Abstract:
Aspects of the disclosure are directed to a seal comprising: a first leg that emanates from a center point of the seal and is configured to contact a first component, a second leg that emanates from the center point and is configured to contact a second component that is operative at a temperature that is within a range of 648 degrees Celsius to 1093 degrees Celsius, and a third leg that emanates from the center point.

Description:
BACKGROUND 
       [0001]    Gas turbine engines, such as those which power aircraft and industrial equipment, employ a compressor to compress air that is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture. Referring to  FIG. 2A , the fuel-air mixture may form part of a primary/core flow  202  and may be used to generate thrust. The products of combustion may be at elevated temperatures, which may cause the turbine components to see temperatures as hot as 2000 degrees Fahrenheit (approximately 1093 degrees Celsius). 
         [0002]    At least a portion of one or more secondary flows (denoted in  FIG. 2A  by arrows  208 ) may provide cooling air to turbine components. The air  208  may be sourced from, e.g., the compressor. Since the amount of air  208  diverted to provide cooling impacts the performance/efficiency of an engine, seals (see  FIG. 2B —seal  254 ) are incorporated as part of a secondary flow system to reduce (e.g., minimize) leakage. 
         [0003]    Referring to  FIG. 2B , a conventional two-point axial ring seal  254  is shown. The seal  254  is commonly referred to as a dog-bone seal and operates as a mechanical, non-linear spring. An axial interference fit is provided between the seal  254  and adjacent components (e.g., component  258 ), which causes the seal to be subject to a rolling motion. For example, the ends  254   a  and  254   b  of the seal  254  may be subject to a rolling motion, where the end  254   a  may be urged aft and the end  254   b  may be urged forward in  FIG. 2B . As the two ends  254   a  and  254   b  deflect elastically to new locations (e.g., new diameters), hoop stress is introduced which acts in a restorative manner. For example, elastic restorative forces imposed on the ends  254   a  and  254   b  are shown via arrows  264   a  and  264   b , respectively. 
         [0004]    Ideally, the seal  254  maintains contact with the adjacent components (e.g., the component  258 , component  268 ) despite axial motion and a pressure differential that urges the seal  254  to lose contact with the components. For example, a pressure load  270  may be imposed on the seal  254 , where the load  270  is a result of the secondary flows  208  being at an elevated pressure. 
         [0005]    Given that the seal  254  is often in contact with extremely hot components, such as for example at the interface between the end  254   b  and the component  258 , the functional or structural integrity of the seal  254  may be compromised due to creep. Creep occurs when the material of the seal  254  is subjected to elevated stress (e.g., elevated temperature) for extended periods of time. Creep causes the material of the seal  254  to permanently deform (based on the deflected state/position that the seal  254  assumes), even when the magnitude of the stress is below the material&#39;s yield strength. Creep degrades the seal  254 &#39;s ability to withstand the load  270  over time, which can cause the seal  254  (e.g., the end  254   b ) to lose contact with an adjacent component (e.g., the component  258 ). 
       BRIEF SUMMARY 
       [0006]    The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosure. The summary is not an extensive overview of the disclosure. It is neither intended to identify key or critical elements of the disclosure nor to delineate the scope of the disclosure. The following summary merely presents some concepts of the disclosure in a simplified form as a prelude to the description below. 
         [0007]    Aspects of the disclosure are directed to a seal comprising: a first leg that emanates from a center point of the seal and is configured to contact a first component, a second leg that emanates from the center point and is configured to contact a second component that is operative at a temperature that is within a range of 648 degrees Celsius to 1093 degrees Celsius, and a third leg that emanates from the center point. In some embodiments, the first leg has a first length, the second leg has a second length, and the third leg has a third length. In some embodiments, the third length is at least 10% of at least one of the first length or the second length. In some embodiments, the seal further comprises a fourth leg that emanates from the center point. In some embodiments, the fourth leg has a fourth length, and a summation of the third length and the fourth length is at least 10% of at least one of the first length or the second length. In some embodiments, the third leg is separated from each of the first leg and the second leg by approximately 90 degrees. In some embodiments, the fourth leg is separated from each of the first leg and the second leg by approximately 90 degrees. In some embodiments, the third leg is separated from each of the first leg and the second leg by approximately 90 degrees. In some embodiments, the seal includes a nickel alloy. 
         [0008]    Aspects of the disclosure are directed to an engine comprising: a compressor section, a combustor section axially downstream of the compressor section, a turbine section axially downstream of the combustor section, the turbine section including a first component and a second component, and a seal incorporated in the turbine section, the seal including: a first leg that emanates from a center point of the seal, the first leg contacting the first component, a second leg that emanates from the center point, the second leg contacting the second component, and a third leg that emanates from the center point. In some embodiments, the second component is configured to operate at a temperature that is within a range of 648 degrees Celsius to 1093 degrees Celsius. In some embodiments, the second component includes a blade outer air seal support. In some embodiments, the first component includes an outer case. In some embodiments, the seal is configured to interface to a pressure load. In some embodiments, the pressure load includes air sourced from the compressor section. In some embodiments, the first leg has a first length, the second leg has a second length, and the third leg has a third length. In some embodiments, the third length is at least 10% of at least one of the first length or the second length, and the third length is less than 200% of each of the first length and the second length. In some embodiments, the engine comprises a fourth leg that emanates from the center point. In some embodiments, the fourth leg has a fourth length, and a summation of the third length and the fourth length is at least 10% of at least one of the first length or the second length, and the summation of the third length and the fourth length is less than 200% of each of the first length and the second length. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. The drawings are not necessarily drawn to scale unless specifically indicated otherwise. 
           [0010]      FIG. 1  is a side cutaway illustration of a geared turbine engine. 
           [0011]      FIG. 2A  illustrates a portion of a prior art engine incorporating a primary flow and cooling air. 
           [0012]      FIG. 2B  illustrates a prior art seal. 
           [0013]      FIG. 3  illustrates a cross-section of a turbine section of an engine. 
           [0014]      FIGS. 4-5  illustrate seals that may be incorporated as part of an engine in accordance with aspects of this disclosure. 
           [0015]      FIG. 6A  illustrates a full-hoop arrangement associated with a seal in accordance with aspects of this disclosure. 
           [0016]      FIG. 6B  illustrates a section of the full-hoop arrangement of  FIG. 6A  with the cross-section of the seal of  FIG. 4  visible. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. 
         [0018]    In accordance with aspects of the disclosure, apparatuses, systems, and methods are directed to a creep resistant axial ring seal. The seal may include three or more full-ring features that emanate from a center of cross-sectional rotation. Creep may occur at a first of the features (e.g., a contact interface between the seal and another component), whereas the other features may provide rolling resistance and resistance to load (e.g., pressure load). 
         [0019]    Aspects of the disclosure may be applied in connection with a gas turbine engine.  FIG. 1  is a side cutaway illustration of a geared turbine engine  10 . This turbine engine  10  extends along an axial centerline  12  between an upstream airflow inlet  14  and a downstream airflow exhaust  16 . The turbine engine  10  includes a fan section  18 , a compressor section  19 , a combustor section  20  and a turbine section  21 . The compressor section  19  includes a low pressure compressor (LPC) section  19 A and a high pressure compressor (HPC) section  19 B. The turbine section  21  includes a high pressure turbine (HPT) section  21 A and a low pressure turbine (LPT) section  21 B. 
         [0020]    The engine sections  18 - 21  are arranged sequentially along the centerline  12  within an engine housing  22 . Each of the engine sections  18 - 19 B,  21 A and  21 B includes a respective rotor  24 - 28 . Each of these rotors  24 - 28  includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s). 
         [0021]    The fan rotor  24  is connected to a gear train  30 , for example, through a fan shaft  32 . The gear train  30  and the LPC rotor  25  are connected to and driven by the LPT rotor  28  through a low speed shaft  33 . The HPC rotor  26  is connected to and driven by the HPT rotor  27  through a high speed shaft  34 . The shafts  32 - 34  are rotatably supported by a plurality of bearings  36 ; e.g., rolling element and/or thrust bearings. Each of these bearings  36  is connected to the engine housing  22  by at least one stationary structure such as, for example, an annular support strut. 
         [0022]    During operation, air enters the turbine engine  10  through the airflow inlet  14 , and is directed through the fan section  18  and into a core gas path  38  and a bypass gas path  40 . The air within the core gas path  38  may be referred to as “core air”. The air within the bypass gas path  40  may be referred to as “bypass air”. The core air is directed through the engine sections  19 - 21 , and exits the turbine engine  10  through the airflow exhaust  16  to provide forward engine thrust. Within the combustor section  20 , fuel is injected into a combustion chamber  42  and mixed with compressed core air. This fuel-core air mixture is ignited to power the turbine engine  10 . The bypass air is directed through the bypass gas path  40  and out of the turbine engine  10  through a bypass nozzle  44  to provide additional forward engine thrust. This additional forward engine thrust may account for a majority (e.g., more than 70 percent) of total engine thrust. Alternatively, at least some of the bypass air may be directed out of the turbine engine  10  through a thrust reverser to provide reverse engine thrust. 
         [0023]      FIG. 1  represents one possible configuration for an engine  10 . Aspects of the disclosure may be applied in connection with other environments, including additional configurations for gas turbine engines. Aspects of the disclosure may be applied in connection with non-geared engines. 
         [0024]    Referring to  FIG. 3 , a turbine section  300  of an engine is shown. The turbine section  300  may correspond to the high pressure turbine (HPT) section  21 A of the engine  10  of  FIG. 1 . Proceeding in a forward-to-aft manner in  FIG. 3 , the turbine section  300  is shown as including a first stage vane  302 , a first stage blade outer air seal (BOAS)/BOAS support  308 , a second stage vane  314 , and a second stage BOAS/BOAS support  320 . An outer case  326  may provide structural support for the vanes  302  and  314  and the BOAS/BOAS supports  308  and  320 . A seal may be incorporated as part of one or more portions of the turbine section  300 . For example, a seal may be incorporated as part of the BOAS/BOAS supports  308  and  320 . 
         [0025]      FIG. 4  illustrates an example of a seal  454  that may be included as part of the turbine section  300  of  FIG. 3 . The seal  454  may be a full-hoop/full-ring structure (see, e.g.,  FIG. 6A ), a cross-section of which is shown in  FIGS. 4 and 6B . 
         [0026]    The seal  454  may include at least three legs, denoted in  FIG. 4  via reference characters  466   a ,  466   b , and  466   c . The legs  466   a - 466   c  may emanate from a center point  472  of the seal  454 . The legs  466   a ,  466   b , and  466   c  may terminate at ends  454   a ,  454   b , and  454   c , respectively. 
         [0027]    The end  454   a  may contact/interface to a component  466  and the end  454   b  may contact/interface to a component  458 . Much like the component  258  of  FIG. 2B , the component  458  may operate at elevated temperatures [in some embodiments, temperatures within a range of 1200 degrees Fahrenheit to 2000 degrees Fahrenheit (approximately 648 degrees Celsius to 1093 degrees Celsius)], such that the material of the seal  454  at the end  454   b  may creep. Conventionally, such creep might compromise the integrity/functionality of a seal in the manner described above because this “hot” portion of the seal is needed for stiffness to resist/counter a load (e.g., a pressure load  470 ). However, other features of the seal  454  may provide stiffness against the load  470 . For example, the leg  466   c  may be cooler than the leg  466   b  because the leg  466   c  might not be in contact with the component  458 . As such, the leg  466   c  provides stiffness to counter the load  470 . Moreover, the sealing contacts are maintained at the end  454   a  with the component  468  and the end  454   b  with the component  458 . 
         [0028]    As measured relative to the center point  472  and the ends  454   a - 454   c , the leg  466   a  may have a length equal to L a , the leg  466   b  may have a length L b , and the leg  466   c  may have a length equal to L c , respectively. The lengths L a  and L b  may be approximately equal. The length L c  may be equal to at least one of the lengths L a  and L b . For example, in embodiments where the lengths L a , L b , and L c  are approximately equal to one another the hoop stresses may be equal in the legs  466   a ,  466   b , and  466   c  (at least to a first order approximation). In some embodiments, the length L c  may be equal to at least a fraction/percentage of at least one of the lengths L a  or L b . For example, the length L c  may be at least 10% of one of the lengths L a  or L b . The length L c  may be less than 200% of at least one of the lengths L a  or L b . 
         [0029]    In  FIG. 4 , the leg  466   c  is shown as being oriented at approximately 90 degrees relative to each of the legs  466   a  and  466   b . The legs  466   a  and  466   b  may emanate from the center point  472  in substantially opposite directions, thereby forming an approximate angle of 180 degrees between the legs  466   a  and  466   b . The arrangement of the legs  466   a - 466   c  in terms of the angular separations of the legs  466   a - 466   c  is illustrative; other angular values or patterns for the seal  454  may be used. 
         [0030]      FIG. 5  illustrates a seal  554  that may be used in some embodiments. The seal  554  is shown as including the legs  466   a - 466   c  emanating from the center point  472  similar to the seal  454 . However, the seal  554  also may include another (e.g., fourth) leg  566   d  that emanates from the center point  472  and terminates at an end  554   d . The leg  566   d  may have a length L d  as measured between the center point  472  and the end  554   d . Referring to  FIGS. 4 and 5 , a summation of the lengths L c  and L d  may be equal to at least a fraction/percentage of at least one of the lengths L a  or L b . For example, the summation of the lengths L c  and L d  may be at least 10% of at least one of the lengths L a  or L b . The summation of the lengths L c  and L d  may be less than 200% of at least one of the lengths L a  or L b . 
         [0031]    In  FIG. 5 , each of the legs  466   a - 466   c  and the leg  566   d  are shown as being oriented at an angle that is approximately 90 degrees relative to the adjacent legs. The arrangement of the legs  466   a - 466   c  and  566   d  in terms of the angular separations of the legs  466   a - 466   c  and  566   d  is illustrative; other angular values or patterns for the seal  554  may be used. 
         [0032]    A seal (e.g., the seal  454  or the seal  554 ) may be manufactured of one or more materials. For example, the seal may include nickel alloy, Inconel® 718 alloy, etc. 
         [0033]    Technical effects and benefits of this disclosure include a seal that has an enhanced lifetime relative to a conventional seal, where the useable lifetime of the seal is based on the seal&#39;s ability to withstand a load (e.g., pressure load). Creep may occur at an interface where the seal contacts a component that is operating at elevated temperatures. Other features/points of the seal may provide stiffness to the load while still enabling the seal to maintain contact with one or more adjacent components. Seals in accordance with this disclosure may consume substantially the same footprint as a conventional seal, thereby allowing for the replacement of conventional seals on legacy platforms without a need to redesign the layout of the legacy platforms. Seals in accordance with this disclosure may be incorporated in closer proximity to a primary/core flow path and/or the first stage of a turbine section relative to conventional seals due to the thermal characteristics associated with the seals of this disclosure. 
         [0034]    Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional in accordance with aspects of the disclosure. One or more features described in connection with a first embodiment may be combined with one or more features of one or more additional embodiments.