Patent Publication Number: US-2013234396-A1

Title: Transition Piece Aft-Frame Seals

Description:
FIELD OF THE DISCLOSURE 
     Embodiments of the present application relate generally to gas turbine engines and more particularly to combustor assemblies including transition piece aft-frame seals. 
     BACKGROUND OF THE DISCLOSURE 
     In a conventional gas turbine, numerous combustors are disposed in an annular array about the axis of the machine. A compressor supplies compressed air to each combustor, wherein the compressed air and fuel are mixed and burned. Hot combustion gases may flow from each combustor through a transition piece to a first stage nozzle to drive the turbine and generate power. An aft-frame is typically attached to the downstream or aft end of the transition piece and generally includes a sealing element to prevent leakage of the hot gases at the interface between the transition piece and the first stage nozzle. 
     The aft end between adjacent transition piece aft-frames typically creates a low pressure region in which hot, low velocity gas may accumulate. This hot gas recirculation zone may lead to degraded aft-frame life through hardware cracking and oxidation. 
     BRIEF DESCRIPTION OF THE DISCLOSURE 
     Some or all of the above needs and/or problems may be addressed by certain embodiments of the present application. According to one embodiment, there is disclosed a transition piece aft-frame seal assembly. The seal assembly may include an elongate body including a first side and a second side, at least one feed hole disposed on the first side of the body, at least one passageway extending through the body from the first side to the second side and in communication with the at least one feed hole, and at least one cooling hole disposed at the second side of the body and in communication with the at least one passageway. A flow of cooling fluid may enter the at least one feed hole, the at least one passageway, and the at least one cooling hole, wherein the at least one cooling hole directs the flow of cooling fluid to a recirculation zone about adjacent transition piece aft-frame assemblies. 
     According to another embodiment, there is disclosed a transition piece aft-frame seal assembly. The seal assembly may include a platform, a generally Y-shaped member extending from the platform, at least one feed hole disposed in the platform, at least one passageway extending from the at least one feed hole through the generally Y-shaped member, and at least one cooling hole disposed at a distal end of the generally Y-shaped member and in communication with the at least one passageway. A flow of cooling fluid may enter the at least one feed hole, the at least one passageway, and the at least one cooling hole, wherein the at least one cooling hole directs the flow of cooling fluid to a recirculation zone about adjacent transition piece aft-frame assemblies. 
     Further, according to another embodiment, there is disclosed a method. The method may include positioning a seal between adjacent transition piece aft-frame assemblies. The method may also include directing a flow of cooling fluid through the seal to a recirculation zone about the adjacent transition piece aft-frame assemblies. 
     Other embodiments, aspects, and features of the invention will become apparent to those skilled in the art from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is a schematic of an example diagram of a gas turbine engine with a compressor, a combustor, and a turbine. 
         FIG. 2  is a cross-sectional view of a portion of a combustor assembly. 
         FIG. 3  is a perspective view of an example embodiment of a seal assembly, according to an embodiment. 
         FIG. 4  is a cross-sectional view of an example embodiment of a seal assembly, according to an embodiment. 
         FIG. 5  is a cross-sectional view of an example embodiment of a seal assembly, according to an embodiment. 
         FIG. 6  is a cross-sectional view of an example embodiment of a seal assembly, according to an embodiment. 
         FIG. 7  is an example flow diagram of a method, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Illustrative embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments are shown. The present application may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like numbers refer to like elements throughout. 
     Illustrative embodiments are directed to, among other things, a combustor assembly including a trapped vortex cavity.  FIG. 1  shows a schematic view of a gas turbine engine  10  as may be used herein. As is known, the gas turbine engine  10  may include a compressor  15 . The compressor  15  compresses an incoming flow of air  20 . The compressor  15  delivers the compressed flow of air  20  to a combustor  25 . The combustor  25  mixes the compressed flow of air  20  with a pressurized flow of fuel  30  and ignites the mixture to create a flow of combustion gases  35 . Although only a single combustor  25  is shown, the gas turbine engine  10  may include any number of combustors  25 . The flow of combustion gases  35  is in turn delivered to a turbine  40 . The flow of combustion gases  35  drives the turbine  40  so as to produce mechanical work. The mechanical work produced in the turbine  40  drives the compressor  15  via a shaft  45  and an external load  50  such as an electrical generator and the like. 
     The gas turbine engine  10  may use natural gas, various types of syngas, and/or other types of fuels. The gas turbine engine  10  may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a 7 or a 9 series heavy duty gas turbine engine and the like. The gas turbine engine  10  may have different configurations and may use other types of components. 
     Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together. 
     A cross-sectional view of a combustion system  55  is illustrated, for example, in  FIG. 2 . Components of the system  55  may include a transition piece  60  for enclosing and confining combustion products for flow from a combustor  65  of a gas turbine to a first stage nozzle  70 . It should be appreciated that there may be an annular array of combustors for generating and flowing hot gases to an annular array of nozzles  70 , one of each of such combustors  65 , nozzles  70 , and transition pieces  60  being illustrated. Also illustrated is a portion of the compressor discharge casing  75 . Compressor discharge air is typically provided within the space between the casing  75  and the combustor liner  80  and transition piece  60  to cool combustion system components and as a source of dilution air. 
     As shown in  FIG. 2 , the transition piece  60  may include an enclosure  85  for confining and directing the flow of combustion products from the combustor  65  to the nozzle  70 . Thus, the enclosure  85  includes a forward end  90  and an aft end  95  for respectively receiving the combustion products and flowing the combustion products in the direction of the nozzle  70 . The forward end  90  of the transition piece  60  may be generally circular. In one embodiment, the transition piece  60  may transition from a circular forward end  90  generally axially and radially inwardly relative to the turbine axis and terminates in a slightly arcuate, generally rectilinear aft end  95 . Located between the aft end  95  and the nozzle  70  is a typical aft-frame  100 . The aft-frame  100  may be generally rectilinear in shape to match the shape of the aft end  95  of the transition piece  60  and may be typically attached to the transition piece  60  by welding the aft-frame  100  to the aft end  95 . 
     As is generally understood in the art, the area between two adjacent transition piece aft-frames creates a low pressure region in which hot, low velocity gas may accumulate. This hot gas recirculation zone may lead to degraded aft-frame life through hardware cracking and oxidation. In certain embodiments, the present application provides a seal between adjacent transition piece aft-frames. The seal directs cooling air into the recirculation region and expels hot gas and/or reduces the bulk temperature. The seal may increase the life of the transition piece and decrease the amount of rework required at inspection and repair intervals. 
       FIGS. 3 and 4  depict an example embodiment of a transition piece aft-frame seal assembly  102 . The seal assembly  102  may include a platform  104 . The seal assembly  102  may also include a generally Y-shaped member  106  extending from the platform  104 . A number of feed holes  108  may be disposed in the platform  104 . The feed holes  108  may be in communication with a respective passageway  110  that extends from the feed holes  108  through the generally Y-shaped member  106 . The seal assembly  102  may also include a number of cooling holes  112  disposed at a distal end of the generally Y-shaped member  106 . The cooling holes  112  may be in communication with a respective passageway  110 . 
     As depicted in  FIG. 5 , the seal assembly  102  may be disposed between adjacent transition piece aft-frame assemblies  100 . Specifically, the platform  104  may extend between the adjacent transition piece aft-frame assemblies  100  to form a seal. In certain aspects, a flow of cooling fluid  116  may pass between the adjacent transition piece aft-frame assemblies  100  and enter the feed holes  108  of the seal assembly  102 . The flow of cooling fluid  116  may pass through the passageway  110  and exit the cooling holes  112 . The cooling holes  112  may be angled to direct the flow of cooling fluid  116  to a recirculation zone  118  about an aft end  114  of the adjacent transition piece aft frame assemblies  100 . For example, the cooling holes  112  may be angled to direct the flow of cooling fluid  116  to the recirculation zone  118  to expel hot gases that accumulate in the recirculation zone  118 . 
     The angle of the cooling holes  112  may be dictated by the configuration of the seal assembly  102 . For example, as depicted in  FIG. 5 , the generally Y-shaped member  106  angles the cooling holes  112  about 40 degrees with respect to the aft end  114  of the adjacent transition piece aft frame assemblies  100 . One will appreciate, however, that the angle of the cooling holes  112  may be greater than, equal to, or less than 40 degrees depending on the configuration of the gas turbine and the recirculation zone  118 . In fact, the cooling holes  112  may be any angle. The angle of the cooling holes  112  facilitates the expulsion of hot gases that accumulate in the recirculation zone  118 . 
     Still referring to  FIG. 5 , the platform  104 , the generally Y-shaped member  106 , the feed holes  108 , the passageways  110 , and the cooling holes  112  may include a single machined piece. In another embodiment, as depicted in  FIG. 6 , the platform  104 , the generally Y-shaped member  106 , the feed holes  108 , the passageways  110 , and the cooling holes  112  may include a single formed piece. One will appreciate, however, that the seal assembly  102  may include a variety of shapes and sizes. For example, the seal assembly  102  may be any configuration that directs the flow of cooling fluid  116  to the recirculation zone  118  to expel hot gases that accumulate in the recirculation zone  118 . Any number of feed holes  108 , passageways  110 , and cooling holes  112  may be included to expel hot gases that accumulate in the recirculation zone  118 . 
       FIG. 7  illustrates an example flow diagram of a method  700  for directing a flow of cooling fluid to a recirculation zone about an aft end of the adjacent transition piece aft frame assemblies  114 . In this particular embodiment, the method  700  may begin at block  702  of  FIG. 7  in which the method  700  may include positioning a seal between adjacent transition piece aft-frame assemblies. At block  704 , the method may include directing a flow of cooling fluid through the seal to a recirculation zone about the adjacent transition piece aft-frame assemblies. Moreover, at block  706 , the method  700  may include angling the flow of cooling fluid to direct the flow of cooling fluid about an aft face of adjacent transition piece aft frame assemblies about the recirculation zone to expel hot gases that accumulate in the recirculation zone. 
     Although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments.