A (see  FIG. 1 ) to form a full ring vane or nozzle assembly. The full ring vane or nozzle assembly may include fixed vanes (i.e., static airfoils), variable vanes that rotate to alter a flow area associated with the vane or nozzle assembly (such as similar to the component  50  shown and described herein), or both. 
         [0046]    The exemplary component  50  may include a first platform  66 , a second platform  68  and a shell  52  that extends between the first platform  66  and the second platform  68 . The first platform  66  is positioned on an outer diameter side of the component  50  and the second platform  68  is positioned on an inner diameter side of the component  50  to establish outer and inner gas flow paths  72 ,  74  for communicating hot combustion gases along the core flow path C. 
         [0047]    The shell  52  extends in span across an annulus  70  (see  FIG. 2 ) between the first platform  66  and the second platform  68  and is movable relative thereto. In one embodiment, the shell  52  is an airfoil sheath. The shell  52  is not necessarily limited to the configuration illustrated by  FIGS. 2, 3 and 4 . For example, although a single shell  52  is illustrated, the component  50  could include additional shells or airfoil sheaths. 
         [0048]    The exemplary component  50  may additionally include a spar  54  that is connected to a first flange  56  and, optionally, a second flange  58 . The spar  54  is connectedly received by the first flange  56  and the second flange  58  at its opposite ends. 
         [0049]    In one embodiment, the shell  52  is a hollow component that defines an interior  60  (see  FIG. 3 ) which can receive a portion or the entirety of the spar  54 . The spar  54  may be inserted through the interior  60 , for example. As discussed in greater detail below, the spar  54  is pivotable in order to change a rotational positioning of the shell  52 . Changing the rotational positioning of the shell  52  alters the flow area between adjacent vane segments of a vane or nozzle assembly. Adjusting the flow area in this manner may increase the efficiency of the gas turbine engine  20 . 
         [0050]    The first platform  66  may include a hole  76  (see  FIG. 3 ) for inserting the spar  54  into the interior  60  of the shell  52 . The first flange  56  is received within a pocket  78  formed in a non-gas path surface  65  of the first platform  66 . In one embodiment, the pocket  78  and the first flange  56  embody a triangular shape, although other shapes are also contemplated. The first flange  56  substantially covers the hole  76  of the first platform  66  when received within the pocket  78 . 
         [0051]    If necessary, the second flange  58  is received relative to the second platform  68  and includes a pocket  80  (see  FIG. 3 ) that may receive a portion of the spar  54 . The second flange  58  may also include a sealing surface  82  for sealing relative to the second platform  68 . In one embodiment, the second flange  58  is positioned relative to the second platform  68  after the spar  54  is inserted through the shell  52 . 
         [0052]    Each of the first flange  56  and the second flange  58  may include a shaft  84  that protrudes from the first flange  56  and/or the second flange  58  in a direction away from the spar  54 . The flanges  56 ,  58  and the spar  54  may be pivoted about the shafts  84  in order to change a rotational positioning of the shell  52 . In other words, a pivot point of the flanges  56 ,  58  and the spar  54  extends through the shafts  84 . 
         [0053]    The spar  54  and flanges  56 ,  58  may be rotated about the shafts  84  in any known manner, including but not limited to, direct rotary actuation, a bell crank arm, a unison ring or a ring gear system. One non-limiting example of a ring gear system that could be utilized is illustrated in U.S. Pat. No. 8,240,983, the disclosure of which is incorporated herein by reference. 
         [0054]    A cooling fluid  86  may be directed through the spar  54  as necessary to cool the component  50 . In one embodiment, the spar  54  is hollow and includes a plurality of cooling openings  88 . The cooling fluid  86  may be communicated through an opening  79  in the first flange  56 , then through the hollow portion of the spar  54 , before purging through the cooling openings  88  to cool the inner walls  90  of the shell  52  (see  FIGS. 2, 3 and 6 ). 
         [0055]    In one embodiment, the shell  52  of the component  50  is made of a first material and the spar  54  is made of a second material. The first material and the second material may be different materials. For example, in one embodiment, the shell  52  is made of a ceramic matrix composite (CMC) and the spar  54  is made of a metallic material, such as a nickel alloy, molybdenum, or some other high temperature alloy. Other materials are also contemplated as within the scope of this disclosure, including other ceramic and metallic materials. 
         [0056]    As can be appreciated, by separating the component  50  into distinct parts, structural loads acting upon the component  50  may be directed through the spar  54 , while the shell  52  can simultaneously withstand relatively high temperature environments by virtue of its material makeup. In other words, the shell  52  is isolated from structural loads that may act on the component  50  by the spar  54 , and the spar  54  is isolated from the relatively hot gases communicated across the component  50  by the shell  52 . 
         [0057]      FIG. 4  illustrates the component  50  with the first platform  66  and the second platform  68  removed for clarity. A rotational axis RA extends through the shafts  84  of the first flange  56  and the second flange  58 . The first flange  56  and the second flange  58  may be rotated about the rotational axis RA to move the spar  54 , and as a consequence of this movement, change a rotational positioning RP of the shell  52 . 
         [0058]      FIGS. 5A, 5B, and 6  schematically illustrate moving the spar  54  to effectuate a change in a rotational positioning of the shell  52  of the component  50 . Changing the rotational positioning of the shell  52  changes a flow area associated with the component  50 . 
         [0059]      FIG. 5A  illustrates a relationship between the shell  52  and the spar  54  during an assembled configuration C 1  (i.e., prior to operation of the gas turbine engine). The spar  54  is moveable inside of the shell  52  and may or may not be in contact with an inner wall  90  of the shell  52 . 
         [0060]    The component  50  is illustrated during a second configuration C 2  which occurs during gas turbine engine operation in  FIG. 5B . During such operation, the shell  52  is pushed onto (i.e., into contact with) the spar  54 . A gas load  92  may push the shell  52  onto the spar  54 . In one embodiment, the gas load  92  is communicated against a leading edge  95  of the shell  52  to push the shell  52  against at least a leading edge  97  of the spar  54 . Of course, the shell  52  and the spar  54  may engage one another in many other manners, such as differential thermal growth, and at other locations. Once the shell  52  is sufficiently engaged relative to the spar  54 , the spar  54  may be pivoted to change the rotational positioning of the shell  52 . 
         [0061]    In one embodiment, illustrated in  FIG. 5C , a plurality of stand-offs  53  may extend between the spar  54  and the shell  52  to maintain impingement distances between the spar  54  and the shell  52 . For example, the stand-offs  53  may protrude from the spar  54  or the shell  52  to maintain a spacing between an outer wall  91  of the spar  54  and an inner wall  90  of the shell  52 . Alternatively, the stand-offs  53  may be separate components that are attached to the shell  52  and the spar  54 . Maintaining the spacing between the shell  52  and spar  54  ensures proper impingement of the cooling fluid  86  through the cooling openings  88  and onto the inner walls  90  (see  FIG. 6 ). The stand-offs  53  may also aid in changing the positioning of the shell  52 . The size, shape, placement and overall configuration of the stand-offs  53  can vary. In other words, the configuration shown in  FIG. 5C  is not intended to be limiting. 
         [0062]      FIG. 6  schematically illustrates changing the positioning, such as the rotational positioning, of the shell  52 . The first flange  56  and the second flange  58  are pivoted in a direction P (either clockwise or counterclockwise) to move the flanges  56 ,  58  about the rotational axis RA. Because the shell  52  has been moved (i.e., pushed or sucked) onto the spar  54  via the gas load  92 , pivoting the spar  54  changes the rotational positioning of the shell  52  relative to the gas flow paths  72 ,  74  defined by the first platform  66  and the second platform  68 . The spar  54  can rotate the shell  52  without the shell  52  interfering with the first platform  66  or the second platform  68  (platforms are removed in  FIG. 6 ). 
         [0063]      FIG. 6  additionally illustrates communication of the cooling fluid  86  through the cooling openings  88  of the spar  54  and into interior  60  to cool the inner walls  90  of the shell  52 . The component  50  may or may not be cooled with such a dedicated cooling fluid. 
         [0064]      FIGS. 7, 8 and 9  illustrate another exemplary embodiment of a component  150  that can be incorporated for use in a gas turbine engine. In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of 100 or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding original elements. For ease of reference, the platforms  66 ,  68  have been removed from  FIG. 9 . 
         [0065]    In this embodiment, the component  150  excludes the second flange (see second flange  58  of  FIGS. 2-6 ). The first flange  56 , the first platform  66 , the shell  52  and the spar  54  are substantially similar to the embodiment of  FIGS. 2-6 . However, a second shaft  99  may extend from the spar  54  at an opposite end from the shaft  84 . The second shaft  99  is received through an opening  101  of the second platform  68  (see  FIGS. 7 and 8 ). The spar  54  may pivot about the shafts  84 ,  99  to change a rotational positioning of the shell  52 . 
         [0066]      FIGS. 10A and 10B  illustrate yet another embodiment of a component  250  that can be incorporated into a gas turbine engine. For ease of reference, the platforms have been removed from  FIG. 10B . 
         [0067]    The first flange  56 , the first platform  66 , and the shell  52  are substantially similar to the embodiment of  FIGS. 2-6 . However, in this embodiment, the component  250  includes a second flange  258  received relative to a second platform  268 . The second flange  258  includes a post  105  that may extend through the second platform  268  and into a recess  107  defined by the spar  254 . The spar  254  may pivot via the shaft  84  and the post  105  to change a rotational positioning of the shell  52 . 
         [0068]    An opposite configuration is also contemplated in which the second flange  258  includes the recess  107  and the spar  254  includes the post  105  received within the recess  107 . The post  105  may embody any shape, including but not limited to round, hexagonal, square or rectangular. 
         [0069]    Although the different non-limiting embodiments are illustrated as having specific components, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0070]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure. 
         [0071]    The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.