Abstract:
An example turbomachine exhaust flow diverting assembly includes an upstream flow diverter disposed about a rotational axis of a turbomachine, and a downstream flow diverter disposed about the rotational axis and axially misaligned with the upstream flow diverter, the upstream flow diverter and the downstream flow diverter both independently moveable between a first position and a second position, the first position permitting more bypass flow from a bypass flow passage to a core flow passage than the second position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 62/086396 filed Dec. 2, 2014. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates generally to diverting flow at or near an exhaust of a turbomachine. 
         [0003]    Gas turbine engines are known and, typically, include a fan delivering air into a bypass duct as propulsion air and to be utilized to cool components. The fan also delivers air into a core engine where it is compressed in a compressor. The compressed air is then delivered into a combustion section where it is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors, driving them to rotate. 
         [0004]    One type of gas turbine engine has multiple bypass streams. In such engine, there is a radially outer bypass flow and a radially inner main bypass flow. Other types of gas turbine engines have other bypass flow arrangements. 
       SUMMARY 
       [0005]    A turbomachine exhaust flow diverting assembly according to an exemplary aspect of the present disclosure includes, among other things, an upstream flow diverter disposed about a rotational axis of a turbomachine, and a downstream flow diverter disposed about the rotational axis and axially misaligned with the upstream flow diverter. The upstream flow diverter and the downstream flow diverter are both independently moveable between a first position and a second position. The first position permits more bypass flow from a main bypass flow passage to a core flow passage than the second position. 
         [0006]    In a further non-limiting embodiment of the foregoing assembly, the upstream flow diverter and the downstream flow diverter move axially between the first position and the second position. 
         [0007]    In a further non-limiting embodiment of any of the foregoing assemblies, the upstream flow diverter is upstream from the downstream flow diverter relative to a direction of flow through the turbomachine. 
         [0008]    In a further non-limiting embodiment of any of the foregoing assemblies, the upstream flow diverter and the downstream flow diverter are disposed along a radially outer boundary of the core flow passage. 
         [0009]    In a further non-limiting embodiment of any of the foregoing assemblies, the assembly includes a radially outer bypass flow passage that is radially outside the core flow passage and the main bypass flow passage. 
         [0010]    In a further non-limiting embodiment of any of the foregoing assemblies, the first position permits more flow from the radially outer bypass flow passage to a core flow passage than the second position. 
         [0011]    In a further non-limiting embodiment of any of the foregoing assemblies, the upstream flow diverter is axially aligned with at least a portion of a turbine engine case of the turbomachine. 
         [0012]    In a further non-limiting embodiment of any of the foregoing assemblies, the downstream flow diverter is downstream from the turbine engine case. 
         [0013]    In a further non-limiting embodiment of any of the foregoing assemblies, the downstream flow diverter in the first position permits more flow to a variable area mixing plane of the turbomachine than the downstream flow diverter in the second position. 
         [0014]    In a further non-limiting embodiment of any of the foregoing assemblies, the downstream flow diverter in the second position permits more flow to a nozzle of the turbomachine than the downstream flow diverter in the first position. 
         [0015]    In a further non-limiting embodiment of any of the foregoing assemblies, the upstream flow diverter comprises a plurality of individual doors distributed annularly about the rotational axis. The upstream flow diverter could instead be a full annular ring extending circumferentially continuously about the axis. 
         [0016]    A turbomachine assembly according to another exemplary aspect of the present disclosure includes, among other things, a core flow passage extending axially from a fan section to an exhaust, a radially inner bypass flow passage that is radially outside the core flow passage, and a radially outer bypass flow passage that is radially outside the radially inner bypass flow passage. An upstream flow diverter is disposed about a rotational axis of a turbomachine. A downstream flow diverter is disposed about the rotational axis and axially misaligned with the upstream flow diverter. The upstream flow diverter and the downstream flow diverter are both independently moveable between a first position and a second position. The first position permits more bypass flow to a core flow passage than the second position. 
         [0017]    In a further non-limiting embodiment of the foregoing assembly, the upstream flow diverter and the downstream flow diverter move axially between the first position and the second position. 
         [0018]    In a further non-limiting embodiment of any of the foregoing assemblies, the upstream flow diverter and the downstream flow diverter are annular. 
         [0019]    In a further non-limiting embodiment of any of the foregoing assemblies, at least a portion of the upstream flow diverter is axially aligned with a turbine exhaust case, and the downstream flow diverter is downstream from the turbine exhaust case relative to a general direction of flow through the turbomachine. 
         [0020]    In a further non-limiting embodiment of any of the foregoing assemblies, the assembly includes a radially outer bypass flow passage that is radially outside the core flow passage and the radially inner bypass flow passage. 
         [0021]    In a further non-limiting embodiment of any of the foregoing assemblies, the first position permits more flow from the radially outer bypass flow passage to a core flow passage than the second position. 
         [0022]    A method of controlling flow through an exhaust of a turbomachine includes, among other things, at a first position, selectively permitting bypass flow to move to a core flow passage, and, at a second position, selectively permitting bypass flow to move to a core flow passage. The first position is axially spaced from the second position. 
         [0023]    In a further non-limiting embodiment of the foregoing method, the first position is at least partially axially aligned with a turbine exhaust case. 
         [0024]    In a further non-limiting embodiment of any of the foregoing methods, the second position is at least partially axially aligned with a variable area mixing plane that is downstream from the turbine exhaust case relative to a general direction of flow through the turbomachine. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0025]    The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: 
           [0026]      FIG. 1  is a cross-sectional view of a multiple bypass stream gas turbine engine having an upstream flow diverter and a downstream flow diverter. 
           [0027]      FIG. 2  is a close-up view of a portion of an exhaust of the engine of  FIG. 1  and showing the upstream flow diverter and the downstream flow diverter. 
           [0028]      FIG. 3  is a close-up view of a portion of an exhaust of the engine of  FIG. 1  showing the upstream flow diverter and the downstream flow diverter moved from the positions of  FIG. 2 . 
           [0029]      FIG. 4  is a close-up view of a portion of an exhaust of the engine of  FIG. 1  showing the upstream flow diverter and the downstream flow diverter moved from the positions of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows an exemplary engine  10  in a schematic manner. A fan section  12  delivers air into a core engine  16 , a radially inner bypass passage  20 , and a radially outer bypass passage  24 . 
         [0031]    A core engine flow C of air is delivered to the core engine  16  from the fan section  12  and moves along a core flow passage  26  of the core engine  16  extending through a compressor section  28 , a combustor section  32 , a turbine section  36 , and then an exhaust section  40 . Compressed air from the compressor section  28  is mixed with fuel and ignited in the combustor section  32 . The products of combustion drive turbine rotors in the turbine section  36  to rotatably drive compressor rotors in the compressor section  28 , and fan rotors  44  and  48  about an axis A. 
         [0032]    The fan rotor  44  provides air to the main bypass flow B 1  and the core engine flow C. The main bypass flow B 1  flows through the radially inner bypass passage  20  inwardly of a main bypass outer housing  50 , and outwardly of a core engine outer housing  58 . 
         [0033]    The fan rotor  48  provides air to the main bypass flow B 1 , the core engine flow C, and a third stream bypass flow B 2 . The third stream bypass flow B 2  flows through a radially outer bypass passage  24  that is defined inwardly of a third stream bypass outer housing  54  and radially outwardly of the main bypass outer housing  50 . 
         [0034]    Moving axially along the engine  10  in a general direction of flow through the engine  10 , the main bypass outer housing  50  terminates near the end of the turbine section  36 . Terminating the main bypass outer housing  50  in this area permits bypass flows B 1  and B 2  to mix in an area M. 
         [0035]    Referring to  FIG. 2  with continuing reference to  FIG. 1 , the main bypass outer housing  50  begins again in a nozzle portion  60  of the exhaust section  40 . Thus, flow through the nozzle portion  60  is again segregated into a main bypass flow B 1  and a third stream bypass flow B 2 . 
         [0036]    The exhaust section  40  of the example engine  10  includes a flow modulating assembly  62  to manipulate flow through the exhaust section  40  of the engine  10 . The flow modulating assembly  62  includes an upstream flow diverter  64  and a downstream flow diverter  68 . The diverters  64  and  68  manipulate flow within the exhaust section  40  by controlling movement of bypass flows B 1  and B 2  to the core flow C. 
         [0037]    The upstream flow diverter  64  is moveable between a first position and a second position. The upstream flow diverter  64  permits more flow from the bypass flow passages  20  and  24  to move to the core flow passage  26  when in the first position than when in the second position. In some examples, the upstream flow diverter  64  seals an opening  72  within the core engine outer housing  58  when the upstream flow diverter  64  is in the second position. 
         [0038]    The first and second positions for the upstream flow diverter  64  are not singular predefined positions. The first position can, for example, refer to a plurality of possible positions that, relative to other positions, permit more of the flow from the bypass flow passages  20  and  24  to move to the core flow passage  26 . 
         [0039]    The upstream flow diverter  64  is radially aligned with the boundary of the core engine outer housing  58 . The upstream flow diverter  64  includes at least a portion that is axially aligned with a turbine exhaust case  76  of the exhaust section  40 . 
         [0040]    The upstream flow diverter  64  can include several individual diverters distributed about the axis A and positioned circumferentially between vanes  78  of the turbine exhaust case  76 . The upstream flow diverters  64  can be a sliding seal or door. In another example, the upstream flow diverter  64  is a full annular ring extending continuously about the axis and can be radially misaligned with the turbine exhaust case  76 . 
         [0041]    The downstream flow diverter  68  is moveable to a first position and a second position. When the downstream flow diverter  68  is in the first position, the downstream flow diverter  68  permits more flow from the bypass flow passages  20  and  24  to move to the core flow passage  26  than when the downstream flow diverter  68  is in the second position. Bypass flow may move through an opening  80  when entering the core flow passage  26 . 
         [0042]    When in the second position, the downstream flow diverter  68  may effectively seal the opening  80  preventing movement of bypass flow to the core flow passage  26 . Blocking movement of flow through the opening  80  directs more flow through the nozzle portion  60  of the exhaust section  40 . 
         [0043]    The first and second positions for the downstream flow diverter  68  are not singular predefined positions in this example. The first position can, for example, refer to a plurality of possible positions that, relative to other positions, permit more of the flow from the bypass flow passages  20  and  24  to move to the core flow passage  26 . 
         [0044]    When the downstream flow diverter  68  is in the first position, the downstream flow diverter  68  may block bypass flow from entering the nozzle portion  60 . 
         [0045]    The example downstream flow diverter  68  is an annular ring formed of multiple individual flaps that overlap each other circumferentially in a shiplapped manner. The example downstream flow diverter  68  extends continuously about the axis. 
         [0046]    The upstream flow diverter  64  and the downstream flow diverter  68  move axially between the first positions and the second positions. An actuator, such as a pneumatic hydraulic may be used to move the diverters  64  and  68  axially. 
         [0047]    When the upstream flow diverter  64  is in the position of  FIG. 2 , the turbine exhaust case  76  is cooled by bypass flow that has moved from the bypass flow passages  20  and  24  to the core flow passage  26 . Moving the upstream flow diverter  64  aftward to reveal more of the opening  72  can increase bypass flow through the opening  72  to further enhance cooling. 
         [0048]    When the downstream flow diverter  68  is in the position of  FIG. 2 , bypass flow is blocked from moving through the opening  80  to the core flow passage  26 . Instead, the downstream flow diverter  68  directs the bypass flow to the nozzle portion  60 . Directing bypass flow through the nozzle portion  60  enhances cooling of the nozzle portion  60 , which may enhance material durability of components within or near the nozzle portion  60 . 
         [0049]    When the upstream flow diverter  64  is in the position of  FIG. 3 , bypass flow is blocked from moving through the opening  72  to the core flow passage  26 . Instead, the bypass flow moves downstream past the turbine exhaust case  76 . 
         [0050]    When the downstream flow diverter  68  is in the position of  FIG. 3 , flow from the bypass flow passages  20  and  24  can move through the opening  80  and is blocked from entering the nozzle portion  60 . Directing bypass flow through the opening  80  to the core flow passage  26  can provide relatively efficient thrust. 
         [0051]    The positions of the upstream flow diverter  64  and the downstream flow diverter  68  in  FIG. 3  may be most appropriate when the engine is operating at an efficient cruising stage. 
         [0052]    When the upstream flow diverter  64  is in the position of  FIG. 4 , bypass flow is free to move through the opening  72 , which can cool the turbine exhaust case  76 . 
         [0053]    More of the opening  72  is revealed when the upstream flow diverter  64  is in the position of  FIG. 4  than when the upstream flow diverter  64  is in the position of  FIG. 2 . This repositioning of the upstream flow diverter  64  results in more bypass flow directed toward the turbine exhaust case  76  when the upstream flow diverter  64  is in the position of  FIG. 4 , than when the upstream flow diverter  64  is in the position of  FIG. 2 . 
         [0054]    Less bypass flow moves to the nozzle portion  60  when the upstream flow diverter  64  is in the position of  FIG. 4  than when in the position of  FIG. 2 . Thus, positioning the upstream flow diverter  64  in the position of  FIG. 2 , rather than the position of  FIG. 4 , can result in more relative cooling of the components providing the nozzle portion  60 . 
         [0055]    The upstream flow diverter  64  and the downstream flow diverter  68  are independently moveable between the respective first positions and second positions. The upstream flow diverter  64  is axially spaced from the downstream flow diverter  68 . Each of the flow diverters  64  and  68  can cover or uncover separate openings within the engine  10 . 
         [0056]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.