Abstract:
A method enables a gas turbine engine to be provided. The method comprises providing a ring support that includes a first radial flange, a second radial flange, and a plurality of beams that extend therebetween, within the engine, wherein at least one of the beams is tapered between the first and second radial flanges, and coupling the ring support to a backbone frame, such that the ring support extends substantially circumferentially within the engine.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   The U.S. Government has rights in this invention pursuant to Contract No. DAAE07-00-C-N086. 

   BACKGROUND OF THE INVENTION 
   This invention relates generally to gas turbine engines, more particularly to methods and apparatus for controlling engine clearance closures. 
   Known turbine engines include a compressor for compressing air which is suitably mixed with a fuel and channeled to a combustor wherein the mixture is ignited for generating hot combustion gases. The gases are channeled to at least one turbine, which extracts energy from the combustion gases for powering the compressor, as well as for producing useful work, such as propelling a vehicle. 
   To support engine casings and components within harsh engine environments, at least some known casings and components are supported by a plurality of support rings that are coupled together to form a backbone frame. The backbone frame provides structural support for components that are positioned radially inwardly from the backbone and also provides a means for an engine casing to be coupled around the engine. In addition, because the backbone frame facilitates controlling engine clearance closures defined between the engine casing and components positioned radially inwardly from the backbone frame, such backbone frames are typically designed to be as stiff as possible. 
   At least some known backbone frames used with recouperated engines, include a plurality of beams that extend between forward and aft flanges. To provide structural support and stiffness for the backbone frames, the beams are sized with a width that is substantially constant along a length of the beam, such that the width is as wide as possible, while still permitting physical passage of components and/or services therebetween. The beams are also sized with a thickness that is substantially constant along the beam length, and is limited by thermal induced stresses and component low cycle fatigue (LCF) considerations. More specifically, thicker and wider beams result in a stiffer structure, but are also more susceptible to thermally induced stresses and LCF. Alternatively, thinner and less wide beams are not as susceptible to thermally induced stresses and LCF, but may not provide the necessary stiffness to control engine clearance. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In one aspect, a method for assembling a gas turbine engine is provided. The method comprises providing a ring support that includes a first radial flange, a second radial flange, and a plurality of beams that extend therebetween, within the engine, wherein at least one of the beams is tapered between the first and second radial flanges, and coupling the ring support to a backbone frame, such that the ring support extends substantially circumferentially within the engine. 
   In another aspect of the invention, an apparatus used in a gas turbine engine is provided. The apparatus includes a first radial flange, a second radial flange that is axially spaced from the first radial flange, and a plurality of circumferentially-spaced beams that extend between the first radial flange and the second radial flange. At least one of the plurality of beams is tapered between the first and second radial flanges. 
   In a further aspect, a gas turbine engine is provided. The engine includes a backbone frame coupled within the gas turbine engine, and a ring support that is coupled to the backbone frame. The ring support includes a first radial flange, a second radial flange, and a plurality of circumferentially-spaced beams that extend between the first and second radial flanges. The plurality of beams include at least one tapered beam extending between the first and second radial flanges. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic of a gas turbine engine. 
       FIG. 2  is a cross-sectional illustration of a portion of the gas turbine engine shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of a ring support used with the gas turbine engine shown in  FIG. 2 ; and 
       FIG. 4  is an enlarged cross-sectional view of a portion of the gas turbine engine shown in FIG.  2  and taken along area  4 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a schematic illustration of a gas turbine engine  10  including a low pressure compressor  12 , a high pressure compressor  14 , and a combustor  16 . Engine  10  also includes a high pressure turbine  18  and a low pressure turbine  20 . Compressor  12  and turbine  20  are coupled by a first shaft  24 , and compressor  14  and turbine  18  are coupled by a second shaft  26 . In one embodiment, the gas turbine engine is an LV100 available from General Electric Company, Cincinnati, Ohio. 
   In operation, air flows through low pressure compressor  12  and compressed air is supplied from low pressure compressor  12  to high pressure compressor  14 . The highly compressed air is delivered to combustor  16 . Airflow from combustor  16  drives turbines  18  and  20  before exiting gas turbine engine  10 . 
     FIG. 2  is a cross-sectional illustration of a portion of gas turbine engine  10 .  FIG. 3  is a perspective view of a ring support  30  shown in FIG.  2 .  FIG. 4  is an enlarged cross-sectional view of a portion of ring support  30 . Engine  10  includes a combustor backbone frame  32  that extends circumferentially around combustor  16  to provide structural support to a combustor casing (not shown) that is coupled thereto and extends circumferentially around combustor  16 . Engine casing (not shown) is coupled to backbone frame  32  and also extends circumferentially around engine  10 . 
   Ring support  30  is coupled to combustor backbone frame  32 . Ring support  30  is annular and includes an annular upstream radial flange  34 , an annular downstream radial flange  36 , and a plurality of beams  38  that extend therebetween. In the exemplary embodiment, upstream and downstream flanges  34  and  36  are substantially circular and are substantially parallel. More specifically, flange  34  is spaced an axial distance  40  from flange  36 , wherein distance  40  defines a width for ring support  30 . 
   Upstream flange  34  includes an upstream surface  50 , a downstream surface  52 , and a body  54  that extends therebetween. Body  54  has a thickness  56  measured between surfaces  50  and  52 , and in the exemplary embodiment, body  54  is substantially planar. Flange  34  also has an inner diameter d 1  that is defined by an inner edge  56  of body  54 , and an outer diameter d 2  that is defined by an outer edge  58  of body  54 . A plurality of openings  62  extend through flange  34  between surfaces  50  and  52 . 
   Downstream flange  36  includes an upstream surface  70 , a downstream surface  72 , and a body  74  that extends therebetween. Body  74  has a thickness  76  measured between surfaces  70  and  72 , and in the exemplary embodiment, body  74  is substantially planar. Flange  74  also has an inner diameter d 3  that is defined by an inner edge  76  of body  74 , and an outer diameter d 4  that is defined by an outer edge  78  of body  74 . A plurality of openings  82  extend through flange  36  between surfaces  70  and  72 . In one embodiment, flange  34  is identical with flange  36 . Alternatively, flange  34  is not identical to flange  36 . 
   Ring support  30  is coupled within engine  10  by a plurality of fasteners  84  that extend through openings  62  and  82 . Specifically, a downstream end  86  of ring support  30  is coupled to backbone frame  40  by a plurality of fasteners  84  extending through downstream flange openings  82 . An upstream end  88  of ring support  30  is coupled to an engine frame (not shown) by a plurality of fasteners  84  extending through upstream flange openings  62 . More specifically, ring support  30  is coupled within engine  10  to extend axially between compressor  14  and turbine  18 , and provides structural support between compressor  14  and turbine  18 . 
   Beams  38  are spaced circumferentially between flanges  34  and  36 , and each beam includes an upstream end  92  extending from upstream flange  34 , a downstream end  94  extending from downstream flange  36 , and a body  96  extending between ends  92  and  94 . In the exemplary embodiment, beams  38  extend obliquely from each flange  34  and  36  such that a plurality of triangular-shaped openings  100  are defined circumferentially around ring support  30 . More specifically, in the exemplary embodiment, beams  38  each extend from an inner edge  56  and  76  of each respective flange  34  and  36 . 
   In addition, in the exemplary embodiment, a plurality of web flanges  104  extend between each beam end  92  or  94 , and a respective flange  34  and  36 . More specifically, in the exemplary embodiment, a pair of adjacent beam ends  92  or  94  extend from each web flange  104 . Flanges  104  provide additional structural support between beams  38  and each flange  34  and/or  36 . 
   Openings  100  permit passage of engine components and or engine services  110  therethrough. For example, in the exemplary embodiment, a plurality of fuel injectors  112  are extended through openings  100 . Although openings  100  are herein described and illustrated as being substantially triangular-shaped, it should be understood that the specific geometry of apertures  110  and orientation of beams  38  will vary depending on the particular configuration and application of ring support  30 . The embodiment illustrated is intended as exemplary, and is not intended to limit the geometry of struts  38  and/or openings  100 . 
   Each beam body  96  has a width W measured between a pair of circumferentially-opposite sidewalls  120 . Beam body  96  is tapered such that body width W is variable between flanges  34  and  36 . More specifically, body  96  is tapered from upstream flange  34  inwardly towards downstream flange  36  such that a width W U  of each beam upstream end  92  is wider than a width W D  of each beam downstream end  94 . Furthermore, each beam body  96  has a thickness T measured between a radially outer side  124  and a radially inner side  126  of each beam  38 . Beam body  96  is also tapered in a radial direction such that body thickness T is variable between flanges  34  and  36 . More specifically, body  96  is tapered from upstream flange  34  inwardly towards downstream flange  36  such that a thickness T U  of each beam upstream end  92  is wider than a thickness T D  of each beam downstream end  94   
   In the exemplary embodiment, ring support  30  is fabricated as an integrally-formed one piece assembly. In an alternative embodiment, ring support  30  is fabricated from a plurality of components coupled together. 
   During operation, as operating temperatures within engine  10  increase, thermal stresses may be induced to ring support  30 . More specifically, as temperatures increase, a thermal gradient is induced across ring support  30  between flanges  34  and  36 . Because beams  38  are tapered, thermal stresses induced to ring support  30  adjacent downstream flange  36  are facilitated to be reduced. More specifically, tapered beams  38  facilitate balancing and optimizing engine backbone stiffness and part life, such that that thermal low cycle fatigue (LCF) life is extended for ring support  30 . Furthermore, because beam upstream ends  92  are thicker and wider than beam downstream ends  94 , structural support is provided to ring support  30 , and a stiffness of beams  38  is facilitated to be maximized. More specifically, a stiffness of tapered beams  38  facilitates minimizing engine clearance closure caused by maneuver deflection, while increasing engine performance. 
   The above-described ring support provides a cost-effective and reliable means for controlling engine clearance closure. More specifically, the apparatus provides structural support between the compressor and turbine sections of an engine such that engine clearance closures caused by maneuver deflection are minimized. Moreover, the tapered beams within the ring support provides increased stiffness between the compressor and the turbine such that engine performance may be enhanced in a cost-effective and reliable manner. 
   An exemplary embodiment of a ring support and backbone structure are described above in detail. The apparatuses illustrated are not limited to the specific embodiments described herein, but rather, components of each may be utilized independently and separately from other components described herein. Each ring support can also be used in combination with other engine components. 
   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.