Abstract:
An airfoil for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, an airfoil body and a cooling circuit disposed inside the airfoil body and including a leading edge cavity with a first portion extending from a radially inner wall to a radially outer wall of the airfoil body and a second portion that extends from a leading edge inner wall to a trailing edge inner wall of the airfoil body. The cooling circuit is configured to communicate cooling airflow through the first portion and the second portion prior to exiting the leading edge cavity into a second cavity of the cooling circuit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/326,720, filed Dec. 15, 2011. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates to a gas turbine engine, and more particularly to an airfoil cooling circuit for cooling an airfoil of a gas turbine engine. 
         [0003]    Gas turbine engines typically include a compressor section, a combustor section and a turbine section. In general, during operation, air is pressurized in the compressor section and 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 of the gas turbine engine typically include alternating rows of rotating blades and stationary vanes. The rotating blades extract the energy from the hot combustion gases that are communicated through the gas turbine engine, and the vanes convert the velocity of the airflow into pressure and prepare the airflow for the next set of blades. The hot combustion gases are communicated over airfoil bodies of the blades and vanes. The airfoil bodies can include cooling circuits that receive cooling airflow for cooling the airfoils during engine operation. 
       SUMMARY 
       [0005]    An airfoil for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, an airfoil body and a cooling circuit disposed inside the airfoil body and including a leading edge cavity with a first portion extending from a radially inner wall to a radially outer wall of the airfoil body and a second portion that extends from a leading edge inner wall to a trailing edge inner wall of the airfoil body. The cooling circuit is configured to communicate cooling airflow through the first portion and the second portion prior to exiting the leading edge cavity into a second cavity of the cooling circuit. 
         [0006]    In a further non-limiting embodiment of the foregoing airfoil, the second portion includes an oxbow shaped portion that transitions the leading edge cavity into the second cavity. 
         [0007]    In a further non-limiting embodiment of either of the foregoing airfoils, the airfoil is a vane. 
         [0008]    In a further non-limiting embodiment of any of the foregoing airfoils, a rib extends between the leading edge cavity and the second cavity. 
         [0009]    In a further non-limiting embodiment of any of the foregoing airfoils, the rib includes a plurality of openings that extend through the rib between the leading edge cavity and the second cavity. 
         [0010]    In a further non-limiting embodiment of any of the foregoing airfoils, the plurality of openings include increasing sizes in a direction extending from the radially inner wall toward the radially outer wall. 
         [0011]    In a further non-limiting embodiment of any of the foregoing airfoils, the rib is L-shaped. 
         [0012]    In a further non-limiting embodiment of any of the foregoing airfoils, a third cavity is in fluid communication with the second cavity. The third cavity includes a close-ended portion. 
         [0013]    In a further non-limiting embodiment of any of the foregoing airfoils, the third cavity extends across a length that is smaller than a length of a trailing edge of the airfoil body. 
         [0014]    In a further non-limiting embodiment of any of the foregoing airfoils, the closed-ended portion is disposed adjacent to an L-shaped portion of a rib. 
         [0015]    An airfoil for a gas turbine engine according to another exemplary aspect of the present disclosure includes, among other things, an airfoil body having a trailing edge that establishes a first length and a serpentine cooling circuit within the airfoil body and having a trailing edge cavity adjacent to the trailing edge that is in fluid communication with at least one other cavity of the serpentine cooling circuit. The trailing edge cavity extends across a second length of the airfoil body that is less than the first length and includes a close-ended portion. 
         [0016]    In a further non-limiting embodiment of the foregoing airfoil, the closed-ended portion is disposed adjacent to an L-shaped portion of a rib. 
         [0017]    In a further non-limiting embodiment of either of the foregoing airfoils, the rib separates the trailing edge cavity from the at least one other cavity. 
         [0018]    In a further non-limiting embodiment of any of the foregoing airfoils, the rib includes a plurality of openings that extend through the rib between trailing edge cavity and the at least one other cavity. 
         [0019]    In a further non-limiting embodiment of any of the foregoing airfoils, the serpentine cooling circuit includes a leading edge cavity with a first portion extending from a radially inner wall to a radially outer wall of the airfoil body and a second portion that extends from a leading edge inner wall to a trailing edge inner wall of the airfoil body. 
         [0020]    In a further non-limiting embodiment of any of the foregoing airfoils, the second portion includes an oxbow shaped portion that transitions the leading edge cavity into another cavity. 
         [0021]    In a further non-limiting embodiment of any of the foregoing airfoils, the serpentine cooling circuit is configured to communicate cooling airflow through the first portion and the second portion prior to exiting the leading edge cavity into a second cavity. 
         [0022]    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 
         [0023]      FIG. 1  schematically illustrates a gas turbine engine. 
           [0024]      FIG. 2  illustrates an airfoil of a gas turbine engine. 
           [0025]      FIG. 3  illustrates a cooling circuit that can be incorporated into the airfoil of  FIG. 2 . 
           [0026]      FIG. 4  illustrates another cooling circuit of an airfoil. 
           [0027]      FIG. 5  illustrates yet another cooling circuit of an airfoil. 
           [0028]      FIG. 6  illustrates another airfoil of a gas turbine engine. 
           [0029]      FIG. 7  illustrates a cooling circuit that can be incorporated into the airfoil of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  schematically illustrates a gas turbine engine  10 . The example gas turbine engine  10  is a two spool turbofan engine that generally incorporates a fan section  14 , a compressor section  16 , a combustor section  18  and a turbine section  20 . Alternative engines might include fewer or additional sections such as an augmenter section (not shown), among other systems or features. Generally, the fan section  14  drives air along a bypass flow path, while the compressor section  16  drives air along a core flow path for compression and communication into the combustor section  18 . The hot combustion gases generated in the combustor section  18  are expanded through the turbine section  20 . 
         [0031]    This view is highly schematic and is included to provide a basic understanding of the gas turbine engine  10  and not to limit the disclosure. This disclosure extends to all types of gas turbine engines and to all types of applications, including but not limited to, three spool turbofan configurations as well as land based gas turbine engines that do not necessarily incorporate a fan section. 
         [0032]    The example gas turbine engine  10  of  FIG. 1  generally includes at least a low speed spool  22  and a high speed spool  24  mounted for rotation about an engine centerline axis  12  relative to an engine static structure  27  via several bearing systems  29 . The low speed spool  22  generally includes an inner shaft  31  that interconnects a fan  33 , a low pressure compressor  17 , and a low pressure turbine  21 . The inner shaft  31  can connect to the fan  33  through a geared architecture  35  to drive the fan  33  at a lower speed than the low speed spool  22 . Although the geared architecture  35  is schematically depicted between the fan  33  and the low pressure compressor  17 , it should be understood that the geared architecture  35  could be disposed at other locations of the gas turbine engine  10 . The high speed spool  24  includes an outer shaft  37  that interconnects a high pressure compressor  19  and a high pressure turbine  23 . 
         [0033]    A combustor  15  is arranged between the high pressure compressor  19  and the high pressure turbine  23 . The inner shaft  31  and the outer shaft  37  are concentric and rotate about the engine centerline axis  12 . A core airflow is compressed by the low pressure compressor  17  and the high pressure compressor  19 , is mixed with fuel and burned within the combustor  15 , and is then expanded over the high pressure turbine  23  and the low pressure turbine  21 . The turbines  21 ,  23  rotationally drive the low speed spool  22  and the high speed spool  24  in response to the expansion. 
         [0034]    The compressor section  16  and the turbine section  20  can each include alternating rows of rotor assemblies  39  and vane assemblies  41 . The rotor assemblies  39  carry a plurality of rotating blades, while each vane assembly  41  includes a plurality of vanes. The blades of the rotor assemblies  39  create or extract energy (in the form of pressure) from core airflow that is communicated through the gas turbine engine  10 . The vanes of the vane assemblies  41  direct airflow to the blades of the rotor assemblies  39  to either add or extract energy. 
         [0035]    Various components of the gas turbine engine  10 , including airfoils such as the blades and vanes of the compressor section  16  and the turbine section  20 , are subjected to repetitive thermal cycling under widely ranging temperatures and pressures. The hardware of the turbine section  20  is subjected to particularly extreme operating conditions. Therefore, some components may require internal cooling circuits for cooling the parts during engine operation. Example cooling circuits for cooling components are discussed below. 
         [0036]      FIG. 2  illustrates an airfoil  40  that can be incorporated into a gas turbine engine, such as the gas turbine engine  10  of  FIG. 1 . In this example, the airfoil  40  is a vane of a vane assembly  41  of either the turbine section  20  or the compressor section  16 . However, the teachings of this disclosure are not limited to vane airfoils and could extend to other airfoils including blades and also non-airfoil hardware of the gas turbine engine. This disclosure also could extend to airfoils of a middle turbine frame of the gas turbine engine  10 . 
         [0037]    The airfoil  40  includes an airfoil body  42  that extends between an inner platform  44  (on an inner diameter side) and an outer platform  46  (on an outer diameter side). The airfoil  40  also includes a leading edge  48 , a trailing edge  50 , a pressure side  52  and a suction side  54 . The airfoil body  42  extends in chord between the leading edge  48  and the trailing edge  50 . 
         [0038]    Both the inner platform  44  and the outer platform  46  include leading and trailing edge rails  56  having one or more engagement features  57  for mounting the airfoil  40  to the gas turbine engine  10 , such as to an engine casing. Other engagement feature configurations are contemplated as within the scope of this disclosure, including but not limited to, hooks, rails, bolts, rivets and tabs that can be incorporated into the airfoil  40  to retain the airfoil  40  to the gas turbine engine  10 . 
         [0039]    A gas path  58  is communicated axially downstream through the gas turbine engine  10  in a direction that extends from the leading edge  48  toward the trailing edge  50  of the airfoil body  42 . The gas path  58  (for the communication of core airflow along a core flow path) extends between an inner gas path  60  associated with the inner platform  44  and an outer gas path  62  associated with the outer platform  46  of the airfoil  40 . The inner platform  44  and the outer platform  46  are connected to the inner and outer gas paths  60 ,  62  via fillets  64 . 
         [0040]    The airfoil body  42  includes an internal core  66  having an inlet  68  that receives a cooling airflow  70  from an airflow source  75  that is external to the airfoil  40 . In this embodiment, the inlet  68  of the internal core  66  is positioned at the outer platform  46  of the airfoil  40 , although the inlet  68  could also be positioned at the inner platform  44 . The cooling airflow  70  is a lower temperature than the airflow of the gas path  58  that is communicated across the airfoil body  42 . In one example, the cooling airflow  70  is a bleed airflow that can be sourced from the compressor section  16  or any other portion of the gas turbine engine  10  that is upstream from the airfoil  40 . The cooling airflow  70  is circulated through a cooling circuit  72  (See  FIGS. 3-5 ) of the airfoil  40  to transfer thermal energy from the airfoil  40  to the cooling airflow  70 . 
         [0041]    A cooling circuit such as disclosed herein can be disposed in any component that requires cooling, including but not limited to those components that are exposed to the gas path  58  of the gas turbine engine  10 . In the illustrated embodiments and for the purpose of providing detailed examples, the cooling circuits of this disclosure are disposed within a portion of an airfoil, such as a stator vane ( FIGS. 2-5 ) or a rotor blade ( FIGS. 6-7 ). It should be understood, however, that the cooling circuits are not limited to these applications and can be utilized within other areas of the gas turbine engine that are exposed to relatively extreme environments. 
         [0042]      FIG. 3  illustrates an example cooling circuit  72  of an airfoil  40 . The cooling circuit  72  is defined inside of the airfoil body  42 . In this example, the cooling circuit  72  establishes a multi-pass cooling passage within the internal core  66  of the airfoil body  42 . Although a three-pass cooling circuit is depicted by  FIG. 3 , it should be understood that the cooling circuit  72  could include any number of passes. For example, a two-pass or four-pass cooling passage could be incorporated into the airfoil  40 . 
         [0043]    The example cooling circuit  72  includes a first cavity  74  (i.e., a leading edge cavity), a second cavity  76  (i.e., an intermediate cavity), and a third cavity  78  (i.e., a trailing edge cavity). The cavities  74 ,  76 ,  78  direct the cooling airflow  70  through the cooling circuit  72  to cool any high temperature areas of the airfoil body  42 . The first cavity  74  is in fluid communication with the second cavity  76 , and the second cavity  76  is in fluid communication with the third cavity  78 . Accordingly, the cooling airflow  70  received within the cooling circuit  72  can be circulated through the first cavity  74 , then through the second cavity  76 , and then through the third cavity  78  to cool the airfoil  40 . 
         [0044]    A first rib  80  separates the first cavity  74  from the second cavity  76 , and a second rib  82  divides the second cavity  76  from the third cavity  78 . In this example, the first rib  80  and the second rib  82  are generally L shaped. The first and second ribs  80 ,  82  extend generally parallel to a longitudinal axis of the airfoil  40 . In this example, the first rib  80  extends across a greater radial depth than the second rib  82  (i.e., the first rib  80  is longer than the second rib  82 ). 
         [0045]    The internal core  66  of the airfoil  40  establishes a leading edge inner wall  67 , a trailing edge inner wall  69 , an inner platform inner wall  71  and an outer platform inner wall  73 . The cooling circuit  72  extends axially between the leading edge inner wall  67  and the trailing edge inner wall  69  and radially between the inner platform inner wall  71  and the outer platform inner wall  73 . 
         [0046]    The first cavity  74  of the cooling circuit  72  includes a first portion  84  and a second portion  86  that is transverse relative to the first portion  84 . In one example, the second portion  86  is generally perpendicular relative to the first portion  84  and establishes a turn  87  at the inner platform inner wall  71 . The first portion  84  extends in span between the inner platform inner wall  71  and the outer platform inner wall  73  of the airfoil body  42 . The second portion  86  extends in chord between the leading edge  48  and the trailing edge  50  of the airfoil body  42 . In one example, the second portion  86  extends across an entire space  89  between the leading edge inner wall  67  and the trailing edge inner wall  69 . In other words, the first cavity  74  can extend across the entire radial length and axial width of the internal core  66 . The second portion  86  can include a U-shape curved portion  88  (i.e., an oxbow shaped portion) that transitions the first cavity  74  into the second cavity  76 . 
         [0047]    The cooling airflow  70  can be communicated between the outer platform  46  and the inner platform  44  within the first portion  84  of the first cavity  74 , and then from the leading edge  48  to the trailing edge  50  of the airfoil body  42  within the second portion  86  of the first cavity  74  before being communicated into the second cavity  76  of the cooling circuit  72 . After the cooling airflow  70  is circulated back toward the outer platform inner wall  73 , the cooling airflow  70  can be circulated into the third cavity  78 . It should be understood that an opposite configuration is also contemplated in which the cooling airflow  70  is communicated from the trailing edge  50  toward the leading edge  48 , or from the inner platform  44  toward the outer platform  46 , or both. 
         [0048]    Once in the third cavity  78 , the cooling airflow  70  is communicated radially across a length L 2  that is only a portion of a length L 1  of the trailing edge  50  of the airfoil body  42  and can be communicated to the gas path  58 . In one example, the length L 2  is 75% of the length of L 1 . In another example, the length L 2  is between 50% and 85% of the length L 1 . The actual length L 2  of the third cavity  78  can vary depending on the size and shape of the airfoil body  42 . 
         [0049]    The third cavity  78  includes a close-ended portion  79  that is established by an L-shaped portion  83  of the second rib  82 . In other words, the third cavity  78  does not extend all the way to the inner platform  44  of the airfoil  40 . The cooling circuit  72  communicates the cooling airflow  70  through the airfoil body  42  without the need to extract the cooling airflow  70  from the lower portion of the airfoil body  42  after it is circulated through the third cavity  78 . 
         [0050]    The gas path  58  defines a temperature profile that may be peeked near the outer gas path  62  of the airfoil  40 . In other words, during engine operation, the airfoil  40  is hottest near the outer gas path  62  and coolest near the inner gas path  60  (or vice versa). The cooling circuit  172  described above is designed to address the cooling requirements necessitated by such temperature profiled while avoiding dead spots (i.e., areas within the internal core  66  where the cooling airflow  70  does not actively move) without wasting cooling airflow  70 . 
         [0051]      FIG. 4  illustrates another example cooling circuit  172  of the airfoil  40 . The cooling circuit  172  is substantially similar to the cooling circuit  72  of  FIG. 3  except that the cooling circuit  172  includes additional features that can be incorporated into the internal core  66  of the airfoil  40 . For example, a rib  182  of the second cooling circuit  172  that is adjacent to the trailing edge  50  includes a plurality of openings  92  that extend through the rib  182  between a second cavity  176  and a third cavity  178 . The openings  92  can include increasing sizes S 1  to Sn in a direction that extends from the inner diameter of the airfoil  40  toward the outer diameter of the airfoil  40 . The actual number, size, geometry, and overall configuration of the openings  92  can vary and is not intended to limit this disclosure. 
         [0052]    The openings  92  allow the cooling airflow  70  to be communicated from the second cavity  176  into the third cavity  178  prior to circulating the cooling airflow  70  through an entire length of the second cavity  176  (i.e. all the way to the outer platform inner wall  73  of this example). The cooling circuit  172  can also include a second plurality of openings  94  through which the cooling airflow  70  can escape the third cavity  178 . In this example, the openings  94  are positioned near the trailing edge  50  of the airfoil  40 . The openings  94  can be drilled into the airfoil body  42  or can be formed in another know manner. The trailing edge  50  can include an increasing number of openings  94  toward the outer platform  46  of the airfoil  40 . 
         [0053]      FIG. 5  illustrates yet another cooling circuit  272  of the airfoil  40 . The cooling circuit  272  is substantially similar to the cooling circuits  72 ,  172  expect that the cooling circuit  272  includes a plurality of teardrop shaped holes  96  in addition to or in place of the second plurality of openings  94 . The teardrop shaped holes  96  can provide additional cooling capacity for the cooling circuit  272 . The teardrop shaped holes  96  are positioned radially outboard of the inner gas path  60 . The teardrop shaped holes  96  can be formed using a ceramic core or a refractory metal core or in other known manners. 
         [0054]      FIG. 6  illustrates another airfoil  340  that can be incorporated into the gas turbine engine  10 . In this example, the airfoil  340  is a blade, such as a blade of a rotor assembly. The airfoil  340  can be incorporated into either the compressor section  16  or the turbine section  20  of the gas turbine engine  10 . 
         [0055]    The airfoil  340  includes an airfoil body  342  that extends between a tip portion  98  and a root portion  99 . The root portion  99  can include a fir-tree configuration  101  for attachment to a rotor assembly (not shown) for circumferential rotation about the engine centerline axis  12 . Of course, other attachment configurations are also contemplated. 
         [0056]    The airfoil body  342  extends between a leading edge  103  and a trailing edge  105  and includes a suction side  107  and a pressure side  109 . The root portion  99  can also include a platform  111 . A gas path  58  is communicated axially downstream through the gas turbine engine  10  in a direction that extends from the leading edge  103  toward the trailing edge  105  of the airfoil body  342 . The gas path  58  (for the communication of core airflow along a core flow path) extends between an inner gas path  360  associated with the platform  111  and an outer gas path  362  associated with the tip portion  98  of the airfoil  340 . 
         [0057]    The airfoil body  342  includes an internal core  366  (See  FIG. 7 ) having an inlet  368  that receives a cooling airflow  370  from an airflow source  375  that is external to the airfoil  340 . In this embodiment, the inlet  368  of the internal core  366  is positioned on the radially inward side of the airfoil  340  (i.e., adjacent to the root portion  99 ). The cooling airflow  370  is a lower temperature than the airflow of the gas path  58  that is communicated across the airfoil body  342 . The cooling airflow  370  can be sourced from the compressor section  16  or any other portion of the gas turbine engine  10  that is upstream from the airfoil  340 . The cooling airflow  370  is circulated through a cooling circuit  372  (See  FIG. 7 ) of the airfoil  340  to transfer thermal energy from the airfoil  340  to the cooling airflow  370 . 
         [0058]      FIG. 7  illustrates an example cooling circuit  372  of the airfoil  340 . The cooling circuit  372  is defined inside of the airfoil body  342 . The cooling circuit  372  establishes a multi-pass cooling passage within the internal core  366  of the airfoil body  342 . The inlet  368  of the cooling circuit  372  is partitioned to include a multitude of openings  369  that receive the cooling airflow  370  from the airflow source  375 . 
         [0059]    The cooling circuit  372  includes a first cavity  374  (i.e., a leading edge cavity), a second cavity  376  (i.e., an intermediate cavity), and a third cavity  378  (i.e., a trailing edge cavity). The cavities  374 ,  376 ,  378  direct the cooling airflow  370  through the cooling circuit  372  to cool any high temperature areas of the airfoil  340 . The first cavity  374  is in fluid communication with the second cavity  376 , and the second cavity  376  is in fluid communication with the third cavity  378 . Accordingly, the cooling airflow  370  received within the cooling circuit  372  can be circulated through the first cavity  374 , then through the second cavity  376 , and then through the third cavity  378  to cool the airfoil  340 . 
         [0060]    A first rib  380  separates the first cavity  374  from the second cavity  376 , and a second rib  382  divides the second cavity  376  from the third cavity  378 . In this example, the first rib  380  and the second rib  382  are generally L shaped. The first and second ribs  380 ,  382  extend generally parallel to a longitudinal axis of the airfoil  340 . The first rib  380  can extend across a greater radial depth than the second rib  382  (i.e., the first rib  380  is longer than the second rib  382 ). 
         [0061]    The internal core  366  of the airfoil  340  establishes a leading edge inner wall  367 , a trailing edge inner wall  369 , a radially inner wall  371  and a radially outer wall  373 . The cooling circuit  372  extends axially between the leading edge inner wall  367  and the trailing edge inner wall  369  and radially between the radially inner wall  371  and the radially outer wall  373 . 
         [0062]    The first cavity  374  of the cooling circuit  372  includes a first portion  384  and a second portion  386  that is transverse to the first portion  384 . In one example, the second portion  386  is generally perpendicular relative to the first portion  384  and establishes a turn  387  at the radially outer wall  373 . The first portion  384  extends in span between an inner diameter  351  and an outer diameter  353  of the airfoil  340 . The second portion  386  extends in chord between the leading edge  103  and the trailing edge  105  of the airfoil body  342 . The second portion  386  can extend across an entire space  389  between the leading edge inner wall  367  and the trailing edge inner wall  369 . In other words, the first cavity  374  can extend across the entire radial length and axial width of the internal core  366 . The second portion  386  can include a U-shape curved portion  388  that transitions the first cavity  374  into the second cavity  376 . 
         [0063]    The cooling airflow  370  can be communicated between the root portion  99  and the tip portion  98  within the first portion  384  of the first cavity  374 , and then from the leading edge  103  to the trailing edge  105  of the airfoil body  342  within the second portion  386  of the first cavity  374  before being communicated into the second cavity  376  of the cooling circuit  372 . After the cooling airflow  370  is circulated back toward the radially inner wall  373 , the cooling airflow  370  can be circulated into the third cavity  378 . It should be understood that an opposite configuration is also contemplated in which the cooling airflow  370  is communicated from the trailing edge  105  toward the leading edge  103 , or from the tip portion  98  toward the root portion  99 , or both. 
         [0064]    Once in the third cavity  378 , the cooling airflow  370  is communicated radially across a length L 2  that is only a portion of a length L 1  of the trailing edge  105  of the airfoil body  342 . In one example, the length L 2  is 75% of the length of L 1 . In another example, the length L 2  is between 50% and 85% of the length L 1 . The actual length L 2  of the third cavity  378  can vary depending on the size and shape of the airfoil body  342 . 
         [0065]    The third cavity  378  includes a close-ended portion  379  that is established by an L-shaped portion  383  of the second rib  382 . In other words, the third cavity  378  does not extend across the entire length L 1  of the trailing edge  105 . The cooling circuit  372  communicates the cooling airflow  370  through the airfoil body  342  without the need to extract the cooling airflow  370  from the tip portion  98  of the airfoil body  342  after it is circulated through the third cavity  378 . 
         [0066]    The gas path  58  may define a temperature profile that is peeked near the inner gas path  360  of the airfoil  340 . In other words, during engine operation, the airfoil  340  is hottest near the inner gas path  360  and coolest near the outer gas path  362  (or vice versa). The cooling circuit  372  described above is designed to address the cooling requirements necessitated by such a temperature profile while avoiding dead spots (i.e., areas within the internal core  366  where the cooling airflow  370  does not actively move) without wasting cooling airflow  370 . 
         [0067]    The cooling circuit  372  can also incorporate additional features including those features shown in  FIGS. 5-6  related to the cooling circuits  172 ,  272 . For example, the openings  92 ,  94 , and  96  can be incorporated into the cooling circuit  372 . 
         [0068]    Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
         [0069]    Furthermore, 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.