Abstract:
One embodiment of the present invention is a unique turbomachinery device, a non-limiting example of which is a gas turbine engine. Another embodiment is a unique vane assembly for a turbomachinery device. Another embodiment is a unique seal assembly for a vane of a turbomachinery device. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for turbomachinery devices, and for vane assemblies and seal assemblies for turbomachinery devices. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application 61/290,431, filed Dec. 28, 2009, and is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to turbomachinery, and, more particularly, to a rotatable vane having a self adjusting seal configured to seal the gap between an end of the vane and the surface of an adjacent structure. 
     BACKGROUND 
     Gas turbine engines, gas turbine engine vane assemblies, and the sealing of rotatable gas turbine engine vanes, 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 
     One embodiment of the present invention is a unique turbomachinery device, a non-limiting example of which is a gas turbine engine. Another embodiment is a unique vane assembly for a turbomachinery device. Another embodiment is a unique seal assembly for a vane of a turbomachinery device. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for turbomachinery devices, and for vane assemblies and seal assemblies for turbomachinery devices. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically depicts a non-limiting example of a turbomachinery device in accordance with an embodiment of the present invention. 
         FIG. 2  is a partial cross sectional side elevation view depicting a vane positioned adjacent surrounding structures. 
         FIG. 3  is an illustrative side elevation view of a non-limiting example of a rotatable vane with a vane end seal assembly in accordance with an embodiment of the present invention, shown in an exploded (uninstalled) view. 
         FIG. 4  is a partial cross sectional side elevation view depicting the vane and end seal assembly of  FIG. 3  in the installed condition. 
         FIG. 5  depicts an exploded perspective view of a non-limiting example of an embodiment of the present invention that includes a seal retention feature. 
         FIG. 6  depicts another exploded perspective view of the embodiment of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of promoting an understanding of the principles of the invention, 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 invention is intended by the illustration and description of certain embodiments of the invention. 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 invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
     The present invention was developed for application in the field of turbomachinery, including, but not limited to, gas turbine engines, steam turbine engines, other turbines and compressors, engine-driven fans, variable nozzles, and thrust vectoring devices, etc., that employ rotatable vanes, i.e., vanes that rotate in order to modify the flow of the working fluid, including the flow quantity and/or flow direction. As used herein, it will be understood that the term, “rotatable vane,” pertains to a vane that may be rotated about an axis that extends approximately in the span-wise direction of the vane but is otherwise stationary, as opposed to blades, e.g., compressor and/or turbine blades, which continually rotate about an axis that is approximately perpendicular to the span-wise direction of the blade. 
     The output of a turbomachinery device can be enhanced and/or controlled by incorporating one or more stages of rotatable vanes, such as, for example, variable area fan, compressor, turbine and/or vanebox nozzle vanes, which can be rotated in a controlled manner to modify the flow of the working fluid during operation of the turbomachinery device. Rotatable vanes are disposed in proximity with and move relative to adjacent structures, such as flowpath walls, and may rotate between minimum and maximum flow positions to regulate flow of the working fluid. In order to prevent undesirable contact between the adjacent structures and the end portions of the vane, e.g., vane tips and/or roots, a gap is typically provided between the vane tip and adjacent structure, and between the vane root and adjacent structure. However, such gaps yield undesirable “end wall leakage” of the working fluid past the vane, which reduces the performance of the turbomachinery device. In addition, rotation of the vane may result in increased gap widths, depending upon the angle of rotation of the vane and the surface geometry of the adjacent structures, which may increase the undesirable leakage of the working fluid. Since turbomachinery efficiency and the precision of turbomachinery control decrease with increasing vane end wall leakage, it is desirable to minimize or eliminate end wall leakage. 
     Referring now to  FIG. 1 , there is illustrated a generic representation of a turbomachinery device  10 . This non-limiting depiction of turbomachinery device  10  may include various components, including a gas turbine engine  11 , which may itself include a compressor section  12 , a combustor section  14  and a turbine section  16 . Turbomachinery device  10  may also include a lift fan  17  and a vanebox  18 . Each of gas turbine engine  11 , compressor section  12 , combustor section  14 , turbine section  16 , lift fan  17  and vanebox  18  are considered turbomachinery devices, individually and in combination, any or all of which may employ one or more vane assemblies and vane end seals in accordance with embodiments of the present invention, non-limiting examples of which are described herein. It will be noted that other turbomachinery devices, e.g., steam turbines and pumps, may also employ one or more vane assemblies and vane end seals in accordance with embodiments of the present invention. 
     Compressor section  12  includes one or more compressor stages (not shown), and in some embodiments may include one or more fan stages. Turbine section  16  includes one or more turbine stages (not shown). Turbine section  16  may be coupled to compressor section  12  via one or more shafts (not shown), and may provide power to compressor section  12 . Turbine section  16  may also be arranged to provide power for other components (not shown). In the present embodiment, power may be supplied from gas turbine engine  11  to lift fan  17  via a shaft system  19 . Lift fan  17  discharges air to provide thrust, e.g., for a short take-off vertical landing (STOVL) aircraft, which is passed through vanebox  18 . Vanebox  18  includes a plurality of airfoils in the form of rotatable vanes that may be rotated in a controlled manner by a mechanism (not shown) in order to control the amount and/or direction of thrust output by lift fan  17  in response to the aircraft pilot&#39;s control input. 
     Although the present invention is described herein with respect to rotatable vanes of vanebox  18 , it will be understood that the present invention is equally applicable to rotating vanes in other turbomachinery components, such as fans employed in turbofan engines, as well as lift fans, compressors, turbines, etc., and that the present invention is not limited to use in thrust control and/or vectoring devices, such as vanebox  18 . 
     Referring now to  FIG. 2 , a rotatable vane of vanebox  18 , identified herein as rotatable vane  20 , is depicted between two flow path defining structures, adjacent structures  30  and  40  (shown in cross section), that define therebetween a gas flow path  50 . Vane  20  includes end sections  24  and  26  that are adjacent to surfaces  31  and  41  of adjacent structures  30  and  40 , respectively. Each vane  20  may be configured to control the flow of the working fluid in turbomachinery device  10 , which in the present embodiment is the discharge air from lift fan  17 . The flow direction of the working fluid through flow path  50  is indicated by a direction arrow  52 . Structures  30  and  40  may be, for example and without limitation, walls, shrouds, stators, rotors or the like, all of which are referred to generally herein as “surrounding structure” or “adjacent structure.” Vane  20  is pivotable about an axis  22  that may extend approximately in the span-wise direction of vane  20 . In the present embodiment, this rotatability allows vanes  20  to control the flow path area of flow path  50 , and to control thrust output and direction. In one form, vane  20  is supported by adjacent structure  40  via a supporting member  42 , and is supported by adjacent structure  30  via a supporting member  32 . In other embodiments, other means of supporting vane  20  may be employed. 
     It is desirable that each vane  20  be free to rotate about axis  22  in a controlled manner (control mechanism not shown) and without binding, and hence, end sections  24  and  26  of each vane are  20  configured to be spaced apart from oppositely adjacent surfaces  31  and  41 , respectively, a sufficient distance to prevent contact between end sections  24 ,  26  and adjacent surfaces  31  and  41  during rotation of vane  20 , i.e., as vane  20  pivots about axis  22  and end sections  24  and  26  accordingly move in relation to adjacent surfaces  31  and  41  of adjacent structures  30  and  40 . The distance is depicted as gaps  34  and  44  between end sections  24  and  26  and adjacent surfaces  31  and  41 , respectively. 
     It is preferable to minimize end wall leakage of working fluid, as discussed above, and thus it is desirable to prevent or reduce flow through gaps  34  and  44  between vane end sections  24  and  26  and structures  30  and  40 . However, decreasing the widths of the gaps  34  and  44  may be problematic for various reasons, such as thermal expansion, build tolerances, deflections of vanebox  18  components occurring due to internally and external imposed loads, e.g., pressure differentials and aircraft maneuvering loads, respectively, which may dictate a minimum non-zero gap width between vane end sections  24 ,  26  and structures  30 ,  40 . In addition, the axis  22  of rotation of rotatable vane  20  may not be perfectly perpendicular to surfaces  31  and  41 , and the geometry of surfaces  31  and  41  may vary, thereby causing variations in the gap width as vane  20  is rotated. Thus, minimizing the gap in one position might leave a significantly larger gap when vane  20  is rotated to a different position, or might cause an end of vane  20  to contact an adjacent structure and prevent further movement the vane. Also, the surfaces of adjacent structures may not be planar or uniform, resulting in a similar problem. 
     The sealing of gaps  34  and  44  to reduce or prevent leakage between end sections  24  and  26  of vane  20  and walls  30  and  40 , respectively, may be accomplished by virtue of vane end seals in accordance with embodiments of the present invention, described herein. Because the manner of vane end sealing is accomplished according to the same general principles at both end sections  24  and  26  of vane  20 , attention will be directed with particular reference to the sealing of vane end section  24  that is proximate to flow path defining wall  30 . It will be understood that similar seals may be utilized in connection with opposite vane end section  26 , with other vane ends of vanes having differing dimensions and features, and that more than one such inventive seal assembly may be employed for each vane end section without departing from the scope of the present invention. 
     Referring now to  FIG. 3 , a vane end seal assembly  54  is depicted along with vane  20 . Seal assembly  54  includes a seal  56  and a biasing member  58  configured to urge sealing portion  62  in a direction toward surface  31 . Biasing member  58  has a first end  58 A and a second end  58 B. Seal  56  is configured to seal gap  34  between vane end section  24  and surface  31  of adjacent structure  30 . Seal  56  includes a body  60  with a sealing portion  62 . Sealing portion  62  is configured to seal against the surface of the adjacent structure, e.g., surface  31 . In one form, sealing portion  62  is an extension of body  60  and shares the same profile therewith. Alternatively, it is contemplated that sealing portion  62  may have a larger or smaller “footprint” than body  60 , e.g., have greater or lesser dimensions than body  60  as measured in a plane approximately perpendicular to axis  22 . Vane end section  24  includes a seal guide feature  25 . In one form, seal guide feature  25  is a cavity in vane end section  24  that faces surface  31 . In other embodiments, seal guide feature  25  may take other forms. 
     Seal guide feature  25  is configured to position seal  56  at a desired location in vane  20  in a plane approximately perpendicular to axis  22 . Seal guide feature  25  is also configured as a piloting feature to pilot body  60 , i.e., to guide seal  56  during translation of seal  56  in and out of vane end section  24 , e.g., in a direction  64 , such as might occur during the installation and removal of seal  56 , and/or as might occur due to contact with surface  31  of adjacent structure  30  during the rotation of vane  20 . In the present embodiment, direction  64  is parallel to axis  22 , although the present invention is not so limited. 
     In one form, seal guide feature  25  includes a piloting feature  66  that is configured to pilot one end of biasing member  58 , e.g., end  58 A. In the present embodiment, piloting feature  66  takes the form of a counterbore extending from seal guide feature  25  into vane  20 . In other embodiments, piloting feature  66  may take other forms. Still other embodiments may not include a piloting feature such as piloting feature  66  as part of the seal guide feature. In one form, seal body  60  also includes a piloting feature  68  configured to receive and pilot another end of biasing member  58 , e.g., end  58 B. In the present embodiment, piloting feature  68  is in the form of a counterbore extending into body  60 , although other forms may be employed in other embodiments. Still other embodiments may not include a piloting feature such as piloting feature  68  as part of the body. 
     The profile of body  60  may be contoured to match the profile of seal guide feature  25 , and is slidably received by seal guide feature  25 . The profile of sealing portion  62  may be contoured to match the profile of vane  20  at the location of end section  24 . 
     As represented herein, biasing member  58  may be in the form of a compression spring. However, a person of ordinary skill in the art will appreciate that alternative types of biasing members may be employed in other embodiments. For example, a torsional coil spring, a cantilever beam spring, a leaf spring and/or other suitable biasing devices may be employed in other embodiments of the present invention. 
     Biasing member  58  is received by seal guide feature  25 , and once vane  20  is installed into vanebox  18 , biases sealing portion  62  of seal body  60  against surface  31 , to thereby seal gap  34  (illustrated in  FIG. 2 ). In one form, body  60  and sealing portion  62  are formed of a low friction polymer, e.g., may be made from a low friction polymer. In other embodiments, body  60  and sealing portion  62  may include a low friction polymer surface treatment, in order to reduce wear and reduce the load on the mechanism that rotates vane  20 . In still other embodiments, a low friction material may not be employed on body  60  and/or sealing portion  62 . Examples of commercially available polymers suitable for the relatively low temperatures that may be encountered in vanebox  18 , lift fan  17  and a fan and low pressure compressor stages of compressor section  12 , may include VESPEL® and TEFLON® by DUPONT™, and TORLON® by Solvay Advanced Polymers. 
     Referring now to  FIG. 4 , vane  20  is depicted with seal assembly  54  installed. Gap  34  is not depicted in  FIG. 4  because its width has been filled by seal  56 . It is noted that, for purposes of illustration,  FIG. 4  does not depict a vane end seal for end section  26 , and hence, gap  44  is present. However, it will be understood, as set forth above, that a vane end seal for vane end section  26  may be similarly be provided in accordance with the description of vane end seal assembly  54 . 
     During the operation of vanebox  18 , biasing member  58  urges sealing portion  62  against surface  31  of adjacent structure  30 , which may seal the gap and thereby reduce leakage between vane end section  24  and adjacent structure  30 . In addition, in the event wear occurs due to the rotation of vane  20 , e.g., abrasive wear of sealing portion  62  due to moving contact with surface  31 , biasing member  58  continues to urge seal  56  in the direction of surface  31  (the direction may be governed by seal guide feature  25 ) thereby compensating for the material worn off of sealing portion  62 . 
     Referring now to  FIGS. 5 and 6 , a modification of the embodiment of  FIGS. 3 and 4  is depicted. In the embodiment depicted in  FIGS. 5 and 6 , seal body  60  may include one or more of a retention feature  70  that operates to prevent body  60  of seal  56  from completely exiting seal guide feature  25  until disengagement is desired, e.g., releasably retaining body  60  with seal guide feature  25 . The depiction of  FIGS. 5 and 6  includes two retention features  70 , although a greater or lesser number of retention features may be employed in other embodiments. Still other embodiments may not include any such retention feature. 
     In one form, retention feature  70  includes a cantilevered arm  72 . Cantilevered arm  72  includes a catch feature  74  at an end  76 , and is attached to body  60  at an end  78 . In one form, retention feature  70  is formed as part of body  60 , although in other embodiments, retention feature  70  may be formed separately from body  60  and attached thereto. In one form embodiment, cantilevered arm  72  is made from an elastic material that allows cantilevered arm  72  to deflect during the installation of seal  56  into vane  20 , and to snap back to a substantially undeflected position. 
     In one form, seal guide feature  25  includes a recess  80  and ramp  82  for each retention feature  70 . Recess  80  is configured to receive catch feature  74 , and catch feature  74  is configured for movement in recess  80 , e.g., in direction  64 . Recess  80  defines a clamping shoulder  84  that is positioned to engage catch feature  74  to thereby limit the extent of outward movement of body  60  from seal guide feature  25  beyond a predetermined limit. 
     Retention feature  70  may allow substantially unimpeded bidirectional movement of seal body  60  in direction  64  over a predetermined distance that may be selected as providing a range of motion for seal body  60  sufficient to allow sealing portion  62  to remain in contact with surface  31  of structure  30  by action of biasing member  58  as the width of gap  34  changes during normal rotation of vane  20 . In addition, the predetermined distance may also be selected to allow body  60  to extend from vane end  24  to compensate for wear at the surface of sealing portion  62  and/or surface  31  of adjacent structure  30 . Retention feature  70  thus provides a mechanism whereby seal body  60  may be removably attached to vane  20  during the assembly of vanebox  18  by directing body  60  into the cavity defining seal guide feature  25  until catch feature  74  clears clamping shoulder  84 . 
     During the installation of seal  56  into vane  20 , seal  56  is engaged with seal guide feature  25 , e.g., in the present embodiment, by directing seal body  60  (end  76  of each cantilevered arm  72  first) into the cavity defining seal guide feature  25 . During the insertion of seal  56  into vane end section  24 , ramp  82  may aid installation by smoothly “ramping up” the deflection of end  76  of cantilevered arm  72  in order clear shoulder  84 . Once catch feature  74  has cleared clamping shoulder  84 , cantilevered arm  72  returns substantially to it&#39;s original, undeflected position (e.g., minus a small amount of hysteresis), thereby creating an interference between catch feature  74  and clamping shoulder  84 , which retains catch feature  74  in recess  80 , thereby retaining seal  56  in vane end section  24 . Retention feature  70  holds seal  56  in place after vane  20  is removed from structures  30  and  40 , for example, during disassembly of vanebox  18  for repairs or for other reason. 
     Although a particular embodiment of retention feature  70  has been described herein, one skilled in the art would appreciate that retention feature  70  may take other forms in other embodiments. For example, retention feature  70  may be one of many latch configurations that take a positive locking approach or a passive locking approach. A positive latching approach may require that some portion of the device be manually pressed to disengage seal body  60  from seal guide feature  25 , whereas a passive latching approach may allow disengagement of seal body  60  from seal guide feature  25  by simply exerting a sufficient separating force upon the seal  60  to disengage the latch. 
     In one form, retention feature  70  employs a positive latching design, and may be removed by directing a tool, such as a rod (not shown), between body  60  and seal guide feature  25  at the location of ramp  82 , and forcing the rod in the direction of catch feature  74 . As the rod is moved toward catch feature  74 , it may employ ramp  82  as a lever device to deflect cantilevered arm  72  until catch feature  74  has cleared shoulder  84 , at which point seal  56  may be removed from vane end section  24 . 
     It should be apparent to one skilled in the art that certain changes can be made to the above-described invention without departing from the broad, inventive concepts thereof. For example, the seals of the present invention in alternative embodiments can be configured to be used in connection with compressor vanes, fan vanes, and/or turbine nozzle vanes of gas turbine engines, steam turbine vanes, pump vanes, or in connection with any other variable area turbomachinery vane, or turbine. Furthermore, the profile of the seal and its receiving cavity may be altered while still retaining the novel aspects of the invention. Vane  20  may also optionally include a wide variety of additional features not shown herein. For example, a plurality of internal passages may be provided that extend through the interior of vane  20 , ending in openings (not shown) in the trailing edge  28  of vane  20 . A flow of cooling air may be directed through the internal passages, to remove heat from vane  20  and/or seal  56 , if desired. In the present embodiment, vane  20  is made of a titanium alloy, although other materials may be used in other embodiments. 
     In addition, the present invention contemplates embodiments in which a vane end incorporates more than one seal guide feature, in which case the vane end seal may include a plurality of bodies and corresponding sealing portions. Also, different biasing members may be associated with each body/sealing surface, or a single biasing member may be employed. 
     The present invention also contemplates vane designs in which the vane portion extending beyond supporting members  32 ,  42  in the downstream direction (relative to the flow of working fluid) has a counterpart in the upstream direction. In such a design, vane end sections  24  and  26  may also have counterparts in the upstream direction forming additional gaps that can be sealed using seals provided in accordance with the present invention. As a skilled artisan will readily understand, some embodiments of the present invention may be employed advantageous use wherever a rotatable vane end and adjacent structures form a gap therebetween. 
     In one form, the present invention provides a rotatable vane assembly with a self-adjusting seal for sealing the gap between vane ends and the adjacent structure of the turbomachinery device. In one form, the assembly includes a vane configured to control the flow a working fluid in a turbomachinery device. In one form, one or more end sections of the vane, i.e., at the tip and/or root of the vane, include a seal guide feature that guides and pilots the seal. The seal may have a body that is slidably received by the guide feature, and may also have a sealing portion that seals against the surface of adjacent structures of the turbomachinery device into which the rotatable vane is installed. The seal body may be extendable from the vane&#39;s end section toward the surface of the adjacent structure in order to accommodate wear, and to seal between the vane end section and the surface despite possible changes in the gap width due to variations in the geometry of the surface of the adjacent structure, build tolerances, operational deflections, and thermal expansion. A biasing member, such as a compression spring, may bias the seal toward the surface of the adjacent structure. 
     Although embodiments described herein employ a seal guide feature in the form of a cavity that receives therein part of the body of the seal, it will be appreciated by those skilled in the art that other configurations may be employed without departing from the scope of the present invention. For example, one or more posts may be provided at the end sections of the vane, and a seal body may be slidably received over the one or more posts to thereby guide the seal body. 
     Embodiments of the present invention include a vane assembly for a turbomachinery device, the vane assembly comprising: a rotatable vane configured to control a flow of a working fluid in the turbomachinery device, the rotatable vane having at least one end section configured to be spaced apart from a surface of an adjacent structure of the turbomachinery device opposite the at least one end section to thereby leave a gap between the at least one end section and the surface, the at least one end section including a seal guide feature; a seal configured to seal the gap between the at least one end section and the surface, the seal including a body having a sealing portion, the body being configured to be slidably received by the seal guide feature at the at least one end section, and the sealing portion being configured to seal against the surface of the adjacent structure; and a biasing member configured to urge the sealing portion in a direction toward the surface. 
     In a refinement, the vane assembly further comprises a retention feature configured to releasably retain the body with the seal guide feature. 
     In another refinement, the seal guide feature includes a cavity in the at least one end section, wherein: the retention feature includes a cantilever latch arm having a first end, a second end opposite the first end, and a catch feature, the first end being attached to the body, and the catch feature being positioned on the second end; and the seal guide feature further includes a recess configured to receive the catch feature. 
     In yet another refinement, the catch feature is configured for movement within the recess; and the recess defines a shoulder positioned to engage the catch feature to thereby limit the extent of outward movement of the body from the cavity beyond a predetermined limit. 
     In still another refinement, the biasing member is a compression spring. 
     In yet still another refinement, the body includes a first pilot feature configured to pilot a first end of the spring, and wherein the seal guide feature includes a second pilot feature configured to pilot a second end of the spring. 
     In a further refinement, the seal guide feature includes a cavity in the at least one end section; wherein the cavity has an opening that faces the surface; and wherein the cavity defines a pilot feature for piloting the body. 
     In a yet further refinement, the sealing portion employs a low friction polymer. 
     Embodiments of the present invention include a vane assembly for a turbomachinery device, the assembly comprising: a rotatable vane configured to control a flow of a working fluid in the turbomachinery device, the rotatable vane having at least one end section configured to be spaced apart from a surface of an adjacent structure of the turbomachinery device that is opposite the at least one end section to thereby leave a gap between the at least one end section and the surface; means for sealing the gap between the at least one end section and the surface; and means for biasing the means for sealing toward the surface. 
     In a refinement, the means for sealing employs a low friction polymer. 
     In another refinement, the at least one end section defines a cavity configured to receive at least a part of the means for sealing; wherein the means for sealing includes both a body configured to reside in the cavity and means for contacting the surface; and wherein the cavity is configured to receive the body. 
     In yet another refinement, the means for sealing further includes means for retaining at least a part of the means for sealing in the cavity; wherein the cavity includes means for cooperating with the means for retaining to retain the means for sealing. 
     In still another refinement, the means for retaining includes a cantilever latch arm having a catch feature; wherein the means for cooperating includes a recess configured to receive and retain the catch feature. 
     In yet still another refinement, the catch feature is configured for movement within the recess; wherein the recess defines a shoulder positioned to engage the catch feature to thereby limit the extent of outward movement of the means for sealing from the cavity beyond a predetermined limit. 
     In a further refinement, the means for biasing is a compression spring; wherein the body defines a first pilot hole configured to pilot a first end of the spring. 
     In a yet further refinement, a second pilot hole configured to pilot a second end of the spring is formed in the cavity. 
     In a yet still further refinement, the means for biasing is a compression spring. 
     Embodiments of the present invention include a seal assembly for a rotatable vane of a turbomachinery device, comprising: a seal body configured to be movably received in a cavity formed in an end section of the rotatable vane, wherein the seal body includes a sealing portion configured to seal against a surface of a structure of the turbomachinery device that is adjacent to the rotatable vane, and the seal body being configured to span a variable gap between the end section and the surface of the adjacent structure. 
     In a refinement, the seal assembly further comprises a biasing member configured to urge the seal body in a direction toward the surface of the adjacent structure. 
     In another refinement, the biasing member is a compression spring. 
     In yet another refinement, the seal body defines a pilot feature for piloting an end of the spring. 
     In still another refinement, the seal assembly further comprises a retention feature configured to retain at least a part of the seal body in the cavity. 
     In yet still another refinement, the retention feature includes a cantilever latch arm having a first end, a second end opposite the first end, and a catch feature, wherein the first end is attached to the body; wherein the catch feature is positioned on the second end; and wherein the cavity includes a recess configured to receive the catch feature. 
     In a further refinement, the catch feature is configured for movement within the recess; and the recess defines a shoulder positioned to engage the catch feature to thereby limit the extent of outward movement of the body from the cavity beyond a predetermined limit. 
     In a yet further refinement, the sealing portion employs a low friction polymer. 
     Embodiments of the present invention include a turbomachinery device, comprising: a vane assembly, the vane assembly including: a rotatable vane configured to control a flow of a working fluid in the turbomachinery device, the rotatable vane having at least one end section configured to be spaced apart from a surface of an adjacent structure of the turbomachinery device opposite the at least one end section to thereby leave a gap between the at least one end section and the surface, the at least one end section including a seal guide feature; a seal configured to seal the gap between the at least one end section and the surface, the seal including a body having a sealing portion, the body being configured to be slidably received by the seal guide feature at the at least one end section, and the sealing portion being configured to seal against the surface of the adjacent structure; and a biasing member configured to urge the sealing portion in a direction toward the surface. 
     While the invention 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 invention is not to be limited to the disclosed embodiments, 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 invention, 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.