Abstract:
A gas turbine engine augmentor has a centerbody within a gas flowpath from upstream to downstream. A plurality of vanes are positioned in the gas flowpath outboard of the centerbody. An augmenter fuel conduit extends through a first of the vanes to deliver fuel to the centerbody. An electrographitic carbon bushing guides and supports the augmentor fuel conduit.

Description:
U.S. GOVERNMENT RIGHTS 
   The invention was made with U.S. Government support under contract N00019-02-C-3003 awarded by the U.S. Navy. The U.S. Government has certain rights in the invention. 

   BACKGROUND OF THE INVENTION 
   This invention relates to turbine engines, and more particularly to turbine engine augmentors. 
   Afterburners or thrust augmentors are known in the industry. A number of configurations exist. In a typical configuration, exhaust gases from the turbine pass over an augmentor centerbody. Additional fuel is introduced proximate the centerbody and is combusted to provide additional thrust. In some configurations, the augmentor centerbody is integrated with the turbine centerbody. In other configurations, the augmentor centerbody is separated from the turbine centerbody with a duct surrounding an annular space between the two. U.S. Pat. Nos. 5,685,140 and 5,385,015 show exemplary integrated augmentors. 
   The centerbody may contain a burner serving as a combustion source. For introducing the additional fuel, a number of spray bars may be positioned within generally radially extending vanes. A pilot may be proximate an upstream end of the tailcone. Alternatively or additionally to the burner, a number of igniters may be positioned within associated ones of the vanes to ignite the additional fuel. Trailing portions of the vanes may serve as flameholder elements for distributing the flame across the flow path around the centerbody. 
   Separately, electro-graphitic carbon materials have been developed for a variety of uses. US Pre-grant Publication 20050084190A1 discloses a variable vane inner diameter (ID) bushing made from electro-graphitic carbon. 
   SUMMARY OF THE INVENTION 
   Accordingly, one aspect of the invention involves a turbine engine augmentor. A centerbody is positioned within a gas flowpath from upstream to downstream. A plurality of vanes are positioned in the gas flowpath outboard of the centerbody. An augmentor fuel conduit extends through a first of the vanes to deliver fuel to the centerbody. An electrographitic carbon bushing guides and supports the augmentor fuel conduit. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic longitudinal sectional view of an aircraft powerplant. 
       FIG. 2  is an aft view of an augmentor of the powerplant of  FIG. 1 . 
       FIG. 3  is a view of an outboard end of an augmentor fuel supply conduit. 
       FIG. 4  is a sectional view of the conduit of  FIG. 3 , taken along line  4 - 4 . 
   

   Like reference numbers and designations in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
     FIG. 1  shows a gas turbine engine  10  comprising, from upstream to downstream and fore to aft, a fan  11 , a compressor  12 , a combustor  14 , a turbine  16 , and an augmentor  18 . Air entering the fan  11  is divided between core gas flow  20  and bypass air flow  22 . Core gas flow  20  follows a path initially passing through the compressor  12  and subsequently through the combustor  14  and turbine  16 . Finally, the core gas flow  20  passes through the augmentor  18  where additional fuel  19  is selectively added, mixed with the flow  20 , and burned to impart more energy to the flow  20  and consequently more thrust exiting an engine nozzle  24 . Hence, core gas flow  20  may be described as following a path essentially parallel to the axis  26  of the engine  10 , through the compressor  12 , combustor  14 , turbine  16 , and augmentor  18 . Bypass air  22  also follows a path parallel to the axis  26  of the engine  10 , passing through an annulus  28  along the periphery of the engine  10  to merge with the flow  20  at or near the nozzle  24 . 
   The augmentor comprises a centerbody  30  generally symmetric around the axis  26  and formed as a portion of an engine hub. The exemplary centerbody has a main portion  32  and a tailcone  34  downstream thereof. Circumferentially arrayed vanes  36  have leading and trailing extremities  37  and  38  and extend generally radially between the centerbody  30  and a turbine exhaust case (TEC)  40 . Each of the vanes may be an assembly of a leading main body portion  42  and a trailing edge box  44 . The vanes have circumferentially opposite first and second sides  46  and  48  ( FIG. 2 ). The trailing edge box  44  may contain a spray bar (discussed below) for introducing the additional fuel  19 . The centerbody may contain a burner  50  for combusting fuel to, in turn, initiate combustion of the fuel  19 . The burner  50  and spray bars may be supplied from one or more supply conduits (not shown) extending through or along one or more of the vanes to the centerbody. As so far described, the engine configuration may be one of a number of existing engine configurations to which the present teachings may apply. However, the teachings may also apply to different engine configurations. 
     FIG. 3  shows an outboard end portion of the supply conduit  60  mounted to the TEC  40 . The conduit has an outboard end flange  62  for mating to the downstream end of an upstream supply conduit (not shown). A cylindrical body portion  64  of the conduit  60  is supported by a bushing  66 . The bushing  66  is, in turn, supported between a pair of brackets  68  and  70  mated along a mating/parting plane  72 . The brackets each have a collar/boss portion  74 ;  76  and a mounting ear  78 ;  80  extending from an outboard end of the collar/boss portion. 
   The brackets  68  and  70  have pairs of mounting ears  82 ;  84  and  86 ;  88  extending from edges of the associated collar/boss portion  74 ;  76  and meeting along the plane  72 . Each ear is secured to an opposite ear of the other bracket by a fastener (e.g., bolts/nuts  90  and  92 ). The brackets  68  and  70  are, in turn, secured to support brackets  94  and  96 , respectively, by bolts  100  and  102 . The brackets  94  and  96  are, in turn, mounted to the turbine exhaust case  40 . 
   The exemplary bushing  66  is longitudinally split along a parting plane  104  into first and second pieces  106  and  108  ( FIG. 4 ).  FIG. 4  further shows the bushing as having outboard and inboard end flanges  110  and  112  connected by a circular cylindrical tubular body  114 . In the exemplary implementation, the bushing parting plane  104  is non-coincident with the bracket parting plane  72  (e.g., off-parallel thereto). The bushing has a circular cylindrical inner surface  116  in sliding engagement with the conduit portion  64 . The lateral exterior surface  118  of the bushing body  114  may be in contact with an inboard surface  120  of the boss portions  74  and  76  of the combined brackets  68  and  70 . Engagement of the boss portions  74  and  76  with the adjacent surfaces of the flanges  110  and  112  longitudinally retains the bushing to the brackets  68  and  70 . 
     FIG. 4  further shows a central longitudinal axis  120  shared by the conduit body portion  64  and the bushing  66 . In the exemplary embodiment, the sliding engagement between the bushing and the conduit permits relative translation along the axis  120  and relative rotation about the axis  120 . In particular, vibration, and differential thermal expansion, may produce such translation and rotation of the conduit relative to the TEC  40  (and thereby relative to the brackets  68  and  70  and bushing  66 ). The axis  120  may be coincident with a local radial direction of the engine or may be slightly off-radial (e.g., to permit the conduit  60  to be appropriately oriented within the associated vane). 
   The exemplary bushing consists essentially of electro-graphitic carbon. This material is believed to have an advantageous combination of preferential wear relative to the conduit material (e.g., a nickel-based superalloy) with which the bushing interacts. In addition to wearing preferentially to mating details, the electrographitic material used for the wear members may deposit a thin layer of graphite at the wear interface. This deposition may serve to further reduce the rates of wear. Additionally, the electro-graphitic carbon has advantageous temperature stability relative to polymers and other non-metallic sacrificial wear materials used in other applications. 
   Alternative implementations may be other than monolithic electro-graphitic carbon structures. For example, the bushings may have structural cores of another material (e.g., a metal) or could have additional layers such as coatings. 
   One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.