Abstract:
One embodiment of the present invention is a unique gas turbine engine. Another embodiment is a unique frame for a gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines and gas turbine engine frames. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application 61/291,592, filed Dec. 31, 2009, and is incorporated herein by reference. 
     
    
     GOVERNMENT RIGHTS 
       [0002]    The present application was made with United States government support under Contract No. F33615-03-D-2357 awarded by the United States government. The United States government may have certain rights in the present application. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The present invention relates to gas turbine engines, and more particularly, to gas turbine engine frames. 
       BACKGROUND 
       [0004]    Structures such as frames for gas turbine engines 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 
       [0005]    One embodiment of the present invention is a unique gas turbine engine. Another embodiment is a unique frame for a gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines and gas turbine engine frames. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0007]      FIG. 1  schematically depicts a gas turbine engine having an intermediate frame in accordance with an embodiment of the present invention. 
           [0008]      FIG. 2  is an exploded side view of an intermediate frame for a gas turbine engine in accordance with an embodiment of the present invention. 
           [0009]      FIG. 3  is a cross section of the intermediate frame of  FIG. 2 . 
           [0010]      FIGS. 4A and 4B  are end views of the intermediate frame of  FIG. 2 . 
       
    
    
     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 now to the drawings, and in particular,  FIG. 1 , a non-limiting example of a gas turbine engine  10  in accordance with an embodiment of the present invention is depicted. Engine  10  includes a fan system  12 , an intermediate frame  14 , a compressor system  16 , a combustor  18  and a turbine system  20 . In one form, engine  10  is a multi-spool engine. In other embodiments, engine  10  may be a single spool engine or a multi-spool engine having any number of spools. In one form, engine  10  is a turbofan engine, wherein fan system  12  includes a plurality of fan stages (not shown). In other embodiments, engine  10  may be another type of gas turbine engine, such as a turbojet engine, a turboshaft engine or a turboprop engine, or a turbofan engine having only a single fan stage. 
         [0013]    Fan system  12  is operative to pressurize air received into engine  10 , some of which is directed into compressor system  16  as core flow. The balance of the air pressurized by fan system  12  is directed into a bypass duct system (not shown) and discharged by turbofan engine  10  to generate thrust. In one form, fan system  12  includes two fan stages (not shown). In other embodiments, a greater or lesser number of fan stages may be employed. 
         [0014]    Intermediate frame  14  is operative to direct air pressurized by fan system  12  toward compressor system  16 , and to transmit engine  10  mechanical loads to an engine mount system  22 , such as an intermediate engine mount. Although depicted as being disposed between fan system  12  and compressor system  16 , it will be understood that in other embodiments intermediate frame  14  may take other forms and/or may be located in other positions. For example, in other embodiments, intermediate frame  14  may be located between compressor  16  and combustor  18 ; between combustor  18  and turbine system  20 ; and/or may be considered a portion of compressor system  16  or turbine system  20 , and/or may house all or a portion of one or more of fan system  12 , compressor system  16 , combustor  18  and turbine system  20 . 
         [0015]    Compressor system  16  is operative to compress the core flow discharged by fan system  12 . In one form, compressor system  16  includes two multi-stage compressors (not shown), each of which includes a plurality of blades and vanes in a plurality of stages for compressing air received by compressor system  16 . In other embodiments, compressor system  16  may be in the form of a single multi-stage compressor. In still other embodiments, compressor system  16  may include more than two compressors, e.g., a low pressure (LP) compressor, an intermediate pressure (IP) compressor and a high pressure (HP) compressor. 
         [0016]    Combustor  18  is in fluid communication with compressor system  16 . Combustor  18  is operative add fuel and combust air pressurized by compressor system  16 . 
         [0017]    Turbine system  20  is in fluid communication with combustor  18 . Turbine system  20  operative to expand the hot gases received from combustor  18  and to extract energy therefrom to drive compressor system  16  and fan system  12 . In one form, turbine system  20  includes two turbines, i.e., an LP turbine and an HP turbine. In other embodiments, a greater or lesser number of turbines may be employed. Each turbine includes one or more stages of blades and vanes. 
         [0018]    Referring now to  FIG. 2 , an exploded view of a non-limiting example of intermediate frame  14  is depicted and described. Intermediate frame  14  includes a metallic inner hub  24 , a metallic outer construction  26 , a composite flowpath  28 , a metallic flange  30 , a plurality of service tubes  34 , a plurality of metallic struts  32  and a plurality of strut caps  36 . 
         [0019]    Metallic inner hub  24  is a structural component of intermediate frame  14  and houses, for example, a bearing sump and a gearbox, for which metallic inner hub  24  provides structural support. In one form, the bearing sump includes mainshaft bearings, such as rolling element bearings, that support all or part of one or more engine  10  rotors. Metallic inner hub  24  is formed of a metallic material, such as a titanium, aluminum or magnesium alloy. 
         [0020]    Metallic inner hub  24  includes a plurality of strut pedestals  38  and a contoured outer surface  39 . Strut pedestals  38  extend outward from contoured outer surface  39 . In one form, strut pedestals  38  extend radially outward from contoured outer surface  39 . In other embodiments, strut pedestals may extend outward from contoured outer surface  39  in other fashions, e.g., tangentially from contoured outer surface  39  or tangentially from a reference diameter. Strut pedestals  38  are configured for engagement with service tubes  34  and metallic struts  32 . In one form, strut pedestals  38  and outer surface  39  are part of an integral unit forming metallic inner hub  24 . In other embodiments, strut pedestals  38  and/or outer surface  39  may be formed as separate components and assembled together to form metallic inner hub  24 . In one form, outer surface  39  is generally parallel to an inner flowpath wall inside intermediate frame  14  (e.g., inner wall  52  of composite flowpath  28 , described below). In other embodiments, outer surface  39  may form part of the inner flowpath surface. 
         [0021]    Metallic outer construction  26  is formed of a metallic material, such as a titanium, aluminum or magnesium alloy. Metallic outer construction  26  is adapted to interface with strut caps  36  and with engine mount system  22 . Metallic outer construction  26  is operative to maintain the circumferential orientation of metallic struts  32  and service tubes  34 . Metallic outer construction is also operative to transmit engine  10  mechanical loads to engine mount system  22 . 
         [0022]    Composite flowpath  28  is radially disposed between metallic inner hub  24  and metallic outer construction  26 . Composite flowpath  28  is formed of a composite material. In one form, the composite material is a carbon bismaleimide composite. A non-limiting example of a carbon bismaleimide composite is Cycom 5250-4 BMI, commercially available from Cytec Industries Inc., headquartered in Woodland Park, N.J., USA. Other composite materials may be used in other embodiments, e.g., including ceramic matrix composites, metal matrix composites, organic matrix composites and/or carbon-carbon composites. In one form, composite flowpath  28  is formed via a resin transfer molding (RTM) process. In other embodiments, other manufacturing processes and techniques suitable for use in manufacturing composites may be employed in addition to or in place of RTM. In one form, composite flowpath  28  has a cavity  42  adapted to receive metallic inner hub  24 . 
         [0023]    Metallic flange  30  is adapted to interface with both composite flowpath  28  and with metallic inner hub  24 . Metallic flange  30  is operative to secure composite flowpath  28  to metallic inner hub  24 . Service tubes  34  and metallic struts  32  of intermediate frame  14  extend between metallic inner hub  24 , e.g., strut pedestals  38 , and outer construction  26 . Metallic struts  32  are formed of a metallic material, such as a titanium, aluminum or magnesium alloy. Engine mechanical loads, such as rotor loads, inertial loads and engine weight loads are reacted by metallic inner hub  24  for transmission to engine mount system  22  via strut pedestals  38 . Strut pedestals  38  transmit the mechanical loads from metallic inner hub  24  into metallic struts  32 . 
         [0024]    Strut caps  36  are adapted to interface with, service tubes  34  and metallic outer construction  26 , and may also include interface features for connection to engine externals, such as tubing and a wiring harness. Metallic struts  32  transmit the mechanical loads to metallic outer construction  26  via strut caps  36 . The loads are transmitted from metallic outer construction  26  to mount system  22 . 
         [0025]    Strut pedestals  38  and strut caps  36  are adapted to interface with service tubes  34 . Service tubes  34 , which may also be referred to as transfer tubes, provide passages between metallic inner hub  24  and metallic outer construction  26  for the provision of services to and from metallic inner hub  24 . For example, in some embodiments, service tubes  34  are structured to conduct one or more of pressurized lube oil, scavenge oil, seal charging air, sump vent air, cooling air, one or more sensors, one or more shafts, such as a tower shaft  40  for transmitting power to an accessory gearbox, and/or one or more communications links and/or power cables between metallic inner hub  24  and metallic outer construction  26 . The communications links include, for example, wired and/or optical links to transmit sensor data and/or control inputs, as well as wired links to transmit electrical power. In one form, service tubes  34  are fitted on either end into holes in metallic inner hub  24  and strut caps  36 , and are sealed, e.g., with an o-ring or gasket. 
         [0026]    Referring now to  FIGS. 3 ,  4 A and  4 B, the exemplary intermediate frame of  FIG. 2  is depicted as assembled.  FIG. 3  is a cross section of intermediate frame  14 , and  FIGS. 4A and 4B  are end views of intermediate frame  14 . 
         [0027]    Composite flowpath  28  is disposed radially between metallic inner hub  24  and metallic outer construction  26 . Composite flowpath  28  defines flowpaths for the working fluid of engine  10 . A flowpath is a passageway that channels bulk working fluid flow through engine  10 , i.e., core airflow and bypass airflow, as opposed to fluid passages that transmit relatively small quantities of fluids, e.g., cooling air, pressure balance air, vent air and seal charging air, such as service tubes  34 . As illustrated in  FIG. 3 , composite flowpath  28  defines both a primary flowpath  46  and a secondary flowpath  48 . In other embodiments, a greater or lesser number of flowpaths may be defined by composite flowpath  28 . In one form, secondary flowpath  48  is disposed radially outward of primary flowpath  46 , although other arrangements may be employed in other embodiments. In one form, primary flowpath  46  is operative to conduct fan system  12  discharge flow to compressor system  16 , and secondary flowpath  48  is operative to conduct fan system  12  discharge flow as a bypass flow. 
         [0028]    Composite flowpath  28  includes a composite primary flowpath outer wall  50  and a composite primary flowpath inner wall  52  spaced apart from outer wall  50 . Inner wall  52  is disposed radially inward of outer wall  50 . Outer wall  50  and inner wall  52  define primary flowpath  46 . Composite flowpath  28  also includes a composite secondary flowpath outer wall  54  and a composite secondary flowpath inner wall  56  spaced apart from outer wall  54 . Inner wall  56  is disposed radially inward of outer wall  54 . Outer wall  54  and inner wall  56  define secondary flowpath  48 . 
         [0029]    Composite flowpath  28  includes a plurality of hollow composite struts  44 . Composite struts  44  are subdivided two groups: inner composite struts  44 A and outer composite struts  44 B. In one form, inner composite struts  44 A and outer composite struts  44 B are hollow. In other embodiments, some or all of inner composite struts  44 A and outer composite struts  44 B may be solid. 
         [0030]    Composite struts  44 A extend between composite primary outer wall  50  and composite primary inner wall  52 . Composite struts  44 A are adapted to receive strut pedestals  38 , metallic struts  32  and service tubes  34 . Composite struts  44 B extend between composite secondary flowpath outer wall  54  and composite secondary flowpath inner wall  56 . Composite struts  44 B are adapted to receive metallic struts  32  and service tubes  34 . In one form, composite flowpath  28  is integrally formed as a unitary single piece structure, including outer wall  50 , inner wall  52 , outer wall  54 , inner wall  56 , and composite struts  44 A and  44 B. In other embodiments composite flowpath  28  may be in the form of discrete composite components that are assembled together. 
         [0031]    Composite flowpath  28  and metallic inner hub  24  are adapted to interface and transmit aerodynamic loads on composite flowpath  28  to metallic inner hub  24 . For example, loads resulting from pressures and flows in primary flowpath  46  and secondary flowpath  48  are transmitted to metallic inner hub  24 . In addition loads resulting from the pressures in cavities of composite flowpath  28 , e.g., cavity  42  and a cavity  58  disposed between primary flowpath outer wall  50  and secondary flowpath inner wall  56 , are transmitted to metallic inner hub  24 . In one form, composite struts  44 A and strut pedestals  38  are adapted to jointly form an interface for transmitting aerodynamic loads from composite flowpath  28  to metallic inner hub  24 . In other embodiments, intermediate frame  14  may be configured to transmit aerodynamic loads from composite flowpath  28  to other structures, such as contoured outer surface  39  or a face of metallic hub  24 , one or more of metallic struts  32  and/or metallic outer construction  26 . 
         [0032]    In one form, intermediate frame  14  is assembled by inserting inner metallic hub  24  into cavity  42  of composite flowpath  18 . Composite flowpath  28  is secured onto metallic inner hub  24  with metallic flange  30 . For example, in some embodiments, metallic flange  30  is bolted onto metallic inner hub  24  to clamp composite flowpath  28  between metallic inner hub  24  and metallic flange  30 . Metallic struts  32  and service tubes  34  are inserted into composite struts  44  for interface with metallic inner hub  24 , e.g., via strut pedestals  38 . Strut caps  36  are then installed over metallic struts  32  and service tubes  34 . Metallic outer construction  26  is then assembled over strut caps  36  and secured to strut caps  36 , e.g., using bolts (not shown). 
         [0033]    Metallic inner hub  24 , metallic struts  32  and metallic outer construction  26 , as assembled, form a loadpath that transfers engine mechanical loads between metallic inner hub  24  and metallic outer construction  26 , and from metallic outer construction to engine mount system  22 . The loadpath passes through the metallic structures of intermediate frame  14 , and bypasses composite flowpath  28 . By being divorced from the loadpath, composite flowpath  28  does not require the strength of metallic materials, which allows the use of composite materials to form flowpath  28 , which may in some embodiments reduce the weight of intermediate frame  14  relative to similar structures formed solely or primarily of metallic materials. 
         [0034]    Embodiments envisioned include a gas turbine engine frame, including a metallic inner hub; a metallic outer construction; and a composite flowpath disposed between the metallic inner hub and the metallic outer construction, the composite flowpath defining a primary flowpath for a working fluid of the gas turbine engine. 
         [0035]    In a refinement, the gas turbine engine frame also includes metallic struts extending between the metallic inner hub and the metallic outer construction, wherein the metallic inner hub, the metallic struts and the metallic outer construction are assembled to form a loadpath to transfer engine mechanical loads between the metallic inner hub and the metallic outer construction. In another refinement, the loadpath bypasses the composite flowpath. In a further refinement, the gas turbine engine frame is structured to transmit aerodynamic loads from the composite flowpath to one of the metallic inner hub, the metallic struts and the metallic outer construction. 
         [0036]    In another refinement, the composite flowpath is formed as a single piece structure. 
         [0037]    In yet another refinement, the composite flowpath includes a composite inner flowpath wall and a composite outer flowpath wall spaced apart from the composite outer flowpath wall, and wherein the composite inner flowpath wall and the composite outer flowpath wall define the primary flowpath. In one form, the composite flowpath includes a plurality of composite struts, wherein at least a portion of each composite strut extends between the composite inner flowpath wall and the composite outer flowpath wall. In a refinement, the composite inner flowpath wall, the composite outer flowpath wall and the plurality of composite struts are integrally formed. 
         [0038]    Embodiments also include a gas turbine engine, including a compressor; a turbine; and an engine frame, the engine frame including a metallic load-bearing structure and a composite flowpath, wherein the metallic load-bearing structure defines a loadpath operative to transmit engine mechanical loads to an engine mount of the gas turbine engine, and wherein the composite flowpath is divorced from the loadpath. 
         [0039]    In a refinement, the composite flowpath defines a primary flowpath for a working fluid of the gas turbine engine. In a further refinement, the composite flowpath includes a primary flowpath outer wall and a primary flowpath inner wall disposed radially inward of the primary flowpath outer wall, wherein the primary flowpath outer wall and the primary flowpath inner wall define the primary flowpath. 
         [0040]    In another refinement, the composite flowpath further defines a secondary flowpath for the working fluid of the gas turbine engine. In one form, the composite flowpath includes a secondary flowpath outer wall and a secondary flowpath inner wall disposed radially inward of the secondary flowpath outer wall, and wherein the secondary flowpath inner wall and the secondary flowpath outer wall define the secondary flowpath. In a refinement, the composite flowpath includes a composite strut extending through the secondary flowpath. In another refinement, the metallic load-bearing structure includes a metallic strut disposed within the composite strut, wherein the metallic strut is operative to transmit the engine mechanical loads through the secondary flowpath. 
         [0041]    In another refinement, the metallic load-bearing structure includes a metallic inner hub disposed radially inward of the composite flowpath; a metallic outer construction disposed radially outward of the composite flowpath; and a metallic strut extending between the metallic inner hub and the metallic outer construction. 
         [0042]    In yet another refinement, the gas turbine engine includes a service tube extending between the metallic inner hub and the metallic outer construction, wherein the service tube is structured to conduct between the metallic inner hub and the metallic outer construction at least one of pressurized lube oil; scavenge oil, seal charging air; sump vent air, cooling air, a sensor, and a communications link. In one form, the composite flowpath includes a composite strut disposed at least partially around the service tube. In one form, the composite flowpath is formed as a single piece structure. 
         [0043]    In still another refinement, the composite flowpath includes a composite strut disposed at least partially around the metallic strut. 
         [0044]    Embodiments also include a gas turbine engine, including a compressor; a turbine; and an engine frame, the engine frame including composite means for defining a primary flowpath for a working fluid of the gas turbine engine; and means for transmitting engine mechanical loads to an engine mount of the gas turbine engine, wherein the composite means are divorced from the engine mechanical loads. 
         [0045]    In a refinement, the engine frame also includes composite means for defining a secondary flowpath for the working fluid of the gas turbine engine. 
         [0046]    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.