Patent Description:
A turbofan engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-energy exhaust gas flow. The high-energy exhaust gas flow expands through the turbine section to drive the compressor and the fan section.

Electric power for the engine is typically provided by a motor/generator driven through a tower shaft driven by a main engine shaft. Motor/generators and electric motors are typically standalone devices that are coupled to an external accessory gearbox. Alternate motor/generator and motor configurations and placements may provide increased engine efficiencies and accommodate increasing demands for electric power.

<CIT> discloses a gas turbine engine with a duct connecting the bypass airflow to the tailcone, and a cooling air compressor operable within the duct to deliver cooling air to a generator within the tail cone.

<CIT> discloses a gas turbine engine with an electric communication bus that is connected to an electric machine and extends through the flowpath, the electric cables being within a cooling conduit through which lubrication fluid is pumped which acts as a cooling fluid.

<CIT> discloses a turbine engine shutdown temperature control system configured to foster consistent air temperature within cavities surrounding compressor and turbine blade assemblies to eliminate turbine and compressor blade tip rub during warm restarts of gas turbine engines.

From a first aspect of the invention, a cooling system for a gas turbine engine is disclosed according to claim <NUM>.

In various embodiments, the electric fan may be configured to actively cool the plurality of conductive cables. The cooling system may further comprise an external air source in fluid communication with the electric fan. The external air source may be disposed radially outward from a bypass airflow path of the gas turbine engine. The cooling system may further comprise a pylon and a strut, wherein the strut extends from a tail cone to the pylon, wherein the electric motor is disposed in the tail cone, and wherein the conduit extends through the strut. In various embodiments, activating may further comprise increasing a speed of the electric fan. The operations may further comprise opening, by the processor, a vent in fluid communication with an external air source.

From a further aspect of the invention, a method of cooling a plurality of conductive cables in an exhaust section of a gas turbine engine is disclosed according to claim <NUM>.

In various embodiments, the method may further comprise releasing air through an egress of the tail cone. The external air source may be disposed radially outward from a bypass flow path of the gas turbine engine. The flowing air through the conduit may include actively cooling the plurality of conductive cables. The external air source may include a vent or a scoop.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the exemplary embodiments of the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not limitation.

Throughout the present disclosure, like reference numbers denote like elements. Accordingly, elements with like element numbering may be shown in the figures, but may not necessarily be repeated herein for the sake of clarity. Surface shading lines and/or cross-hatching may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

Aft includes the direction associated with the tail (e.g., the back end) of an aircraft, or generally, to the direction of exhaust of a gas turbine engine. Forward includes the direction associated with the intake (e.g., the front end) of a gas turbine engine.

A first component that is "radially outward" of a second component means that the first component is positioned at a greater distance away from a central longitudinal axis of the gas turbine engine. A first component that is "radially inward" of a second component means that the first component is positioned closer to the engine central longitudinal axis than the second component. The terminology "radially outward" and "radially inward" may also be used relative to references other than the engine central longitudinal axis.

With reference to <FIG>, a nacelle <NUM> for a gas turbine engine is illustrated according to various embodiments. Nacelle <NUM> may comprise an inlet <NUM>, a fan cowl <NUM>, and a thrust reverser <NUM>. Nacelle <NUM> may be coupled to a pylon <NUM>. Pylon <NUM> may mount nacelle <NUM>, and a gas turbine engine located within nacelle <NUM>, to an aircraft wing or aircraft body. In various embodiments, an exhaust system <NUM> may extend from the gas turbine engine mounted within nacelle <NUM>.

<FIG> illustrates a cross-sectional view of a gas turbine engine <NUM> located within nacelle <NUM>, in accordance with various embodiments. Gas turbine engine <NUM> may include a core engine <NUM>. Core engine <NUM> may include an inlet section <NUM>, a compressor section <NUM>, a combustor section <NUM>, and a turbine section <NUM>. In operation, a fan <NUM> drives fluid (e.g., air) along a bypass flowpath B while compressor section <NUM> can drive air along a core flow-path C for compression and communication into combustor section <NUM> then expansion through turbine section <NUM>. In various embodiments, core engine <NUM> generally comprises a low speed spool and a high speed spool mounted for rotation about an engine central longitudinal axis A-A'. Low speed spool may generally comprise a shaft that interconnects fan <NUM>, a low pressure compressor <NUM>, and a low pressure turbine <NUM>. The high speed spool may comprise a shaft that interconnects a high pressure compressor <NUM> and high pressure turbine <NUM>. A combustor may be located between high pressure compressor <NUM> and high pressure turbine <NUM>. As used herein, a "high pressure" compressor or turbine experiences a higher pressure than a corresponding "low pressure" compressor or turbine. Although depicted as a turbofan engine <NUM> herein, it should be understood that the concepts described herein are not limited in use to turbofans as the teachings may be applied to other types of engines including turboprop and turboshaft engines. Although core engine <NUM> may be depicted as a two-spool architecture herein, it should be understood that the concepts described herein are not limited in use to two-spool gas turbine engines as the teachings may be applied to other types of engines including engines having more than or less than two spools.

Core engine <NUM> drives fan <NUM> of gas turbine engine <NUM>. The airflow in core flow path C may be compressed by low pressure compressor <NUM> then high pressure compressor <NUM>, mixed and burned with fuel in the combustor section <NUM>, then expanded through high pressure turbine <NUM> and low pressure turbine <NUM>. Turbines <NUM>, <NUM> rotationally drive their respective low speed spool and high speed spool in response to the expansion. Bypass airflow B, driven by fan <NUM>, flows in the aft direction through bypass flow path <NUM>. At least a portion of bypass flow path <NUM> may be defined by nacelle <NUM> and an inner fixed structure (IFS) <NUM>.

An upper bifurcation <NUM> and a lower bifurcation <NUM> may extend radially between the nacelle <NUM> and IFS <NUM> in locations opposite one another. Engine components such as wires and fluids, for example, may be accommodated in upper bifurcation <NUM> and lower bifurcation <NUM>. IFS <NUM> surrounds core engine <NUM> and provides core compartment <NUM>. Various components may be provided in core compartment <NUM> such as fluid conduits and/or compressed air ducts. For example, a portion BCORE of bypass airflow B may flow between core engine <NUM> and IFS <NUM> in core compartment <NUM>. A fan case <NUM> may surround fan <NUM>. Fan case <NUM> may be housed within nacelle <NUM>. Fan case <NUM> may provide a mounting structure for securing gas turbine engine <NUM> to pylon <NUM>, with momentary reference to <FIG>. According to various embodiments, one or more fan exit guide vanes <NUM> may extend radially between core engine <NUM> and fan case <NUM>.

Exhaust system <NUM> is located aft of turbine section <NUM>. Core airflow C flows through core engine <NUM> and is expelled through an exhaust outlet <NUM> of exhaust system <NUM>. Exhaust outlet <NUM> may comprise an aerodynamic tail cone <NUM>. A primary nozzle <NUM> may be located radially outward of tail cone <NUM>. Primary nozzle <NUM> and tail cone <NUM> may define exhaust outlet <NUM>. Exhaust outlet <NUM> provides an exhaust path for core airflow C exiting turbine section <NUM> of core engine <NUM>. A secondary nozzle may be located radially outward of primary nozzle <NUM>. Primary nozzle <NUM> and the secondary nozzle may define an exit flow path for bypass airflow B exiting core compartment <NUM> and/or bypass flow path <NUM>. A plurality of turbine exit guide vanes (TEGVs) <NUM> may be located circumferentially about engine central longitudinal axis A-A' and proximate an aft end <NUM> of low pressure turbine <NUM>.

In various embodiments, an electric motor <NUM> is disposed in tail cone <NUM>. The electric motor <NUM> may be mechanically coupled to a low speed spool in core engine <NUM>. Electric motor <NUM> may comprise an electric generator, an electric motor, a combination of the two, or the like. Electric motor <NUM> may be electrically coupled to a juncture box, or any other electrical device known in the art. The electrical device may be disposed radially outward from IFS <NUM> of gas turbine engine <NUM> in a wing <NUM> of an aircraft the pylon <NUM> of the aircraft, or the like. Conductive cables may extend from the electric motor <NUM> to the electric device external to gas turbine engine <NUM>. The conductive cables (e.g., copper wires or the like) may extend radially outward from electric motor <NUM> through a strut <NUM>, through the pylon <NUM> and to an electrical device in the wing <NUM>, or any other location external to IFS <NUM>. The strut <NUM> extends from the tail cone <NUM> to the IFS <NUM>. The strut may be disposed aft of the aft end <NUM> of low pressure compressor turbine <NUM> and forward of exhaust outlet <NUM>. Due to the conductive cables proximity to exhaust outlet <NUM>, the conductive cables may experience relatively high temperatures from airflow in core airflow path C.

In various embodiments, the conductive cables may be disposed in a conduit <NUM> extending radially outward from tail cone <NUM> through strut <NUM> and into the pylon <NUM>. The conduit <NUM> may be fluidly coupled to an external air source by any method known in the art, such as a scoop, a vent, or the like. The external air source <NUM> may be disposed radially outward from nacelle <NUM>. In this regard, the external air source <NUM> may receive colder temperature air relative to bypass airflow B.

In various embodiments, bleed air from the core airflow path C may be diverted aft of the fan as a cooling source. However, bleed air may increase the mass flow and/or reduce efficiency of gas turbine engine <NUM>. To address this, ambient air may be pulled from external to gas turbine engine <NUM>, which may reduce or eliminate utilizing bleed air for the cooling of conductive power cables. In various embodiments, bypass air from bypass airflow path B may be diverted to act as a cooling source for cooling of conductive cables. However, bypass air may be limited to use while the gas turbine engine <NUM> is in operation. In this regard, bypass air may provide insufficient cooling after engine shutdown, or the like.

Referring now to <FIG>, a schematic view of a conductive cable cooling system <NUM>, in accordance with various embodiments, is illustrated. The conductive cable cooling system <NUM> comprises a plurality of conductive cables <NUM>. The conductive cables <NUM> are extending from an electric motor <NUM> disposed in a tail cone <NUM>. The electric motor <NUM> is operably coupled to a low speed spool <NUM> of a gas turbine engine (e.g., gas turbine engine <NUM> from <FIG>). The conductive cable cooling system <NUM> further comprises a strut <NUM> extending from a radially outer surface <NUM> of tail cone <NUM> to a radially inner surface <NUM> of pylon <NUM>. The strut <NUM> may comprise an outer strut shell <NUM> and an inner strut shell <NUM>. The outer strut shell <NUM> may be exposed to airflow from core airflow path C in <FIG> during operation of the gas turbine engine <NUM>. The conductive cable cooling system <NUM> may further comprise an air seal <NUM> disposed between inner strut shell <NUM> and outer strut shell <NUM>. In this regard, the air seal <NUM> may ensure that the plurality of conductive cables <NUM> are sealed from air from core airflow path C.

In various embodiments, the conductive cable cooling system <NUM> further comprises a conduit <NUM>. The conduit <NUM> may be configured to house the plurality of conductive cables <NUM> through strut <NUM>. The conduit <NUM> may be flexible or rigid. The conduit <NUM> may comprise a woven fiberglass sleeve, or the like. The conduit <NUM> may protect the plurality of conductive cables <NUM> from contacting strut <NUM> during operation of the gas turbine engine <NUM> from <FIG>. The conduit <NUM> may further provide a cooling passageway for cooling air to flow from the external air source <NUM>.

In various embodiments, the conductive cable cooling system <NUM> further comprises an electric fan <NUM> in fluid communication with the conduit <NUM> and a vent <NUM>. The electric fan <NUM> is configured to actively cool the plurality of conductive cables <NUM>. The vent <NUM> may be configured to open or close. The electric fan <NUM> is configured to receive cooling airflow from ambient air (e.g., an external air source from the nacelle, such as external air source <NUM>). The electric fan <NUM> and the vent <NUM> may be electrically coupled to a processor <NUM>. In various embodiments, processor <NUM> is in electrical communication with electric fan <NUM>. The processor <NUM> is configured to activate, increase, or decrease a speed of the electric fan in response to various operation conditions of the gas turbine engine. Similarly, the vent <NUM> may be modulated in response to changes in various operation conditions of gas turbine engine. The processor <NUM> is configured to detect an engine shutdown. In response to the engine shutdown, processor <NUM> commands the vent <NUM> to open and commands the electric fan to activate and begin rotating. In various embodiments, vent <NUM> may already be open at engine shutdown, and the processor may command the electric fan to increase a rotation speed or begin to rotate. In various embodiments, vent <NUM> may be commanded to operate between open and closed during operation in response to a desired airflow desired in conduit <NUM>.

The vent <NUM> may assume a closed configuration, an open configuration (<NUM>% open), and/or a partially open configuration (ranging anywhere between <NUM>% open and <NUM>% open) as commanded by a controller. In various embodiments, the closed configuration may comprise the vent <NUM> being a minimum percent open, which may be set at any desired minimum percent open. For the sake of simplicity, in this disclosure, the minimum percent open for the closed configuration is <NUM>% open. In various embodiments, the vent actuator may cause the vent <NUM> to become more open or less open, at any time before, during, or after operation of the gas turbine engine <NUM> from <FIG> to assume the open configuration, a partially open configuration, and/or the closed configuration.

In various embodiments, processor <NUM> may be integrated into computer systems onboard an aircraft, such as, for example, a full authority digital engine control (FADEC), an engineindicating and crew-alerting system (EICAS), and/or the like. Processor <NUM> may include one or more processors and/or one or more tangible, non-transitory memories and be capable of implementing logic. Each processor can be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

In various embodiments, processor <NUM> may comprise a processor configured to implement various logical operations in response to execution of instructions, for example, instructions stored on a non-transitory, tangible, computer-readable medium. As used herein, the term "non-transitory" is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se.

The processsor <NUM> is configured to control conductive cable cooling system <NUM>. For example, processor <NUM> may be configured to transfer a control signal to electric fan to actively control cooling of the plurality of conductive cables <NUM>. Processor <NUM> may generate and transmit the control signal based on an input received from FADEC or an electronic engine control in response to gas turbine engine shutting down. In this regard, conductive cable cooling system <NUM> may allow for active cooling of the plurality of conductive cables <NUM> after engine shutdown. The excitation control signal may further comprise electronic instructions configured to cause the electric fan <NUM> to rotate and provide cooling air in response to a temperature in conduit <NUM> exceeding a predetermined threshold. For example, a temperature sensor may be disposed in conduit <NUM> in electrical communication with the processor <NUM>. In response to the temperature sensor detecting a conduit temperature above a threshold level, electric fan <NUM> may be active. In various embodiments, processor <NUM> may be configured to transmit a control signal to rotate electric fan <NUM> during operation of gas turbine engine <NUM> from FIG. In this regard, electric fan <NUM> may drive air from external air source <NUM> (e.g., ambient air). The external air source <NUM> may provide colder air relative to bypass airflow, core airflow or the like and/or provide better cooling to the plurality of conductive cables than typic cable cooling systems.

In various embodiments, the cooling air provided by electric fan <NUM> may travel along cooling path D through the pylon <NUM> and strut <NUM> into the tail cone <NUM> and exit out an egress disposed at an aft end of tail cone <NUM>.

Referring now to <FIG>, a method <NUM> of using a conductive cable cooling system <NUM> (from <FIG>) of a gas turbine engine <NUM> (from <FIG>), in accordance with various embodiments, is illustrated. The method <NUM> comprises pulling air from an external source (step <NUM>). The external air source may be exposed to ambient air during operation of the gas turbine engine. The external air source is disposed radially outward from a bypass flow path of the gas turbine engine. The external air source may be exposed to air colder relatively to airflow in the bypass flow path during operation of the gas turbine engine. The external air source may include a vent, a scoop, or the like. In various embodiments, the pulling the air may further comprise pulling the air via an electric fan. The electric fan may be disposed in a conduit in a pylon of an aircraft.

The method <NUM> further comprises flowing the air through the conduit (step <NUM>). The conduit may extend from the pylon of an aircraft through an inner fixed structure and into a tail cone. The tail conduit may be disposed in a strut extending between the tail cone and the inner fixed structure. The conduit may house a plurality of conductive cables. Flowing the air through the conduit may further comprise cooling the plurality of conductive cables disposed in the conduit. The plurality of cables may be coupled to an electric machine disposed in the tail cone.

The method <NUM> may further comprise releasing the air through an egress (step <NUM>). The egress may be disposed at an aft end of the tail cone. The egress may allow the air to be released to the atmosphere. In various embodiments, method <NUM> may allow active cooling of a plurality of conductive cables in electric communication with an electric machine disposed in a tail cone of a gas turbine engine. In this regard, the plurality of cables may be actively cooled after gas turbine engine is no longer operating by activating the fan. This may provide more efficient cooling after engine shutdown. In various embodiments, the method <NUM> may allow active cooling during operation of a gas turbine engine with colder air relative to airflow through a bypass flow path and/or airflow through a core flow path.

Claim 1:
A cooling system (<NUM>) for a gas turbine engine (<NUM>), the cooling system (<NUM>) comprising:
an electric motor (<NUM>);
a conduit (<NUM>, <NUM>);
a plurality of conductive cables (<NUM>) extending from the electric motor (<NUM>), the plurality of conductive cables (<NUM>) disposed at least partially in the conduit (<NUM>); and
a cooling source comprising an electric fan (<NUM>) in fluid communication with the conduit (<NUM>), the electric fan (<NUM>) configured to flow a fluid through the conduit (<NUM>) to cool the plurality of conductive cables (<NUM>) after shutdown of the gas turbine engine (<NUM>);
a processor (<NUM>); and
a non-transitory computer readable storage medium in electronic communication with the processor (<NUM>), the non-transitory computer readable storage medium having instructions stored thereon that, in response to execution by the processor (<NUM>) cause the processor (<NUM>) to perform operations comprising:
detecting, by the processor (<NUM>), a shutdown of the gas turbine engine (<NUM>);
activating, by the processor (<NUM>), the electric fan (<NUM>) to flow the fluid through the conduit (<NUM>), wherein in response to the engine shutdown, the processor (<NUM>) commands a vent (<NUM>) to open and commands the electric fan (<NUM>) to activate and begin rotating.