Fuel nozzle

Abstract

A fuel nozzle for a combustor of a gas turbine engine includes a body defining an axial direction and a radial direction, an air passageway defined axially in the body, and a fuel passageway defined axially in the body radially outwardly from the air passageway. The fuel passageway has an outer wall including an exit lip at a downstream portion of the outer wall. The exit lip has a surface treatment including a swirl-inducing relief. A gas turbine engine and a method of inducing swirl in at least one of pressurised fuel and air exiting a fuel nozzle of a gas turbine engine are also presented.

1 . A fuel nozzle for a combustor of a gas turbine engine, the fuel nozzle comprising:
 a body defining an axial direction and a radial direction;   an air passageway defined axially in the body;   a fuel passageway defined axially in the body radially outwardly from the air passageway, the fuel passageway having an outer wall including an exit lip at a downstream portion of the outer wall, the exit lip having a surface treatment including a swirl-inducing relief.   
     
     
         2 . The fuel nozzle of  claim 1 , wherein the swirl-inducing relief extends up to a downstream end of the exit lip. 
     
     
         3 . The fuel nozzle of  claim 1 , wherein the swirl-inducing relief includes a plurality of grooves defined in the exit lip. 
     
     
         4 . The fuel nozzle of  claim 3 , wherein the grooves of the plurality of grooves are helicoidal. 
     
     
         5 . The fuel nozzle of  claim 3 , wherein the fuel passageway includes a first axial portion, a second converging portion extending inwardly from a downstream end of the first axial portion, and a third axial portion extending from a downstream end of the second converging portion, the third axial portion including the exit lip,
 the plurality of grooves being defined in the second converging portion and in the third axial portion.   
     
     
         6 . The fuel nozzle of  claim 1 , wherein the swirl-inducing relief includes a plurality of vanes extending radially inwardly from the exit lip. 
     
     
         7 . The fuel nozzle of  claim 6 , wherein the plurality of vanes are disposed in a circumferential array. 
     
     
         8 . The fuel nozzle of  claim 6 , wherein each of the plurality of vanes includes a first portion and a second portion, the first portion has a radial height configured so that the first portion is adapted to affect mainly the pressurised fuel, and the second portion has a radial height configured so that the second portion is adapted to affect mainly the pressurised air. 
     
     
         9 . The fuel nozzle of  claim 8 , wherein only the first portion is streamlined. 
     
     
         10 . The fuel nozzle of  claim 9 , wherein each of the plurality of vanes includes:
 a pin extending radially inwardly from the exit lip, and   an airfoil portion extending downstream from the pin.   
     
     
         11 . The fuel nozzle of  claim 10 , wherein the airfoil portion has a radial height smaller than that of the pin, the airfoil portion is the first portion, and the second portion is a portion of the pin radially inwardly of the airfoil portion. 
     
     
         12 . The fuel nozzle of  claim 1 , wherein the exit lip is axially downstream relative to a downstream end of the air passageway. 
     
     
         13 . A gas turbine engine comprising:
 a combustor; and   a plurality of fuel nozzles disposed inside the combustor, each of the fuel nozzles including:
 a body defining an axial direction and a radial direction; 
 an air passageway defined axially in the body; 
 a fuel passageway defined axially in the body radially outwardly from the air passageway, the fuel passageway having an outer wall including an exit lip at a downstream portion of the outer wall, the exit lip having a surface treatment including a swirl-inducing relief configured to induce swirl to at least one of pressurised air exiting the air passageway and pressurised fuel exiting the fuel passageway. 
   
     
     
         14 . The gas turbine engine of  claim 13 , wherein the swirl-inducing relief extends up to a downstream end of the exit lip. 
     
     
         15 . The gas turbine engine of  claim 13 , wherein the swirl-inducing relief includes a plurality of grooves defined in the exit lip, and the plurality of grooves configured to induce swirl in the pressurised fuel. 
     
     
         16 . The gas turbine engine of  claim 13 , wherein the swirl-inducing relief includes a plurality of vanes extending radially inwardly from the exit lip. 
     
     
         17 . A method of inducing swirl in at least one of pressurised fuel and air exiting a fuel nozzle of a gas turbine engine, the method comprising:
 carrying pressurised air through an air passageway in the fuel nozzle and carrying pressurised fuel through a fuel passageway disposed radially outwardly from the air passageway in the fuel nozzle; and   directing the pressurised fuel and the pressurised air through a swirl-inducing relief formed on an exit lip of the fuel passageway and inducing swirl in at least one of the pressurised air and the pressurised fuel, the exit lip being disposed at a downstream portion of an outer wall of the fuel passageway.   
     
     
         18 . The method of  claim 17 , wherein directing the pressurised fuel and the pressurised air through the swirl-inducing relief comprises directing the pressurised fuel and pressurised air through a plurality of grooves defined in the exit lip and inducing swirl in the pressurised fuel. 
     
     
         19 . The method of  claim 17 , wherein directing the pressurised fuel and the pressurised air through the swirl-inducing relief comprises directing the pressurised fuel and pressurised air through a plurality of vanes extending radially inwardly from the exit lip and inducing swirl in the pressurised air. 
     
     
         20 . The method of  claim 19 , wherein directing the pressurised fuel and the pressurised air through the plurality of vanes comprises directing the pressurised fuel through a streamlined portion of the plurality of vanes and directing the pressurised air through a swirl-inducing portion of the plurality of vanes.