Airfoil components

Abstract

An airfoil assembly for a turbine engine defines an axial direction, a radial direction, and a circumferential direction, and includes a first airfoil defining a first end in the radial direction, a first hub disposed at the first end of the first airfoil and having a first extension member extending at least partially in the radial direction, and a second airfoil adjacent to the first airfoil, the second airfoil defining a first end in the radial direction, the second hub disposed at the first end of the second airfoil and including a second extension member extending at least partially in the radial direction, and a circumferential biasing assembly operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both.

Description

Technical Field

[0001] The present subject matter generally relates to gas turbine engines. More specifically, the present subject matter relates to a shroud assembly for an airfoil of a gas turbine engine. Background Art

[0002] Gas turbine engines include various components that are subject to high temperatures. As an example of such components, turbine airfoils downstream of the combustor of a gas turbine engine are subject to extremely high temperatures.

[0003] For components that are subjected to such high temperatures, non-traditional high temperature composite materials, such as ceramic matrix composite (CMC) materials, may be used. Composite materials generally include a reinforcement material and a matrix material. CMC material is a composite material in which both the reinforcement material and the matrix material are formed of ceramic. The reinforcement material and the matrix material may be formed of the same type of ceramic or different types of ceramics. Components made of CMC materials have higher temperature bearing capabilities compared to typical components (e.g., metal components), which may allow for improved component performance and / or increased system temperatures while reducing cooling flow to the CMC components. Summary of the invention

[0004] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0005] According to one or more embodiments, an airfoil assembly for a turbine engine defines an axial direction, a radial direction, and a circumferential direction, and includes a first airfoil defining a first end in the radial direction; a first hub, which is disposed at the first end of the first airfoil and includes a first extension member extending at least partially in the radial direction; a second airfoil adjacent to the first airfoil, the second airfoil defining a first end in the radial direction; a second hub, which is disposed at the first end of the second airfoil and includes a second extension member extending at least partially in the radial direction, and a circumferential offset assembly, which is capable of operating with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both.

[0006] According to one or more embodiments, the circumferential biasing assembly is a first shroud assembly, and the first shroud assembly includes a first spring member coupled to, positioned adjacent to, or both the first extension member.

[0007] According to one or more embodiments, the airfoil assembly further includes a second circumferential biasing assembly configured as a second shroud assembly, the second shroud assembly including a second spring member coupled to the second extension member, positioned adjacent to the second extension member, or both, and the first spring member is configured to apply a circumferential load to the second hub.

[0008] According to one or more embodiments, the first hub and the second hub are torsion springs, and the first hub applies a torsion force on the second hub.

[0009] According to one or more embodiments, the airfoil assembly further includes a plurality of adjacent airfoils in addition to the first and second airfoils, the plurality of adjacent airfoils including a third airfoil at one end of the plurality of adjacent airfoils and a fourth airfoil at the other end of the plurality of adjacent airfoils, the third airfoil being adjacent to the second airfoil and the second spring member of the second airfoil applying a circumferential load to a third hub disposed on the third airfoil, and the fourth airfoil being adjacent to the first airfoil and the fourth spring member of the fourth airfoil applying a circumferential load on the first hub.

[0010] According to one or more embodiments, the first extension member is part of a first pair of extension members, the first pair of extension members are spaced apart in the axial direction to define a first space therebetween, and the first shroud assembly is disposed in the first space between the first pair of extension members.

[0011] According to one or more embodiments, the airfoil assembly further includes a second airfoil adjacent to the first airfoil, the second airfoil defining a first end in a radial direction; a second hub disposed at the first end of the second airfoil and including a second pair of extension members extending at least partially in a radial direction, the second pair of extension members being spaced apart in an axial direction to define a second space therebetween; and a second circumferential biasing assembly configured as a second shroud assembly, the second shroud assembly including a second spring member disposed in a second space between the second pair of extension members, and the first spring member being configured to apply a circumferential load to the second hub.

[0012] According to one or more embodiments, the second hub includes an axial wall extending in an axial direction from one of the second pair of extension members, and the first spring member applies a circumferential load on the axial wall.

[0013] In accordance with one or more embodiments, the second spring member is attached to the other of the second pair of extension members.

[0014] According to one or more embodiments, the first shield assembly further includes a sealing element coupled to or formed with the first spring member.

[0015] According to one or more embodiments, the first spring member is a metal leaf spring.

[0016] According to one or more embodiments, the first end of the first airfoil on which the first hub is disposed is an inner end in a radial direction.

[0017] According to one or more embodiments, the circumferential offset assembly includes a circumferential offset block at least partially positioned between a first extension member of the first hub and a second extension member of the second hub.

[0018] According to one or more embodiments, the circumferential offset block includes a wedge-shaped portion defining a tip oriented radially outward.

[0019] According to one or more embodiments, the first extension member and the second extension member each define an inclined surface, and the wedge-shaped portion is positioned between the inclined surfaces of the first extension member and the second extension member in the circumferential direction.

[0020] According to one or more embodiments, the circumferential offset block includes a wedge-shaped portion and a hook portion at least partially positioned between the first extension member of the first hub and the second extension member of the second hub, and the circumferential offset assembly further includes a retaining member at least partially positioned in the channel formed by the hook portion.

[0021] According to one or more embodiments, each of the first hub and the second hub includes a ceramic matrix composite material.

[0022] According to one or more embodiments, a turbine engine defining an axial direction, a radial direction, and a circumferential direction comprises: a compressor section; a combustion section; and a turbine section, wherein the compressor section or the turbine section comprises an airfoil assembly, the airfoil assembly comprising: a first airfoil defining a first end in a radial direction; a first hub disposed at the first end of the first airfoil and comprising a first extension member extending at least partially in a radial direction; a second airfoil adjacent to the first airfoil, the second airfoil defining a first end in a radial direction; a second hub disposed at the first end of the second airfoil and comprising a second extension member extending at least partially in a radial direction; and a circumferential offset assembly, the circumferential offset assembly being operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both.

[0023] According to one or more embodiments, the circumferential biasing assembly is a first shroud assembly, and wherein the first shroud assembly includes a spring member coupled to, positioned adjacent to, or both of the first extension member.

[0024] According to one or more embodiments, the circumferential offset assembly includes a circumferential offset block at least partially positioned between a first extension member of the first hub and a second extension member of the second hub.

[0025] These and other features, aspects and advantages of the present disclosure will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A full and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0027] Figure 1 is a schematic cross-sectional view of a gas turbine engine according to one or more embodiments.

[0028] Figure 2 According to one or more embodiments Figure 1 A cross-sectional view of a portion of a turbine rotor assembly of a turbine section of a gas turbine engine is shown in FIG.

[0029] Figure 3 According to one or more embodiments Figure 2 A cross-sectional view of a portion of a turbine rotor assembly of a turbine section of a gas turbine engine is shown in FIG.

[0030] Figure 4 is a perspective view of two wheel hubs and a hub shroud assembly after assembly according to one or more embodiments.

[0031] Figure 5 is a radial cross-sectional view of two wheel hubs and a hub shroud assembly prior to assembly according to one or more embodiments.

[0032] Figure 6 is a radial cross-sectional view of two wheel hubs and a hub shroud assembly after assembly according to one or more embodiments.

[0033] Figure 7 is a perspective view of a spring member according to one or more embodiments.

[0034] Figure 8 is a perspective view of a spring member according to one or more embodiments.

[0035] Fig. 9 is a perspective view of a spring member according to one or more embodiments.

[0036] Fig.10is a perspective view of a spring member according to one or more embodiments.

[0037] Fig.11 A flow chart illustrating a method of assembling an airfoil assembly for a turbine engine according to one or more embodiments.

[0038] Fig.12 is a rear perspective view of three wheel hubs and hub shroud assemblies after assembly according to one or more embodiments.

[0039] Fig.13 is a front perspective view of three wheel hubs and hub shroud assemblies after assembly according to one or more embodiments.

[0040] Fig.14 is a cross-sectional view of an assembled wheel hub and hub shroud assembly according to one or more embodiments.

[0041] Fig.15 is a rear perspective view of a hub shroud assembly with a wheel hub removed according to one or more embodiments.

[0042] Fig.16 is a front perspective view of a hub shroud assembly with a wheel hub removed according to one or more embodiments.

[0043] Fig.17 A flow chart illustrating a method of assembling an airfoil assembly for a turbine engine according to one or more embodiments is shown.

[0044] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention. DETAILED DESCRIPTION

[0045] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the present invention, not to limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present invention without departing from the scope or spirit of the present invention. For example, a feature illustrated or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present invention is intended to encompass these modifications and variations within the scope of the appended claims and their equivalents.

[0046] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of the respective components.

[0047] The terms "upstream" and "downstream" refer to relative directions relative to the flow of a fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid is flowing, while "downstream" refers to the direction to which the fluid is flowing.

[0048] An example of a gas turbine engine is a bladeless counter-rotating low pressure (LP) turbine engine in which blades corresponding to conventional stator blade stages are rotated in the opposite direction to the rotor blades (i.e., counter-rotating). The counter-rotating blades are attached to a rotating drum radially outside of an annulus. It is desirable that the counter-rotating blades have hub shrouds at their respective inner ends in a radial direction that remain locked during operation to provide buckling stability and acceptable aerodynamics. For example, the hub shrouds may be pre-stressed to act as torsion springs during assembly, applying a circumferential load on the hub shrouds of adjacent blades to lock the hub shrouds together.

[0049] However, the stiffness of CMC components is significantly higher than traditional materials such as metal. Although it may be beneficial to form the counter-rotating blades and corresponding hub shrouds from CMC materials, due to the higher stiffness, it may be difficult for the prestressed CMC hub shroud to provide sufficient circumferential force to keep the hub shroud locked. Therefore, a structure that provides increased circumferential force to lock the hub shroud together may be needed.

[0050] Now referring to the accompanying drawings, Figure 1 is a schematic cross-sectional view of an exemplary gas turbine engine 10 (referred to herein as "engine 10"), shown as a high bypass turbofan engine, incorporating an exemplary embodiment of a turbine section 90 according to one aspect of the present disclosure. Although further described below with reference to a turbofan engine, the present disclosure is also applicable to turbomachinery in general, including propfan engines, turbojets, turboprop engines, and turboshaft gas turbine engines, including marine and industrial turbine engines and auxiliary power units. Further, although described below as a three-spool gas turbine engine, the present disclosure is also applicable to a two-spool gas turbine engine. Figure 1 As shown, the engine 10 has a longitudinal or axial centerline axis 12 extending therethrough for reference. The engine 10 defines a circumferential direction C, a longitudinal direction L, a radial direction R, and an upstream end 99 and a downstream end 98 along the longitudinal direction L. The longitudinal direction L is alternatively referred to herein as the "axial direction".

[0051] Generally speaking, the engine 10 may include a substantially tubular casing 18 defining an annular inlet 20. The casing 18 surrounds, or at least partially surrounds, a compressor section 21, a combustion section 26, and an interdigitated turbine section 90 (referred to herein as "turbine section 90") in a serial flow arrangement. Generally speaking, the engine 10 defines the fan assembly 14, the compressor section 21, the combustion section 26, and the turbine section 90 in a serial flow arrangement from an upstream end 99 to a downstream end 98, which together form a core flow path 70. Figure 1 In the illustrated embodiment, compressor section 21 defines a high pressure (HP) compressor 24 and an intermediate pressure (IP) compressor 22. In other embodiments, fan assembly 14 may further include or define one or more stages of a plurality of fan blades 42 coupled to fan rotor 15 and / or low speed shaft 36 and extending outwardly in radial direction R from fan rotor 15 and / or low speed shaft 36. In various embodiments, the plurality of stages of a plurality of fan blades 42 coupled to low speed shaft 36 may be referred to as a low pressure (LP) compressor.

[0052] An annular fan casing or nacelle 44 circumferentially surrounds at least a portion of the fan assembly 14 and / or at least a portion of the outer casing 18. In one embodiment, the nacelle 44 may be supported relative to the outer casing 18 by a plurality of circumferentially spaced outlet guide vanes or struts 46. At least a portion of the nacelle 44 may extend above an outer portion (in the radial direction R) of the outer casing 18, thereby defining a bypass airflow passage 48 therebetween.

[0053] The turbine section 90 further includes a high-speed turbine rotor 120 and an intermediate-speed turbine rotor 130, each of which is disposed forward of or upstream 99 of one or more connecting airfoils 116 of the low-speed turbine rotor 110. The high-speed turbine rotor 120 includes a plurality of high-speed turbine airfoils 122 extending outwardly in a radial direction R. The intermediate-speed turbine rotor 130 includes a plurality of intermediate-speed turbine airfoils 132 extending outwardly in a radial direction R. Each of the plurality of high-speed turbine airfoils 122 and the intermediate-speed turbine airfoils 132 is disposed along a longitudinal direction L among the plurality of outer shroud airfoils 118 of the low-speed turbine rotor 110.

[0054] During operation of engine 10, high-speed turbine rotor 120 generally rotates at a higher rotational speed than medium-speed turbine rotor 130. Medium-speed turbine rotor 130 generally rotates at a higher speed than low-speed turbine rotor 110. During operation of engine 10, a volume of air, as schematically indicated by arrow 74, enters engine 10 through associated inlet 76 of nacelle and / or fan assembly 14. As air 74 passes through fan blades 42, a portion of the air, as schematically indicated by arrow 78, is directed or directed into bypass airflow passage 48, while another portion of the air, as schematically indicated by arrow 80, is directed or passed through fan assembly 14. Air 80 is progressively compressed as it flows through compressor section 21 toward combustion section 26.

[0055] The now compressed air flows into combustion section 26, as schematically indicated by arrows 82, where fuel is introduced, mixed with at least a portion of compressed air 82, and ignited to form combustion gases. The combustion gases flow into turbine section 90, rotating rotating components of turbine section 90 and supporting operation of respectively coupled rotating components in compressor section 21 and / or fan assembly 14.

[0056] Additional references Figure 2 , the turbine section 90 includes a turbine rotor assembly 95. The turbine rotor assembly 95 includes a first turbine rotor 110, which is arranged alternately with a second turbine rotor 120 along a longitudinal direction L. The first turbine rotor 110 includes an outer rotor 114 surrounding the second turbine rotor 120. A plurality of outer rotor airfoils 118 extend inwardly from the outer rotor 114 along a radial direction R. In various embodiments, the outer rotor 114 defines a drum or a disk in which a plurality of outer rotor airfoils 118 are fixed. For example, the plurality of outer rotor airfoils 118 may be fixed to the outer rotor 114 via hangers, slots, dovetails, pins, mechanical fasteners (e.g., bolts, nuts, rivets, tie rods, etc.), or a combination thereof.

[0057] The second turbine rotor 120 includes an inner rotor 112. A plurality of inner rotor airfoils 119 extend outwardly from the inner rotor 112 in a radial direction R. The inner rotor 112 may define a drum, a disk, a bladed disk (e.g., a blisk), or an integrally bladed rotor (IBR). The plurality of inner rotor airfoils 119 may be secured to the inner rotor 112 via hangers, slots, dovetail pins, mechanical fasteners, or a combination thereof. In various embodiments, the inner rotor 112 and the inner rotor airfoils 119 may be substantially defined as a single, unitary piece.

[0058] In one or more embodiments, generally Figure 2The turbine rotor assembly 95 provided in the embodiment of the present invention defines a counter-rotating low-speed turbine rotor assembly. The first turbine rotor 110 and the second turbine rotor 120 can each be coupled to the low-speed shaft 36. In one embodiment, the first turbine rotor 110 is coupled to the low-speed shaft 36, and the second turbine rotor 120 is coupled to the low-speed shaft 36 via a reduction assembly. The reduction assembly may include a gearbox, a gear assembly, or a hydraulic or pneumatic speed change assembly. The low-speed shaft 36 is coupled to the fan rotor 15 of the fan assembly 14 at opposite longitudinal ends.

[0059] In one or more embodiments, the second turbine rotor 120 is coupled to the high speed shaft 34, which is further coupled to the HP compressor 24 at the opposite longitudinal end. In one or more embodiments, the turbine section 90 may further include a third turbine rotor 130, which is coupled to the low pressure (LP) or intermediate pressure (IP) compressor 22 via a third shaft 35 at the opposite longitudinal end of the engine 10. In one or more embodiments, the turbine rotor assembly 95 described herein may include a first turbine rotor 110, which surrounds one or more of the second turbine rotor 120, the third turbine rotor 130, or both. In one or more embodiments, the first turbine rotor 110 is in a counter-rotating arrangement relative to the second turbine rotor 120, the third turbine rotor 130, or both.

[0060] The turbine rotor assembly 95 may generally define a first turbine rotor 110 that is at least partially independently rotatable relative to a second turbine rotor 120. For example, the first turbine rotor 110 may define a substantially fixed or proportional speed relative to the second turbine rotor 120. As another example, the first turbine rotor 110 may be defined as being independently rotatable relative to the second turbine rotor 120 or the third turbine rotor 130, or both.

[0061] However, it will be understood that Figure 1 and Figure 2 The exemplary gas turbine engine of is provided as an example only, and in other exemplary embodiments, the gas turbine engine may have any other suitable configuration. For example, the engine may include any other suitable number or configuration of shafts / spools, compressors, turbines, etc. In addition, for example, while the exemplary gas turbine engine is depicted as a turbofan engine, in other embodiments, it may be configured as a turboprop engine, a turbojet engine, a turboshaft engine, etc. In addition, in other exemplary embodiments, the gas turbine engine may be incorporated into an aerospace vehicle, or alternatively configured for use in an aero-derivative vehicle, for land-based power generation, etc.

[0062] Now refer to Figures 3 to 6 ,in Figure 3 According to one or more embodiments Figure 2A cross-sectional view of a portion of a turbine rotor assembly of a turbine section of a gas turbine engine is shown in, Figure 4 is a perspective view of two wheel hubs 300 and a wheel hub guard assembly 400 after assembly according to one or more embodiments, Figure 5 is a cross-sectional view in the radial direction R of two hubs 300 and a hub shield assembly 400 before assembly according to one or more embodiments, and Figure 6 The two wheel hubs 300 and the wheel hub guard assembly 400 after assembly according to one or more embodiments correspond to Figure 3 A cross-sectional view in the radial direction along line 6-6.

[0063] Especially refer to Figure 3 and Figure 4 , the hub 300 shown is disposed on the inner side of each outer rotor airfoil 118 in the radial direction R. That is, each outer rotor airfoil 118 extends outward in the radial direction R from the outer surface of the hub 300 in the radial direction R. According to one or more embodiments, the outer rotor airfoil 118 and the corresponding hub 300 are formed of CMC material. According to one or more embodiments, the outer rotor airfoil 118 and the corresponding hub 300 are integrally formed.

[0064] According to one or more embodiments, the hub 300 is a parallelogram and includes an upstream hub portion 301, a downstream hub portion 302, and a central hub portion 304. The upstream hub portion 301, the downstream hub portion 302, and the central hub portion 304 together form a hub shroud. According to one or more embodiments, the first radially extending member 320 and the second radially extending member 330 extend inwardly from the radial inner surface of the hub 300 in the radial direction R, with a space formed therebetween. The first radial member 320 and the second radial member 330 may extend from one edge of the hub 300 to the other edge of the hub 300 along the circumferential direction C. Each hub 300 is interlocked with the adjacent hub 300, and the hub 300 extends completely around the axial centerline axis 12 of the engine 10. According to one or more embodiments, the first radially extending member 320 and the second radially extending member 330 are formed as radial walls. Chamfers may be formed at the bases of the first radially extending member 320 and the second radially extending member 330.

[0065] According to one or more embodiments, the upstream hub portion 301 includes a first circumferential edge 303 and a second circumferential edge 305, and the downstream hub portion 302 includes a first circumferential edge 307 and a second circumferential edge 309. Figure 5 In addition, the central hub portion 304 can include a first circumferential edge 312 and a second circumferential edge 314 .

[0066] According to one or more embodiments, a hub shroud assembly 400 is disposed on each hub 300. Hub shroud assembly 400 includes a sealing element 401 disposed on the innermost edge in radial direction R of first radially extending member 320 and second radially extending member 330. Sealing element 401 may extend further upstream than first radially extending member 320 and further downstream than second radially extending member 330. Sealing element 401 may extend from one circumferential edge of first radially extending member 320 and second radially extending member 330 to the other. Furthermore, as will be appreciated, sealing element 401 may interact with features of inner rotor 112, such as the teeth of the inner rotor, to prevent relatively high pressure air from traveling around airfoil 118 from an upstream position to a downstream position.

[0067] According to one or more embodiments, the hubs 300 are torsionally prestressed such that, when assembled, one circumferential end of the hub 300 applies a circumferential load on the other circumferential end of the adjacent hub 300. For example, the second circumferential edge 305 of the upstream hub portion 301 of one hub 300 may apply a circumferential load on the first circumferential edge 303 of the upstream hub portion 301 of the adjacent hub 300. Additionally, the first circumferential edge 307 of the downstream hub portion 302 may apply a circumferential load on the second circumferential edge 309 of the downstream hub portion 302 of the adjacent hub 300. Because the hubs 300, once assembled, extend completely around the axial centerline axis 12 of the engine 10, the circumferential load translates over the entire circumference around the axial centerline axis 12, thereby locking the hubs 300 together in place.

[0068] According to one or more embodiments, each hub 300 includes an axial wall 310 that extends substantially in the axial direction from one of the first radially extending member 320 and the second radially extending member 330. More specifically, with particular reference to Figure 5 and 6, the axial wall 310 may extend from one of the first radially extending member 320 and the second radially extending member 330 toward the other of the first radially extending member 320 and the second radially extending member 330. Specifically, for the illustrated embodiment, the axial wall 310 extends from the first radially extending member 320 in the downstream direction. According to one or more embodiments, the axial wall 310 may extend radially along the entire radial height of the first radially extending member 320 or the second radially extending member 330. The radial wall 310 may include a first surface 311 and a second surface 313. The first surface 311 may be flush with the first circumferential edge 312 of the center hub portion 304. The second surface 313 may extend from the first radially extending member 320 toward the first circumferential edge 312 of the center hub portion 304. The second surface 313 may form a first acute angle with the first circumferential edge 312 of the center hub portion 304, and may form a second acute angle with the first radially extending member 320.

[0069] Alternatively, the axial wall 310 may extend in the upstream direction from the second radially extending member 330. With this structure, the axial wall 310 may extend in the upstream direction from the second radially extending member 330, the first surface 311 may be flush with the second circumferential edge 314 of the central hub portion 304, and the second surface 313 may extend from the second radially extending portion 320 toward the second circumferential edge 314 of the central hub portion 304. The second surface 313 may form a first acute angle with the second circumferential edge 314 of the central hub portion 304, and may form a second acute angle with the second radially extending member 330.

[0070] According to one or more embodiments, spring member 450 is positioned adjacent to and / or coupled to at least one of first radially extending member 320 and second radially extending member 330. More specifically, for the illustrated embodiment, spring member 450 is disposed in a space between first radially extending member 320 and second radially extending member 330. Spring member 450 may be disposed on an outer surface of sealing element 401 in radial direction R. According to one or more embodiments, spring member 450 is a sheet metal spring (e.g., folded or otherwise formed). Figure 5 A metal sheet having a cross-sectional shape as shown). Figure 5 As shown, the spring member 450 may have a constant thickness t. The spring member 450 may also be attached to one of the first radially extending member 320 and the second radially extending member 330. For example, Figure 4-5As shown, spring member 450 is attached to second radially extending member 330 via fastener 460. Fastener 460 may be a nut and bolt structure. Alternatively, spring member 450 may be attached to one of first radially extending member 320 and second radially extending member 330 by other attachment structures (such as welding, brazing, adhesives, or other attachment structures known in the art). According to one or more embodiments, the entire spring member 450 is disposed in the space between first radially extending member 320 and second radially extending member 330.

[0071] According to one or more embodiments, and further with reference to Figure 7 The spring member 450 includes a first portion 451 extending substantially in the circumferential direction C, a second portion 452 extending substantially adjacent to the first portion 451 in the axial direction, a third portion 454 extending substantially adjacent to the second portion 452 in the circumferential direction, and a fourth portion 456 extending substantially adjacent to the third portion 454 and the first portion 451 in the axial direction. Corners may be provided between adjacent first portions 451, second portions 452, third portions 454, and fourth portions 456. A corner between the second portion 452 and the third portion 454 may be formed as a first abutment portion 453, and a corner between the third portion 454 and the fourth portion 456 may be formed as a second abutment portion 455. According to one or more embodiments, the third portion 454 may be shorter than the first portion 451, and the second portion 452 may be shorter than the fourth portion 456. The first abutment portion 453 may have a curvature having a larger radius of curvature than the second abutment portion 455. In the particular embodiment shown, the first portion includes two openings 459 for inserting fasteners 460 .

[0072] Reference again Figure 7 , for the illustrated embodiment, the thickness t of the spring member 450 is substantially constant. However, the height of the spring member 450 in the radial direction is greater at the downstream end than at the upstream end.

[0073] Reference now Figures 8 to 10 , various alternative exemplary embodiments of the spring member 450 described above are described, labeled as spring members 450', 450", 450"'. The spring members 450', 450", 450"' can be used in the same manner as Figure 7 The exemplary spring member 450 is configured in substantially the same manner as described above. Figure 7 As described above, the first portion 451 of the spring member 450 ′, 450 ″, 450 ′″ may be attached to the second radially extending member 330 .

[0074] However, for Figures 8 to 10In the embodiment of the present invention, the spring members 450 ′, 450 ″, 450 ′″ may have substantially equal heights along the radial direction R from the upstream end to the downstream end.

[0075] Further, in certain exemplary embodiments, such as Fig. 9 and 10 In an exemplary embodiment, the spring members 450", 450"' may not be complete loops. For example, Figure 7 and Figure 8 The embodiment of is a complete loop, including the first portion 451, the second portion 452, the third portion 454 and the fourth portion 456, and the first abutment portion 453 and the second abutment portion 455. However, in contrast, Fig. 9 The spring member 450" may omit the second portion 452, so that the spring member 450" is formed by the first portion 451, the third portion 454 and the fourth portion 456 and the first abutting portion 453 and the second abutting portion, and is U-shaped. Fig.10 In the embodiment, the spring member 450'' may omit the second portion 452, the third portion 454 and the first abutting portion 453, so that the spring member 450'' is formed by the first portion 451, the fourth portion 456 and the second abutting portion 455, and is L-shaped.

[0076] Still reference Figure 5 and 6 , the assembly of the hub 300 and the spring member 450 will be explained. Figure 5 is a cross-sectional view in the radial direction R of two hubs 300 and a hub guard assembly 400 before assembly according to one or more embodiments, Figure 6 FIG. 4 is a cross-sectional view in a radial direction of two wheel hubs 300 and a hub shield assembly 400 after assembly according to one or more embodiments.

[0077] As described above, the wheel hub 300 may be pre-torsional stressed before assembly so that when the wheel hub 300 is assembled as shown in FIG. Figure 6 When assembled as shown, the torsional stress of each hub applies a circumferential load to the adjacent hub 300, thereby locking the assembled hubs 300 together. However, the torsional prestress of the hubs 300 may not be sufficient to lock the hubs 300 together. For example, if the hubs 300 are formed of CMC, due to the increased stiffness, the torsional prestress may not be sufficient to provide circumferential displacement to lock the hubs 300 together during operation.

[0078] Therefore, according to one or more embodiments, the spring member 450 is disposed in the space between the first radially extending member 320 and the second radially extending member 330. Figure 5As shown, before assembly, the spring member 450 extends beyond the second circumferential edge 314 of the central hub portion 304. However, when the hubs 300 are assembled together, the first surface 311 of the axial wall 310 abuts against the second abutment portion 455 and pushes the second abutment portion 455 toward the first circumferential edge 312 of the central hub portion 304 until the spring member 450 is completely in the space between the first radially extending member 320 and the second radially extending member 330, and the first circumferential edges 303, 314, 307 of the upstream hub portion 301, the central hub portion 304, and the downstream hub portion 302 of each hub 300 are flush or nearly flush with the second circumferential edges 305, 314, 309 of the upstream hub portion 301, the central hub portion 304, and the downstream hub portion 302 of the adjacent hub 300. When the first surface 311 of the axial wall 310 pushes the second abutment portion 455 toward the first circumferential edge 312 of the central hub portion 304, the first abutment portion 453 abuts the second surface 313 of the axial wall 310. Therefore, the second surface 313 of the axial wall 310 of each hub 300 and the first surface 311 of the axial wall 310 of the adjacent hub 300 exert relative circumferential forces on the spring member 450 to compress the spring member 450. In turn, the compressed spring member 450 exerts a circumferential load on the first surface 311 of the axial wall 310 of the adjacent hub 300, thereby locking the assembled hubs 300 together, as shown in FIG. Figure 6 shown.

[0079] According to one or more embodiments, when the spring member 450 is compressed as described above, the circumferential length of the spring member 450 at the third portion 454 may be changed from Figure 5 The first circumferential length Lc1 before assembly shown is reduced to Figure 6 A second circumferential length Lc2 after assembly is shown.

[0080] like Figure 7-8 The loop-shaped spring members 450, 450' shown can apply the maximum circumferential load. However, in some applications, less circumferential load may be sufficient to lock the hubs 300 together. In this case, a U-shaped spring member 450" or an L-shaped spring member 450"' can be used. In addition, the spring members can be other types of springs that directly or indirectly generate circumferential loads on adjacent hubs 300.

[0081] For the counter-rotating outer rotor airfoil 118, it is generally beneficial to have a hub shroud that remains locked relative to the adjacent hub shroud during operation to provide stability against buckling and acceptable aerodynamics. According to one or more embodiments, a spring element 450 is disposed in the hub 300, which itself may be prestressed to act as a torsion spring to generate the interference force necessary to lock the hub 300 together so that the hub shroud can be locked together during operation. According to one or more embodiments, the hub is formed of CMC and the spring element 450 is formed of sheet metal so that the spring element 450 is significantly softer than the hub 300, thereby allowing for greater displacement for a given force. This structure is capable of maintaining the hub shroud in a locked state over a wide range of operating conditions with deflection and inherent dimensional variations in the hardware.

[0082] Reference now Fig.11 , a flow chart of a method 500 for assembling an airfoil assembly for a turbine engine according to one or more embodiments is shown. The method 500 includes step S501, forming a plurality of airfoils 118, each airfoil 118 having a hub 300 with a pair of extension members 320, 330. According to one or more embodiments, the pair of extension members 320, 330 may be a first radial extension member 320 and a second radial extension member 330 formed as radial walls. Different embodiments of airfoils 118, hubs 300, and extension members 320, 330 that can be formed are described above.

[0083] The method 500 further includes step S502 of inserting a spring member 450 , 450 ′, 450 ″, 450 ′″ into a space defined between a pair of extension members 320 , 330 of each airfoil 118 . Various embodiments of the spring members 450 , 450 ′, 450 ″, 450 ′″ are described above.

[0084] The method 500 further includes step S503 of arranging the airfoils 118 adjacent to each other in a circumferential arrangement such that a portion of each hub 300 compresses a portion of an adjacent spring member 450, 450', 450", 450'" in a circumferential direction. The compressed spring members 450, 450', 450", 450'" apply a circumferential load to portions of adjacent hubs 300 to lock adjacent airfoils 118 together.

[0085] Fig.12 is a rear perspective view of three wheel hubs 300 and hub shield assemblies after assembly according to one or more embodiments, and Fig.13 is a front perspective view of three wheel hubs 300 and a hub shroud assembly after assembly according to one or more embodiments. Fig.14is a cross-sectional view of the assembled hub 300 and hub shroud assembly according to one or more embodiments. Fig.15 is a rear perspective view of a hub shield assembly according to one or more embodiments, wherein the hub 300 is removed, and Fig.16 is a front perspective view of a hub shroud assembly with the hub 300 removed, according to one or more embodiments.

[0086] Figure 12-14 The wheel hub 300 is similar to the one described above with respect to Figure 4-6 For example, Figure 12-14 Each hub 300 depicted in FIG. 1 includes a first radially extending member 320 and a second radially extending member 330 , each of which extends inwardly in a radial direction R from an inner surface of the hub 300 in a radial direction to form a space therebetween.

[0087] However, for Figure 12-14 In the embodiment, the first extension member 320 of each hub 300 includes an inclined portion 323 at its circumferential end (see Fig.13 ). When viewed from the longitudinal direction L, each inclined portion 323 is inclined so as to form an acute angle with a plane defined by the radial direction R and the longitudinal direction L.

[0088] In addition, the extension member 330 of each hub 300 includes an inclined portion 333 at its circumferential end (see Fig.12 ). When viewed in the longitudinal direction L, each inclined portion 333 is inclined so as to form an acute angle with a plane defined by the radial direction R and the longitudinal direction L. The extension member 330 of each hub 300 may further include another inclined portion 335 at a front longitudinal end of the extension member 330 (facing a space formed between the first radial extension member 320 and the second radial extension member 330). When viewed in the circumferential direction C, each inclined portion 335 is inclined so as to form an acute angle with a plane defined by the radial direction and the circumferential direction C.

[0089] Each hub 300 is disposed on the outer surface (in the radial direction R) of the interstage seal 410. According to one or more embodiments, the interstage seal 410 is an annular structure disposed on the outer surface of the seal 420 in the radial direction R. In one or more embodiments, the interstage seal 410 may be formed as segments that together form an annular structure. The seal 420 may be a honeycomb seal for forming an airflow seal having one or more teeth that rotate relative to the seal 420. Alternatively, the seal 420 may be any other suitable structure. The seal 420 may be attached to the interstage seal 410 in any suitable manner (e.g., welding), or may be formed integrally with the interstage seal 410.

[0090] The hub shroud assembly includes a first wedge-shaped structure 610 attached to the interstage seal 410 (see Fig.12 ) and a second wedge-shaped structure 620 (see Fig.13 ). The first wedge-shaped structure 610 and the second wedge-shaped structure 620 can be attached to the outer surface of the interstage seal 410, or formed integrally with the outer surface of the interstage seal 410. For example, the first wedge-shaped structure 610 and the second wedge-shaped structure 620 can be brazed to the interstage seal 410. The first wedge-shaped structure 610 is disposed at the rear of the second wedge-shaped structure 620 in the illustrated embodiment. As shown, the first wedge-shaped structure 610 and the second wedge-shaped structure 620 together with the interstage seal 410 can span multiple blades. Alternatively, each blade can have a separate first wedge-shaped structure 610 and second wedge-shaped structure 620.

[0091] Specific reference Fig.12 and 14 as well as Fig.15 , the first wedge-shaped structure 610 includes a first body 611 and a wedge-shaped portion 613 extending rearward from a rear surface of the first body 611 in a longitudinal direction L. Each wedge-shaped portion 613 defines a tip oriented outwardly in a radial direction R. The exemplary wedge-shaped portion 613 shown is triangular when viewed in the longitudinal direction L. The first wedge-shaped structure 610 further includes a hook portion 615 extending from an outer surface of the first body 611 in the radial direction R. The hook portion 615 is U-shaped and opens inwardly in the radial direction R.

[0092] The rear surface of the first body 611 may be inclined so as to abut and be flush with the inclined portion 335 of the extension member 330. This inclination may help position and align the hub 300 with the interstage seal 410. Fig.12 As shown, according to one or more embodiments, the inclined rear surface of the first body 611 may span two sections of the interstage seal 410 .

[0093] The radial outer surface of the wedge 613 abuts the inclined portion 333 at the circumferential end of the extension member 330. When the gas turbine engine 10 is not operating, the radial outer surface of the wedge 613 may be flush with the inclined portion 333. In addition, the wedge 613 may have a larger radial dimension than the inclined portion 333.

[0094] The retaining structure 630 may be an annular retaining ring formed as a single annular ring with a split or formed as segments that together form an annular ring. According to one or more embodiments, the retaining structure 630 is inserted into the inwardly facing hook 615 of the first wedge-shaped structure 610, and the inwardly facing hook 615 is hooked on the retaining structure 630. According to one or more embodiments, at least a portion of the radially outer surface and both longitudinal surfaces of the retaining structure 630 are in contact with the hook 615. The retaining structure 630 may be retained within the hook 615 so that there is a gap between the retaining structure 630 and the interstage seal 410. The retaining structure 630 may help retain each interstage seal 410 when the gas turbine engine 10 is not operating.

[0095] Now special reference Figure 13-14 as well as Fig.16 , the second wedge-shaped structure 620 includes a second body 621 and a wedge-shaped portion 623 extending outwardly from an outer surface of the second body 621 in a radial direction R. Each wedge-shaped portion 623 defines a tip oriented outwardly in the radial direction R. The exemplary wedge-shaped portion 623 shown is triangular when viewed in the longitudinal direction L. According to one or more embodiments, the wedge-shaped portion 613 of the first wedge-shaped structure 610 is aligned with the wedge-shaped portion 623 of the second wedge-shaped structure in the longitudinal direction.

[0096] The radial outer surface of the wedge 623 abuts the inclined portion 323 at the circumferential end of the extension member 320. When the gas turbine engine 10 is not operating, the radial outer surface of the wedge 623 may be flush with the inclined portion 323. In addition, the wedge 623 may have a larger radial dimension than the inclined portion 323.

[0097] During operation of the gas turbine engine 10, as the outer rotor airfoil 118 rotates in the circumferential direction C, the interstage seal 410 exerts an outward centrifugal force in the radial direction R on the first wedge structure 610 and the second wedge structure 620. This centrifugal force pushes the wedge portions 613, 623 into the inclined portions 333, 323 of the extension members 330, 320. According to one or more embodiments, the wedge portions 613, 623 may be compressed in the radial direction R, which in turn causes the wedge portions 613, 623 to expand in the circumferential direction, pressing against the inclined portions 333, 323. That is, the wedge portions 613, 623 exert a circumferential force on the corresponding inclined portions 333, 323 to press each of the extension members 330, 320 toward the adjacent extension members 330, 320, which locks the extension members 330, 320 and their corresponding hubs 300 together in the circumferential direction C.

[0098] Fig.17A flow chart of a method 700 of assembling an airfoil assembly for a turbine engine according to one or more embodiments is shown. The method 700 includes step S701 of forming a plurality of airfoils 118, each airfoil having a hub 300 with a pair of extension members 320, 330. According to one or more embodiments, the pair of extension members 320, 330 may be a first radially extending member 320 and a second radially extending member 330 formed as radial walls. Different embodiments of airfoils 118, hubs 300, and extension members 320, 330 that may be formed are described above.

[0099] The method 700 further includes step S702 of attaching the first wedge-shaped structure 610 and the second wedge-shaped structure 620 to the outer surface of the interstage seal 410. For example, the first wedge-shaped structure 610 and the second wedge-shaped structure 620 may be brazed to the outer surface of the interstage seal 410. Alternatively, the first wedge-shaped structure 610 and the second wedge-shaped structure 620 may be integrally formed with the outer surface of the interstage seal 410.

[0100] The method 700 further includes step S703 of inserting the first wedge structure 610 and the second wedge structure 620 into the space defined between the pair of extension members 320, 330 of each airfoil 118. Details of the first wedge structure 610 and the second wedge structure 620 and the retaining structure 630 are as described above.

[0101] The method 700 further includes step S704 of arranging the airfoils 118 adjacent to each other in a circumferential arrangement such that the wedge portions 613 , 623 of the first wedge structure 610 and the second wedge structure 620 abut against the inclined portions 333 , 323 of the corresponding extension members 330 , 320 .

[0102] The method 700 further includes step S705 of inserting the retaining structure 630 through the hook portion 615 of the first wedge-shaped structure 610. Once inserted, the retaining structure 630 is retained by the hook portion 615.

[0103] The method 700 further includes step S706 of rotating the airfoil 118 so that the centrifugal force in the radial direction R pushes the wedges 613 , 623 into the inclined portions 333 , 323 of the extension members 330 , 320 , which in turn applies a circumferential force to the inclined portions 333 , 323 of the extension members 330 , 320 .

[0104] This written description uses examples to disclose aspects of the invention, including the best mode, and also enables those skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. If these other examples include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims, such other examples are intended to be within the scope of the claims.

[0105] The following topics provide further aspects:

[0106] A turbine engine airfoil assembly, the turbine engine defining an axial direction, a radial direction, and a circumferential direction, the airfoil assembly comprising: a first airfoil, the first airfoil defining a first end in the radial direction; a first hub, the first hub being disposed at the first end of the first airfoil and comprising a first extension member extending at least partially in the radial direction; a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end in the radial direction; a second hub, the second hub being disposed at the first end of the second airfoil and comprising a second extension member extending at least partially in the radial direction; and a circumferential offset assembly, the circumferential offset assembly being operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both.

[0107] The airfoil assembly according to one or more of these clauses, wherein the circumferential biasing assembly is a first shroud assembly, and wherein the first shroud assembly includes a first spring member coupled to, positioned adjacent to, or both the first extension member.

[0108] The airfoil assembly according to one or more of these clauses, further comprising: a second circumferential biasing assembly, the second circumferential biasing assembly configured as a second shroud assembly, wherein the second shroud assembly includes a second spring member, the second spring member is coupled to the second extension member, is positioned adjacent to the second extension member, or both, and wherein the first spring member is configured to apply a circumferential load to the second hub.

[0109] The airfoil assembly according to one or more of these clauses, wherein the first hub and the second hub are torsion springs, and wherein the first hub exerts a torsion force on the second hub.

[0110] The airfoil assembly according to one or more of these clauses further comprises: a plurality of adjacent airfoils other than the first and second airfoils, wherein the plurality of adjacent airfoils comprises a third airfoil and a fourth airfoil, the third airfoil being at one end of the plurality of adjacent airfoils and the fourth airfoil being at another end of the plurality of adjacent airfoils, wherein the third airfoil is adjacent to the second airfoil and the second spring member of the second airfoil applies a circumferential load on a third hub disposed on the third airfoil, and wherein the fourth airfoil is adjacent to the first airfoil and the fourth spring member of the fourth airfoil applies a circumferential load on the first hub.

[0111] An airfoil assembly according to one or more of these clauses, wherein the first extension member is part of a first pair of extension members, the first pair of extension members being spaced apart in an axial direction to define a first space therebetween, and wherein the first shroud assembly is disposed in the first space between the first pair of extension members.

[0112] The airfoil assembly according to one or more of these clauses further comprises: a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end in a radial direction; a second hub, the second hub being disposed at the first end of the second airfoil and comprising a second pair of extension members extending at least partially in a radial direction, the second pair of extension members being spaced apart in an axial direction to define a second space therebetween; and a second circumferential biasing assembly, the second circumferential biasing assembly being configured as a second shroud assembly, wherein the second shroud assembly comprises a second spring member disposed in a second space between the second pair of extension members, and wherein the first spring member is configured to apply a circumferential load to the second hub.

[0113] The airfoil assembly according to one or more of these clauses, wherein the second hub includes an axial wall extending in an axial direction from one of the second pair of extension members, and wherein the first spring member applies a circumferential load on the axial wall.

[0114] The airfoil assembly according to one or more of these clauses, wherein the second spring member is attached to the other of the second pair of extension members.

[0115] The airfoil assembly according to one or more of these clauses, wherein the first shroud assembly further comprises a sealing element coupled to or formed with the first spring member.

[0116] The airfoil assembly according to one or more of these clauses, wherein the first spring member is a leaf metal spring.

[0117] The airfoil assembly according to one or more of these clauses, wherein the first end of the first airfoil on which the first hub is disposed is an inner end in a radial direction.

[0118] The airfoil assembly according to one or more of these clauses, wherein the circumferential offset assembly includes a circumferential offset block positioned at least partially between the first extension member of the first hub and the second extension member of the second hub.

[0119] The airfoil assembly according to one or more of these clauses, wherein the circumferential offset block includes a wedge-shaped portion defining a tip oriented outwardly in a radial direction.

[0120] The airfoil assembly according to one or more of these clauses, wherein the first extension member and the second extension member each define an inclined surface, and wherein the wedge-shaped portion is positioned between the inclined surfaces of the first extension member and the second extension member in a circumferential direction.

[0121] An airfoil assembly according to one or more of these clauses, wherein the circumferential offset block includes a wedge-shaped portion and a hook portion at least partially positioned between a first extension member of the first hub and a second extension member of the second hub, and wherein the circumferential offset assembly further includes a retaining member at least partially positioned in a channel formed by the hook portion.

[0122] The airfoil assembly according to one or more of these clauses, wherein each of the first hub and the second hub comprises a ceramic matrix composite material.

[0123] A turbine engine defining an axial direction, a radial direction, and a circumferential direction, comprising: a compressor section; a combustion section; and a turbine section, wherein the compressor section or the turbine section comprises an airfoil assembly, the airfoil assembly comprising: a first airfoil, the first airfoil defining a first end in a radial direction; a first hub, the first hub being disposed at a first end of the first airfoil and comprising a first extension member extending at least partially in a radial direction; a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end in a radial direction; a second hub, the second hub being disposed at a first end of the second airfoil and comprising a second extension member extending at least partially in a radial direction; and a circumferential offset assembly, the circumferential offset assembly being operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both.

[0124] The turbine engine according to one or more of these clauses, wherein the circumferential offset assembly is a first shroud assembly, and wherein the first shroud assembly includes a spring member coupled to, positioned adjacent to, or both of the first extension member.

[0125] The turbine engine according to one or more of these clauses, wherein the circumferential offset assembly includes a circumferential offset block positioned at least partially between the first extension member of the first hub and the second extension member of the second hub.

Claims

1. An airfoil assembly for a turbine engine, characterized in that: The turbine engine defines an axial direction, a radial direction, and a circumferential direction, and the airfoil assembly includes: a first airfoil defining a first end along the radial direction; a first hub disposed at the first end of the first airfoil and including a first extension member extending at least partially in the radial direction; a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end along the radial direction; a second hub disposed at the first end of the second airfoil and including a second extension member extending at least partially in the radial direction; and a circumferential biasing assembly operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both; wherein the circumferential biasing assembly is a first shroud assembly, and wherein the first shroud assembly includes a first spring member coupled to the first extension member, positioned adjacent to the first extension member, or both; wherein the first extension member is part of a first pair of extension members, the first pair of extension members being spaced apart in the axial direction to define a first space therebetween, and Wherein, the first shield assembly is disposed in the first space between the first pair of extension members.

2. The airfoil assembly according to claim 1, wherein: Further including: a second circumferentially offset assembly, the second circumferentially offset assembly being configured as a second shroud assembly, wherein the second shield assembly includes a second spring member coupled to the second extension member, positioned adjacent to the second extension member, or both, and The first spring member is configured to apply a circumferential load to the second hub.

3. The airfoil assembly according to claim 2, wherein: wherein the first hub and the second hub are torsion springs, and The first hub applies a torque to the second hub.

4. The airfoil assembly according to claim 2, wherein: Further including: a plurality of adjacent airfoils other than the first airfoil and the second airfoil, wherein the plurality of adjacent airfoils include a third airfoil and a fourth airfoil, the third airfoil being at one end of the plurality of adjacent airfoils, and the fourth airfoil being at the other end of the plurality of adjacent airfoils, wherein the third airfoil is adjacent to the second airfoil, and a second spring member of the second airfoil applies a circumferential load to a third hub disposed on the third airfoil, and The fourth airfoil is adjacent to the first airfoil, and a fourth spring member of the fourth airfoil applies a circumferential load on the first hub.

5. The airfoil assembly according to claim 1, wherein: Further including: a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end along the radial direction; a second hub disposed at the first end of the second airfoil and including a second pair of extension members extending at least partially in the radial direction, the second pair of extension members being spaced apart in the axial direction to define a second space therebetween; as well as a second circumferentially offset assembly, the second circumferentially offset assembly being configured as a second shroud assembly, wherein the second shield assembly includes a second spring member disposed in the second space between the second pair of extension members, and Wherein, the first spring member is configured to apply a circumferential load to the second hub.

6. The airfoil assembly according to claim 5, characterized in that wherein the second hub comprises an axial wall extending in the axial direction from one of the second pair of extension members, and Wherein, the first spring member applies a circumferential load on the axial wall.

7. The airfoil assembly according to claim 6, wherein: in, The second spring member is attached to the other of the second pair of extension members.

8. The airfoil assembly according to claim 1, wherein: in, The first shield assembly further includes a sealing element coupled to or formed with the first spring member.

9. The airfoil assembly according to claim 1, wherein: in, The first spring member is a metal leaf spring.

10. The airfoil assembly according to claim 1, wherein: in, The first end of the first airfoil on which the first hub is disposed is an inner end in the radial direction.

11. The airfoil assembly according to claim 1, wherein: in, The circumferential offset assembly includes a circumferential offset block at least partially positioned between the first extension member of the first hub and the second extension member of the second hub.

12. The airfoil assembly according to claim 11, wherein: in, The circumferential offset block includes a wedge-shaped portion defining a tip oriented outwardly in the radial direction.

13. The airfoil assembly according to claim 12, wherein: wherein the first extension member and the second extension member each define an inclined surface, and wherein the wedge-shaped portion is positioned between the inclined surfaces of the first extension member and the second extension member along the circumferential direction.

14. The airfoil assembly according to claim 12, wherein: in, The circumferential offset block includes a wedge-shaped portion and a hook portion positioned at least partially between the first extension member of the first hub and the second extension member of the second hub, and Wherein, the circumferential biasing assembly further includes a retaining member at least partially positioned in the channel formed by the hook portion.

15. The airfoil assembly of claim 1, wherein: Each of the first hub and the second hub comprises a ceramic matrix composite material.

16. A turbine engine defining an axial direction, a radial direction and a circumferential direction, characterized in that: include: compressor section; Combustion section; and Turbine section, Wherein the compressor section or the turbine section comprises an airfoil assembly, the airfoil assembly comprising: a first airfoil defining a first end along the radial direction; a first hub disposed at the first end of the first airfoil and including a first extension member extending at least partially in the radial direction; a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end along the radial direction; a second hub disposed at the first end of the second airfoil and including a second extension member extending at least partially in the radial direction; and a circumferential biasing assembly operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both, wherein the circumferential biasing assembly is a first shroud assembly, and wherein the first shroud assembly includes a first spring member coupled to the first extension member, positioned adjacent to the first extension member, or both; wherein the first extension member is part of a first pair of extension members, the first pair of extension members being spaced apart in the axial direction to define a first space therebetween, and Wherein, the first shield assembly is disposed in the first space between the first pair of extension members.

17. The turbine engine according to claim 16, characterized in that wherein the circumferentially offset assembly is a first shroud assembly, and Wherein, the first shield assembly includes a spring member coupled to the first extension member, positioned adjacent to the first extension member, or both.

18. The turbine engine according to claim 16, characterized in that in, The circumferential offset assembly includes a circumferential offset block at least partially positioned between the first extension member of the first hub and the second extension member of the second hub.

19. An airfoil assembly for a turbine engine, characterized in that: The turbine engine defines an axial direction, a radial direction, and a circumferential direction, and the airfoil assembly includes: a first airfoil defining a first end along the radial direction; a first hub disposed at the first end of the first airfoil and including a first extension member extending at least partially in the radial direction; a second airfoil, the second airfoil being adjacent to the first airfoil, the second airfoil defining a first end along the radial direction; a second hub disposed at the first end of the second airfoil and including a second extension member extending at least partially in the radial direction; and a circumferential biasing assembly operable with the first extension member, the second extension member, or both, for applying a circumferential force on the first extension member, the second extension member, or both; wherein the circumferential biasing assembly is a first shroud assembly, and wherein the first shroud assembly includes a first spring member coupled to the first extension member, positioned adjacent to the first extension member, or both; a second circumferentially offset assembly, the second circumferentially offset assembly being configured as a second shroud assembly, wherein the second shield assembly includes a second spring member coupled to the second extension member, positioned adjacent to the second extension member, or both, and The first spring member is configured to apply a circumferential load to the second hub.

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