Abstract: A turbofan engine includes a first spool including a first turbine, and a first tower shaft engaged to the first spool. A second spool includes a second turbine, and a second tower shaft is engaged to the second spool. A superposition gearbox includes a sun gear, a plurality of intermediate gears engaged to the sun gear, and is supported in a carrier and a ring gear circumscribing the intermediate gears. The first tower shaft or the second tower shaft drives one of the intermediate gears. A drive motor is engaged to drive the sun gear, an inner electric motor, a stator disposed radially outside of the inner electric motor, and an outer electric motor disposed radially outside the stator. A first load on the first spool and a second load on the second spool is adjusted by operation of at least one of the inner electric motor and the outer electric motor.

Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, propulsor means, first compression means, second compression means, reduction means for reducing a rotational speed of an output that drives the propulsor means relative to an input, first expansion means, and second expansion means. The reduction means includes an epicyclic gear system with a gear reduction. The gear system is straddle-mounted by first and second bearings on opposite sides of the gear reduction relative to an engine longitudinal axis.

Abstract: An after-fan system for an engine may comprise an after-fan turbine an electrical generator operationally coupled to the after-fan turbine, and an electric motor electrically coupled to the electrical generator. The electrical generator may be configured to generate an electrical current in response to rotation of the after-fan turbine. The electric motor may be configured to generate torque.

Abstract: A turbine engine includes integrated electric machines in the compressor section and the turbine section to supplement power produced from fuel with electric power. The example compressor section includes a compressor electric motor that is coupled to a compressor generator. The example turbine section includes a turbine electric motor that is coupled to the geared architecture to supplement power driving the fan section. A turbine generator provides electric power to the turbine electric motor.

Abstract: A system for bleeding air from a core flow path of a gas turbine engine includes a bleed valve in a bleed air duct configured to receive bleed air from a first entrance point to the core flow path into the bleed air duct; a pressurized air valve in a pressurized air duct configured to receive pressurized air from a second entrance point to the core flow path, the pressurized air at a pressure greater than that received into the first entrance point; an eductor outlet from the pressurized air duct located in the bleed air duct; and a control system operable to control operation of the bleed valve and the pressurized air valve.

Abstract: A turbofan engine includes a first spool including a first turbine, and a first tower shaft engaged to the first spool. A second spool includes a second turbine, and a second tower shaft is engaged to the second spool. A superposition gearbox includes a sun gear, a plurality of intermediate gears engaged to the sun gear, and is supported in a carrier and a ring gear circumscribing the intermediate gears. The first tower shaft or the second tower shaft drives one of the intermediate gears. A drive motor is engaged to drive the sun gear, an inner electric motor, a stator disposed radially outside of the inner electric motor, and an outer electric motor disposed radially outside the stator. A first load on the first spool and a second load on the second spool is adjusted by operation of at least one of the inner electric motor and the outer electric motor.

Abstract: A gas turbine engine turbine has a high pressure turbine configured to rotate with a high pressure compressor as a high pressure spool in a first direction about a central axis and a low pressure turbine configured to rotate with a low pressure compressor as a low pressure spool in the first direction about the central axis. A power density is greater than or equal to about 1.5 and less than or equal to about 5.5 lbf/cubic inches. A fan is connected to the low pressure spool via a speed changing mechanism and rotates in the first direction.

Abstract: A multi-engine system includes a first gas turbine engine that includes a first compressor and a first turbine. The multi-engine system may further include a second gas turbine engine that has a second compressor and a second turbine. Still further, the multi-engine system may include a first crossover cooling network configured to route a first crossover airflow from the first compressor of the first gas turbine engine to the second turbine of the second gas turbine engine and a second crossover cooling network configured to route a second crossover airflow from the second compressor of the second gas turbine engine to the first turbine of the first gas turbine engine.

Abstract: An after-fan system for a gas turbine engine includes a variable pitch fan exit guide vane array. An after-fan turbine downstream of the variable pitch fan exit guide vane array and a control operable to vary a pitch of the variable fan exit guide vane array. A method of generating thrust for a gas turbine engine includes rotating a fan section with an array of fan blades; rotating an after-fan turbine downstream of the fan section; and varying a pitch of a variable fan exit guide vane array downstream of the fan section and upstream of the after-fan turbine.

Abstract: A gas turbine engine includes a propulsor section including a propulsor, a compressor section including a first compressor and a second compressor, a geared architecture, a turbine section including a first turbine and a drive turbine, and a power density of greater than or equal to 4.75 and less than or equal to 5.5 lbf/in3, wherein the power density is a ratio of a thrust provided by the engine to a volume of the turbine section.

Abstract: A disclosed gas turbine engine includes a first electric motor assembly that provides a first drive input for driving fan blades about an axis. A geared architecture is driven by a turbine section and is coupled to the fan section to provide a second drive input for driving the fan blades. A second electric motor assembly is coupled to rotate the geared architecture relative to a fixed structure for controlling a speed of the fan blades provided by a combination of the first drive input and the second drive input.

Abstract: A turbofan engine according to an example of the present disclosure includes, among other things, a fan, a compressor section, a turbine section including a fan drive turbine and a second turbine, an epicyclic gear system with a gear reduction, first and second bearings, and a fan drive shaft interconnecting the gear system and the fan. The fan drive turbine has a first exit area at a first exit point and is rotatable at a first speed. The second turbine has a second exit area at a second exit point and is rotatable at a second speed. A first performance quantity is defined as the product of the first speed squared and the first area. A second performance quantity is defined as the product of the second speed squared and the second area.

Abstract: An after-fan system for an engine may comprise an after-fan turbine an electrical generator operationally coupled to the after-fan turbine, and an electric motor electrically coupled to the electrical generator. The electrical generator may be configured to generate an electrical current in response to rotation of the after-fan turbine. The electric motor may be configured to generate torque.

Abstract: A method of distributing power within a gas turbine engine is disclosed. In various embodiments, the method includes driving a high pressure turbine having a first stage and a second stage with an exhaust stream from a combustor, the first stage connected to a high pressure turbine first stage spool and the second stage connected to a high pressure turbine second stage spool; driving a high pressure compressor connected to a high pressure compressor spool via a differential system, the differential system having a first stage input gear connected to the high pressure turbine first stage spool, a second stage input gear connected to the high pressure turbine second stage spool and an output gear assembly connected to the high pressure compressor spool; and selectively applying an auxiliary input power into at least one of the high pressure compressor spool and the high pressure turbine.

Abstract: A disclosed drive assembly for an auxiliary power unit includes a first drive shaft driven by an auxiliary power unit, a second drive shaft driven by a first electric motor, a differential gear system including a ring gear driven by the second drive shaft, a and planet gears supported within a carrier attached to the ring gear. The first drive shaft and an output shaft are coupled to the planet gears and a generator is driven by the output shaft. The electric motor and the auxiliary power unit combine to drive the output shaft.

Abstract: A section for a gas turbine engine according to an example of the present disclosure includes, among other things, a rotor including a row of blades extending in a radial direction outwardly from a hub. The row of blades deliver flow to a bypass flow path, an intermediate flow path, and a core flow path. A first case surrounds the row of blades to establish the bypass flow path. A first flow splitter divides flow between the bypass flow path and a second duct. An aftmost row of guide vanes extends in the radial direction across the bypass flow path. A second flow splitter radially inboard of the first flow splitter divides flow from the second duct between the intermediate flow path and the core flow path. A bypass port interconnects the intermediate and bypass flow paths.

Abstract: An after-fan system for an engine may comprise an after-fan turbine an electrical generator operationally coupled to the after-fan turbine, and an electric motor electrically coupled to the electrical generator. The electrical generator may be configured to generate an electrical current in response to rotation of the after-fan turbine. The electric motor may be configured to generate torque.

Abstract: A gas turbine engine includes a fan positioned at an engine central longitudinal axis, and a fan drive turbine located at the engine central longitudinal axis and configured to drive rotation of the fan. A gas generator is non-coaxial with the fan drive turbine and operably connected to the fan drive turbine such that exhaust from the gas generator drives rotation of the fan drive turbine. An auxiliary power core is located at the engine central longitudinal axis, and one or more bleed passages connect the gas generator and the auxiliary power core. The one or more bleed passages are configured to selectably combine a bleed airflow from the gas generator and an auxiliary core airflow at the auxiliary power core to direct the combined airflow to the fan drive turbine to increase output of the fan drive turbine.

Abstract: A gas turbine engine includes a propulsor section including a propulsor, a compressor section including a first compressor and a second compressor, a geared architecture, a turbine section including a first turbine and a drive turbine, and a power density of greater than or equal to 4.75 and less than or equal to 5.5 lbf/in3, wherein the power density is a ratio of a thrust provided by the engine to a volume of the turbine section.

Abstract: A gas turbine engine includes a core section including a compressor, a main combustor, and a main turbine. Combustion products from the main combustor drive rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. The gas turbine engine further includes a fan section having a fan rotor located fluidly upstream of the core section. The power turbine is operably connected to the fan rotor to drive rotation of the fan rotor via rotation of the power turbine. The gas turbine engine includes a bleed arrangement having one or more bleed passages configured to divert a bleed airflow from the compressor around the main combustor and main turbine, and reintroduce the bleed airflow into the power turbine.