Abstract:
A gas turbine engine has the convergent flaps and seals of an adjustable cross-sectional area nozzle connected to associated liners with a thermally compliant bracket. The bracket includes spaced feet with an intermediate notch spaced away from the liner. In this manner, a temperature gradient along the liner can be easily compensated at the connection of the bracket to the liner by adjustment within the notch. In other features, the bracket is riveted to the liner, providing further resistance to thermal expansion due to temperature gradiations.

Description:
This invention was made with government support under U.S. Navy Contract No. N00019-02-C-3003. The government therefore has certain rights in this invention. 

   BACKGROUND OF THE INVENTION 
   This application relates to a bracket for attaching liners to the convergent flaps and seals which are part of a convergent/divergent nozzle for a gas turbine engine, and wherein the brackets are more thermally compliant than in the prior art. 
   A gas turbine engine typically includes a plurality of sections, which are positioned in series. A fan section moves air downstream towards a compressor section. The compressor section compresses the air and delivers it into a combustion section. In the combustion section, air and fuel are mixed and combusted. Products of combustion pass downstream over turbines, and then outwardly through a nozzle. 
   It is known in the prior art to vary the cross-sectional area of the nozzle by having flaps that pivot inwardly and outwardly. Typically, a plurality of circumferentially spaced flaps and seals are positioned upstream of a throat, and are called the convergent flaps and seals. Downstream of the throat are divergent flaps and seals. The convergent flaps and seals not only move to define the throat area, but they also provide a block for the products of combustion reaching a housing outboard of the flaps and seals. 
   In the structure for the convergent flaps and seals, a liner typically faces the products of combustion. The liner is connected by a bracket to the flap or seal. Traditionally, the bracket has been welded to the hot liner. The bracket is then bolted to the cooler flap or seal. 
   In the prior art, the brackets have proved challenging to mount to the hot liner. In particular, the liner extends over a portion of the length of the nozzle, and as one moves downstream in the nozzle, the liner is subject to greater heat. This is true for several reasons, one being the fact that cooling air is mixed into the nozzle at a position upstream. This cooling air has lesser and lesser effects as one moves downstream. 
   At any rate, the bracket is subject to a thermal gradient along the length of its connection to the hot liner. The bracket has been welded along its entire length to the hot sheet. This provides a relatively rigid connection which is not able to adjust to thermal gradiations. In the prior art, very thermally resistant materials (having a low coefficient of thermal expansion) have been utilized for the bracket and hot plate. However, this sometimes proves to be an undesirable constraint. 
   SUMMARY OF THE INVENTION 
   In a disclosed embodiment of this invention, a bracket attaches a liner to both the convergent flaps and seals. The bracket has a footprint of attachment to the relatively hot liner that includes pairs of spaced legs. These contact surfaces between the bracket and the liner are at axially spaced locations. A notch is formed between the axially spaced legs to make the bracket more thermally compliant along the axis of the jet engine. 
   In other features of this invention, the bracket is riveted to the liner. the use of the rivet provides a further ability to adjust to any relatively thermal expansion between the upstream and downstream locations, and also allows circumferential adjustment. 
   These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of a jet engine as known in the prior art. 
       FIG. 2  shows a portion of a structure for adjusting the cross-sectional area of a nozzle. 
       FIG. 3  shows a portion of a liner attachment as known in the prior art. 
       FIG. 4  shows an improved liner attachment. 
       FIG. 5  is an exploded view of a convergent flap and seal along with the liner attachments. 
       FIG. 6  is an exploded view of the improved flap liner attachment. 
       FIG. 7  is an exploded view of the improved seal attachment. 
       FIG. 8  is an exploded view of the seal. 
       FIG. 9  is an exploded view of the flap. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a gas turbine engine  10 . As known, a fan section  11  moves air and rotates about an axial center line  12 . A compressor section  13 , a combustion section  14 , and a turbine section  15  are also centered on the axial center line  12 . A nozzle section of the turbine discharges gas downstream. A convergent section  36  leads into a throat and a divergent section  31  leads away.  FIG. 1  is a schematic view, however, it does show the main components of the gas turbine engine. 
     FIG. 2  shows a prior art structure to change a cross-sectional area of the nozzle. As known, an actuator  34  drives a piston to cause the divergent section  31  and the convergent section  36  to pivot to change the cross-sectional area of the throat between the two. This structure is shown schematically, and may be as known in the art. 
   As shown at  36 , convergent flaps and seals extend from a pivotal connection to the divergent section  31 , and upwardly to a housing  37 . This structure prevents hot gasses from an area  39  inward of the convergent section  36  from reaching a housing  41  housing the linkages and actuator  34 . As known, a liner  38  faces the hot gas, and provides some thermal protection for the flap and seals  36 . 
   As shown at  38  in  FIG. 3 , in the prior art, this liner included a plate  40 , a separate dam  42 , and rivets  44  attaching the plate  40  to an underlying plate  43 . 
   A bracket  46  includes an opening  48  to secure the liner  38  to the flap or seal. In addition, a lower surface  50  of the bracket  46  is welded at  51  to the plate  43  along its entire length. A forward portion  52  of the bracket  46  extends beyond the dam  42 . As known, the dam  42  provides a pressure differential between an upstream area forward of the dam  42 , and a downstream area adjacent to the bracket  46 . 
   As explained above, in this prior art structure, an upstream end  54  of the bracket  46  is cooler than a downstream end  56 . Thus, there is a thermal gradient along the lower surface  50  and the weld joint  51 . This causes stresses and other challenges. The prior art has addressed these challenges by forming the bracket  46  out of materials such as columbium, which have low coefficients of thermal expansion (CTE). However, recently, it has become desirable to have more freedom in the material selected for the bracket  46 . In one bracket, it is desirable to use INCO 625, which has a relatively high CTE. 
   As shown in  FIG. 4 , an inventive liner and bracket assembly  60  includes a pair of forward plates  61  and  62 . A leg  64  on the rear plate  62  extends rearwardly. Another plate  65  has a rear face  66  abutting faces  68  and  69  from the plates  61  and  62 . As shown, a rivet  70  connects the three plates. Features with regard to this structure can be best understood from co-pending patent application entitled “Axially Split Nozzle Liner for Convergent Nozzle,” filed on even date herewith and assigned Ser. No. 11/540,279, now U.S. Pat. No. 7,685,825. 
   The improved bracket  72  has spaced legs  74  and  75  along with an intermediate notch  76 . A second pair of legs  74  and  75  is on the opposed end of the bracket. That is, there are pairs of upstream and downstream legs on each circumferential side of each bracket. Rivets  78  secure the bracket  72  to the plate  65 . Due to the notch  76 , there are axially spaced legs  74  and  75 , which contact the hot plate  65 , reducing the footprint or contact area compared to the prior art. Notch  76  results in an area spaced away from the hot plate  65 . Now, when the downstream end of the bracket is subjected to greater heat than the upstream end, the spaced legs can allow some adjustment, such as by the leg  75  expanding away from the leg  74 , but with the expansion being compensated for within the notch  76 . 
   Further, the inventive bracket  72  will provide some circumferential adjusting ability also due to the rivet connection at  78 . 
   As shown in  FIG. 5 , an  38  secures the liner and bracket to an underlying convergent flap  83 . As known, an opening  184  in the flap  83  receives a bolt  86  through the opening  84  in the bracket  72 . A washer  88  and nut  90  secure the bolt. The opening  184  in the flap  83  has spring fingers  92  which serve to hold the washer  88  during assembly. Features of this structure can be best understood from the co-pending application entitled “Quick Change Fastener System for Attaching Liner Bracket to Convergent Flap and Seal in Turbine Nozzle,” filed on even date herewith, and assigned Ser. No. 11/529,836, now U.S. Pat. No. 7,617,685. The structure of the liner and bracket as shown in  FIG. 5  is the prior art structure. This view is intended to provide an understanding of how the combined liner and bracket assembly is attached to the flap or seal. However, the quick change coupling is inventive to this application. 
   A similar bracket and liner arrangement  161  has backing plate  165 , and is attached to a seal  81 , again through an arrangement similar to that shown with regard to the flap  83 . 
     FIG. 6  is an exploded view of the liner and bracket assembly  60 . As can be appreciated, the bracket  72  is positioned on the plate  65 . The rivets  70  secure the plates  61 ,  62  and  65 . An alternative rivet arrangement is disclosed in the co-pending patent application entitled “Thermally Compliant Rivet Connection for Connecting Turbine Engine Liner to Convergent Flap and Seal for Turbine Nozzle,” filed on even date herewith and assigned Ser. No. 11/540,309, now U.S. Pat. No. 7,555,904. 
   The plate  65  has a turned in end  100 .  FIG. 7  shows the similar liner and bracket assembly  261 . In general, the difference is that the plate  165  has a more complex, turned in end  166 . 
     FIG. 8  shows an exploded view of the components of the liner and bracket  261  to the convergent seals  81 .  FIG. 9  shows a similar exploded view of the components of the bracket and liner  60  being attached to the convergent flap  83 . 
   Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.