Air shield for a fuel injector of a combustor

Abstract

An air shield for an injector of a combustor includes a first section that extends axially from a first end to a second end. The first section includes at least one side wall and a top wall. The at least one side wall and the top wall at least partially define a channel configured to distribute a channel airflow to the injector. The air shield also includes at least one first inlet defined through the at least one side wall and at least one second inlet defined through the top wall. The at least one first inlet and the at least one second inlet are configured to receive a portion of a surrounding airflow to at least partially form the channel airflow.

What is claimed is: 
     
         1 . An air shield for an injector of a combustor, said air shield comprising:
 a first section that extends axially from a first end to a second end, said first section comprising at least one side wall and a top wall, said at least one side wall and said top wall at least partially define a channel configured to distribute a channel airflow to the injector; and   at least one first inlet defined through said at least one side wall and at least one second inlet defined through said top wall, said at least one first inlet and said at least one second inlet are configured to receive a portion of a surrounding airflow to at least partially form the channel airflow.   
     
     
         2 . The air shield of  claim 1 , wherein said first end is configured to be disposed proximate the injector, said at least one first inlet and said at least one second inlet are located generally proximate said second end. 
     
     
         3 . The air shield of  claim 1 , wherein said first section includes a neck proximate to said second end and a pair of shoulder regions that extend from said neck, said at least one first inlet and said at least one second inlet are located on at least one of said neck and said shoulder regions. 
     
     
         4 . The air shield of  claim 1 , wherein said first section includes a neck proximate to said second end and a pair of shoulder regions that extend from said neck, said at least one first inlet comprises an opposing pair of first inlets each defined along one of said pair of shoulder regions. 
     
     
         5 . The air shield of  claim 1 , wherein said first section includes a neck proximate to said second end, said at least one second inlet comprises at least one top window defined in said top wall along said neck. 
     
     
         6 . The air shield of  claim 5 , wherein said at least one top window comprises a pair of top windows. 
     
     
         7 . The air shield of  claim 1 , wherein said first section includes a neck proximate to said second end, said at least one second inlet comprises a plurality of neck apertures defined in said top wall along said neck. 
     
     
         8 . The air shield of  claim 1 , wherein said first section includes a neck proximate to said second end and a pair of shoulder regions that extend from said neck, said at least one second inlet comprises a plurality of shoulder apertures defined in said top wall proximate said pair of shoulder regions. 
     
     
         9 . The air shield of  claim 8 , wherein at least one of a size and a position of said plurality of shoulder apertures is configured to receive a portion of the channel airflow into said channel near said shoulder regions such that a tendency of the channel airflow to separate near said shoulder regions is reduced or eliminated. 
     
     
         10 . The air shield of  claim 1 , wherein at least one of a size and a position of said at least one second inlet is configured to enhance an axial component of the channel airflow. 
     
     
         11 . A combustor for a gas turbine, said combustor comprising:
 a liner that defines a primary combustion zone;   a sleeve that substantially circumscribes said liner;   a secondary combustion zone downstream from, and in flow communication with, said first combustion zone;   an injector coupled to said sleeve upstream from said secondary combustion zone, said injector comprises at least one transfer tube in flow communication with said primary combustion zone; and   an air shield coupled to said sleeve, said air shield comprising:
 a first section that extends axially from a first end to a second end, said first section comprising at least one side wall and a top wall, said at least one side wall and said top wall at least partially define a channel configured to distribute a channel airflow to said injector; and 
 at least one first inlet defined through said at least one side wall and at least one second inlet defined through said top wall, said at least one first inlet and said at least one second inlet are configured to receive a portion of a surrounding airflow of said combustor to at least partially form the channel airflow. 
   
     
     
         12 . The combustor of  claim 11 , wherein said first end is configured to be disposed proximate said injector, said at least one first inlet and said at least one second inlet are located generally proximate said second end. 
     
     
         13 . The combustor of  claim 11 , wherein said first section includes a neck proximate to said second end and a pair of shoulder regions that extend from said neck, said at least one first inlet and said at least one second inlet are located on at least one of said neck and said shoulder regions. 
     
     
         14 . The combustor of  claim 11 , wherein said first section includes a neck proximate to said second end and a pair of shoulder regions that extend from said neck, said at least one first inlet comprises an opposing pair of first inlets each defined along one of said pair of shoulder regions. 
     
     
         15 . The combustor of  claim 11 , wherein said first section includes a neck proximate to said second end, said at least one second inlet comprises at least one top window defined in said top wall along said neck. 
     
     
         16 . The combustor of  claim 15 , wherein said at least one top window comprises a pair of top windows. 
     
     
         17 . The combustor of  claim 11 , wherein said first section includes a neck proximate to said second end, said at least one second inlet comprises a plurality of neck apertures defined in said top wall along said neck. 
     
     
         18 . The combustor of  claim 11 , wherein said first section includes a neck proximate to said second end and a pair of shoulder regions that extend from said neck, said at least one second inlet comprises a plurality of shoulder apertures defined in said top wall proximate said pair of shoulder regions. 
     
     
         19 . The combustor of  claim 18 , wherein at least one of a size and a position of said plurality of shoulder apertures is configured to receive a portion of the channel airflow into said channel near said shoulder regions such that a tendency of the channel airflow to separate near said shoulder regions is reduced or eliminated. 
     
     
         20 . The combustor of  claim 11 , wherein at least one of a size and a position of said at least one second inlet is configured to enhance an axial component of the channel airflow.