BACKGROUND

[0001] An industrial gas turbine engine typically includes a compressor section, a turbine section, and a mid-frame section disposed therebetween. The compressor section includes multiple stages of rotating compressor blades and stationary compressor vanes and an outlet guide vane assembly aft of the last stage of rotating compressor blades and stationary compressor vanes. The mid-frame section typically includes a compressor exit diffusor and a combustor. The compressor exit diffusor diffuses the compressed air from the compressor section into a plenum through which the compressed air flows to a combustor which mixes the compressed air with fuel, ignites the mixture, and transits the ignited mixture to the turbine section to generate mechanical power. The turbine section includes multiple stages of rotating turbine blades and stationary turbine vanes.

[0002] Cooling air may be bled from the compressor section and directed to the turbine section to cool the hot components in the turbine section. Cooling air may leak through gaps between components in the gas turbine engine.

BRIEF SUMMARY

[0003] In one construction, a gas turbine engine includes a stationary component, a rotating component rotatable relative to the stationary component, and a non-contact seal assembly arranged between the stationary component and the rotating component configured to seal a gap therebetween. The non-contact seal assembly includes a plurality of seal segments circumferentially arranged adjacent to and spaced apart from each other. Each seal segment includes a seal carrier attached to the stationary component, a seal shoe movable with respect to the rotating component and the seal carrier, a coupling assembly separate from the seal carrier and the seal shoe, the coupling assembly coupled to the seal carrier and the seal shoe to allow movement of the seal shoe with respect to the rotating component and the seal carrier, a back plate removable connected to the seal carrier, and a front plate removable connected to the seal carrier such that the seal carrier is disposed between the back plate and the front plate.

[0004] In another construction, a gas turbine engine includes a stationary component, a rotating component rotatable relative to the stationary component, and a non-contact seal assembly arranged between the stationary component and the rotating component configured to seal a gap therebetween. The non-contact seal assembly includes a plurality of seal segments circumferentially arranged adjacent to and spaced apart from each other. Each seal segment includes a seal carrier attached to the stationary component, a seal shoe movable with respect to the rotating component and the seal carrier, a means for coupling the seal carrier and the seal shoe to allow movement of the seal shoe with respect to the rotating component and the seal carrier, a back plate removable connected to the seal carrier, and a front plate removable connected to the seal carrier such that the seal carrier is disposed between the back plate and the front plate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0006] FIG. 1 is a longitudinal cross-sectional view of a gas turbine engine taken along a plane that contains a longitudinal axis or central axis.

[0007] FIG. 2 illustrates a mid-frame section of the gas turbine engine.

[0008] FIG. 3 illustrates a non-contact seal assembly having a plurality of seal segments.

[0009] FIG. 4 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0010] FIG. 5 illustrates the front plate of the seal segment in accordance with FIG. 4.

[0011] FIG. 6 illustrates an exploded view of the seal carrier and seal shoe of the seal segment in accordance with FIG. 4. [0012] FIG. 7 illustrates a section view of the seal segment in accordance with FIG. 4.

[0013] FIG. 8 illustrates an assembled view of the seal segment in accordance with FIG. 4.

[0014] FIG. 9 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0015] FIG. 10 illustrates a section view of the seal segment in accordance with FIG. 9.

[0016] FIG. 11 illustrates an assembled view of the seal segment in accordance with FIG. 9.

[0017] FIG. 12 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0018] FIG. 13 illustrates an assembled view of the seal segment in accordance with FIG. 12.

[0019] FIG. 14 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0020] FIG. 15 illustrates an assembled view of the seal segment in accordance with FIG. 14.

[0021] FIG. 16 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0022] FIG. 17 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0023] FIG. 18 illustrates a front plate of the seal segment in accordance with FIG. 17.

[0024] FIG. 19 illustrates a section view of the seal segment in accordance with FIG. 17.

[0025] FIG. 20 illustrates an assembled view of the seal segment with the front plate removed in accordance with FIG. 17. [0026] FIG. 21 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0027] FIG. 22 illustrates a section view of the seal segment in accordance with FIG. 21.

[0028] FIG. 23 illustrates an assembled view of the seal segment in accordance with FIG. 21.

[0029] FIG. 24 illustrates an exploded view of a seal segment in accordance with one embodiment.

[0030] FIG. 25 illustrates a seal shoe of the seal segment in accordance with one embodiment FIG. 24.

[0031] FIG. 26 illustrates a section view of the seal segment in accordance with FIG. 24.

[0032] FIG. 27 illustrates an assembled view of the seal segment in accordance with FIG. 24.

DETAILED DESCRIPTION

[0033] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0034] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0035] Also, it should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and/or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0036] Also, although the terms "first", "second", "third" and so forth may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure. [0037] In addition, the term "adjacent to" may mean: that an element is relatively near to but not in contact with a further element; or that the element is in contact with the further portion, unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0038] For illustration purpose, term “axial” or “axially” refers to a direction along a longitudinal axis of a gas turbine engine, term “radial” or “radially” refers to a direction perpendicular to the longitudinal axis of the gas turbine engine, term “downstream” or “aft” refers to a direction along a flow direction, term “upstream” or “forward” refers to a direction against the flow direction.

[0039] FIG. 1 illustrates an example of a gas turbine engine 100 including a compressor section 102, a combustion section 104, and a turbine section 106 arranged along a central axis 108. The compressor section 102 includes a plurality of compressor stages 110 with each compressor stage 110 including a set of rotating compressor blades 114 and a set of stationary compressor vanes 112 or adjustable guide vanes. A rotor 116 supports the rotating compressor blades 114 for rotation about the central axis 108 during operation. In some constructions, a single one- piece rotor 116 extends the length of the gas turbine engine 100 and is supported for rotation by a bearing at either end. In other constructions, the rotor 116 is assembled from several separate spools that are attached to one another or may include multiple disk sections that are attached via a bolt or plurality of bolts.

[0040] The compressor section 102 is in fluid communication with an inlet section 118 to allow the gas turbine engine 100 to draw atmospheric air into the compressor section 102. During operation of the gas turbine engine 100, the compressor section 102 draws in atmospheric air and compresses that air for delivery to the combustion section 104. The illustrated compressor section 102 is an example of one compressor section 102 with other arrangements and designs being possible. [0041] In the illustrated construction, the combustion section 104 includes a plurality of separate combustors 120 that each operate to mix a flow of fuel with the compressed air from the compressor section 102 and to combust that air-fuel mixture to produce a flow of high temperature, high pressure combustion gas 122. Of course, many other arrangements of the combustion section 104 are possible.

[0042] The turbine section 106 includes a plurality of turbine stages 124 with each turbine stage 124 including a set of rotating turbine blades 130 and a set of stationary turbine vanes 132. The turbine stages 124 are arranged to receive the combustion gas 122 from the combustion section 104 at a turbine inlet 126 and expand that gas to convert thermal and pressure energy into rotating or mechanical work. The turbine section 106 is connected to the compressor section 102 to drive the compressor section 102. For gas turbine engine 100 used for power generation or as prime movers, the turbine section 106 is also connected to a generator, pump, or other device to be driven. As with the compressor section 102, other designs and arrangements of the turbine section 106 are possible.

[0043] A control system 128 is coupled to the gas turbine engine 100 and operates to monitor various operating parameters and to control various operations of the gas turbine engine 100. In preferred constructions the control system 128 is typically micro-processor based and includes memory devices and data storage devices for collecting, analyzing, and storing data. In addition, the control system 128 provides output data to various devices including monitors, printers, indicators, and the like that allow users to interface with the control system 128 to provide inputs or adjustments. In the example of a power generation system, a user may input a power output set point and the control system 128 may adjust the various control inputs to achieve that power output in an efficient manner.

[0044] The control system 128 can control various operating parameters including, but not limited to variable inlet guide vane positions, fuel flow rates and pressures, engine speed, valve positions, generator load, and generator excitation. Of course, other applications may have fewer or more controllable devices. The control system 128 also monitors various parameters to assure that the gas turbine engine 100 is operating properly. Some parameters that are monitored may include inlet air temperature, compressor outlet temperature and pressure, combustor outlet temperature, fuel flow rate, generator power output, bearing temperature, and the like. Many of these measurements are displayed for the user and are logged for later review should such a review be necessary.

[0045] FIG. 2 illustrates the mid-frame section 200 of the gas turbine engine 100. The mid-frame section 200 includes a compressor exit diffusor 204 and the combustion section 104. The compressed air 214 exits the compressor section 102 through an outlet guide vane 202 and enters the compressor exit diffusor 204. The compressor exit diffusor 204 includes an outer compressor exit diffusor 206 and an inner compressor exit diffusor 208 connected by a strut 210. The compressor exit diffusor 204 diffuses the compressed air 214 as it flows to the combustors 120. The compressed air 214 is mixed with fuel and the mixture is ignited in the combustors 120 to form the combustion gas 122. The combustion gas 122 is expanded in the turbine section 106 to convert thermal and pressure energy into rotating or mechanical work. The rotor 116 is at least partially or fully enclosed by a stationary shaft cover 212. Gaps 216 exist circumferentially between components, such as between the stationary shaft cover 212 and the rotor 116, or between the stationary inner compressor exit diffusor 208 and the rotor 116. Gaps 216 extend in a radial direction and circumferentially around and between the relatively movable components.

[0046] In many constructions, the rotating turbine blades 130 and stationary turbine vanes 132 need to be cooled using cooling air extracted from the compressor section 102. Cooling air can leak at gaps 216 between components which negatively affects performance and efficiency of the gas turbine engine 100. A non-contact seal assembly 300 is disposed between the gap 216 to reduce the cooling air leakage. [0047] As shown in FIG. 2, the non-contact seal assembly 300 is arranged at a stationary component, such as the stationary shaft cover 212 or the stationary inner compressor exit diffusor 208 to reduce the leakage between the shaft cover 212 or the inner compressor exit diffusor 208 and the rotor 116. It is understood that the non-contact seal assembly 300 may be arranged at a rotating component, such as the rotor 116. As shown in FIG. 2, one non-contact seal assembly 300 is disposed at a forward side of the stationary shaft cover 212 and one non-contact seal assembly 300 is disposed at an aft side of the stationary inner compressor exit diffusor 208. It is understood that the non-contact seal assembly 300 may be disposed at any locations of the gas turbine engine 100 where cooling air leakage may occur.

[0048] FIG. 3 illustrates a schematic view of a non-contact seal assembly 300. The non-contact seal assembly 300 includes a plurality of seal segments 400. The plurality of seal segments 400 are circumferentially arranged adjacent to each other to form a circular seal between the stationary component and the rotating component. Small intervals 302 exist between adjacent seal segments 400. The intervals 302 may be used to adapt thermal expansion and/or tolerance of manufacturing and assembly. The intervals 302 also allow the seal segments 400 to move radially inward so that a seal clearance can be adjusted. As shown in FIG. 3, the non-contact seal assembly 300 includes six 60-degree seal segments 400. It is understood that the non-contact seal assembly 300 may include any number of seal segments 400 to form a circular seal.

[0049] FIG. 4 illustrates an exploded view of a seal segment 400. The seal segment 400 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, and a plurality of fasteners 418. The back plate 408 is an integral one piece with the seal carrier 402. The back plate 408 is integrally positioned at the aft side of the seal carrier 402. The coupling assembly 406 couples the seal shoe 404 to the seal carrier 402. The fasteners 418 connect the forward secondary seal 414, the aft secondary seal 416, the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408 via apertures 444. The fasteners 418 connect the components from the back plate 408 to the front plate 412.

[0050] The seal carrier 402 is attached to the stationary component, such as the shaft cover 212 or the inner compressor exit diffusor 208. The seal carrier 402 has two arms 424 extending radially inward at two circumferential ends, respectively.

The two arms 424 define two recesses 426 between a central portion 428 and the two arms 424, respectively. The seal carrier 402 includes two first keyhole slots 430. Each first keyhole slot 430 is arranged in each arm 424. The first keyhole slot 430 includes a first round opening 432 at one end of a first rectangular slot 434. The central portion 428 includes a plurality of apertures 444. The apertures 444 pass through the back plate 408 to receive the fasteners 418.

[0051] The seal shoe 404 has two protrusions 436 extending radially upward at two circumferential ends, respectively. The seal shoe 404 includes two second keyhole slots 446. Each second keyhole slot 446 is arranged in each protrusion 436. The second keyhole slot 446 includes a second round opening 448 at one end of a second rectangular slot 450. The seal shoe 404 has a first plate 438 and a second plate 442 extending circumferentially between the two protrusions 436. The first plate 438 and second plate 442 define a pocket 452 extending circumferentially between the protrusions 436. The pocket 452 reduces a weight of the seal shoe 404. The dynamics of the circumferential hollow shaped seal shoe 404 may be optimized with reduced weight.

[0052] The coupling assembly 406 includes two seal springs 410. The two seal springs 410 are identical and are mirror imaged positioned at two circumferential ends of the seal segment 400. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 at the two circumferential ends of the seal segment 400. The seal spring 410 is a U-shaped leaf spring having a first leg 454 and a second leg 456. The first end of the seal spring 410 has a first cylindrical end 458 at an end of the first leg 454. The second end of the seal spring 410 has a second cylindrical end 460 at an end of the second leg 456.

[0053] The seal segment 400 includes a plurality of anti-rotation pins 440 for coupling the seal shoe 404 to the back plate 408. The back plate 408 includes a plurality of pin holes 420 for fixing the anti-rotation pins 440. The seal shoe 404 includes a plurality of elongated pin holes 602 (shown in FIG. 6) that are elongated in a radial direction. The elongated pin holes 602 fit the anti-rotation pins 440 to allow the seal shoe 404 to move in the radial direction with respect to the seal carrier 402 and to restrict the seal shoe 404 to move in a circumferential direction. It is understood that the back plate 408 may include the elongated pin holes 602 and the seal shoe 404 may include the pin holes 420. [0054] The seal segment 400 includes at least one secondary seal. As shown in FIG. 4, the at least one secondary seal includes a forward secondary seal 414 and an aft secondary seal 416. The forward secondary seal 414 and the aft secondary seal 416 are attached between the front plate 412 and the seal carrier 402 via the fasteners 418 passing the apertures 444. The forward secondary seal 414 and the aft secondary seal 416 may be made from different materials for providing different functions. For example, the forward secondary seal 414 may be stiff or thick for providing stiffness to reduce reverse cantilever deflection of the aft secondary seal 416. The aft secondary seal 416 may be less stiff or thin to enable contact from cantilever deflection. The aft secondary seal 416 has a thicker edge 462 disposed at the radial inner edge to provide sufficient wear life due to contact to the seal shoe 404.

[0055] The front plate 412 includes a plurality of apertures 444 to receive the fasteners 418. The front plate 412 includes at least one groove 422, which is described in FIG. 5.

[0056] FIG. 5 illustrates a view of the front plate 412 looking from the aft side of the seal segment 400. The front plate 412 has at least one groove 422. The groove 422 is disposed at the aft side surface 502 of the front plate 412. The groove 422 may extend in a direction perpendicularly to an outermost radial surface 504 and an innermost radial surface 506. The groove 422 may also extend in a direction at an angle with respect to the outermost radial surface 504 and the innermost radial surface 506. The groove 422 may extend from the outermost radial surface 504 to the innermost radial surface 506. The groove 422 reduces accumulation of debris at the forward secondary seal 414.

[0057] FIG. 6 illustrates an exploded view of the seal carrier 402 and the seal shoe 404. The elongated pin holes 602 are disposed from the aft side of the seal shoe 404. The elongated pin holes 602 extend radially at the protrusions 436, respectively. [0058] The seal shoe 404 includes an aft plate 604 circumferentially extending along the seal shoe 404. The aft plate 604 is disposed aft the second plate 442. A circumferential back pocket 606 is defined between the second plate 442 and the aft plate 604. The back plate 408 includes a dent 608 at the aft side for engaging the back pocket 606 of the seal shoe 404. The engagement restricts the seal shoe 404 from rotating about its longitudinal axis.

[0059] FIG. 7 illustrates a section view of the seal segment 400. The first leg 454 of the seal spring 410 is attached to the seal carrier 402 by sliding the first cylindrical end 458 into the first round opening 432 of the first keyhole slot 430. An end portion of the first leg 454 slides into the first rectangular slot 434. A diameter of the first cylindrical end 458 is larger than a diameter of the first round opening 432 for fixing the first leg 454 to the seal carrier 402 once assembled.

[0060] The second leg 456 of the seal spring 410 is attached to the seal shoe 404 by sliding the second cylindrical end 460 into the second round opening 448 of the second keyhole slot 446. An end portion of the second leg 456 slides into the second rectangular slot 450. A diameter of the second cylindrical end 460 is larger than a diameter of the second round opening 448 for fixing the second leg 456 to the seal shoe 404 once assembled.

[0061] Each recess 426 receives each seal spring 410 and allows a movement of the seal spring 410. The seal shoe 404 includes a plurality of the elongated pin holes 602 to receive the anti-rotation pins 440.

[0062] FIG. 8 illustrates an assembled view of the seal segment 400. The fasteners 418 connect the forward secondary seal 414, the aft secondary seal 416, the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402.

The back plate 408 is placed at the aft side of the seal carrier 402. The forward secondary seal 414 and the aft secondary seal 416 are placed between the front plate 412 and the seal shoe 404. A sliding interface exists between the aft secondary seal 416 and the seal shoe 404.

[0063] In operation of the gas turbine engine 100, aerodynamic loads are developed which apply a fluid pressure to the seal shoe 404 causing the seal shoe 404 to move radially inwardly and outwardly with respect to the rotating component, such as the rotor 116. The radial loads applied to the seal shoe 404 by the seal springs 410 are balanced between the two protrusions 436 at the two circumferential ends of the seal segment 400.

[0064] The seal springs 410 deflect and move radially inwardly and outwardly with the seal shoe 404 in the recesses 426. The radial movement of the seal shoe 404 with respect to the rotor 116 creates a primary seal for reducing cooling air leakage through the gap 216 between the stationary component and the rotating component within a predetermined design clearance.

[0065] The forward secondary seal 414 and the aft secondary seal 416 creates a secondary seal for reducing cooling air leakage between the seal carrier 402 and the seal shoe 404. The secondary seal separates the forward side high pressure zone from the aft side low pressure zone of the seal segment 400 to maintain a pressure gradient between the forward side pressure zone and the aft side pressure zone of the seal segment 400. The pressure gradient allows the seal shoe 404 to self-adjust its radial positioning for creating the primary seal in the gap 216 within the predetermined design clearance. The non-contact seal assembly 300 thus provides sufficient sealing between the rotating component and the stationary component.

[0066] FIG. 9 illustrates an exploded view of a seal segment 900. The seal segment 900 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, a plurality of fasteners 418. The back plate 408 is a separate piece from the seal carrier 402. The back plate 408 includes a plurality of venting holes 902 for balancing pressure difference from the forward side to the aft side of the seal segment 900.

[0067] The coupling assembly 406 includes two identical seal springs 410. The two seal springs 410 are mirror imaged positioned at two circumferential ends of the seal segment 900. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 at the two circumferential ends of the seal segment 900. Each seal spring 410 includes a first leg 454 and a second leg 456. Each seal spring 410 couples the seal shoe 404 to the seal carrier 402 by an engagement between the first leg 454 and the first keyhole slot 430 and an engagement between the second leg 456 and the second keyhole slot 446 similar as the seal segment 400. [0068] The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the back plate 408. The fasteners 418 connect the seal carrier 402 from the front plate 412 to the back plate 408.

[0069] The front plate 412 includes an indentation 904. The indentation 904 is disposed in the forward side of the front plate 412 and in a radially inward position. The configuration of the front plate 412 integrates functions of a secondary seal to the front plate 412, which replaces a separate secondary seal.

[0070] The seal segment 900 includes a plurality of anti-rotation pins 440 for coupling the seal shoe 404 to the back plate 408. The back plate 408 includes an elongated pin hole 602 that is elongated in a radial direction. The seal shoe 404 includes a pin hole 420 disposed at the key 1604 (not shown) for fixing the anti rotation pins 440. The elongated pin hole 602 fit the anti-rotation pin 440 allow the seal shoe 404 to move in the radial direction with respect to the seal carrier 402 and to restrict the seal shoe 404 to move in a circumferential direction. It is understood that the back plate 408 may include the pin hole 420 and the seal shoe 404 may include the elongated pin hole 602 disposed at the key 1604.

[0071] The front plate 412 includes an indentation 1402 The seal segment 1600 includes a seal strip 1404.

[0072] The configuration of the seal segment 900 is otherwise corresponds to the configuration of the seal segment 400. Corresponding components of the seal segment 900 are correspondingly labeled, which are not described in detail with respect to the seal segment 900.

[0073] FIG. 10 illustrates a section view of the assembled seal segment 900. The first leg 454 of the seal spring 410 is attached to the seal carrier 402 by sliding the first cylindrical end 458 into the first round opening 432 of the first keyhole slot 430. An end portion of the first leg 454 slides into the first rectangular slot 434. A diameter of the first cylindrical end 458 is larger than a diameter of the first round opening 432 for fixing the first leg 454 to the seal carrier 402 once assembled. [0074] The second leg 456 of the seal spring 410 is attached to the seal shoe 404 by sliding the second cylindrical end 460 into the second round opening 448 of the second keyhole slot 446. An end portion of the second leg 456 slides into the second rectangular slot 450. A diameter of the second cylindrical end 460 is larger than a diameter of the second round opening 448 for fixing the second leg 456 to the seal shoe 404 once assembled.

[0075] Each recess 426 receives each seal spring 410 and allows a movement of the seal spring 410. The seal shoe 404 includes a plurality of pin holes 420 to receive the anti-rotation pins 440.

[0076] FIG. 11 illustrates an assembled view of the 900. The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the seal carrier 402.

[0077] A sliding interface exists between the aft side of the front plate 412 and the seal shoe 404 which creates the secondary seal for reducing cooling air leakage between the seal carrier 402 and the seal shoe 404. A secondary seal is integrated with the front plate 412. A separated secondary seal is thus eliminated.

[0078] FIG. 12 illustrates an exploded view of a seal segment 1200. The seal segment 1200 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, and a plurality of fasteners 418. The back plate 408 is an integral one piece with the seal carrier 402. The back plate 408 is integrally positioned at the aft side of the seal carrier 402.

[0079] The coupling assembly 406 includes two identical seal springs 410. The two seal springs 410 are mirror imaged positioned at two circumferential ends of the seal segment 1200. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 via the first keyhole slots 430 in the seal shoe 404 and the second keyhole slots 446 in the seal shoe 404 at the two circumferential ends of the seal segment 1200.

[0080] The seal segment 1200 includes a plurality of anti-rotation pins 440 and a plurality of sleeves 1204. Each anti-rotation pin 440 is inserted in each sleeve 1204, respectively, for coupling the seal shoe 404 to the back plate 408. The back plate 408 includes a plurality of pin holes 420 for fixing the anti-rotation pins 440 with the sleeves 1204. The seal shoe 404 includes a plurality of elongated pin holes 602 that are elongated in a radial direction. The elongated pin holes 602 fit the anti-rotation pins 440 with the sleeves 1204 to allow the seal shoe 404 to move in the radial direction with respect to the seal carrier 402 and to restrict the seal shoe 404 to move in a circumferential direction. It is understood that the back plate 408 may include the elongated pin holes 602 and the seal shoe 404 may include the pin holes 420.

[0081] The seal shoe 404 includes a forward plate 1202 placed forward the first plate 438 of the seal shoe 404. A circumferential hollow forward pocket 1206 is defined between the forward plate 1202 and the first plate 438 and the protrusions 436. The front plate 412 is placed in the forward plate 1202. The front plate 412 includes a plurality of pin holes 420 for fixing the anti-rotation pins 440.

[0082] The seal segment 1200 includes a single piece U-shaped secondary seal 1208 having a forward plate 1210 and an aft plate 1212. The aft plate 1212 includes apertures 444 (not shown in FIG. 12) for receiving the fastener 418.

[0083] The configuration of the seal segment 1200 is otherwise corresponds to the configuration of the seal segment 400. Corresponding components of the seal segment 1200 are correspondingly labeled, which are not described in detail with respect to the seal segment 1200.

[0084] FIG. 13 illustrates an assembled view of the seal segment 1200. The front plate 412 is placed in the U-shaped secondary seal 1208 and placed in the forward pocket 1206. The fasteners 418 (not shown in FIG. 13) connect the front plate 412, the U-shaped secondary seal 1208, the seal carrier 402 coupled with the seal shoe 404, and the back plate 408. A sliding interface exists between the forward plate 1210 of the U-shaped secondary seal 1208 and the seal shoe 404 for reducing cooling air leakage between the seal carrier 402 and the seal shoe 404.

[0085] FIG. 14 illustrates an exploded view of a seal segment 1400. The seal segment 1400 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, a plurality of fasteners 418. The back plate 408 is a separate piece from the seal carrier 402. The back plate 408 includes a plurality of venting holes 902 for balancing pressure difference from the forward side to the aft side of the seal segment 900.

[0086] The coupling assembly 406 includes two identical seal springs 410. The two seal springs 410 are mirror imaged positioned at two circumferential ends of the seal segment 1400. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 at two circumferential ends of the seal segment 1400. Each seal spring 410 includes a first leg 454 and a second leg 456. Each seal spring 410 couples the seal shoe 404 to the seal carrier 402 by an engagement between the first leg 454 and the first keyhole slot 430 and an engagement between the second leg 456 and the second keyhole slot 446 similar as the seal segment 400.

[0087] The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the back plate 408. The fasteners 418 connect the seal carrier 402 from the front plate 412 to the back plate 408.

[0088] The seal shoe 404 has two protrusions 436 extending radially upward at two circumferential ends, respectively. The seal shoe 404 includes a solid central portion 1406 extending circumferentially between the protrusions 436. In operation of the gas turbine engine 100, the radial loads applied to the seal shoe 404 by the seal springs 410 are balanced between the protrusions 436.

[0089] The front plate 412 includes an indentation 1402 disposed at the aft side of the front plate 412 and at the radially inner position. The seal segment 1400 includes a seal strip 1404. The seal strip 1404 may include a U-shaped seal strip, or a chevron seal strip, or any types of seal strips known in the industrial.

[0090] The configuration of the seal segment 1400 is otherwise corresponds to the configuration of the seal segment 400. Corresponding components of the seal segment 1400 are correspondingly labeled, which are not described in detail with respect to the seal segment 1400.

[0091] FIG. 15 illustrates an assembled view of the seal segment 1400. The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the seal carrier 402.

[0092] The seal strip 1404 is disposed in the indentation 1402 and interface to the seal shoe 404. The seal strip 1404 provides secondary seal for the seal segment 1400.

[0093] FIG. 16 illustrates an exploded view of a seal segment 1600. The seal segment 1600 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, a plurality of fasteners 418. The back plate 408 is a separate piece from the seal carrier 402. The back plate 408 includes a plurality of venting holes 902 for balancing pressure difference from the forward side to the aft side of the seal segment 900.

[0094] The coupling assembly 406 includes two identical seal springs 410. The two seal springs 410 are mirror imaged positioned at two circumferential ends of the seal segment 1600. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 at two circumferential ends of the seal segment 1600. Each seal spring 410 includes a first leg 454 and a second leg 456. Each seal spring 410 couples the seal shoe 404 to the seal carrier 402 by an engagement between the first leg 454 and the first keyhole slot 430 and an engagement between the second leg 456 and the second keyhole slot 446 similar as the seal segment 400.

[0095] The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the back plate 408. The fasteners 418 connect the seal carrier 402 from the front plate 412 to the back plate 408.

[0096] The seal carrier 402 includes a notch 1602 disposed at the central portion 428. The notch 1602 has an opening at a radially inner surface of the central portion 428. The seal shoe 404 includes a key 1604 disposed at the pocket 452. The key 1604 protrudes radially outward. The key 1604 engages the notch 1602 for circumferential retention of the seal shoe 404. The engagement between the key 1604 and the notch 1602 allows the seal shoe 404 to rotate about its transverse axis. The key 1604 may have a keystone shape.

[0097] The seal segment 1200 includes an anti-rotation pin 440 for coupling the seal shoe 404 to the back plate 408. The back plate 408 includes a plurality of pin holes 420 for fixing the anti-rotation pins 440 with the sleeves 1204. The seal shoe 404 includes a plurality of elongated pin holes 602 that are elongated in a radial direction. The elongated pin holes 602 fit the anti-rotation pins 440 with the sleeves 1204 to allow the seal shoe 404 to move in the radial direction with respect to the seal carrier 402 and to restrict the seal shoe 404 to move in a circumferential direction. It is understood that the back plate 408 may include the elongated pin holes 602 and the seal shoe 404 may include the pin holes 420.

[0098] The front plate 412 includes an indentation 1402 disposed at the aft side of the front plate 412 and at the radially inner position. The seal segment 1600 includes a seal strip 1404. The seal strip 1404 is disposed in the indentation 1402 and interface to the seal shoe 404. The seal strip 1404 provides secondary seal for the seal segment 1600. The seal strip 1404 may include a U-shaped seal strip, or a chevron seal strip, or any types of seal strips known in the industrial.

[0099] The configuration of the seal segment 1600 is otherwise corresponds to the configuration of the seal segment 400. Corresponding components of the seal segment 1600 are correspondingly labeled, which are not described in detail with respect to the seal segment 1600.

[0100] FIG. 17 illustrates an exploded view of a seal segment 1700. The seal segment 1700 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, and a plurality of fasteners 418. The back plate 408 is an integral one piece with the seal carrier 402. The back plate 408 is integrally positioned at the aft side of the seal carrier 402.

[0101] The seal carrier 402 includes a plurality of earpieces 1702 extending radially inwardly. Each earpiece 1702 has an opening 1704 displaced at the center of the earpiece 1702. A first set of two earpieces 1702 is aligned in an axial row at one circumferential side of the seal carrier 402. A second set of two earpieces 1702 is aligned in the axial row at the other circumferential side of the seal carrier 402.

[0102] The seal shoe 404 has a first plate 438 and a second plate 442 extending circumferentially between two ends of the seal shoe 404. The first plate 438 and second plate 442 define a pocket 452 between two circumferential ends of the seal shoe 404. The pocket 452 reduces a weight of the seal shoe 404. The dynamics of the circumferential hollow shaped seal shoe 404 may be optimized with reduced weight. The seal shoe 404 includes a plurality of coupling pin hole 1710 disposed at the first plate 438 and the second plate 442.

[0103] The coupling assembly 406 includes two identical seal springs 410. The two seal springs 410 are mirror imaged positioned at two circumferential ends of the seal segment 1700. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 at the two circumferential ends of the seal segment 1700. Each seal spring 410 is a U-shaped leaf spring having a first leg 454 and a second leg 456. The first end of the seal spring 410 has a first cylindrical end 458 at an end of the first leg 454. The second end of the seal spring 410 has a second cylindrical end 460 at an end of the second leg 456. The coupling assembly 406 includes a plurality of first coupling pins 1706 and a plurality of second coupling pins 1708.

[0104] The front plate 412 includes a plurality of pin holes 420. The back plate 408 includes a plurality of pin holes 420. The seal shoe 404 includes a plurality of elongated pin holes 602 disposed at the first plate 438 and the second plate 442. The elongated pin holes 602 are elongated in the radial direction.

[0105] FIG. 18 illustrates the front plate 412 looking from the aft side. The front plate 412 includes a plurality of sleeves 1204 that are attached to the aft side surface 502 of the front plate 412. Each pin hole 420 extends from the forward side of the front plate 412 to each sleeve 1204 for receiving each anti-rotation pin 440. The sleeves 1204 also control an axial spacing between the front plate 412 and the back plate 408 but allowing for clamping by the anti-rotation pins 440.

[0106] FIG. 19 illustrates a section view of the seal segment 1700. The first leg 454 of the seal spring 410 is attached to the seal carrier 402 by inserting the first coupling pin 1706 through the first cylindrical end 458 of the seal spring 410 to the openings 1704 of the two earpieces 1702 aligned in the axial row of the seal carrier 402.

[0107] The second leg 456 of the seal spring 410 is attached to the seal shoe 404 by inserting the second coupling pin 1708 through the second cylindrical end 460 of the seal spring 410 to the coupling pin hole 1710 of the seal shoe 404.

[0108] FIG. 20 illustrates an assembled view of the seal segment 1700 with the front plate 412 removed. The first cylindrical end 458 of the seal spring 410 is disposed between the two earpieces 1702 of the seal carrier 402. The first coupling pin 1706 extends through the first cylindrical end 458 and the openings 1704 of the two earpieces 1702 for attaching the seal spring 410 to the seal carrier 402.

[0109] The second leg 456 of the seal spring 410 is disposed between the first plate 438 and the second plate 442 of the seal shoe 404. The second coupling pin 1708 extends through the second cylindrical end 460 and the coupling pin hole 1710 at the first plate 438 and second plate 442 for attaching the seal spring 410 to the seal shoe 404.

[0110] The seal shoe 404 is coupled to the back plate 408 by the anti -rotation pins 440 extending through the elongated pin holes 602 to the pin holes 420 at the back plate 408. The elongated pin holes 602 fit the anti-rotation pins 440 to allow the seal shoe 404 to move in the radial direction with respect to the seal carrier 402 and to restrict the seal shoe 404 to move in a circumferential direction.

[0111] FIG. 21 illustrates an exploded view of a seal segment 2100. The seal segment 2100 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406 including two seal springs 410, a back plate 408, a front plate 412, and a plurality of fasteners 418. The back plate 408 is a separate piece from the seal carrier 402. The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408.

[0112] The seal segment 2100 includes two seal strips 1404. One of the seal strip 1404 in the indentation 1402 of the front plate 412 and between the seal shoe 404 and the front plate 412. The other seal strip 1404 is disposed in the other indentation 1402 of the back plate 408 and between the seal shoe 404 and the back plate 408. The seal strips 1404 may include U-shaped seal strips or chevron seal strips, or any types of seal strips known in the industrial.

[0113] The seal carrier 402 includes two first fixing holes 2102 disposed at two circumferential end surfaces 2116 of the seal carrier 402, respectively. The seal shoe 404 includes two second fixing holes 2104 disposed at two circumferential end surfaces 2118 of the seal shoe 404, respectively.

[0114] The coupling assembly 406 two identical seal springs 410. The two seal springs 410 are mirror imaged positioned at two circumferential ends of the seal segment 2100. The two seal springs 410 couple the seal shoe 404 to the seal carrier 402 at the two circumferential ends of the seal segment 2100. Each seal spring 410 includes a first tab 2106 and a second tab 2108. The first tab 2106 is disposed at an end of the first leg 454. The second tab 2108 is disposed at an end of the second leg 456. Each of the first tab 2106 and the second tab 2108 includes a hole 2120. The coupling assembly 406 includes a plurality of first fixing pins 2110 and a plurality of second fixing pins 2112. The coupling assembly 406 includes a plurality of blocks 2114. Each block 2114 has a hole 2122 displaced at a center of the block 2114.

[0115] FIG. 22 illustrates a section view of the seal segment 2100. The first leg 454 of the seal spring 410 is attached to the seal carrier 402 by inserting the first fixing pin 2110 from the hole 2120 of the first tab 2106 to the first fixing hole 2102 at an end surface 2116 of the seal carrier 402. The block 2114 is disposed between the first tab 2106 and the first fixing pin 2110 to pass the first fixing pin 2110 through the hole 2122.

[0116] The second leg 456 of the seal spring 410 is attached to the seal shoe 404 by inserting the second fixing pin 2112 from the hole 2120 of the second tab 2108 to the second fixing hole 2104 at an end surface 2118 of the seal shoe 404. The block 2114 is disposed between the second tab 2108 and the second fixing pin 2112 to pass the second fixing pin 2112 through hole 2122.

[0117] FIG. 23 illustrates an assembled view of seal segment 2100. The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the seal carrier 402.

[0118] One seal strip 1404 is disposed between the front plate 412 and the seal shoe 404. The other seal strip 1404 is disposed between the seal shoe 404 and the back plate 408. The seal strips 1404 provide secondary seal for the seal segment 1600.

[0119] FIG. 24 illustrates an exploded view of a seal segment 2400. The seal segment 2400 includes a seal carrier 402, a seal shoe 404, a coupling assembly 406, a back plate 408, a front plate 412, and a plurality of fasteners 418. The back plate 408 is an integral one piece with the seal carrier 402. The back plate 408 is integrally positioned at the aft side of the seal carrier 402. The coupling assembly 406 couples the seal shoe 404 to the seal carrier 402. The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408 passing the apertures 444.

[0120] The seal carrier 402 includes a plurality of earpieces 1702 extending radially inwardly. Each earpiece 1702 has an opening 1704 displaced at the center. A first set of two earpieces 1702 is aligned in an axial row. A second set of two earpieces 1702 is aligned in the axial row and is spaced apart from the first set of two earpieces 1702 circumferentially along the seal carrier 402

[0121] The coupling assembly 406 includes two identical flat plates 2402. The two flat plates 2402 are positioned circumferentially spaced apart along the seal segment 2400. The first end of the flat plate 2402 has a first cylindrical end 458. The second end of the flat plate 2402 has a second cylindrical end 460. The coupling assembly 406 includes a plurality of first coupling pins 1706 and a plurality of second coupling pins 1708.

[0122] The seal segment 2400 includes a secondary seal 2404. The secondary seal 2404 is integrated to the aft side of the front plate 412.

[0123] FIG. 25 illustrates the seal shoe 404 looking from the aft side. The seal shoe 404 comprises a plurality of earpieces 1702 extending radially upwardly. Each earpiece 1702 has an opening 1704 displaced at the center of the earpiece 1702. A first set of two earpieces 1702 is aligned in an axial row. A second set of two earpieces 1702 are placed in the axial row and is spaced apart from the first set of two earpieces 1702 circumferentially along the seal shoe 404.

[0124] FIG. 26 illustrates a section view of the seal segment 2400. The first cylindrical end 458 of the flat plate 2402 is attached to the seal carrier 402 by inserting the first coupling pin 1706 through the openings 1704 of the set of two earpieces 1702 at the seal carrier 402. The second cylindrical end 460 of the flat plate 2402 is attached to the seal shoe 404 by inserting the second coupling pin 1708 through the openings 1704 of the set of two earpieces 1702 at the seal shoe 404.

[0125] FIG. 27 illustrates an assembled view of the seal segment 2400. The fasteners 418 connect the seal carrier 402 coupled with the seal shoe 404 between the front plate 412 and the back plate 408. The front plate 412 is placed at the forward side of the seal carrier 402. The back plate 408 is placed at the aft side of the seal carrier 402.

[0126] The secondary seal 2404 is disposed between the front plate 412 and the seal shoe 404. A sliding interface exists between the secondary seal 2404 and the seal shoe 404 which creates the secondary seal for reducing cooling air leakage between the seal carrier 402 and the seal shoe 404. The secondary seal 2404 is integrated to the front plate 412. A separated secondary seal is thus eliminated.

[0127] The proposed non-contact seal assembly 300 provides a coupling assembly 406 for coupling the seal shoe 404 to the seal carrier 402. The coupling assembly 406 is a separate piece from the seal shoe 404 that allows an easy removal, repair, or upgrade of the coupling assembly 406. This also allows the non-contact seal assembly 300 to be tuned at flow test. The proposed non-contact seal assembly 300 simplifies the design and manufacture of the non-contact seal assembly 300.

[0128] The seal springs 410 of the coupling assembly 406 of the proposed non- contact seal assembly 300 couples the seal shoe 404 to the seal carrier 402 at two circumferential ends of the seal carrier 402. Such arrangement allows the radial loads applied to the seal shoe 404 by the seal springs 410 to be balanced between the two circumferential ends of the seal carrier 402 to reduce tilt of the seal shoe 404 in operation of the gas turbine engine 100. [0129] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0130] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.