Hydrostatic non-contact seal with offset outer ring

A non-contact seal assembly includes a plurality of seal shoes arranged about a centerline in an annular array, the seal shoes including a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. The non-contact seal assembly may comprise a seal base circumscribing axially offset from the annular array of the seal shoes. The non-contact seal assembly may further comprise a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes, and each of the plurality of spring elements is axially adjacent to the seal base.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates generally to hydrostatic non-contact seals. More particularly, the disclosure relates to hydrostatic non-contact seals that use an offset outer ring.

2. Background Information

Rotational equipment typically includes one or more seal assemblies for sealing gaps between rotors and stators. A typical seal assembly includes a contact seal with a seal element such as a knife edge seal that engages a seal land. The hydrostatic non-contact seal includes a full ring portion that connects beams and shoes together, in order to function properly as a full seal ring. The full ring is located outboard of the beams and the shoes. This adds radial weight to the seal assembly. It is typical to be radially challenged for space in a gas turbine engine which may require parts to be thinned or reconfigured to fit and function properly in the design space.

It would be desirable to reduce the radial height and/or the weight of the seal.

SUMMARY OF THE DISCLOSURE

Aspects of the disclosure are directed to a non-contact seal assembly, having a plurality of seal shoes arranged about a centerline in an annular array, the seal shoes including a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. The non-contact seal assembly may comprise a seal base circumscribing axially offset from the annular array of the seal shoes. The non-contact seal assembly may further comprise a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes, and each of the plurality of spring elements is axially adjacent to the seal base.

The seal base may be connected to a seal carrier surface that is substantially cylindrical and extends circumferentially around and faces towards the centerline.

The non-contact seal assembly may further comprise a first ring structure configured and arranged to at least one of position, support or mount to a secondary seal device axially separated from the seal base and radially adjacent to the first seal shoe

The non-contact seal assembly may further comprise a secondary seal device axially and radially adjacent to the seal base and axially adjacent to first the seal shoe.

The seal assembly may comprise nickel alloy.

The seal assembly may comprise one of cobalt alloy or aluminum.

The first seal shoe may extend circumferentially, at the first shoe end, between a first shoe side and a second shoe side for a seal shoe length.

The seal shoes may collectively form a substantially annular end surface at the second shoe end.

According to another aspect of the present disclosure, a non-contact seal is provided. The non-contact seal assembly may provide a plurality of seal shoes arranged about a centerline in an annular array, the seal shoes including a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. The non-contact seal assembly may comprise a seal base circumscribing axially offset along the centerline from the annular array of the seal shoes. The non-contact seal assembly may further comprise a plurality of spring elements, each of the spring elements radially between and connecting a respective one of the seal shoes with the seal base. The non-contact seal assembly may further comprise a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes, and each of the plurality of spring elements is axially adjacent to the seal base, where a void is formed by a most radially distal one of the plurality of spring elements, the axially offset seal base, a stator structure, and a ring structure that is axially separated from the axially offset seal base by the plurality of spring elements.

The axially offset seal base may be connected to a seal carrier surface that is substantially cylindrical and extends circumferentially around and faces toward the centerline.

The non-contact seal assembly may further comprise a first ring structure configured and arranged to at least one position, support or mount to a secondary seal device axially separated from the axially offset seal base and radially adjacent to the first seal shoe.

The non-contact seal assembly may further comprise a secondary seal device that is axially and radially adjacent to the axially offset seal base and axially adjacent to the first seal shoe.

The seal assembly may comprise nickel alloy.

The seal assembly may comprise one of cobalt alloy or aluminum.

The first seal shoe extends circumferentially, at the first shoe end, between a first shoe side and a second shoe side for a seal shoe length.

According to another aspect of the present disclosure, an assembly for rotational equipment with an axial centerline is provided. The assembly may comprise a stator structure and a rotor structure. The assembly may comprise a seal assembly configured to substantially seal an annular gap between the stator structure and the rotor structure, the seal assembly comprising a hydrostatic non-contact seal device including a plurality of seal shoes, an axially offset seal base and a plurality of spring elements. The seal shoes arranged about a centerline in an annular array, the seal shoes sealingly engaging the rotor structure and including a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. The axially offset seal base circumscribing the annular array of the seal shoes, the axially offset seal base mounted with the stator structure. The assembly may comprise a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes, and each of the plurality of spring elements is axially adjacent to the axially offset seal base, where the axially offset seal base is axially offset with respect to the plurality of spring elements.

The axially offset seal base may be connected to a seal carrier surface that is substantially cylindrical and extends circumferentially around and faces towards the centerline.

The assembly for rotational equipment may further comprise a first ring structure configured and arranged to at least one of position, support or mount to a secondary seal device axially separated from the axially offset seal base and radially adjacent to the first seal shoe.

The assembly for rotational equipment may further comprise a secondary seal device that is axially and radially adjacent to the axially offset seal base and axially adjacent to the first seal shoe.

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are incorporated in this specification by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities or a space/gap between the entities that are being coupled to one another.

Aspects of the disclosure may be applied in connection with a gas turbine engine.

FIG. 1illustrates an assembly20for rotational equipment with an axial centerline22. An example of such rotational equipment is a gas turbine engine for an aircraft propulsion system, an exemplary embodiment of which is described below in further detail. However, the assembly20of the present disclosure is not limited to such an aircraft or gas turbine engine application. The assembly20, for example, may alternatively be configured with rotational equipment such as an industrial gas turbine engine, a wind turbine, a water turbine, or any other apparatus in which a seal is provided between a stator structure and a rotor structure.

The assembly20ofFIG. 1includes a stator structure24, a rotor structure26and a seal assembly28. This seal assembly28is mounted with the stator structure24, and configured to substantially seal an annular gap30between the stator structure24and the rotor structure26as described below in further detail.

The stator structure24includes a seal carrier32. This seal carrier32may be a discrete, unitary annular body. Alternatively, the seal carrier32may be configured with another component/portion of the stator structure24. The seal carrier32has an inner radial seal carrier surface34. This seal carrier surface34may be substantially cylindrical, and extends circumferentially around and faces towards the axial centerline22. The seal carrier surface34at least partially forms a bore in the stator structure24. This bore is sized to receive the seal assembly28, which may be fixedly attached to the seal carrier32by, for example, a press fit connection between the seal assembly28and the seal carrier surface34.

The rotor structure26includes a seal land36. This seal land36may be a discrete, unitary annular body. Alternatively, the seal land36may be configured with another component/portion of the rotor structure26. The seal land36has an outer radial seal land surface38. This seal land surface38may be substantially cylindrical, and extends circumferentially around and faces away from the axial centerline22. The seal land surface38is disposed to face towards and is axially aligned with the seal carrier surface34. WhileFIG. 1illustrates the surfaces34and38with approximately equal axial lengths along the axial centerline22, the seal land surface38may alternatively be longer or shorter than the seal carrier surface34in other embodiments.

The seal assembly28includes a primary seal device40and one or more secondary seal devices42; e.g., 1, 2, 3 or more secondary seal devices42. The seal assembly28also includes one or more additional components for positioning, supporting and/or mounting one or more of the seal devices40and42with the stator structure24. The seal assembly28ofFIG. 1, for example, includes a first ring structure44configured for positioning, supporting and/or mounting the secondary seal devices42relative to the primary seal device40. This first ring structure44may also be configured for axially positioning and/or supporting a second end surface46of the primary seal device40relative to the stator structure24. The seal assembly28ofFIG. 1also includes a second ring structure48(e.g., a scalloped support ring) configured for axially positioning and/or supporting a first end surface50of the primary seal device40relative to the stator structure24. However, the second ring structure48may be omitted where, for example, the first end surface50of the primary seal device40may be abutted against another component/portion of the stator structure24(e.g., an annular or castellated shoulder) or otherwise axially positioned/secure with the stator structure24.

The primary seal device40may be configured as an annular non-contact seal device and, more particularly, a hydrostatic non-contact seal device. An example of such a hydrostatic non-contact seal device is a Hydrostatic Adaptive Low Leakage (“HALO™)” seal; however, the primary seal device40of the present disclosure is not limited to the foregoing exemplary hydrostatic non-contact seal device.

The primary seal device40includes a plurality of seal shoes54, a plurality of spring elements56and a seal base/outer ring52that is axially (referring to axial centerline22) offset from the spring elements56. The seal shoes54are configured as arcuate bodies arranged circumferentially about the axial centerline22in an annular array. This annular array of the seal shoes54extends circumferentially around the axial centerline22, thereby forming an inner bore at an inner radial side62of the primary seal device40. The inner bore is sized to receive the seal land36, where the rotor structure26projects axially through (or into) the inner bore formed by the seal shoes54.

Referring toFIGS. 1-3, each of the seal shoes54extends radially from the inner radial side62of the primary seal device40to an outer radial surface64of that seal shoe54. Each of the seal shoes54extends circumferentially around the axial centerline22between opposing first and second circumferential sides66and68of that seal shoe54.

Referring toFIG. 1, each of the seal shoes54extends axially along the axial centerline22between a first shoe end70and a second shoe end72. The first shoe end70may be axially offset from and project axially away from the first end surface50. The second shoe end72may be axially offset from and project axially away from the second end surface46. The seal shoes54of the present disclosure, however, are not limited to such exemplary relationships.

Each of the seal shoes54may include an arcuate end surface74generally at (e.g., on, adjacent or proximate) the second shoe end72. In the array (seeFIG. 2), these arcuate end surfaces74collectively form a generally annular (but circumferentially segmented) end surface76configured for sealingly engaging with the secondary seal devices42; seeFIG. 1. The seal shoes54of the present disclosure, however, are not limited to the foregoing exemplary configuration.

Each of the seal shoes54includes one or more arcuate protrusions78, which collectively form one or more (e.g., a plurality) of axially spaced generally annular (e.g., circumferentially segmented) ribs.80at the inner radial side62. Distal inner radial ends82of one or more of these ribs80are configured to be arranged in close proximity with (but not touch) and thereby sealingly engage the seal land surface38in a non-contact manner (seeFIG. 1), where the rotor structure26project axially through (or into) the inner bore formed by the seal shoes54. The ribs80therefore are configured, generally speaking, as non-contact knife edge seal elements.

Referring toFIGS. 1-3, the spring elements56are arranged circumferentially about the axial centerline22in an annular array. The spring elements56are also arranged radially between the seal shoes54and the seal base52. The spring element56, for example, includes one or more mounts83and84(e.g., generally radial fingers/projections) and one or more beams86(e.g., cantilever-leaf springs). The first mount83is connected to a respective one of the seal shoes54at (e.g., on, adjacent or proximate) the first circumferential side68, where the opposing second circumferential side66of that seal shoe54is free floating. The second mount84is connected to an offset seal base/outer ring52, and is generally circumferentially aligned with or near the second circumferential side68. With respect to the axial center line22, the offset seal base52is axially offset with respect to the radially most distal beam86, such that the offset seal base52does not radially cover the radially most distal beam86. The beams are radially stacked and spaced apart with one another. Each of these beams86extends laterally (e.g., tangentially or circumferentially) from the first mount83to the second mount84. These spring elements56may thereby laterally overlap a major circumferential portion (e.g., ˜50-100%) of the seal shoe54. In contrast, the offset seal base52does not laterally overlap at least a primary circumferential portion (e.g., ˜65-100%) of the radially most distal beam86. Subsequently, the radial height of seal assembly28may be substantially reduced, to increase radial space and improve packaging with adjacent hardware.FIGS. 1-3illustrate an embodiment in which the offset seal base/outer ring does not overlap any portion of the radially most distal of the beams86. The spring elements56of the present disclosure, however, are not limited to the foregoing exemplary configuration or values.

During operation of the primary seal device40, rotation of the rotor structure26may develop aerodynamic forces and apply a fluid pressure to the seal shoes54causing the each seal shoe54to respectively move radially relative to the seal land surface38. The fluid velocity may increase as a gap between the seal shoe54and seal land surface38increases, thus reducing pressure in the gap and drawing the seal shoe54radially inwardly toward the seal land surface38. As the gap closes, the velocity may decrease and the pressure may increase within the gap, thus, forcing the seal shoe54radially outward from the seal land surface38. The respective spring element56may deflect and move with the seal shoe54to create a primary seal of the gap between the seal land surface38and ribs80within predetermined design tolerances.

Referring again toFIG. 1, while the primary seal device40is operable to generally seal the annular gap30between the stator structure24and the rotor structure26as described above, fluid (e.g., gas) may still flow axially through passages96defined by radial gaps between the components.52,54and56. The secondary seal devices42therefore are provided to seal off these passages96and, thereby, further and more completely seal the annular gap30.

Each of the secondary seal devices42may be configured as a ring seal element such as, but not limited to, a split ring. Alternatively, one or more of the secondary seal devices42may be configured as a full hoop body ring, an annular brush seal or any other suitable ring-type seal.

As described above, the assembly20of the present disclosure may be configured with various different types and configurations of rotational equipment.FIG. 4illustrates one such type and configuration of the rotational equipment—a geared turbofan gas turbine engine106. Such a turbine engine106includes various stator structures (e.g., bearing supports, hubs, cases, etc.) as well as various rotor structures (e.g., rotor disks, shafts, etc.) as described below, where the stator structure24and the rotor structure26can respectively be configured as anyone of the foregoing structures in the turbine engine106ofFIG. 4, or other structures not mentioned herein. Referring again toFIG. 1, while the primary seal device40is operable to generally seal the annular gap30between the stator structure24and the rotor structure26as described above, fluid (e.g., gas) may still flow axially through passages96defined by radial gaps between the components52,54and56. The secondary seal devices42therefore are provided to seal off these passages96and, thereby, further and more completely seal the annular gap30.

The secondary seal devices42ofFIG. 1are arranged together in an axial stack. In this stack, each of the secondary seal devices42axially engages (e.g., contacts) another adjacent one of the secondary seal devices42. The stack of the secondary seal devices42is arranged with the first ring structure44, which positions and mounts the secondary seal devices42with the stator structure24adjacent the primary seal device40. In this arrangement, the stack of the secondary seal devices42is operable to axially engage and form a seal between the end surface76of the array of the seal shoes54and an annular surface98of the first ring structure44. These surfaces76and98are axially aligned with one another, which enables the stack of the secondary seal devices42to slide radially against, but maintain sealing engagement with, the end surface76as the seal shoes54move radially relative to the seal land surface38as described above.

The first ring structure44may include a secondary seal device support ring100and a retention ring102. The support ring100is configured with an annular full hoop body, which extends circumferentially around the axially centerline22. The support ring100includes the annular surface98, and is disposed axially adjacent and engaged with the seal base52.

The retention ring102is configured with an annular full hoop body, which extends circumferentially around the axially centerline22. The retention ring102is disposed axially adjacent and engaged with the support ring100, thereby capturing the stack of the secondary seal devices42within an annular channel formed between the rings100and102. The stack of the secondary seal devices42may also or alternatively be attached to one of the rings100and102by, for example, a press fit connection and/or otherwise.

Referring still toFIG. 4, the turbine engine106extends along an axial centerline108(e.g., the centerline22) between an upstream airflow inlet110and a downstream airflow exhaust112. The turbine engine106includes a fan section114, a compressor section115, a combustor section116and a turbine section117. The compressor section115includes a low pressure compressor (LPC) section115A and a high pressure compressor (HPC) section115B. The turbine section117includes a high pressure turbine (HPT) section117A and a low pressure turbine (LPT) section117B.

The engine sections114-117are arranged sequentially along the centerline108within an engine housing118, a portion or component of which may include or be connected to the stator structure24. This housing118includes an inner case120(e.g., a core case) and an outer case122(e.g., a fan case). The inner case120may house one or more of the engine sections; e.g., an engine core. The outer case122may house at least the fan section114.

Each of the engine sections114,115A,115B,117A and117B includes a respective rotor124-128. Each of these rotors124-128includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s).

The fan rotor124is connected to a gear train130, for example, through a fan shaft132. The gear train130and the LPC rotor125are connected to and driven by the LPT rotor128through a low speed shaft133. The HPC rotor126is connected to and driven by the HPT rotor127through a high speed shaft134. The shafts132-134are rotatably supported by a plurality of bearings136; e.g., rolling element and/or thrust bearings. Each of these bearings136is connected to the engine housing118by at least one stationary structure such as, for example, an annular support strut.

During operation, air enters the turbine engine106through the airflow inlet110. This air is directed through the fan section114and into a core gas path138and a bypass gas path140. The core gas path138flows sequentially through the engine sections115-117. The bypass gas path140flows away from the fan section114through a bypass duct, which circumscribes and bypasses the engine core. The air within the core gas path138may be referred to as “core air”. The air within the bypass gas path140may be referred to as “bypass air”.

The core air is compressed by the compressor rotors125and126and directed into a combustion chamber142of a combustor in the combustor section116. Fuel is injected into the combustion chamber142and mixed with the compressed core air to provide a fuel-air mixture. This fuel air mixture is ignited and combustion products thereof flow through and sequentially cause the turbine rotors127and128to rotate. The rotation of the turbine rotors127and128respectively drive rotation of the compressor rotors126and125and, thus, compression of the air received from a core airflow inlet. The rotation of the turbine rotor128also drives rotation of the fan rotor124, which propels bypass air through and out of the bypass gas path140. The propulsion of the bypass air may account for a majority of thrust generated by the turbine engine106, e.g., more than seventy-five percent (75%) of engine thrust. The turbine engine106of the present disclosure, however, is not limited to the foregoing exemplary thrust ratio.

The assembly20may be included in various aircraft and industrial turbine engines other than the one described above as well as in other types of rotational equipment; e.g., wind turbines, water turbines, rotary engines, etc. The assembly20, for example, may be included in a geared turbine engine where a gear train connects one or more shafts to one or more rotors in a fan section, a compressor section and/or any other engine section. Alternatively, the assembly20may be included in a turbine engine configured without a gear train. The assembly20may be included in a geared or non-geared turbine engine configured with a single spool, with two spools (e.g., seeFIG. 5), or with more than two spools. The turbine engine may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine or any other type of turbine engine. The present invention therefore is not limited to any particular types or configurations of turbine engines or rotational equipment.