A fuel injector

Abstract

There is described a fuel injector for a gas turbine engine. The fuel injector comprises an air passageway having an inlet region and an outlet region in fluid communication with the inlet region at an air passageway interface, the inlet region being configured to receive a flow of air from a compressor of the gas turbine engine at an air inlet, the outlet region being configured to receive the flow of air from the inlet region via the air passageway interface and discharge the flow of air to a combustor head of the gas turbine engine. The fuel injector also comprises a fuel passageway having a fuel outlet configured to discharge a flow of fuel into the combustor head. A width of the inlet region in a direction perpendicular to a centreline of the air passageway decreases continuously from the air inlet to the air passageway interface.

What is claimed is: 
     
         1 . A fuel injector for a gas turbine engine, the fuel injector comprising:
 an air passageway having an inlet region and an outlet region in fluid communication with the inlet region at an air passageway interface, the inlet region being configured to receive a flow of air from a compressor of the gas turbine engine at an air inlet, the outlet region being configured to receive the flow of air from the inlet region via the air passageway interface and discharge the flow of air to a combustor head of the gas turbine engine; and   a fuel passageway having a fuel outlet configured to discharge a flow of fuel into the combustor head,   wherein a width of the inlet region in a direction perpendicular to a centreline of the air passageway decreases continuously from the air inlet to the air passageway interface along the centreline of the air passageway.   
     
     
         2 . The fuel injector of  claim 1 , wherein the width of the inlet region decreases non-linearly from the air inlet to the air passageway interface. 
     
     
         3 . The fuel injector of  claim 1 , wherein a cross-sectional profile of the inlet region on a plane perpendicular to the centreline of the air passageway is circular, and wherein a diameter of the inlet region decreases continuously from the air inlet to the air passageway interface. 
     
     
         4 . The fuel injector of  claim 3 , wherein a ratio of a difference between the diameter of the inlet region at the air inlet and the diameter of the inlet region at the air passageway interface to the diameter of the inlet region at the air passageway interface is equal to or greater than 0.5. 
     
     
         5 . The fuel injector of  claim 4 , wherein the ratio of the difference between the diameter of the inlet region at the air inlet and the diameter of the inlet region at the air passageway interface to the diameter of the inlet region at the air passageway interface is equal to or greater than 1. 
     
     
         6 . The fuel injector of  claim 1 , wherein the inlet region is in the form of a bellmouth. 
     
     
         7 . The fuel injector of  claim 1 , wherein the cross-sectional area of the inlet region decreases linearly from the air inlet to the air passageway interface. 
     
     
         8 . The fuel injector of  claim 1 , wherein a cross-sectional profile of the inlet region on a plane coplanar with the centreline of the air passageway is parabolic. 
     
     
         9 . The fuel injector of  claim 1 , comprising a swirler disposed within the air passageway, the swirler including a plurality of vanes configured to increase a component of a velocity of air within the air passageway in a circumferential direction of the air passageway. 
     
     
         10 . The fuel injector of  claim 9 , wherein the plurality of vanes are radially disposed around a deflection body, the deflection body being configured to direct air within the air passageway toward the plurality of vanes. 
     
     
         11 . The fuel injector of  claim 1 , comprising:
 a further air passageway disposed around the fuel passageway and having a further inlet region and a further outlet region in fluid communication with the further inlet region at a further air passageway interface, the further inlet region being configured to receive a further flow of air from the compressor of the gas turbine engine at a further air inlet, the further outlet region being configured to receive the further flow of air from the further inlet region via the further air passageway interface and discharge the further flow of air to the combustor head of the gas turbine engine,   wherein a width of the further inlet region in a direction perpendicular to the centreline of the air passageway decreases continuously from the further air inlet to the further air passageway interface along the centreline of the air passageway.   
     
     
         12 . The fuel injector of  claim 11 , wherein the width of the further inlet region decreases non-linearly from the further air inlet to the further air passageway interface. 
     
     
         13 . The fuel injector of  claim 12 , wherein a ratio of a difference between the diameter of the further inlet region at the further air inlet and the diameter of the further inlet region at the further air passageway interface to the diameter of the further inlet region at the further air passageway interface is equal to or greater than 0.5. 
     
     
         14 . The fuel injector of  claim 13 , wherein the ratio of the diameter of the further inlet region at the further air inlet and the diameter of the further inlet region at the further air passageway interface to the diameter of the further inlet region at the further air passageway interface is equal to or greater than 1. 
     
     
         15 . The fuel injector of  claim 11 , wherein the cross-sectional profile of the further inlet region on a plane perpendicular to the centreline of the air passageway is circular, and wherein a diameter of the further inlet region decreases continuously from the further air inlet o the further air passageway interface. 
     
     
         16 . The fuel injector of  claim 11 , comprising a further swirler disposed within the further air passageway, the further swirler including a plurality of further vanes configured to increase a component of a velocity of air within the further air passageway in a circumferential direction of the further air passageway. 
     
     
         17 . The fuel injector of  claim 1 , wherein at least one of the air inlet is defined by an end face of the fuel injector or the further air inlet is defined by an end face of a body defining the further air passageway. 
     
     
         18 . The fuel injector of  claim 1 , wherein at least one of the air passageway is cylindrical at the air passageway interface or the further air passageway is cylindrical at the further air passageway interface. 
     
     
         19 . A combustion apparatus comprising the fuel injector of  claim 1 , and a combustor head configured to:
 receive air from the air outlet;   receive fuel from the fuel outlet; and   facilitate mixing and atomisation of fuel received from the fuel outlet with air received from the air outlet.   
     
     
         20 . A gas turbine engine for an aircraft, the gas turbine engine comprising:
 the fuel injector of  claim 1 .