Patent Abstract:
A gas turbine engine augmentor nozzle has an inlet for connection to an augmentor fuel conduit and an outlet for expelling a spray of fuel. A passageway between the inlet and outlet is at least partially bounded by outlet end surface portions diverging from each other. The nozzle may be used as a replacement for a non-divergent nozzle and may reorient a fuel jet centerline toward radial.

Full Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a continuation of Ser. No. 10/436,630, filed May 13, 2003, now U.S. Pat. No. 6,971,239, and entitled Augmentor Pilot Nozzle, the disclosure of which is incorporated by reference herein as if set forth at length. 

   BACKGROUND OF THE INVENTION 
   This invention relates to turbine engines, and more particularly to turbine engine augmentors. 
   Afterburners or thrust augmentors are known in the industry. A number of configurations exist. In a typical configuration, exhaust gases from the turbine pass over an augmentor centerbody. Additional fuel is introduced proximate the centerbody and is combusted to provide additional thrust. In some configurations, the augmentor centerbody is integrated with the turbine centerbody. In other configurations, the augmentor centerbody is separated from the turbine centerbody with a duct surrounding a space between the two. U.S. Pat. Nos. 5,685,140 and 5,385,015 show exemplary integrated augmentors. 
   The augmentor may feature a number of flameholder elements for initiating combustion of the additional fuel. Piloting devices are used to stabilize the flame on the flameholders which, in turn, distribute the flame across the flow path around the centerbody. 
   SUMMARY OF THE INVENTION 
   Accordingly, one aspect of the invention involves a turbine engine. A centerbody is positioned within a gas flowpath from upstream to downstream and has a downstream tailcone and a pilot proximate an upstream end of the tailcone. A number of vanes are positioned in the flowpath outboard of the centerbody. A number of fuel injectors are at inboard ends of associated spray bars extending through associated vanes. Each injector has an inlet, an outlet, and a passageway between the inlet and the outlet. The passageway has a first portion directing fuel to impact a transversely extending downstream divergent surface portion and be deflected by said surface portion to be discharged from the injector. A number of igniters are positioned within associated ones of the vanes to ignite the fuel discharged from associated ones of the fuel injectors. 
   In various implementations, the passageway may have a second downstream divergent portion facing and spaced apart from the downstream divergent surface portion and at an angle of less than 5° thereto. The pilot may comprise a channel having upstream and downstream rims and a base. Each injector may be oriented so that a centerline of a jet of fuel discharged from such injector is directed toward the base of the channel. The downstream divergent surface portion may be an inboard surface of a transversely-extending slot. The slot may have a pair of lateral surface portions at lateral extremes of the divergent surface portion and diverging at an angle of 55°-95°. 
   Another aspect of the invention involves a turbine engine augmentor nozzle. The nozzle has a proximal inlet for connection to an augmentor fuel conduit. A nozzle has a distal outlet for expelling a spray of fuel. A passageway extends from upstream to downstream between the inlet and outlet, the passageway being bounded by outlet end surface portions including lateral portions diverging downstream. In various implementations, the lateral portions may diverge downstream at an angle of 55°-95°. The lateral portions may diverge downstream at an angle of 60°-80°. 
   Another aspect of the invention involves a gas turbine engine augmentor nozzle wherein a passageway is bounded by outlet end surface portions defining a laterally elongate slot. The surface portions may include lateral surface portions diverging from each other at an angle of 55°-95° and transverse surface portions extending between the lateral surface portions and diverging from each other at angle of 0°-5°. 
   Another aspect of the invention involves a method for remanufacturing a turbine engine augmentor having a vane and a centerbody. A first fuel nozzle is removed and replaced with a second fuel nozzle. The second fuel nozzle is configured to direct a centerline of a fuel jet in a more radial orientation than a jet of the first fuel nozzle and is configured so that the jet of the second fuel nozzle is more diffuse in at least one direction than the jet of the first fuel nozzle. In various implementations, the second fuel nozzle is configured so that its jet is asymmetric whereas the jet of the first fuel nozzle is symmetric around its centerline. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic longitudinal sectional view of an aircraft powerplant. 
       FIG. 2  is a partial semi-schematic longitudinal cutaway view of a first augmentor for use in the powerplant of  FIG. 1   
       FIG. 3  is an upstream end view of a nozzle of the augmentor of  FIG. 2 . 
       FIG. 4  is a longitudinal sectional view of the nozzle of  FIG. 3 , taken along line  4 - 4 . 
       FIG. 5  is an enlarged view of a distal portion of the nozzle of  FIG. 4 . 
       FIG. 6  is a transverse sectional view of the nozzle of  FIG. 5 , taken along line  6 - 6 . 
       FIG. 7  is a side view of the distal portion of the nozzle of  FIG. 5 . 
       FIG. 8  is a forward-looking view of a trailing end of a vane of the augmentor of  FIG. 2 . 
   

   Like reference numbers and designations in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
     FIG. 1  shows a powerplant  20  having a central longitudinal axis  500 . From fore to aft and upstream to downstream in an aftward direction  501 , the powerplant includes a turbine engine  22  having a downstream turbine exhaust case (TEC)  24 . A duct extension  26  extends from the TEC  24  to join with a housing  30  of an augmentor  32 . A thrust vectoring nozzle assembly  34  extends downstream from the housing  30 . The augmentor  32  includes a centerbody  38  centrally mounted within the gas flowpath by means of vanes  40  having trailing edge flameholders  42 . 
   The centerbody  38  is generally symmetric around the axis  500 . The centerbody has a forward tip  50  from which a continuously curving convex forebody or ogive  52  extends rearward until reaching a longitudinal or nearly longitudinal transition region  54  adjacent the flameholders  40 . Aft of the transition region, the centerbody surface defines a pilot channel  56 . A tailcone surface  58  extends aft from the pilot to an aft extremity of the centerbody. 
     FIG. 2  shows further details of an exemplary pilot. The annular pilot channel  56  is formed by a frustoconical surface  60  extending rearward and radially inward from a junction with the transition region  54  of  FIG. 1 . The surface  60  forms the fore (upstream) wall of an annular channel, with the junction forming the fore rim. A longitudinal surface  62  extends aft from a junction with the inboard extremity of the surface  60  and forms a base of the channel. A frustoconical aft wall surface  64  extends rearward and radially outward from a junction with the surface  62  and forms an aft wall of the channel. A longitudinal rim surface  66  extends aft from a junction with the surface  64  that defines a channel aft rim. The surface  66  provides a transition to the tailcone surface  58 . A jet  70  of fuel is delivered to the pilot via nozzle  72  in an appropriate conduit. An exemplary conduit is shown as a spraybar  80  mounted within a vane body  82  ahead of the flameholder  42 . The spraybar  80  has a plurality of lateral nozzles (not shown) delivering jets of fuel from the two sides of the body  82 . The nozzle  72  is positioned at the end of the spraybar. In operation, the pilot channel serves to divert the generally recirculating pilot flow  600  from a principal (main) flow  602 . The jet  70  of fuel is introduced to the pilot flow  600  and combustion is induced by electric spark from an associated igniter  84 . Fuel is also delivered to the principal flow  602  via the spraybar lateral nozzles noted above. The combusted/combusting fuel/air mixture in the flow  600  propagates around the pilot channel  56  stabilize and propagate flame radially outward to the flameholder bodies  82 . Optionally, the centerbody may be provided with several conduits (not shown) for ejecting air jets. There may be a ring of such conduits. The conduits may be supplied from one or more supply conduits (not shown) extending through or along the vanes to the centerbody ahead of the pilot. 
     FIGS. 3-7  show further details of the nozzle  72 . The nozzle extends from a proximal (upstream) end  100  ( FIG. 3 ) to a distal (downstream) end  102  ( FIG. 5 ). The nozzle has an inlet  104  at the upstream end and an outlet  106  ( FIG. 7 ) at the distal end. A passageway  110  extends between the inlet and outlet and has a stepped longitudinal portion extending from the upstream end and including a series of progressively smaller diameter bores  112 ,  114 ,  116  and  118 . The distal (downstream) end of the final/smallest bore  118  merges with a proximal (upstream) end of a slot  120 , the downstream portion of which forms the outlet  106 . The slot  120  has a pair of generally flat transversely-extending distal and proximal walls  122  and  124  joined at their sides by lateral walls  126  and  128  ( FIG. 6 ). The walls  122  and  124  are at an angle θ 1  to each other and the lateral walls  126  and  128  are divergent at an angle θ 2  to each other. In the exemplary embodiment, θ 1  is relatively shallow (e.g., between about 0 and 5°, whereas θ 2  is substantially greater (e.g., between about 55° and 95° (more narrowly 60° and 80° with an exemplary nominal 75°±2°). The slot  120  opens on a circumferential surface  130  of the distal portion of the nozzle having a radius R ( FIG. 6 ). In the exemplary embodiment, the center of curvature of this surface  130  is approximately coincident with the center  132  of the opening of the distal bore  118  to the slot  120 .  FIG. 3  further shows the nozzle as having a fuel pad  140  for lateral injection of fuel. In a basic method of manufacture, the overall shape of the nozzle may be cast and the bores then drilled and the slot machined such as via an end mill. 
   In operation, the downstream-moving fuel exiting the distal bore  118  impacts the surface  122  and fans outward, constrained by the walls  126  and  128 . This deflection creates a relatively flat fan spray. The surface  124  may also help define the fan but is not as important as the surface  122 . When compared with a similar flow jet emitted from a circular outlet having a cylindrical wall upstream thereof, the jet  70  is more spread out, at least in the direction of divergence of the slot. The filming effect of the deflection by the surface  122  contributes to further reduced droplet size. Returning to  FIG. 2 , the jet is shown having a centerline  150  and approximate inboard and outboard extremes  152  and  153 . The centerline  150  is at a projected angle θ 3  relative to the longitudinal aftward direction  602 . The projection is associated with the centerline  150  being oriented slightly skew to the engine axis and having a projected angle θ 4  relative to a radial direction.  FIG. 8  further shows the lateral extremes  154  and  155  of the jet fanning out at an angle θ 5  which may be slightly more than θ 2 . In an exemplary implementation, θ 3  is approximately 40° (more broadly 30°-50°) and θ 4  is 25° (more broadly 20°-30°). Referring to  FIG. 2 , the angle θ 6  between inboard and outboard extremes  152  and  153  will reflect more dispersion relative to its associated surface angle θ 1  than does the angle θ 5  to the relatively larger θ 2 . An exemplary θ 6  is in the vicinity of 20°-40°. 
   Advantageously, the slot configuration is selected in view of the position and orientation of the nozzle and dimensions of the pilot so as to provide reliable augmentor lighting. It is desirable to provide an appropriate mist of fuel within the pilot flow  600 . Reliable ignition of this fuel involves having sufficient quantity and fineness of droplets in proximity to the operative (e.g., inboard) end  160  of the igniter  84 . This operative end protrudes from a longitudinally oriented inboard aft surface  162  of the vane spaced aft of the nozzle outlet and along with the nozzle through one or more apertures (e.g., a common aperture  164 ) in such surface. Flameholder cooling air may also pass radially inward through such aperture(s). The angle θ 4  of  FIG. 8  is selected in view of local tangential velocity components of the air flowing over the vanes so as to inject fuel on either side of the igniter circumferentially. In the exemplary embodiment, the jet centerline  150  is directed toward a midportion of the surface  62  (e.g., in the central 50% thereof). This is in distinction to the prior art circular cylindrical outlets oriented at much shallower angles so as to be directed aft of such a surface. This redirection facilitates greater recirculation of the fuel in the flow  600 . This is facilitated because the more defuse spray places appropriate amounts of fuel in proximity to the igniter operative end  160  with the centerline  150  at an orientation facing farther away from such end. 
   One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, although the illustrated outlet surfaces are shown as straight in section, other configurations such as curved horn-like configurations are possible. In such curved configurations, identified angles could refer to local angles or average angles of portions of the surfaces. Although the illustrated slot is asymmetric about its centerline, symmetric outlets (e.g., outlets producing a conical jet of relatively high included angle (e.g., 80°-120° or, more narrowly, 90°-110°), are also possible to provide alternate divergence. The inventive pilot may be applied in a retrofit or redesign of an otherwise existing engine. In such cases, various properties of the pilot would be influenced by the structure of the existing engine. While illustrated with respect to an exemplary remote augmentor situation, the principles may be applied to non-remote augmentors. Accordingly, other embodiments are within the scope of the following claims.

Technology Classification (CPC): 5