Exhaust nozzle having a compliant shell for a gas turbine engine

An exhaust nozzle for use with a gas turbine engine includes an outer shroud, an inner plug spaced radially apart from the outer shroud, and at least one support vane that is coupled to the outer shroud. The outer shroud and the inner plug cooperate to provide an exhaust nozzle flow path therebetween. The at least one support vane interconnects the outer shroud and the inner plug to support the inner plug in the exhaust nozzle flow path.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to gas turbine engines, and more specifically to variable exhaust nozzles for use with gas turbine engines.

BACKGROUND

Exhaust nozzles may encounter relatively high temperatures due to their proximity to the turbine and the hot products discharged therefrom. Accordingly, supporting various components in the exhaust nozzle while considering these relatively high temperatures remains an area of interest.

SUMMARY

According to one aspect of the present disclosure, a gas turbine engine includes an engine core and an exhaust nozzle. The engine core may include a compressor configured to receive and compress an airflow, a combustor configured to receive a compressed airflow from the compressor and combust the compressed airflow to produce combustion products, and a turbine configured to interact with the combustion products. The exhaust nozzle may be configured to receive the combustion products from the engine core.

In some embodiments, the exhaust nozzle includes an outer shroud arranged circumferentially about an axis to define an outer boundary surface of an exhaust nozzle flow path, an inner plug arranged circumferentially about the axis to define an inner boundary surface of the exhaust nozzle flow path, and a support vane that extends between the outer shroud and the inner plug through the exhaust nozzle flow path. The inner plug may include a plug-support frame coupled to the support vane, an outer plug shell that covers the plug-support frame. The support vane may include a vane-support frame that interconnects the plug-support frame and the outer shroud and an outer vane shell that covers the vane-support frame.

In some embodiments, both the inner plug and the support vane further include a plurality of fastener units that couple the outer plug shell to the plug support frame and couple the outer vane shell to the vane-support frame. The plurality of fastener units may be configured to allow the outer plug shell to thermally expand and contract relative to the plug-support frame and to allow the outer vane shell to thermally expand and contract relative to the vane-support frame.

In some embodiments, each fastener unit included in the plurality of fastener units includes a wear plate fixed to an inner surface of one of the outer plug shell and the outer vane shell, a fastener that extends through the wear plate and one of the outer plug shell and the outer vane shell, and a nut-plate coupled to one of the plug-support frame and the vane-support frame to receive the fastener and couple the outer plug shell to the plug-support frame and to couple the outer vane shell to the vane-support frame.

In some embodiments, the plurality of fastener units includes an anchor fastener unit and an expansion-permissive fastener unit, the nut plate of the anchor fastener unit being formed to include a circular shaped aperture that receives the fastener of the anchor fastener unit to fix the outer vane shell and the outer plug shell in position relative to the anchor fastener unit, the nut plate of the expansion-permissive fastener unit being formed to include a longitudinal slot that receives the fastener of the expansion-permissive fastener unit.

In some embodiments, the fastener of the expansion-permissive fastener unit is configured to translate through the longitudinal slot as the temperature of the exhaust nozzle changes to allow the outer plug shell and the outer vane shell to thermally expand and contract relative to the plug-support frame and to allow the outer vane shell to thermally expand and contract relative to the vane support frame.

In some embodiments, the longitudinal slot in the nut-plate of the expansion-permissive fastener unit is elongated along a first axis that extends through a center of the fastener of the anchor fastener unit.

According to another aspect of the present disclosure, an exhaust nozzle for a gas turbine engine may include an outer shroud, an inner plug, and a support vane. The outer shroud may be arranged circumferentially about an axis to define an outer boundary surface of an exhaust nozzle flow path. The inner plug may be arranged circumferentially about the axis to define an inner boundary surface of the exhaust nozzle flow path. The support vane may extend between the outer shroud and the inner plug through the exhaust nozzle flow path.

In some embodiments, the inner plug includes a plug-support frame coupled to the support vane, an outer plug shell that covers the plug-support frame, and a plurality of fastener units that couple the outer plug shell to the plug support frame and are configured to allow the outer plug shell to thermally expand and contract relative to the plug-support frame.

In some embodiments, each fastener unit includes a wear plate fixed to an inner surface of the outer plug shell, a fastener that extends through the wear plate and the outer plug shell, and a nut-plate coupled to the plug-support frame to receive the fastener and couple the outer plug shell to the plug-support frame.

In some embodiments, the plurality of fastener units includes an anchor fastener unit and a plurality of expansion-permissive fastener units, the anchor fastener unit being configured to fix the outer plug shell relative to the plug-support frame, the plurality of second expansion permissive fasteners being configured to allow thermal growth of the outer plug shell toward and away from the anchor fastener unit.

In some embodiments, each expansion-permissive fastener unit includes a fastener and a nut plate that is formed to include a longitudinal slot and the fastener is configured to translate through the longitudinal slot as the temperature of the exhaust nozzle changes to allow the outer plug shell to thermally expand and contract relative to the plug-support frame.

In some embodiments, the longitudinal slot in the nut-plate of each expansion-permissive fastener unit is elongated along an axis that extends through a center of the anchor fastener unit. In some embodiments, at least two of the axes are non-parallel to one another. In some embodiments, the anchor fastener unit is located at an axially forward end of the inner plug relative to the central axis and the plurality of expansion-permissive fastener units are located axially aft of the anchor fastener unit.

According to another aspect of the present disclosure, an exhaust nozzle for a gas turbine engine may include an outer shroud, an inner plug, and a support vane. The outer shroud may be arranged circumferentially about an axis to define an outer boundary surface of an exhaust nozzle flow path. The inner plug may be arranged circumferentially about the axis to define an inner boundary surface of the exhaust nozzle flow path. The support vane may extend between the outer shroud and the inner plug through the exhaust nozzle flow path.

In some embodiments, the support vane includes a vane-support frame coupled to the inner plug, an outer vane shell that covers the vane-support frame, and a plurality of fastener units that couple the outer vane shell to the vane support frame and are configured to allow the outer vane shell to thermally expand and contract relative to the vane-support frame.

In some embodiments, each fastener unit includes a wear plate fixed to an inner surface of the outer vane shell, a fastener that extends through the wear plate and the outer vane shell, and a nut-plate coupled to the vane-support frame to receive the fastener and couple the outer vane shell to the vane-support frame.

In some embodiments, the plurality of fastener units includes an anchor fastener unit and a plurality of expansion-permissive fastener units, the anchor fastener unit being configured to fix the outer vane shell relative to the vane-support frame, the plurality of second expansion permissive fasteners being configured to allow thermal growth of the outer vane shell toward and away from the anchor fastener unit.

In some embodiments, the plurality of expansion-permissive fastener unit each include a fastener and a nut plate that is formed to include a longitudinal slot and the fastener is configured to translate through the longitudinal slot as the temperature of the exhaust nozzle changes to allow the outer plug shell to thermally expand and contract relative to the plug-support frame.

In some embodiments, the longitudinal slot in the nut-plate of each expansion-permissive fastener unit is elongated along an axis that extends through a center of the anchor fastener unit. In some embodiments, at least two of the axes are non-parallel to one another.

In some embodiments, the outer vane shell includes a first panel and a second panel, both the first panel and the second panel including an anchor fastener unit at a forwardmost and innermost corner of each panel relative to the central axis that fixes the first panel and the second panel relative to the vane-support frame and a plurality of second expansion permissive fasteners that allow the first panel and the second panel to thermally expand and contract toward and away from the anchor fastener unit of the first panel and the second panel.

In some embodiments, the outer vane shell further includes a joint strip between the first panel and the second panel that provides a clearance gap to allow the first panel to thermally expand toward the second panel away from the anchor fastener unit of the first panel.

DETAILED DESCRIPTION OF THE DRAWINGS

An aerospace gas turbine engine10is shown inFIG. 1and includes a fan12, an engine core14, and exhaust nozzle16. The fan12is coupled to the engine core14for rotation by the engine core14about an axis18during use. The engine core14receives and combusts fuel to drive rotation of one or more shafts (not shown). The exhaust nozzle16is located axially aft of the engine core14and is configured to expel exhaust products produced by the engine core14downstream into the atmosphere.

The engine core14includes a compressor section20, a combustor section22, and a turbine section24as shown inFIG. 1. The compressor section20compresses and delivers pressurized air to the combustor section22. The combustor section22mixes fuel with the pressurized air received from the compressor section20and ignites the fuel. The hot, high-pressure products of the combustion reaction in the combustor section22are directed into the turbine section24to cause portions of the turbine section24to rotate about the axis18and drive portions of the compressor section20. The fan12is also coupled to the turbine section24by at least one of the shafts driven in rotation by the engine core14and provides thrust for propelling an air vehicle when rotated by the turbine section24. The exhaust products of the engine core14are directed into the exhaust nozzle16where a flow of the exhaust products are manipulated by the exhaust nozzle16prior to being released into the atmosphere.

The exhaust nozzle16includes an outer shroud26, an inner plug28, and at least one support vane30as shown inFIGS. 1 and 2. The outer shroud26extends circumferentially around the axis18. The inner plug28cooperates with the outer shroud26to form an exhaust nozzle flow path32therebetween. The at least one support vane30interconnects the outer shroud26and the inner plug28to support the inner plug28in the exhaust nozzle flow path32. The exhaust products from the engine core14flow downstream through the exhaust nozzle flow path32from the engine core14to the atmosphere. The support vane30is mounted to a track34in the outer shroud26for movement of the inner plug28forward and aft along the axis18as suggested by the arrows36shown inFIG. 1. The inner plug28and the at least one support vane30may translate axially relative to the outer shroud26to change a flow path area of the exhaust nozzle flow path32to optimize the flow of exhaust products for low noise emissions during take-off or increased engine efficiency at cruise.

The inner plug28includes a plug-support frame38, an outer plug shell40, and a plurality of plug fastener units42that couple the outer plug shell40to the plug-support frame38as shown inFIG. 2. The plug-support frame38is arranged within an internal space44defined by the outer plug shell40. The outer plug shell40covers the plug-support frame38to provide an aerodynamic outer flow path boundary for the inner plug28. The plug-support frame38is coupled to the outer plug shell40to support the outer plug shell40in the exhaust nozzle flow path32. The plug-support frame38is configured to transfer loads acting on the outer plug shell40to the support vane30and into the outer shroud26. The plurality of fastener units42retain the outer plug shell40to the plug-support frame38while allowing the outer plug shell40to expand and contract relative to the plug-support frame38due to exposure to the hot exhaust products from the engine core14. As such, the outer plug shell40is supported by the plug-support frame38but freely floats relative to the plug-support frame38so that adverse stresses are not imparted on the outer plug shell40or the plug-support frame38as a temperature of the exhaust nozzle changes.

The inner plug28is arranged on the axis18and is supported in the exhaust nozzle flow path32by first and second support vanes30,31as shown inFIGS. 1 and 2. The support vanes30,31are identical to one another except that they are swept forward away from the inner plug28in different directions. Only support vane30will be discussed below and the disclosure related to support vane30is hereby incorporated by reference for support vane31.

The support vane30includes a vane-support frame46, an outer vane shell48, and a plurality of vane fastener units50that couple the outer vane shell48to the vane-support frame46. The vane-support frame46is arranged within an internal space51defined by the outer vane shell48. The outer vane shell48covers the vane-support frame46to provide an aerodynamic outer boundary of the support vane30. The plurality of fastener units50retain the outer vane shell48to the vane-support frame46while allowing the outer vane shell48to expand and contract relative to the vane-support frame46due to exposure to the hot exhaust products from the engine core14. As such, the outer vane shell48is supported by the vane-support frame46but freely floats relative to the vane-support frame46so that adverse stresses are not imparted on the outer vane shell48or the vane-support frame46as a temperature of the exhaust nozzle changes.

The plurality of plug fastener units42are substantially similar to the plurality of vane fastener units50. Accordingly, the vane fastener units50are discussed below with reference toFIGS. 3-6and their disclosure is hereby incorporated by reference for plug fastener units42which are discussed with reference toFIGS. 7-10.

The plurality of fastener units50include an anchor fastener unit52, as shown inFIG. 3, and an expansion-permissive fastener unit252, as shown inFIG. 4. The fastener units52,252are substantially similar to one another except that the anchor fastener unit52provides an anchor point for the outer vane shell48while the expansion-permissive fastener unit252allows movement of the outer vane shell48relative to the vane-support frame46due to thermal expansion and contraction.

The anchor fastener unit52includes a first fastener56, a first wear plate58, and a first mount unit60as shown inFIG. 3. The first fastener56is illustratively embodied as a flat head screw, though any suitable fastener may be used. The first fastener56cooperates with the outer vane shell48to provide a smooth outer flow path surface for the vane30when installed. The first wear plate58is fixed to an inner surface of the outer vane shell48by welding, brazing or another suitable joining process. The first wear plate58has a tapered engagement surface62that receives a head of the first fastener56. The first mount unit60is coupled to the underlying vane-support frame46and receives the first fastener56to couple the outer vane shell48to the vane-support frame46.

The anchor fastener unit52anchors the outer vane shell48to the vane-support frame46using first mount unit60such that thermal expansion of the outer vane shell48is away from the anchor fastener unit52. The first mount unit60includes a first retainer64and a first nut-plate66as shown inFIG. 3. The first nut-plate66includes a body68that is formed to include an aperture70and a pair of attachment flanges72,74coupled to opposite sides of the body68. The body68is offset from the attachment flanges72,74to provide a gap76into which the aperture70opens. The first fastener56protrudes through the aperture70along an axis78into the gap76where it is received by the retainer64. The aperture70in the body68is circular and blocks radial movement of the first fastener56and the outer vane shell48away from the axis78. The retainer64blocks axial movement of the first fastener56and the outer vane shell48along the axis78.

The mount unit60may further include a shim80between the nut plate66and the vane support frame46and side walls81,83as shown inFIG. 3. The shim80may be included to accommodate varying spaces between the outer vane shell48and the underlying vane-support frame46. The side walls81,83are coupled to each open-end of the gap76to enclose the retainer64in the gap76. The side walls81,83may be separate components that are joined by welding or brazing or integral components that are bent inwardly from the body68or either of the flanges72,74. The nut plate66is coupled to the vane support frame46(and the shim80, if included) by a plurality of fasteners82that are secured by nuts85. In other embodiments, the nut plate66may be joined to the vane-support frame by another suitable structure or process such as by a clip, rivet, pin, adhesive, welding, brazing, soldering, etc.

The expansion-permissive fastener unit252is similar to the anchor fastener unit52. The expansion-permissive fastener unit252includes a second fastener256, a second wear plate258, and a second mount unit260as shown inFIG. 4. The second fastener256is illustratively embodied as a flat head screw, though any suitable fastener may be used. The second fastener256cooperates with the outer vane shell48to provide a smooth outer flow path surface for the vane30when installed. The second wear plate258is fixed to an inner surface of the outer vane shell48by welding, brazing or another suitable joining process. The second wear plate258has a tapered engagement surface262that receives a head of the second fastener256. The second mount unit260is coupled to the underlying vane-support frame46and receives the second fastener256to couple the outer vane shell48to the vane-support frame46.

The expansion-permissive fastener unit252is configured to allow thermal expansion and contraction of the outer vane shell48toward and away from the anchor point provided by the anchor fastener unit52. The second mount unit260includes a second retainer264, a retainer clip265, and a second nut-plate266as shown inFIG. 4. The second nut-plate266includes a body268that is formed to include an aperture270, and a pair of attachment flanges272,274coupled to opposite sides of the body268. The body268is offset from the attachment flanges272,274to provide a gap276into which the aperture270opens. The second fastener256protrudes through the aperture270along an axis278and into the gap276where it is received by the retainer264. The aperture270in the body268is formed as a longitudinal slot and allows the second fastener256to move or translate through the slot unrestricted as the outer vane shell48expands. The retainer264blocks axial movement of the second fastener256and the outer vane shell48along the axis278. The retainer clip265interconnects the retainer264and the nut plate266to block rotation of the retainer264about the axis278. This prevents unintentional removal of the retainer264from the second fastener256while still allowing the fastener256and the retainer264to move through the aperture270.

The mount unit260may further include a shim280between the nut plate266and the vane support frame46and side walls281,283as shown inFIG. 4. The shim280may be used to accommodate varying spaces between the outer vane shell48and the underlying vane-support frame46. The side walls281,283may be coupled to each open-end of the gap276to enclose the retainer264in the gap276. The side walls281,283may be separate components that are joined by welding or brazing or integral components that are bent inwardly from the body268or either of the flanges272,274. The nut plate266is coupled to the vane support frame46(and the shim280, if used) by a plurality of fasteners282that are be secured by nuts285. In other embodiments, the nut plate266may be joined to the vane-support frame by another suitable structure or process such as by a clip, rivet, adhesive, welding, brazing, soldering, etc.

In the illustrative embodiment, the fastener units50includes more expansion-permissive fastener units252than anchor fastener units52as shown inFIGS. 5 and 6. Each vane30may have only one anchor fastener unit52while the rest of the fastener units50are expansion-permissive fastener units252. The number of anchor fastener units52included may increase depending on the number of shell panels included in outer vane shell48as will be discussed.

Each expansion-permissive fastener unit252is coupled to the vane-support frame46and oriented to allow thermal expansion and contraction of the outer vane shell toward and away from the anchor fastener unit52as shown inFIGS. 5 and 6. The expansion-permissive fastener units252are spread across the vane-support frame46and spaced apart from one another to provide a plurality of connection points that are distributed across the entire area of the outer vane shell48. The expansion-permissive fastener units252are oriented such that the longitudinal slot270in each second nut plate266is elongated along a respective axis that extends through a center of the anchor fastener unit52as shown inFIG. 6. Some axes (i.e. axis84and axis86) may be parallel and/or coaxial to one another while others (i.e. axes88,90,92,94,96) are non-parallel and spaced apart from one another. The vanes30may have a three-dimensional shape that causes some of the axes to be coplanar with the anchor fastener unit52. Accordingly, in some embodiments, the term parallel may include the term coplanar depending on which direction the axes are viewed from.

In the illustrative embodiment, the anchor fastener unit52is located at a forwardmost and innermost corner98of the outer vane shell48relative to the central axis18as shown inFIG. 5. This corner98generally corresponds to an area of the outer vane shell48that is exposed to the hottest temperatures in the illustrative exhaust nozzle16. The expansion-permissive fastener units252are dispersed away from the anchor fastener unit52and oriented so that the outer vane shell expands away from the anchor fastener unit52as described above.

The outer vane shell48may include a plurality of shell panels as shown inFIG. 2and suggested inFIG. 5. The outer vane shell48in the illustrative embodiment, includes a first shell panel100and a second shell panel102. Each shell panel100,102is coupled to the underlying vane-support frame46by a single anchor fastener unit52and a plurality of expansion-permissive fastener units252. The anchor fastener unit52is located at a forwardmost and innermost corner of each respective panel100,102relative to the central axis18.

The vane30may further include one or more expansion joints104between panels100,102and between vane30and outer shroud26as shown inFIG. 2. The expansion joints104provide slight clearance gap radially between the panels100,102and/or between the outer vane shell48and the outer shroud26to allow them to expand thermally outward away from the anchor fastener unit52. The first shell panel100is configured to grow thermally toward the second shell panel102and the second shell panel102is configured to grow thermally toward the outer shroud26in the illustrative embodiment. However, in other embodiments the panels100,102may be configured to grow thermally in other directions such as toward the inner plug28.

The fastener units42of the inner plug28also include at least one anchor fastener unit52and a plurality of expansion-permissive fastener units252to couple the outer plug shell40to the plug-support frame38as shown inFIGS. 7-10. The outer plug shell40is fixed to the plug-support frame38by the anchor fastener unit52and is allowed to grow relative to the plug-support frame38by a plurality of second fasteners252. The anchor fastener unit52is located at an axially forward end of the inner plug28which in the illustrative embodiment is an area of the inner plug28that is exposed to the highest temperatures. The expansion-permissive fastener units252are located aft of the anchor fastener unit52to allow the outer plug shell40to thermally expand in the aft direction away from the anchor fastener unit52. The anchor fastener unit52and the expansion-permissive fastener unit252may be arranged differently in other embodiments to allow thermal growth of the outer plug shell in a different direction or manner.

The anchor fastener unit52and the expansion-permissive fastener units252are coupled to the plug-support frame38by a spacer bracket380as shown inFIGS. 9 and 10. The spacer bracket380provides a similar function to the shims80,280discussed previously and may be replaced with shims80,280in some embodiments. Alternatively, the fastener units52,252may be sized such that the spacer brackets380and/or shims80,280may be omitted in some embodiments.

In some embodiments, the gas turbine engine10may be used on an aircraft that supports supersonic flight. The engine10include an exhaust nozzle16that may have an integral thrust reverser and the ability to vary the nozzle throat area. The exhaust nozzle16(a nozzle that incorporates an aft center body) may provide a broad efficiency peak across operating ranges of the gas turbine engine10. The shaping of the inner and outer flow path lines provides may efficient operation at the cruise point and quiet operation during takeoff.

In some embodiments, the plug is supported by vanes that are attached to the exhaust nozzle case and transfer load to through the case to the nozzle support system. The plug may be supported by 2, 3, 4 or any suitable number of vanes. These configurations may share a common design feature in that the plug is allowed to grow thermally without adversely affecting the operation of the system, while at the same time passing aerodynamic loads to the vanes and to the outer shroud.

These configurations share a common design feature in that the skin (or panels) that form the aerodynamic flow surfaces on the vanes and center body (plug) are allowed to grow thermally without adversely affecting the operation of the system (the aerodynamic flow) (i.e. reducing binding between components by letting the outer skin grow unrestricted).

In some embodiments, the vanes and forward portion of the plug are covered with skin panels that form the aerodynamic flow path around each vane. The skin panels are sized to control thermal growth and prevent buckling. The skin panels are attached to the vane structure with nut plates that have been configured to allow movement between the underlying structure and the panels.

In some embodiments, this concept controls the thermal movement of the skin by anchoring the panels using one fastener and nut plate (seeFIGS. 3 and 9) in a corner and directing the thermal growth of the panels away from this pin using slotted nut plates (seeFIGS. 4 and 10). The nut plates are oriented to allow the skin to grow away from the pin position in a straight line. Provision may be made to control the sliding and wear of the skin and nut plate by selecting the materials and coatings for the nut plate outer cover and the wear disk bonded to the panel and located between the fastener and the nut plate. The load that the fastener applies to panel and fastener may be selected to meet wear goals for the components. Fastener unit spacing is set to control local panel deformation and has been selected to provide minimal impact to the nozzle performance. The internal arrangement of the thermally compliant skin for a three and four vane configuration may have some minor variations, but the concept may remain the same.