Abstract:
A method enables a gas turbine engine nozzle to be secured within an engine casing that includes an exterior surface. The method comprises the steps of forming a first opening to extend through the engine casing, inserting a nozzle lock through the first opening from the casing exterior surface, coupling the nozzle lock to a portion of the nozzle, and securing the nozzle lock to the engine casing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This application relates generally to gas turbine engines and, more particularly, to nozzle locks for gas turbine engines.  
           [0002]    Gas turbine engines typically include a compressor, a combustor, at least one turbine nozzle and a rotor assembly serially connected in flow communication. An engine casing extends around the engine from the compressor to the turbine assembly.  
           [0003]    In operation, airflow exiting the compressor is mixed with fuel and ignited within the combustor, and the resulting hot gas/air mixture is channeled through the turbine nozzles to the rotor assembly. As a result of exposure to the hot gas/air mixture, pressure loading may develop within the turbine nozzles.  
           [0004]    To facilitate reducing the effects of pressure loading to the turbine nozzle, at least some known turbine engines include a plurality of internal nozzle locks to maintain the turbine nozzles in alignment. The nozzle locks secure the turbine nozzle within the casing to facilitate retaining the nozzles in circumferential alignment. Accordingly, to install or replace the nozzle locks, the turbine casing is first removed. Such a procedure is time-consuming and costly.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    In an exemplary embodiment, a plurality of externally attachable nozzle locks for a gas turbine engine secure turbine nozzles within the engine in a cost-effective and reliable manner. Each nozzle lock includes a base, an attachment device coupled to the base, and a locking pin that extends from the base. More specifically, the locking pins extend from a respective base through the turbine casing to secure the nozzles within the turbine casing.  
           [0006]    During assembly of each nozzle lock to the gas turbine engine an opening in the turbine casing is formed, extending through the turbine casing radially outwardly from the turbine nozzle. The nozzle lock is inserted through the opening from an exterior surface of the engine casing and coupled to a portion of the nozzle. The nozzle lock is also secured to the engine casing. More specifically, the nozzle lock facilitates maintaining an alignment of the turbine nozzle despite being subjected to tangential forces induced on the turbine nozzles during engine operation. As a result, the turbine nozzle lock facilitates securing the nozzle within the engine in a cost effective and reliable manner. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a schematic cross-sectional view of a gas turbine engine;  
         [0008]    [0008]FIG. 2 is a partial cross-sectional view of a combustor used with the gas turbine engine shown in FIG. 1 and including a turbine nozzle and a turbine;  
         [0009]    [0009]FIG. 3 is a three dimensional view of a gas turbine casing assembly including the turbine nozzle assembly shown in FIG. 2 and including an externally attachable nozzle lock assembly;  
         [0010]    [0010]FIG. 4 is an enlarged view of the turbine nozzle shown in FIG. 2;  
         [0011]    [0011]FIG. 5 is a side view of the turbine nozzle lock shown in FIG. 3;  
         [0012]    [0012]FIG. 6 is a cross-sectional view of the nozzle lock shown in FIG. 5 installed on a gas turbine engine;  
         [0013]    [0013]FIG. 7 illustrates an exemplary first loading relationship between the nozzle lock shown in FIG. 5 and an attachment opening extending through the gas turbine casing shown in FIG. 3; and  
         [0014]    [0014]FIG. 8 illustrates an exemplary second loading relationship between the nozzle lock and the attachment opening shown in FIG. 7. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    [0015]FIG. 1 is a schematic view of a gas turbine engine  10  including a fan assembly  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 . A shaft  22  couples fan assembly  12  and turbine  20 . Engine  10  has an intake side  24  and an exhaust side  26 . An engine casing  28  including an exterior surface  30  extends circumferentially around engine  10 . In one embodiment, gas turbine engine  10  is a GE90 engine commercially available from General Electric Company, Cincinnati, Ohio. Engine  10  also includes a center longitudinal axis of symmetry  32  extending therethrough.  
         [0016]    In operation, air flows through fan assembly  12  and compressed air is supplied to high-pressure compressor  14 . Highly compressed air is delivered to combustor  16  where it is mixed with fuel and ignited. Hot gas/air mixture from combustor  16  propels turbines  18  and  20 , and turbine  20  rotates fan assembly  12  about axis  32 .  
         [0017]    [0017]FIG. 2 is a partial cross-sectional view of combustor  16 , including a turbine nozzle  56 , of gas turbine engine  10  shown in FIG. 1. Combustor  16  includes an annular outer liner  40 , an annular inner liner  42 , and a domed end  44  extending between outer and inner liners  40  and  42 , respectively. Outer liner  40  is spaced radially inward from a combustor casing  46  and couples to inner liner  42  to define a generally annular combustion chamber  48 .  
         [0018]    Combustor casing  46  is generally annular and extends downstream from a diffuser (not shown) positioned within domed end  44 . Outer liner  40  and, combustor casing  46  define an outer passageway  52 , and inner liner  42  and an inner combustor casing  54  define an inner passageway  58 . Inner liner  42  is spaced radially outward from inner combustor casing  54 . Outer and inner liners  40  and  42  extend to a turbine nozzle  60  disposed downstream from diffuser.  
         [0019]    An annular turbine nozzle  56  is disposed radially inward from a casing internal wall  70 . Combustor  16  is located upstream of nozzle  56 , and turbine blades  74  are located downstream from nozzle  56 . In one embodiment, engine  10  includes a plurality of nozzles  56 .  
         [0020]    Nozzle  56  includes an arcuate outer band  80  (shown in FIG. 4), an arcuate inner shroud segment  82 , and a nozzle vane  84  mounted between outer band  80  and inner shroud segment  82 . Nozzle vane  84  extends generally radially between outer band  80  and inner shroud segment  82 .  
         [0021]    [0021]FIG. 3 is a perspective view of gas turbine casing assembly  54  including turbine nozzle assembly  56 . FIG. 4 is an enlarged view of turbine nozzle  56 . FIG. 5 is a side view of a nozzle lock  130  used with turbine nozzle  56 . Outer band  80  includes a generally axially extending platform  92  including an upstream circumferential forward support flange  94  and a downstream circumferential aft rail  96 . Aft rail  96  includes a radial outer portion  102  including a slot  100  therein. Casing  28  includes a casing support channel  104 , a casing shoulder  106 , and a casing groove  108 . A turbine shroud forward rail  110  extends between aft rail  96  and casing groove  108 . In the exemplary embodiment, casing  28  also includes a first opening  120  and a second opening  124  that extend through casing  28 . More specifically, first opening  120  is radially outward of slot  100 , and a second opening  124  is adjacent and upstream from first opening  120 . Forward support flange  94  engages casing support channel  104  to radially support outer band  80 . Turbine shroud forward rail  110  radially supports aft rail  96  to casing shoulder  106  and facilitates minimizing leakage therebetween.  
         [0022]    Nozzle lock  130  includes a locking pin  132 , a base  134 , and an attachment device  136 . In one embodiment, locking pin  132  is formed unitarily with base  134 . In a further embodiment base  134  includes a first aperture (not shown) sized to receive and fixedly retain locking pin  132 . Base  134  includes a second aperture  142  for receiving attachment device  136 . In one embodiment, attachment device  136  is a blind bolt  148  including an insert  150 . In another embodiment attachment device  136  is a rivet (not shown). Nozzle lock  130  includes a seal  160 . In one embodiment, seal  160  is a metallic O-ring seal.  
         [0023]    Locking pin  132  includes a substantially cylindrical body  164  and a tip  166 . Body  164  extends substantially perpendicularly from base  134  such that tip  166  is a distance  167  from base  134 . In one embodiment nozzle lock  130  includes a plurality of locking pins  132 .  
         [0024]    [0024]FIG. 6 is a cross-sectional view of nozzle lock  130  coupled to gas turbine engine  10 . Nozzle lock  130  facilitates restricting tangential movement of nozzle  56 . Base  134  is coupled to exterior surface  30  by attachment device  136 . Seal  160  extends circumferentially around locking pin  132  to facilitate reducing or eliminating gas/air mixture leakage through exterior surface  30 .  
         [0025]    Locking pin  132  extends through opening  120  (shown in FIG. 3) to radially engage aft rail slot  100  (shown in FIG. 3) to secure nozzle  56  to casing  28 . Because nozzle  56  is secured to casing  28 , nozzle lock  130  facilitates maintaining a relative alignment of nozzle  56  within engine  10  despite nozzle  56  being subjected to tangential forces induced by the gas/air mixture. Tip  166  is adapted to engage slot  100 . In an exemplary embodiment tip  166  is cylindrical. In other embodiments a shape of tip  166  is selected to satisfy system requirements while securing nozzle  56  in slot  100 , and includes, but is not limited to a square shape, a rectangular shape, or a crescent moon shape.  
         [0026]    Attachment device  136  is coupled to base  134  and secures base  134  to casing  28 . Attachment device  136  is inserted in second opening  124  (shown in FIG. 3) to secure base  134  to casing  28 . In an alternate embodiment attachment device  136  includes a circumferential split ring (not shown) that encircles turbine engine  10  and secures base  134  to casing  28 .  
         [0027]    During operation hot gas/air mixture from combustor  16  (shown in FIG. 1) is directed through nozzle  56  to turbine blades  74  (shown in FIG. 2) to rotate the turbine rotor (not shown). The combustion gas mixture may exert axial and tangential forces on nozzle  56  as nozzle  56  redirects the gas/air mixture. Nozzle vane  84  (shown in FIG. 2) redirects the gas/air mixture to impinge on turbine blade  74  and impart a tangential force on nozzle  56 . Outer band  80  and inner shroud segment  82  (shown in FIG. 2) support and position nozzle vane  84 . Nozzle lock  130  secures outer band  80  to casing  28  and restrains tangential movement or flexing of nozzle  56 . Base  134  is mounted to casing external surface  30  and seal  160  seals casing  28 .  
         [0028]    In one embodiment, nozzle lock  130  is installed during initial assembly. In an alternate embodiment, nozzle lock  130  is installed as an engine maintenance procedure after engine assembly. In a further embodiment, nozzle lock  130  supplements internal nozzle locks already installed on an engine, and as such, nozzle lock  130  is capable of being installed with or without a removal of other engine components. Advantageously, nozzle lock  130  can be installed on an engine without disassembly of engine casing  28  or removal of engine  10  from its operating configuration, such as on an aircraft wing.  
         [0029]    In one embodiment a technician forms opening  120  in casing by drilling using standard machining techniques to maintain gas turbine cleanliness. The technician inserts locking pin  132  of nozzle lock  130  from casing exterior surface  28  through opening  120  to engage a portion of nozzle  56 . In one embodiment tip  166  engages slot  100  to secure nozzle  56  and restrict tangential movement of nozzle  56 . The technician secures nozzle lock  130  to engine casing  28 . In one embodiment the technician inserts bolt  148  through second aperture  142  (shown in FIG. 3) and into second opening  124  to secure nozzle lock  130  to casing exterior surface  28 .  
         [0030]    [0030]FIG. 7 illustrates a first loading relationship between nozzle lock  164  and engine casing opening  120  with respect to attachment aperture  142 . FIG. 8 illustrates a second loading relationship between nozzle lock  164  and engine casing opening  120  with respect to attachment aperture  142 . In the exemplary embodiment of FIG. 7, a load applied to nozzle lock body  142  adjacent to nozzle outer band  80  (shown in FIG. 4) may result in unacceptably high stresses in nozzle lock  130 , if nozzle lock cylindrical body  164  is not in direct contact with case opening  120 . More specifically, fatigue failure of nozzle lock  130  may result from such loading. However, if nozzle lock cylindrical body  164  is in contact with case opening  120  stresses induced to nozzle lock  130  are facilitated to be reduced. Unfortunately, due to necessary manufacturing tolerances, the above-described contact may not always be guaranteed.  
         [0031]    In the exemplary embodiment of FIG. 8, a single attachment aperture  142  is formed in engine casing  28  with a position offset from the direction of load application. The resulting moment about aperture  142  may result in a slight physical rotation of nozzle lock assembly  130  until contact is made between nozzle lock cylindrical body  164  and case opening  120 , as shown in FIG. 8. This type of stress reducing, self-adjusting capability is possible because of two conditions that are present in this invention. More specifically, a first condition is that the attachment is statically unstable once clamping friction at aperture  142  is exceeded. The second such condition is that relative position of aperture  142  is not along a line of action of load application, thus resulting in a moment about aperture  142  and subsequent rotation.  
         [0032]    The above-described nozzle lock for a gas turbine engine is cost-effective and reliable. The nozzle lock secures the nozzle to the casing, thus facilitating maintaining the nozzles in alignment within the engine. Furthermore, because the nozzles are secured in alignment, the nozzle lock also facilitates reducing the effects of tangential forces induced to the nozzles during engine operation. In addition, because the nozzle lock may be installed or removed from the engine without removing the engine casing, the nozzle lock also facilitates in-place engine maintenance. Furthermore, the nozzle locks facilitate the nozzles self-aligning with respect to the load path during operation. As a result, the nozzle lock facilitates maintaining the nozzle in alignment in a cost-effective and reliable manner.  
         [0033]    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.