System for distributing compressed air in a combustor

Abstract

A system for distributing compressed air in a combustor of a gas turbine engine. The system may include a flow splitter, a center duct, an outer duct, and an inner duct configured to separate and receive compressed air from a prediffuser exit, and to route separate flows of the compressed air to separate downstream locations for the combustion reaction and for cooling. The system may include an axial mixer configured to axially receive a flow of the compressed air and to direct the flow to mix with fuel provided by an injector.

What is claimed is: 
     
         1 . A gas turbine engine having a center axis and comprising:
 a compressor;   a prediffuser pneumatically coupled to the compressor, the prediffuser including a prediffuser exit, an outer wall, and an inner wall; and   a system for mixing fuel and air, the system including
 a flow splitter located proximate to the prediffuser exit and configured to separate a center flow away from an outer flow and an inner flow of compressed air from the prediffuser exit, the center flow having a higher average velocity than the outer flow and the inner flow, 
 a center duct including a center duct inlet and a center duct exit, the center duct configured to pneumatically couple with a portion of the prediffuser exit offset from the outer wall and the inner wall at the center duct inlet, the center duct further configured to receive the center flow from the prediffuser exit and to route the center flow to a combustion chamber of the gas turbine engine, and 
 an axial mixer within the center duct, the axial mixer configured to direct the center flow to mix with fuel provided by an injector. 
   
     
     
         2 . The gas turbine engine of  claim 1 , wherein an effective flow area of the center duct increases between the center duct inlet and the center duct exit. 
     
     
         3 . The gas turbine engine of  claim 1 , wherein the axial mixer includes a lobe mixer, the lobe mixer having a plurality of alternating lobes circumferentially distributed around an injector axis. 
     
     
         4 . The gas turbine engine of  claim 3 , wherein an effective flow area of the center duct increases between the center duct inlet and the plurality of alternating lobes; and
 wherein the effective flow area of the center duct hold the effective flow area constant or reduces the effective flow area between the plurality of alternating lobes and the center duct exit.   
     
     
         5 . The gas turbine engine of  claim 1 , wherein the center duct is further configured to extend to and pneumatically couple with the combustion chamber of the gas turbine engine. 
     
     
         6 . The gas turbine engine of  claim 1 , wherein the axial mixer is further configured to initially mix the center flow with the fuel upon entering the combustion chamber of the gas turbine engine. 
     
     
         7 . The gas turbine engine of  claim 1 , wherein the axial mixer is further configured to direct the center flow to pre-mix with the fuel upstream of the combustion chamber of the gas turbine engine. 
     
     
         8 . The gas turbine engine of  claim 1 , wherein the flow splitter extends upstream of the prediffuser exit into the prediffuser, the flow splitter further configured to separate the center flow away from the outer flow and the inner flow while within the prediffuser. 
     
     
         9 . The gas turbine engine of  claim 1 , wherein the center duct is configured such that the center flow only includes compressed air leaving the prediffuser exit having a velocity, along a radial velocity profile, that is greater than or equal to an average velocity of all compressed air leaving the prediffuser exit, along the radial velocity profile. 
     
     
         10 . A gas turbine engine having a center axis and comprising:
 a compressor;   a prediffuser pneumatically coupled to the compressor, the prediffuser including a prediffuser exit, an outer wall, and an inner wall; and   a combustor air duct network including
 a flow splitter located proximate to the prediffuser exit and configured to separate a center flow away from an outer flow and an inner flow of compressed air from the prediffuser exit, the outer flow being radially outward and the inner flow being radially inward from the center flow, relative to the center axis; 
 a center duct including a center duct inlet and a center duct exit, the center duct configured to pneumatically couple with a portion of the prediffuser exit offset from the outer wall and the inner wall at the center duct inlet, the center duct further configured to receive the center flow from the prediffuser exit and to route the center flow to a combustion chamber of the gas turbine engine; and 
 an outer duct including an outer duct inlet and an outer duct exit, the outer duct configured to pneumatically couple with the prediffuser exit at the outer duct inlet, adjacent to the center duct inlet, the outer duct further configured to receive the outer flow of compressed air from the prediffuser and to route the outer flow to an outer side of the combustion chamber, relative to the center axis; and 
 an inner duct including an inner duct inlet and an inner duct exit, the inner duct configured to pneumatically couple with the prediffuser exit at the inner duct inlet, adjacent to the center duct inlet and opposite the outer duct inlet, the inner duct further configured to receive the inner flow of compressed air from the prediffuser and to route the inner flow to an inner side of the combustion chamber, relative to the center axis. 
   
     
     
         11 . The gas turbine engine of  claim 10 , wherein the center duct is further configured to extend to and pneumatically couple with an injector port of the combustion chamber. 
     
     
         12 . The gas turbine engine of  claim 10 , wherein a first portion of the center duct includes the center duct inlet and is configured to extend to an injector, and wherein a second portion of the center duct is integrated into the injector, the first and second portions of the center duct pneumatically coupled with each other. 
     
     
         13 . The gas turbine engine of  claim 10 , wherein the gas turbine engine has a plurality of injectors; and
 wherein the combustor air duct network includes a plurality of the center duct, each configured to interface one of the plurality of injectors.   
     
     
         14 . The gas turbine engine of  claim 10 , wherein an effective flow area of the center duct increases between the center duct inlet and the center duct exit. 
     
     
         15 . The gas turbine engine of  claim 10 , wherein the center duct is configured such that the center flow only includes compressed air leaving the prediffuser exit having a velocity, along a radial velocity profile, that is greater than or equal to an average velocity of all compressed air leaving the prediffuser exit, along the radial velocity profile. 
     
     
         16 . The gas turbine engine of  claim 10 , further comprising an intermediate duct including an intermediate duct inlet and an intermediate duct exit, the intermediate duct configured to bleed off air from the center duct via the intermediate duct inlet, the intermediate duct further configured to route the bled off air to a portion of the combustion chamber for cooling. 
     
     
         17 . The gas turbine engine of  claim 10 , further comprising an intermediate duct including an intermediate duct inlet and an intermediate duct exit, the intermediate duct configured to bleed off air from at least one of the outer duct and the inner duct, via the intermediate duct inlet, the intermediate duct further configured to route the bled off air to a portion of the combustion chamber for cooling. 
     
     
         18 . A gas turbine engine having a center axis and comprising:
 a compressor;   a combustor coupled to the compressor, the combustor including a prediffuser pneumatically coupled to the compressor, the prediffuser including a prediffuser exit, an outer wall, and an inner wall; and   a system for distributing compressed air in the combustor including
 a center duct including a center duct inlet, the center duct configured to be pneumatically coupled to the prediffuser exit at the center duct inlet and extend downstream of the prediffuser exit, the center duct further configured to receive a center flow of compressed air from the prediffuser exit, the center flow being separated away from an outer flow and an inner flow of compressed air from the prediffuser exit, the outer flow also being radially outward and the inner flow being radially inward from the center flow, relative to the center axis, the center duct further configured to route the center flow to a combustion chamber of the gas turbine engine; and 
 an outer duct including an outer duct inlet and an outer duct exit, the outer duct configured to be pneumatically coupled to the prediffuser exit at the outer duct inlet and to receive the outer flow of compressed air from the prediffuser, the outer duct further configured to route the outer flow to an outer side of the combustion chamber, relative to the center axis; and 
 an inner duct including an inner duct inlet and an inner duct exit, the inner duct configured to be pneumatically coupled to the prediffuser exit at the inner duct inlet and to receive the inner flow of compressed air from the prediffuser, the inner duct further configured to route the inner flow to an inner side of the combustion chamber, relative to the center axis. 
 an axial mixer within the center duct, the axial mixer configured to direct the center flow to mix with fuel provided by an injector. 
   
     
     
         19 . The gas turbine engine of  claim 18 , wherein the axial mixer includes a lobe mixer, the lobe mixer having a plurality of alternating lobes circumferentially distributed around an injector axis. 
     
     
         20 . The gas turbine engine of  claim 18 , further comprising an intermediate duct including an intermediate duct inlet and an intermediate duct exit, the intermediate duct configured to bleed off air from the center duct via the intermediate duct inlet, the intermediate duct further configured to route the bled off air to a portion of the combustion chamber for cooling.