Abstract: A turbomachine engine includes a core engine having one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections. The turbomachine engine also includes a shaft coupled to the power turbine and characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2. In one aspect, the shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). In another aspect, the shaft has a length L, an outer diameter D, and a ratio of L/D between twelve and thirty-seven.

Abstract: A gas turbine engine includes a compressor rotor shaft assembly, an accessory gearbox, and a bowed-rotor mitigation drive device drivingly coupled with the accessory gearbox. The bowed-rotor mitigation drive device is driven during an engine startup phase so as to induce a mechanical load (mechanical energy) to the bowed-rotor mitigation drive device. The mechanical load (mechanical energy) is retained within the bowed-rotor mitigation drive device during operation of the gas turbine engine. The mechanical load (mechanical energy) retained within the bowed-rotor mitigation drive device is periodically released by the bowed-rotor mitigation drive device in a plurality of periods so as to provide, in each period, a driving force to the accessory gearbox, which provides the driving force to the compressor rotor shaft assembly to periodically rotate the compressor rotor shaft assembly.

Abstract: A turbomachine engine includes a fan section having a fan shaft, and a core engine having one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections. The turbomachine engine includes a low-speed shaft coupled to the power turbine and having a midshaft that extends from a forward bearing to an aft bearing. The low-speed shaft is characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2. The low-speed shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). The turbomachine engine includes a gearbox assembly that couples the fan shaft to the low-speed shaft and characterized by a gearbox assembly mode less than 95% of a midshaft mode of the midshaft or greater than 105% of the midshaft mode.

Abstract: A gas turbine engine including a rotating shaft and a bearing assembly. The bearing assembly is configured to support the rotating shaft. The bearing assembly has a first bearing and a second bearing. The first bearing is configured to support an axial load of the rotating shaft when a forward thrust of the rotating shaft is greater than ten percent. The second bearing is configured to support the axial load of the rotating shaft when a thrust of the rotating shaft is between ten percent forward thrust and ten percent aft thrust, inclusive of the end points.

Abstract: A high-pressure (HP) rotor control system includes an HP rotor and a controller. The HP rotor includes a plurality of rotor blades that rotate about a centerline axis, and a plurality of variable stator vanes (VSVs) that are rotatable about a variable stator vane (VSV) pitch axis. The plurality of VSVs are disposed at an incidence angle. The controller controls the plurality of VSVs to rotate the plurality of VSVs about the VSV pitch axis to change the rotor incidence angle of the plurality of VSVs as the HP rotor approaches a thrust crossover condition.

Abstract: A gas turbine engine including a rotating shaft and a bearing assembly. The bearing assembly is configured to support the rotating shaft. The bearing assembly has a first bearing and a second bearing. The first bearing is configured to support an axial load of the rotating shaft when a forward thrust of the rotating shaft is greater than ten percent. The second bearing is configured to support the axial load of the rotating shaft when a thrust of the rotating shaft is between ten percent forward thrust and ten percent aft thrust, inclusive of the end points.

Abstract: A lubricant supply system for a squeeze film damper. The lubricant supply system includes a fluid passage configured to supply a lubricant to the squeeze film damper of a bearing assembly. The fluid passage includes a first flow path for lubricant into the lubricant supply system and into the squeeze film damper of the bearing assembly and a second flow path for lubricant into the squeeze film damper of the bearing assembly. The lubricant supply system includes a valve assembly configured to allow the fluid passage to move from the first flow path to the second flow path in response to an interruption of the first flow path.

Abstract: A bearing support assembly to support one or more bearings on a shaft. The bearing support assembly includes a bearing support frame configured to be coupled to a static frame, a plurality of ribs connected to the bearing support frame, and a bearing support connected to the plurality of ribs and configured to support a bearing of the one or more bearings. The bearing support assembly has a non-axisymmetric stiffness around a circumference of the bearing support assembly.

Abstract: A gas turbine engine including a rotating shaft and a bearing assembly. The bearing assembly is configured to support the rotating shaft. The bearing assembly has a first bearing and a second bearing. The first bearing is configured to support an axial load of the rotating shaft when a forward thrust of the rotating shaft is greater than ten percent. The second bearing is configured to support the axial load of the rotating shaft when a thrust of the rotating shaft is between ten percent forward thrust and ten percent aft thrust, inclusive of the end points.

Abstract: A gas turbine engine including a rotating shaft and a bearing assembly. The bearing assembly is configured to support the rotating shaft. The bearing assembly has a first bearing and a second bearing. The first bearing is configured to support an axial load of the rotating shaft when a forward thrust of the rotating shaft is greater than ten percent. The second bearing is configured to support the axial load of the rotating shaft when a thrust of the rotating shaft is between ten percent forward thrust and ten percent aft thrust, inclusive of the end points.

Abstract: A turbomachine engine includes a core engine having one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections. The turbomachine engine also includes a shaft coupled to the power turbine and characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2. In one aspect, the shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). In another aspect, the shaft has a length L, an outer diameter D, and a ratio of L/D between twelve and thirty-seven.

Abstract: A turbomachine engine includes a fan section having a fan shaft, and a core engine having one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections. The turbomachine engine includes a low-speed shaft coupled to the power turbine and having a midshaft that extends from a forward bearing to an aft bearing. The low-speed shaft is characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2. The low-speed shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). The turbomachine engine includes a gearbox assembly that couples the fan shaft to the low-speed shaft and characterized by a gearbox assembly mode less than 95% of a midshaft mode of the midshaft or greater than 105% of the midshaft mode.

Abstract: A damping device that includes features for damping bending vibration of a shaft rotating about its axis of rotation and methods for damping bending vibration utilizing the damping device are provided. In one exemplary aspect, the damping device includes a damping disc operatively coupled with a shaft, e.g., of a turbine engine or shaft system. The damping disc is at least partially received within a chamber defined by a housing. The chamber of the housing is configured to receive a damping fluid. When the shaft is rotated about its axis of rotation, the damping disc is movable within the chamber to move the damping fluid such that the damping fluid absorbs bending vibration emitted by the shaft. The damping fluid moved by the damping disc dampens bending vibration emitted by the shaft.

Abstract: A gas turbine engine includes a compressor rotor shaft assembly, an accessory gearbox, and a bowed-rotor mitigation drive device drivingly coupled with the accessory gearbox. The bowed-rotor mitigation drive device is driven during an engine startup phase so as to induce a mechanical load (mechanical energy) to the bowed-rotor mitigation drive device. The mechanical load (mechanical energy) is retained within the bowed-rotor mitigation drive device during operation of the gas turbine engine. The mechanical load (mechanical energy) retained within the bowed-rotor mitigation drive device is periodically released by the bowed-rotor mitigation drive device in a plurality of periods so as to provide, in each period, a driving force to the accessory gearbox, which provides the driving force to the compressor rotor shaft assembly to periodically rotate the compressor rotor shaft assembly.

Abstract: A bearing support assembly to support one or more bearings on a shaft. The bearing support assembly includes a bearing support frame configured to be coupled to a static frame, a plurality of ribs connected to the bearing support frame, and a bearing support connected to the plurality of ribs and configured to support a bearing of the one or more bearings. The bearing support assembly has a non-axisymmetric stiffness around a circumference of the bearing support assembly.

Abstract: A gas turbine engine includes a compressor rotor shaft assembly, an accessory gearbox, and a bowed-rotor mitigation drive device drivingly coupled with the accessory gearbox. The bowed-rotor mitigation drive device is driven during an engine startup phase so as to induce a mechanical load (mechanical energy) to the bowed-rotor mitigation drive device. The mechanical load (mechanical energy) is retained within the bowed-rotor mitigation drive device during operation of the gas turbine engine. The mechanical load (mechanical energy) retained within the bowed-rotor mitigation drive device is periodically released by the bowed-rotor mitigation drive device in a plurality of periods so as to provide, in each period, a driving force to the accessory gearbox, which provides the driving force to the compressor rotor shaft assembly to periodically rotate the compressor rotor shaft assembly.

Abstract: A turbomachine engine includes a fan section having a fan shaft, and a core engine having one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections. The turbomachine engine includes a low-speed shaft coupled to the power turbine and having a midshaft that extends from a forward bearing to an aft bearing. The low-speed shaft is characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2. The low-speed shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). The turbomachine engine includes a gearbox assembly that couples the fan shaft to the low-speed shaft and characterized by a gearbox assembly mode less than 95% of a midshaft mode of the midshaft or greater than 105% of the midshaft mode.

Abstract: A turbomachine engine includes a core engine having one or more compressor sections, one or more turbine sections that includes a power turbine, and a combustion chamber in flow communication with the compressor sections and turbine sections. The turbomachine engine also includes a shaft coupled to the power turbine and characterized by a midshaft rating (MSR) between two hundred (ft/sec)1/2 and three hundred (ft/sec)1/2. In one aspect, the shaft has a redline speed between fifty and two hundred fifty feet per second (ft/sec). In another aspect, the shaft has a length L, an outer diameter D, and a ratio of L/D between twelve and thirty-seven.

Abstract: A lubricant supply system for a squeeze film damper. The lubricant supply system includes a fluid passage configured to supply a lubricant to the squeeze film damper of a bearing assembly. The fluid passage includes a first flow path for lubricant into the lubricant supply system and into the squeeze film damper of the bearing assembly and a second flow path for lubricant into the squeeze film damper of the bearing assembly. The lubricant supply system includes a valve assembly configured to allow the fluid passage to move from the first flow path to the second flow path in response to an interruption of the first flow path.

Abstract: A bearing system is configured to surround a rotor along a circumferential direction corresponding to the rotor. The rotor is extended along an axial direction co-directional to a centerline axis of the rotor. The bearing system includes a body from which a plurality of first support members is each extended, and wherein the plurality of first support members is spaced apart from one another along the circumferential direction. Each first support member includes a first axial support arm extended along the axial direction and a first radial support arm extended from the first axial support arm along a radial direction. The first radial support arm is configured to position a bearing element in contact with a bearing surface at the rotor.