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.

A turbofan gas turbine engine comprises, in axial flow sequence, a heat exchanger module, a fan assembly, a compressor module, and a turbine module. The fan assembly comprises a plurality of fan blades defining a fan diameter (D), and the heat exchanger module comprises a plurality of heat exchanger elements. The heat exchanger module is in fluid communication with the fan assembly by an inlet duct, with the heat exchanger module having an axial length along a central axis between an upstream-most face of the heat exchanger elements and a downstream-most face of the heat exchanger elements. The axial length is in the range of 0.1*D to 5.0*D.

A turbofan gas turbine engine comprises, in axial flow sequence, a heat exchanger module, a fan assembly, a compressor module, and a turbine module. The fan assembly comprises a plurality of fan blades defining a fan diameter (D), and the heat exchanger module comprises a plurality of heat exchanger elements. The heat exchanger module is in fluid communication with the fan assembly by an inlet duct, with the heat exchanger module having an axial length along a central axis between an upstream-most face of the heat exchanger elements and a downstream-most face of the heat exchanger elements. The axial length is in the range of 0.1*D to 5.0*D.

A cooler assembly disposed in and cooled by an air stream according to one embodiment includes a cooler matrix and a fairing. The fairing assembly is disposed generally around the cooler matrix and includes side fairing-housings, first and second side fairing-housings being joined to one another at respective leading and trailing edges, the leading edges partially defining a cooler inlet and the trailing edges partially defining a cooler outlet, the first and second side fairing-housing trailing edges angled transversely toward each other to define a trapezoidal shape for the outlet.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct; a primary fan driven by the turbomachine; and a secondary fan located downstream of the primary fan within the inlet duct. The gas turbine engine defines a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10, wherein the thrust to power airflow ratio is a ratio of an airflow through a bypass passage over the turbomachine plus an airflow through the fan duct to an airflow through the core duct, and wherein the core bypass ratio is a ratio of the airflow through the fan duct to the airflow through the core duct.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct; a primary fan driven by the turbomachine; and a secondary fan located downstream of the primary fan within the inlet duct. The gas turbine engine defines a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10, wherein the thrust to power airflow ratio is a ratio of an airflow through a bypass passage over the turbomachine plus an airflow through the fan duct to an airflow through the core duct, and wherein the core bypass ratio is a ratio of the airflow through the fan duct to the airflow through the core duct.

A gas turbine engine system and method of operating gas turbine engines are provided. The gas turbine engine assembly includes a gas turbine engine includes a power shaft configured to rotate about an axis of rotation. The gas turbine engine assembly also includes a first fan and a second fan coupled to the power shaft coaxially with the gas turbine engine. The gas turbine engine assembly also includes a first fan duct configured to direct a first stream of air to the first fan. The gas turbine engine assembly also includes a second fan duct configured to direct a second stream of air to the second fan. The gas turbine engine assembly also includes an exhaust duct configured to direct a stream of exhaust gases of the gas turbine engine in a direction of the axis of rotation.

A gas turbine engine includes a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order. The turbomachine defines an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct. The primary fan is driven by the turbomachine, and a secondary fan is located downstream of the primary fan within the inlet duct. One or more actuation devices operably associated with the fan duct, the one or more actuation devices actuable to increase or decrease an exit area of the fan duct.

A gas turbine engine includes a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order. The turbomachine defines an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct. The primary fan is driven by the turbomachine, and a secondary fan is located downstream of the primary fan within the inlet duct. One or more actuation devices operably associated with the fan duct, the one or more actuation devices actuable to increase or decrease an exit area of the fan duct.

A gas turbine engine includes a turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct; a primary fan driven by the turbomachine; and a secondary fan located downstream of the primary fan within the inlet duct. The gas turbine engine defines a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10. The thrust to power airflow ratio is a ratio of airflow through a bypass passage over the turbomachine plus airflow through the fan duct to airflow through the core duct. The core bypass ratio is a ratio of airflow through the fan duct to airflow through the core duct. The fan duct includes an exhaust nozzle having a plurality of chevrons disposed at its aft end to define an exhaust outlet.