Abstract:
One embodiment of the present invention is a unique method of manufacturing a component for a turbomachine, such as an airfoil. Another embodiment is a unique airfoil. Yet another embodiment is a unique gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for cooled gas turbine engine components. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims benefit of U.S. Provisional Patent Application No. 61/581,844 filed Dec. 30, 2011, entitled AIRFOIL, METHOD OF MANUFACTURING AN AIRFOIL, AND GAS TURBINE ENGINE, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to gas turbine engines, and more particularly, to airfoils and other cooled components for gas turbine engines. 
       BACKGROUND 
       [0003]    Cooled gas turbine engine components that are cooled by cooling fluids, such as a gas turbine engine airfoil cooled by cooling air, remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
       SUMMARY 
       [0004]    One embodiment of the present invention is a unique method of manufacturing a component for a turbomachine, such as an airfoil. Another embodiment is a unique airfoil. Yet another embodiment is a unique gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for cooled gas turbine engine components. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0006]      FIG. 1  schematically illustrates some aspects of a non-limiting example of a gas turbine engine in accordance with an embodiment of the present invention. 
           [0007]      FIG. 2  depicts some aspects of a non-limiting example of an airfoil having a composite foam cooling passage in accordance with an embodiment of the present invention. 
           [0008]      FIG. 3  depicts some aspects of a non-limiting example of a top view of the airfoil of  FIG. 2  in accordance with an embodiment of the present invention 
           [0009]      FIGS. 4 and 5  depict some aspects of a non-limiting example of an airfoil having a composite foam cooling passage in accordance with an embodiment of the present invention. 
           [0010]      FIG. 6  depicts some aspects of a non-limiting example of an airfoil having a metallic spar in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain embodiments of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
         [0012]    Referring to the drawings, and in particular  FIG. 1 , there are illustrated some aspects of a non-limiting example of a gas turbine engine  20  in accordance with an embodiment of the present invention. In one form, engine  20  is a propulsion engine, e.g., an aircraft propulsion engine. In other embodiments, engine  20  may be any other type of gas turbine engine, e.g., a marine gas turbine engine, an industrial gas turbine engine, or any aero, aero-derivative or non-aero gas turbine engine. In one form, engine  20  is a two spool engine having a high pressure (HP) spool  24  and a low pressure (LP) spool  26 . In other embodiments, engine  20  may include only a single spool, or may include three or more spools, e.g., may include an intermediate pressure (IP) spool and/or other spools. In one form, engine  20  is a turbofan engine. In other embodiments, engine  20  may be any other type of gas turbine engine, such as a turboprop engine, a turboshaft engine, a propfan engine, a turbojet engine or a hybrid engine. As a turbofan engine, LP spool  26  is coupled to and operative to drive a propulsor  28  in the form of a turbofan (fan) system, which may be referred to as a turbofan, a fan or a fan system. As a turboprop engine, LP spool  26  powers a propulsor  28  in the form of a propeller system (not shown), e.g., via a reduction gearbox (not shown). As a propfan engine, LP spool  26  powers a propulsor  28  in the form of a propfan. In other embodiments, propulsor  28  may take other forms, such as one or more helicopter rotors or tilt-wing aircraft rotors, for example, powered by one or more engines  20  in the form of one or more turboshaft engines. 
         [0013]    In one form, engine  20  includes, in addition to fan  28 , a bypass duct  30 , a compressor  32 , a diffuser  34 , a combustor  36 , a high pressure (HP) turbine  38 , a low pressure (LP) turbine  40 , a nozzle  42 A, a nozzle  42 B, and a tailcone  46 , which are generally disposed about and/or rotate about an engine centerline  49 . In other embodiments, there may be, for example, an intermediate pressure spool having an intermediate pressure turbine. In one form, engine centerline  49  is the axis of rotation of fan  28 , compressor  32 , turbine  38  and turbine  40 . In other embodiments, one or more of fan  28 , compressor  32 , turbine  38  and turbine  40  may rotate about a different axis of rotation. 
         [0014]    In the depicted embodiment, engine  20  core flow is discharged through nozzle  42 A, and the bypass flow is discharged through nozzle  42 B. In other embodiments, other nozzle arrangements may be employed, e.g., a common nozzle for core and bypass flow; a nozzle for core flow, but no nozzle for bypass flow; or another nozzle arrangement. Bypass duct  30  and compressor  32  are in fluid communication with fan  28 . Nozzle  42 B is in fluid communication with bypass duct  30 . Diffuser  34  is in fluid communication with compressor  32 . Combustor  36  is fluidly disposed between compressor  32  and turbine  38 . Turbine  40  is fluidly disposed between turbine  38  and nozzle  42 A. In one form, combustor  36  includes a combustion liner (not shown) that contains a continuous combustion process. In other embodiments, combustor  36  may take other forms, and may be, for example, a wave rotor combustion system, a rotary valve combustion system, a pulse detonation combustion system, a continuous detonation combustion system or a slinger combustion system, and may employ deflagration and/or detonation combustion processes. 
         [0015]    Fan system  28  includes a fan rotor system  48  driven by LP spool  26 . In various embodiments, fan rotor system  48  may include one or more rotors (not shown) that are powered by turbine  40 . In various embodiments, fan  28  may include one or more fan vane stages (not shown in  FIG. 1 ) that cooperate with fan blades (not shown) of fan rotor system  48  to compress air and to generate a thrust-producing flow. Bypass duct  30  is operative to transmit a bypass flow generated by fan  28  around the core of engine  20 . Compressor  32  includes a compressor rotor system  50 . In various embodiments, compressor rotor system  50  includes one or more rotors (not shown) that are powered by turbine  38 . Compressor  32  also includes a plurality of compressor vane stages (not shown in  FIG. 1 ) that cooperate with compressor blades (not shown) of compressor rotor system  50  to compress air. In various embodiments, the compressor vane stages may include a compressor discharge vane stage and/or one or more diffuser vane stages. 
         [0016]    Turbine  38  includes a turbine rotor system  52 . In various embodiments, turbine rotor system  52  includes one or more rotors (not shown) coupled to and operative to drive compressor rotor system  50 . Turbine  38  also includes a plurality of turbine vane stages (not shown in  FIG. 1 ) that cooperate with turbine blades (not shown) of turbine rotor system  52  to extract power from the hot gases discharged by combustor  36 . Turbine rotor system  52  is drivingly coupled to compressor rotor system  50  via a shafting system  54 . Turbine  40  includes a turbine rotor system  56 . In various embodiments, turbine rotor system  56  includes one or more rotors (not shown) coupled to and operative to drive fan rotor system  48 . Turbine  40  also includes a plurality of turbine vane stages (not shown in  FIG. 1 ) that cooperate with turbine blades (not shown) of turbine rotor system  56  to extract power from the hot gases discharged by turbine  38 . Turbine rotor system  56  is drivingly coupled to fan rotor system  48  via a shafting system  58 . In various embodiments, shafting systems  54  and  58  include a plurality of shafts that may rotate at the same or different speeds and directions for driving fan rotor system  48  rotor(s) and compressor rotor system  50  rotor(s). In some embodiments, only a single shaft may be employed in one or both of shafting systems  54  and  58 . Turbine  40  is operative to discharge the engine  20  core flow to nozzle  42 A. 
         [0017]    During normal operation of gas turbine engine  20 , air is drawn into the inlet of fan  28  and pressurized by fan rotor  48 . Some of the air pressurized by fan rotor  48  is directed into compressor  32  as core flow, and some of the pressurized air is directed into bypass duct  30  as bypass flow. Compressor  32  further pressurizes the portion of the air received therein from fan  28 , which is then discharged into diffuser  34 . Diffuser  34  reduces the velocity of the pressurized air, and directs the diffused core airflow into combustor  36 . Fuel is mixed with the pressurized air in combustor  36 , which is then combusted. The hot gases exiting combustor  36  are directed into turbines  38  and  40 , which extract energy in the form of mechanical shaft power to drive compressor  32  and fan  28  via respective shafting systems  54  and  58 . The hot gases exiting turbine  40  are discharged through nozzle system  42 A, and provide a component of the thrust output by engine  20 . 
         [0018]    Gas turbine engine  20  employs many airfoils in the form of blades and vanes in order to pressurize, expand and/or direct the flow of air and/or combustion products in and through engine  20 . The airfoils are used in fan  28 , compressor  32  and turbines  38  and  40 . Some of the airfoils operate at high temperatures, for which cooling may be desired, e.g., the latter vane and/or blade stages of compressor  32  and some or all stages of turbines  38  and  40  e.g., depending on the particular application and operating temperatures associated therewith. In addition, other gas turbine engine components operate at high temperatures, and may require cooling, for example but without limitation, flowpath wall structures, struts and other stationary or rotating components. It is desirable that the airfoils and other components be light in weight, e.g., in order to reduce the weight of gas turbine engine  20 . Accordingly, embodiments of the present invention envision, among other things, airfoils and other components formed entirely or partially of a composite material and having one or more composite foam cooling passages. By using composite foam cooling passages, structural integrity of the airfoil is increased, e.g., relative to cooling passages that are devoid of structure, since the composite foam has load bearing capacity, and high surface area for heat transfer from the airfoil to the cooling fluid. The term, “composite foam,” as used herein, relates to foams, e.g., open cell foams, formed of one or more composite materials, monolithic ceramic (for example and without limitation, SiC and/or SiN), a heterogeneous ceramic, or other nonmetallic materials. Although embodiments are described herein as with respect to airfoils for gas turbine engines, the present application also envisions embodiments pertaining to airfoils for other types of turbomachinery, as well as other types of cooled components for any type of machinery or equipment in addition to gas turbine engines. 
         [0019]    Referring to  FIG. 2 , some aspects of a non-limiting example of a component  60  in accordance with an embodiment of the present invention are depicted. In one form, component  60  is an airfoil, referred to herein as airfoil  60 . In other embodiments, component  60  may be one or more of any other turbomachine or engine  20  component types. For example, component  60  may be any component utilized in compressor  32 , combustor  36 , HP turbine  38 , LP turbine  40  and/or any other section or portion of gas turbine engine  20 . In various embodiments, component  60  may be, for example and without limitation, a bladetrack, a seal segment, a combustor liner, a vane endwall, a platform, a shroud, a strut and/or any other gas turbine engine component, e.g., which might require cooling during the operation of engine  20 . 
         [0020]    In one form, airfoil  60  includes an external portion  62  and an internal portion  64 , the latter of which is only generically depicted in  FIG. 2 . In various embodiments, internal portion  64  may extend entirely or partially through external portion  62  in a spanwise direction  66 . In one form, external portion  62  is formed of a composite material. In other embodiments, external portion  62  may be formed of a monolithic material. In one form, external portion  62  is a ceramic matrix composite (CMC). In other embodiments, external portion  62  may be one or more of another type of composite material in addition to or in place of CMC, for example and without limitation, a functionally graded ceramic or an organic matrix composite (OMC). In one form, external portion  62  is formed by enveloping internal portion  64  with a plurality of composite wrap plies  68  to form an airfoil body  70  into a desired shape, e.g., an airfoil shape, e.g., by wrapping composite wrap plies  68  around internal portion  64  and otherwise stacking composite wrap plies  68  in such a manner as to yield an airfoil shape around internal portion  64 . Removable core support pins are not employed to support internal portion  64 . Body  70  is then rigidized, e.g., fired in a suitable atmosphere, to form airfoil  60 . In various embodiments, internal portion  64  includes one or more composite portions that may be rigidized at the same time as external portion  62  and/or before rigidization of external portion  62 , e.g., one or more composite foam structures that form one or more composite foam cooling passages, as set forth below, and in some embodiments, one or more composite filler tape and/or composite filler fabric portions. 
         [0021]    Referring to  FIG. 3  in conjunction with  FIG. 2 , some aspects of a non-limiting example of internal portion  64  in accordance with an embodiment of the present invention are depicted. For the purpose of simplicity of illustration, external portion  62  is not depicted in  FIG. 3 . In various embodiments, internal portion  64  includes one or more composite foam structures. In the embodiment depicted in  FIG. 3 , internal portion  64  includes a single composite foam structure  72 . Other embodiments may include multiple composite foam structures  72 . In one form, internal portion  64  also includes a composite filler  74  surrounding the length of composite foam structure  72  in spanwise direction  66 . Removable core support pins are not employed to support composite foam structure  72 . In various embodiments, composite filler  74  may surround substantially all of or only part of composite foam structure  72 . For example, in some embodiments, part of composite foam structure  72  may be in direct contact with external portion  64 . In other embodiments, internal portion  64  may not employ a composite filler, such as composite filler  74 . 
         [0022]    Composite foam structure  72  forms a composite foam cooling passage, and is configured to pass a cooling fluid therethrough, e.g., air. In one form, composite foam structure  72  is a CMC foam. In other embodiments, composite foam structure  72  may be one or more of another type of composite material in addition to or in place of CMC, for example and without limitation, an OMC. Composite foam structure  72  is formed into a desired shape, i.e., the desired shape of all or a portion of a composite foam cooling passage. 
         [0023]    The shape of composite foam structure  72  may vary with the needs of the application, and includes simple shapes, e.g., an airfoil-like shape extending into internal portion  64 , as depicted in  FIG. 3 , to complex shapes, including, for example, serpentine shapes and/or other complex shapes, yielding cooling passages that direct cooling fluid in two or three dimensions. In one form, composite foam structure  72  is rigidized prior to the rigidization of external portion  62 . In other embodiments, composite foam structure  72  may be rigidized at the same time as external portion  62 . In one form, composite foam structure  72  extends all the way through external portion  62  in spanwise direction  66 . In other embodiments, composite foam structure  72  may extend only partially through external portion  62 . 
         [0024]    In one form, composite filler  74  is a ceramic tape. In some embodiments, ceramic fabric may be employed in addition to or in place of ceramic tape. In other embodiments, other types of composite filler may be employed. In one form, composite filler  74  is a CMC filler. In other embodiments, composite filler  74  may be one or more of another type of composite material in addition to or in place of CMC, for example and without limitation, an OMC. 
         [0025]    Composite filler  74  is applied and/or stacked onto composite foam structure  72 , e.g., about its entire periphery  76 . In some embodiments, the entire periphery  76  may not be surrounded by composite filler  74 . In one form, periphery  76  is surrounded by composite filler  74  along the entire length of composite foam structure  72  (which is approximately perpendicular to the plane of view of  FIG. 3 ) but does not close off the ends of composite foam structure  72 , thereby allowing cooling fluid to pass into, through and out of composite foam structure  72  from one end to the other. In some embodiments, composite filler  74  is also applied and/or stacked onto one or more ends of composite foam structure  72 , e.g., to limit or prevent the flow of cooling fluid into or out of one or both ends of the composite foam structure. In some embodiments, composite filler  74  may not be applied and/or stacked along the entire length of composite foam structure  72 . 
         [0026]    Referring to  FIGS. 4 and 5  in conjunction with  FIG. 2 , some aspects of another non-limiting example of internal portion  64  in accordance with an embodiment of the present invention are depicted. For the purpose of simplicity of illustration, external portion  62  is not depicted in  FIG. 4 . The view of  FIG. 4  is from the same perspective as that of  FIG. 3 . In the embodiment of  FIG. 4 , internal portion  64  includes a composite foam cooling passage  78 , a composite foam cooling passage  80  and composite filler  74 . Composite foam cooling passage  78  is depicted in  FIG. 5 , wherein composite filler  74  is not illustrated for clarity. Composite foam cooling passage  80  is similar to composite foam cooling passage  78 , and hence, the description of composite foam cooling passage  78  applies equally to composite foam cooling passage  80 . 
         [0027]    In one form, composite foam cooling passage  78  is a serpentine passage formed of three composite foam structures  72 A,  72 B and  72 C, each of which are formed into desired shapes and configured to pass cooling fluid therethrough. In other embodiments, composite foam cooling passage  78  may be a single unitary composite foam structure formed into the desired shape, e.g., the serpentine shape depicted in  FIG. 5 . In one form, composite filler  74  is applied and/or stacked along the entirety of composite foam cooling passage  78 , including the volume between composite foam structures  72 A,  72 B and  72 C, except at end faces  82  and  84  of composite foam cooling passage  78 , thus sealing the balance of composite foam cooling passage  78  and forming internal portion  64 . Cooling fluid may thus be directed to flow into either end face  82  or end face  84 , and will exit through the opposite end face  84  or end face  82 . For example, cooling air may be directed into end face  82 , and will flow through composite foam structure  72 A along its length  86 , through composite foam structure  72 B, which bridges between composite foam structures  72 A and  72 C, and through composite foam structure  72 C, after which the cooling air exits through end face  84 . 
         [0028]    In one form, the density of the composite foam structure is varied in order to generate one or more desired pressure drops at one or more desired locations in composite foam cooling passage  78 , e.g., one or more locations in one or more of composite foam structures  72 A,  72 B and  72 C. For example, assuming composite foam structure  72 A was disposed on the hot side of airfoil  60 , the density of composite foam structure  72 A may be increased at one or more desired locations along its length  86  (or the entirety of length  86 ) in order to generate an increased pressure drop and hence greater heat transfer to the cooling fluid at such locations (or along the entirety of length  86 ). 
         [0029]    Referring to  FIG. 6  in conjunction with  FIG. 2 , some aspects of another non-limiting example of internal portion  64  in accordance with an embodiment of the present invention are depicted. For the purpose of simplicity of illustration, external portion  62  is not depicted in  FIG. 6 . The view of  FIG. 6  is from the same perspective as that of  FIG. 3 . In the embodiment of  FIG. 6 , internal portion  64  includes a composite foam structure  88  disposed around a metallic spar  90 . Composite foam structure  88  and metallic spar  90  form internal portion  64 , and are surrounded by external portion  62 . In some embodiments, composite filler  74  may be disposed between composite foam structure  88  and external portion  62  and/or between composite foam structure  88  and metallic spar  90  and/or at other locations. In one form, metallic spar  90  is hollow, e.g., having an opening  92  disposed therein. Composite foam structure  88  forms a composite foam cooling passage that is effective for cooling metallic spar  90  and external portion  62 . 
         [0030]    It will be understood that many variations of composite cooling structures/passages may be employed to accommodate many variations in cooling schemes, for example and without limitation, including employing openings or composite cooling structures, e.g., extending from the composite cooling passages illustrated herein, that provide cooling air to different portions of airfoil  60 , e.g., for film cooling, impingement cooling or other cooling schemes. As an example, cooling air may be supplied to a trailing edge gill slot cooling scheme from a composite cooling passage in accordance with an embodiment of the present invention. 
         [0031]    Embodiments of the present invention include a method of manufacturing an a component for a turbomachine, comprising: forming an internal portion of the component, including forming a first composite foam structure to a desired shape, wherein the first composite foam structure is configured to pass a cooling fluid therethrough; enveloping the internal portion of the component with composite wrap plies to form a body, without using a removable core support pin to support the internal portion of the component; and rigidizing the body. 
         [0032]    In a refinement, the enveloping includes forming the body as an airfoil shape using the composite wrap plies. 
         [0033]    In another refinement, the method further comprises stacking one or both of a composite filler tape and a composite filler fabric onto the first composite foam structure to form the internal portion of the component, without using a removable core support pin to support the first composite foam structure. 
         [0034]    In yet another refinement, the stacking of the one or both of the composite filler tape and the composite filler fabric onto the first composite foam structure includes applying the one or both of the composite filler tape and the composite filler fabric along a length of the first composite foam structure. 
         [0035]    In still another refinement, the method further comprises: forming a second composite foam structure to a desired shape, wherein the second composite foam structure is configured to pass at least some the cooling fluid therethrough; and stacking the one or both of the composite filler tape and the composite filler fabric onto the second composite foam structure in addition to the first composite foam structure to form the internal portion of the component. 
         [0036]    In yet still another refinement, the stacking of the one or both of the composite filler tape and the composite filler fabric onto the second composite foam structure in addition to the first composite foam structure includes applying the one or both of the composite filler tape and the composite filler fabric along a length of the first composite foam structure and of the second composite foam structure. 
         [0037]    In a further refinement, the stacking of the one or both of the composite filler tape and the composite filler fabric onto the second composite foam structure in addition to the first composite foam structure includes applying the one or both of the composite filler tape and the composite filler fabric between the first composite foam structure and of the second composite foam structure. 
         [0038]    In a yet further refinement, the method further comprises: forming a third composite foam structure to a desired shape; wherein the second composite foam structure is configured to pass at least some of the cooling fluid therethrough; and wherein the third composite foam structure is configured to bridge between the first composite foam structure and the second composite foam structure and allow the at least some of the cooling fluid to flow between the first composite foam structure and the second composite foam structure; and stacking the one or both of the composite filler tape and the composite filler fabric onto the third composite foam structure in addition to the first composite foam structure and the second composite foam structure to form the internal portion of the component. 
         [0039]    In a yet further refinement, the method further comprises varying the density in at least one of the first composite foam structure, the second composite foam structure and the third composite foam structure to generate an increased pressure drop at a desired location in the at least one of the first composite foam structure, the second composite foam structure and the third composite foam structure. 
         [0040]    In a still further refinement, the first composite foam structure, the second composite foam structure and the third composite structure form at least part of a serpentine structure. 
         [0041]    In a yet still further refinement, the method further comprises varying the density in the first composite foam structure to generate an increased pressure drop at a desired location in the first composite foam structure. 
         [0042]    In an additional further refinement, the first composite foam structure forms at least part of a serpentine structure. 
         [0043]    In another further refinement, the forming of the first composite foam structure to the desired shape includes forming the first composite foam structure into a serpentine shape. 
         [0044]    In yet another further refinement, the composite is a ceramic matrix composite. 
         [0045]    In still another further refinement, the method further comprises incorporating a metallic spar into the internal portion of the component. 
         [0046]    Embodiments of the present invention include an airfoil for a turbomachine, comprising: a body having an airfoil shape, wherein the body includes; an internal portion of the airfoil having a composite foam cooling passage configured to pass a cooling fluid therethrough; and a plurality of composite wrap plies enveloping the internal portion of the airfoil. 
         [0047]    In a refinement, the airfoil further comprises one or both of a composite filler tape and a composite filler fabric surrounding at least a portion of the composite foam cooling passage, wherein the one or both of the composite filler tape and the composite filler fabric form a part of the internal portion of the airfoil. 
         [0048]    In another refinement, the plurality of composite wrap plies form an airfoil shape around the internal portion of the airfoil. 
         [0049]    In yet another refinement, the composite foam cooling passage includes a controlled density variation configured to generate an increased pressure drop at a desired location. 
         [0050]    In still another refinement, the composite foam cooling passage is formed of a unitary composite foam structure. 
         [0051]    In yet still another refinement, the composite foam cooling passage is formed into a serpentine shape. 
         [0052]    In a further refinement, the composite foam cooling passage is formed of a plurality of composite foam structures arranged together to form the composite foam cooling passage. 
         [0053]    In a yet further refinement, the composite is a ceramic matrix composite. 
         [0054]    In a still further refinement, the airfoil further comprises a metallic spar in the internal portion of the airfoil. 
         [0055]    In a yet still further refinement, the airfoil further comprises a composite filler surrounding at least a portion of the composite foam cooling passage, wherein the composite filler forms a part of the internal portion of the airfoil. 
         [0056]    Embodiments of the present invention include a gas turbine engine, comprising: a compressor; a combustor in fluid communication with the compressor; and a turbine in fluid communication with the combustor, wherein at least one of the compressor and the turbine includes a component having means for cooling the component with a cooling fluid. 
         [0057]    In a refinement, the means for cooling the component includes a composite foam cooling passage. 
         [0058]    In another refinement, the composite foam cooling passage includes a controlled density variation configured to generate an increased pressure drop at a desired location. 
         [0059]    In yet another refinement, the composite is a ceramic matrix composite. 
         [0060]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore, it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.