Patent ID: 12188551

DETAILED DESCRIPTION

FIG.1schematically illustrates a propulsion system20for an aircraft. The aircraft may be an airplane, a helicopter, a drone (e.g., an unmanned aerial vehicle (UAV)), a spacecraft or any other manned or unmanned aerial vehicle or system. This aircraft may be configured as a vertical take-off and landing (VTOL) aircraft or a short take-off and vertical landing (STOVL) aircraft. The aircraft propulsion system20ofFIG.1, for example, is configured to generate power for first direction propulsion (e.g., propulsive thrust) during a first mode of operation and to generate power for second direction propulsion (e.g., propulsive lift) during a second mode of operation, where the first direction is different than (e.g., angularly offset from) the second direction. The first mode may be a horizontal flight mode (e.g., a forward flight mode) where the first direction propulsion is substantially horizontal propulsive thrust; e.g., within five degrees (5°), ten degrees (10°), etc. of a horizontal axis. The second mode may be a vertical flight and/or hover mode where the second direction propulsion is substantially vertical propulsive lift; e.g., within five degrees (5°), ten degrees (10°), etc. of a vertical axis. The aircraft propulsion system20, of course, may also be configured to generate both the first direction propulsion (e.g., horizontal propulsion) and the second direction propulsion (e.g., vertical propulsion) during a third mode (e.g., a transition mode) of operation.

The aircraft propulsion system20ofFIG.1includes one or more bladed propulsor rotors such as, for example, at least one bladed first propulsor rotor22and at least one bladed second propulsor rotor24. The aircraft propulsion system20ofFIG.1also includes a gas turbine engine with a core26configured to rotatably drive the one or more propulsor rotors—the first propulsor rotor22and/or the second propulsor rotor24.

The first propulsor rotor22may be configured as a ducted rotor such as a fan rotor. Of course, in other embodiments, the first propulsor rotor22may alternatively be configured as an open rotor (e.g., an un-ducted rotor) such as a propeller rotor, a pusher fan rotor or the like. The first propulsor rotor22ofFIG.1is rotatable about a first rotor axis28. This first rotor axis28is an axial centerline of the first propulsor rotor22and may be horizontal when the aircraft is on ground and/or during level aircraft flight. The first propulsor rotor22includes at least a first rotor disk29(or a hub) and a plurality of first rotor blades30(one visible inFIG.1); e.g., fan blades. The first rotor blades30are distributed circumferentially around the first rotor disk29in an annular array. Each of the first rotor blades30is connected to and projects radially (relative to the first rotor axis28) out from the first rotor disk29.

The second propulsor rotor24may be configured as an open rotor such as a propeller rotor or a helicopter (e.g., main) rotor. Of course, in other embodiments, the second propulsor rotor24may alternatively be configured as a ducted rotor such as a fan rotor; e.g., see dashed line duct. The second propulsor rotor24ofFIG.1is rotatable about a second rotor axis32. This second rotor axis32is an axial centerline of the second propulsor rotor24and may be vertical when the aircraft is on the ground and/or during level aircraft flight. The second rotor axis32is angularly offset from the first rotor axis28by an included angle34; e.g., an acute angle or a right angle. This included angle34may be between sixty degrees (60°) and ninety degrees (90°); however, the present disclosure is not limited to such an exemplary relationship. The second propulsor rotor24includes at least a second rotor disk36(or a hub) and a plurality of second rotor blades38; e.g., open rotor blades. The second rotor blades38are distributed circumferentially around the second rotor disk36in an annular array. Each of the second rotor blades38is connected to and projects radially (relative to the second rotor axis32) out from the second rotor disk36.

The engine core26extends axially along a core axis40from a forward, upstream airflow inlet42into the engine core26to an aft, downstream combustion products exhaust44from the engine core26. The core axis40may be an axial centerline of the engine core26and may be horizontal when the aircraft is on the ground and/or during level aircraft flight. This core axis40may be parallel (e.g., coaxial) with the first rotor axis28and, thus, angularly offset from the second rotor axis32. The engine core26ofFIG.1includes a compressor section46, a combustor section47and a turbine section48. The turbine section48ofFIG.1includes a high pressure turbine (HPT) section48A and a low pressure turbine (LPT) section48B (also sometimes referred to as a power turbine section).

The engine sections46-48B may be arranged sequentially along the core axis40within an engine housing50. This engine housing50includes an inner case52(e.g., a core case) and an outer case54(e.g., a fan case). The inner case52may house one or more of the engine sections46-48B; e.g., the engine core26. The outer case54may house the first propulsor rotor22. The outer case54ofFIG.1also axially overlaps and extends circumferentially about (e.g., completely around) the inner case52thereby at least partially forming a (e.g., annular) bypass flowpath56radially between the inner case52and the outer case54.

Each of the engine sections46,48A,48B includes a bladed rotor58-60within that respective engine section46,48A,48B. Each of these engine rotors58-60includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks (or hubs). The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed and/or otherwise attached to the respective rotor disk(s) (or hub(s)).

The compressor rotor58is connected to the HPT rotor59through a high speed shaft62. At least (or only) these engine components58,59and62collectively form a high speed rotating assembly64; e.g., a high speed spool. This high speed rotating assembly64is rotatable about the core axis40. The LPT rotor60is connected to a low speed shaft66. At least (or only) these engine components60and66collectively form a low speed rotating assembly68; e.g., a low speed spool. This low speed rotating assembly68is rotatable about the core axis40. The low speed rotating assembly68and, more particularly, its low speed shaft66may project axially through a bore of the high speed rotating assembly64and its high speed shaft62.

The aircraft propulsion system20ofFIG.1and its turbine engine include a drivetrain70that couples the low speed rotating assembly68to the first propulsor rotor22and that couples the low speed rotating assembly68to the second propulsor rotor24. The drivetrain70ofFIG.1includes a geartrain72, a transmission76and a gearing78; e.g., bevel gearing. The drivetrain70ofFIG.1also includes one or more shafts80and82and/or other intermediate torque transmission devices for coupling the low speed rotating assembly68and its low speed shaft66to the second propulsor rotor24. The drivetrain70may also include one or more intermediate torque transmission devices for coupling the geartrain72to the first propulsor rotor22; e.g., a first propulsor shaft84.

An input into the geartrain72is coupled to the low speed rotating assembly68and its low speed shaft66, where the low speed rotating assembly68forms a power input for the geartrain72. An output from the geartrain72is coupled to the first propulsor rotor22through the first propulsor shaft84, where the first propulsor rotor22forms a power output (e.g., load) for the geartrain72.

An input into the transmission76may be coupled to the low speed rotating assembly68independent of the geartrain72. The low speed rotating assembly68, for example, may be coupled to the input of the geartrain72and the input of the transmission76in parallel. The input of the transmission76ofFIG.1, in particular, is (e.g., directly or indirectly) connected to the LPT rotor60through the low speed shaft66; e.g., without passing through the geartrain72. An output from the transmission76is connected to an input into the gearing78through the transmission output shaft80.

The transmission76may be configured to selectively couple (e.g., transfer mechanical power between) the low speed rotating assembly68and the transmission output shaft80. During the first mode of operation, for example, the transmission76may be configured to decouple the low speed rotating assembly68from the transmission output shaft80, thereby decoupling the low speed rotating assembly68from the second propulsor rotor24. During the second mode of operation (and the third mode of operation), the transmission76may be configured to couple the low speed rotating assembly68with the transmission output shaft80, thereby coupling the low speed rotating assembly68with the second propulsor rotor24. The transmission76may be configured as a clutched transmission or a clutchless transmission.

An output from the gearing78is connected to the second propulsor rotor24through the second propulsor shaft82. This gearing78provides a coupling between the transmission output shaft80rotating about the axis28,40and the second propulsor shaft82rotating about the second rotor axis32. The gearing78may also provide a speed change mechanism between the transmission output shaft80and the second propulsor shaft82. The gearing78, however, may alternatively provide a1:1rotational coupling between the transmission output shaft80and the second propulsor shaft82such that these shafts80and82rotate at a common (e.g., the same) rotational velocity. Furthermore, in some embodiments, the gearing78and the transmission output shaft80may be omitted where the functionality of the gearing78is integrated into the transmission76. In still other embodiments, the transmission76may be omitted where decoupling of the second propulsor rotor24is not required and/or where an optional additional speed change between the low speed rotating assembly68and the second propulsor rotor24is not required.

During operation of the aircraft propulsion system20, air enters the engine core26through the core inlet42. This air is directed into a (e.g., annular) core flowpath86, which core flowpath86extends sequentially through the compressor section46, the combustor section47, the HPT section48A and the LPT section48B from the core inlet42to the core exhaust44. The air within this core flowpath86may be referred to as core air.

The core air is compressed by the compressor rotor58and directed into a (e.g., annular) combustion chamber88of a (e.g., annular) combustor90in the combustor section47. Fuel is injected into the combustion chamber88through one or more fuel injectors92(one visible inFIG.1) and mixed with the compressed core air to provide a fuel-air mixture. This fuel-air mixture is ignited and combustion products thereof flow through and sequentially cause the HPT rotor59and the LPT rotor60to rotate. The rotation of the HPT rotor59drives rotation of the high speed rotating assembly64and its compressor rotor58. The rotation of the LPT rotor60drives rotation of the low speed rotating assembly68. The rotation of the low speed rotating assembly68drives rotation of the first propulsor rotor22through the geartrain72during one or more modes of operation; e.g., the first, the second and the third modes of operation. The rotation of the low speed rotating assembly68drives rotation of the second propulsor rotor24(e.g., independent of the geartrain72) during one or more modes of operation; e.g., the second and the third modes of operation. During the first mode of operation, the transmission76may decouple the low speed rotating assembly68from the second propulsor rotor24such that the low speed rotating assembly68does not drive rotation of the second propulsor rotor24. The second propulsor rotor24may thereby be stationary (or windmill) during the first mode of operation.

During the first and the third modes of operation, the rotation of the first propulsor rotor22propels bypass air (separate from the core air) through the aircraft propulsion system20and its bypass flowpath56to provide the first direction propulsion; e.g., the forward, horizontal thrust. During the second and the third modes of operation, the rotation of the second propulsor rotor24propels additional air (separate from the core air and the bypass air) to provide the second direction propulsion; e.g., vertical lift. The aircraft may thereby takeoff, land and/or otherwise hover during the second and the third modes of operation, and the aircraft may fly forward or otherwise move during the first and the third modes of operation. The bypass air may also flow through the bypass flowpath56during the second and the third modes of operation; however, a quantity of the bypass air flowing through the bypass flowpath56during the second mode of operation may be de minimis as described below in further detail.

Referring toFIG.2, the geartrain72may include multiple (e.g., epicyclic) interconnected gear systems94and96. Referring toFIGS.2and3, the first gear system94has a plurality of first gear system components including a first sun gear98, a first ring gear100, a plurality of first intermediate gears102and a first carrier104. The first sun gear98is rotatable about a rotational axis106of the geartrain72, which rotational axis106may be parallel (e.g., coaxial) with the axis28,40. The first ring gear100circumscribes the first sun gear98and the first intermediate gears102. The first ring gear100is rotatable about the axis28,40,106. The first intermediate gears102are arranged circumferentially about the axis28,40,106and the first sun gear98in an array. Each of the first intermediate gears102is disposed radially between and meshed with the first sun gear98and the first ring gear100. Each of the first intermediate gears102is rotatably mounted to the first carrier104. The first carrier104is rotatable about the axis28,40,106.

Referring toFIGS.2and4, the second gear system96has a plurality of second gear system components including a second sun gear108, a second ring gear110, a plurality of second intermediate gears112and a second carrier114. The second sun gear108is rotatable about the axis28,40,106. The second ring gear110circumscribes the second sun gear108and the second intermediate gears112. The second ring gear110is rotatable about the axis28,40,106. The second intermediate gears112are arranged circumferentially about the axis28,40,106and the second sun gear108in an array. Each of the second intermediate gears112is disposed radially between and meshed with the second sun gear108and the second ring gear110. Each of the second intermediate gears112is rotatably mounted to the second carrier114. The second carrier114is rotatable about the axis28,40,106. This second carrier114is coupled to (e.g., via an inter-gear system shaft and/or another drive element) and rotatable with the first ring gear100, where the second carrier114and the first ring gear100are configured to rotate at a common rotational velocity.

Referring toFIG.2, the first propulsor rotor22is coupled to the geartrain72and its second gear system96through the second ring gear110. The first propulsor shaft84(and/or another drive element), for example, may couple the first propulsor rotor22to the second ring gear110. The first propulsor shaft84ofFIG.2extends between and is connected to the first propulsor rotor22and the second ring gear110. The low speed rotating assembly68and its low speed shaft66are coupled to the geartrain72and its first gear system94through the first sun gear98. The low speed rotating assembly68and its low speed shaft66are also coupled to the geartrain72and its second gear system96through the second sun gear108. The first sun gear98and the second sun gear108ofFIG.2, for example, are each (e.g., independently) connected to the low speed rotating assembly68and its low speed shaft66. With such an arrangement, the low speed rotating assembly68and its LPT rotor60are configured to (e.g., independently) drive rotation of the first sun gear98and the second sun gear108, where the first sun gear98, the second sun gear108and the LPT rotor60are rotate at a common rotational velocity.

The aircraft propulsion system20and its drivetrain70may include one or more brakes116A and116B (generally referred to as “116”) and/or one or more lock devices118A and118B (generally referred to as “118”). The first brake116A and/or the first lock device118A may be located at a first location120A, or another suitable location. The second brake116B and/or the second lock device118B may be located at a second location120B, or another suitable location.

The first brake116A ofFIG.2is configured to brake (e.g., slow and/or stop) rotation of the first carrier104about the axis28,40,106. The second lock device118B is configured to lock (e.g., fix, prevent) rotation of the first ring gear100and the second carrier114about the axis28,40,106, for example, following the braking of the second carrier114to a zero rotational speed about the axis28,40,106using the second brake116B. When the second carrier114is rotationally fixed (e.g., during the second mode of operation ofFIG.5), a rotational speed of the first propulsor rotor22may decrease (compared to when the second carrier114is free to rotate).

Reducing the rotational speed of the first propulsor rotor22during, for example, the second mode of operation reduces or substantially eliminates (e.g., de minimis) the first direction propulsive thrust generated by the first propulsor rotor22. Reducing first propulsor rotor thrust may, in turn, increase power available for driving rotation of the second propulsor rotor24and/or facilitate substantial second direction aircraft movement; e.g., without first direction aircraft movement. However, maintaining some rotation of the first propulsor rotor22may maintain lubrication of one or more bearings (e.g., bearings122inFIG.2) supporting the first propulsor rotor22and/or prevent bearing related damage. For example, when a component supported by a bearing is not rotating, shock loads may damage one of more internal components of the bearing. Examples of such bearing damage may include, but are not limited to, brinelling and false brinelling. Maintaining some rotation of the first propulsor rotor22ofFIG.1may also or alternatively prevent an exhaust backflow through the bypass flowpath56into the core inlet42. Maintaining some rotation of the first propulsor rotor22may still also or alternatively prevent debris (e.g., sand, dirt, dust, etc.) from entering the core inlet42during the second mode of operation where the aircraft is more likely to be near the ground; e.g., for landing or takeoff.

The second brake116B ofFIG.2is configured to brake (e.g., slow and/or stop) rotation of the first ring gear100about the axis28,40,106and, thus, rotation of the second carrier114about the axis28,40,106. The first lock device118A is configured to lock (e.g., fix, prevent) rotation of the first carrier104about the axis28,40,106. With this arrangement, the geartrain72and its first gear system94and its second gear system96are configured to transfer additional power from the low speed rotating assembly68and its LPT rotor60to the first propulsor rotor22and any drivetrain element(s) therebetween (when included). This power transfer may be substantially all (e.g., minus losses in the drivetrain70) of the power output from the low speed rotating assembly68and its LPT rotor60when the second propulsor rotor24is rotationally decoupled from the low speed rotating assembly68; e.g., using the transmission76ofFIG.1. The geartrain72may thereby provide a multi-speed transmission between the low speed rotating assembly68and the first propulsor rotor22, where a speed ratio between the low speed rotating assembly68and the first propulsor rotor22during the second mode is less than a speed ratio between the low speed rotating assembly68and the first propulsor rotor22during the first mode.

To enter the third mode of operation from the first mode of operation, the first lock device118A may be disengaged and/or the first brake116A may be released (if currently applied). The second propulsor rotor24may thereby begin to rotate along with the already rotating first propulsor rotor22. Similarly, to enter the third mode of operation from the second mode of operation, the second lock device118B may be disengaged and/or the second brake116B may be released (if currently applied). The first propulsor rotor22may thereby begin to rotate faster along with the already rotating second propulsor rotor24. When both of the first propulsor rotor22and the second propulsor rotor24are rotating/free to rotate, the drivetrain70may transfer (e.g., all, minus losses in the drivetrain70) the power output from the low speed rotating assembly68and its LPT rotor60to (a) the first propulsor rotor22and the drivetrain element(s) therebetween and (b) the second propulsor rotor24and the drivetrain element(s) therebetween (e.g., independent of the geartrain72and its first gear system94and its second gear system96).

Referring toFIG.6, the first brake116A and/or the second brake116B may each be configured as or otherwise include a disk brake124. The disk brake124ofFIG.6includes a brake rotor126and one or more brake pads128. The brake rotor126is configured rotatable with the respective geartrain member104,100. The brake rotor126, for example, may be connected to and rotatable with the respective geartrain member104,100, or another rotating element (directly or indirectly) rotatable with the respective geartrain member104,100. The brake pads128are anchored to a stationary structure130, which may be part of the engine housing50and/or an airframe of the aircraft (seeFIG.1). The brake pads128may be actuated by one or more brake actuators132(e.g., hydraulic brake actuators) to move the brake pads128from an open position to a closed position. In the open position, the brake pads128are spaced from and do not engage (e.g., contact) the brake rotor126(see position ofFIG.6). In the closed position, the brake pads128engage (e.g., contact) and clamp onto (e.g., squeeze) the brake rotor126. Frictional rubbing between the brake pads128and the brake rotor126is operable to brake rotation of the brake rotor126and, thus, the respective geartrain member104,100(or another rotating element) connected thereto. The first and the second brakes116of the present disclosure, however, are not limited to such an exemplary disk brake configuration. For example, it is contemplated the first and/or the second brake116B may alternatively be configured as another type of brake such as a drum brake or a set of clutch plates.

Referring toFIG.7, the first lock device118A and/or the second lock device118B may each be configured as a splined lock device; e.g., a splined coupling. The lock device118ofFIG.7, for example, includes an inner lock element134(e.g., a splined shaft), an outer lock element136(e.g., a splined sleeve) and an actuator138. The inner lock element134is rotatable about the axis28,40,106. The outer lock element136is rotationally fixed about the axis28,40,106. However, the actuator138is configured to move (e.g., axially translate) the outer lock element136along the axis28,40,106and the inner lock element134between an unlocked position (see dashed line inFIG.7) and a locked position (see solid line inFIG.7; see alsoFIG.8). At the unlocked position, inner splines140of the outer lock element136are disengaged (e.g., spaced) from outer splines142of the inner lock element134. At the locked position, the inner splines140of the outer lock element136are engaged (e.g., meshed) with the outer splines142of the inner lock element134(see alsoFIG.8). With this arrangement, when the lock device118is unlocked and its outer lock element136is in the unlocked position, the inner lock element134may rotate (e.g., freely, unencumbered by the outer lock element136) about the axis28,40,106. However, when the lock device118is locked and its outer lock element136is in the locked position ofFIG.8, the outer lock element136is meshed with the inner lock element134and prevents rotation of the inner lock element134about the axis28,40,106.

Referring toFIGS.2and7, the inner lock element134of the first lock device118A may be configured as part of or may be attached (directly or indirectly) to the first carrier104, or any other element rotatable therewith. The inner lock element134of the second lock device118B may be configured as part of or may be attached (directly or indirectly) to the first ring gear100, or any other element rotatable therewith. While the inner lock element134ofFIGS.7and8is described as the rotating element and the outer lock element136is described as the rotationally fixed element, the operation of these elements may be switched in other embodiments. In particular, the inner lock element134may alternatively be configured as the rotationally fixed element and axially translatable by the actuator138, and the outer lock element136may be configured as the rotating element. Furthermore, various other types of rotational lock devices are known in the art, and the present disclosure is not limited to any particular ones thereof.

FIG.9partially illustrates an assembly144for the aircraft propulsion system20and its turbine engine. This engine assembly144includes the geartrain72, a rotating structure146, a support structure148and a bearing150. The engine assembly144ofFIG.9also includes a fluid circuit152(e.g., a lubricant circuit) configured to deliver fluid (e.g., lubricant) to one or more components of the geartrain72and/or the bearing150.

The rotating structure146may form, or may otherwise be connected to and rotatable with, a component of the geartrain72/one of its gear systems94,96. The rotating structure146ofFIG.9, for example, forms the first carrier104. The rotating structure146ofFIG.9, in particular, includes the first carrier104, a rotating structure shaft154and an internal rotating structure passage156.

The rotating structure shaft154is connected to (e.g., formed integral with or otherwise fixedly attached to) and rotatable with the first carrier104. This rotating structure shaft154ofFIG.9projects axially out (e.g., in an aft direction away from the geartrain72and towards the LPT rotor60ofFIG.1) from the first carrier104along the axis28,40,106to an axial distal end158of the rotating structure146and its rotating structure shaft154. The rotating structure shaft154extends radially from a radial inner side160of the rotating structure146and its rotating structure shaft154to a radial outer side162of the rotating structure shaft154. The rotating structure shaft154includes an inner bearing mount164and a fluid device land166; e.g., a cylindrical outer surface. The inner bearing mount164is disposed axially between the fluid device land166and the rotating structure distal end158; e.g., at or about the rotating structure distal end158. The fluid device land166is disposed at the shaft outer side162, axially between the inner bearing mount164and the first carrier104.

The rotating structure passage156includes an inlet port168(or multiple inlet ports arranged circumferentially about the axis28,40,106) at the shaft outer side162. The inlet port168ofFIG.9, in particular, forms an inlet opening to the rotating structure passage156in the fluid device land166. The rotating structure passage156ofFIG.9is disposed within the rotating structure146and its rotating structure shaft154. This rotating structure passage156extends (e.g., axially) within the rotating structure146and its rotating structure shaft154away from its inlet port168(e.g., in opposing axial directions) and towards the geartrain72and/or the bearing150.

The support structure148is disposed radially outboard of the rotating structure shaft154, where a radial inner side170of the support structure148radially faces the shaft outer side160. The support structure148extends axially along and circumferentially about the axis28,40,106and the rotating structure shaft154. The support structure148thereby axially overlaps and circumscribes the rotating structure shaft154. The support structure148ofFIG.9includes an outer bearing mount172and a fluid device174.

The outer bearing mount172is disposed radially outboard of and axially aligned with the inner bearing mount164. The bearing150is disposed radially between and engaged with the inner bearing mount164and the outer bearing mount172. This bearing150rotatably couples the rotating structure146and its rotating structure shaft154to the support structure148. The bearing150ofFIG.9, for example, is configured as a rolling element bearing. This bearing150includes an inner race176, an outer race178and a plurality of bearing elements180. The inner race176circumscribes and is mounted to the inner bearing mount164; however, it is contemplated the inner race176may alternatively be configured integral with the rotating structure146and its rotating structure shaft154. The outer race178is nested in a bore of and is mounted to the outer bearing mount172; however, it is contemplated the outer race178may alternatively be configured integral with the support structure148. The bearing elements180are arranged circumferentially about the axis28,40,106in an array, where the array of the bearing elements180circumscribes the inner race176. Each bearing element180is disposed radially between and is engaged with (e.g., contacts) the inner race176and the outer race178.

The fluid device174is connected to (e.g., formed integral with or otherwise fixedly attached to) the outer bearing mount172. The fluid device174may be configured as a fluid coupling and/or a fluid damper. The fluid device174ofFIG.9, for example, includes a support structure passage182and an annular channel184. The support structure passage182extends radially (in a radial inward direction towards the axis28,40,106) into the support structure148and its fluid device174to the channel184. The channel184extends radially (in a radial outward direction away from the axis28,40,106) into the support structure148and its fluid device174to the support structure passage182. This channel184extends axially within the support structure148and its fluid device174between opposing axial sidewalls, and may have a larger axial width than the support structure passage182. The channel184extends within the support structure148and its fluid device174circumferentially about (e.g., completely around) the axis28,40,106.

The fluid device174is axially aligned with the rotating structure shaft154and its fluid device landing166. The fluid device174is also radially outboard of and radially adjacent (but, slightly radially spaced from) the rotating structure shaft154and its fluid device landing166. With this arrangement, a fluid plenum186(e.g., an annular lubricant plenum) is formed by and radially between the rotating structure shaft154and the fluid device174. This fluid plenum186includes the channel184as well as a radial clearance gap188between an inner surface of the fluid device174at its inner side170and the fluid device landing166. The fluid plenum186and its clearance gap188are axially bounded by (e.g., extend axially between) a plurality of seal elements190and192(e.g., annular seal elements, seal rings, etc.), where each seal element190,192is radially between and engaged with the fluid device174and the rotating structure shaft154. With this arrangement, the fluid plenum186fluidly couples the support structure passage182to the rotating structure passage156. The fluid device174ofFIG.9is further axially adjacent the bearing150, and maybe arranged radially inboard of the outer bearing mount172and the attached outer race178.

The fluid circuit152ofFIG.9includes a fluid conduit194(e.g., a lubricant conduit), the rotating structure passage156, the support structure passage182and the fluid plenum186. The fluid conduit194is fluidly coupled to the support structure passage182. The fluid conduit194is configured to receive a flow of fluid such as lubricant from a fluid source196(e.g., a lubricant reservoir and/or a lubricant pump), and direct that fluid flow through the support structure passage182and the fluid plenum186and into the rotating structure passage156. The rotating structure passage156may then facilitate delivery of the fluid flow to one or more components of the geartrain72(e.g., the first carrier104and the first intermediate gears102ofFIG.2) and/or the bearing150. Here, the fluid device174provides the fluid coupling between the stationary fluid conduit194and the rotating structure passage156. The fluid plenum186and its channel184may also be sized to provide fluidic damping for the rotating structure146and its rotating structure shaft154. Moreover, by integrating the fluid device174into the same (e.g., monolithic, unitary) structure as the outer bearing mount172, a radial height of the clearance gap188may be sized relatively small since the bearing150maintains a relative radial position between the rotating structure shaft154and the fluid device174. Reducing the clearance gap188height and/or maintaining the relative position between the rotating structure shaft154and the fluid device174may also reduce likelihood for fluid leakage axially across the seal elements190and192.

In some embodiments, the support structure148may be connected to a stationary structure198of the aircraft propulsion system20through a compliant coupling200; e.g., an axial or tangential squirrel cage coupling, a spring coupling, etc. This compliant coupling200is configured to facilitate (e.g., slight) radial movement between the support structure148and the stationary structure198, which may reduce bending moment loads, vibration loads, etc. on the rotating structure146. However, a radial stop202(e.g., a bumper) may be provided to limit this radial movement. The radial stop202ofFIG.9, for example, is axially aligned with and circumscribes the outer bearing mount172and the bearing150. The radial stop202is further (e.g., stiffly) connected to the stationary structure198. Thus, a relative position between the radial stop202and the stationary structure198may remain unchanged even as the support structure148moves radially relative to the stationary structure198. A radial gap between the radial stop202and the outer bearing mount172may be sized to tailor the radial movement of the support structure148and its outer bearing mount172.

In some embodiments, referring toFIG.10, the fluid conduit194may be configured with one or more bends204. These bends204may be provided to facilitate the radial compliance/movement between the support structure148and the stationary structure198. Referring toFIG.11, the fluid conduit194may also or alternatively be provided with a slip joint206to facilitate the radial compliance/movement between the support structure148and the stationary structure198.

In some embodiments, referring toFIG.2, the first sun gear98and the second sun gear108may each be independently connected (e.g., connected in parallel) to the low speed rotating assembly68and its low speed shaft66. In other embodiments, however, the second sun gear108may be connected to the low speed rotating assembly68and its low speed shaft66through the first sun gear98. The second sun gear108, for example, may be rotationally fixed to the first sun gear98. In still other embodiments, the first sun gear98may be connected to the low speed rotating assembly68and its low speed shaft66through the second sun gear108. The first sun gear98, for example, may be rotationally fixed to the second sun gear108.

In some embodiments, referring toFIG.2, the low speed rotating assembly68and its low speed shaft66may be connected to the transmission76(seeFIG.1) and, thus, the second propulsor rotor24independent of (e.g., in parallel with) geartrain72. In other embodiments, however, the transmission76and, thus, the second propulsor rotor24may be coupled to the low speed rotating assembly68and its low speed shaft66through the first sun gear98or the second sun gear108, but not though the rest of the first gear system94and the second gear system96. Thus, while power may be transferred from the low speed rotating assembly68to the second propulsor rotor24through the sun gear(s)98and/or108, the output from the geartrain72to the transmission76may still rotate with the low speed rotating assembly68at a common rotational velocity.

In some embodiments, referring toFIG.12, the engine assembly144may also or alternatively include another fluid device174′; e.g., a fluid coupling and/or a fluid damper. The fluid device174′ ofFIG.12, for example, is integrated into the radial stop202. This fluid device174′ is radially outboard of, axially aligned with and circumscribes the outer bearing mount172and the bearing150. Here, the fluid device174′ is axially aligned with the bearing150; however, the present disclosure is not limited to such an exemplary arrangement. The fluid device174′ ofFIG.12is radially engaged with the outer bearing mount172. The fluid device174′ ofFIG.12may have a similar configuration as the fluid device174described above, where features associated with the fluid device174′ are labeled with common identification numbers as the features associated with the fluid device174, except further provided with an apostrophe (′) following the identification number; e.g.,166′,182′,186′,190′ and192′.

In some embodiments, referring toFIG.1, the low speed rotating assembly68may be configured without a compressor rotor. In other embodiments, referring toFIG.13, the low speed rotating assembly68may include a low pressure compressor (LPC) rotor58′ arranged within a low pressure compressor (LPC) section46A of the compressor section46. In such embodiments, the compressor rotor58may be a high pressure compressor (HPC) rotor58within a high pressure compressor (HPC) section46B of the compressor section46.

The engine core26(e.g., seeFIG.1) may have various configurations other than those described above. The engine core26, for example, may be configured with a single spool, with two spools (e.g., seeFIGS.1and12), or with more than two spools. The engine core26may be configured with one or more axial flow compressor sections, one or more radial flow compressor sections, one or more axial flow turbine sections and/or one or more radial flow turbine sections. The engine core26may be configured with any type or configuration of annular, tubular (e.g., CAN), axial flow and/or reverser flow combustor. The present disclosure therefore is not limited to any particular types or configurations of gas turbine engine cores. Furthermore, it is contemplated the engine core26of the present disclosure may drive more than the two propulsor rotors22and24, or a single one of the propulsor rotors22,24and/or one or more other mechanical loads; e.g., electric machines, electric generators, electric motors, etc. The aircraft propulsion system20, for example, may include two or more of the first propulsor rotors22and/or two or more of the second propulsor rotors24. For example, the aircraft propulsion system20ofFIG.14includes multiple second propulsor rotors24rotatably driven by the low speed rotating assembly68. These second propulsor rotors24may rotate about a common axis. Alternatively, each second propulsor rotor24may rotate about a discrete axis where, for example, the second propulsor rotors24are laterally spaced from one another and coupled to the low speed rotating assembly68through a power splitting geartrain208.

While various embodiments of the present disclosure have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the disclosure. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents.