Abstract:
Aspects of the present invention relate to systems and methods of a vane design utilizing welding techniques. The present invention concerns a method for preventing cracking within a vane assembly utilizing full penetration welding. Additional embodiments concern a vane design that, when assembled with another vane, comprises an axial slot that prevents cracking within a vane assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 61/793,809, filed on Mar. 15, 2013. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention generally relates to a compressor vane assembly and more specifically to methods and systems for welding compressor vanes so as to reduce the occurrence of cracks. 
       BACKGROUND OF THE INVENTION 
       [0003]    Compressor components having an airfoil, such as a compressor blade, are held within a rotating disk or shaft and are designed to rotate at a high rate of speed in order to compress a fluid passing through, such as air. A compressor typically comprises a plurality of stages, or rotating disks of blades, of diminishing diameter that raise the pressure and temperature, of the working fluid at each stage to a pre-determined level at the compressor exit. 
         [0004]    Axial compressors having multiple stages are commonly used in gas turbine engines for increasing the pressure and temperature of air to a pre-determined level at which point fuel can be mixed with air and the mixture ignited. The hot combustion gases then pass through a turbine to provide either a propulsive output or mechanical output. 
         [0005]    A series of vanes may be welded together to form a vane assembly. However, typical welding techniques and vane designs have permitted cracks to permeate through the welds and airfoils. Cracking may impact the integrity of the vane assembly and thus, the turbine engine. 
       SUMMARY 
       [0006]    In accordance with the present invention, there is provided a novel and improved system and method for welding a vane assembly. An embodiment of the present invention provides a vane assembly for use in a welded vane assembly. An alternate embodiment of the present invention concerns a welded vane assembly configured to prevent cracking in the welds of the vane assembly. In yet another embodiment of the present invention, a method of preventing cracking within a vane assembly utilizing an improved welding joint. 
         [0007]    In an embodiment of the present invention, a vane assembly for use in a welded vane assembly is disclosed. The vane assembly comprises an inner shroud having first and second inner sidewalls with the first and second inner sidewalls each having an inner groove. The vane assembly has an airfoil extending from the inner gas path surface of the inner shroud to an outer gas path surface of an outer shroud. The outer shroud has opposing first and second outer sidewalls, where each outer sidewall has a groove. The inner and outer grooves are positioned a distance through the radial thickness of the inner and outer sidewalls. 
         [0008]    In an alternate embodiment of the present invention, a welded vane assembly is disclosed comprising a first and second vane assembly which are welded together along a joint formed between adjacent inner and outer sidewalls. A full penetration weld is achieved along the joint due to an inner and outer channel being formed through grooves in the inner and outer sidewalls of adjacent vanes. Each of the first and second vane assembly has an inner shroud having first and second inner sidewalls with the first and second inner sidewalls each having an inner groove. The vane assembly has an airfoil extending from the inner gas path surface of the inner shroud to an outer gas path surface of an outer shroud. The outer shroud has opposing first and second outer sidewalls, where each outer sidewall has a groove. The inner and outer grooves are positioned a distance through the radial thickness of the inner and outer sidewalls. 
         [0009]    In yet another embodiment of the present invention, a method of reducing cracks in a welded vane assembly is disclosed. The method comprises the steps of providing first and second vane assemblies, each having an inner shroud with first and second inner sidewalls with the first and second inner sidewalls each having an inner groove. The vane assembly has an airfoil extending from the inner gas path surface of the inner shroud to an outer gas path surface of an outer shroud. The outer shroud has opposing first and second outer sidewalls, where each outer sidewall has a groove. The inner and outer grooves are positioned a distance through the radial thickness of the inner and outer sidewalls. The first vane assembly is positioned adjacent the second vane assembly such that the respective inner sidewalls and outer sidewalls are positioned adjacent to each other such that the first vane assembly is secured to the second vane assembly along an interface region of each of the first and second inner and outer shrouds. 
         [0010]    Additional advantages and features of the present invention will be set forth in part in a description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from practice of the invention. The instant invention will now be described with particular reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]    The present invention is described in detail below with reference to the attached drawing figures, wherein: 
           [0012]      FIG. 1A  is a perspective view of a vane in accordance with an embodiment of the present invention; 
           [0013]      FIG. 1B  is an alternate perspective view in accordance with an embodiment of the present invention; 
           [0014]      FIG. 1C  is an elevation view in accordance with an embodiment of the present invention; 
           [0015]      FIG. 1D  is an opposing elevation view of the vane of  FIG. 1C  in accordance with an embodiment of the present invention; 
           [0016]      FIG. 2  is a perspective view of a vane assembly in accordance with an embodiment of the present invention; 
           [0017]      FIG. 3  is an alternate perspective view of the vane assembly of  FIG. 2  in accordance with an embodiment of the present invention; 
           [0018]      FIG. 4  is an alternate perspective view of the vane assembly of  FIG. 2  in accordance with an embodiment of the present invention; and, 
           [0019]      FIG. 5  is a detailed perspective view of a portion of the vane assembly of  FIG. 2  in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The subject matter of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different components, combinations of components, steps, or combinations of steps similar to the ones described in this document, in conjunction with other present or future technologies. 
         [0021]    The present invention is described in detail in relation to  FIG. 1A-FIG .  5  and can be applied to a variety of vane and vane assemblies. Referring initially to  FIG. 1A-1D  a vane assembly  100  includes an inner shroud  110  having an inner gas path surface  112  which defines a portion of the inner flow path wall at a particular location within an engine. An airfoil  130  extends radially outward from inner gas path surface  112  of the inner shroud  110  from a root  132  toward a tip  134 . The airfoil  130  is attached to the inner shroud  110  proximate the root  132  of the airfoil  130 . The airfoil  130  can be integrally formed with the inner shroud  110  through a casting or forging process or the like, or alternatively, may be mechanically joined via welding, brazing or by any other joining method known to those skilled in the art. An outer shroud  120  can be attached to the airfoil  130  proximate the tip  134 . The outer shroud  120  includes an outer gas path surface  122  which may form a portion of the outer flow path in a turbine section of an engine. 
         [0022]    The vane assembly  100  also comprises a plurality of grooves  140 ,  142 ,  144 , and  146 . A first inner groove  140  is located along a first inner sidewall  160  of inner shroud  110 . In some embodiments, a length of groove  140  runs along the entire length of the first inner sidewall  160  of inner shroud  110 . In other embodiments, the groove  140  may extend approximately between 25% and 75% of the length of the first inner sidewall  160  of the inner shroud  110 . A second inner groove  142  is located on a second inner sidewall side  164  opposite of the first inner sidewall  160  of the shroud  110 . Similar to the first inner groove  140 , the second inner groove  142  may comprise a length equal to a length of the second inner sidewall  164  or length between 25% and 75% of the length of the second inner sidewall  164  of shroud  110 . First outer groove  144  is located along a first outer sidewall  162  of the outer shroud  120 . A length of the first outer groove  144  may comprise a length equal to a length of the first outer sidewall  162  or extend approximately 25%-75% of the length of the first outer sidewall  162  of the outer shroud  120 . Second outer groove  146  is located along a second outer sidewall  166  (not shown) of the outer shroud  120 . A length of the second outer groove  146  may comprise a length equal to a length of the second outer sidewall  166  or extend approximately 25%-75% of the length of the second outer sidewall  166  of the outer shroud  120 . Outer sidewalls  162  and  166  may mirror the inner sidewalls  160  and  164 , respectively. 
         [0023]    An alternate embodiment of the present invention is depicted in  FIGS. 2-5 , where a welded vane assembly is depicted. In embodiments of the present invention, full penetration welding may be used to weld a first vane assembly to a second vane assembly. Full penetration welding involves consuming a portion of the inner shroud  110  and/or outer shroud  120 , to be welded to a portion of a corresponding inner or outer shroud of an adjacent vane. Embodiments of the present invention may also utilize partial penetration welding in combination with features of vane assembly  100  to prevent cracking within the vane assembly. 
         [0024]    Referring to  FIG. 2 , a welded vane assembly  200  comprising a first vane assembly  205  and a second vane assembly  305 , where the first vane assembly  205  is secured to the second vane assembly  305 . The first vane assembly  205  and second vane assembly  305  are each similar to the vane assembly  100  of  FIGS. 1A-1D . More specifically, the first vane assembly  205  includes an inner shroud  210  having an inner gas path surface  212  which defines a portion of the inner flow path wall at a particular location within an engine. A first airfoil  230  extends radially outward from inner gas path surface  212  of the inner shroud  210  from a root  232  toward a tip  234 . The first airfoil  230  is attached to the inner shroud  210  proximate the root  232  of the first airfoil  230 . The first airfoil  230  can be integrally formed with the inner shroud  210  through a casting or forging process or the like, or alternatively may be mechanically joined via welding, brazing or by any other joining method known to those skilled in the art. An outer shroud  220  can be attached to the airfoil  230  proximate the tip  234 . The outer shroud  220  includes an outer gas path surface  222  which may form a portion of the outer flow path in a turbine section of an engine. 
         [0025]    The first vane assembly  205  also comprises a plurality of grooves  240 ,  242 ,  244 , and  246 , some of which may be visible in  FIGS. 3-5 , but others of which may not be clear, but are understood to be similar to features of the vane assembly of  FIGS. 1A-1D . A first inner groove  240  is located along a first inner sidewall  260  of inner shroud  210 . In some embodiments, a length of groove  240  runs along the entire length of the first inner sidewall  260  of inner shroud  210 , but can also extend a shorter distance, approximately between 25% and 75% of the length of the first inner sidewall  260  of the inner shroud  210 . A second inner groove  242  is located on a second inner sidewall side  264  opposite of the first inner sidewall  260  of the shroud  210 . Similar to the first inner groove  240 , the second inner groove  242  may comprise a length equal to a length of the second inner sidewall  264  or length between 25% and 75% of the length of the second inner sidewall  264  of shroud  210 . First outer groove  244  is located along a first outer sidewall  262  of the outer shroud  220 , while a second outer groove  246  is located along a second outer sidewall  266 . The length of the first outer groove  244  and second outer groove  246  may comprise a length equal to a length of the first outer sidewall  262  and second outer sidewall  266 , respectively. Alternatively, the first and second outer grooves  244  and  246  can extend approximately 25%-75% of the length of the first outer sidewall  262  or second outer sidewall  266  of the outer shroud  220 . Outer sidewalls  264  and  266  may mirror the inner sidewalls  260  and  262 , respectively. 
         [0026]    The second vane assembly  305  is also depicted in  FIGS. 2-4 . The second vane assembly  305  is a vane generally similar to that of the first vane assembly  205 . More specifically, the second vane assembly  305  of the welded vane assembly  200  comprises an inner shroud  310  having an inner gas path surface  312  which defines a portion of the inner flow path wall at a particular location within an engine. A second airfoil  330  extends radially outward from inner gas path surface  312  of the inner shroud  310  from a root  332  toward a tip  334 . The second airfoil  330  is attached to the inner shroud  310  proximate the root  332  of the second airfoil  330 . The second airfoil  330  can be integrally formed with the inner shroud  310  through a casting or forging process or the like, or alternatively may be mechanically joined via welding, brazing or by any other joining method known to those skilled in the art. An outer shroud  320  can be attached to the airfoil  330  proximate the tip  334 . The outer shroud  320  includes an outer gas path surface  322  which may form a portion of the outer flow path in a turbine section of an engine. 
         [0027]    The second vane assembly  305  also comprises a plurality of grooves  340 ,  342 ,  344 , and  346 , some of which may be visible in  FIG. 2 , but others of which may not be clear, but are understood to be similar to features of the vane assembly of  FIG. 1 . A first inner groove  340  is located along a first inner sidewall  360  of inner shroud  310 . In some embodiments, a length of groove  340  runs along the entire length of the first inner sidewall  360  of inner shroud  310 , but can also extend a shorter distance, approximately between 25% and 75% of the length of the first inner sidewall  360  of the inner shroud  310 . A second inner groove  342  is located on a second inner sidewall side  364  opposite of the first inner sidewall  360  of the shroud  310 . Similar to the first inner groove  340 , the second inner groove  342  may comprise a length equal to a length of the second inner sidewall  364  or length between 25% and 75% of the length of the second inner sidewall  364  of shroud  310 . First outer groove  344  is located along a first outer sidewall  362  of the outer shroud  320 , while a second outer groove  346  is located along a second outer sidewall  366 . The length of the first outer groove  344  and second outer groove  346  may comprise a length equal to a length of the first outer sidewall  362  and second outer sidewall  366 , respectively. Alternatively, the first and second outer grooves  344  and  346  can extend approximately 25%-75% of the length of the first outer sidewall  362  or second outer sidewall  366  of the outer shroud  320 . Outer sidewalls  364  and  366  may minor the inner sidewalls  360  and  362 , respectively. 
         [0028]    In the welded vane assembly  300  depicted in  FIGS. 2-5 , the first and second vane assemblies  205  and  305 , respectively, are aligned at their inner shrouds  210  and  310  and outer shrouds  220  and  320 . More specifically, as it can be seen from  FIGS. 3 and 4 , which are top and bottom perspective views of the vane assembly  200 , with the shrouds  210  and  310  aligned as shown in  FIG. 3 . A weld is placed along the shroud joint  410 , securing the shroud  210  of the first vane assembly  205  to the shroud  310  of the second vane assembly  305 . The weld penetrates a portion of the thickness of the shrouds  210  and  310  until the channel  370  is reached. The welded vane assembly  200  comprises an inner channel  370  formed when the first inner groove  240  of the first inner sidewall  260  aligns with the second inner groove  342  in the second inner sidewall  364  of the second vane assembly  305 . The weld extends the length L1 of the inner shroud joint  410  and can be performed by TIG, electron beam or other acceptable welding technique. 
         [0029]    The welded vane assembly  200  also comprises a welded joint  420  at the intersection of the first outer shroud  220  and the second outer shroud  320 , as shown in  FIG. 4 . The weld is placed along the joint, through at least a portion of the thickness of the shrouds  220  and  320 , such that the weld penetrates to the channel  390 , where the channel  390  is formed by grooves  244  in the first outer sidewall  262  and a groove  346  in the second outer sidewall  366 . As with the shroud joint  410 , the joint extends the length L2 of the outer shrouds. 
         [0030]    As it can be seen by  FIG. 2 , the channels  370  and  390  have a generally “racetrack” or overall cross sectional shape. This shape is a result of the shape of the grooves  240  and  342  which form channel  370  and the grooves  244  and  346  which form the channel  390 . Alternatively, the channels  370  and  390  can have a circular cross section, or any other desired cross-sectional shape. 
         [0031]    In an embodiment of the present invention, a method of reducing cracks in a welded vane assembly is disclosed. A first vane assembly and second vane assembly, as discussed above are provided. The first vane assembly  205  is positioned adjacent the second vane assembly such that the first inner sidewall of the first vane assembly contacts the second inner sidewall of the second vane assembly and a first outer sidewall of the first vane assembly contacts the second outer sidewall of the second vane assembly. The first vane assembly is then secured to the second vane assembly along an interface region (joint between adjacent vanes). The first vane assembly and second vane assembly are joined together by a full penetration weld. 
         [0032]    The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments and required operations will become apparent to those of ordinary skill in the art to which the present invention pertains without departing from its scope. 
         [0033]    From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and within the scope of the claims.