Combustion chamber for a gas turbine and burner arrangement

Abstract

A combustion chamber ( 10, 20 ) for a gas turbine ( 1 ) with at least two combustion zones ( 23, 24 ) and at least one burner arrangement ( 11, 28 ) for the combustion of a fuel/air mixture in the combustion zones ( 23, 24 ). The burner arrangement ( 11, 28 ) has at least one premixing passage ( 29 ) that opens into the combustion zones ( 23, 24 ) to provide a fuel/air mixture, and an air supply ( 32 ) and at least one fuel supply ( 33 ) encompassed in the burner arrangement ( 11, 28 ) and open into the premixing passage ( 29 ). The combustion chamber permits a particularly effective damping of combustion chamber pressure fluctuations. To this end, the air supply ( 32 ) is designed in a stepped manner such that the outlet openings ( 34, 34 a, 34 b, 34 c ) of the stepped air supply that open into the premixing passage can be assigned different delay times (τ 1 , τ 2 , τ 3 ), which damps the fluctuations.

1 . A combustion chamber for a gas turbine comprising:
 at least one combustion zone and   at least one burner arrangement configured for combustion of a fuel/air mixture in the combustion zone,   the burner arrangement comprising at least one premixing passage which opens into the combustion zone and which provides a fuel/air mixture, at least one fuel supply which opens into the premixing passage, and   an air supply which is of stepped form such that it comprises a plurality of outlet openings, each outlet opening opens into the premixing passage and is configured to provide air flowing through the premixing passage to the combustion zone with a respective different delay time than air provided by the other outlet openings of the stepped air supply, wherein the delay time is defined as the time required for a fluid element entering the premixing passage to pass to the combustion zone, wherein, for a minimum delay time τ min  and a maximum delay time τ max  of the stepped air supply with regard to a combustion chamber pressure fluctuation having a frequency f, which fluctuation is to be suppressed, the following applies: τ max −τ min >1/f, and the outlet openings of the stepped air supply, which open into the premixing passage are arranged such that the density fluctuations, caused by at least one predominant combustion chamber pressure fluctuation of frequency f′, in the fluid supplied through the outlet openings are superposed on one another in the premixing passage owing to the different delay times assigned to the outlet openings, in such a way that the density fluctuations substantially cancel one another out.   
     
     
         2 . The combustion chamber as claimed in  claim 1 , further comprising, the fuel supply which opens into the premixing passage which is configured to be charged with gaseous fuel also is of stepped form. 
     
     
         3 . The combustion chamber as claimed in  claim 1 , further comprising:
 the at least one combustion zone comprises a first combustion zone followed downstream by a second combustion zone;   the burner arrangement is arranged in the region of a second axial stage of the combustion zone and includes at least one premixing passage that opens into the second combustion zone ( 24 ), and a second burner arrangement in the first combustion zone.   
     
     
         4 . The combustion chamber as claimed in  claim 3 , further comprising:
 the burner arrangement comprises a fuel distributor ring arranged around an outside of a combustion chamber housing around the combustion zone and the burner arrangement comprises multiple premixing passages, each being open at one end thereof into the second combustion zone in the combustion chamber housing and each corresponding to at least one fuel supply that branches off from the fuel distributor ring into the premixing passage, wherein a plurality of the outlet openings of a stepped air supply are distributed along at least one of the premixing passages.   
     
     
         5 . A gas turbine comprising at least one of the combustion chambers, as claimed in  claim 1 . 
     
     
         6 . (canceled) 
     
     
         7 . The combustion chamber as claimed in  claim 1 , further comprising the outlet openings being located distributed along the premixing passage, thereby to cause the minimum and maximum delay times by the location of the openings.