Abstract:
One embodiment of the present disclosure is a unique system. Another embodiment is a unique fastener system. Another embodiment is a unique gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines, fastener systems and other systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/747,733, filed 31 Dec. 2012, the disclosure of which is now expressly incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to thermally tunable systems. More particularly, in some embodiments, the present disclosure relates to thermally tunable fastener systems. 
       BACKGROUND 
       [0003]    Fastener systems that exhibit a desirable thermal response remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
       SUMMARY 
       [0004]    One embodiment of the present disclosure is a unique system. Another embodiment is a unique fastener system. Another embodiment is a unique gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines, fastener systems and other systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0006]      FIG. 1  schematically depicts some aspects of a non-limiting example of a gas turbine engine in accordance with an embodiment of the present disclosure; and 
           [0007]      FIG. 2  illustrates some aspects of a non-limiting example of a tunable fastener system in accordance with an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    For purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the disclosure is intended by the illustration and description of certain embodiments of the disclosure. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present disclosure. Further, any other applications of the principles of the disclosure, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the disclosure pertains, are contemplated as being within the scope of the present disclosure. 
         [0009]    Referring to the drawings, and in particular  FIG. 1 , some aspects of a non-limiting example of an engine  10  in accordance with an embodiment of the present disclosure are schematically depicted. In one form, engine  10  is a gas turbine engine. Engine  10  includes a compressor system  12 , a combustion system  14  in fluid communication with compressor system  12 , and a turbine system  16  in fluid communication with combustion system  14 . In one form, compressor system  12 , combustion system  14  and turbine system  16  are disposed about an engine centerline  18 , e.g., the axis of rotation of compressor system  12  and turbine system  16 . In other embodiments, other arrangements may be employed. In various embodiments, engine  10  may or may not have a compressor system and/or a turbine system, or may have additional turbomachinery components in addition to a compressor system and/or a turbine system. In some embodiments, engine  10  may be a direct propulsion engine that produces thrust directly from combustion system  14 . In other embodiments, combustion system  14  may form a gas generator for a gas turbine propulsion system, or may be employed in a gas turbine engine topping cycle. In still other embodiments, engine  10  may be one or more of other types of gas turbine engines, hybrid engines, and/or combined cycle engines. 
         [0010]    Attached to turbine system  16  is a tailcone  20 . In one form, tailcone  20  is secured to turbine system  16  via a thermally tunable fastener (tiebolt) system  22 . In other embodiments, a plurality of fastener systems  22  may be employed to secure tailcone  20  to turbine system  16 . In one form, tailcone  20  is a rotating monolithic ceramic tailcone. In other embodiments, tailcone  20  may be stationary. In various embodiments, tailcone  20  may be formed from any metallic, intermetallic, ceramic, or composite material. Tailcone  20  is expected to experience thermal growth as its temperature increases from ambient temperature, e.g., from sea level static standard day conditions, to some predetermined engine  10  design point or other operating point temperature. The thermal growth of typical fasteners is typically about twice the thermal growth of tailcone  20 , e.g., depending upon the materials used in construction of the fastener and of tailcone  20 , and the temperature differential(s) experienced during operation relative to ambient temperature. Hence, with the use of conventional fasteners, there may be a tendency of tailcone  20  to become loose during operation, owing to the relative thermal expansion between tailcone  20  and the conventional fasteners. 
         [0011]    Referring now to  FIG. 2 , in conjunction with  FIG. 1 , some aspects of a non-limiting example of fastener system  22  in accordance with an embodiment of the present disclosure is depicted. Fastener system  22  is a thermally tunable fastener system, e.g., tunable by selection of materials used to form fastener system  22 . Fastener system  22  includes a member  24 , a member  26 , and a member  28 . In one form, member  24  is an elongated cylindrical core shaft, member  26  is an elongated cylindrical inner shell, and member  28  is an elongated cylindrical outer shell. In other embodiments, one or more of members  24 ,  26  and  28  may take other forms, e.g., shapes other than cylindrical and/or elongate. In one form, member  24  is solid, e.g., not hollow. In other embodiments, member  24  may include one or more passages extending therethrough, and/or may be hollow, e.g., to permit the passage of one or more fluids, e.g., cooling air, to pass therethrough. 
         [0012]    Member  24  includes a body  30 , an attachment feature  32 , and an interface feature  34 . Attachment feature  32  is configured to attach member  24  to an attachment location  36  on turbine system  16 , e.g., a final turbine rotor stage (not shown). In one form, attachment feature  32  is an externally threaded portion of member  24 . In other embodiments, one or more other attachment mechanism types may be employed in addition to or in place of threads. In one form, interface feature  34  is a shoulder formed into the aft end of member  24 , and is configured to interface with a corresponding interface feature on member  26 . In other embodiments, interface feature  34  may take other geometric forms suitable for interfacing with a corresponding interface feature on member  26  and for transmitting axial loads between member  24  and member  26 . The location of interface feature  34  on member  24  may vary with the needs of the particular application. Member  24 , in particular, body  30 , has a coefficient of thermal expansion α 1 . 
         [0013]    Member  26  includes a body  40 , an interface feature  42 , and an interface feature  44 . Interface feature  42  and interface feature  34  are configured for engagement with each other, and are configured to transmit axial loads between member  24  and member  26 . In one form, interface features  42  and  44  are in the form of end walls of member  26 . In other embodiments, one or both of interface features  42  and  44  may take other forms in addition to or in place of end walls of member  26 , and may be located in accordance with the needs of the particular application. Member  26 , in particular body  40 , has a coefficient of thermal expansion α 2  that is higher (greater) than coefficient of thermal expansion al of member  24 . 
         [0014]    Member  28  includes a body  50 , an attachment feature  52 , and an interface feature  54 . Attachment feature  52  is configured to attach member  28  to an attachment location  56  on tailcone  20 . In one form, attachment feature  52  is an externally threaded portion of member  28 . In other embodiments, one or more other attachment mechanism types may be employed in addition to or in place of threads. System  22  is configured to secure attachment location  36  to attachment location  56 , e.g., to secure tailcone  20  to turbine system  16 . In one form, interface feature  54  is an internal shoulder of member  28 . In other embodiments, interface feature  54  may take one or more other forms in addition to or in place of an internal shoulder of member  28 , and may be located in accordance with the needs of the particular application. Interface feature  54  and interface feature  44  are configured for engagement with each other, and are configured to transmit axial loads between member  26  and member  28 . Member  28 , in particular body  50 , has a coefficient of thermal expansion α 3  that is lower than coefficient of thermal expansion α 2  of member  26 . In other embodiments, the coefficient of expansion, α 3 , may be greater than, including substantially greater than the coefficient of thermal expansion α 2  of member  26 . 
         [0015]    An axis  60  extends between attachment feature  32  and attachment feature  52 . In one form, axis  60  is a longitudinal axis of fastener system  22 . In one form, members  24 ,  26  and  28 , and in particular, bodies  30 ,  40  and  50  are bodies of revolution centered on axis  60 , e.g., cylindrical shafts. In other embodiments, members  24 ,  26  and  28 , bodies  30 ,  40  and  50  may not be bodies of revolution, and/or may not be centered on axis  60 . 
         [0016]    In one form, member  24  is disposed proximate to member  26 ; and member  26  is disposed proximate to member  28 . In a particular form, body  30  is nested within body  40 ; and body  40  is nested within body  50 . In some embodiments, one or more anti-rotation schemes may be employed to limit the rotation of one or members  24 ,  26  and  28  relative to one or more others of members  24 ,  26  and  28 . In other embodiments, members  24 ,  26  and  28 , and bodies  30 ,  40  and  50  may take other forms. For example, in some embodiments, one or more of members  24 ,  26 , and  28  and/or one or more of bodies  30 ,  40 , and  50  may be in the form of metallic sheets or plates, e.g., that are sandwiched together. 
         [0017]    In one form, members  24 ,  26 , and  28  are configured for relative sliding motion as with respect to each other along axis  60 , e.g., as the temperature of system  22  changes, thereby changing the lengths of members  24 ,  26 , and  28  relative to each other. In particular, members  24  and  28  are configured for relative sliding motion as with respect to each other along axis  60 , e.g., as the temperature of system  22  changes, which has a greater effect on member  26  owing to its higher coefficient of thermal expansion than those of members  24  and  28 , thus imparting relative motion between members  24  and  28  with changes in temperature of system  22 . 
         [0018]    When system  22  is in the installed condition, attachment feature  32  is attached to attachment location  36 , e.g., on turbine system  16 ; and attachment feature  52  is attached to attachment location  56 , e.g., on tailcone  20 . In one form, when system  22  is installed, members  24  and  28  are loaded in tension, whereas member  26  is loaded in compression. In one form, as the temperature of system  22  increases, e.g., to an operating temperature consistent with engine  10  operation, the coefficient of thermal expansion α 2  of member  26 , being higher than that of members  24  and  28 , yields higher thermal growth in member  26  than in members  24  and  28 , and loads member  26  in compression and members  24  and  28  in tension. Although thermal growth of members  24  and  28  tends to increase the overall dimension of system  22 , e.g., as measured between attachment features  32  and  52 , the thermal growth of member  26  tends toward decreasing the overall dimension of system  22 , that is, tends to drive attachment features  32  and  52  closer together. System  22  may thus be tuned, by virtue of material selection to yield desired coefficients of expansion α 1 , α 2 , and α 3 , and by the length of members  24 ,  26 , and  28  as between their respective interface features  34 ,  42 ,  44 , and  54  to increase, decrease, or maintain a desired axial distance between attachment features  32  and  52  with increasing temperature and at a desired operating temperature. Hence, system  22  may be tuned, e.g., to match the thermal growth of tailcone  20  to reduce thermal loading upon tailcone  20  during the operation of engine  10 , or to achieve some desired loading condition in system  22  and tailcone  20  during operation of engine  10 , e.g., at a desired operating temperature. 
         [0019]    In other embodiments, system  22  may or may not be a fastener, and may be configured to, for example and without limitation, position or reposition one or more components and/or portions of components. For example, one or both of attachment features  32  and  52  may be configured as abutment features configured for transmitting load and/or motion between the core shaft and a first structure, and between the outer shaft and a second structure. In one form, such embodiments may be configured to position the first structure and the second structure relative to each other, e.g., by translating and/or rotating one or both of the first structure and the second structure, in response to a change in temperature of system  22 . 
         [0020]    In some embodiments, the coefficients of thermal expansion, α 1 , α 2 , and/or α 3  may be selected so that system  22  expands in length with increasing temperature faster than other metals, slower than other metals, or faster or slower than other engineering materials, e.g., composite materials. The relative positioning of the first structure and the second structure in response to the change in temperature may provide the basis of operation of one or more systems or devices. For example, in one embodiment, one or more systems  22  may be coupled to a valve system, and may operate a conventional valve or a fluidic valve to increase or decrease flow and/or alter flow direction by displacing one or more components of the valve in response to a change in temperature using system(s)  22 . In various embodiments, system  22  may be configured to shift or position surfaces or other features axially and/or radially in response to changes in temperature of system  22 . Some embodiments may include shifting the axial position of and/or radially deflect an aircraft and/or engine inlet component or a tailcone or exhaust system component, e.g., an exhaust mixer, in order to vary the flowpath area or throat area. 
         [0021]    In some embodiments, system  22  may be arranged in a stacked configuration, e.g., using a plurality of one or more of members  24 ,  26 , and  28  arranged in series, in order to increase the output of system  22 , e.g., the displacement. In some embodiments, one or more systems  22  may be configured to displace an inner or outer band within the engine, rotate or shift one or more airfoils or rows of airfoils, and/or may be configured to drive a wedge, a lever, or any other mechanism to position, fasten, bend, or otherwise affect in a direction the same as or other than the mechanism&#39;s direction of action. In some embodiments, the actuating power of system  22  or modifications thereof could axially deflect the end of a specially-designed tailcone, e.g., a metallic tailcone, to cause it to expand radially, closing a throat for example. 
         [0022]    Embodiments of the present disclosure include a system for securing a first attachment location to a second attachment location. The system includes having a first member, a second member, and a third member. The first member having a first coefficient of thermal expansion, a first attachment feature, and a first interface feature. The first attachment feature is configured for attaching the first member to the first attachment location. The second member has a second coefficient of thermal expansion that is higher than the first coefficient of thermal expansion. The second member has a second interface feature and a third interface feature. The first interface feature and the second interface feature are configured for engagement with each other and are configured to transmit an axial load between the first member and the second member. The third member has a third coefficient of thermal expansion that is lower than the second coefficient of thermal expansion, a second attachment feature, and a fourth interface feature. The second attachment feature is configured to attach the third member to the second attachment location. The fourth interface feature and the third interface feature are configured for engagement with each other, and are configured to transmit the axial load between the second member and the third member. 
         [0023]    In a refinement, in an installed condition, the first attachment feature is attached to the first attachment location. The second attachment feature is attached to the second attachment location. In the installed condition, the first member and the third member are loaded in tension and the second member is loaded in compression. 
         [0024]    In another refinement, in an installed condition, the first attachment feature is attached to the first attachment location. The second attachment feature is attached to the second attachment location. In the installed condition and at an operating temperature, the first member and the third member are loaded in tension. In the installed condition at the operating temperature, the second member is loaded in compression. 
         [0025]    In yet another refinement, the first member, the second member, and the third member are arranged in a relationship wherein the second member is disposed proximate the first member and the third member is disposed proximate the second member. In still another refinement, the first member includes a first member body, the second member includes a second member body, and the third member includes a third member body. 
         [0026]    In yet still another refinement, at least one of the first member body, the second member body, and the third member body are cylindrical shafts. In a further refinement, the first member body is nested within the second member body and the second member body is nested within the third member body. 
         [0027]    In a yet further refinement, the first member and the third member are configured for relative sliding motion as with respect to each other along a longitudinal axis of the system. In a still further refinement, the first member and the third member are configured for sliding relative motion as with respect to each other along an axis extending between the first attachment feature and the second attachment feature. 
         [0028]    Embodiments of the present disclosure include a system for positioning a first structure relative to a second structure, comprising: a core shaft, an inner shell, and an outer shell. The core shaft has a first coefficient of thermal expansion, a first abutment feature, and a first interface feature. The first abutment feature is configured for transmitting load between the core shaft and the first structure. 
         [0029]    The inner shell has a second coefficient of thermal expansion that is different than the first coefficient of thermal expansion, a second interface feature, and a third interface feature. The first interface feature and the second interface feature are configured for engagement with each other and are configured to transmit an axial load between the core shaft and the inner shell. 
         [0030]    The outer shell has a third coefficient of thermal expansion that is different than the second coefficient of thermal expansion, a second abutment feature, and a fourth interface feature. The second abutment feature is configured for transmitting load between the outer shell to the second structure. The fourth interface feature and the second interface feature are configured for engagement with each other and are configured to transmit the axial load between the inner shell and the outer shell. 
         [0031]    In a refinement, the first, second, and third coefficients of thermal expansion are selected to increase an axial distance between the first abutment feature and the second abutment feature with increasing temperature. In another refinement, the first, second, and third coefficients of thermal expansion are selected to maintain an axial distance between the first abutment feature and the second abutment feature with increasing temperature. 
         [0032]    In yet another refinement, the first, second, and third coefficients of thermal expansion are selected to decrease an axial distance between the first abutment feature and the second abutment feature with increasing temperature. In still another refinement, the first, second, and third coefficients of thermal expansion are selected to achieve a desired axial distance between the first abutment feature and the second abutment feature at a desired operating temperature. 
         [0033]    In a yet still another refinement, the core shaft and the outer shell are configured for sliding relative motion as with respect to each other along a longitudinal axis of the system. In a further refinement, the core shaft is not hollow. 
         [0034]    In a yet further refinement, the inner shell is disposed within the outer shell. The core shaft is disposed within the inner shell. 
         [0035]    In a still further refinement, in an installed condition, the first abutment feature is couple to the first structure and the second abutment feature is coupled to the second structure. In the installed condition, the outer shell and the core shaft are loaded in tension and the inner shell is loaded in compression. 
         [0036]    In a yet still further refinement, in an installed condition, the first abutment feature is attached to the first structure and the second abutment feature is attached to the second structure. In the installed condition and at an operating temperature, the core shaft and the outer shell are loaded in tension. In the installed condition at the operating temperature, the inner shell is loaded in compression. 
         [0037]    Embodiments of the present invention include a gas turbine engine, comprising: a fastener system, including: a first attachment feature; a second attachment feature spaced apart from the first attachment feature; and means for coupling the first attachment feature and the second attachment feature. The means for coupling is tunable to achieve a desired change in a distance between the first attachment feature and the second attachment feature with a change in temperature of the fastener system. 
         [0038]    While the disclosure has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the disclosure is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the disclosure, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.