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

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to airfoils, and more particularly, to airfoils for gas turbine engines and other turbomachines. 
       BACKGROUND 
       [0002]    Airfoils for gas turbine engines and other turbomachines 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 
       [0003]    One embodiment of the present invention is a unique airfoil for a turbomachine. Another embodiment is a unique gas turbine engine. Yet another embodiment is a method for manufacturing an airfoil for a turbomachine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for airfoils and turbomachinery. 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 
         [0004]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0005]      FIG. 1  schematically illustrates some aspects of a non-limiting example of a lift engine system in accordance with an embodiment of the present invention. 
           [0006]      FIG. 2  illustrates some aspects of a non-limiting example of an airfoil in accordance with an embodiment of the present invention. 
           [0007]      FIGS. 3 and 4  illustrate some aspects of a non-limiting example of an airfoil in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    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. 
         [0009]    Referring to the drawings, and in particular  FIG. 1 , there are illustrated some aspects of a non-limiting example of a lift engine system  10  in accordance with an embodiment of the present invention. Lift engine system  10  is configured to provide propulsive thrust for an aircraft  12 , such as a short takeoff and vertical landing (STOVL) aircraft. Lift engine system  10  includes turbomachinery in the form of a gas turbine engine  14  and a lift fan system  16 . In other embodiments, gas turbine engine  14  may be employed without lift fan system  16  as a propulsion engine for one or more various types of aircraft. In still other embodiments, gas turbine engine  14  may be any gas turbine engine, e.g., adapted for use as an aerospace engine, a marine engine, an industrial engine or the like, and may be in the form of a turbofan engine, a turboshaft engine, a turboprop engine, a turbojet engine or a hybrid engine. 
         [0010]    In one form, gas turbine engine  14  includes a fan  18 , a compressor  20 , a combustor  22  and a turbine  24 . Lift fan system  16  includes a lift fan  26 , a shaft system  28 , and a lift thrust output system in the form of a vanebox  30 . In various embodiments, fan  18 , compressor  20  and turbine  24  may include one or more rotors, each of which may have one or more blade stages and vane stages. The number of rotors and stages for each of fan  18 , compressor  20  and turbine  24  may vary with the needs of the particular application. Lift fan  26  is coupled to gas turbine engine  14  via shaft system  28 . 
         [0011]    Fan  18  is configured to pressurize air received at the inlet of engine  14 . Compressor  20  is in fluid communication with fan  18 , and is configured to compress air discharged by fan  18 . Combustor  22  is in fluid communication with compressor  20 , and is configured to receive the air discharged by compressor, add fuel, and combust an air fuel mixture. Turbine  24  is in fluid communication with combustor  22 , and is configured to receive the hot gases exiting combustor  22 , and to extract energy therefrom to power fan  18 , compressor  20  and lift fan  26  via one or more shafts (not shown). Turbine  24  may also be configured to provide power for other components (not shown). Power is supplied from gas turbine engine  14  to lift fan  26  via shaft system  28 . Lift fan  26  is adapted for mounting to aircraft  12 , and discharges air through vanebox  30  to provide thrust e.g., for STOVL aircraft  12 , which in some embodiments may be vectored thrust. 
         [0012]    Gas turbine engine  14  and lift fan system  16  employ 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  14  and lift fan system  16 . The airfoils are used in fan  18 , compressor  20 , turbine  24 , lift fan  26  and vanebox  30 . It is often desirable that the airfoils be light in weight in order to manage the weight of engine  14  and system  16 . In addition, in many cases, it is desirable that the airfoils be robust for operational purposes, but also less prone to damage downstream components should an airfoil separate from its mounting structure and pass through downstream components of part or all of engine  14  and/or lift fan system  16 . Accordingly, embodiments of the present invention envision airfoils having a foam core, such as a metal foam core, with a composite skin surrounding the foam core. Such an airfoil may weigh less than conventional solid metal or hollow metal airfoils. 
         [0013]    Referring to  FIG. 2 , some aspects of a non-limiting example of an airfoil  40  in accordance with an embodiment of the present invention is depicted. Airfoil  40  includes a metal foam core  42  and a composite skin  44  disposed over metal foam core  42 , forming an airfoil shape. A portion of composite skin  44  is removed in the illustration of  FIG. 2  in order to illustrate aspects of metal foam core  42  and composite skin  44 . In one form, metal foam core  42  is 10% dense, that is, 10% of the density of a solid metal formed of the same material. In other embodiments, other density values may be employed. The type of metal used in metal foam core  42  may vary with the needs of the application. In one form, metal foam core  42  is formed of a titanium alloy. In other embodiments, other metals, alloyed or not, may be employed, e.g., an aluminum alloy. 
         [0014]    In one form, airfoil  40  is a fan blade adapted for use in fan  18 . In other embodiments, airfoil  40  may be employed as a compressor  20  airfoil, a turbine  24  airfoil, a lift fan  26  airfoil or a vanebox  30  airfoil, and may be a blade or a vane. In one form, airfoil  40  is configured to be more readily “sliced up” by downstream components of engine  14  and/or lift fan system  16 , as compared to solid or hollow metal airfoils (having on the order of 100% density of the metal) in the event the airfoil separates from its mounting and is ingested by one or more downstream components. In one form, extending from airfoil  40  is an attachment feature  46  configured to attach airfoil  40  to a fan  18  rotor (not shown). 
         [0015]    In one form, attachment feature  46  is formed as an extension of metal foam core  42  and composite skin  44 . In various such embodiments, attachment feature  46  may have a different metal density than metal foam core  42 , e.g., may be fully dense or may transition from one density value to another with increasing proximity to metal foam core  42 . In other embodiments, attachment feature  46  may be formed separately and affixed to airfoil  40  using any suitable bonding or other material joining technique. 
         [0016]    In one form, metal foam core  42  is a closed-cell foam. In other embodiments, metal foam core  42  may be an open-cell foam or a combination of open-cell foam and closed-cell foam. In one form, metal foam core  42  is formed as an airfoil shape (except attachment feature  46 ). In other embodiments, metal foam core  42  may be formed as another shape, and subsequently machined or otherwise processed into an airfoil shape. 
         [0017]    Metal foam core  42  includes a plurality of outermost voids  48 . In one form, voids  48  are formed as part of the foam structure of metal foam core  42 . In other embodiments, voids  48  may be formed in metal foam core  42  subsequent to metal foam core  42  being formed. In one form, composite skin  44  includes a composite material layer  50  that extends into and at least partially fills some or all of outermost voids  48 , affixing composite skin  44  to metal foam core  42 . Bonding agents may or may not be used to increase the bond strength, depending upon the application. In one form, composite material  50  is a polyamide material. In other embodiments, other composite materials may be employed, e.g., depending upon mechanical, thermal and/or aerodynamic loading, and/or ambient conditions at the location in engine  14  and/or lift fan system  16  where airfoil  40  is intended to operate. In one form, composite material layer  50  is glass-filled. In other embodiments, composite material layer  50  may employ other fillers in addition to or in place of glass. In still other embodiments, composite material layer  50  may not employ any fillers. 
         [0018]    In one form, composite skin  44  includes another composite material layer  52  overlaying composite material layer  50 . In one form, composite material layer  52  is a carbon-fiber composite having a carbon fabric included therein. In other embodiments, composite material layer  52  may be one or more other types of composite materials. In one form, composite layer  52  is bonded to composite material layer  50 . In one form, composite layer  52  is configured to reinforce composite material layer  50 . In other embodiments, composite material layer  52  may also or alternatively be configured otherwise. For example and without limitation, composite material layer  52  may be configured for erosion and/or corrosion protection. Although described herein as being bonded to composite material layer  50 , in other embodiments, composite material layer  52  may be bonded directly to metal foam core  42 . For example, some embodiments may include composite layer  52  as part of composite skin  44 , but without also having composite layer  50  as part of composite skin  44 . 
         [0019]    Airfoil  40  may be manufactured by forming a metal foam core  42  into an airfoil shape. For example and without limitation, metal foam may be formed into an airfoil via the use of a mold, may be formed into a rough shape and subsequently machined or otherwise processed into an airfoil shape, or may be formed into an airfoil shape via a freeform manufacturing technique, such as a stereolithography technique. In other embodiments, metal foam core may not have an airfoil shape or a complete airfoil shape, in which case composite skin  44  may be used to form the airfoil shape. Metal foam core  42  is manufactured to include outermost voids  48 . 
         [0020]    After metal foam core  42  is formed into an airfoil shape, composite skin  44  is affixed to metal foam core  42 . Composite material layer  50  is formed by directing composite material, e.g., polyamide, into outermost voids  48 , at least partially filling voids  68 , and thereby affixing composite skin  44  to metal foam core  42 . In various embodiments, only some of voids  48  are filled or partially filled, e.g., depending on the size of the void. In one form, the composite material is injection molded into voids  48 . In other embodiments, other techniques may be employed to direct the composite material of composite layer  50  into outermost voids  48 . Composite material layer  50  may be filled (e.g. glass-filled) or may be unfilled. In one form, composite layer  52 , e.g., a carbon fiber composite, is formed and bonded onto composite material layer  50 . In various other embodiments, composite layer  52  may not be employed, or may be bonded or otherwise affixed to metal foam core  42 . 
         [0021]    Referring to  FIGS. 3 and 4  some aspects of a non-limiting example of an airfoil  60  in accordance with an embodiment of the present invention is depicted. Airfoil  60  includes a metal foam core  62  and a composite skin  64  disposed over metal foam core  62 , forming an airfoil shape. A portion of composite skin  64  is removed in the illustration of  FIG. 4  in order to illustrate aspects of metal foam core  62  and composite skin  64 . In one form, metal foam core  62  is 10% dense. In other embodiments, other density values may be employed. The type of metal used in metal foam core  42  may vary with the needs of the application. In one form, metal foam core  42  is formed of a titanium alloy. In other embodiments, other metals, alloyed or not, may be employed, e.g., an aluminum alloy. 
         [0022]    In one form, airfoil  60  is configured as a vane that is configured for use in vanebox  30 . In other embodiments, airfoil  60  may be employed as a compressor  20  airfoil, a turbine  24  airfoil, a lift fan  26  airfoil, and may be a blade or a vane. In one form, extending from airfoil  60  is an attachment feature  66  configured to attach airfoil  60  to vanebox  30 . In one form, attachment feature  66  is formed separately and affixed to airfoil  60 , e.g., using a suitable bonding or other material joining technique. In other embodiments, attachment feature  66  may be formed as an extension of metal foam core  62  and composite skin  64 . In such embodiments, attachment feature  66  may have a different metal density than the metal foam  62 , e.g., may be fully dense or may transition from one density value to another with increasing proximity to metal foam core  62 . In one form, metal foam core  62  is a closed-cell foam. In other embodiments, metal foam core  62  may be an open-cell foam or a combination of open-cell foam and closed-cell foam. In one form, metal foam core  62  is formed as an airfoil shape (except attachment feature  46 ). In other embodiments, metal foam core  62  may be formed as another shape, and subsequently machined or otherwise processed into an airfoil shape. 
         [0023]    Metal foam core  62  includes a plurality of outermost voids  68 . In one form, voids  68  are formed as part of the foam structure of metal foam core  62 . In other embodiments, voids  68  may be formed in metal foam core  62  subsequent to metal foam core  62  being formed. In one form, composite skin  64  includes a composite material layer  70  that extends into and at least partially fills some or all of outermost voids  68 , affixing composite skin  64  to metal foam core  62 . Bonding agents may or may not be used to increase the bond strength, depending upon the application. In one form, composite material  70  is a polyamide material. In other embodiments, other composite materials may be employed, e.g., depending upon mechanical, thermal and/or aerodynamic loading, and/or ambient conditions at the location in engine  14  and/or lift fan system  16  where airfoil  60  is intended to operate. In one form, composite material layer  70  is glass-filled. In other embodiments, composite material layer  70  may employ other fillers in addition to or in place of glass. In still other embodiments, composite material layer  70  may not employ any fillers. 
         [0024]    In one form, composite skin  64  includes another composite material layer  72  overlaying composite material layer  70 . In one form, composite material layer  72  includes a carbon fabric in a carbon-fiber composite. In other embodiments, composite material layer  72  may be one or more other types of composite materials. In one form, composite layer  72  is bonded to composite material layer  70 . In one form, composite layer  72  is configured to reinforce composite material layer  70 . In other embodiments, composite material layer  72  may also or alternatively be configured otherwise. For example and without limitation, composite material layer  72  may be configured for erosion and/or corrosion protection. Although described herein as being bonded to composite material layer  70 , in other embodiments, composite material layer  72  may be bonded directly to metal foam core  62 . For example, some embodiments may include composite layer  72  as part of composite skin  64 , but without also having composite layer  70  as part of composite skin  64 . 
         [0025]    In one form, airfoil  60  may be manufactured in the same manner set forth above with respect to airfoil  40 . In other embodiments, airfoil  60  may be manufactured using other processes and techniques. 
         [0026]    Embodiments of the present invention include an airfoil for a turbomachine, comprising: a metal foam core; and a composite skin disposed over the metal foam core and forming an airfoil shape. 
         [0027]    In a refinement, the composite skin includes a carbon fiber composite. 
         [0028]    In another refinement, the carbon fiber composite includes a carbon fabric. 
         [0029]    In yet another refinement, the metal foam core has a plurality of outermost voids, and the composite skin includes a first composite material extending into and at least partially filling at least some of the plurality of outermost voids. 
         [0030]    In still another refinement, the composite skin includes a second composite material overlaying the first composite material. 
         [0031]    In yet still another refinement, the second composite material is a carbon fiber composite. 
         [0032]    In an additional refinement, the second composite material is bonded to the first composite material. 
         [0033]    In a further refinement, the first composite material includes a polyamide. 
         [0034]    In a yet further refinement, the polyamide is glass filled. 
         [0035]    In a still further refinement, the turbomachine is a vanebox, and the airfoil is a vane configured for use in the vanebox. 
         [0036]    In a yet still further refinement, the airfoil further comprises at least one attachment feature configured to attach the airfoil to a component of the turbomachine. 
         [0037]    Embodiments of the present invention include a gas turbine engine, comprising: at least one of a fan and 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 fan, compressor and the turbine include an airfoil having a metal foam core and a composite skin disposed over the metal foam core. 
         [0038]    In a refinement, the airfoil is a fan blade. 
         [0039]    In another refinement, the metal foam core has an airfoil shape. 
         [0040]    In yet another refinement, the metal foam core is a closed-cell foam. 
         [0041]    In still another refinement, the composite skin includes a first composite material reinforced by a second composite material. 
         [0042]    In yet still another refinement, the first composite material is a polyamide material. 
         [0043]    In an additional refinement, the second composite material includes a carbon fabric. 
         [0044]    In a further refinement, the airfoil is configured as a vane. 
         [0045]    Embodiments of the present invention include a method for manufacturing an airfoil for a turbomachine, comprising: forming a metal foam core into an airfoil shape; and affixing a composite skin to the metal foam core. 
         [0046]    In a refinement, the metal foam core is formed to include a plurality of outermost voids, and wherein the composite skin is formed at least in part by injection molding a composite material into at least some of the plurality of outermost voids. 
         [0047]    In another refinement, the method further comprises bonding a carbon fiber composite to the composite material. 
         [0048]    In yet another refinement, the metal foam core is machined into an airfoil shape. 
         [0049]    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.