Patent Publication Number: US-2015068212-A1

Title: Combustor liner stop

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to gas turbine combustor technology generally, and more specifically, to a combustor liner stop extending radially between the combustor liner and a surrounding flow sleeve. 
     In the construction of gas turbine combustor assemblies, and particularly in can-annular combustor arrangements, a combustor liner (which encloses the combustion chamber), is surrounded by a flow sleeve providing an annular flow path therebetween. Compressor discharge air is supplied by to the annular flow path so as to provide air to the head end of the combustor liner for introduction into the combustion chamber with fuel supplied by one or more nozzles also attached to the head end of the combustor assembly. 
     In various known arrangements, a combustor liner stop is provided as part of the support assembly for the liner and also to restrict axial, angular and radial movement of the combustor liner relative to the flow sleeve. In the known arrangements, the combustor liner stop is typically located within the flow annulus between the combustor and the flow sleeve thereby creating a flow disturbance within the flow annulus. It would therefore be desirable to provide a combustor liner flow stop that reduces flow disturbances and prevents flame-holding effects in the fuel-injection area for the combustion chambers, having fuel injections upstream of the combustor head-end (so-called “quaternary fuel injection”). 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with an exemplary but nonlimiting embodiment, a combustion liner comprising a substantially cylindrical body having forward and aft ends, the forward end provided with plural, circumferentially-shaped stops adapted for connection to a flow sleeve surrounding the substantially cylindrical body, each stop comprised of a radially-projecting strut having an end remote from the substantially-cylindrical body provided with a tab having a shape different than the strut. 
     In another aspect, a combustor liner and flow sleeve assembly comprising a combustor liner having an aft end and a forward end; a flow sleeve surrounding the combustor liner and defining an axially-extending, annular flow passage radially therebetween, the flow sleeve provided with plural slots at an aft end thereof; the combustor liner provided with plural, circumferentially-spaced stops extending radially outwardly and through respective ones of the plural slots in the flow sleeve; each strut provided with a tab that lies on an exterior surface of the flow sleeve, outside the annular flow passage. 
     In still another aspect, a combustor liner and flow sleeve assembly comprising a combustor liner having an aft end and a forward end; and a flow sleeve surrounding the combustor liner and defining an axially-extending flow passage radially therebetween, the flow sleeve provided with plural slots at a forward end thereof; the combustor liner provided with plural, circumferentially-spaced airfoil-shaped struts slanted toward the aft end of the substantially-cylindrical body and extending radially outwardly and through respective ones of the plural slots in the flow sleeve; each of the plural circumferentially-spaced struts provided with a remote tab having a shape different than the strut and wherein said tab lies on an exterior surface of the flow sleeve. 
     The invention will now be described in detail in connection with the drawings identified below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified cross-section showing a combustor liner and flow sleeve assembly incorporating a liner stop in accordance with an exemplary but nonlimiting embodiment of the invention; 
         FIG. 2  is an enlarged perspective view of the liner stop shown in  FIG. 1 , but with the flow sleeve removed; 
         FIG. 3  is an end view of the combustor liner head end, showing the circumferential location of plural liner stops in accordance with the exemplary but nonlimiting embodiment of the invention; and 
         FIG. 4  is a partial perspective view of the forward end of the flow sleeve illustrating circumferentially-spaced slots which receive the liner stops shown in  FIGS. 2 and 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a combustor liner-flow sleeve assembly  10  that includes a substantially cylindrical combustor liner body (or, simply, combustor liner)  12  having a forward end  14  and an aft end  16 . The combustor liner  12  is telescopically received in, or surrounded by, a substantially cylindrical flow sleeve  18 , also having a forward end  20  and an aft end  22 . Typically, a combustor cap assembly, also referred to as a combustion head-end, (not shown) supporting a plurality of nozzles is secured to the forward end of the combustor liner. The aft ends  16 ,  22  of the combustor liner  12  and flow sleeve  18 , respectively, are typically connected to a transition piece  24  and surrounding impingement sleeve  26 . In typical can-annular combustor arrangements, compressor air enters an annular flow passage located radially between the impingement sleeve and the transition piece and flows through an axial extension of that passage (denoted as the radial passage  28 ) between the flow sleeve and the combustor liner. Air flowing through the passage  28  cools the combustor liner and is thereafter introduced into the combustion chamber  30  for mixing with the fuel supplied via the nozzles. The transition piece  24  then carries the hot combustion gases to, for example, a first stage of a gas turbine in conventional fashion. 
     The concern here is for combustor liner stops used to secure the forward end of the combustor liner to the forward end of the combustor flow sleeve, and therefore, the nozzle and transition piece/impingement sleeve configurations need not be described further. 
     In the exemplary but nonlimiting embodiment, the forward end  14  of the combustor liner  12  is provided with plural liner stops  32  ( FIGS. 1 and 2 ). Three such stops  32  are illustrated in  FIG. 3 , substantially equally spaced about the circumference of the liner  12 . It will be appreciated that the number of stops may vary but three is regarded as the minimum number needed to insure the required stability between the liner  12  and the flow sleeve  18 . 
     As best seen in  FIG. 2 , each liner stop  32  includes a strut  34  and a tab or foot  36  at the remote or free end of the strut. The strut  34  may be air-foil shaped and slanted in a radially-outward direction toward the aft end of the liner. The slanting of the strut and the airfoil shape of the strut minimize flow disruption in the air passing through the radial flow passage  28 . The tab or foot  36  has a shape different than the strut. In the exemplary embodiment, the tab  36  is shown to have a substantially rectangular block-like shape but the exact shape may vary. Preferably, the inner surface  38  is shaped to conform to the outer surface  40  of the flow sleeve  18 . 
     The forward end  20  of the flow sleeve  18  is formed with slots  40  that open to the forward end of the flow sleeve. The slots correspond in number and circumferential location to the liner stops  32 . The flow sleeve  18  is secured by sliding the flow sleeve into the combustor casing  35 . Note that the foot  36  of each strut  34  is received radially outwardly of the respective slot  40  such that the enlarged foot  36  is outside the flow sleeve  18  and thus outside the annular flow path  28 . Note also that the width of each foot  36  is wider than the respective slot  40 , preventing any radial dislodgement of the liner  12  relative to the flow sleeve  18 . After the flow sleeve and liner are fully assembled, a single or plural closure parts, for example ring  42  ( FIG. 4 ) may be bolted or otherwise suitably attached to the combustor case  35  and/or the forward end  20  of the flow sleeve  18 , closing the open forward ends of the slots  40 , and therefore precluding excessive axial displacement of the liner relative to the flow sleeve. Some space is permitted, however, for accommodating differential thermal growth of the respective liner and flow sleeve components. 
     It may also be desirable to take up some of this axial space through elastic members or elements that can be inserted into the remaining spaces in the slots  40  and that still permit axial growth but in a more controlled manner, and prevent excessive wear of the respective contact surfaces during operation. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.