Two-branch mixing passage and method to control combustor pulsations

Abstract

A gas turbine engine combustion system including a mixing duct that separates into at least two branch passages for the delivery of a fuel and working fluid to distinct locations within a combustion chamber. The residence time for the fuel and working fluid within each of the two branch passages is distinct.

1 . A method comprising: 
 increasing the pressure of a working fluid within a compressor of a gas turbine engine;    introducing a fuel into the working fluid after said increasing to define a fuel and working fluid mixture;    separating the fuel and working fluid mixture into at least two distinct and separate fuel and working fluid mixture streams; and    delivering one of the at least two distinct and separate fuel and working fluid mixture streams to a first location within a combustion chamber and another of the at least two distinct and separate fuel and working fluid mixture streams to a second location within the combustion chamber, wherein the time to deliver the fuel and working fluid mixture stream to the first location is different than the time to deliver the fuel and working fluid mixture stream to the second location.    
   
   
       2 . The method of  claim 1 , wherein in said delivering each of the at least two distinct and separate fuel and working fluid mixture streams are accelerated until reaching the combustion chamber.  
   
   
       3 . The method of  claim 1 , wherein the difference in time to deliver the fuel and working fluid mixture streams to the combustion chamber diminishes the occurrence of fuel-air ratio fluctuations within the combustion chamber.  
   
   
       4 . The method of  claim 1 , wherein in said delivering each of the fuel and working fluid mixture streams are introduced into the combustion chamber as a plurality of jets.  
   
   
       5 . The method of  claim 1 , wherein in said introducing the fuel is discharged from a single fueling device.  
   
   
       6 . The method of  claim 1 , wherein in said delivering each of the at least two distinct and separate fuel and working fluid mixture streams are accelerated until reaching the combustion chamber; 
 wherein the difference in time to deliver the fuel and working fluid mixture streams to the combustion chamber diminishes the occurrence of fuel-air ratio fluctuations within the combustion chamber;    wherein in said delivering each of the fuel and working fluid mixture streams are introduced into the combustion chamber as a plurality of jets.    
   
   
       7 . A gas turbine engine combustor, comprising: 
 a combustion chamber;    a duct having a working fluid therein;    a fuel delivery device in fluid communication with said duct, said fuel delivery device introduces a fuel to the working fluid within said duct to define a fuel and working fluid mixture;    a first branch duct routing a first portion of the fuel and working fluid mixture from said duct to a first location at said combustion chamber;    a second branch duct routing a second portion of the fuel and working fluid mixture from said duct to a second location at said combustion chamber; and    wherein the travel time of the first portion of the fuel and working fluid mixture to said first location is different from the travel time of the second portion of the fuel and working fluid mixture to said second location.    
   
   
       8 . The combustor of  claim 7 , wherein said duct forming an annular fluid flow passage, and wherein each of said branch ducts forming an annular fluid flow passage.  
   
   
       9 . The combustor of  claim 7 , wherein each of said branches are formed to accelerate the respective portions of the fuel and working fluid mixture therethrough.  
   
   
       10 . The combustor of  claim 7 , wherein each of said branch ducts includes an exit, and wherein said exit is divided into a plurality of spaced openings.  
   
   
       11 . The combustor of  claim 7 , wherein said fuel delivery device is a fuel injecting device, and wherein all the fuel introduced into the working fluid within said duct is from said fuel injecting device.  
   
   
       12 . The combustor of  claim 7 , wherein the difference in travel time of the first portion and the second portion enables a phasing relationship which minimizes fuel-air ratio fluctuations within the combustion chamber.  
   
   
       13 . The combustor of  claim 7 , wherein said first branch duct having a first outlet and said second branch duct having a second outlet, and wherein one outlet is downstream of the other outlet.  
   
   
       14 . The combustor of  claim 7 , wherein said duct forming an annular fluid flow passage; 
 wherein each of said branch ducts forming an annular fluid flow passage;    wherein each of said branches are formed to accelerate the respective portions of the fuel and working fluid mixture therethrough;    wherein each of said branch ducts includes an exit, and wherein each of said exits is divided into a plurality of circumferentially spaced openings;    wherein the difference in travel time of the first portion and the second portion enables a phasing relationship which minimizes fuel-air ratio fluctuations within the combustion chamber; and    wherein said first branch duct having a first outlet and said second branch duct having a second outlet, and wherein one outlet is downstream of the other outlet.    
   
   
       15 . A gas turbine engine combustor for burning a fuel and air mixture, comprising: 
 a combustion chamber;    a first mixing duct;    a first fuel delivery device in fluid communication with said first mixing duct, said first fuel delivery device introduces fuel to the air within said first mixing duct to define a first fuel and air mixture;    a second mixing duct with working fluid therein, said second mixing duct forming an annular passage around at least a portion of said combustion chamber;    a second fuel delivery device in fluid communication with said second mixing duct, said second fuel delivery device introduces fuel to the air within said second mixing duct to define a second fuel and air mixture;    a first branch duct in flow communication with said second mixing duct, said first branch duct receiving and routing a portion of the second fuel and air mixture to a first location at said combustion chamber;    a second branch duct in flow communication with said second mixing duct, said second branch duct receiving and routing another portion of the second fuel and air mixture to a second location at said combustion chamber, said second location is spaced downstream from said first location; and    wherein the residence time of the portion of the second fuel and air mixture within said first branch duct is not equal to the residence time of the another portion of the second fuel and air mixture within said second branch duct.    
   
   
       16 . The combustor of  claim 15 , which further includes a plurality of swirler vanes in fluid flow communication with said first mixing duct; 
 wherein said second mixing duct forms an annular fluid flow passage; and    wherein said branch ducts each include an outlet, and wherein each branch duct is configured to accelerate the fuel and air mixture passing to the respective outlet.    
   
   
       17 . The combustor of  claim 16 , wherein one of said outlets is downstream from the other of said outlets; 
 wherein each of said outlet is a circumferential outlet having a plurality of spaced discrete openings for the passage of the fuel and air mixture to said combustion chamber.    
   
   
       18 . The combustor of  claim 15 , wherein the difference in residence time has been determined to attenuate combustor pulsations originating from a burning zone within the combustion chamber.  
   
   
       19 . A combustor, comprising: 
 a combustion chamber;    an annular mixing duct;    a fuel injector disposed in flow communication with said annular mixing duct, said fuel injector delivering a fuel into air flowing within said mixing duct to define a fuel and air mixture; and    at least two branch passages connected with said annular mixing duct, each of said at least two branch passages receiving a portion of the fuel and air mixture and delivering the respective portion of the fuel and air mixture to a distinct location within said combustion chamber separate from the other branch passages, wherein the delivery of the fuel and air mixture through each of said at least two branches is phased to prevent the occurrence of fuel air ratio fluctuations.    
   
   
       20 . The combustor of  claim 19 , wherein each of said at least two branch passages accelerates the flow of the fuel and air mixture therethrough; and 
 which further includes a second mixing duct with a plurality of swirler vanes, wherein said plurality of swirler vanes impart swirl to a fuel and air mixture discharged into a primary combustion zone within the combustion chamber.