Swirler, burner and combustor for a gas turbine engine

Abstract

A swirler for use in a combustor of a gas turbine engine, having a plurality of generally radially inwardly extending passages arranged circumferentially staggered in a circle, each passage having a radially outer inlet end, a radially inner outlet end, first and second generally radially inwardly extending lateral surfaces, and a base surface and top surface, in use of the swirler fuel and air travelling along the passages from their inlet ends to their outlet ends so as to create adjacent to the outlet ends a swirling fuel/air mixture. At least one surface of at least one passage has at least one gas fuel injection hole, wherein the surface, having the gas fuel injection hole, has at least one counterbore radially surrounding the gas fuel injection hole, wherein the gas fuel injection hole is arranged at a base of the counterbore.

1 . A swirler for use in a combustor of a gas turbine engine, the swirler comprising:
 an axis and an annular array of swirler vanes arranged about the axis and at least partly defining a plurality of generally radially inwardly extending passages arranged to create a vortex of fuel and air about the axis,   wherein each passage has a radially outer inlet end, a radially inner outlet end, first and second generally radially inwardly extending lateral surfaces, so that in use of the swirler, fuel and air travelling along the passages from their inlet ends to their outlet ends create adjacent to the outlet ends a swirling fuel/air mixture,   wherein at least one lateral surface comprises at least one gas fuel injection hole,   wherein the surface, having the gas fuel injection hole, comprises at least one counterbore radially surrounding the gas fuel injection hole.   
     
     
         2 . The swirler according to  claim 1 ,
 wherein the counterbore is rectangular-shaped, oval-shaped, elliptical-shaped or circular-shaped.   
     
     
         3 . The swirler according to  claim 1 ,
 wherein at least one surface comprises at least two gas fuel injection holes and at least one counterbore, the counterbore radially surrounding both gas fuel injection holes, wherein the gas fuel injection holes are arranged at a base of the counterbore.   
     
     
         4 . The swirler according to  claim 3 ,
 wherein two counterbores are spaced apart a distance X and the distance X is at least 2d, where d is the diameter of gas fuel injection holes.   
     
     
         5 . The swirler according to  claim 4 ,
 wherein the counterbores have a dimension L and L is at least 2d and a depth D of the counterbore is at least 2d.   
     
     
         6 . The swirler according to  claim 1 ,
 wherein at least one surface comprises at least two gas fuel injection holes and at least two counterbores, wherein each gas fuel injection hole is radially surrounded by its own counterbore and is arranged at a base of this counterbore.   
     
     
         7 . The swirler according to  claim 1 ,
 wherein the surface, having the at least one gas fuel injection hole and the at least one counterbore is a lateral surface.   
     
     
         8 . The swirler according to  claim 1 ,
 wherein the surface, having the at least one gas fuel injection hole and the at least one counterbore is the base surface.   
     
     
         9 . The swirler according to  claim 1 ,
 wherein the counterbore has a depth D below the surface, a width W normal to the direction of an air flow across the surface and a length L generally in line with the direction of the air flow, the gas fuel injection hole has a diameter d;   wherein the length L is at least 4d and/or the width W is at least 3d and/or the depth D is at least 2d.   
     
     
         10 . A burner for a gas turbine engine, comprising:
 at least one swirler according to  claim 1 .   
     
     
         11 . A combustor for a gas turbine engine, comprising:
 at least one burner according to  claim 10 .