Plunger seal assembly and sealing method

In some embodiments, apparatuses are provided herein useful to sealing a gap between a movable flap and stationary structure, such as a gap between a gas turbine engine nozzle flap and sidewall. An apparatus for sealing such a gap may be a plunger seal which may include a plurality of plunger segments connected together using at least one flexure. When positioned in the gap, the flexures within the plunger segments pivot allowing rotation of each of the plurality of plunger segments about their respective pivot point, such that the plunger assembly seals and contours against the movable surface.

TECHNICAL FIELD

This technical field relates generally to seals for sealing a gap between a stationary structure and contoured wall or movable surface component. More specifically, the invention relates to plunger seal assemblies and methods for preventing air leakage in applications including, but not limited to, gas turbine engine exhaust nozzles.

BACKGROUND

A gas turbine engine, such as a gas turbine engine for powering an aircraft, may include an exhaust nozzle downstream of the turbine. The exhaust nozzle may include a movable flap positioned between the nozzle sidewalls. The flap may be actuated via a series of linkages to control a two-dimensional area within the nozzle to direct and accelerate the flow of core air from the engine for the purpose of thrust.

Gaps between the flap and the nozzle sidewalls may create channels through which core air may flow, for example, due to a pressure gradient between the nozzle core and ambient environment surrounding the nozzle. Leakage of core air from the nozzle core to the ambient environment may reduce the thrust and efficiency of the engine.

DETAILED DESCRIPTION

To reduce the size of gaps between the flap and the nozzle sidewalls and to seal core air within the nozzle core, a seal assembly may be positioned between the nozzle flap and sidewall. In some instances, liners may be mounted to the nozzle sidewalls via one or more hangers. When the nozzle sidewall includes a liner, a seal assembly may be positioned between the flap and the sidewall liner, such that the seal seals against the sidewall liner rather than directly to the nozzle sidewall. Liners, including sidewall liners may distort, contour and warp during operation, and thus are not flat or of a consistent profile.

During operation of the nozzle, the flap may move in one or more directions relative to the nozzle sidewall. Thus, the seal assembly for the gap between the flap and the nozzle sidewall may need to accommodate for sliding motion. For example, the seal assembly may need to facilitate the sliding of the seal assembly along the nozzle sidewall while still maintaining a seal between the nozzle flap and sidewall. As such, the seal assembly may need to conform to the nozzle sidewall and/or liner when the nozzle sidewall and/or the liner, or portions thereof, distort or move.

Conventional plunger seals have a number of disadvantages. In general, they are rigid and extremely sensitive to wear and tear. In addition, known plungers typically have a substantial tradeoff between the conformability of the seal against a surface and the seal's effectiveness and reliability. Therefore, there remains a desire to have a plunger seal assembly that seals a movable or contoured surface such as a nozzle flap and/or sidewall more effectively and efficiently than known methods.

A plunger seal assembly or apparatus and sealing method for sealing a dynamic gap in which there is a need to seal air from between a stationary structure and a movable surface or wall is provided herein. The plunger seal assembly comprises a number of plunger segments linked together using flexure elements bonded to the segments in a manner that allows the segments to move and conform to the movable surface. More specifically, the flexures and their placement between plunger segments allows each segment to relate to its neighboring plunger segments consistently and determinately without segment-to-segment leakage variation, binding, and unintended seal motion.

The flexures, each of which are coupled to an inner surface of two neighboring segments, are configured to pivot about a centroid (i.e., a virtual intersection of the flexure ligaments) such that a head of the flexure coupled to a respective segment allows the segment to seal against the movable wall as it contours, without interfering with the pivoting movement of the neighboring segments. The placement of each flexure is configured to allow a predetermined amount of space between segments to avoid potential binding or excessive gapping between plunger segments. The number of segments used within embodiments of the plunger assemblies herein may vary depending on a given application. More particularly, the number of segments used may be balanced relative to the amount of conformity required and a maximum amount of acceptable leakage between plunger segments.

FIG.1is an illustration of a nozzle assembly10within a gas turbine engine12that is provided herein as an exemplary application in which the plunger seal apparatuses and sealing methods provided herein may be employed. The apparatuses and methods are not limited to gas turbine engines and may be suitable for other applications that require sealing of high motion, high conformability surfaces, particular, and high temperatures, where elastomeric seals are not viable.

The plunger seal assembly and sealing methods provided herein overcome many of the challenges of conventional solutions. For example, because of the segmented configuration, targeted placement of the flexure elements between neighboring segments, and various other features, the embodiments herein minimize leakage. This leakage may have otherwise occurred, for example, via horizontal compression between neighboring plunger segments, lateral stack binding, and/or gapping of one or more plunger segments away from the contoured surface in a given dynamic gap application. These and other benefits and advantages will be discussed herein.

With reference toFIGS.1-4, the gas turbine engine12is illustrated that produces core air flow. At the aft of the gas turbine engine12is a nozzle assembly10to control the effect of the discharged core air. The nozzle assembly10includes upper and lower flaps14mounted for movement relative to one another between two opposing sidewalls16. A gap42is located between outer edges of the flaps14and the sidewalls16. This gap42would allow air to exhaust inefficiently to the ambient surroundings without seals. The gas turbine engine12discharges exhaust gases, also referred to as core air, into the nozzle assembly10. The nozzle assembly10may include one or more flaps14and one or more sidewalls16. In this exemplary embodiment, the nozzle assembly10includes two opposing, sidewalls16and two opposing, flaps14. In some embodiments, one or more of the sidewalls16further include a liner18mounted to the sidewall via one or more hangers20. The flaps14may be movable relative the sidewalls16, which may be generally stationary. By some approaches, the flaps14may be pivotally supported by the gas turbine engine12at a fore end30of the nozzle assembly10. The flaps14may be pivotally supported, for example, by rotating means such as hinges24that couple the flaps14to the gas turbine engine12.

The flaps14and sidewalls16define a nozzle core22that bounds core air exiting the gas turbine engine12. Core air from the gas turbine engine12flows through the nozzle core22to create thrust for the gas turbine engine12. Core air may flow through the nozzle core22from the fore end30to an aft end32of the nozzle assembly10. The aft end32of the nozzle assembly10defines an outlet26, which is generally rectangular, for discharging core air from the nozzle assembly10to the ambient environment. In some approaches, the flaps14are movable to direct the flow and pressure of core air within the nozzle core22. For example, the flaps14may be vertically movable to adjust the size of the outlet26of the nozzle assembly10.

Turning toFIG.2, an engine core34of the gas turbine engine12is upstream of the nozzle assembly10such that core air flows from the engine core34into the nozzle core22. In some embodiments, the flaps14of the nozzle assembly10are actuated to vary the one or more cross-sectional areas of the nozzle core22. In this manner, the nozzle assembly10is a variable two-dimensional nozzle assembly. The flaps14may be actuated, for example by pivoting about the hinges24. The nozzle core22includes a first cross-sectional area36, a second cross-sectional area38, and a third cross-sectional area40. The flaps14control the size of the second cross-sectional area38and the third cross-sectional area40.

During operation of the gas turbine engine12, the flaps14create a pressure gradient in the nozzle core22of the nozzle assembly10. For example, pressure of the core air in the nozzle core22decreases from the fore end30to the aft end32of the nozzle core22. That is, the pressure of the core air decreases from the first cross-sectional area36to the second cross-sectional area38to the third cross-sectional area40. The two-dimensional cross-section allows for different nozzle packaging and more readily adjustable cross-sectional areas36,38,40for matching both thrust and operability across the entire range of engine operating conditions.

Turning toFIG.3, the gap42between the flap14and the sidewall16extends along the length of the flap14(i.e., from the fore end30to the aft end32of the nozzle assembly as shown inFIG.1). The gap42may be continuous or interrupted at one or more locations. The size of the gap42may vary dynamically during operation of the nozzle assembly10. During operation, the flaps14may move along the Y-direction shown inFIG.3. This motion of the flaps14, for example, varies the size of the outlet26of the nozzle assembly10. Additionally, during operation, the sidewall16may shift along the X-direction shown inFIG.3. For example, the pressure of core air in the nozzle core22may urge the sidewall16away from the flap14, increasing the size of the gap42. Accordingly, the gap42may be narrower when the nozzle core22is at atmospheric pressure than when the nozzle core22receives engine core air during operation of the nozzle assembly10. In addition to motion of the sidewall16, the liner18of the sidewall16may also distort during operation, causing the liner18to shift along one or more of the X-direction and Y-direction. Such distortion of the liner18may occur, for example, due to changes in temperature and pressure along the nozzle core22. A plunger seal assembly50(not shown inFIG.3) may be installed in the gap42between the flap14and the sidewall16. In some embodiments, the plunger seal assembly50is the plunger seal assembly50depicted inFIGS.5-9.

With reference toFIG.4, the gap42extends generally between the flap14and the sidewall16. In the nozzle assembly10, the sidewall16includes the liner18, which is mounted to the sidewall16via the hangers20. Accordingly, the gap42extends between the flap14and the liner18. The flap14may further include a flap liner46positioned at an end of the flap14adjacent the nozzle core22. The flap liner46, or portions thereof, may extend into the gap42. The nozzle assembly10includes a plunger seal assembly50positioned in the gap42between the flap14and the sidewall16. The plunger seal assembly50bridges the gap42between the flap14and the sidewall16to seal the gap42. The plunger seal assembly50may reduce the size of the gap42or eliminate the gap42. In this manner, the plunger seal assembly50reduces the excursion of core air from the nozzle core22through the gap42which may decrease or effect the flow of core air from the nozzle core22to the ambient environment surrounding the nozzle assembly10.

Turning toFIGS.5and6, the plunger seal assembly50is shown in more detail including in the illustrated example that the plunger seal assembly50has a plurality of plunger segments51. The plunger segments51include a first plunger segment52, a second plunger segment54, a third plunger segment56, and a fourth plunger segment58. For simplicity, we will describe the relationship between the first plunger segment52, the second plunger segment54, and the third plunger segment56. As illustrated, the second plunger segment54includes a hollow body54bdefining an interior54a, a proximal end54pand a distal end54d, wherein the distal end54dis spaced from the proximal end54p. The first plunger segment52is located at the proximal end54pof the second plunger segment54and the third plunger segment56located at the distal end54dof the second plunger segment54. The second plunger segment54may be provided having a columnar geometry defined by an upper wall, a lower wall, two sidewalls (e.g., sidewall81), and a channel or void defined therein as illustrated. However, other suitable geometries are also envisioned. The fourth plunger segment58is located at a distal end56dof the third plunger segment56. Though not shown inFIGS.5and6, it is contemplated that additional plunger segments may be coupled to the fourth plunger segment58.

The number of plunger segments51of the plunger seal assembly50and the dimensions of the first plunger segment52, the second plunger segment54, the third plunger segment56, and the fourth plunger segment58may be selected based on the dimensions of a specific gap42and that needs to be sealed. In an embodiment, for example, the plunger segments51may have identical dimensions suitable for a given application. In some embodiments, the plunger segments51have different dimensions. However, even in embodiments where the plunger segments51do not have identical dimensions, the flexural radius and interface curvature, as illustrated by arrow79inFIG.9, between neighboring plunger segments must be identical. The features and benefits described may be applied to each of the plunger segments51. Further still, while each of the plunger segments51has been illustrated and described as being identical or substantially identical it is contemplated that they need not be. When the plunger segments51are operably coupled together end to end, respectively, as described herein, the respective interiors of the plunger segments51form a plunger channel63.

The plunger segments51may be formed of a metallic or ceramic alloy material. The plunger segments51may be traditionally machined, stamped MIM, Cast, EDMed, additively grown, or otherwise manufactured using any appropriate industrial fabrication method.

The plunger segments51are coupled or interlocked lengthwise using a plurality of flexural support elements or flexural pivots (e.g., flexures60,62,64,66, respectively) coupled thereto. When the plunger segments51are coupled or interlocked lengthwise the plunger channel63is created. The flexures60,62,64,66are referred to herein as flexures for simplicity. In the illustrated embodiment, flexures60,62,64,66have a hairpin or wishbone shape having a head41and two extending arms, ligaments or stems (e.g., stems43,45) as illustrated inFIGS.5-9. The flexures60,62,64,66may have other configurations, profiles, shapes, or designs, (not shown) including by way of further non-limiting examples triangular, trapezoidal, butterfly, biaxal, etc. Further still, while each of the flexures has been illustrated and described as being identical or substantially identical it is contemplated that they need not be.

As illustrated inFIG.6, the flexure60is coupled to the first plunger segment52and the second plunger segment54. (For purposes of illustration, the upper walls of the plunger segments51are not shown inFIG.6in order to provide visibility to the flexure60and the flexure62within the plunger channel63.) As such, each flexure60,62,64,66may be coupled to an inner surface as defined by the interior54aof the hollow body54bof its two neighboring plunger segments at multiple points or interfaces83a,83b,83c. For example, the flexure60has three bonding pads60a,60b,60c. As shown, the head bonding pad60ais coupled to the interior54aof the second plunger segment54towards its distal end54dat interface83c. The two stem bonding pads60b,60care secured to the interior52aof neighboring plunger segment52at interface83aand interface83b. Similarly, flexure62also three bonding pads62a,62b,62c. Head bonding pad62ais coupled to an interior56aof the third plunger segment56towards its distal end56d. The two stem bonding pads62b,62care coupled to the interior54aof the second plunger segment54. Vertical sidewall81is the exterior surface or portion of the plunger seal assembly50in contact with the sidewall16inFIG.8.

The methods of coupling the flexures60,62,64,66to the plunger segments51herein may vary based on a type of flexure material and/or plunger material used. Suitable methods may include, for example, bonding, soldering, welding, braising, or other adhesive coupling or mechanical attachment methods. As such, interfaces83a,83b,83cmay include adhesive or other bonding materials depending on the method of coupling used.

The flexures (e.g., flexures60,62) utilized in the embodiments of the plunger seal assembly50are coupled in a nested fashion within the plunger channel63. This placement enables maintains a precise frictionless gap or space (e.g., predetermined spaces77a,77b,77c) between a given plunger segment and its neighboring plunger segments. While not apparent in the figures, predetermined space77ais present between the first plunger segment52and the second plunger segment54. Predetermined space77bis present between the second plunger segment54and the third plunger segment56. Similarly, predetermined space77cis present between the third plunger segment56and the fourth plunger segment58. The enlarged view inFIG.7illustrates the predetermined space77b. In some approaches, the predetermined spaces77a,77b,77care substantially uniform. That is, the predetermined spaces77a,77b,77care substantially equidistance along their length.

In addition, in an embodiment, the stem bonding pads60b,60cof one or more flexures (e.g., flexure60) may be coupled to both the lower inner surface73aof the first plunger segment52, as well as the inner sidewalls73b,73c, respectively. In this way, the stem bonding pads60b,60care further secured to the first plunger segment52. The strength of the bonding or coupling of the bonding pads60a,60b,60cto the plungers at the respective interfaces83a,83b,83cmay be increased as necessary to ensure proper operation of the plunger seal assembly50. In operation, the flexures60,62,64,66create a restorative force that resists the hinging motion of the plunger seal assembly50and must be designed in conjunction with the pressure, preload springs/actuators to provide sufficient driving force for actuation.

FIG.8illustrates a cross-sectional view of an embodiment of a plunger seal assembly50for sealing air from the nozzle core22seeking to pass through the gap42. The flexure60is disposed within the plunger channel63, along a plane in the z direction. In an embodiment, the first plunger segment52may be disposed within a seal housing72. The seal housing72may be a removable or integral part of a flap (e.g., the flap14inFIGS.1-4) that provides a tightly controlled interface for the plunger seal assembly50to slide in and out of, as well as secondary retention to prevent the plunger seal assembly50from falling out on disassembly. The seal housing72may be a tightly controlled opening or slot85. The faying surfaces within the slot85that interface with the plunger seal assembly50may or may not be coated for wear, friction, thermal, or chemical benefit. In addition, the plunger seal assembly50may interface with the slot85and the sidewall16to create pressure gradients that load at least a portion of the plunger seal assembly50into the seal housing72and maintain a seal against the sidewall16.

In this embodiment, the first plunger segment52, as part of a plunger seal assembly50(the remainder of which is not visible) seals against core air from the nozzle core22seeking to pass through gap42into the ambient surroundings. However, the sidewall16may also correspond to other applications requiring an airtight seal along an analogous contoured or movable surface.

FIG.9further depicts the location of a plurality of pivot points76a,76b, and76ccorresponding to the flexures60,62,64, respectively, within the plunger segments51. Pivot points76a,76b,76clocated at the centroid or projected intersection of the stems of a given flexure (see dotted lines inFIG.9). For example, pivot points76a,76b,76care the location about which a head (e.g., bonding pad60a, bonding pad62a) of the flexures60,62,64rotates to allow at least one of the plunger segments51to move and conform relative to the movement of the sidewall16. The placement of each of the flexures60,62,64is provided such that there is a minimal distance between neighboring segments. The predetermined spaces77a,77b,77care provided between the plunger segments51to facilitate this. For example, when the sidewall16moves the first plunger segment52, the flexure60pivots about pivot point76a, such that the second plunger segment54is not interfered with. Similarly, flexure62pivots about point76bsuch that neither the third plunger segment56nor the first plunger segment52are interfered with when the sidewall16moves adjacent the second plunger segment54.

The location of the attachment of a given head bonding pad (e.g., bonding pad60a, bonding pad62a) enables the plunger seal assembly50to maintain the predetermined spaces77a,77b,77cbetween the plunger segments51. The plunger segments51are interlocked in a repeating pattern so that each of the plunger segments51in the plunger seal assembly50is not able to move beyond a predefined distance during contouring or movement of the sidewall16. For example, the second plunger segment54is interlocked with the first plunger segment52and the third plunger segment56so that the second plunger segment54cannot move beyond a predefined distance from the first plunger segment52and the third plunger segment56.

The geometry (more or less acute, longer vs shorter ligaments, etc.) of the flexures (e.g., flexures60,62,64,66) in the embodiments herein are selected to provide a desired maximum amount of rotation before clashing. In other words, each flexural stem will contact its respective plunger segment and clash if the plunger segment is over-flexed, leading to disrupted operation of the plunger seal assembly50. As such, in some aspects, a ratio between the extended distance and the retracted distance of each of the flexures60,62,64,66is low. By selecting the geometry appropriately, the plunger seal assembly50will increase the pressure balance when inserted into a slot against the sidewall16.

In addition, the flexure placement enables movement of the entire plunger seal assembly50relative to the sidewall16, without the wear and tear, stack binding, or gapping that might occur in other conventional stacked seal assemblies (e.g., hinged wafer assemblies).

FIG.10is a perspective view of a plunger seal assembly50similar to that shown and described inFIG.5for sealing against the sidewall16. It will be understood that the illustrated plunger seal assembly50has been shown with additional plunger segments and corresponding flexures. It is contemplated that any suitable number of plunger segments and flexures may be used and, further, that the plunger seal assembly50may be any length.

The selection of materials for each of the flexures60,62,64,66depends on the operational temperature of the specific application in which the plunger seal assembly50is required. In one non-limiting operational example, the flexures60,62,64,66may be formed of a metallic or ceramic alloy capable of withstanding temperatures greater than or equal to 500-2000 degrees Fahrenheit, which corresponds to the operational temperature of a gas turbine engine whose nozzle is depicted inFIGS.1-4. The combination of flexure materials and plunger segments materials are selected based on an amount of desired or acceptable leakage variation. For example, if sealing at only one temperature is required and compensated for by matching geometric gaps with thermal growth of the flexures60,62,64,66, high and low alpha materials could be interchanged without adverse effect. However, in applications where the plunger seal assembly50must operate over a large range of temperatures, the flexure materials and the plunger segment materials should be selected to have a similar coefficient of expansion. In the latter example, materials for the flexures60,62,64,66and the plunger segments51would be selected such that the gap between the plunger segments51does not close or open too much throughout the operational temperature range. For example, but not limited to, two nickel super alloys like Rene77and Inconel718plus have similar alphas across a broad range of temperatures and may meet the requirements of the design. Many other material matches can be chosen should their thermal growth and material properties sufficiently match the operating conditions required. Materials selection in accordance with these principles provides the benefit of avoiding any wanted growth of the plunger segments51relative to the flexures60,62,64,66when the plunger seal assembly50is exposed to heat, thereby minimizing leakage.

In some embodiments, preloaded springs or actuators may be used to supplement, augment, or replace a pressure load for some operational conditions. For example, when the gas turbine engine12is off, there is no pressure to drive the plunger seal assembly50into position. Accordingly, an actuation mechanism such as a spring behind each plunger segment, or intermittent plunger segments may be used to nudge or ensure sufficient contact between the plunger segments51and the sidewall16when the pressure differential is not sufficient.

FIG.11illustrates an actuated plunger seal assembly50a, in accordance with some embodiments. The actuated plunger seal assembly50aincludes an actuation mechanism80a. The actuation mechanism80amay be, for example, a spring or a plunger assembly. The actuation mechanism80ais disposed in the slot85between the plunger segment52aand the seal housing72. The actuation mechanism80aurges the first plunger segment52toward the sidewall16to seal the gap42.

FIG.12is a flow chart diagram of a method100of sealing a gap between a stationary structure and a movable surface. The method100includes positioning, at102, the plunger seal apparatus within the gap against the movable surface. The plunger seal apparatus includes a plurality of plunger segments interconnected using a plurality of flexures. The flexures are bonded at multiple points within an inner surface of each of the plunger segments such that a head of each flexure is configured to rotate about a pivot point corresponding to an arc of a corresponding one of the plurality of plunger segments. The method100further includes sealing the gap, at104, by allowing rotation of each of the plurality of plunger segments about their respective pivot points, such that the plunger assembly contours relative to the movement of the movable surface.

It is contemplated that the plunger seal assembly50may be installed in any gap between a movable flap and stationary structure or against any movable surface. Further, it is to be understood that the plunger seal assembly50is not limited to use in the nozzle assembly10but may be used to create a seal for any pressurized environment.

A plunger seal apparatus for sealing a gap, the plunger seal apparatus comprising: a first plunger segment having a first proximal end, a first distal end, and a first channel defined therein; a second plunger segment having a second proximal end, a second distal end, and a second channel defined therein; and a first flexure secured within the first channel and the second channel for coupling the first plunger segment to the second plunger segment, a placement of the first flexure defining a predetermined distance between the first distal end and the second proximal end and forming a plunger channel through the first channel and the second channel.

The plunger seal apparatus of any preceding clause, wherein the first flexure has a head portion coupled to the first plunger segment and two stem portions coupled to an inner surface of the second plunger segment.

The plunger seal apparatus of any preceding clause, wherein the head portion of the first flexure is configured to pivot about a centroid located within a third plunger segment, the third plunger segment located adjacent to the first plunger segment.

The plunger seal apparatus of any preceding clause, wherein the first flexure, the first plunger segment, and the second plunger segment are each comprised of at least one of a metallic material and a ceramic material.

The plunger seal apparatus of any preceding clause, further comprising a seal housing disposed within the gap and enclosed about a portion of the first plunger segment and the second plunger segment.

The plunger seal apparatus of any preceding clause, further comprising an actuation mechanism adjacent to at least one of the first plunger segment and the second plunger segment to urge at least one of the first plunger segment and the second plunger segment towards a stationary structure at least partially defining a gap.

The plunger seal apparatus of any preceding clause, wherein the plunger seal apparatus is configured to operate in temperatures between 500 and 2000 degrees Fahrenheit.

An exhaust nozzle for an engine comprising: a sidewall; a movable flap adjacent the sidewall; and a plunger seal apparatus disposed between the stationary sidewall and the movable flap to seal a gap between the sidewall and the movable flap, the plunger seal apparatus being configured to contour along at least a portion of the movable flap when the exhaust nozzle is in operation, the plunger seal apparatus comprising: a plurality of flexures; and a plurality of plunger segments, including at least a first plunger segment and a second plunger segment, the first plunger segment being coupled to the second plunger segment via at least one of the plurality of flexures, and wherein the plurality of plunger segments are connected end to end such that a channel is defined within the plunger seal apparatus.

The exhaust nozzle of any preceding clause, wherein each of the plurality of flexures comprises a head and two stem portions secured within neighboring plunger segments.

The exhaust nozzle of any preceding clause, wherein a pivot point of a given flexure within the plurality of flexures is located in a centroid within a neighboring plunger segment that is different than a plunger segment in which the head is secured.

The exhaust nozzle of any preceding clause, wherein the plurality of plunger segments are located at a predetermined distance between each other based on a placement of the plurality of flexures coupled thereto.

The exhaust nozzle of any preceding clause, wherein a material of the plurality of flexures is comprised of at least one of a metallic material and a ceramic material; and wherein a material of the plurality of plunger segments is comprised of at least one of a metallic material and a ceramic material.

The exhaust nozzle of any preceding clause, wherein the first plunger segment is further coupled to a third plunger segment using another one of the plurality of flexures.

The exhaust nozzle of any preceding clause, wherein the plurality of plunger segments comprise at least one of a plurality of machined plunger segments, plurality of stamped plunger segments, plurality of casted plunger segments, and plurality of additively manufactured plunger segments.

A method of sealing a gap, the method comprising: positioning a plunger seal apparatus within the gap against the movable surface, the plunger seal apparatus having a plurality of plunger segments interconnected using a plurality of flexures, the flexures being coupled at multiple points to an inner surface of the plurality of plunger segments such that a head of each flexure is configured to rotate about a pivot point located within a neighboring plunger segment; and sealing the gap by allowing rotation of at least some of the plurality of plunger segments about their respective pivot points, such that the plunger assembly contours against at least a portion of the movable surface when moving.

The method of any preceding clause further comprising defining a predetermined distance between each of the plurality of plunger segments using the plurality of flexures.

The method of any preceding clause, wherein the predetermined distance is substantially uniform between each of the plurality of plunger segments.

The method of any preceding clause, wherein the plurality of flexures are coupled to the inner surface of the plurality of plunger segments using at least one of bonding, soldering, welding, braising, and adhesive methods.

The method of any preceding clause, wherein the plurality of plunger segments are fabricated using at least one of a machining process, a stamping process, a casting process, and an additive manufacturing process.

The method of any preceding clause, wherein the plunger seal apparatus is configured to operate in temperatures between 500 and 2000 degrees Fahrenheit.

It will be understood that various changes in the details, materials, and arrangements of parts and components which have been herein described and illustrated to explain the nature of the dynamic seals between moving components and stationary components may be made by those skilled in the art within the principle and scope of the appended claims. Furthermore, while various features have been described with regard to particular embodiments, it will be appreciated that features described for one embodiment also may be incorporated with the other described embodiments.