Axial stage injection dual frequency resonator for a combustor of a gas turbine engine

Abstract

A gas turbine engine ( 202 ) including a secondary fuel stage ( 218 ) which also functions as a dual frequency resonator. The engine includes a combustor ( 210 ) and a casing ( 205 ) enclosing the combustor to define a volume ( 214 ). The secondary fuel stage includes a nozzle ( 217 ) sized to be effective as a transverse resonator at a high frequency. The nozzle and the volume ( 214 ) of the casing are sized to be effective as a longitudinal resonator at an intermediate frequency.

The invention claimed is: 
     
         1 . A gas turbine engine comprising:
 a combustor;   a casing enclosing the combustor and defining a volume; and   a secondary fuel stage for delivering fuel to the combustor;   wherein the secondary fuel stage comprises a nozzle sized to be effective as a transverse resonator;   and wherein the nozzle and the volume of the casing are configured to be effective as a longitudinal resonator.   
     
     
         2 . The gas turbine engine of  claim 1 , wherein a length of the nozzle is selected to damp vibrations of a selected frequency. 
     
     
         3 . The gas turbine engine of  claim 1 , wherein the nozzle defines an opening, and wherein a cross-sectional width of the opening of the nozzle is selected to damp vibrations of a selected frequency. 
     
     
         4 . The gas turbine engine of  claim 3 , wherein the nozzle is conical with a reduced cross-sectional width toward an outlet of the nozzle. 
     
     
         5 . The gas turbine engine of  claim 1 , wherein a plurality of nozzles are arranged at the secondary fuel stage and wherein an angle between adjacent nozzles in a plane transverse to a longitudinal axis of the combustor is selected so that the secondary fuel stage is effective to damp a selected transverse vibration mode. 
     
     
         6 . The gas turbine engine of  claim 1 , wherein the secondary fuel stage comprises a first nozzle sized to be effective as a transverse resonator at a first frequency and a second nozzle sized to be effective as a transverse resonator at a second frequency different than the first frequency. 
     
     
         7 . The gas turbine engine of  claim 1 , wherein the secondary fuel stage comprises a first nozzle sized to be effective as a transverse resonator at a first frequency and wherein a third fuel stage downstream of the secondary fuel stage comprises a second nozzle sized to be effective as a transverse resonator at a second frequency different than the first frequency. 
     
     
         8 . The gas turbine engine of  claim 1 , wherein the nozzle extends beyond an inner diameter of a combustion liner wall of the combustor. 
     
     
         9 . The gas turbine engine of  claim 1 , wherein the nozzle does not extend beyond an inner diameter of a combustion liner wall of the combustor. 
     
     
         10 . The gas turbine engine of  claim 1 , wherein a ratio of a length to a diameter of the nozzle is in a range of 0.5-5.0. 
     
     
         11 . The gas turbine engine of  claim 1 , wherein a ratio of a diameter of the nozzle to a diameter of the combustor is in a range of 0.01-0.1. 
     
     
         12 . In a gas turbine engine comprising a casing defining a volume enclosing a combustor, a resonator located at a downstream secondary fuel injection location of the combustor, said resonator comprising:
 a fuel line outlet positioned to inject fuel into an inlet of a nozzle effective to deliver fuel to the combustor through the nozzle;   wherein the nozzle is configured to be effective as a transverse resonator for transverse vibrations in a range of 1200-4500 Hz;   and wherein the nozzle and the volume of the casing enclosing the combustor are configured to be effective as a longitudinal resonator for longitudinal vibrations in a range of 50-150 Hz.   
     
     
         13 . The resonator of  claim 12 , wherein a ratio of a length to a diameter of the nozzle is in a range of 0.5-5.0. 
     
     
         14 . The resonator of  claim 12 , wherein a ratio of a diameter of the nozzle to a diameter of the combustor is in a range of 0.01-0.1. 
     
     
         15 . The resonator of  claim 12 , wherein a plurality of nozzles are arranged at the downstream secondary fuel injection location and wherein an angle between adjacent nozzles in a plane transverse to a longitudinal axis of the combustor is selected so to damp a selected transverse vibration mode. 
     
     
         16 . The resonator of  claim 12 , wherein the nozzle extends beyond an inner diameter of a combustion liner wall of the combustor. 
     
     
         17 . The resonator of  claim 12 , wherein the nozzle does not extend beyond an inner diameter of a combustion liner wall of the combustor. 
     
     
         18 . In a gas turbine engine comprising a casing defining a volume and a can-annular combustor disposed within the casing volume, the improvement comprising:
 a plurality of nozzles formed in a wall of the combustor to define a secondary fuel injection location;   a fuel outlet disposed proximate an inlet of each nozzle for delivering a secondary fuel into the combustor through the nozzles;   wherein the nozzles are configured to be effective as a resonator to dampen a transverse frequency mode of pressure oscillations developed within the combustor during operation of the engine; and   wherein the nozzle and the casing volume are jointly configured to be effective as a resonator to dampen a longitudinal frequency mode of the pressure oscillations.   
     
     
         19 . The gas turbine engine of  claim 18 , further comprising a first of the nozzles configured differently than a second of the nozzles to be effective at different respective frequencies. 
     
     
         20 . The gas turbine engine of  claim 18 , further comprising:
 wherein the nozzles are configured to be effective to damp transverse vibrations in a range of 1200-4500 Hz;   and the nozzles and the casing volume are configured to be effective to damp longitudinal vibrations in a range of 50-150 Hz.