AIRFOIL ASSEMBLY WITH A TRUNNION AND SPAR

An airfoil assembly having a trunnion and a spar. The trunnion having an interior surface defining a flared socket with an open top. The spar extending from the flared socket and through the open top. The spar further having a furcated tail with a set of branches defining an intervening gap between adjacent branches of the set of branches

TECHNICAL FIELD

The disclosure generally relates to an airfoil assembly, and more specifically to an airfoil assembly having a trunnion and a spar.

BACKGROUND

Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of gases passing through a fan with a plurality of fan blades, then into the engine through a series of compressor stages, which include pairs of rotating blades and stationary vanes, through a combustor, and then through a series of turbine stages, which include pairs of rotating blades and stationary vanes. The blades are mounted to rotating disks, while the vanes are mounted to stator disks.

During operation air is brought into the compressor section through the fan section where it is then pressurized in the compressor and mixed with fuel in the combustor for generating hot combustion gases which flow downstream through the turbine stages where the air is expanded and exhausted out an exhaust section. The expansion of the air in the turbine section is used to drive the rotating sections of the fan section and the compressor section. The drawing in of air, the pressurization of the air, and the expansion of the air is done, in part, through rotation of various rotating blades mounted to respective disks throughout the fan section, the compressor section and the turbine section, respectively. The rotation of the rotating blades imparts mechanical stresses along various portions of the blade; specifically, where the blade is mounted to the disk.

In some turbine engines, a variable pitch airfoil can be included, which can be selectively rotated to adjust or otherwise tailor the flow of fluid over the variable pitch airfoil. The variable pitch airfoil is movable through use of a trunnion and a spar. The trunnion can rotate about a rotational axis, which in turn rotates the spar and the variable pitch airfoil. The trunnion is coupled to or otherwise formed with the spar.

DETAILED DESCRIPTION

Aspects of the disclosure herein are directed to an airfoil assembly for a turbine engine. The airfoil assembly includes an airfoil, a spar, and a trunnion. The spar couples the airfoil to the trunnion. The spar includes a furcated tail with a set of branches that define an intervening gap. A wedge is received within the intervening gap.

The airfoil assembly, specifically the spar, is retained within the trunnion through the wedge. For purposes of illustration, the present disclosure will be described with respect to an airfoil assembly for a turbine engine, specifically a fan blade of the turbine engine. It will be understood, however, that aspects of the disclosure described herein are not so limited and can have general applicability within other engines or within other portions of the turbine engine. For example, the disclosure can have applicability for an airfoil assembly in other engines or vehicles, and can be used to provide benefits in industrial, commercial, and residential applications.

As used herein, the term “upstream” refers to a direction that is opposite the fluid flow direction, and the term “downstream” refers to a direction that is in the same direction as the fluid flow. The term “fore” or “forward” means in front of something and “aft” or “rearward” means behind something. For example, when used in terms of fluid flow, fore/forward can mean upstream and aft/rearward can mean downstream.

Additionally, as used herein, the terms “radial” or “radially” refer to a direction away from a common center. For example, in the overall context of a turbine engine, radial refers to a direction along a ray extending between a center longitudinal axis of the engine and an outer engine circumference. Furthermore, as used herein, the term “set” or a “set” of elements can be any number of elements, including only one.

Further yet, as used herein, the term “fluid” or iterations thereof can refer to any suitable fluid within the gas turbine engine at least a portion of the gas turbine engine is exposed to such as, but not limited to, combustion gases, ambient air, pressurized airflow, working airflow, or any combination thereof. It is yet further contemplated that the gas turbine engine can be other suitable turbine engine such as, but not limited to, a steam turbine engine or a supercritical carbon dioxide turbine engine. As a non-limiting example, the term “fluid” can refer to steam in a steam turbine engine, or to carbon dioxide in a supercritical carbon dioxide turbine engine.

The term “composite,” as used herein is, is indicative of a component having two or more materials. A composite can be a combination of at least two or more metallic, non-metallic, or a combination of metallic and non-metallic elements or materials. Examples of a composite material can be, but not limited to, a polymer matrix composite (PMC), a ceramic matrix composite (CMC), a metal matrix composite (MMC), carbon fibers, a polymeric resin, a thermoplastic resin, bismaleimide (BMI) materials, polyimide materials, an epoxy resin, glass fibers, and silicon matrix materials.

As used herein, a “composite” component refers to a structure or a component including any suitable composite material. Composite components, such as a composite airfoil, can include several layers or plies of composite material. The layers or plies can vary in stiffness, material, and dimension to achieve the desired composite component or composite portion of a component having a predetermined weight, size, stiffness, and strength.

One or more layers of adhesive can be used in forming or coupling composite components. Adhesives can include resin and phenolics, wherein the adhesive can require curing at elevated temperatures or other hardening techniques.

As used herein, PMC refers to a class of materials. By way of example, the PMC material is defined in part by a prepreg, which is a reinforcement material pre-impregnated with a polymer matrix material, such as thermoplastic resin. Non-limiting examples of processes for producing thermoplastic prepregs include hot melt pre-pregging in which the fiber reinforcement material is drawn through a molten bath of resin and powder pre-pregging in which a resin is deposited onto the fiber reinforcement material, by way of non-limiting example electrostatically, and then adhered to the fiber, by way of non-limiting example, in an oven or with the assistance of heated rollers. The prepregs can be in the form of unidirectional tapes or woven fabrics, which are then stacked on top of one another to create the number of stacked composite plies desired for the part.

Multiple layers of prepreg are stacked to the proper thickness and orientation for the composite component and then the resin is cured and solidified to render a fiber reinforced composite part. Resins for matrix materials of PMCs can be generally classified as thermosets or thermoplastics. Thermoplastic resins are generally categorized as polymers that can be repeatedly softened and flowed when heated and hardened when sufficiently cooled due to physical rather than chemical changes. Notable example classes of thermoplastic resins include nylons, thermoplastic polyesters, polyaryletherketones, and polycarbonate resins. Specific example of high-performance thermoplastic resins that have been contemplated for use in aerospace applications include, polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyaryletherketone (PAEK), and polyphenylene sulfide (PPS). In contrast, once fully cured into a hard rigid solid, thermoset resins do not undergo significant softening when heated, but instead thermally decompose when sufficiently heated. Notable examples of thermoset resins include epoxy, bismaleimide (BMI), and polyimide resins.

Instead of using a prepreg, in another non-limiting example, with the use of thermoplastic polymers, it is possible to utilize a woven fabric. Woven fabric can include, but is not limited to, dry carbon fibers woven together with thermoplastic polymer fibers or filaments. Non-prepreg braided architectures can be made in a similar fashion. With this approach, it is possible to tailor the fiber volume of the part by dictating the relative concentrations of the thermoplastic fibers and reinforcement fibers that have been woven or braided together. Additionally, different types of reinforcement fibers can be braided or woven together in various concentrations to tailor the properties of the part. For example, glass fibers, carbon fibers, and thermoplastic fibers could all be woven together in various concentrations to tailor the properties of the part. The carbon fibers provide the strength of the system, the glass fibers can be incorporated to enhance the impact properties, which is a design characteristic for parts located near the inlet of the engine, and the thermoplastic fibers provide the binding for the reinforcement fibers.

In yet another non-limiting example, resin transfer molding (RTM) can be used to form at least a portion of a composite component. Generally, RTM includes the application of dry fibers or matrix material to a mold or cavity. The dry fibers or matrix material can include prepreg, braided material, woven material, or any combination thereof.

Resin can be pumped into or otherwise provided to the mold or cavity to impregnate the dry fibers or matrix material. The combination of the impregnated fibers or matrix material and the resin are then cured and removed from the mold. When removed from the mold, the composite component can require post-curing processing.

It is contemplated that RTM can be a vacuum assisted process. That is, the air from the cavity or mold can be removed and replaced by the resin prior to heating or curing. It is further contemplated that the placement of the dry fibers or matrix material can be manual or automated.

The dry fibers or matrix material can be contoured to shape the composite component or direct the resin. Optionally, additional layers or reinforcing layers of a material differing from the dry fiber or matrix material can also be included or added prior to heating or curing.

As used herein, CMC refers to a class of materials with reinforcing fibers in a ceramic matrix. Generally, the reinforcing fibers provide structural integrity to the ceramic matrix. Some examples of reinforcing fibers can include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), non-oxide carbon-based materials (e.g., carbon), oxide ceramics (e.g., silicon oxycarbides, silicon oxynitrides, aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminosilicates such as mullite, or mixtures thereof), or mixtures thereof.

Some examples of ceramic matrix materials can include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), oxide ceramics (e.g., silicon oxycarbides, silicon oxynitrides, aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminosilicates, or mixtures thereof), or mixtures thereof. Optionally, ceramic particles (e.g., oxides of Si, Al, Zr, Y, and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite, and montmorillonite) can also be included within the ceramic matrix.

Generally, particular CMCs can be referred to as their combination of type of fiber/type of matrix. For example, C/SiC for carbon-fiber-reinforced silicon carbide; SiC/SiC for silicon carbide-fiber-reinforced silicon carbide, SiC/SiN for silicon carbide fiber-reinforced silicon nitride; SiC/SiC—SiN for silicon carbide fiber-reinforced silicon carbide/silicon nitride matrix mixture, etc. In other examples, the CMCs can be comprised of a matrix and reinforcing fibers comprising oxide-based materials such as aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminosilicates, and mixtures thereof. Aluminosilicates can include crystalline materials such as mullite (3Al2O3·2SiO2), as well as glassy aluminosilicates.

In certain non-limiting examples, the reinforcing fibers may be bundled and/or coated prior to inclusion within the matrix. For example, bundles of the fibers may be formed as a reinforced tape, such as a unidirectional reinforced tape. A plurality of the tapes may be laid up together to form a preform component. The bundles of fibers may be impregnated with a slurry composition prior to forming the preform or after formation of the preform. The preform may then undergo thermal processing, and subsequent chemical processing to arrive at a component formed of a CMC material having a desired chemical composition. For example, the preform may undergo a cure or burn-out to yield a high char residue in the preform, and subsequent melt-infiltration with silicon, or a cure or pyrolysis to yield a silicon carbide matrix in the preform, and subsequent chemical vapor infiltration with silicon carbide. Additional steps may be taken to improve densification of the preform, either before or after chemical vapor infiltration, by injecting it with a liquid resin or polymer followed by a thermal processing step to fill the voids with silicon carbide. CMC material as used herein may be formed using any known or hereinafter developed methods including but not limited to melt infiltration, chemical vapor infiltration, polymer impregnation pyrolysis (PIP), or any combination thereof.

Such materials, along with certain monolithic ceramics (i.e., ceramic materials without a reinforcing material), are particularly suitable for higher temperature applications. Additionally, these ceramic materials are lightweight compared to superalloys, yet can still provide strength and durability to the component made therefrom. Therefore, such materials are currently being considered for many gas turbine components used in higher temperature sections of gas turbine engines, such as airfoils (e.g., turbines, and vanes), combustors, shrouds and other like components, that would benefit from the lighter-weight and higher temperature capability these materials can offer.

The term “metallic” as used herein is indicative of a material that includes metal such as, but not limited to, titanium, iron, aluminum, stainless steel, and nickel alloys. A metallic material or alloy can be a combination of at least two or more elements or materials, where at least one is a metal.

FIG.1is a schematic cross-sectional diagram of a turbine engine10for an aircraft. The turbine engine10has a generally longitudinally extending axis or centerline12extending forward14to aft16. The turbine engine10includes, in downstream serial flow relationship, a fan section18including a fan20, a compressor section22including a booster or low pressure (LP) compressor24and a high pressure (HP) compressor26, a combustion section28including a combustor30, a turbine section32including an HP turbine34, and an LP turbine36, and an exhaust section38.

The fan section18includes a fan casing40surrounding the fan20. The fan20includes a plurality of fan blades42disposed radially about the engine centerline12. The HP compressor26, the combustor30, and the HP turbine34form an engine core44of the turbine engine10, which generates combustion gases. The engine core44is surrounded by a core casing46, which can be coupled with the fan casing40.

An HP shaft or spool48disposed coaxially about the engine centerline12of the turbine engine10drivingly connects the HP turbine34to the HP compressor26. An LP shaft or spool50, which is disposed coaxially about the engine centerline12of the turbine engine10within the larger diameter annular HP spool48, drivingly connects the LP turbine36to the LP compressor24and fan20. The spools48,50are rotatable about the engine centerline and couple to a plurality of rotatable elements, which can collectively define a rotor51.

The LP compressor24and the HP compressor26respectively include a plurality of compressor stages52,54, in which a set of compressor blades56,58rotate relative to a corresponding set of static compressor vanes60,62to compress or pressurize the stream of fluid passing through the stage. In a single compressor stage52,54, multiple compressor blades56,58can be provided in a ring and can extend radially outward relative to the engine centerline12, from a blade platform to a blade tip, while the corresponding static compressor vanes60,62are positioned upstream of and adjacent to the rotating compressor blades56,58. It is noted that the number of blades, vanes, and compressor stages shown inFIG.1were selected for illustrative purposes only, and that other numbers are possible.

The compressor blades56,58for a stage of the compressor can be mounted to (or integral to) a disk61, which is mounted to the corresponding one of the HP and LP spools48,50. The static compressor vanes60,62for a stage of the compressor can be mounted to the core casing46in a circumferential arrangement.

The HP turbine34and the LP turbine36respectively include a plurality of turbine stages64,66, in which a set of turbine blades68,70are rotated relative to a corresponding set of static turbine vanes72,74, also referred to as a nozzle, to extract energy from the stream of fluid passing through the stage. In a single turbine stage64,66, multiple turbine blades68,70can be provided in a ring and can extend radially outward relative to the engine centerline12while the corresponding static turbine vanes72,74are positioned upstream of and adjacent to the rotating turbine blades68,70. It is noted that the number of blades, vanes, and turbine stages shown inFIG.1were selected for illustrative purposes only, and that other numbers are possible.

The turbine blades68,70for a stage of the turbine can be mounted to a disk71, which is mounted to the corresponding one of the HP and LP spools48,50. The turbine vanes72,74for a stage of the compressor can be mounted to the core casing46in a circumferential arrangement.

Complementary to the rotor portion, the stationary portions of the turbine engine10, such as the static vanes60,62,72,74among the compressor and turbine sections22,32are also referred to individually or collectively as a stator63. As such, the stator63can refer to the combination of non-rotating elements throughout the turbine engine10.

In operation, the airflow exiting the fan section18is split such that a portion of the airflow is channeled into the LP compressor24, which then supplies a pressurized airflow76to the HP compressor26, which further pressurizes the air. The pressurized airflow76from the HP compressor26is mixed with fuel in the combustor30and ignited, thereby generating combustion gases. Some work is extracted from these gases by the HP turbine34, which drives the HP compressor26. The combustion gases are discharged into the LP turbine36, which extracts additional work to drive the LP compressor24, and the exhaust gas is ultimately discharged from the turbine engine10via the exhaust section38. The driving of the LP turbine36drives the LP spool50to rotate the fan20and the LP compressor24.

A portion of the pressurized airflow76can be drawn from the compressor section22as bleed air77. The bleed air77can be drawn from the pressurized airflow76and provided to engine components requiring cooling. The temperature of pressurized airflow76entering the combustor30is significantly increased above the bleed air temperature. The bleed air77may be used to reduce the temperature of the core components downstream of the combustor30. The bleed air77can also be utilized by other systems.

A remaining portion of the airflow, referred to as a bypass airflow78, bypasses the LP compressor24and engine core44and exits the turbine engine10through a stationary vane row, and more particularly an outlet guide vane assembly80, comprising a plurality of airfoil guide vanes82, at a fan exhaust side84. More specifically, a circumferential row of radially extending airfoil guide vanes82are utilized adjacent the fan section18to exert some directional control of the bypass airflow78.

Some of the air supplied by the fan20can bypass the engine core44and be used for cooling of portions, especially hot portions, of the turbine engine10, and/or used to cool or power other aspects of the aircraft. In the context of a turbine engine, the hot portions of the engine are normally downstream of the combustor30, especially the turbine section32, with the HP turbine34being the hottest portion as it is directly downstream of the combustion section28. Other sources of cooling fluid can be, but are not limited to, fluid discharged from the LP compressor24or the HP compressor26.

FIG.2is schematic illustration of an airfoil assembly130suitable for use within the turbine engine10ofFIG.1. The airfoil assembly130can include an airfoil132that is any suitable airfoil of the turbine engine10. As a non-limiting example, the airfoil132can be a blade of the plurality of fan blades42, or a blade from the compressor blades56,58or the turbine blades68,70. It is contemplated that the airfoil132can be a blade, vane, airfoil, or other component of any turbine engine, such as, but not limited to, a gas turbine engine, a turboprop engine, a turboshaft engine, a ducted turbofan engine, an unducted turbofan engine or an open rotor turbine engine.

The airfoil132can include a wall138bounding an interior148. The wall138can extend between a leading edge144and a trailing edge146to define a chordwise direction (C). The wall138can further extend between a root140and a tip142to define a spanwise direction (S). The wall138can be a composite wall made of one or more layers of composite material. The one or more layers of material can be applied during the same stage or different stages of the manufacturing of the airfoil132.

By way of non-limiting example, wall138can include at least a polymer matrix composite (PMC) portion or a polymeric portion. The polymer matrix composite can include, but is not limited to, a matrix of thermoset (epoxies, phenolics) or thermoplastic (polycarbonate, polyvinylchloride, nylon, acrylics) and embedded glass, carbon, steel, or Kevlar fibers.

The airfoil assembly130can further include a spar136and a trunnion134. The spar136can extend into the interior148. The spar136can extend from the root140. The spar136can be operably coupled to the trunnion134. The spar136can be any suitable material such as, but not limited to, a composite material. The spar136can be a metal composite. The trunnion134can include any suitable material such as, but no limited to, a metallic material or a composite material. It will be appreciated that the term composite material can further include metals but with a composite architecture (e.g., a metal matrix composite). In the case of a composite material, the spar136and/or the trunnion134can be any suitable composite material such as a 2D or 3D composite, a laminate skin, a woven or a braided composite, or any other suitable composite.

The airfoil132has a span length (L) measured along the spanwise direction S from the root140at 0% the span length (L) to the tip142at 100% the span length (L). An entirety of the spar136can be located below 20% of the span length (L). Alternatively, the spar136can extend past 20% of the span length (L).

During operation of the airfoil assembly130, the trunnion134can rotate about a pitch axis (Pax) in a rotational direction (Rd). As the spar136couples the trunnion134to the airfoil132, rotation of the trunnion134in the rotational direction (Rd) causes the airfoil132to rotate about the pitch axis (Pax). This rotation can be used to control the pitch of the airfoil assembly130such that the airfoil assembly130is defined as a variable pitch airfoil assembly. The pitch of the airfoil assembly130can be varied based on the operation or intended operation of the turbine engine (e.g., the turbine engine10ofFIG.1) that the airfoil assembly130is provided on.

FIG.3is a schematic cross-sectional view of the airfoil assembly130as seen from sectional line III-III ofFIG.2. The airfoil132(FIG.2) is removed from the airfoil assembly130for illustrative purposes.

The trunnion134includes a wall163with an interior surface162at least a partially defining a flared socket164of the trunnion134. The flared socket164extends between an open top170and a bottom168. The spar136extends through the open top170and into the interior148. The bottom168can be an open bottom or a sealed/closed off bottom. The flared socket164can take any suitable shape with at least one flared cross section, as illustrated.

The spar extends along a centerline axis150and terminates at a first end160within the flared socket164. The spar136includes a furcated tail152with a set of branches. As a non-limiting example, the set of branches include a first branch154and a second branch156that define an intervening gap158therebetween. The intervening gap158extends axially into the spar136and terminates at an apex159. A width of the first branch154and the second branch156varies along the axial extent of furcated tail152. As a non-limiting example, each branch of the set of branches includes a maximum width (W1) and a minimum width (W2) defined as the maximum and minimum radial distances, respectively, between the intervening gap158and a radially outward portion of the furcated tail152from the intervening gap158. The maximum width (W1) can be provided axially nearer the first end160than the minimum width (W2). As a non-limiting example, the maximum width (W1) can be provided at the first end160while the minimum width (W2) can be provided axially nearest the apex159. The spar136can be symmetric or asymmetric about the centerline axis150.

A wedge172can be received within the intervening gap158. The wedge172can be held in place within the intervening gap158through frictional contact. Alternatively, the wedge172can be coupled to the spar136through any suitable coupling method such as, but not limited to, bonding, curing, welding, adhesion, fastening, or the like. The wedge172can be any suitable material. As a non-limiting example, the wedge172can include a metallic material or a composite material. As a non-limiting example, the airfoil assembly130can include the spar136including a composite material, the trunnion134including a metallic material and the wedge172including a metallic material. The wedge172, as illustrated, is a solid body. However, it will be appreciated that an interior of the wedge172or at least a portion of the wedge172can be hollow.

The wedge172is used to retain the spar136within the trunnion134. When received within the intervening gap158, the wedge172pushes the spar136, specifically the furcated tail152radially outward, with respect to the centerline axis150, such that the spar136is held in contact against the interior surface162of the trunnion134. While a gap is illustrated between the wedge172and the spar136, it will be appreciated that the wedge172can be sized to fill an entirety of the intervening gap158.

FIG.4is a schematic perspective, exploded view of the airfoil assembly130ofFIG.3. As illustrated, the spar136, and the wedge172can be polygonal (e.g., non-circular). As a non-liming example, the spar136and the wedge172can each include a rectangular cross section when cut along a horizontal plane that is perpendicular to the centerline axis150. The open top170can have a corresponding cross section to the spar136. As a non-limiting example, the open top170can have a rectangular cross section when viewed along the horizontal plane. The rectangular cross section can be provided along an entirety of the flared socket164(FIG.3).

It is contemplated that providing a trunnion134with the top opening170having a corresponding cross section to the cross section of the spar136is advantageous as there is a smooth transition between the spar136and the trunnion134. This, in turn, increases the total number of points of contact between the trunnion134and the spar136, meaning that the spar136will not move, rock or shake undesirably within the trunnion134.

FIG.5is a schematic cross-sectional view of an exemplary airfoil230suitable for use as the airfoil assembly130ofFIG.3. The airfoil assembly230is similar to the airfoil assembly130; therefore, like parts will be identified with like numerals increased to the200series with it being understood that description of the airfoil assembly130applies to the airfoil assembly230unless noted otherwise.

The airfoil assembly230includes a trunnion234and a spar236. The trunnion234includes a wall263defining an interior surface262at least partially defining a flared socket264that extends between an open top270and a bottom268. The spar236extends along a centerline axis250and terminates within the flared socket264at a first end260. The spar236includes a furcated tail252with at least a first branch254and a second branch256. An intervening gap258is defined between the first branch254and the second branch256. A wedge272can be received within the intervening gap258.

The airfoil assembly230is similar to the airfoil assembly130in that it uses the wedge272to retain the spar236within the trunnion234. The airfoil assembly230, however, further includes a retention block274within the flared socket264that confronts the first end260and the wedge272. The retention block274is provided inwardly from the furcated tail152in the spanwise direction(S) (FIG.3). The retention block274pushes against at least the wedge272and the furcated tail252to retain the wedge272within the intervening gap258. The retention block274can be secured within the flared socket264through any suitable method. As a non-limiting example, at least a portion of the interior surface262can include a threaded section and the retention block274can include an opposing thread such that the retention block274can be threaded into the trunnion234. Alternatively, the retention block274can be held in place through frictional contact or other coupling methods such as, but not limited to, bonding, adhesion, welding, or fastening. The retention block274can be provided along any suitable portion of the airfoil assembly230. As a non-limiting example, the retention block274can be sized to fit over the bottom268of the trunnion234. It is contemplated that the bottom268can include a threaded section such that the retention block274can be threaded over or otherwise into the bottom268and essentially act as a cap provided at the bottom268of the trunnion234.

The retention block274can be coupled to the trunnion234and/or the spar236through any suitable method such as, but not limited to, threading, bonding, fastening or adhesion with the trunnion234or the spar236. It is further contemplated that additional components can be included to couple the retention block274to the trunnion234and/or spar236. As a non-limiting example, the trunnion234can include a threaded section corresponding to a threaded section of the retention block274. A groove can be carved into the threaded section of the retention block274and/or the trunnion234such that the groove runs transverse the threads. The retention block274can be threaded to the trunnion234, and an insert (e.g., a thread stake) can be placed into the groove to effectively lock the retention block274and the trunnion234together.

The retention block274can be integrally formed with, coupled to, or otherwise provided against the wedge272. As a non-limiting example, the wedge272and the retention block274can be integrally formed such that they form a unitary body.

The trunnion234can take any suitable shape. As a non-limiting example, the trunnion234can be sized such that the retention block274is at least partially disposed within the flared socket264against a respective portion of the first end260. As a non-limiting example, the bottom268can be sized such that retention block274can fit through an opening along the bottom268and confront the interior surface262of the trunnion234.

The retention block274can include any suitable material. As a non-limiting example, the retention block274can include a composite material or a metallic material.

The retention block274can be used to secure the wedge272within the intervening gap258. The retention block274can further be used to limit an axial movement of the spar236within the flared socket264, with respect to the centerline axis250.

FIG.6is a schematic cross-sectional view of an exemplary airfoil assembly330suitable for use as the airfoil assembly ofFIG.3. The airfoil assembly330is similar to the airfoil assembly130,230; therefore, like parts will be identified with like numerals increased to the300series with it being understood that description of the airfoil assembly130,230applies to the airfoil assembly330unless noted otherwise.

The airfoil assembly330includes a trunnion334and a spar336. The trunnion334includes a wall363defining an interior surface362at least a partially defining a flared socket364that extends between an open top370and a bottom368. The spar336extends along a centerline axis350and terminates within the flared socket364at a first end360. The spar336includes a furcated tail352with at least a first branch354and a second branch356. The furcated tail352can define a set of intervening gaps358, with one gap of the set of intervening gaps358sized to receive a wedge372. The wedge extends axially into the spar336and terminates at an apex359.

The airfoil assembly330is similar to the airfoil assembly130,230in that it uses the wedge272to retain the spar236within the trunnion234. The furcated tail352, however, further includes a third branch376and a fourth branch377such that the set of intervening gaps358includes multiple intervening gaps. As a non-limiting example, the set of intervening gaps358can include a first intervening gap, a second intervening gap, and a third intervening gap, with the largest of the three intervening gaps being provided between the other two intervening gaps. It will be appreciated that the set of intervening gaps358can be symmetric or asymmetric about the centerline axis350. There can be any number of two or more intervening gaps in the set of intervening gaps358.

A set of inserts378can be provided within a remainder of the set of intervening gaps358that do not include the wedge372. The set of inserts378can be used to increase the overall radial thickness of the furcated tail352. The set of inserts378can include any suitable material. As a non-limiting example, the set of inserts378can include a composite material. As a non-limiting example, both of the spar336and the set of inserts378can include a composite material. The set of inserts378can be bonded to the spar336such that the set of inserts378and the spar336form a unitary body.

Each intervening gap of the set of intervening gaps358can be defined by a respective cross section. It will be appreciated that the cross section between the intervening gaps of the set of intervening gaps358can be the same or different. As a non-limiting example, the intervening gap of the set of intervening gaps358that houses the wedge372can be larger than the intervening gaps of the set of intervening gaps358that house the set of insert378. The set of intervening gaps358can be symmetric or asymmetric about the centerline axis350.

The set of inserts378can be retained within the respective gaps of the set of intervening gaps358through any suitable method such as, but not limited to, bonding. As a non-limiting example, the set of inserts378can be pressed into the respective gaps of the set of intervening gaps358and held in contact with the set of intervening gaps358through use of a retention block (e.g., the retention block274ofFIG.5).

FIG.7is a schematic, top-down view of an exemplary airfoil assembly430suitable for use as the airfoil assembly130ofFIG.3The airfoil assembly430is similar to the airfoil assembly130,230,330; therefore, like parts will be identified with like numerals increased to the400series with it being understood that description of the airfoil assembly130,230,330applies to the airfoil assembly430unless noted otherwise.

The airfoil assembly430includes a trunnion434and a spar436. The trunnion434includes a wall463defining an interior surface462and an open top470. The spar436extends along a centerline axis450. The illustrated view is of a top-down view of a horizontal plane that is perpendicular to the centerline axis450and cuts the trunnion434near the open top470.

The airfoil assembly430is similar to the airfoil assembly130,230,330in that it uses a wedge472(FIG.8) to retain the spar436within the trunnion434. The trunnion434and the spar436, however, include varying cross sections when viewed along a horizontal plane that is perpendicular to the centerline axis450. As a non-liming example, the open top470includes a circular cross section that circumscribes a rectangular cross section of the spar436. A set of spacers480can be provided to fill the gap between the interior surface462and the spar436. There can be any number of one or more spacers in the set of spacers480that extend continuously or non-continuously about the centerline axis450.

FIG.8is a schematic, bottom-up view of the exemplary airfoil assembly430ofFIG.7.FIG.8is a bottom-up view along a horizontal plane that is perpendicular to the centerline axis450and runs along a first end460of the spar436. The spar436terminates at the first end460. The bottom (e.g., the bottom168ofFIG.3) can have a varying cross section with respect to spar436at the first end460. The set of spacers480can be used to fill the gap between the interior surface462and the spar436.

The set of spacers480can extend along any suitable portion of the centerline axis450. As a non-limiting example, the set of spacers480can terminate at the first end460of the spar436and at the open top470of the trunnion434. As a non-limiting example, at last a portion of the set of spacers480can extend axially beyond, with respect to the centerline axis450, the first end460and/or the open top470.

Benefits associated with the present disclosure include an airfoil assembly with a decreased complexity when compared to a conventional airfoil assembly. For example, the conventional airfoil assembly including a spar and trunnion requires additional structure to ensure that the airfoil of the conventional airfoil assembly is coupled to the trunnion. For example, the conventional airfoil assembly can require a physical connection or mechanical connection between the spar and the trunnion. This physical or mechanical connection between the spar and the trunnion results in a relatively complex airfoil assembly when compared to the airfoil assembly as described herein. The conventional airfoil assembly can further require that the spar is physically coupled to or formed with the trunnion, which in turn can make assembling and disassembling (e.g., during maintenance) difficult. The airfoil assembly, as described herein, however, includes the spar with a furcated tail and the intervening gap with the wedge received within the intervening gap. The wedge is used to retain the spar within the trunnion without having to physically couple (e.g., through welding, adhesion, or fastening) the spar to the trunnion. This configuration of the airfoil assembly greatly reduces the complexity of the airfoil assembly with respect to the conventional airfoil assembly.

To the extent not already described, the different features and structures of the various embodiments can be used in combination, or in substitution with each other as desired. That one feature is not illustrated in all of the embodiments is not meant to be construed that it cannot be so illustrated, but is done for brevity of description. Thus, the various features of the different embodiments can be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure.

An airfoil assembly for a turbine engine, the airfoil assembly comprising an airfoil comprising a wall bounding an interior and defining an exterior surface, the wall extending between a leading edge and a trailing edge to define a chordwise direction, and between a root and a tip to define a spanwise direction, a trunnion having a wall with an interior surface defining a flared socket with an open top, a spar extending from the flared socket, through the open top of the flared socket, and into the interior of the airfoil, the spar having a furcated tail with a set of branches and an intervening gap defined between each adjacent branch of the set of branches, and a wedge received within at least one intervening gap for retaining the spar against the interior surface within the flared socket.

A turbine engine comprising an airfoil assembly having an airfoil comprising a wall bounding an interior and defining an exterior surface, the wall extending between a leading edge and a trailing edge to define a chordwise direction, and between a root and a tip to define a spanwise direction, a trunnion having a wall with an interior surface defining a flared socket with an open top, a spar extending from the flared socket, through the open top of the flared socket, and into the interior of the airfoil, the spar having a furcated tail with a set of branches and an intervening gap defined between each adjacent branch of the set of branches, and a wedge received within at least one intervening gap for retaining the spar against the interior surface within the flared socket.

A turbine engine comprising an airfoil assembly having a composite airfoil, a metal trunnion having a wall with an interior surface defining a flared socket with an open top, a composite spar extending from the flared socket, through the open top, and into an interior of the composite airfoil, the composite spar having a furcated tail defining first and second branches with an intervening gap therebetween, and a wedge received within the intervening gap for retaining the composite spar against the interior surface within the flared socket.

An airfoil assembly, comprising a composite airfoil, a metal trunnion having a wall with an interior surface defining a flared socket with an open top, a composite spar extending from the flared socket, through the open top, and into an interior of the composite airfoil, the composite spar having a furcated tail defining first and second branches with an intervening gap therebetween, and a wedge received within the intervening gap for retaining the composite spar against the interior surface within the flared socket.

The airfoil assembly of any preceding clause, wherein the at least one intervening gap includes a first intervening gap and one of the one or more additional intervening gaps, with the wedge being received within the first intervening gap and an insert being received within each of the one of the one or more additional intervening gaps, the at least one insert being used to increase the thickness of the furcated tail.

The airfoil assembly of any preceding clause, wherein the spar includes a first composite material and the insert includes a second composite material.

The airfoil assembly of any preceding clause, wherein the first composite material is different from the second composite material.

The airfoil assembly of any preceding clause, wherein the first composite material is the same as the second composite material.

The airfoil assembly of any preceding clause, wherein the each of the one or more additional intervening gaps is smaller than the first intervening gap.

The airfoil assembly of any preceding clause, wherein the one or more additional intervening gaps includes second and third intervening gaps with the first intervening gap positioned therebetween.

The airfoil assembly of any preceding clause, wherein the spar extends along a centerline axis in the spanwise direction, with the furcated tail being symmetric about the centerline axis.

The airfoil assembly of any preceding clause, wherein the trunnion includes a metallic material and the spar includes a composite material.

The airfoil assembly of any preceding clause, wherein the spar extends along a centerline axis in the spanwise direction, the spar including a rectangular cross-sectional area when viewed along a horizontal plane perpendicular to the centerline axis.

The airfoil assembly of any preceding clause, wherein the flared socket includes a circular cross-sectional area when viewed along the horizontal plane.

The airfoil assembly of any preceding clause, further comprising at least one spacer provided between an inner wall of the flared socket and the spar such that the spar, the trunnion and the spacer form a continuous cross-sectional area when viewed along the horizontal plane.

The airfoil assembly of any preceding clause, wherein the spar extends along a centerline axis in the spanwise direction, and the open top includes a rectangular cross-sectional area when viewed along a plane perpendicular to the centerline axis.

The airfoil assembly of any preceding clause, further comprising a retention block provided inwardly from the furcated tail in the spanwise direction, the retention block pressing against at least the wedge and the furcated tail to retain the wedge within the intervening gap.

The airfoil assembly of any preceding clause, wherein the retention block is threaded into the trunnion.

The airfoil assembly of any preceding clause, wherein the retention block includes a composite or a metallic material.

The airfoil assembly of any preceding clause, wherein the airfoil is a composite fan blade provided within the fan section of the turbine engine.

The airfoil assembly of any preceding clause, wherein at least one of the spar, the trunnion or the wedge includes a composite material that is at least one of a polymer matrix composite, a ceramic matrix composite, a metal matrix composite, a carbon fiber, a polymeric resin, a thermoplastic resin, a bismaleimide material, a polyimide material, an epoxy resin, a glass fiber, or a silicon matrix material.

The airfoil assembly of any preceding clause, further comprising a set of inserts provided within a portion of the furcated tail, the set of inserts being used to increase a thickness of the furcated tail.

The airfoil assembly of any preceding clause wherein the airfoil includes a composite material.

The airfoil assembly of any preceding clause, further comprising a set of inserts provided within a portion of the furcated tail, the set of inserts being used to increase a thickness of the furcated tail.