Abstract: A gas turbine engine comprises a housing having an inlet leading to a fan rotor. A bypass door is mounted upstream of the inlet to the fan rotor, and is moveable away from a non-bypass position to a bypass position to selectively bypass boundary layer air vertically beneath the engine. An aircraft is also disclosed.

Abstract: A gas turbine engine comprises a core engine, a fan, a bypass duct and a clutch. The fan is driven by the core engine. The bypass duct is configured to receive airflow from the fan. The clutch links the core engine and the fan. The core comprises a reverse-flow, two-spool gas generator in one embodiment. In another embodiment, the fan is driven by a free turbine aerodynamically powered by the core engine. In one embodiment, the clutch includes reverse gearing to reverse rotational output of the fan. In one embodiment, the clutch and reverse gearing are implemented in an epicyclic gear system.

Abstract: A gas turbine engine includes a main compressor. A tap is fluidly connected downstream of the main compressor. A heat exchanger is fluidly connected downstream of the tap. An auxiliary compressor unit is fluidly connected downstream of the heat exchanger. The auxiliary compressor unit is configured to compress air cooled by the heat exchanger with an overall auxiliary compressor unit pressure ratio between 1.1 and 6.0. An intercooling system for a gas turbine engine is also disclosed.

Abstract: A turbofan engine has an engine case and a gaspath through the engine case. A fan has a circumferential array of fan blades. The engine further has a compressor, a combustor, a gas generating turbine, and a low pressure turbine section. A speed reduction mechanism couples the low pressure turbine section to the fan. A bypass area ratio is greater than about 6.0. The low pressure turbine section airfoil count to bypass area ratio is below about 170.

Abstract: According to an example embodiment, a gas turbine engine assembly includes, among other things, a fan section including a fan, the fan including a plurality of fan blades, a diameter of the fan having a dimension D that is based on a dimension of the fan blades, each fan blade having a leading edge, and a forward most portion on the leading edges of the fan blades in a first reference plane, a turbine section including a high pressure turbine and a low pressure turbine, the low pressure turbine driving the fan, a nacelle including an inlet portion forward of the fan, a forward edge on the inlet portion in a second reference plane, and a length of the inlet portion having a dimension L measured along an engine axis between the first reference plane and the second reference plane. A dimensional relationship of L/D is no more than 0.45.

Abstract: According to an example embodiment, a gas turbine engine assembly includes, among other things, a fan section including a fan, the fan including a plurality of fan blades, a diameter of the fan having a dimension D that is based on a dimension of the fan blades, each fan blade having a leading edge, and a forward most portion on the leading edges of the fan blades in a first reference plane, a geared architecture, a turbine section including a high pressure turbine and a low pressure turbine, the low pressure turbine driving the fan through the geared architecture, a nacelle surrounding the fan, the nacelle including an inlet portion forward of the fan, a forward edge on the inlet portion in a second reference plane, and a length of the inlet portion having a dimension L measured along an engine axis between the first reference plane and the second reference plane. A dimensional relationship of L/D is no more than 0.45.

Abstract: A cross flow fan to be incorporated into an aircraft fuselage comprises an ingestion fan rotor to be positioned in a tail section of an aircraft fuselage to reduce boundary layer air from a top surface of the fuselage and to drive the air away from the top surface, and a drive arrangement for the ingestion fan rotor. An aircraft is also disclosed.

Abstract: A transition duct defining an airflow pathway between a low pressure compressor and a high pressure compressor of a gas turbine engine is disclosed. The transition duct may comprise an inner wall and an outer wall located radially outward of the inner wall with respect to a central axis of the gas turbine engine. It may further comprise a first bend configured to turn the airflow radially inward with respect to the central axis, and a turning vane located at the first bend between the inner wall and the outer wall. The turning vane may be configured to assist the first bend in turning the airflow radially inward.

Abstract: According to an example embodiment, a gas turbine engine assembly includes, among other things, a fan that has a plurality of fan blades. A diameter of the fan has a dimension D that is based on a dimension of the fan blades. Each fan blade has a leading edge. An inlet portion is situated forward of the fan. A length of the inlet portion has a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion. A dimensional relationship of L/D is between about 0.2 and about 0.45.

Abstract: A gas turbine engine comprises a main fan that delivers air into a bypass duct and into a core engine. A heat exchanger is positioned within the bypass duct and receives a fluid to be cooled from a component associated with the gas turbine engine. A heat exchanger fan is positioned to draw air across the heat exchanger and a control for the heat exchanger fan. The control is programmed to stop operation of the fan during certain conditions, and to drive the heat exchanger fan under other conditions. A method of forming a heat exchanger is also disclosed.

Abstract: According to an example embodiment, a gas turbine engine assembly includes, among other things, a fan that has a plurality of fan blades. A diameter of the fan has a dimension D that is based on a dimension of the fan blades. Each fan blade has a leading edge. An inlet portion is situated forward of the fan. A length of the inlet portion has a dimension L between a location of the leading edge of at least some of the fan blades and a forward edge on the inlet portion. A dimensional relationship of L/D is between about 0.2 and 0.45.

Abstract: A gas turbine engine comprises a main compressor section having a downstream most end, and more upstream locations. A turbine section has a high pressure turbine. A tap taps air from at least one of the more upstream locations in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses ng air downstream of the heat exchanger, and delivers air into the high pressure turbine. The heat exchanger has at least two passes, with one of the passes passing air radially outwardly, and a second of the passes returning the air radially inwardly to the compressor. An intercooling system for a gas turbine engine is also disclosed.

Abstract: A gas turbine engine comprises an outer nacelle. A nose cone is spaced radially inward of the outer nacelle. The nose cone defines a particle separator for directing an outer air flow and an inner airflow. The inner airflow is directed through a core inlet to a compressor. The engine further comprises a drive gear system for driving at least one propeller. A variable pitch control system may alter a pitch angle of the at least one propeller. Some of the outer air flow is directed to at least one of the drive gear system and the pitch control system.

Abstract: A gas turbine engine comprises a plurality of fan rotors. A gas generator comprises at least one compressor rotor, at least one gas generator turbine rotor, a combustion section, and a fan drive turbine downstream of at least one gas generator turbine rotor. A shaft is configured to be driven by the fan drive turbine. The shaft engages gears to drive the plurality of fan rotors. A system controls the amount of power supplied to the plurality of fan rotors. A method of operating a gas turbine engine is also disclosed.

Abstract: A fan section for an engine has a fan which rotates about an axis, the fan has an inlet for ingesting ambient air, and a non-axisymmetric nozzle for providing the fan with non-uniform back pressure.

Abstract: A gas turbine engine includes a core engine assembly including a compressor section communicating air to a combustor section where the air is mixed with fuel and ignited to generate a high-energy gas flow that is expanded through a turbine section. The turbine section is coupled to drive the compressor section. A propulsor section aft of the core engine is driven by the turbine section. An exhaust duct routing exhaust gases around the propulsor section. The exhaust duct includes an inlet forward of the propulsor section, an outlet aft of the turbine section and a passageway between the inlet and the outlet. An aircraft and exhaust duct are also disclosed.

Abstract: A gas turbine engine has an inner housing surrounding a compressor, a combustor, and a turbine, with an inlet leading into the compressor, and a cooling sleeve defined radially outwardly of the inlet to the compressor for receiving cooling air radially outward of the compressor inlet. The cooling sleeve extends along a length of the engine, and radially outwardly of the inner housing, with the cooling air in the cooling sleeve being ejected at a downstream end to mix with products of combustion downstream of the turbine. An aircraft is also disclosed.

Abstract: A rotor for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a rotor disk rotatable about an axis and a gas path wall coupled to and radially outward of the rotor disk. The gas path wall bounds a radially inward portion of a gas path. A plurality of rotor spokes are radially intermediate the rotor disk and the gas path wall. The plurality of rotor spokes is circumferentially spaced to define a plurality of cooling channels intermediate the rotor disk and the gas path wall. A thermal barrier coating is disposed on a surface of at least one of the plurality of cooling channels. A method of cooling a rotor assembly is also disclosed.

Abstract: A gas turbine engine comprises a main compressor section having a downstream most end, and more upstream locations. A turbine section has a high pressure turbine. A tap taps air from at least one of the more upstream locations in the compressor section, passes the tapped air through a heat exchanger and then to a cooling compressor. The cooling compressor compresses ng air downstream of the heat exchanger, and delivers air into the high pressure turbine. The heat exchanger has at least two passes, with one of the passes passing air radially outwardly, and a second of the passes returning the air radially inwardly to the compressor. An intercooling system for a gas turbine engine is also disclosed.

Abstract: A fan assembly for a gas turbine engine includes a fan including a plurality of fan blades. Each fan blade extends radially outwardly from a fan hub to a blade tip. The plurality of blade tips define a fan diameter. A nacelle surrounds the fan and defines a fan inlet upstream of the fan, relative to an airflow direction into the fan. The nacelle has a forwardmost edge defining an inlet length from the forwardmost edge to a leading edge of a fan blade of the plurality of fan blades. A ratio of inlet length to fan diameter is between 0.20 and 0.45. A nacelle inner surface defines a nacelle flowpath. The nacelle flowpath has a convex throat portion and a concave diffusion portion between the throat portion and the leading edge of the fan blade at a bottommost portion of the nacelle.