Abstract:
One embodiment of the present disclosure is a unique active seal system. Another embodiment is another unique active seal system. Another embodiment is a unique method for operating a turbomachine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for active seal 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. 61/777,993, filed 12 Mar. 2013, the disclosure of which is now expressly incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to gas turbine engines, and more particularly, to an active seal system for a gas turbine engine. 
       BACKGROUND 
       [0003]    Gas turbine engine seal systems that effectively respond to changes in engine operating points 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 active seal system. Another embodiment is another unique active seal system. Another embodiment is a unique method for operating a turbomachine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for active seal 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 illustrates 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  schematically illustrates some aspects of a non-limiting example of an active seal 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 , there are illustrated some aspects of a non-limiting example of a gas turbine engine  20  in accordance with an embodiment of the present disclosure. In one form, engine  20  is a propulsion engine, e.g., an aircraft propulsion engine. In other embodiments, engine  20  may be any other type of gas turbine engine, e.g., a marine gas turbine engine, an industrial gas turbine engine, or any aero, aero-derivative or non-aero gas turbine engine. In one form, engine  20  is a two spool engine having a high pressure (HP) spool  24  and a low pressure (LP) spool  26 . In other embodiments, engine  20  may include only a single spool, or may include three or more spools, e.g., may include an intermediate pressure (IP) spool and/or other spools and/or partial spools, e.g., on-axis or off-axis compressor and/or turbine stages (i.e., stages that rotate about an axis that is the same or different than that of the primary spool(s)). In one form, engine  20  is a turbofan engine. In other embodiments, engine  20  may be any other type of gas turbine engine, such as a turboprop engine, a turboshaft engine, a propfan engine, a turbojet engine or a hybrid or combined cycle engine. As a turbofan engine, LP spool  26  is operative to drive a propulsor  28  in the form of a turbofan (fan) system, which may be referred to as a turbofan, a fan or a fan system. As a turboprop engine, LP spool  26  powers a propulsor  28  in the form of a propeller system (not shown), e.g., via a reduction gearbox (not shown). As a propfan engine, LP spool  26  powers a propulsor  28  in the form of a propfan. In other embodiments, propulsor  28  may take other forms, such as one or more helicopter rotors or tilt-wing aircraft rotors, for example, powered by one or more engines  20  in the form of one or more turboshaft engines. 
         [0010]    In one form, engine  20  includes, in addition to fan  28 , a bypass duct  30 , a compressor  32 , a diffuser  34 , a combustor  36 , a high pressure (HP) turbine  38 , a low pressure (LP) turbine  40 , a nozzle  42 A, a nozzle  42 B, and a tailcone  46 , which are generally disposed about and/or rotate about an engine centerline  49 . In other embodiments, there may be, for example, an intermediate pressure spool having an intermediate pressure turbine or other turbomachinery components, such as those mentioned above. In one form, engine centerline  49  is the axis of rotation of fan  28 , compressor  32 , turbine  38  and turbine  40 . In other embodiments, one or more of fan  28 , compressor  32 , turbine  38  and turbine  40  may rotate about a different axis of rotation. 
         [0011]    In the depicted embodiment, engine  20  core flow is discharged through nozzle  42 A, and the bypass flow from fan  28  is discharged through nozzle  42 B. In other embodiments, other nozzle arrangements may be employed, e.g., a common nozzle for core and bypass flow; a nozzle for core flow, but no nozzle for bypass flow; or another nozzle arrangement. Bypass duct  30  and compressor  32  are in fluid communication with fan  28 . Nozzle  42 B is in fluid communication with bypass duct  30 . Diffuser  34  is in fluid communication with compressor  32 . Combustor  36  is fluidly disposed between compressor  32  and turbine  38 . Turbine  40  is fluidly disposed between turbine  38  and nozzle  42 A. In one form, combustor  36  includes a combustion liner (not shown) that contains a continuous combustion process. In other embodiments, combustor  36  may take other forms, and may be, for example, a wave rotor combustion system, a rotary valve combustion system, a pulse detonation combustion system, a continuous detonation combustion system and/or a slinger combustion system, and may employ deflagration and/or detonation combustion processes. 
         [0012]    Fan system  28  includes a fan rotor system  48  driven by LP spool  26 . In various embodiments, fan rotor system  48  may include one or more rotors (not shown) that are powered by turbine  40 . In various embodiments, fan  28  may include one or more fan vane stages (not shown in  FIG. 1 ) that cooperate with fan blades (not shown) of fan rotor system  48  to compress air and to generate a thrust-producing flow. Bypass duct  30  is operative to transmit a bypass flow generated by fan  28  around the core of engine  20 . Compressor  32  includes a compressor rotor system  50 . In various embodiments, compressor rotor system  50  includes one or more rotors (not shown) that are powered by turbine  38 . Compressor  32  also includes a plurality of compressor vane stages (not shown in  FIG. 1 ) that cooperate with compressor blades (not shown) of compressor rotor system  50  to compress air. In various embodiments, the compressor vane stages may include a compressor discharge vane stage and/or one or more diffuser vane stages. In one form, the compressor vane stages are stationary. In other embodiments, one or more vane stages may be replaced with one or more counter-rotating blade stages. 
         [0013]    Turbine  38  includes a turbine rotor system  52 . In various embodiments, turbine rotor system  52  includes one or more rotors having turbine blades (not shown) operative to extract power from the hot gases flowing through turbine  38  (not shown), to drive compressor rotor system  50 . Turbine  38  also includes a plurality of turbine vane stages (not shown) that cooperate with the turbine blades of turbine rotor system  52  to extract power from the hot gases discharged by combustor  36 . In one form, the turbine vane stages are stationary. In other embodiments, one or more vane stages may be replaced with one or more counter-rotating blade stages. Turbine rotor system  52  is drivingly coupled to compressor rotor system  50  via a shafting system  54 . Turbine  40  includes a turbine rotor system  56 . In various embodiments, turbine rotor system  56  includes one or more rotors having turbine blades (not shown) operative to drive fan rotor system  48 . Turbine  40  also includes a plurality of turbine vane stages (not shown in  FIG. 1 ) that cooperate with the turbine blades of turbine rotor system  56  to extract power from the hot gases discharged by turbine  38 . In one form, the turbine vane stages are stationary. In other embodiments, one or more vane stages may be replaced with one or more counter-rotating blade stages. Turbine rotor system  56  is drivingly coupled to fan rotor system  48  via a shafting system  58 . In various embodiments, shafting systems  54  and  58  include a plurality of shafts that may rotate at the same or different speeds and directions for driving fan rotor system  48  rotor(s) and compressor rotor system  50  rotor(s). In some embodiments, only a single shaft may be employed in one or both of shafting systems  54  and  58 . Turbine  40  is operative to discharge the engine  20  core flow to nozzle  42 A. 
         [0014]    During normal operation of gas turbine engine  20 , air is drawn into the inlet of fan  28  and pressurized. Some of the air pressurized by fan  28  is directed into compressor  32  as core flow, and some of the pressurized air is directed into bypass duct  30  as bypass flow. Compressor  32  further pressurizes the portion of the air received therein from fan  28 , which is then discharged into diffuser  34 . Diffuser  34  reduces the velocity of the pressurized air, and directs the diffused core airflow into combustor  36 . Fuel is mixed with the pressurized air in combustor  36 , which is then combusted. The hot gases exiting combustor  36  are directed into turbines  38  and  40 , which extract energy in the form of mechanical shaft power to drive compressor  32  and fan  28  via respective shafting systems  54  and  58 . The hot gases exiting turbine  40  are discharged through nozzle system  42 A, and provide a component of the thrust output by engine  20 . 
         [0015]    Engine  20  employs a plurality of seal systems for sealing fluids such as air and/or flowpath gases that include combustion products. For example and without limitation, some seal systems may be employed as fore, aft or interstage seals for fan  28 , compressor  32 , HP turbine  38  and/or LP turbine  40 . Seal systems may also be employed as thrust piston or thrust balance seals, which seal the gases used to balance engine rotor thrust. Seal systems may also be employed to control or limit the flow of gases into or out of engine sumps (not shown). Other seal systems may be employed for other purposes not mentioned herein. Seal types may include labyrinth seals having one or more knives that seal against another surface, such as a honeycomb or an abradable material. Other seal types may include brush seals. Yet other types of seals may include carbon or other contact seals, e.g., circumferential carbon seals and/or face seals. Still other seal types not mentioned herein may be employed. Some seal systems may employ a rotating seal component operating in conjunction with a stationary or static seal component to form a seal and control fluid flow therebetween. Other seal systems may employ a rotating seal component and another rotating seal component or a counter-rotating seal component to form a seal therebetween. In any event, it is desirable to control the flow through the seal systems, for example, in order to minimize engine losses, e.g., as with respect to fore, aft or interstage seals, as well as to more accurately control one or more of various engine parameters, e.g., thrust balance or sump purging and/or sump scavenge system operability (e.g., the latter of which may be affected by the amount of fluid entry or exit from a sump purge cavity). 
         [0016]    Referring to  FIG. 2 , some aspects of a non-limiting example of a sealing system  70  in accordance with an embodiment of the present disclosure is schematically depicted. In one form, sealing system  70  is configured for use in engine  20 . In other embodiments, seal system  70  may be configured for use in any rotating machine or machine having rotating components. Seal system  70  includes a support  72 , an outer seal component  74 , an inner seal component  76 , a plurality of electrical generator elements  78 , a plurality of electrical generator elements  80  and an active fiber composition portion  82 , also referred to as a piezoelectric portion  82 . In some embodiments, only a single electrical generator element  78  and/or a single electrical generator element  80  may be employed. As with regard to active fiber composition portion  82  or piezoelectric portion  82 , the term, “composition,” refers to all or part of active fiber composition portion  82  or piezoelectric portion  82  being formed of a composition material, i.e., a material made from at least two constituent materials, wherein at least one of the two constituent materials exhibits piezoelectric properties. 
         [0017]    Seal support  72  is configured to support outer seal component  74 , piezoelectric portion  78  and electrical generator elements  78 . In one form, seal support  72  is affixed to an engine structure  84  such as a case structure, for example, via a cross-key arrangement employing cross keys  86 . In other embodiments, seal support  72  may be affixed, coupled or otherwise engaged with any engine  20  structure, rotating or stationary, using any convenient means. 
         [0018]    Outer seal component  74  is configured to cooperate with inner seal component  76  to control or restrict the flow of fluid, e.g., air or other gases, through seal system  70 , i.e., between outer seal component  74  and inner seal component  76 . In one form, outer seal component  74  is a circumferential seal ring, i.e., extending circumferentially at a substantially constant diameter. In other embodiments, outer seal component  74  may take other forms. In one form, outer seal component  74  is a honeycomb seal. In other embodiments, outer seal component  74  may be one or more of other types of seal components, including, for example and without limitation, an abradable material seal, a brush seal component or any other types of seal suitable for use in a gas turbine engine or other turbomachine. In one form, outer seal component  74  is stationary, i.e., is a static seal component. In other embodiments, outer seal component  74  may be rotating in the same direction as inner seal component  76  or may be counter-rotating as with respect to inner seal component  76 . 
         [0019]    Inner seal component  76  is configured to cooperate with outer seal component  74  to seal, control and/or restrict the flow of fluid, e.g., air or other gases, through seal system  70 , i.e., between outer seal component  74  and inner seal component  76 . In one form, inner seal component  76  is a circumferential seal ring, i.e., extending circumferentially at a substantially constant diameter. In other embodiments, inner seal component  76  may take other forms, and may represent, for example and without limitation, a turbine blade or blade tip; a compressor blade or blade tip or a fan blade or blade tip, or compressor or turbine knife seals. In one form, inner seal component  76  is a knife seal, otherwise known as a labyrinth seal. In other embodiments, inner seal component  76  may be one or more of other types of seal components, including, for example and without limitation, an abradable material seal, a brush seal component or any other types of seal suitable for use in a gas turbine engine or other turbomachine. In one form, inner seal component  76  is rotating, i.e., is a rotating seal component. In other embodiments, inner seal component  76  may be a stationary seal component, i.e., is a static seal component. As a rotating seal or rotating seal component, inner seal component  76  may be, in various embodiments, configured to rotate in the same direction as outer seal component  74  or may be counter-rotating as with respect to outer seal component  74 . Inner seal component  76  forms a part of a rotor  77  that supplies rotation to inner seal component  76 . In various embodiments, inner seal component  76  may be formed as a part of rotor  77 , may be coupled or affixed to rotor  77 , or may be otherwise secured to rotor  77 . Outer seal component  74  is disposed adjacent to rotor  77 , in particular, to inner seal component  76 . 
         [0020]    In one form, electrical generator elements  78  and  80  form an electrical generator. In a particular form electrical generator elements  78  and  80  form an inductive generator. Electrical generator elements  78  and  80  are configured to cooperate to generate electrical power in electrical generator element  78  when inner seal component  76  and rotor  77  are rotated. Electrical generator elements  78  and  80  are configured to increase the power supplied to piezoelectric portion  82  with increasing proximity, e.g., increasing proximity (increasing closeness) of electrical generator elements  80  to electrical generator elements  78  as inner seal component  76  increases in size, e.g., due to an increasing rate of rotation of rotor  77 . 
         [0021]    Electrical generator elements  78  are in electrical communication with piezoelectric portion  82 , and are operative to deliver generated electrical power to piezoelectric portion  82 , in particular, to piezoelectric fibers disposed within the active fiber composition that forms piezoelectric portion  82 . In one form, a plurality of electrical generator elements  78  are employed, e.g., spaced apart circumferentially about support  72  and/or piezoelectric portion  82 . In other embodiments, only a single electrical generator element  78  may be employed. In one form, electrical generator elements  78  are disposed within support  72 . In other embodiments, electrical generator elements  78  may be disposed on an internal diameter or outside diameter of support  72 , within or on piezoelectric portion  82 , or any other location suitable for interaction with electrical generator elements  80 . In one form, electrical generator elements  78  are electrical windings. In other embodiments, electrical generator elements  78  may be in the form of electrical coils or one or more other devices configured to interact with electrical generator elements  80  for the purpose of generating electrical power in electrical generator elements  78 . 
         [0022]    Electrical generator elements  80  are retained on rotor  77 . In one form, electrical generator elements  80  are riveted in place. In other embodiments, electrical generator elements  80  may be fastened to rotor  77  using any suitable means. In some embodiments, electrical generator elements  80  may be embedded within one or more portions of rotor  77 . In one form, a plurality of electrical generator elements  80  are employed, e.g., spaced apart circumferentially about rotor  77 . In other embodiments, only a single electrical generator element  80  may be employed. In one form, electrical generator elements  80  are disposed about the periphery of rotor  77 . In other embodiments, electrical generator elements  80  may be disposed in any convenient location having relative proximity to electrical generator elements  78  for the generation of electrical power. In one form, electrical generator elements  80  are magnets. In a particular form, electrical generator elements are formed of a ferromagnetic material. In other embodiments, electrical generator elements  80  may be formed of other materials. 
         [0023]    Active fiber composition portion  82 , or piezoelectric portion  82  is in mechanical communication with, e.g., mechanically coupled to outer seal component  74  in a manner configured for transmitting loads to outer seal component  74  for controlling its size, e.g., diameter. In one form, piezoelectric portion  82  is bonded to outer seal component  74 . In other embodiments, other means of securing piezoelectric portion  82  to outer seal component  74  may be employed. In some embodiments, outer seal component  74  may be formed in whole or in part from piezoelectric portion  82 . In one form, piezoelectric portion  82  is a continuous piezoelectric ring. In other embodiments, piezoelectric portion  82  may be formed as a segmented ring. In still other embodiments, piezoelectric portion  82  may take other forms. Piezoelectric portion  82  is configured to expand when supplied with electrical power from electrical generator elements  78 , thereby expanding outer seal component  74 , and changing the size of outer seal component  74  in response to the electrical power received from electrical generator elements  78 . In one form, piezoelectric portion  82  includes piezoelectric elements embedded within one or more materials. For example, the piezoelectric materials may be embedded in a ceramic material; a composite material, such as a ceramic matrix composite, an organic matrix composite, a metal matrix composite, a carbon-carbon composite, and/or a reinforced polymer; and/or may be embedded in other senses of the term and within other materials in addition to or in place of the aforementioned materials, for example, embedding by lamination between layers of a metallic material, such as a steel, nickel, magnesium, aluminum, titanium, tungsten and/or various common metals, superalloys and/or other metals. In some embodiments, piezoelectric portion  82  may be made solely from one or more piezoelectric materials. A piezoelectric material is a material that exhibits piezoelectric properties, e.g., changes in physical dimensions based on changes in applied voltage or electrical power. In one form, the piezoelectric elements are piezoelectric materials in the form of piezoelectric fibers. In other embodiments, the piezoelectric elements may take other forms. In a particular form, the piezoelectric fibers are ceramic piezoelectric fibers. Examples of materials for forming ceramic piezoelectric fibers that are suitable for use in various locations of a gas turbine engine or other rotating machines include, but are not limited to, lead zirconate titanate (PZT) (e.g., available from PI Ceramic GmbH, headquartered in Lederhose, Germany); Bismuth Titanate (e.g., available from Piezo Technologies of Indianapolis, Ind., USA); and BiFeO 3 —PbZrO 3 —PbTiO 3 , a ternary solid solution. The gas turbine engine locations in which the ceramic piezoelectric fibers may be employed depends upon the temperature capabilities of the ceramic piezoelectric fiber material, which varies with the material&#39;s composition. For example, bismuth titanate exhibits a maximum temperature operating capability of approximately 770° F., whereas lead zirconate titanate exhibits a maximum temperature operating capability of approximately 300° F. Thus, bismuth titanate would be suitable for use in higher temperature locations of a gas turbine engine than those locations which would be appropriate for lead zirconate titanate usage. In other embodiments, other materials may be used to form the ceramic piezoelectric fibers. 
         [0024]    In one form, the size change of piezoelectric portion  82  and outer seal component  74  varies with the amount of electrical power received by piezoelectric portion  82  from electrical generator elements  78 . The amount of electrical power generated by electrical generator elements  78  and  80 , and supplied to piezoelectric portion  82  via electrical generator elements  78 , varies with the proximity of electrical generator elements  80  with respect to electrical generator elements  78 , and hence, increases with increasing proximity of electrical generator elements  80  to electrical generator elements  78 . Power output also varies with rotational speed, e.g., of inner seal component  76 /rotor  77 . Radial growth of rotor  77  and inner seal component  76 , e.g., due to an increased rate of rotation of rotor  77  and inner seal component  76  and the concomitant centrifugal forces acting thereon, and/or temperature changes in rotor  77  and inner seal component  76 , and/or pressure loading of rotor  77  and inner seal component  76 , increases the proximity of electrical generator elements  80  to electrical generator elements  78 , which increases the electrical charge delivered by electrical generator elements  78  to piezoelectric portion  82 , thereby increasing the size, e.g., diameter, of piezoelectric portion  82 , and hence the size/diameter of outer seal component  74 , thereby controlling the gap between outer seal component  74  and inner seal component  76  and achieving a desired gap between outer seal component  74  and inner seal component  76 . Similarly, a reduction in the rate of rotation of rotor  77  and inner seal component  76  reduces the proximity of electrical generator elements  80  with respect to electrical generator elements  78 , thereby reducing the amount of electrical power generated and delivered to piezoelectric portion  82 , thereby reducing the size, e.g., diameter of piezoelectric portion  82  and hence that of outer seal component  74 , achieving a desired gap between outer seal component  74  and inner seal component  76 . Accordingly, in one aspect of embodiments of the present disclosure, a seal gap or flow area may be controlled essentially automatically by the rate of rotation of the rotor, e.g., rotor  77 /inner seal component  76 . In some embodiments, electronic components, may be employed to smooth or otherwise condition the about of power supplied to piezoelectric portion  82 . In other embodiments, electronic components may be employed in order to control the power delivered to piezoelectric portion  82  in order to optimize the gap between outer seal component  74  and inner seal component  76  at one or more operating conditions, including transient and/or steady state conditions. 
         [0025]    During the operation of engine  20 , increases in the size, e.g., diameter, of inner seal component  76 , e.g., due to increases in rotational speed of rotor  77 , temperature increases and/or pressure increases in rotor  77  and/or inner seal component  76 , increase the proximity of electrical generator elements  80  as with respect to electrical generator elements  78 , resulting in increased power output from electrical generator elements  80  into piezoelectric portion  82 . The increased power increases the size, e.g., diameter, of piezoelectric portion  82 , and hence, outer seal component  74 , maintaining a desired gap between inner seal component  76  and outer seal component  74 . Conversely, decreases in the size, e.g., diameter, of inner seal component  76 , e.g., due to decreases in rotational speed of rotor  77 , temperature increases and/or pressure increases in rotor  77  and/or inner seal component  76 , decreases the proximity of electrical generator elements  80  as with respect to electrical generator elements  78 , resulting in decreased power output from electrical generator elements  80  into piezoelectric portion  82 . The decreased power decreases the size, e.g., diameter, of piezoelectric portion  82 , and hence, outer seal component  74 , maintaining a desired gap between inner seal component  76  and outer seal component  74 . 
         [0026]    Embodiments of the present disclosure include an active seal system, comprising: a rotor having a rotating seal component and a first electrical generator element; and a stationary seal component disposed adjacent to the rotor and having a second electrical generator element and a piezoelectric portion in electrical communication with the second electrical generator element, wherein the first electrical generator element and the second electrical generator element are configured to cooperate to generate electrical power in the second electrical generator element when the rotor is rotated; and wherein the piezoelectric portion is configured to change a size of at least a part of the stationary seal component in response electrical power received from the second electrical generator element. 
         [0027]    In a refinement, the first electrical generating element and the second electrical generating element form an electrical generator. 
         [0028]    In another refinement, the electrical generator is an inductive generator. 
         [0029]    In yet another refinement, the size change of the at least a part of the stationary seal component varies with an amount of the electrical power received by the piezoelectric portion. 
         [0030]    In still another refinement, the amount of the electrical power received by the piezoelectric portion increases with increasing proximity of the first electrical generator element to the second electrical generator element. 
         [0031]    In yet still another refinement, the active seal system is configured whereby radial growth of the rotor increases proximity of the first electrical generator element to the second electrical generator element. 
         [0032]    In a further refinement, the at least a part of the stationary seal component is a static seal; wherein the piezoelectric portion is in mechanical communication with the static seal; and wherein the static seal is configured to seal a fluid in conjunction with a rotating seal. 
         [0033]    In a yet further refinement, the rotating sealing component is a circumferential seal ring. 
         [0034]    In a still further refinement, the stationary seal component is a circumferential seal ring. 
         [0035]    In a yet still further refinement, the piezoelectric portion is formed of a composition material including an embedded piezoelectric material. 
         [0036]    In another further refinement, the piezoelectric portion is formed at least in part of ceramic piezoelectric fibers. 
         [0037]    In yet another further refinement, the piezoelectric portion is a component of a fluid seal operable to interface with another component of the active seal system to restrict or control the flow of a fluid through the active seal system. 
         [0038]    In still another further refinement, the first electrical generating element is disposed about the periphery of the rotor. 
         [0039]    Embodiments of the present disclosure include an active seal system, comprising: a first electrical generator element; a second electrical generator element; a piezoelectric structure in electrical communication with the second electrical generator element; and a static seal in mechanical communication with the piezoelectric structure, wherein the static seal is disposed about an axis, wherein the first electrical generator element and the second electrical generator element are configured to cooperate to generate electrical power in the second electrical generator element upon a rotation of the first electrical generator element about the axis; and wherein the piezoelectric portion is configured to change a size of the static seal in response electrical power received from the second electrical generator element. 
         [0040]    In a refinement, the size change of the static seal varies with an amount of the electrical power received by the piezoelectric structure. 
         [0041]    In another refinement, the amount of the electrical power received by the piezoelectric structure increases with increasing proximity of the first electrical generator element to the second electrical generating element. 
         [0042]    In yet another refinement, the active seal system further comprises a rotating seal, wherein the static seal is configured to seal a fluid in conjunction with a rotating seal. 
         [0043]    Embodiments of the present disclosure include a method for operating a turbomachine, comprising: rotating a first electrical generating element past a second electrical generating element to generate electrical power in the second electrical generating element; supplying the electrical power to a piezoelectric structure to change a size of the piezoelectric structure; and mechanically communicating the size change of the piezoelectric structure to a static seal structure to vary the size of the static seal. 
         [0044]    In a refinement, the method further comprises positioning the second electrical generating element adjacent to or within the piezoelectric structure. 
         [0045]    In another refinement, the method further comprises positioning the first electrical generating elements adjacent to or within a rotating seal disposed adjacent to the static seal. 
         [0046]    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.