Abstract:
Gas turbine engine systems and methods involving enhanced fuel dispersion are provided. In this regard, a representative method for operating a gas turbine engine includes: providing a gas path through the engine; introducing a spray of fuel along the gas path downstream of a turbine of the engine; and impinging the spray of fuel with a relatively higher velocity flow of air such that atomization of the fuel is increased.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0001]    The U.S. Government may have an interest in the subject matter of this disclosure as provided for by the terms of contract number F33657-99-D-2051 awarded by the United States Air Force. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The disclosure generally relates to gas turbine engines. 
         [0004]    2. Description of the Related Art 
         [0005]    Some gas turbine engines incorporate thrust augmentors, which are commonly known as afterburners. Although provided in various configurations, an afterburner generally incorporates a structure for introducing fuel along the gas path of the engine downstream of the turbine section. In some applications, flameholders can be provided for initiating combustion of the additional fuel. 
       SUMMARY 
       [0006]    Gas turbine engine systems and methods involving enhanced fuel dispersion are provided. In this regard, an exemplary embodiment of a gas turbine engine system comprises: a fuel conduit; a nozzle having an outlet, the nozzle being operative to receive a flow of fuel from the fuel conduit and to disperse the fuel from the outlet; and an airflow director positioned, at least partially, about the fuel conduit and being operative to direct a flow of air toward the fuel dispersed from the outlet such that interaction between the flow of air and the fuel dispersed from the outlet further atomizes the fuel. 
         [0007]    An exemplary embodiment of a gas turbine engine comprises: a combustion section; and an exhaust section located downstream from the combustion section, the exhaust section having an exhaust case and an augmentor assembly; the augmentor assembly having a nozzle assembly and an airflow director, the nozzle assembly being operative to receive a flow of fuel and to disperse the fuel, the airflow director being operative to direct a flow of air from the exhaust case toward the fuel dispersed from the nozzle assembly such that interaction between the flow of air and the fuel dispersed from the nozzle assembly further disburses the fuel. 
         [0008]    An exemplary embodiment of a method for operating a gas turbine engine comprises: providing a gas path through the engine; introducing a spray of fuel along the gas path downstream of a turbine of the engine; and impinging the spray of fuel with a relatively higher velocity flow of air such that atomization of the fuel is increased. 
         [0009]    Other systems, methods, features and/or advantages of this disclosure will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be within the scope of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0011]      FIG. 1  is a schematic diagram depicting an exemplary embodiment of a gas turbine engine. 
           [0012]      FIG. 2  is a schematic diagram depicting a portion of the embodiment of  FIG. 1 . 
           [0013]      FIG. 3  is a schematic diagram depicting a portion of the nozzle assembly of the embodiment of  FIGS. 1 and 2  as viewed along section line  3 - 3 . 
           [0014]      FIG. 4  is a schematic diagram depicting a portion of another exemplary embodiment of a nozzle assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Gas turbine engine systems and methods involving enhanced fuel dispersion are provided, several exemplary embodiments of which will be described in detail. In this regard, pressurized airflows are directed to impinge upon sprays of fuel output from augmentor fuel nozzles. In some embodiments, the airflows are directed from pressurized cavities located within vanes that are positioned across gas paths of the engines. Notably, impingement of the airflows on the fuel can enhance dispersion of the fuel, such as by increasing a degree of atomization. 
         [0016]    Reference is now made to the schematic diagram of  FIG. 1 , which depicts an exemplary embodiment of a gas turbine engine. Specifically, engine  100  is a turbofan that incorporates a compressor section  102 , a combustion section  104 , a turbine section  106  and an exhaust section  108 . Although depicted as a turbofan gas turbine engine, it should be understood that the concepts described herein are not limited to use with turbojets as the teachings may be applied to other types of gas turbine engines. 
         [0017]    As shown in the embodiment of  FIG. 1 , exhaust section  108  defines a core gas path  110  directing a core flow of gas (depicted by arrow A), and a bypass gas path  112  directing a bypass flow of gas (depicted by arrow B). Multiple vanes (e.g., vane  114 ) are positioned circumferentially about a longitudinal axis  116  of the engine, with various components of an augmentor assembly  120  being supported by the vanes. By way of example, location  122  of vane  114  (described in greater detail with respect to  FIG. 2 ) mounts a fuel nozzle for providing a spray of fuel for augmentation. Notably, others of the vanes can support corresponding nozzles so that the augmentor assembly comprises an array of nozzles for directing fuel along the gas path  110 . A tailcone  124  also is located in the exhaust section. 
         [0018]    As shown in  FIG. 2 , vane  114  includes an internal cavity  130  through which a fuel nozzle assembly  132  and an igniter  134  extend. The igniter  134  is operative to ignite the fuel dispersed from the fuel nozzle assembly. In some embodiments, a single igniter can be used, whereas additional igniters (each of which is typically associated with a corresponding fuel nozzle assembly) can be used in other embodiments. 
         [0019]    Fuel nozzle assembly  132  incorporates a fuel conduit  136 , a fuel nozzle  138  and a mounting assembly  140 . Fuel conduit  136  delivers a flow of fuel to a fuel nozzle  138 . Fuel nozzle  138  is positioned to direct a spray of fuel (depicted by dashed lines) from an outlet  139  to gas path  110 . Positioning of the fuel nozzle  138  is facilitated by the mounting assembly  140 . 
         [0020]    In the embodiment of  FIG. 2 , mounting assembly  140  includes two mounting components  142 ,  144 , each of which incorporates an aperture. Specifically, component  142  includes aperture  146 , and component  144  includes aperture  148 . In this embodiment, the components are configured as mounting brackets that removably mount the fuel conduit within the cavity. The apertures are sized and shaped to accommodate passage of the fuel conduit. 
         [0021]    Additionally, one or more gaps formed between an exterior of the fuel conduit and the surfaces defining the apertures  146 ,  148  function as an airflow director. Since the cavity  130  is pressurized during operation, the airflow director directs a flow of air (depicted by arrow C) toward the fuel dispersed from the nozzle outlet  139 . Notably, interaction between the flow of air and the fuel dispersed from the outlet further disperses (e.g., atomizes) the fuel. In this embodiment, the flow of air from the airflow director is generally directed radially inwardly toward a centerline of the engine. 
         [0022]    Source pressure for the airflow is higher than that of gas path  110  and, in this embodiment, is provided from bypass flow  112  ( FIG. 1 ). Typical pressure ratios between the airflows of paths  110  and  112  can vary considerably during operation. By way of example, a range of such pressure ratios (pressure of path  112 /pressure of path  110 ) may be between approximately 1.12 to approximately 1.40. 
         [0023]    It should be noted that the flow of air provided by the airflow director exhibits a relatively higher velocity than other air flowing in a vicinity of the spray of fuel. In this regard, the embodiment of  FIG. 2  provides flows of cooling air for cooling tailcone  124 . Specifically, tailcone  124  incorporates cooling holes (e.g., hole  150 ) through which cooling air (depicted by arrow D, for example) flows. The cooling air from tailcone  124  in this embodiment provides a sufficient film of air to cool the tailcone while not being of high enough velocity to divert fuel spray  138  away from igniter  134 . 
         [0024]    Various influences may affect the flow velocity and volume of airflow provided by the airflow director. Notably, some of these influences include the size and shape of the one or more apertures of the mounting assembly. In this regard, reference is made to  FIG. 3 , which depicts a portion of mounting component  144 . 
         [0025]    As shown in  FIG. 3 , aperture  148  of mounting component  144  provides a continuous, annular gap  160  about the exterior of nozzle assembly  132 . However, in this embodiment, a portion  162  of the gap is larger than a portion  164  of the gap, which is located on the opposing side of the fuel conduit. Specifically, portion  162  of the gap is positioned along a portion of the fuel conduit corresponding to a direction (indicated generally by arrow E) at which the fuel is dispersed from the nozzle. Notably, gap  160  is sized to assist in atomizing fuel (e.g., fuel spray  138 ) while preventing the velocity of the air through the gap from being too high, which can cause fuel to be diverted from an associated igniter. 
         [0026]    In order to achieve the desired gap about the nozzle assembly (e.g., about the fuel conduit), various techniques can be used. By way of example, tolerances used to form one or more of the various components can be established to ensure that the desired spacing is achieved. Additionally or alternatively, another component (e.g., a spacer) can be used to position the nozzle assembly with an aperture. 
         [0027]      FIG. 4  is a schematic diagram depicting a portion of another exemplary embodiment of a nozzle assembly. As shown in  FIG. 4 , mounting component  170  includes an aperture  172 , which provides a gap  174  about a portion of the exterior of a fuel conduit  176 . In this embodiment, the gap extends circumferentially about the fuel conduit up to approximately 90 degrees. In other embodiments, such a gap can extend circumferentially about a portion of a nozzle assembly up to approximately 180 degrees, whereas still others may extend up to approximately 45 degrees. 
         [0028]    It should be emphasized that the above-described embodiments are merely possible examples of implementations set forth for a clear understanding of the principles of this disclosure. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the accompanying claims.