System and method for reducing combustion dynamics in a turbomachine

Abstract

A turbomachine includes a combustion chamber, and at least one pre-mixer mounted to the combustion chamber. The at least one pre-mixer includes a main body having a first end portion that extends to a second end portion. The first end portion is configured to receive an amount of fuel and an amount of air and the second end portion defines an exit plane from which a fuel-air mixture discharges into the combustion chamber. The turbomachine also includes a combustion dynamics reduction system operatively coupled to the at least one pre-mixer. The combustion dynamics reduction system includes at least one of a boundary layer perturbation mechanism and an acoustic wave introduction system which disrupt a flow pattern of the fuel-air mixture within the at least one pre-mixer.

1 . A turbomachine comprising:
 a combustion chamber;   at least one pre-mixer mounted to the combustion chamber, the at least one pre-mixer including a main body including a first end portion that extends to a second end portion, the first end portion being configured to receive an amount of fuel and an amount of air and the second end portion defining an exit plane from which a fuel-air mixture discharges into the combustion chamber; and   a combustion dynamics reduction system operatively coupled to the at least one pre-mixer, the combustion dynamics reduction system including at least one of a boundary layer perturbation mechanism and an acoustic wave introduction system that disrupt a flow pattern of the fuel-air mixture within the at least one pre-mixer.   
     
     
         2 . The turbomachine according to  claim 1 , wherein the combustion dynamics reduction system includes a boundary layer perturbation mechanism, the boundary layer perturbation mechanism including one of an air/inert injection system operatively coupled to the pre-mixer and mechanical member mounted in the at least one pre-mixer. 
     
     
         3 . The turbomachine according to  claim 2 , wherein the boundary layer perturbation mechanism includes an air/inert injection system, the air/inert injection system including an inlet for receiving an amount of air/inert and an outlet for releasing the amount of air/inert. 
     
     
         4 . The turbomachine according to  claim 3 , wherein the outlet is positioned in the pre-mixer. 
     
     
         5 . The turbomachine according to  claim 4 , wherein the outlet is positioned adjacent the exit plane. 
     
     
         6 . The turbomachine according to  claim 2 , wherein the boundary layer perturbation system includes a mechanical member mounted in the pre-mixer. 
     
     
         7 . The turbomachine according to  claim 6 , wherein the mechanical member comprises at least one protrusion mounted in the pre-mixer, the at least one protrusion modifying the flow pattern of the fuel-air mixture. 
     
     
         8 . The turbomachine according to  claim 7 , wherein the at least one protrusion is mounted adjacent the exit plane. 
     
     
         9 . The turbomachine according to  claim 1 , wherein the combustion dynamics reduction system comprises an acoustic wave introduction system, the acoustic wave introduction system including an acoustic driver operatively connected to the at least one pre-mixer. 
     
     
         10 . The turbomachine according to  claim 9 , wherein the combustion dynamics reduction system includes a fluid introduction system, the fluid introduction system being operatively connected to the at least one pre-mixer. 
     
     
         11 . A method of reducing combustion dynamics in a turbomachine comprising:
 directing a fuel-air mixture through a pre-mixer into a combustion chamber, the pre-mixer; and   reducing combustion dynamics by disrupting a flow pattern of the fuel-air mixture within the at least one pre-mixer.   
     
     
         12 . The method of  claim 11 , wherein reducing combustion dynamics comprises perturbing a boundary layer of the fuel-air mixture passing from the pre-mixer. 
     
     
         13 . The method of  claim 12 , wherein perturbing a boundary layer of the fuel-air mixture comprises injecting air into the fuel-air mixture at an exit plane of the pre-mixer. 
     
     
         14 . The method of  claim 12 , wherein perturbing a boundary layer of the fuel-air mixture comprises passing the fuel-air mixture over at least one mechanical member arranged in the pre-mixer. 
     
     
         15 . The method of  claim 14 , wherein passing the fuel-air mixture over at least one mechanical member arranged in the pre-mixer comprises passing the fuel-air mixture over at least one protrusion mounted in the pre-mixer, the at least one protrusion modifying a flow pattern of the fuel-air mixture. 
     
     
         16 . The method of  claim 15 , wherein passing the fuel-air mixture over at least one protrusion comprises passing the fuel-air mixture over the at least one protrusion arranged at an exit plane of the pre-mixer. 
     
     
         17 . The method of  claim 11 , wherein reducing combustion dynamics comprises perturbing a base portion of a flame at an exit plane of the pre-mixer. 
     
     
         18 . The method of  claim 17 , wherein perturbing the base portion of the flame comprises introducing an acoustic wave into the pre-mixer. 
     
     
         19 . The method of  claim 18 , wherein introducing the acoustic wave into the pre-mixer comprises varying a frequency of the acoustic wave. 
     
     
         20 . The method of  claim 18 , further comprising:
 introducing a fluid into the pre-mixing to further perturb the base portion of the flame.