Fuel nozzle

Abstract

A method of delivering fuel from a fuel nozzle of a gas turbine engine includes carrying by a fuel passageway of the fuel nozzle a film of pressurised fuel, the fuel passageway being disposed radially outwardly from an air passageway carrying a flow of pressurised air, and directing the film of pressurised fuel onto an inside surface of an exit lip of an outer wall of the fuel passageway and thinning the film of pressurised fuel as it travels therealong. The exit lip generally increases in diameter as it extends downstream.

1 . A method of delivering fuel from a fuel nozzle of a gas turbine engine, the method comprising:
 carrying by a fuel passageway of the fuel nozzle a film of pressurised fuel, the fuel passageway being disposed radially outwardly from an air passageway carrying a flow of pressurised air; and   directing the film of pressurised fuel onto an inside surface of an exit lip of an outer wall of the fuel passageway and thinning the film of pressurised fuel as it travels therealong, the exit lip generally increasing in diameter as it extends downstream.   
     
     
         2 . The method according to  claim 1 , wherein the exit lip creasing in diameter as it extends downstream includes a flaring portion; and
 directing the film of pressurised fuel onto the inside surface of the exit lip comprises directing the pressurised fuel onto an upstream end of the flaring portion and breaking a first portion of the film of pressurised fuel into a first plurality of droplets; and   directing a remaining of the film of pressurised fuel onto a downstream end of the flaring portion and breaking a second portion of the film of pressurised fuel into a second plurality of droplets.   
     
     
         3 . The method according to  claim 1 , wherein the air passageway carrying the flow of air is a primary air passageway carrying a primary flow of air; and
 the method further comprises carrying a secondary flow of air in a secondary air passageway disposed radially outwardly from the primary fuel passageway.   
     
     
         4 . The method according to  claim 1 , wherein the exit lip includes a plurality of circumferentially arranged tabs extending radially outwardly from the outer wall of the fuel passageway; and
 the method further comprises directing by pressure difference a portion of the secondary flow of air from an outside of the exit lip to an inside of the exit lip via gaps defined between the tabs.   
     
     
         5 . The method according to  claim 4 , further comprising directing the portion of the secondary flow of air in a radial direction through the gaps, the gaps being circumferentially arranged between the tabs. 
     
     
         6 . The method according to  claim 4 , further comprising shearing the film of pressurized fuel using the radial flow of the portion of the secondary airflow. 
     
     
         7 . The method according to  claim 1 , further comprising imparting a twisting component to the film of pressurised fuel, each of the tabs being twisted about a tab length-wise direction. 
     
     
         8 . The method according to  claim 1 , further comprising ejecting the film of pressurised fuel from the flaring portion at an fuel ejection angle that is circumferentially inclined relative to a central axis of the fuel nozzle.