Abstract:
An arrangement of a rotating component and a stationary component of a gas turbine engine includes a rotating component, a stationary component positioned to define an actual gap between the rotating component and the stationary component, and a flow restriction feature formed at one of the stationary component or the rotating component. The flow restriction feature is configured to induce a recirculation flow at the actual gap, thereby defining an effective gap between the rotating component and the stationary component to reduce a leakage flow therebetween, while maintaining the actual gap greater than the effective gap.

Description:
BACKGROUND 
       [0001]    This disclosure relates to gas turbine engines, and more particularly to the prevention of undesirable leakage between rotating components and stationary components of gas turbine engines. 
         [0002]    Ingestion leakage between rotating structures and stationary or static structures of a gas turbine engine are challenging to overcome. If significant amounts of hot gas leak from the flow path of the gas turbine engine to areas outside of the flow path, not only is engine performance degraded, but components outside of the flowpath, which are not constructed to withstand such high temperatures, may be damaged by the hot gas leakage. 
         [0003]    Typical configurations often include shiplap features, in which the static component and rotating component overlap radially and/or axially in an effort to prevent leakage. Such configurations, however, have limited success due to clearance gaps required between the static components and rotating components to prevent contact therebetween during operation of the gas turbine engine. 
       SUMMARY 
       [0004]    In one embodiment, an arrangement of a rotating component and a stationary component of a gas turbine engine includes a rotating component, a stationary component positioned to define an actual gap between the rotating component and the stationary component, and a flow restriction feature formed at one of the stationary component or the rotating component. The flow restriction feature is configured to induce a recirculation flow at the actual gap, thereby defining an effective gap between the rotating component and the stationary component to reduce a leakage flow therebetween, while maintaining the actual gap greater than the effective gap. 
         [0005]    Additionally or alternatively, in this or other embodiments the flow restriction feature is a hook feature formed in the stationary component. 
         [0006]    Additionally or alternatively, in this or other embodiments the hook feature is located at an entrance to the actual gap at a hot gas flowpath of the gas turbine engine. 
         [0007]    Additionally or alternatively, in this or other embodiments the flow restriction feature has a major axis extending substantially parallel to an airflow direction into the flow restriction feature. 
         [0008]    Additionally or alternatively, in this or other embodiments one or more dividing walls are located at the flow restriction feature. 
         [0009]    Additionally or alternatively, in this or other embodiments the one or more dividing walls are configured to restrict circumferential flow through the flow restriction feature. 
         [0010]    In another embodiment, a turbine assembly of a gas turbine engine includes a turbine rotor rotatable about a central axis of the gas turbine engine, a turbine stator located axially adjacent to the turbine rotor defining an actual gap between the turbine rotor and the turbine stator. The turbine stator is configured to be stationary relative to the central axis. A flow restriction feature is formed at the turbine configured to induce a recirculation flow at the actual gap, thereby defining an effective gap between the turbine rotor and the turbine stator to reduce a leakage flow therebetween, while maintaining the actual gap greater than the effective gap. 
         [0011]    Additionally or alternatively, in this or other embodiments the flow restriction feature is a hook feature formed in the stationary component. 
         [0012]    Additionally or alternatively, in this or other embodiments the hook feature is located at an entrance to the actual gap at a hot gas flowpath of the gas turbine engine. 
         [0013]    Additionally or alternatively, in this or other embodiments the flow restriction feature has a major axis extending substantially parallel to an airflow direction into the flow restriction feature. 
         [0014]    Additionally or alternatively, in this or other embodiments one or more dividing walls are located at the flow restriction feature. 
         [0015]    Additionally or alternatively, in this or other embodiments the one or more dividing walls are configured to restrict circumferential flow through the flow restriction feature. 
         [0016]    In yet another embodiment, a gas turbine engine includes a rotating component, a stationary component positioned to define an actual gap between the rotating component and the stationary component and a flow restriction feature formed at one of the stationary component or the rotating component. The flow restriction feature is configured to induce a recirculation flow at the actual gap, thereby defining an effective gap between the rotating component and the stationary component to reduce a leakage flow therebetween, while maintaining the actual gap greater than the effective gap. 
         [0017]    Additionally or alternatively, in this or other embodiments the flow restriction feature is a hook feature formed in the stationary component. 
         [0018]    Additionally or alternatively, in this or other embodiments the hook feature is positioned at an entrance to the actual gap at a hot gas flowpath of the gas turbine engine. 
         [0019]    Additionally or alternatively, in this or other embodiments the flow restriction feature has a major axis extending substantially parallel to an airflow direction into the flow restriction feature. 
         [0020]    Additionally or alternatively, in this or other embodiments one or more dividing walls are located at the flow restriction feature. 
         [0021]    Additionally or alternatively, in this or other embodiments the one or more dividing walls are configured to restrict circumferential flow through the flow restriction feature. 
         [0022]    Additionally or alternatively, in this or other embodiments the rotating component is a turbine rotor. 
         [0023]    Additionally or alternatively, in this or other embodiments the stationary component is a turbine stator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The subject matter which is regarded as the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0025]      FIG. 1  illustrates a schematic cross-sectional view of an embodiment of a gas turbine engine; 
           [0026]      FIG. 2  illustrates a cross-sectional view of another embodiment of a gas turbine engine; 
           [0027]      FIG. 3  illustrates a cross-sectional view of an interface between a rotating component and a stationary component of a gas turbine engine; and 
           [0028]      FIG. 4  illustrates another embodiment of an interface between a rotating component and a stationary component of a gas turbine engine. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  is a schematic illustration of a gas turbine engine  10 . The gas turbine engine generally has includes fan section  12 , a low pressure compressor  14 , a high pressure compressor  16 , a combustor  18 , a high pressure turbine  20  and a low pressure turbine  22 . The gas turbine engine  10  is circumferentially disposed about an engine centerline X. During operation, air is pulled into the gas turbine engine  10  by the fan section  12 , pressurized by the compressors  14 ,  16 , mixed with fuel and burned in the combustor  18 . Hot combustion gases generated within the combustor  18  flow through high and low pressure turbines  20 ,  22 , which extract energy from the hot combustion gases. 
         [0030]    In a two-spool configuration, the high pressure turbine  20  utilizes the extracted energy from the hot combustion gases to power the high pressure compressor  16  through a high speed shaft  24 , and the low pressure turbine  22  utilizes the energy extracted from the hot combustion gases to power the low pressure compressor  14  and the fan section  12  through a low speed shaft  26 . The present disclosure, however, is not limited to the two-spool configuration described and may be utilized with other configurations, such as single-spool or three-spool configurations, or gear-driven fan configurations. 
         [0031]    Gas turbine engine  10  is in the form of a high bypass ratio turbine engine mounted within a nacelle or fan casing  28  which surrounds an engine casing  30  housing an engine core  32 . A significant amount of air pressurized by the fan section  12  bypasses the engine core  32  for the generation of propulsive thrust. The airflow entering the fan section  12  may bypass the engine core  32  via a fan bypass passage  34  extending between the fan casing  28  and the engine casing  30  for receiving and communicating a discharge flow F 1 . The high bypass flow arrangement provides a significant amount of thrust for powering an aircraft. 
         [0032]    The engine casing  30  generally includes an inlet case  36 , a low pressure compressor case  38 , and an intermediate case  40 . The inlet case  36  guides air to the low pressure compressor case  38 , and via a splitter  42  also directs air through the fan bypass passage  34 . 
         [0033]    Referring now to  FIG. 2 , the high pressure compressor  16  includes one or more compressor rotors  44  rotatable about engine centerline X in an axially alternating arrangement with one or more compressor stators  46 , which are rotationally stationary. Similarly, the high pressure turbine  20  and low pressure turbine  22  each include one or more turbine rotors  48  rotatable about engine centerline X in an axially alternating arrangement with one or more turbine stators  50 , which are rotationally stationary. 
         [0034]    Referring now to  FIG. 3 , context of the following description is a high pressure turbine  20  with a turbine rotor  48  and a turbine stator  50 , but one skilled in the art will readily appreciate that the present disclosure may be readily applied to other interface of rotating components with stationary components, such as compressor rotors  44  and compressor stators  46  or the like.  FIG. 3  illustrates an interface of a turbine rotor  48  and a turbine stator  50  at a hot gas flowpath  52  of the gas turbine engine  10 . The interface is configured with a gap  54 , in this embodiment both radial and axial, between the turbine rotor  48  and the turbine stator  50  to prevent contact between the turbine rotor  48  and the turbine stator  50  during operation of the gas turbine engine  10 . This gap  54 , however, can often result in leakage flow from the hot gas flowpath  52  through the gap  54 , which can reduce performance of the gas turbine engine  10  and even cause damage to components not configured to withstand temperatures of leakage from the hot gas flowpath  52 . Further, the gap  54  can result in leakage flow from outside of the hot gas flowpath  52  through the gap  54  into the hot gas flowpath  52 . 
         [0035]    To prevent such leakage through the gap  54  either into or out of the hot gas flowpath  52 , the turbine stator  50  includes a hook feature  56 . In some embodiments, such as shown in  FIG. 3 , the hook feature  56  is a recess or notch formed in the turbine stator  50 . The hook feature  56  may be located at a gap entrance  58  of the gap  54  at the hot gas flowpath  52  as shown in  FIG. 3 , or in other embodiments may be located at other locations along the gap  54  between the turbine rotor  48  and the turbine stator  50 . The hook feature  56  extends at least partially around a circumference of the hot gas flow path  52 , relative to the engine centerline X. In some embodiments, the hook feature  56  may extend continuously about the engine centerline X, while in other embodiments a plurality of hook features  56  may each extend partially about the engine centerline X. While in the embodiments described herein the hook features  56  are located at turbine stator  50 , in other embodiments the hook features  56  may additionally or alternatively be located at the turbine rotor  48 . 
         [0036]    The hook feature  56  is configured to allow an airflow  60  from the hot gas flowpath  52  into the hook feature  56 , which results in a recirculation flow  62  at least partially in the hook feature  56 , and in some embodiments extending to outside of the hook feature  56 . The recirculation flow  62  narrows an effective gap  64  between the turbine rotor  48  and the turbine stator  50  thus restricting airflow from the hot gas path  52  from flowing through the gap  54 . In some embodiments, the hook feature  56  is curvilinear and has a major axis  66 . The major axis  66  is substantially aligned with the airflow  60  to maximize the recirculation flow  62 . 
         [0037]    Referring now to  FIG. 4 , in some embodiments one or more dividing walls  68  are located in the hook feature  56  to divide the hook feature  56  into a plurality of circumferential compartments  70 . The circumferential pockets  70  are configured to prevent circumferential leakage flows. 
         [0038]    Utilizing the hook feature  56  results in a non-contact flow restriction via the recirculation flow  60 , which reduces the effective gap  62  between the turbine rotor  48  and the turbine stator  50 . The recirculation flow  60  reduces leakage via reduction of the effective gap  62  while still allowing the actual gap  54  between the turbine rotor  48  and the turbine stator  50  to be large enough to provide adequate operational clearance so contact between the turbine rotor  48  and the turbine stator  50  is avoided during operation of the gas turbine engine. 
         [0039]    While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.