Abstract:
A nacelle assembly and a method for assembling the same is provided. The nacelle assembly includes an inner barrel and an outer structure comprising a highlight and an outer aft section, wherein the highlight is defined by a forward end of the outer structure, wherein the outer aft section includes a point defined by a maximum diameter of the nacelle assembly, wherein the nacelle assembly extends at least between the highlight and the point.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to gas turbine engine nacelle assemblies and, more particularly, to methods and apparatus for an integrated inlet design for a nacelle assembly. 
         [0002]    Some known nacelle assemblies used with turbine engines include a plurality of components that disrupt aerodynamic flow of the nacelle assembly with a plurality of circumferential and axial gaps and steps defined between the components. For example, at least one known nacelle assembly includes an inlet lip, an inlet outer barrel, and a fan cowl that define an outer flow surface of the nacelle assembly. Moreover, within some nacelle assemblies, some known components include a plurality of segments, which define additional gaps and steps on the outer flow surface. For example, at least one known nacelle assembly used in a large high-bypass engine includes an inlet lip defined by a plurality of radial segments. 
         [0003]    Within some turbine engines, at least some of the components and at least some segments of the components used in the nacelle assembly are coupled in position within the nacelle assembly with a plurality of mechanical fasteners. For example, mechanical fasteners may secure a bulkhead that is positioned internal to the inlet lip. The mechanical fasteners, because of their orientation, also disrupt aerodynamic flow of the nacelle assembly. More specifically, in the bulkhead example, heads of the mechanical fasteners are exposed on the outer surface of the nacelle assembly and are positioned directly in the outer flow path. In addition to the exposed heads of the mechanical fasteners, other gaps and/or steps in the nacelle assembly may inhibit laminar flow over the outer flow surface of the nacelle assembly, and may increase aerodynamic drag. Operating a turbine engine with increased aerodynamic drag may reduce fuel burn efficiency. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    In one aspect, a method for assembling a nacelle assembly is provided. The method includes providing an outer structure that extends at least between a highlight defined by a forward end of the outer structure and a point defined by a maximum diameter of the nacelle assembly and coupling the outer structure to an inner barrel. 
         [0005]    In another aspect, an outer structure of a nacelle assembly is provided. The outer structure includes a highlight defined by a forward end of the outer structure and an outer aft section that includes a point defined by a maximum diameter of the nacelle assembly, wherein the nacelle assembly extends at least between the highlight and the point. 
         [0006]    In yet another aspect, a nacelle assembly is provided. The nacelle assembly includes an inner barrel and an outer structure comprising a highlight and an outer aft section, wherein the highlight is defined by a forward end of the outer structure, wherein the outer aft section includes a point defined by a maximum diameter of the nacelle assembly, wherein the nacelle assembly extends at least between the highlight and the point. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of an exemplary aircraft; 
           [0008]      FIG. 2  is a cross-sectional view of a portion of an exemplary turbine engine that may be used with the aircraft shown in  FIG. 1 ; 
           [0009]      FIG. 3  is a schematic illustration of a nacelle assembly used with the turbine engine shown in  FIG. 2 ; 
           [0010]      FIG. 4  is another schematic illustration of the nacelle assembly shown in  FIG. 3 ; and 
           [0011]      FIG. 5  is a schematic illustration of an outer structure used with the nacelle assembly shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    The systems and methods described herein provide an exemplary integrated inlet design that defines an aerodynamic nacelle assembly design. The description should enable one of ordinary skill in the art to make and use the disclosure, and the description describes several embodiments, adaptations, variations, alternatives, and uses of the disclosure, including what is presently believed to be the best mode of carrying out the disclosure. The disclosure is described herein as being applied to a preferred embodiment, namely, an integrated inlet design. 
         [0013]      FIG. 1  is a schematic illustration of an exemplary aircraft  8  that includes at least one turbine engine  10  used to provide thrust for aircraft  8 . In the exemplary embodiment, turbine engine  10  is coupled to a wing  11 . More specifically, turbine engine  10  is coupled to a wing pylon (not shown) at wing  11 . In an alternate embodiment, turbine engine  10  is coupled to a tail  13 . More specifically, turbine engine  10  is coupled to a fuselage (not shown) at tail  13 . 
         [0014]      FIG. 2  is a cross-sectional view of a portion of turbine engine  10 . In the exemplary embodiment, turbine engine  10  includes a fan assembly  16  that is rotatably coupled about a longitudinal centerline axis  32 . In the exemplary embodiment, fan assembly  16  is positioned at a forward end  33  of turbine engine  10 . In an alternative embodiment, fan assembly  16  is positioned at an aft end  35  of turbine engine  10 . Fan assembly  16  includes a plurality of rows of fan blades  19  positioned within a nacelle assembly  12 . In one embodiment, nacelle assembly  12  houses various operating components (not shown) of turbine engine  10 . 
         [0015]    In the exemplary embodiment, turbine engine  10  also includes a core engine  17  that is positioned downstream from fan assembly  16 . Core engine  17  includes a compressor  18 , a combustor  20 , and a turbine  22  that is coupled to compressor  18  via a core rotor shaft  26 . 
         [0016]    During operation, core engine  17  generates combustion gases that are channeled downstream to a turbine  24  which extracts energy from the gases for powering fan assembly  16  through a shaft  28 . 
         [0017]      FIGS. 3 and 4  are schematic illustrations of nacelle assembly  12 . In the exemplary embodiment as shown in  FIG. 3 , nacelle assembly  12  is generally annular and defines an opening  32  sized and configured to channel air through nacelle assembly  12 . Nacelle assembly  12  has a diameter  34  at forward end  33  measured with respect to an inner surface  43  that is smaller than a maximum diameter  36  of an outer surface of nacelle assembly  12 . 
         [0018]    Nacelle assembly  12  includes an inner barrel  38  and an outer structure  40 . In the exemplary embodiment, outer structure  40  is fabricated from a continuous fiber reinforced thermoplastic material. Alternatively, outer structure  40  may be fabricated from a continuous fiber reinforced thermoset material. In one embodiment, outer structure  40  incorporates an integral surfacing film to facilitate protecting nacelle assembly  12  from lighting strikes. 
         [0019]    Outer structure  40  includes a highlight  42  that is defined by forward end  33  of outer structure  40 , an outer aft section  44  that is defined by highlight  42 , and an inner aft section  46  that is defined by highlight  42 . Outer aft section  44  includes a point  45  on an outer surface  47  defined by the maximum diameter  36  of nacelle assembly  12 . In another embodiment, outer structure  40  is coupled to a hoop frame (not shown) at an aft end  35  of outer aft section  44  proximate to a fan cowl  54 , such that the hoop frame facilitates coupling outer structure  40  to fan cowl  54 . 
         [0020]    In the exemplary embodiment as shown in  FIG. 4 , inner aft section  46  includes a first flange  48  that is used to couple outer structure  40  to inner barrel  38 . In another embodiment, outer structure  40  includes a second flange  50  that is used to couple outer structure  40  to a fan case  53 . 
         [0021]    In the exemplary embodiment, nacelle assembly  12  includes a plurality of bulkheads  57 ,  58 , and  59  that facilitate structurally supporting nacelle assembly  12 . Bulkheads  57 ,  58 , and  59  also facilitate absorbing any aftward forces induced to outer surface  47  of outer structure  40 , such as may be created during a bird-strike for example. In the exemplary embodiment, bulkhead  57  is coupled to outer aft section  44  and inner aft section  46 , bulkhead  58  is coupled to outer aft section  44  and inner barrel  38 , and bulkhead  59  is coupled to outer aft section  44  and fan case  53 . In the exemplary embodiment, bulkhead  59  is coupled to an aft end  35  of outer aft section  44  such that bulkhead  59  facilitates coupling outer structure  40  to fan cowl  54 . Bulkheads  57 ,  58 , and  59  may be coupled through a plurality of coupling processes such as through a mechanical fastening process, a thermoplastic welding process, and an adhesive bonding process. 
         [0022]      FIG. 5  is a schematic illustration of outer structure  40 . In the exemplary embodiment, outer structure  40  includes at least one stiffener  56  that is oriented either circumferentially and/or longitudinally to facilitate structurally supporting outer aft section  44 . In the exemplary embodiment, stiffener  56  is an independent component that is coupled to inner surface  43  of outer structure  40  via, for example, thermoplastic welding and/or an adhesive bonding. In an alternate embodiment, stiffener  56  may be formed integrally with outer structure  40 . 
         [0023]    In the exemplary embodiment, nacelle assembly  12  includes a structural foam  60  that is oriented and positioned to facilitate absorbing any aftward forces induced to outer surface  47  of outer structure  40 , such as may be created during a bird-strike for example. In the exemplary embodiment, structural foam  60  is coupled downstream  35  from highlight  42 , against inner surface  43  of outer structure  40  using at least one of a thermoplastic welding process and an adhesive bonding process. 
         [0024]    During operation, air flows from forward end  33  to aft end  35  of nacelle assembly  12 . Outer structure  40  defines an aerodynamic surface over outer surface  47  and facilitates maintaining laminar flow over outer surface  47  from highlight  42  to point  45  defined by maximum diameter  36 . Outer surface  47  facilitates reducing drag and improving aerodynamics and fuel efficiency. Moreover, outer structure  40  facilitates reducing assembly time and a number of components of nacelle assembly  12  as compared to known nacelle assemblies, thereby facilitating reducing manufacturing costs and improving manufacturing cycle time. The part count reduction and the use of advanced materials, such as thermoplastic or graphite, facilitate a weight reduction for nacelle assembly  12  as compared to known nacelle assemblies. 
         [0025]    The methods, apparatus, and systems described herein for an integrated inlet design are not limited to the specific embodiments described herein. The integrated inlet design described herein provides a more aerodynamic design that facilitates reducing drag and increasing fuel efficiency. Practice of the methods, apparatus, or systems described or illustrated herein is not limited to nacelle assemblies. Rather, the methods, apparatus, and systems described or illustrated herein may be utilized independently and separately from other components and/or steps described herein. 
         [0026]    The written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 
         [0027]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.