Patent Description:
In turbomachinery, such as a gas turbine engine, a number of combustion chambers combust fuel mixed with compressed air, and a hot working gas flowing from these combustion chambers is passed via respective transitions (also referred to by some in the art as ducts and tail tubes) to respective entrances of a turbine stage of the engine. More specifically, a plurality of combustion chambers may be arranged radially about a longitudinal axis of the gas turbine engine, and likewise radially arranged transitions comprise outlet ends that converge to form an annular inflow of working gas to the turbine stage entrance. Each transition exit is joined by a number of seals each of which bridges a gap between a portion of the exit and one or more turbine components, such as turbine vane carrier. A number of factors --such as adjacent component growth, variances due to thermal expansion, mechanical loads, vibrational forces from combustion dynamics, etc.-- can present challenges regarding durability and performance of such seals.

Disclosed embodiments offer an improved technical solution for a sealing arrangement in a gas turbine engine. See <CIT> and <CIT> for examples of transition ducts for a gas turbine involving seal apparatuses. Further, US patent <CIT> shows a gas turbine engine arcuate segment with a leaf seal assembly. The leaf seal assembly includes a plurality of radially extending tabs circumferentially spaced apart from each other. Further, <CIT> discloses a turbomachine which includes a seal device for sealing a gap between two components, with a plurality of sealing elements tippable in the direction of a relative displacement of the components. In <CIT> a turbine system is described which includes a flexible metallic seal contacting an interface member to provide a seal between the interface member and a turbine section. Furthermore, <CIT> discloses a system for sealing a gap between a transition exit frame and a vane rail at a turbine inlet. The system includes a seal with a compliant seal member having a generally u-shaped profile to provide a sealing function in an axial direction.

According to the present invention a sealing arrangement to seal a gap between a first turbine component and a second turbine component in a gas turbine engine claimed in claim <NUM>, is provided.

Disclosed sealing arrangements provide substantial design flexibility since such sealing arrangements can reliably provide appropriate sealing functionality under various thermo-mechanical load scenarios that can routinely develop during operation of the gas turbine engine while enabling multiple degrees of freedom effective to accommodate radial and/or axial displacements that can develop between the first turbine component and the second turbine component and maintain such sealing joint.

The inventors of the present invention have recognized some practical limitations regarding certain known sealing designs that have been used to seal a gap between components in a gas turbine engine. Often, such known sealing designs may involve relatively thick (i.e., relatively stiff), metal strip seal segments, where at least some of the seal segments may overlap over one another to close the gap, and, in theory, should smoothly slide over one another to, for example, accommodate relative motion between the turbine components. However, in actual operation in the hot-temperature, high-vibration of the gas turbine engine, there may be substantial misalignments that can develop between the various seal segments, which may then interfere with one another, and may eventually bind causing premature wear of the sealing surfaces. This misalignment may be caused by various reasons, such as assembly tolerances, relative thermal growth, and deformation under thermo-mechanical loads and/or vibration. Regardless of the specific reason for the misalignment, it will be appreciated that such known seal designs tend to suffer from high rates of leakage under such misalignment conditions.

In view of such recognition, the present inventors propose an innovative technical solution for a sealing arrangement. Disclosed embodiments, in a cost-effective and reliable manner, make use of feather seals responsive to a pressure differential that develops across the gap to form a pressure-loaded sealing joint having multiple degrees of freedom, such as can effectively accommodate axial and radial (e.g., saw-toothing) relative motion between adjacent row one vane segments in a gas turbine.

Disclosed feather seals may involve a multi-ply construction (comprising relatively thin metal plies that, without limitation, may range in thickness from approximately <NUM> to approximately <NUM> to achieve appropriate flexibility) to form the pressure-loaded sealing joint. These thin plies can be joined in a straightforward manner to form a relatively flexible sealing arrangement effective to reduce leakage rates by ensuring a substantially uniform sealing surface contact under various thermo-mechanical load scenarios. The joining of these thin plies may be performed by way of suitable joints, such as, without limitation, bonding joints, welding joints, brazing joints, etc..

Disclosed embodiments are conducive to manufacturing-friendly and time-efficient operations that substantially improve manufacturability, dimensional accuracy and repeatability, and reduce costs. Without limitation, disclosed embodiments are effective to provide low-levels of stress under temperature gradients experienced during operation of the gas turbine engine. Accordingly, disclosed embodiments are expected to show an improved life relative to known seal designs, thereby reducing the requirement of replacement over the life of the gas turbine. This should reduce the cost of maintenance, and economic losses that otherwise would be endured due to downtime of the gas turbine engine. Disclosed embodiments providing longer life should in turn incrementally reduce the operating cost of the gas turbine over its entire life-cycle.

In the following detailed description, various specific details are set forth in order to provide a thorough understanding of such embodiments. However, those skilled in the art will understand that disclosed embodiments may be practiced without these specific details that the aspects of the present invention are not limited to the disclosed embodiments, and that aspects of the present invention may be practiced in a variety of alternative embodiments. In other instances, methods, procedures, and components, which would be well-understood by one skilled in the art have not been described in detail to avoid unnecessary and burdensome explanation.

Furthermore, various operations may be described as multiple discrete steps performed in a manner that is helpful for understanding embodiments of the present invention. However, the order of description should not be construed as to imply that these operations need be performed in the order they are presented, nor that they are even order dependent, unless otherwise indicated. Moreover, repeated usage of the phrase "in one embodiment" does not necessarily refer to the same embodiment, although it may. It is noted that disclosed embodiments need not be construed as mutually exclusive embodiments, since aspects of such disclosed embodiments may be appropriately combined by one skilled in the art depending on the needs of a given application.

The terms "comprising", "including", "having", and the like, as used in the present application, are intended to be synonymous unless otherwise indicated. Lastly, as used herein, the phrases "configured to" or "arranged to" embrace the concept that the feature preceding the phrases "configured to" or "arranged to" is intentionally and specifically designed or made to act or function in a specific way and should not be construed to mean that the feature just has a capability or suitability to act or function in the specified way, unless so indicated.

Several non-limiting terms may be used throughout this disclosure to facilitate explaining structural and/or functional interrelationships between components within the turbine engine, and thus it may helpful to define this terminology to establish a common understanding. Accordingly, these terms and their definitions, unless stated otherwise, are as follows. The terms "forward" and "aft" or "aftward" or similar, without further specificity, refer to the direction toward directions relative to the orientation of the gas turbine. Accordingly, "forward" refers to the compressor end of the engine, while "aftward" refers to the direction toward the turbine end of the engine. Each of these terms, thus, may be used to indicate movement or relative position along a longitudinal central axis of the machine or a component therein. The terms "downstream" and "upstream" are used to indicate position, such as within a given conduit relative to the general direction of a flow moving through it. As will be appreciated, these terms reference a direction relative to the direction of flow expected through the given conduit during normal operation, which should be plainly apparent to those skilled in the art. As such, the term "downstream" refers to the direction in which the fluid is flowing through the given conduit, while "upstream" refers to the opposite of that. Thus, for example, the primary flow of working fluid through a gas turbine, which begins as an air flow moving through the compressor and then becomes a flow of combustion gases within the combustor and beyond, may be described as beginning at an upstream location, at an upstream or forward end of the compressor and flowing downstream eventually toward a location at a downstream or aftward end of the turbine.

Additionally, the term "radial" refers to a movement or position perpendicular to an axis. For example, in certain situations it may be desirable to describe relative distance from a central axis, for example. In this case, for example, if a first component resides closer to the central axis than a second component, the first component will be described as being either "radially inward" or "inboard" of the second component. If, on the other hand, the first component resides further from the central axis than the second component, the first component will be described herein as being either "radially outward" or "outboard" of the second component. Additionally, as will be appreciated, the term "axial" refers to movement or position parallel to an axis, and the term "circumferential" refers to movement or position around an axis. While these terms may be applied in relation to a common central axis that may extend through the compressor and turbine sections of the engine, it should be appreciated that these terms may also be used in relation to other components or sub-systems of the engine as may be appropriate.

<FIG> is a fragmentary, isometric view of a disclosed sealing arrangement <NUM> to seal a gap between a first turbine component <NUM>, such as a transition duct exit, and a second turbine component <NUM>, such as a first stage turbine vane structure, in a gas turbine engine. A first arcuate feather seal <NUM> may be connected to an anchoring assembly <NUM> of the sealing arrangement affixed to first turbine component <NUM>. As will be appreciated from disclosure set forth below, anchoring assembly <NUM> may be take any one of various alternative design configurations depending on the needs of a given application.

A second arcuate feather seal <NUM> is affixed to second turbine component <NUM>. Without limitation, first feather seal <NUM> and second feather seal <NUM> are responsive to a pressure differential (schematically represented by arrows <NUM>) that develops across the gap to form a pressure-loaded sealing joint between respective sealing surfaces <NUM>, <NUM> of first arcuate feather seal <NUM> and second arcuate feather seal <NUM>. That is, the pressure differential urges sealing surfaces <NUM>, <NUM> to contactively engage one another to form the pressure-loaded sealing joint and maintain such sealing joint under various thermo-mechanical load scenarios that can routinely develop during operation of the gas turbine engine.

The pressure-loaded sealing joint, which is formed between respective sealing surfaces <NUM>, <NUM> may comprise, without limitation, a radially slidable pressure-loaded sealing joint (e.g., sweeping relative motion) between sealing surfaces <NUM>, <NUM>) to accommodate radial displacements (schematically represented by twin-headed arrow <NUM>) between first turbine component <NUM> and second turbine component <NUM>. The pressure-loaded sealing joint may additionally comprise an axially compliant pressure-loaded sealing joint to accommodate axial displacements (schematically represented by twin-headed arrow <NUM>) between first turbine component <NUM> and second turbine component <NUM>. This feature is effective to accommodate saw-toothing relative motion that commonly develops between adjacent row one vane segments in the gas turbine engine.

As may be appreciated in <FIG>, in one non-limiting embodiment, first arcuate feather seal <NUM> may include a plurality of spaced apart slits <NUM> positioned perpendicular to a longitudinal axis <NUM> of first arcuate feather seal <NUM>. Similarly, second arcuate feather seal <NUM> may include a plurality of spaced apart slits <NUM> positioned perpendicular to a longitudinal axis <NUM> of second arcuate feather seal <NUM>. These features are conducive to improving flexibility of disclosed seal arrangements to better accommodate relative axial and radial motion between the components.

As may be appreciated in <FIG>, arcuate feather seals <NUM>, <NUM> comprise respective multi-ply assemblies joined to form a relatively flexible sealing arrangement effective to reduce leakage rates by ensuring a substantially uniform sealing surface contact under various thermo-mechanical load scenarios. As may be further appreciated in <FIG>, in one non-limiting embodiment, anchoring assembly <NUM> may include an anchor member <NUM> including a radially-extending section <NUM> configured to turn into an axially-extending flange section <NUM>. Anchoring assembly <NUM> may further include a support member <NUM> having a radially outer segment <NUM> having a forward surface <NUM> affixed to a corresponding surface of radially-extending section <NUM> of anchor member <NUM>. Support member <NUM> further includes a radially inner segment <NUM> having an aft surface <NUM> affixed to a corresponding surface of an anchored end segment <NUM> of first arcuate feather seal <NUM>.

In one non-limiting embodiment, the respective sealing surface <NUM> of first arcuate feather seal <NUM> is disposed at a free segment <NUM> of first arcuate feather seal <NUM>. Free segment <NUM> extends away from anchored end segment <NUM> of first arcuate feather seal <NUM>. In one non-limiting embodiment, a respective ply of the respective multi-ply assemblies that respectively defines the sealing surfaces <NUM>, <NUM> may comprise a cloth metal ply.

As may be appreciated in <FIG>, in one non-limiting embodiment, axially-extending flange section <NUM> of anchor member <NUM> may be disposed on a circumferentially-extending step <NUM> constructed at the transition duct exit. In one non-limiting embodiment, the respective sealing surface <NUM> of second arcuate feather seal <NUM> may be disposed at a free end segment <NUM> of second arcuate feather seal <NUM>. Free end segment <NUM> is disposed opposite an anchored end segment <NUM> of second arcuate feather seal <NUM>. Free end segment <NUM> of second arcuate feather seal <NUM> is disposed radially outward relative to anchored end segment <NUM> of the second arcuate feather seal. Anchored end segment <NUM> of second arcuate feather seal <NUM> may be disposed in a circumferentially-extending groove <NUM> constructed at first stage turbine vane structure <NUM>. Without limitation, anchored end segment <NUM> of second arcuate feather seal <NUM> may be retained by an interference fit (schematically represented by dimples <NUM>) or other suitable affixing members, such as affixing pins, etc..

In certain applications, as seen in <FIG>, one may optionally use a retainer block <NUM> to retain anchor assembly <NUM> in step <NUM> at the transition duct exit. Retainer block <NUM> may include a base segment <NUM> positioned against axially-extending flange section <NUM> of anchor member <NUM> to radially retain axially-extending flange section <NUM>. Retainer block <NUM> may further include a radially extending slot <NUM> including a radial end <NUM> positioned to radially retain radially-extending section <NUM> of anchor member <NUM>, and further including a forward surface <NUM> and an aft surface <NUM> to axially retain radially-extending section <NUM> of anchor member <NUM>.

As may be appreciated in <FIG>, in one non-limiting embodiment, a ply of the respective multi-ply assemblies that defines the sealing surfaces <NUM>, <NUM> may comprise a ply coated with a high-temperature abrasion-resistant coating <NUM>, such as, without limitation, a cobalt-based coating, a carbide-based coating or a tungsten-based coating. It will be appreciated that each of the plies that make up first feather seal <NUM> and second feather seal <NUM> may each be respectively coated with high-temperature abrasion-resistant coating <NUM>.

<FIG> is fragmentary, cross-sectional view of an alternative embodiment for affixing a disclosed sealing arrangement to transition duct exit <NUM>. One skilled in the art will appreciate that this an alternative embodiment of anchoring assembly <NUM>. Without limitation, at an outer diameter <NUM>, first arcuate feather seal <NUM> may be joined to a circumferentially-extending lip <NUM> of transition end exit <NUM> by way of a weld joint <NUM>. Without limitation, at an inner diameter <NUM>, first arcuate feather seal <NUM>' may be joined to a lip <NUM>' of transition end exit <NUM> by way of a circumferentially-extending connecting hook <NUM>. One may optionally construct a circumferentially-extending retainer groove <NUM> in a forward surface <NUM> of lip <NUM>' configured to receive a corresponding segment <NUM> of circumferentially-extending connecting hook <NUM>.

<FIG> is fragmentary, cross-sectional view of another alternative embodiment for affixing a disclosed sealing arrangement to transition duct exit. Without limitation, at outer diameter <NUM>, first arcuate feather seal <NUM> may be joined to lip <NUM> of transition end exit <NUM> by way of a bolted joint <NUM>. Without limitation, at inner diameter <NUM>, first arcuate feather seal <NUM>' may be joined to lip <NUM>' of transition end exit <NUM> by way of circumferentially-extending connecting hook. One may optionally dispose a circumferntially-extending L-shaped reinforcer <NUM> including a radially-extending section <NUM> disposed against an aft surface <NUM> of lip <NUM>' of transition end exit <NUM>. L-shaped reinforcer <NUM> may further include an axially-extending section <NUM> disposed against a radially-inner surface <NUM> of lip <NUM>'. In <FIG>, arrows <NUM> and <NUM>' are intended to provide a conceptual visualization of the complex motion (e.g., involving radial and axial motion components) that can be developed at the respective outer and inner diameters of disclosed sealing arrangements.

In operation, disclosed embodiments in a cost-effective and reliable manner, make use of feather seals responsive to a pressure differential that develops across the gap to form a reliable pressure-loaded sealing joint having multiple degrees of freedom, such as can effectively accommodate axial and radial (e.g., saw-toothing) relative motion between adjacent row one vane segments in a gas turbine. Disclosed embodiments are effective to provide low-levels of stress under temperature gradients experienced during operation of the gas turbine engine. Disclosed embodiments are user-friendly for installation during original deployment; or removal and subsequent installation during servicing operations, such as by uncomplicated sliding in or out of the respective turbine components. For example, no need to remove transition ducts during such operations.

Claim 1:
A sealing arrangement (<NUM>) to seal a gap between a first turbine component (<NUM>) and a second turbine component (<NUM>) in a gas turbine engine, the sealing arrangement (<NUM>) comprising:
a first arcuate feather seal (<NUM>) comprising an anchored end segment (<NUM>) and a free end segment (<NUM>), wherein the anchored end segment (<NUM>) of the first arcuate feather seal (<NUM>) is connected to an anchoring assembly (<NUM>) of the sealing arrangement (<NUM>) affixed to the first turbine component (<NUM>); and
a second arcuate feather seal (<NUM>) comprising an anchored end segment (<NUM>) and a free end segment (<NUM>), wherein the anchored end segment (<NUM>) of the second arcuate feather seal (<NUM>) is affixed to the second turbine component (<NUM>), wherein the first arcuate feather seal (<NUM>) and the second arcuate feather seal (<NUM>) are responsive to a pressure differential that develops across the gap to form a pressure-loaded sealing joint between respective sealing surfaces (<NUM>, <NUM>) of the first arcuate feather seal (<NUM>) and the second arcuate feather seal (<NUM>), to contactively engage the first arcuate feather seal and the second arcuate feather seal wherein the respective sealing surface (<NUM>) of the first arcuate feather seal (<NUM>) is disposed at the free end segment (<NUM>) of the first arcuate feather seal (<NUM>), the free end segment (<NUM>) disposed opposite the anchored end segment (<NUM>) of the first arcuate feather seal (<NUM>), and wherein the respective sealing surface (<NUM>) of the second arcuate feather seal (<NUM>) is disposed at the free end segment (<NUM>) of the second arcuate feather seal (<NUM>), the free end segment (<NUM>) disposed opposite the anchored end segment (<NUM>) of the second arcuate feather seal (<NUM>), wherein the free end segment (<NUM>) of the second arcuate feather seal (<NUM>) is disposed radially outward relative to the anchored end segment (<NUM>) of the second arcuate feather seal (<NUM>).