Patent Publication Number: US-9423137-B2

Title: Fuel injector with first and second converging fuel-air passages

Description:
TECHNICAL FIELD 
     The present invention generally relates to devices for delivering fuel, and more particularly, but not exclusively, to fuel injectors for gas turbine engines. 
     BACKGROUND 
     Providing a fuel/air mixture to a combustor of an internal combustion engine remains an area of interest. Some existing systems have various shortcomings relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY 
     One embodiment of the present invention is a unique fuel injector. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for mixing fuel and air. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  depicts one embodiment of a gas turbine engine. 
         FIG. 2  depicts one embodiment of a fuel injector. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     With reference to  FIG. 1 , a gas turbine engine  50  is disclosed that includes a compressor  52 , combustor  54 , and turbine  56 . As air enters the gas turbine engine it is compressed by the compressor  52  and mixed with a fuel delivered by a fuel injector  58 . The fuel injector  58  can be located a variety of places within the gas turbine engine and is not limited to the location depicted in  FIG. 1 . The fuel/air mixture is combusted in the combustor  54  before being delivered to the turbine  56 . As used herein, the term “air” refers to any oxidizer suitable for use with a fuel that is to be combusted in the combustor  54 , whether or not the oxidizer takes the form of atmospheric air. Similarly, the fuel can take a variety of forms suitable for use in gas turbine engines. 
     Though the gas turbine engine  50  is depicted as having a single compressor and single turbine, in other embodiments the gas turbine engine  50  can have any number of compressors and turbines. In addition, the gas turbine engine  50  can have any number of shafts coupling the compressors and turbines to create separate spools. In a few non-limiting examples of embodiments, the gas turbine engine  50  can take the form of a turboshaft, turboprop, or turbofan engine. In addition, the gas turbine engine  50  can be an adaptive or variable cycle engine. The gas turbine engine  50  can also be an axial flow engine, centrifugal flow engine, or a hybrid of each. In short, the gas turbine engine  50  and/or its individual components can take on a variety of forms and be used in a variety of applications. 
     In some applications the gas turbine engine  50  can be used as a powerplant for an aircraft. As used herein, the term “aircraft” includes, but is not limited to, helicopters, airplanes, unmanned space vehicles, fixed wing vehicles, variable wing vehicles, rotary wing vehicles, unmanned combat aerial vehicles, tailless aircraft, hover crafts, and other airborne and/or extraterrestrial (spacecraft) vehicles. Further, the present inventions are contemplated for utilization in other applications that may not be coupled with an aircraft such as, for example, industrial applications, power generation, pumping sets, naval propulsion, weapon systems, security systems, perimeter defense/security systems, and the like known to one of ordinary skill in the art. 
     Turning now to  FIG. 2 , a view of one embodiment of the fuel injector  58  is shown. The fuel injector  58  is used to atomize liquid fuel and mix the fuel with an air stream before being combusted in the combustor  54 . In one form the fuel injector  58  can be used to provide fuel to a lean burning combustor  54  of the gas turbine engine  50 . Generally speaking, the rate of vaporization of a liquid fuel can be enhanced by increasing the total surface area of the liquid fuel in relation to the mass of fuel. For example, by forming the liquid fuel into droplets or forms other than a bulk liquid the rate of vaporization can be increased. Such increase in the surface area relative to its mass can be made possible by atomizing the fuel using a variety of approaches. The plain jet airblast atomizer and fuel filming are two such approaches, but by no means the only approaches. The fuel injector  58  of the present application uses both plain jet airblast and fuel filming in some embodiments as will be described further below, but the injector  58  is not limited to these particular approaches. 
     In the illustrated form the fuel injector  58  includes passageways  60 ,  62 , and  64  which are used to convey air to be mixed with fuel and eventually combusted. The passageways  60 ,  62 , and  64  are annular passageways arranged about a reference line  65  of the injector. Though only three passageways  60 ,  62 , and  64  are shown in the illustrated embodiment, other embodiments can include additional passageways. The passageways  60 ,  62 , and  64  are arranged to admit air at an upstream side and discharge the air at a downstream side and in general can have a variety of shapes and orientations in any given embodiment. In the illustrated form the passageways each include a portion that directs air from a radially outer location and toward the reference line  65 . The passageways  60 ,  62 , and  64  can have a variety of lengths and are offset from each other, as shown for example in the illustrated embodiment. In addition, the passageways  60 ,  62 , and  64  can have a variety of cross sectional areas, including a variety of areas that are different across the passageways. In some forms the passageways  60 ,  62 , and  64  can have a cross sectional area that decreases along its length which can be used to accelerate the flow therein. The inlets and outlets of the passageways  60 ,  62 , and  64  can be located at a variety of axial locations. As can be seen in the illustrated embodiment, the inlets and outlets are axially offset from one another. In some forms, however, two or more of the inlets and/or outlets can have the same axial location. 
     In the illustrated embodiment the airflow passing through the passageways  60 ,  62 , and  64  is influenced by action of swirlers  66 ,  68 , and  70 , respectively. The swirlers  66 ,  68 , and  70  are used to impart a rotational component to the airflow in the passageways  60 ,  62 , and  64 . Any of the swirlers  66 ,  68 , and  70 , or portions thereof, can be disposed within the passageways  60 ,  62 , and  64 . In addition, the swirlers  66 ,  68 , and  70  can be external to the passageways  60 ,  62 , and  64  and structured to deliver air to the passageways. Many different types of swirlers can be used such as, but not limited to, vane type swirlers and swirlers formed of a plurality of discrete air passages arranged at an angle relative to the direction of incoming airflow. The swirlers can be arranged circumferentially around the injector  58 . In some forms of the injector  58  one or more of the swirlers  66 ,  68 , and  70  can be different from the others. 
     In one embodiment the fuel injector  58  includes an outer fuel conduit  72  and an inner fuel conduit  74 . The outer fuel conduit  72  is arranged to deliver fuel to the passageway  62  through an outer aperture  76 . The outer aperture  76  can be located downstream of the swirler  68  as shown in the illustrated embodiment, but in other forms the outer aperture  76  can be located to deliver fuel at the location of the swirler  68 . The fuel in the outer fuel conduit  72  can be pressurized to a variety of pressures by a fuel pump (not shown) or other suitable device and can be delivered through the outer aperture  76  at a variety of flow rates and temperatures. The outer aperture  76  can take a variety of forms including, but not limited to, a hole or a slot. In addition, multiple outer apertures  76  can be used to deliver fuel to the passageway  62 . In some non-limiting embodiments the outer fuel conduit  72  and outer aperture  76  can be operated to provide a plain jet injector to the passageway  62 . 
     The outer fuel conduit  72  and/or outer aperture  76  can be used to provide a fuel jet at a variety of angles relative to the surface of the passageway  62  in which fuel is injected. During operation, air is used to strip fuel from the fuel jet to create ligaments or droplets of fuel of varying sizes and shapes. Such action serves to spread fuel radially, circumferentially, or a combination of the two in the passageway  62 . In some instances the fuel jet can be entirely atomized before reaching an opposite surface of the passageway  62 . In other instances, however, the jet can reach across the passageway  62  and contact the opposite surface in which instance a film of fuel can be formed when the fuel adheres to the opposite surface. Such a film can be encouraged to flow downstream by an air passing through the passageway  62  where some of the fuel can be atomized. The fuel reaching the end of the passageway can be further atomized when it is sheared between the air converging from passageway  62  and passageway  60 . 
     The embodiment depicted in  FIG. 2  shows the plain jet exiting the outer aperture  76  on a radially inner surface of the passageway  62 . Some forms of the fuel injector  58 , however, can arrange for fuel to enter the passageway  62  at other locations, such as, but not limited to, through an exit aperture formed on the radially outer wall of the passageway  60 . The description herein regarding the injection of fuel into the passageway  60  is therefore not limited to fuel exiting on a radially inner surface of the passageway  60 . 
     The inner fuel conduit  74  is arranged to deliver fuel to the passageway  64  through an inner aperture  78 . The fuel in the inner fuel conduit  74  can be pressurized to a variety of pressures by a fuel pump (not shown) or other suitable device and can be delivered through the inner aperture  78  at a variety of flow rates and temperatures. The inner aperture  78  can take a variety of forms including, but not limited to, a hole or a slot. In addition, multiple inner apertures  78  can be used to deliver fuel to the passageway  64 . In some forms the inner fuel conduit  74  and inner aperture  78  can be operated to provide a film of fuel to the passageway  62 . 
     When operated as a fuel filmer, the inner fuel conduit  74  can provide fuel to a fuel filming surface  80  downstream of the inner aperture  78 . The fuel film can then be conveyed downstream, and some fuel can be atomized in the process, by an air passing from the passageway  64 . The fuel reaching the end of the fuel filming surface  80  can then be atomized, either additionally or alternatively to any atomization that has already occurred, when the fuel film is sheared between the air converging from passageway  62  and air from passageway  60  that has traversed along the fuel filming surface. 
     In one embodiment the fuel injector  58  can include a fuel swirler  82  to impart a rotational component to a fuel flowing through the inner fuel conduit  74 . The fuel swirler  82  can be positioned at a variety of locations within the inner fuel conduit  74  and can take on a variety of forms. In one non-limiting example the fuel swirler can include a plurality of angled slots of any of various number, dimensions, and angles. 
     The fuel injector includes a throat which in the illustrative embodiment is depicted as reference numeral  84 . It will be understood that the throat  84  in  FIG. 2  merely depicts the upper half of a throat of a fuel injector  58  that is symmetric about the reference line  65 . Not all forms of the fuel injector  58 , however, need be symmetric about the reference line  65 . Each of the passageways  60 ,  62 , and  64  are arranged to be merged upstream of the throat  84 , but in some embodiments one or more of the passageways  60 ,  62 , and  64  can be arranged to terminate at the throat  84 . 
     In one form of operation the outer fuel conduit  72  is used as part of a main fuel injector circuit and the inner fuel conduit  74  is used as part of a pilot fuel injector circuit. However, not all embodiments of the fuel injector  58  are so limited. In particular, though the terms main fuel injector circuit and pilot fuel injector circuit can be used to describe either of the fuel conduits, no limitation is hereby intended as to whether the particular fuel circuit is to function only as a pilot or as a main in every embodiment of the fuel injector  58 . 
     Furthermore, the gas turbine engine  50  can include other injectors  58 , or the injector  58  can have other variations not explicitly disclosed herein. For example, in one non-limiting form the injector  58  can include additional openings for the delivery of fuel and/or the introduction of air. 
     One aspect of the present application provides an apparatus comprising a gas turbine engine having a fuel injector including a first fuel circuit for delivering fuel to a first air passage and a second fuel circuit for delivering fuel to a second air passage, the first fuel circuit structured to deliver fuel transverse to an airflow passing through the first air passage and the second fuel circuit including a fuel filmer structured to deliver fuel to a shear region of the fuel injector defined by the airflow from the first air passage and an airflow from the second air passage. 
     One feature of the present application provides wherein the first fuel circuit includes a plain jet injector, and wherein a side of the first air passage that includes a discharge opening of the plain jet injector extends to the shear region of the fuel injector, the shear region defined by a convergence of the first air passage and the second air passage. 
     Another feature of the present application provides wherein the first air passage includes a first air swirler and a second air passage includes a second air swirler. 
     Still another feature of the present application includes a third air passage having a third air swirler located radially outward of the second air swirler, the third air passage merging with the second air passage downstream of the plain jet injector. 
     Still yet another feature of the present application provides wherein the first fuel circuit is a main fuel circuit and the second fuel circuit is a pilot circuit. 
     A still further feature of the present application provides wherein the fuel injector of the gas turbine engine is operable to produce a film of fuel on a surface of the first air passage opposite the plain jet injector, the surface of the first air passage terminating at a convergence of the first air passage and a third air passage having a third air swirler. 
     Still yet a further feature of the present application provides wherein the second fuel circuit includes an opening structured to deliver fuel to a filming surface of the second air passage, the second fuel circuit including a fuel swirler upstream of the opening. 
     Yet still a further feature of the present application provides wherein the first fuel circuit includes a plain jet injector structured to deliver fuel in a direction away from the second fuel circuit and toward an air passage that includes a third air swirler. 
     Another aspect of the present application provides an apparatus comprising a gas turbine engine fuel injector including a plain jet injector structured to deliver fuel transverse to a first air passage and a fuel filmer disposed in a second air passage, the first air passage adjacent the second air passage wherein the fuel filmer is structured to deliver fuel to a confluence of the first air passage and the second air passage. 
     A feature of the present application provides the first air passage located radially outward of the second air passage. 
     Another feature of the present application includes a first swirler structured to impart a swirl to an airstream traversing the first air passage, and a second swirler structured to impart a swirl to an airstream traversing the second air passage. 
     Yet another feature of the present application provides wherein the plain jet injector is positioned downstream of the first swirler. 
     Yet still another feature of the present application provides wherein the plain jet injector is operable to deliver a liquid fuel to a surface of the first air passage opposite the plain jet injector, the liquid fuel delivered to the surface forming a film of fuel. 
     Still yet another feature of the present application includes a third air passage having a third air swirler, the liquid fuel conveyed to a convergence of the first air passage and the third air passage. 
     A further feature of the present application provides wherein the gas turbine engine fuel injector is coupled with a gas turbine engine and is structured to deliver fuel to a combustor of the gas turbine engine. 
     A still further feature of the present application includes a main fuel circuit having the plain jet injector and a pilot fuel circuit having the fuel filmer. 
     A further aspect of the present application provides an apparatus comprising a gas turbine engine having a combustor and a fuel injector structured to deliver fuel to the combustor, the fuel injector having a first fuel opening operable to deliver fuel to a first air passage and a second fuel opening operable to deliver fuel to a second air passage, and means for mixing fuel delivered through the first fuel opening with fuel delivered through the second fuel opening. 
     A feature of the present application includes means for intermixing a fuel film in the first air passage with an air traversing a third air passage. 
     Yet still a further aspect of the present application provides a method comprising providing a first fuel to a first air passage through a first aperture, atomizing the first fuel in the first air passage, delivering a second fuel to a second air passage, filming the second fuel along a film surface in the second air passage to create a fuel film, and shearing the fuel film between an air traversing the first air passage and an air traversing the second air passage. 
     A feature of the present application includes swirling the air traversing the first air passage upstream of the atomizing. 
     Another feature of the present application includes imparting a rotational flow component to the second fuel. 
     Yet another feature of the present application provides wherein the imparting occurs upstream of the second air passage. 
     Yet still another feature of the present application includes combusting the first fuel and the second fuel in a combustor of a gas turbine engine. 
     Still yet another feature of the present application includes wetting a surface of the first air passage as a result of the providing a first fuel to a first air passage, the wetting including forming a film of fuel on the surface. 
     Another feature of the present application includes swirling air through a third air passage, and conveying the film of fuel to a convergence of the air traversing the first air passage the air traversing the third air passage. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.