Sealing assembly for use in a rotary machine and methods for assembling a rotary machine

A sealing assembly for use with a rotary machine is described herein. The sealing assembly includes a stator shroud coupled to the casing. The stator shroud includes an inner surface that at least partially defines the cavity within the casing. At least one stator labyrinth tooth extends outwardly from the stator shroud inner surface towards a rotor assembly positioned within the casing. At least one protective member is coupled to the stator shroud upstream from the at least one stator labyrinth tooth to facilitate reducing a flow of combustion gas across the at least one stator labyrinth tooth.

BACKGROUND OF THE INVENTION

The subject matter described herein relates generally to rotary machines and more particularly, to a sealing assembly and methods of assembling a rotary machine.

At least some known turbomachines such as, for example, gas turbine engines include a combustor, a compressor coupled downstream from the combustor, a turbine, and a rotor assembly rotatably coupled between the compressor and the turbine. Some known rotor assemblies include a rotor shaft, at least one rotor disk coupled to the rotor shaft, and a plurality of circumferentially-spaced turbine buckets that extend outwardly from each rotor disk. Each turbine bucket includes an airfoil that extends radially outward from a platform towards a turbine casing.

During operation of at least some known turbines, the compressor compresses air that is subsequently mixed with fuel prior to being channeled to the combustor. The mixture is then ignited to generate hot combustion gases that are channeled to the turbine. The rotating turbine blades or buckets channel high-temperature fluids, such as combustion gases, through the turbine. The turbine extracts energy from the combustion gases for powering the compressor, as well as producing useful work to power a load, such as an electrical generator, or to propel an aircraft in flight.

At least some known turbine engines include a sealing assembly that includes a plurality of stator labyrinth teeth that extend outwardly from a turbine casing towards each turbine bucket to reduce air leakage/air flow between the airfoil and the turbine casing. At least a portion of combustion gases channeled through the turbine are undesirably channeled between a tip end of the turbine bucket and the turbine casing as tip clearance losses. Over time, the labyrinth teeth may begin to oxidize and/or wear as the combustion gases contact the labyrinth teeth, which may increase tip clearance losses and/or reduce an operating efficiency of the turbine.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a sealing assembly for use with a rotary machine is provided. The sealing assembly includes a stator shroud coupled to a casing within the rotary machine. The stator shroud includes an inner surface that at least partially defines a cavity within the casing. At least one stator labyrinth tooth extends outwardly from the stator shroud inner surface towards a rotor assembly positioned within the casing. At least one protective member is coupled to the stator shroud upstream from the at least one stator labyrinth tooth to facilitate reducing a flow of combustion gas across the at least one stator labyrinth tooth.

In another aspect, a rotary machine is provided. The rotary machine includes a sealing assembly oriented between the stator casing and the rotor assembly. The sealing assembly includes a stator shroud that is coupled to the stator casing within the rotary machine. The stator shroud includes an inner surface that at least partially defines the cavity positioned within the casing. At least one stator labyrinth tooth extends outwardly from the stator shroud inner surface towards the rotor assembly and is positioned within the casing. At least one protective member is coupled to the stator shroud upstream from the stator labyrinth tooth to facilitate reducing a flow of combustion gas across the stator labyrinth tooth.

In a further aspect, a method of assembling a rotary machine is provided. The method includes coupling a rotor within the stator casing. A stator shroud is coupled to the stator casing supporting the rotor. The stator shroud includes at least one stator labyrinth tooth that extends outwardly from the stator shroud towards the rotor assembly. At least one protective member is coupled to the stator shroud inner surface upstream from the at least one stator labyrinth tooth to facilitate reducing a flow of combustion gas across the stator labyrinth tooth during rotor operation.

DETAILED DESCRIPTION OF THE INVENTION

The exemplary methods and systems described herein overcome at least some disadvantages of known turbomachines by providing a sealing assembly that includes a protective member that is upstream from a labyrinth tooth to facilitate reducing oxidation of the labyrinth tooth during operation. More specifically, the protective member is positioned adjacent to an upstream surface of the labyrinth tooth to prevent combustion gases from contacting the upstream surface of the tooth. The protective member extends across a full height of the labyrinth tooth such that combustion gases are substantially prevented from contacting the labyrinth tooth to facilitate reducing an oxidation of the labyrinth tooth.

As used herein, the term “upstream” refers to a forward or inlet end of a rotary machine, and the term “downstream” refers to an aft or discharge end of the rotary machine.

FIG. 1is a schematic view of an exemplary turbine engine system10. In the exemplary embodiment, turbine engine system10includes an intake section12, a compressor section14that is downstream from intake section12, a combustor section16that is downstream from compressor section14, a turbine section18that is downstream from combustor section16, and an exhaust section20that is downstream from turbine section18. Turbine section18is coupled to compressor section14via a rotor assembly22. Rotor assembly22includes a rotor shaft24that extends along a centerline axis26, and is coupled to turbine section18and compressor section14. In the exemplary embodiment, combustor section16includes a plurality of combustors28. Combustor section16is coupled to compressor section14such that each combustor28is in flow communication with compressor section14. Combustor section16is also coupled to turbine section18for channeling a working fluid towards turbine section18. Turbine section18is also coupled to a load30such as, but not limited to, an electrical generator and/or a mechanical drive application.

During operation, intake section12channels air towards compressor section14wherein the air is compressed to a higher pressure and temperature prior to being discharged towards combustor section16. Combustor section16mixes the compressed air with fuel, ignites the fuel-air mixture to generate a working fluid such as, for example, combustion gases, and channels the combustion gases towards turbine section18. More specifically, in each combustor28, fuel, for example, natural gas and/or fuel oil, is injected into the air flow, and the fuel-air mixture is ignited to generate high temperature combustion gases that are channeled towards turbine section18. Turbine section18converts thermal energy from the gas stream to mechanical rotational energy as the combustion gases impart rotational energy to turbine section18and to rotor assembly22.

FIG. 2is a partial sectional view of a portion of rotor assembly22.FIG. 3is an enlarged partial sectional view of a portion of rotor assembly22taken along area3. In the exemplary embodiment, turbine section18includes a stator casing32that includes a fluid inlet34, a fluid outlet36, and an inner surface38that defines a cavity40that extends between fluid inlet34and fluid outlet36. Rotor assembly22is positioned within stator casing32such that a combustion gas path, represented by arrow42, is defined between casing inner surface38and rotor assembly22. Rotor assembly22includes a plurality of turbine bucket assemblies44that are coupled to rotor shaft24, and that extend between fluid inlet34and fluid outlet36. Each turbine bucket assembly44includes a plurality of turbine buckets46that extend radially outwardly from a rotor disk48. Each rotor disk48is coupled to rotor shaft24, and rotates about centerline axis26. In the exemplary embodiment, each turbine bucket46is coupled to an outer surface50of rotor disk48, and is spaced circumferentially about rotor disk48such that combustion gas path42is defined between stator casing32and each rotor disk48. Each turbine bucket46extends at least partially through a portion of combustion gas path42, and includes an airfoil52that extends radially outwardly from rotor disk48towards casing inner surface38. Airfoil52extends between a root end54and a tip end56. Root end54is coupled to rotor disk48. Tip end56extends outwardly from root end54towards stator casing32. Turbine section18also includes a plurality of stator vane assemblies57that are coupled to casing32and extend circumferentially about rotor shaft24. Each stator vane assembly57is oriented between adjacent turbine bucket assemblies44for channeling combustion gases downstream towards a corresponding turbine bucket assembly44.

In the exemplary embodiment, turbine section18includes a plurality of sealing assemblies58that are each oriented between a turbine bucket46and stator casing32such that a tortuous path, represented by arrow60, is formed between stator casing32and turbine bucket tip end56to facilitate reducing working fluid leakage, represented by arrow61, between stator casing32and turbine bucket46. Sealing assembly58extends circumferentially about rotor assembly22, and includes a tip shroud62, and a stator shroud64that is oriented with respect to tip shroud62such that tortuous path60is defined between stator shroud64and tip shroud62. Tip shroud62is coupled to turbine bucket tip end56and extends radially outwardly from turbine bucket46towards stator casing32. Tip shroud62includes at least one rotor labyrinth tooth66that extends outwardly from turbine bucket46towards stator casing32. Each rotor labyrinth tooth66extends at least partially through a portion of tortuous path60. In the exemplary embodiment, tip shroud62includes a pair68of axially-spaced rotor labyrinth teeth66.

Stator shroud64is coupled to casing inner surface38and extends radially inwardly from stator casing32towards rotor assembly22such that stator shroud64is oriented circumferentially about rotor assembly22. Stator shroud64extends between a radially outer surface70and a radially inner surface72. Stator casing32includes a projection74that extends outwardly from casing inner surface38. Projection74extends between an upstream surface76and a downstream surface78along centerline axis26, and is oriented circumferentially about rotor assembly22. Stator shroud64includes a dovetail groove80that is defined within stator shroud outer surface70, and is sized and shaped to receive casing projection74therein to couple stator shroud64to stator casing32.

Stator shroud groove80is defined by an interior surface82that extends between a first axial inner surface84and a second axial inner surface86along centerline axis26. First and second axial surfaces84and86extend radially inwardly from shroud outer surface70to interior surface82. In the exemplary embodiment, stator shroud64includes a first bearing hook88and a second bearing hook90. Each bearing hook88and90facilitates preventing stator shroud64from moving radially outwardly with respect to stator casing32. More specifically, first bearing hook88extends outwardly from first axial inner surface84towards upstream surface76, and second bearing hook90extends outwardly from second axial inner surface86towards downstream surface78. Projection74includes a pair of bearing flanges92that extend outwardly from upstream surface76and downstream surface78, respectively. Each bearing flange92is oriented to engage respective bearing hooks88and90to facilitate securely coupling stator shroud64to stator casing32.

In the exemplary embodiment, sealing assembly58also includes at least one stator labyrinth tooth94, and at least one protective member96that is positioned adjacent to stator labyrinth tooth94. Stator labyrinth tooth94and protective member96each extend circumferentially about rotor assembly22, and each extend outwardly from stator shroud inner surface72towards the rotor assembly22. Stator labyrinth tooth94extends at least partially through a portion of tortuous path60, and is oriented between adjacent rotor labyrinth teeth66. Stator labyrinth tooth94includes a base end98, a tip end100, an upstream surface102, and a downstream surface104. Each upstream surface102and downstream surface104extends between base end98and tip end100. Downstream surface104is axially-spaced from upstream surface102along centerline axis26. Base end98is oriented adjacent to stator shroud inner surface72. Tip end100extends outwardly from base end98towards rotor assembly22along a radial axis106such that stator labyrinth tooth94includes a height108measured between base end98and tip end100. In the exemplary embodiment, stator labyrinth tooth94is formed unitarily with stator shroud64. Alternatively, stator labyrinth tooth94may be coupled to stator shroud64.

Protective member96is coupled to stator shroud64, and is upstream from stator labyrinth tooth94to facilitate reducing a flow of combustion gas across stator labyrinth tooth94. In the exemplary embodiment, protective member96includes a base portion110, a tip portion112, an upstream side surface114, and a downstream side surface116. Base portion110and tip portion112each extend between upstream side surface114and downstream side surface116along centerline axis26such that protective member96includes a width118measured between upstream side surface114and downstream side surface116. Base portion110is coupled to stator shroud inner surface72. Tip portion112extends outwardly from base portion110towards rotor assembly22such that protective member96has a height120measured between base portion110and tip portion112along radial axis106. Side surfaces114and116each extend between base portion110and tip portion112. Upstream side surface114includes a first height122measured between base portion110and tip portion112along radial axis106, and downstream side surface116includes a second height124measured between base portion110and tip portion112. In the exemplary embodiment, upstream side surface height122is greater than downstream side surface height124. Alternatively, upstream side surface height122may be shorter than, or approximately equal to downstream side surface height124.

Protective member96is oriented with respect to stator labyrinth tooth94such that protective member96is adjacent to stator labyrinth tooth upstream surface102. More specifically, protective member96is oriented such that protective member downstream side surface116is adjacent to stator labyrinth tooth upstream surface102such that downstream side surface116extends across upstream surface102to facilitate preventing combustion gases61from contacting upstream surface102. In the exemplary embodiment, downstream side surface height124is approximately equal to stator labyrinth tooth height108such that downstream side surface116extends across a full height108of stator labyrinth tooth94. Alternatively, downstream side surface height124may be shorter than, taller than, or greater than stator labyrinth tooth height108. In an alternative embodiment, protective member96may extend across stator labyrinth tooth94such that stator labyrinth tooth94is encapsulated within protective member96.

In the exemplary embodiment, protective member tip portion112includes a tip surface126that extends between upstream side surface114and downstream side surface116. Protective member96includes a groove128that is defined within tip surface126, and that extends circumferentially about rotor assembly22. Groove128is sized and shaped to receive at least a portion of rotor labyrinth tooth66therein. More specifically, protective member96is oriented with respect to rotor labyrinth tooth66such that a tip end130of rotor labyrinth tooth66is oriented within at least a portion of groove128. In one embodiment, protective member96is a honeycombed material. In the exemplary embodiment, protective member96includes a layer132of abradable material such as, for example a honeycombed material. Abradable layer132is oriented adjacent to rotor labyrinth tooth66such that rotor labyrinth tooth tip end130contacts at least a portion of abradable layer132such that a portion of abradable layer132is removed during rotation of rotor assembly22to form groove128as turbine bucket46thermally expands.

In the exemplary embodiment, stator labyrinth tooth94includes a first substrate material134, and protective member96includes a second substrate material136that is different than first substrate material134. More specifically, protective member substrate material136has an oxidation resistance that is greater than an oxidation resistance of stator tooth substrate material134such that, during operation, stator labyrinth tooth94oxidizes at a rate that is greater than an oxidation rate of protective member96. In addition, protective member substrate material136includes a temperature resistance that is greater than a temperature resistance of stator tooth substrate material134. By orienting protective member96upstream of stator labyrinth tooth94, such that a portion of protective member96is between stator labyrinth tooth94and combustion gases, oxidation of stator labyrinth tooth94is facilitated to be reduced because contact between combustion gases61and stator labyrinth tooth94is reduced.

FIGS. 4 and 5are enlarged partial sectional views of alternative embodiments of sealing assembly58. Identical components shown inFIGS. 4 and 5are labeled with the same reference numbers used inFIG. 3. In an alternative embodiment, sealing assembly58includes a plurality of stator labyrinth teeth94that each extend outwardly from stator shroud inner surface72, and a plurality of protective members96that are each coupled to stator shroud64. Each protective member96is upstream from a corresponding stator labyrinth tooth94to prevent combustion gases61from contacting each stator labyrinth tooth94. Referring toFIG. 4, in one embodiment, sealing assembly58includes a first stator labyrinth tooth138and a second stator labyrinth tooth140oriented downstream from first stator labyrinth tooth138. First stator labyrinth tooth138is oriented between adjacent rotor labyrinth teeth66. Second stator labyrinth tooth140is downstream from rotor labyrinth teeth66and is axially-spaced a distance142from first stator labyrinth tooth138such that a first gap144is defined between first and second stator labyrinth teeth138and140.

Sealing assembly58also includes a first protective member146and a second protective member148. First protective member146is upstream from first stator labyrinth tooth138, and is positioned adjacent to first stator labyrinth tooth138to prevent combustion gases61from contacting an upstream surface150of first stator labyrinth tooth138. Second protective member148is between first stator labyrinth tooth138and second stator labyrinth tooth140, and is positioned adjacent to second stator labyrinth tooth140to prevent combustion gases61from contacting an upstream surface152of second stator labyrinth tooth140. Second protective member148has a width154measured between an upstream side surface156and a downstream side surface158that is approximately equal to distance142such that second protective member148extends across first gap144. First and second protective members146and148each include a groove160that is sized and shaped to receive a corresponding rotor labyrinth tooth66therein.

Referring toFIG. 5, in one embodiment, sealing assembly58includes a third stator labyrinth tooth162and a third protective member164. Third stator labyrinth tooth162is upstream from first stator labyrinth tooth138, and is spaced a distance166upstream from first stator labyrinth tooth138such that a second gap168is defined between first stator labyrinth tooth138and third stator labyrinth tooth162. Third stator labyrinth tooth162is also upstream from rotor labyrinth teeth66. In the exemplary embodiment, first protective member146extends between first stator labyrinth tooth138and third stator labyrinth tooth162, and has a width170measured between an upstream side surface172and a downstream side surface174that is approximately equal to distance166. As such, first protective member146extends across second gap168such that upstream side surface172is adjacent to a downstream surface176of third stator labyrinth tooth162. Third protective member164is upstream from third stator labyrinth tooth162, and is positioned adjacent to an upstream surface178of third stator labyrinth tooth162to facilitate preventing combustion gases61from contacting third stator tooth upstream surface178.

The size, shape, and orientation of protective member96is selected to facilitate reducing an oxidation of stator labyrinth tooth94during operation of turbine engine10. Moreover, the size, shape, and orientation of protective member96is selected to reduce direct contact between combustion gases and stator tooth upstream surface102. By reducing direct contact between combustion gases and stator labyrinth tooth94, an oxidation and wear of stator labyrinth tooth94is reduced, such that the useful life of sealing assembly58is increased.

The above-described sealing assembly overcomes at least some disadvantages of known turbomachines by providing a sealing assembly that includes a protective member that is upstream from a labyrinth tooth to facilitate reducing oxidation of the labyrinth tooth during operation. More specifically, the sealing assembly includes a protective member that is adjacent to an upstream surface of the labyrinth tooth to prevent combustion gases from contacting the upstream surface. By providing a protective member that extends across a full height of the labyrinth tooth, combustion gases are prevented from contacting the labyrinth tooth and oxidation of the labyrinth tooth is reduced. As such, losses in gas energy are reduced and the useful life of the turbine engine is increased.

Exemplary embodiments of a sealing assembly for use with rotary machines and methods of assembling a rotary machine are described above in detail. The sealing assemblies described herein are not limited to the specific embodiments described herein, but rather, components of the sealing assemblies may be utilized independently and separately from other components described herein. For example, the sealing assemblies may be used in combination with other rotary machines, and are not limited to being used with only the rotary machine and operations thereof, as described herein. Rather, the sealing assembly can be implemented and utilized in connection with many other sealing applications.

Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. Moreover, references to “one embodiment” in the above description are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.