US20210131288A1

Movatterモバイル変換

Info

Publication number: US20210131288A1
Application number: US16/674,238
Authority: US
Inventors: Peter Karkos
Original assignee: Raytheon Technologies Corp
Current assignee: RTX Corp
Priority date: 2019-11-05
Filing date: 2019-11-05
Publication date: 2021-05-06
Also published as: EP3819467A1; US11015451B1; EP3819467B1

Abstract

Blade assemblies for gas turbine engines are described. The blade assemblies include a fan blade having a first tab extending from a leading edge and a second tab extending from a trailing edge. A first platform is affixed to a first side of the fan blade at the first and second tabs and a second platform is affixed to a second side of the fan blade at the first and second tabs. At least one first fastener is arranged to connect the first platform, the first tab, and the second platform at a first end and at least one second fastener is arranged to connect the first platform, the second tab, and the second platform at a second end.

Description

BACKGROUND

The subject matter disclosed herein generally relates to airfoil platforms used in gas turbine engines and, more particularly, to airfoil-mounted platforms.

Gas turbine engines generally include a fan section, a compressor second, a combustor section, and turbine sections positioned along a centerline referred to as an “axis of rotation.” The fan, compressor, and combustor sections add work to air (also referred to as “core gas”) flowing through the engine. The turbine extracts work from the core gas flow to drive the fan and compressor sections. The fan, compressor, and turbine sections each include a series of stator and rotor assemblies. The stator assemblies, which do not rotate (but may have variable pitch vanes), increase the efficiency of the engine by guiding core gas flow into or out of the rotor assemblies.

The fan section includes a rotor assembly and a stator assembly. The rotor assembly of the fan includes a hub and a plurality of outwardly extending rotor blades. Each rotor blade includes an airfoil portion, a dove-tailed root portion, and a platform. The airfoil portion extends through the flow path and interacts with the working medium gases to transfer energy between the rotor blade and working medium gases. The dove-tailed root portion engages attachment means of the hub. The platform typically extends circumferentially from the rotor blade to a platform of an adjacent rotor blade. The platform is disposed radially between the airfoil portion and the root portion. The stator assembly includes a fan case, which circumscribes the rotor assembly in close proximity to the tips of the rotor blades.

To reduce the size and cost of the rotor blades, the platform size may be reduced and a separate fan blade platform may be attached to the hub. To accommodate the separate fan blade platforms, outwardly extending tabs or lugs may be forged onto the hub to enable attachment of the platforms. Improved rotor systems and/or platforms may be advantageous.

SUMMARY

According to some embodiments, blade assemblies for gas turbine engines are provided. The blade assemblies include a fan blade having a leading edge, a trailing edge, a root, a tip, a first side, and a second side, the fan blade having a first tab extending from the leading edge proximate the root and a second tab extending from the trailing edge proximate the root. A first platform is affixed to the first side of the fan blade at the first tab and the second tab and extends in a direction from the leading edge to the trailing edge along the first side. A second platform is affixed to the second side of the fan blade at the first tab and the second tab and extends in a direction from the leading edge to the trailing edge along the first side. At least one first fastener connects the first platform, the first tab, and the second platform and at least one second fastener connecting the first platform, the second tab, and the second platform.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that the fan blade defines a mounting region extending from the first tab to the second tab on each of the first side and the second side.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that a friction retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that a bonding retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that the bonding interface includes an epoxy to bond a material of the first platform member to the first side of the fan blade.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that the mounting region of the fan blade comprises a smooth surface.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that the mounting region of the fan blade comprises at least one rib configured to engage with a contact surface of the first platform member.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that at least one of (i) the first platform member defines a geometry different than a geometry of the first side of the fan blade such that a pre-load is defined by the first platform member and (ii) the second platform member defines a geometry different than a geometry of the second side of the fan blade such that a pre-load is defined by the second platform member.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include a stiffening rib attached to the first platform member.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that the at least one first fastener is at least one of a bolt, a snap bolt, a preload washer, and a crimped metal band.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include that an end of the first platform member proximate the first tab includes a retention snap end configured to engage with an end of the second platform member proximate the first tab such that the first tab is disposed between the end of the first platform member and the end of the second platform member.

In addition to one or more of the features described above, or as an alternative, further embodiments of the blade assemblies may include a seal attached to at least one of the first platform member and the second platform member.

According to some embodiments, gas turbine engines are provided. The gas turbine engines include a hub and a blade assembly mounted to the hub. The blade assembly includes a fan blade having a leading edge, a trailing edge, a root, a tip, a first side, and a second side, the fan blade having a first tab extending from the leading edge proximate the root and a second tab extending from the trailing edge proximate the root. A first platform is affixed to the first side of the fan blade at the first tab and the second tab and extends in a direction from the leading edge to the trailing edge along the first side. A second platform is affixed to the second side of the fan blade at the first tab and the second tab and extends in a direction from the leading edge to the trailing edge along the first side. At least one first fastener connects the first platform, the first tab, and the second platform and at least one second fastener connects the first platform, the second tab, and the second platform.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include a plurality of additional blade assemblies distributed about a circumference of the hub.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include a seal attached to at least one of the first platform member and the second platform member, wherein the seal provides a seal between the blade assembly and an adjacent one of the plurality of additional blade assemblies.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include that the fan blade defines a mounting region extending from the first tab to the second tab on each of the first side and the second side.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include that at least one of (i) a friction retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side and (ii) a bonding retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include a stiffening rib attached to the first platform member.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include that the at least one first fastener is at least one of a bolt, a snap bolt, a preload washer, and a crimped metal band.

In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engines may include that an end of the first platform member proximate the first tab includes a retention snap end configured to engage with an end of the second platform member proximate the first tab such that the first tab is disposed between the end of the first platform member and the end of the second platform member.

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter is particularly pointed out and distinctly claimed at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic cross-sectional illustration of a gas turbine engine;

FIG. 2 is a schematic illustration of a portion of a fan section of the gas turbine engine that may employ embodiments of the present disclosure;

FIG. 3A is a schematic illustration of a hub assembly that may employ embodiments of the present disclosure;

FIG. 3B is a cross-sectional illustration of a portion of the hub assembly ofFIG. 3A as viewed along theline3B-3B;

FIG. 4A is a leading edge, isometric illustration of a blade assembly in accordance with an embodiment of the present disclosure;

FIG. 4B is an enlarged trailing edge, elevation illustration of the blade assembly ofFIG. 4A;

FIG. 4C is a side elevation illustration of the blade assembly ofFIG. 4A;

FIG. 5A is a side elevation illustration of a blade of a blade assembly in accordance with an embodiment of the present disclosure;

FIG. 5B is an enlarged illustration of a leading edge portion of the blade ofFIG. 5A;

FIG. 5C is an enlarged illustration of a trailing edge portion of the blade ofFIG. 5A;

FIG. 6 is an isometric illustration of platform members of a blade assembly in accordance with an embodiment of the present disclosure;

FIG. 7 is a top-down plan view illustration of a blade assembly in accordance with an embodiment of the present disclosure;

FIG. 8 is a cross-sectional illustration of a platform member in accordance with an embodiment of the present disclosure;

FIG. 9 is an illustration of multiple platform assemblies arranged in accordance with an embodiment of the present disclosure;

FIG. 10 is an illustration of an attachment configuration of a blade assembly in accordance with an embodiment of the present disclosure;

FIG. 11 is an illustration of an attachment configuration of a blade assembly in accordance with an embodiment of the present disclosure;

FIG. 12 is an illustration of an attachment configuration of a blade assembly in accordance with an embodiment of the present disclosure; and

FIG. 13 is an illustration of an attachment configuration of a blade assembly in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Detailed descriptions of one or more embodiments of the disclosed apparatus and/or methods are presented herein by way of exemplification and not limitation with reference to the Figures.

FIG. 1 schematically illustrates agas turbine engine20. Thegas turbine engine20 is disclosed herein as a turbofan that generally incorporates afan section22, acompressor section24, acombustor section26 and aturbine section28. Thefan section22 drives air along a bypass flow path B in a bypass duct, while thecompressor section24 drives air along a core flow path C for compression and communication into thecombustor section26 then expansion through theturbine section28. Theexemplary engine20 generally includes alow speed spool30 and ahigh speed spool32 mounted for rotation about an engine central longitudinal axis A relative to an enginestatic structure36 viaseveral bearing systems38. It should be understood that various bearingsystems38 at various locations may alternatively or additionally be provided, and the location of bearingsystems38 may be varied as appropriate to the application.

Thelow speed spool30 generally includes aninner shaft40 that interconnects afan42, alow pressure compressor44 and alow pressure turbine46. Theinner shaft40 can be connected to thefan42 through a speed change mechanism, which in exemplarygas turbine engine20 is illustrated as a gearedarchitecture48 to drive thefan42 at a lower speed than thelow speed spool30. Thehigh speed spool32 includes anouter shaft50 that interconnects ahigh pressure compressor52 andhigh pressure turbine54. Acombustor56 is arranged inexemplary gas turbine20 between thehigh pressure compressor52 and thehigh pressure turbine54. An enginestatic structure36 is arranged generally between thehigh pressure turbine54 and thelow pressure turbine46. The enginestatic structure36 furthersupports bearing systems38 in theturbine section28. Theinner shaft40 and theouter shaft50 are concentric and rotate via bearingsystems38 about the engine central longitudinal axis A which is collinear with their longitudinal axes.

The core airflow is compressed by thelow pressure compressor44 then thehigh pressure compressor52, mixed and burned with fuel in thecombustor56, then expanded over thehigh pressure turbine54 andlow pressure turbine46. The

turbines

46,54 rotationally drive the respectivelow speed spool30 andhigh speed spool32 in response to the expansion. It will be appreciated that each of the positions of thefan section22,compressor section24,combustor section26,turbine section28, and fandrive gear system48 may be varied. For example,gear system48 may be located aft ofcombustor section26 or even aft ofturbine section28, andfan section22 may be positioned forward or aft of the location ofgear system48.

Theengine20 in one example is a high-bypass geared aircraft engine. In a further example, theengine20 bypass ratio is greater than about six (6), with an example embodiment being greater than about ten (10), the gearedarchitecture48 is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3 and thelow pressure turbine46 has a pressure ratio that is greater than about five. In one disclosed embodiment, theengine20 bypass ratio is greater than about ten (10:1), the fan diameter is significantly larger than that of thelow pressure compressor44, and thelow pressure turbine46 has a pressure ratio that is greater than about five 5:1.Low pressure turbine46 pressure ratio is pressure measured prior to inlet oflow pressure turbine46 as related to the pressure at the outlet of thelow pressure turbine46 prior to an exhaust nozzle. The gearedarchitecture48 may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. Thefan section22 of theengine20 is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet (10,688 meters). The flight condition of 0.8 Mach and 35,000 ft (10,688 meters), with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.45. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram ° R)/(514.7° R)]^0.5. The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150 ft/second (350.5 m/sec).

Although thegas turbine engine20 is depicted as a turbofan, it should be understood that the concepts described herein are not limited to use with the described configuration, as the teachings may be applied to other types of engines such as, but not limited to, turbojets and turboshafts, wherein an intermediate spool includes an intermediate pressure compressor (“IPC”) between a low pressure compressor (“LPC”) and a high pressure compressor (“HPC”), and an intermediate pressure turbine (“IPT”) between the high pressure turbine (“HPT”) and the low pressure turbine (“LPT”).

FIG. 2 is a schematic view of a portion of afan section200 that may employ various embodiments disclosed herein (e.g.,region90 shown inFIG. 1).Fan section200 includes a plurality of airfoils, including, for example, one or more fan blades202 (generically an “airfoil”). Theairfoils202 may be hollow bodies with internal cavities defining a number of channels or cavities, may be hollow, or may be solid-body. Theairfoils202 may be mounted or attached to ahub204 that is mounted to or part of a gas turbine engine (e.g., as shown inFIG. 1). In this illustration, located betweenadjacent airfoils202 are a plurality ofplatforms206. Theplatforms206 may be attached to thehub204 by one or more locking pins208. Theairfoils202 may be similarly attached to thehub204 by one or more locking pins or other attachment mechanisms, as will be appreciated by those of skill in the art. The airfoil extends in a generally axial direction (i.e., with respect to an engine axis) from aleading edge210 to a trailingedge212.

Thefan section200 is housed within a case of a gas turbine engine, which may have multiple parts (e.g., fan case, turbine case, diffuser case, etc.). In various locations, components, such as seals, may be positioned between theairfoils202 and the fan case. For example, as appreciated by those of skill in the art, blade outer air seals (“BOAS”) may be arranged radially outward from a tip of theairfoil202. As will be appreciated by those of skill in the art, the BOAS can include BOAS supports that are configured to fixedly connect or attach the BOAS to the fan case (e.g., the BOAS supports can be located between the BOAS and the fan case). As theairfoils202 are rotated within the fan case, theairfoils202 will direct air in a radially aftward direction and into anengine inlet214, with at least a portion of such air being directed to compressor and turbine sections of a gas turbine engine (e.g., as shown inFIG. 1).

Thehub204 is rotatable within a gas turbine engine, and may be rotated relative to a stationary portion of the engine (e.g., the engine inlet214). Forward of the hub204 (and theairfoil202 and the platform206) may be aspinner216, as will be appreciated by those of skill in the art. Thespinner216 may rotate with rotation of thefan section200 and streamline airflow into thefan section200. The incoming air is driven aftward by theairfoils202 and flows along a flow orgaspath surface218 of theplatforms206 arranged betweenadjacent airfoils202 arranged about a circumference of thehub204.

Turning now toFIGS. 3A-3B, schematic illustrations of ahub assembly300 of a gas turbine engine are shown.FIG. 3A is an isometric illustration of thehub assembly300 andFIG. 3B is a cross-sectional view of thehub assembly300 as viewed along theline3B-3B ofFIG. 3A. Thehub assembly300, as shown, includes ahub302, a fan blade304, and aplatform306. The fan blade304 may be a fan blade (e.g., forfan section22 shown inFIG. 1) or a turbine blade (e.g., for acompressor section24 orturbine section28 shown inFIG. 1). Although shown with a single fan blade304 and asingle platform306, those of skill in the art will appreciate that a number of blades and platforms are to be installed to thehub302 when installed into a gas turbine engine. Further, although a specific configuration and arrangement of elements is shown, those of skill in the art will appreciate that alternative arrangements are possible without departing from the scope of the present disclosure. That is, the present illustrations and discussion are merely for illustrative and explanatory purposes and are not intended to be limiting.

Thehub assembly300 may be installed within a fan section of a gas turbine engine. As shown, thehub302 includes at least oneattachment lug308. The fan blade304 is installed between twoadjacent attachment lug308 within ablade cavity310. During installation of the fan section, theplatform306 is operably coupled to each of theattachment lug308. As shown, each of theattachment lug308 may include one ormore slots312 that are configured to receive a portion of arespective platform306. For example, as shown, afront end314 of theplatform306 may include afirst connector316 that may engage within arespective slot312, and atrear end318 of theplatform306, asecond connector320 may engage with arespective slot312. A lockingpin322 may be used to provide removable attachment between theplatform306 and theattachment lug308.

Thefirst connector316 and thesecond connector320 extend from anon-gaspath surface324 of theplatform306, as will be appreciated by those of skill in the art. Opposite thenon-gaspath surface324 of theplatform306 is agaspath surface326, which may be contoured as appreciated by those of skill in the art. Each of the

connectors

316,320 include securing

elements

328,330, respectively, defining apertures for attachment. To secure theplatform306 to arespective attachment lug308, thefirst connector316 is inserted into arespective slot312 at thefront end314 and thesecond connector320 is inserted into arespective slot312 at therear end318. Thelocking pin322 is inserted through anattachment aperture332 to pass through each of the securing

elements

328,330 of theplatform306 and thus through thefirst connector316 and thesecond connector320.

As shown inFIGS. 3A-3B, theplatform306 is a separate component of the hub-rotor assembly, with thelocking pin322 functioning as a retention feature. The sides of theplatform306 may be configured with seals to prevent air leakage, with such seals arranged at the interface or space between an edge of theplatform306 and a side of the fan blade304. Theplatform306 is configured to guide air into a core compressor inlet of a gas turbine engine, and prevent air from leaking beneath the flow surface of theplatform306. Platforms are typically made from light materials and minimal use thereof such that the platforms do not impact overall weight and/or to minimize impact if a fan blade out event occurs. Given that each rotor-blade configuration may be unique, a unique and specific platform may be required for each rotor or engine design, which may impact costs and development time thereof.

Embodiments of the present disclosure are directed to eliminating the rotor-mounted platforms and providing for a fan blade-mounted platform. Advantageously, such configuration may address concerns related to manufacturing, weight, fan blade designs, etc. In accordance with some embodiments of the present disclosure, two platform members are arranged on opposing sides of a fan blade and are fixedly attached to each other and one or more tabs of the fan blade. In some embodiments, one or more mechanisms for attaching or mounting the platform members to the fan blade may be employed. For example, attachment may be provided by fasteners, snap retention, crimp or clip retention, bonding, etc.

Turning now toFIGS. 4A-4C, schematic illustrations of ablade assembly400 in accordance with an embodiment of the present disclosure are shown.FIG. 4A is a leading edge, isometric illustration of theblade assembly400,FIG. 4B is an enlarged trailing edge, elevation illustration of theblade assembly400, andFIG. 4C is a side elevation illustration of theblade assembly400. Theblade assembly400 is configured to be installed to, mounted in, or otherwise attached to a rotor for installation within a gas turbine engine, as described above.

Theblade assembly400 includes afan blade402, afirst platform member404, and asecond platform member406, with the first and

second platform members

404,406 mounted or attached to thefan blade402 on opposite sides of thefan blade402. Thefan blade402 has aleading edge408, a trailingedge410, afirst side412, and asecond side414. When installed within a gas turbine engine, theleading edge408 is generally forward of the trailingedge410, with a gaspath flowing in a direction from theleading edge408 to the trailingedge410. The first and

second sides

412,414 of thefan blade402 are airfoil surfaces that extend between theleading edge408 and the trailingedge410. Thefan blade402 may extend in a generally radial direction (i.e., relative to an engine axis when installed in a gas turbine engine) from aroot416 at a radially inward end to atip418 at a radially outward end. Theroot416 is configured for installation and/or attachment to a hub.

Thefirst platform member404 is mounted or attached to thefan blade402 on thefirst side412 and thesecond platform member406 is mounted or attached to thefan blade402 on thesecond side414. Thefirst platform member404 is attached, in this embodiment, to thesecond platform member406 by a plurality offasteners420. Further, thefasteners420 are configured to directly connect and attach thefirst platform member404 and thesecond platform member406 to thefan blade402. The connection may be proximate both theleading edge408 and the trailingedge410 through one or moreblade engagement tabs422. That is, thefan blade402 may include one or moreblade engagement tabs422 that extend from the shape or geometry of thefan blade402, proximate theroot416, at one or both of theleading edge408 and the trailingedge410 and include apertures or other structure to receive thefasteners420 and allow for fixed engagement of the three parts together (i.e., theblade engagement tab422, a portion of thefirst platform member404, and a portion of the second platform member406).

Accordingly, the platforms of the present disclosure of a two-part constructions, with the two

platform members

404,406 being directly mounted and attached to aspecific fan blade402. The joining or coupling of the three components may be by multiple mechanisms, including, but not limited to, bolted or other fastener connection, friction retention, and/or bonding retention (e.g., epoxy). The fastener connection provides for a direct, mechanical joining between the separate components. The friction retention is provided between surfaces of the platform members and the exterior surfaces of the fan blade. The bonding retention may provide for a material or chemical bonding between the material of the platform members and the body or surfaces of the fan blade.

FIG. 5 is a schematic illustration of afan blade502 that may be configured to have platform members mounted thereto, in accordance with an embodiment of the present disclosure. Specifically,FIG. 5 illustrates thefan blade502 without the platform members mounted thereto.FIG. 5 is an enlarged side view elevation of thefan blade502 proximate aroot516 of thefan blade502.

As shown, thefan blade502 includes afirst tab524 located proximate theroot516 and arranged along aleading edge508 of thefan blade502. Similarly, in this embodiment, thefan blade502 includes asecond tab526 located proximate theroot516 and arranged along a trailingedge510 of thefan blade502. The

tabs

524,526 each includerespective apertures528 or through-holes to receive a fastener and enable mounting or attachment of platform members to thefan blade502. The

tabs

524,526 may be formed from the same material of thefan blade502 and are forward (from leading edge508) and aft (from trailing edge510) extensions of the material of thefan blade502. Further, in some embodiments, the tabs described herein may be welded to the fan blade, or otherwise attached thereto.

As shown, a mountingregion530 is defined as extending from thefirst tab524 to thesecond tab526 along an exterior surface of thefan blade502. The mountingregion530 is configured to engage with and contact a surface of a mounted platform member (e.g., an interior or inner facing surface of the platform member). In some embodiments, the mountingregion530 may be smooth or substantially smooth with no features thereon. In such configurations, a platform member may be in contact with all parts of the mountingregion530. In other embodiments, the mountingregion530 may include one or more mounting features, such as a roughened surface, ribs, or other structures and/or texture to provide for increased securing of the platform member to thefan blade502. For example, such ribbed structure for engagement between the platform members and the fan blade is shown and described in U.S. Pat. No. 9,896,949, entitled “Bonded Fan Platform,” issued on Feb. 20, 2018, assigned to the present Applicant; the contents of which are incorporated herein in their entirety. In some embodiments, theapertures528 may be reinforced with a grommet or other similar structure.

Turning now toFIG. 6, a schematic illustration of two

platform members

604,606 arranged without the fan blade are shown. The

platform members

604,606 are configured to be installed on opposite sides of a fan blade and may be connected to each other and the fan blade (e.g., through tabs of the fan blade). Afirst platform member604 may be arranged on a first side of a fan blade and asecond platform member606 may be arranged on a second side of the fan blade and opposite the first side/first platform member604. The two

platform members

604,606 may be connected by one ormore fasteners620, such as bolts or rivets, although other types of fasteners are contemplated without departing from the scope of the present disclosure.

As shown, thefirst platform member604 includes arespective contact surface632 and thesecond platform member606 includes arespective contact surface634. The contact surfaces632,634 are contoured to enable engagement with a surface of the fan blade (e.g., a mounting surface as shown inFIG. 5). The geometry and contour of the contact surfaces632,634 may be selected and configured to engage with the mounting region/surface of the fan blade, at least when thefasteners620 are fixedly engaged and securing the two

platform members

604,606 to the fan blade. As such, prior to installation and mounting, the geometry of theplatform members604,608 may be selected to provide for a pre-load at the point of connection (e.g., between the fan blade tabs and the ends of the platform members).

Also shown inFIG. 6 is astiffening rib636 that may be connected to or attached to one or both of the

platform members

604,606. The stiffeningrib636 may be provide to increase a stiffness or rigidity of the assembled structure (i.e., the platform members mounted to a fan blade). The stiffeningrib636 may be attached by brazing, welding, adhesives, mechanical fixture (e.g., fastener), or other attachment means/mechanism, as will be appreciated by those of skill in the art.

Turning now toFIG. 7, a top down plan view of ablade assembly700 before mounting is shown. As illustrated, two

platform members

704,706 are arranged adjacent to afan blade702, and arranged on opposite sides of thefan blade702. Thefan blade702,first platform member704, andsecond platform member706 may be arranged and configured as discussed above. As shown thefirst platform member704 is arranged proximate afirst side712 of thefan blade702 and thesecond platform member706 is arranged proximate asecond side714 of thefan blade702. Thefirst platform member704 has arespective contact surface732 that faces thefan blade702 on thefirst side712 and is arranged to contact thefan blade702 along a mounting region on thefirst side712 of thefan blade702. Thesecond platform member706 has arespective contact surface734 that faces thefan blade702 on thesecond side714 and is arranged to contact thefan blade702 along a mounting region on thesecond side714 of thefan blade702. As shown, a geometry or contour of thecontact surface732 of thefirst platform member704 is different than the geometry or contour of thefirst side712 of thefan blade702 and a geometry or contour of thecontact surface734 of thesecond platform member706 is different than the geometry or contour of thesecond side714 of thefan blade702. These differences in geometry or contour of the

platform members

704,706 relative to thefan blade702 ensure uniform frictional contact along the length of thefan blade712 when the first and

second platform members

704,706 are joined together by one or more fasteners through tabs of thefan blade702, as described above.

Turning now toFIG. 8, a schematic cross-sectional illustration of aplatform member804 illustrating an interior construction thereof is shown. Theplatform member804 may be similar to that shown and described above. In this illustrative constructions, theplatform member804 is formed from acore838 that is wrapped by one ormore plys840. Thecore838 may be a metallic core (e.g., aluminum) or a foam core, and may have a honeycomb structure to enable reduced weight and other properties. Theplys840 may be carbon fiber plys that define surfaces of theplatform member804, including acontact surface832 for engaging with a surface of a fan blade and anairflow surface842, with theairflow surface842 arranged between adjacent fan blades on a hub when installed within a gas turbine engine. Thecontact surface832 of theplatform member804 may be a smooth surface.

Turning now toFIG. 9, a schematic illustration of two

adjacent blade assemblies

900a,900bas would be installed to a hub (not shown) is provided. As shown, afirst blade assembly900aincludes arespective fan blade902a, afirst platform member904aarranged on a first side of thefan blade902a, and asecond platform member906aattached a second side of thefan blade902a. Similarly, asecond blade assembly900bincludes arespective fan blade902b, afirst platform member904barranged on a first side of thefan blade902b, and asecond platform member906battached a second side of thefan blade902b. When installed to a hub, thesecond platform member906aof thefirst blade assembly900ais arranged adjacent to thefirst platform member904bof thesecond blade assembly900b. As such, thesecond platform member906aof thefirst blade assembly900aand thefirst platform member904bof thesecond blade assembly900bdefine a flow path between thefirst fan blade902aand thesecond fan blade902b.

Because thefirst blade assembly900ais separate from thesecond blade assembly900b, agap944 is formed between the edges of thesecond platform member906aof thefirst blade assembly900aand thefirst platform member904bof thesecond blade assembly900b. To prevent ingestion of air between the

blade assemblies

900a,900b, aseal946amay be provided to at least partially seal thegap944. In this illustrative embodiment, theseal946ais a flap seal that is under-mounted or fixed to a bottom (non-gaspath) surface of thesecond platform member906aof thefirst blade assembly900a. Theseal946amay be bonded or otherwise affixed to thesecond platform member906aof thefirst blade assembly900a. Theseal946awill engage with a bottom (non-gaspath) surface of thefirst platform member904bof thesecond blade assembly900b, thus sealing thegap944 formed therebetween. As shown, thesecond platform member906bof thesecond blade assembly900bmay also include aseal946bthat will sealingly engage with a first platform member of an adjacent blade assembly (not shown).

The first and

second platform members

904a,906aof thefirst blade assembly900aare joined and connected to thefirst fan blade902aby one ormore fasteners920a. Similarly, the first and

second platform members

904b,906bof thesecond blade assembly900bare joined and connected to thesecond fan blade902bby one ormore fasteners920b. Thefasteners920aare arranged to pass through ends of the first and

second platform members

904a,906aand atab924aof thefirst fan blade902ato attach the

platform members

904a,906ato thefirst fan blade902a. Similarly, thefasteners920bare arranged to pass through ends of the first and

second platform members

904b,906band atab924bof thesecond fan blade902bto attach the

platform members

904b,906bto thesecond fan blade902b.

Turning now toFIGS. 10-13, various different joining mechanisms for joining two platform members to a tab of a fan blade in accordance with embodiments of the present disclosure are shown.

FIG. 10 illustrates an end of afirst platform member1004 and an end of asecond platform member1006 attached to atab1024 of a fan blade (e.g., as shown and described above). The elements are joined together byfasteners1020. In this embodiment, thefasteners1020 include snap ends1048 on the fasteners1020 (i.e., thefasteners1020 are snap bolts in this embodiment). The snap ends1048 provide for secure coupling of the end of thefirst platform member1004, the end of thesecond platform member1006, and thetab1024.

FIG. 11 illustrates an end of afirst platform member1104 and an end of asecond platform member1106 attached to atab1124 of a fan blade (e.g., as shown and described above). The elements are joined together byfasteners1120. In this embodiment, thefasteners1120 includepreload washers1150 between the

adjacent elements

1104,1124,1106. Further, thefasteners1120 includelock nuts1152 on an end thereof, to provide secure coupling of the end of thefirst platform member1104, the end of thesecond platform member1106, and thetab1124.

FIG. 12 illustrates an end of afirst platform member1204 and an end of asecond platform member1206 attached to atab1224 of a fan blade (e.g., as shown and described above). The elements are joined together by afastener1220. In this embodiment, thefastener1220 is a metal band that is crimped and secures the elements together to provide secure coupling of the end of thefirst platform member1204, the end of thesecond platform member1206, and thetab1224.

FIG. 13 illustrates an end of afirst platform member1304 and an end of asecond platform member1306 attached to atab1324 of a fan blade (e.g., as shown and described above). The elements are joined together by fasteners1320 (having lock nuts1352). In this embodiment, the end of thefirst platform member1304 includes retention snap ends1354. The retention snap ends1354 of the end of thefirst platform member1304 are configured to engage with the end of thesecond platform member1306, and provide for secure coupling of the end of thefirst platform member1304, the end of thesecond platform member1306, and thetab1324.

Advantageously, embodiments of the present disclosure provide for improved platform construction as compared to typical platforms for gas turbine engines. For example, embodiments of the present disclosure are directed to platform members that are mounted and affixed to fan blades such that a separate and distinct platform is not required to be designed, even when fan blade design is changed. Moreover, because the platform members may be arranged with a general geometry, such platform members may be employed on various different fan blade configurations, without requiring a complete redesign of such platform members.

Further, advantageously, because multiple different retention and attaching mechanisms may be employed in various embodiments, a reduced risk of foreign object damage from a platform member breaking or failing—i.e., the retention will retain the platform members to the fan blades proximate the root of the blades, even when a fan blade fails or breaks.

Further, advantageously, because the platform members may be attached to the fan blades prior to installation to a hub, assembly of the entire fan section of a gas turbine engine may be simplified. Specifically, there is no need to mount the platforms to the hub separately from the fan blades.

Furthermore, advantageously, because the platform members are mounted and affixed to the fan blades, fewer attachment points to a hub are required, thus reducing the number of design constraints.

As used herein, the term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” may include a range of ±8%, or 5%, or 2% of a given value or other percentage change as will be appreciated by those of skill in the art for the particular measurement and/or dimensions referred to herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. It should be appreciated that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” “radial,” “axial,” “circumferential,” and the like are with reference to normal operational attitude and should not be considered otherwise limiting.

While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations, or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments.

Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

What is claimed is:

1. A blade assembly for a gas turbine engine, the blade assembly comprising:

a fan blade having a leading edge, a trailing edge, a root, a tip, a first side, and a second side, the fan blade having a first tab extending from the leading edge proximate the root and a second tab extending from the trailing edge proximate the root;

a first platform affixed to the first side of the fan blade at the first tab and the second tab and extending in a direction from the leading edge to the trailing edge along the first side; and

a second platform affixed to the second side of the fan blade at the first tab and the second tab and extending in a direction from the leading edge to the trailing edge along the first side;

at least one first fastener connecting the first platform, the first tab, and the second platform; and

at least one second fastener connecting the first platform, the second tab, and the second platform.

2. The blade assembly ofclaim 1, wherein the fan blade defines a mounting region extending from the first tab to the second tab on each of the first side and the second side.

3. The blade assembly ofclaim 2, wherein a friction retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side.

4. The blade assembly ofclaim 2, wherein a bonding retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side.

5. The blade assembly ofclaim 4, wherein the bonding interface includes an epoxy to bond a material of the first platform member to the first side of the fan blade.

6. The blade assembly ofclaim 2, wherein the mounting region of the fan blade comprises a smooth surface.

7. The blade assembly ofclaim 2, wherein the mounting region of the fan blade comprises at least one rib configured to engage with a contact surface of the first platform member.

8. The blade assembly ofclaim 1, wherein at least one of (i) the first platform member defines a geometry different than a geometry of the first side of the fan blade such that a pre-load is defined by the first platform member and (ii) the second platform member defines a geometry different than a geometry of the second side of the fan blade such that a pre-load is defined by the second platform member.

9. The blade assembly ofclaim 1, further comprising a stiffening rib attached to the first platform member.

10. The blade assembly ofclaim 1, wherein the at least one first fastener is at least one of a bolt, a snap bolt, a preload washer, and a crimped metal band.

11. The blade assembly ofclaim 1, wherein an end of the first platform member proximate the first tab includes a retention snap end configured to engage with an end of the second platform member proximate the first tab such that the first tab is disposed between the end of the first platform member and the end of the second platform member.

12. The blade assembly ofclaim 1, further comprising a seal attached to at least one of the first platform member and the second platform member.

13. A gas turbine engine comprising:

a hub; and

a blade assembly mounted to the hub, wherein the blade assembly comprises:

14. The gas turbine engine ofclaim 13, further comprising a plurality of additional blade assemblies distributed about a circumference of the hub.

15. The gas turbine engine ofclaim 14, further comprising a seal attached to at least one of the first platform member and the second platform member, wherein the seal provides a seal between the blade assembly and an adjacent one of the plurality of additional blade assemblies.

16. The gas turbine engine ofclaim 13, wherein the fan blade defines a mounting region extending from the first tab to the second tab on each of the first side and the second side.

17. The gas turbine engine ofclaim 16, wherein at least one of (i) a friction retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side and (ii) a bonding retention interface is formed between the fan blade at the mounting region and a contact surface of the first platform on the first side.

18. The gas turbine engine ofclaim 13, further comprising a stiffening rib attached to the first platform member.

19. The gas turbine engine ofclaim 13, wherein the at least one first fastener is at least one of a bolt, a snap bolt, a preload washer, and a crimped metal band.

20. The gas turbine engine ofclaim 13, wherein an end of the first platform member proximate the first tab includes a retention snap end configured to engage with an end of the second platform member proximate the first tab such that the first tab is disposed between the end of the first platform member and the end of the second platform member.