Patent Description:
Heat management systems aim to manage an engine oil and a fuel at optimal operating temperatures by transferring heat between the engine oil and the fuel. Heat management systems typically transfer heat from the engine oil to the fuel via a fuel oil heat exchanger in order to cool the engine oil and heat the fuel. However, it may not be viable to transfer heat from the engine oil to the fuel in cases where a temperature of the fuel is already above acceptable fuel temperature limits.

To this end, conventional heat management systems may utilise air sourced from within a gas turbine engine (e.g., air downstream of a fan of the gas turbine engine) and air-to-oil heat exchangers to transfer heat from the engine oil to the air in order to reduce/eliminate heat transfer from the engine oil to the fuel. However, the heat added to the air sourced from the gas turbine engine may be regarded as wasted energy. It may be desirable to utilise such wasted energy for potential improvement in an efficiency of the gas turbine engine. Moreover, such conventional heat management systems may necessitate addition of dedicated hardware to the gas turbine engine, which may detrimentally impact other parameters of the gas turbine engine, such as specific fuel consumption, engine noise, and the like. As transferring heat from the engine oil to the air may only be necessary during some phases of a flight in extreme conditions, the addition of the dedicated hardware may render such conventional heat management systems uneconomical.

There remains a need for a heat management system that can provide an integrated solution to the aforementioned deficiencies of the conventional heat management systems. Specifically, there is a need for a heat management system that can improve the efficiency of the gas turbine engine by retaining and utilising the heat from the engine oil between various systems of the aircraft and the gas turbine engine.

United States patent application <CIT> discloses a thermal energy system for use with an aircraft that includes a cooling loop and a cooler. The cooling loop includes a fluid conduit and a pump configured to move fluid through the fluid conduit to transfer heat from a heat source to the fluid in the fluid conduit to cool the heat source. The cooler includes an air-stream heat exchanger located in a duct and is in thermal communication with the fluid conduit to transfer heat between the fluid in the cooling loop and the air passing through the duct.

United States patent <CIT> discloses a propulsion engine for high speed aircraft or missiles including means for supplying a liquid fuel to the engine, a closed fluid circuit comprising an oil lubrication system, another separate closed fluid circuit comprising a hydraulic servo system, and a separate heat exchanger included in each of said fluid circuits. The liquid fuel passes in series, first through the heat exchanger in the oil lubrication system, and then through the heat exchanger in the hydraulic servo system to function as the cooling medium for both heat exchangers.

According to a first aspect there is provided a heat management system for an aircraft powered by a gas turbine engine as set out in claim <NUM>.

The heat management system may utilise the hydraulic fluid to achieve heat transfer between the fuel and the oil. The heat management system may therefore manage the oil and the fuel at optimal operating temperatures when the aircraft undergoes extreme environmental conditions during flight. The heat management system may maintain the temperature of the fuel supplied from the aircraft (i.e., from the fuel tank) above <NUM>, below which fuel-borne water becomes ice, by transferring heat from the oil to the fuel via the hydraulic fluid.

The heat management system may improve an efficiency of the gas turbine engine, as the first heat exchanger may allow heat energy from the oil to be added to the hydraulic fluid and utilised to increase the temperature of the fuel stored in the fuel tank via the hydraulic fluid. Additionally, the heat energy added to the hydraulic fluid from the oil may be utilised for various functions of the aircraft.

Advantageously, the heat management system may provide an integrated solution to temperature management of the oil and the fuel. The heat management system may make use of pre-existing systems (e.g., oil systems, hydraulic systems, and fuel systems) present in the gas turbine engine and the aircraft. As a result, the heat management system may be economical to include in the aircraft and the gas turbine engine.

The heat management system includes a fuel line fluidly coupled to the fuel tank. The heat management system further includes a fuel-oil heat exchanger (FOHE) fluidly coupled to the fuel line and the oil circuit, such that the FOHE brings the fuel and the oil into a heat exchange relationship. The heat management system further includes a low pressure fuel pump configured to supply the fuel from the fuel tank to the FOHE via the fuel line. The heat management system further includes a high pressure fuel pump configured to receive the fuel from the FOHE and supply the fuel to an engine line that is in fluid communication with one or more burners of the gas turbine engine.

The FOHE may transfer heat from the oil to the fuel, thereby preventing fuel-borne water from changing into ice. This may prevent clogging of a fuel filter of the gas turbine engine.

In some embodiments, the heat management system further includes an oil tank storing the oil. The heat management system further includes an oil pump configured to supply the oil from the oil tank to the FOHE. The heat management system further includes a scavenge pump configured to scavenge and supply the oil from the one or more components of the gas turbine engine to the oil tank.

In some embodiments, the oil circuit includes a first oil line fluidly coupled to the oil tank and the FOHE. The oil pump is configured to supply the oil from the oil tank to the FOHE via the first oil line. The oil circuit further includes a second oil line fluidly coupled to the FOHE and the one or more components. The second oil line is configured to supply the oil from the FOHE to the one or more components. The oil circuit further includes a scavenge line fluidly coupled to the one or more components of the gas turbine engine and the oil tank. The scavenge pump is configured to supply the oil from the one or more components to the oil tank via the scavenge line.

In some embodiments, the second heat exchanger is thermally coupled to the first oil line and the at least one of the first hydraulic line and the second hydraulic line.

In some embodiments, the second heat exchanger is thermally coupled to the scavenge line and the at least one of the first hydraulic line and the second hydraulic line.

In some embodiments, the heat management system further includes a bypass line fluidly coupled to the oil circuit, such that the bypass line bypasses the second heat exchanger. The heat management system further includes a valve fluidly coupled to the bypass line and operable to vary a flow of the oil through the bypass line.

In some embodiments, the valve is a variable position valve.

In some embodiments, the heat management system further includes a fuel temperature sensor configured to sense a temperature of the fuel. The heat management system further includes an oil temperature sensor configured to sense a temperature of the oil. The heat management system further includes a controller communicably coupled to each of the fuel temperature sensor and the oil temperature sensor. The controller is configured to control the valve to vary the flow of the oil in the bypass line based on the temperature of the fuel and the temperature of the oil.

In some embodiments, the heat management system further includes a fuel temperature sensor configured to sense a temperature of the fuel. The heat management system further includes an oil temperature sensor configured to sense a temperature of the oil. The heat management system further includes a controller communicably coupled to each of the fuel temperature sensor and the oil temperature sensor. The controller is configured to control the hydraulic pump to control a flow of the hydraulic fluid in the hydraulic circuit based on the temperature of the fuel and the temperature of the oil.

The controller may utilise data from the fuel temperature sensor and the oil temperature sensor to control both the hydraulic pump and the valve in order to maintain the fuel and the oil under their respective acceptable temperature limits.

According to a second aspect there is provided a gas turbine engine and a heat management system for an aircraft. The gas turbine engine comprises an engine core including a turbine, a compressor, and a core shaft connecting the turbine to the compressor. The gas turbine engine further includes a fan located upstream of the engine core. The fan includes a plurality of fan blades. The gas turbine engine further includes a gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft. The heat management system comprises a heat management system according to the first aspect.

In some embodiments, the turbine is a first turbine, the compressor is a first compressor, and the core shaft is a first core shaft. The engine core further includes a second turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor. The second turbine, the second compressor, and the second core shaft are arranged to rotate at a higher rotational speed than the first core shaft.

According to a third aspect there is provided an aircraft including the heat management system according to the first aspect.

The gearbox may be a reduction gearbox (in that the output to the fan is a lower rotational rate than the input from the core shaft). Any type of gearbox may be used. For example, the gearbox may be a "planetary" or "star" gearbox, as described in more detail elsewhere herein. The gearbox may have any desired reduction ratio (defined as the rotational speed of the input shaft divided by the rotational speed of the output shaft), for example greater than <NUM>, for example in the range of from <NUM> to <NUM>, or <NUM> to <NUM>, for example on the order of or at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. The gear ratio may be, for example, between any two of the values in the previous sentence. Purely by way of example, the gearbox may be a "star" gearbox having a ratio in the range of from <NUM> or <NUM> to <NUM>. In some arrangements, the gear ratio may be outside these ranges.

Gas turbine engines in accordance with the present disclosure may have any desired bypass ratio, where the bypass ratio is defined as the ratio of the mass flow rate of the flow through the bypass duct to the mass flow rate of the flow through the core at cruise conditions. In some arrangements the bypass ratio may be greater than (or on the order of) any of the following: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. The bypass ratio may be in an inclusive range bounded by any two of the values in the previous sentence (i.e. the values may form upper or lower bounds), for example in the range of from <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>. The bypass duct may be substantially annular. The bypass duct may be radially outside the engine core. The radially outer surface of the bypass duct may be defined by a nacelle and/or a fan case.

Specific thrust of an engine may be defined as the net thrust of the engine divided by the total mass flow through the engine. At cruise conditions, the specific thrust of an engine described and/or claimed herein may be less than (or on the order of) any of the following: <NUM> Nkg-<NUM>s, <NUM> Nkg-<NUM>s, <NUM> Nkg-<NUM>s, <NUM> Nkg-<NUM>s, <NUM> Nkg-<NUM>s, <NUM> Nkg-<NUM>s or <NUM> Nkg-<NUM>s. The specific thrust may be in an inclusive range bounded by any two of the values in the previous sentence (i.e., the values may form upper or lower bounds), for example in the range of from <NUM> Nkg-<NUM>s to <NUM> Nkg-<NUM>s, or <NUM> Nkg-<NUM>s to <NUM> Nkg-<NUM>s. Such engines may be particularly efficient in comparison with conventional gas turbine engines.

A fan blade and/or aerofoil portion of a fan blade described and/or claimed herein may be manufactured from any suitable material or combination of materials. For example, at least a part of the fan blade and/or aerofoil may be manufactured at least in part from a composite, for example a metal matrix composite and/or an organic matrix composite, such as carbon fibre.

The fan of a gas turbine as described and/or claimed herein may have any desired number of fan blades, for example <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> fan blades.

As used herein, the term "controller" refers a computing device that couples to one or more other devices/circuits, e.g., switching circuits, etc., and which may be configured to communicate with, e.g., to control, such devices/circuits. The controller may include any device that performs logic operations. A controller may include a general processor, a central processing unit, an application specific integrated circuit (ASIC), a digital signal processor, a field programmable gate array (FPGA), a digital circuit, an analogue circuit, a microcontroller, any other type of controller, or any combination thereof.

As used herein, the term "communicably coupled" refers to direct coupling between components and/or indirect coupling between components via one or more intervening components. Such components and intervening components may include, but are not limited to, junctions, communication paths, components, circuit elements, circuits, functional blocks, and/or devices. As an example of indirect coupling, a signal conveyed from a first component to a second component may be modified by one or more intervening components by modifying the form, nature, or format of information in a signal, while one or more elements of the information in the signal are nevertheless conveyed in a manner than can be recognized by the second component.

As used herein, the terms "first" and "second" are used as identifiers. Therefore, such terms should not be construed as limiting of this disclosure. The terms "first" and "second" when used in conjunction with a feature or an element can be interchanged throughout the embodiments of this disclosure.

As used herein, "at least one of A and B" should be understood to mean "only A, only B, or both A and B.

The engine core <NUM> comprises, in axial flow series, a low pressure compressor <NUM>, a high pressure compressor <NUM>, combustion equipment <NUM>, a high pressure turbine <NUM>, a low pressure turbine <NUM>, and a core exhaust nozzle <NUM>.

The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines <NUM>, <NUM> before being exhausted through the core exhaust nozzle <NUM> to provide some propulsive thrust.

Note that the terms "low pressure turbine" and "low pressure compressor" as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e., not including the fan <NUM>) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft <NUM> with the lowest rotational speed in the engine (i.e., not including the gearbox output shaft that drives the fan <NUM>).

By way of further example, the connections (such as the linkages <NUM>, <NUM> in the <FIG> example) between the gearbox <NUM> and other parts of the engine <NUM> (such as the input shaft <NUM>, the output shaft, and the fixed structure <NUM>) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example, between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the disclosure is not limited to the exemplary arrangement of <FIG>.

Optionally, the gearbox may drive additional and/or alternative components (e.g., the intermediate pressure compressor and/or a booster compressor).

Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in <FIG> has a split flow nozzle <NUM>, <NUM> meaning that the flow through the bypass duct <NUM> has its own nozzle <NUM> that is separate to and radially outside the core exhaust nozzle <NUM>. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct <NUM> and the flow through the core <NUM> are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine <NUM> may not comprise a gearbox <NUM>.

As discussed above, in some embodiments, the gas turbine engine <NUM> may include the engine core <NUM> including the turbine <NUM>, the compressor <NUM>, and the core shaft <NUM> connecting the turbine <NUM> to the compressor <NUM>. The gas turbine engine <NUM> may further include the fan <NUM> located upstream of the engine core <NUM>. The fan <NUM> may include a plurality of fan blades. The gas turbine engine <NUM> may further include the gearbox <NUM> that receives an input from the core shaft <NUM> and outputs drive to the fan <NUM> so as to drive the fan <NUM> at a lower rotational speed than the core shaft <NUM>. In some embodiments, the turbine may be a first turbine <NUM>, the compressor may be a first compressor <NUM>, and the core shaft may be a first core shaft <NUM>. The engine core <NUM> may further include a second turbine <NUM>, a second compressor <NUM>, and a second core shaft <NUM> connecting the second turbine <NUM> to the second compressor <NUM>. The second turbine <NUM>, the second compressor <NUM>, and the second core shaft <NUM> may be arranged to rotate at a higher rotational speed than the first core shaft <NUM>.

<FIG> shows a heat management system <NUM> for an aircraft (not shown) powered by the gas turbine engine <NUM> (shown in <FIG>) in accordance with an embodiment of the present disclosure.

The heat management system <NUM> includes a fuel tank <NUM>. In some embodiments, the fuel tank <NUM> may be an aircraft wing fuel tank. In other words, in some embodiments, the aircraft may include a wing, and the fuel tank <NUM> may be disposed within the wing.

The fuel tank <NUM> stores a fuel <NUM>. The fuel <NUM> may include any fuel that is suitable for combustion by the gas turbine engine <NUM> (shown in <FIG>). The fuel <NUM> may be delivered to the combustion equipment <NUM> (shown in <FIG>) of the gas turbine engine <NUM>, where the fuel <NUM> is mixed with air and the mixture is combusted.

The heat management system <NUM> further includes a first heat exchanger <NUM>. The first heat exchanger <NUM> is thermally coupled to the fuel tank <NUM>. The first heat exchanger <NUM> may enable transfer of heat to or from the fuel <NUM> stored in the fuel tank <NUM>.

The heat management system <NUM> further includes a hydraulic pump <NUM> for circulating a hydraulic fluid <NUM> for hydraulically actuating one or more hydraulic components (not shown) of the aircraft. The hydraulic fluid <NUM> may be used to drive, for example, hydraulic actuators, landing gear, and other hydraulic components of the aircraft. The hydraulic fluid <NUM> is depicted by arrows in <FIG>. The arrows depicting the hydraulic fluid <NUM> further show a flow direction of the hydraulic fluid <NUM>.

The hydraulic pump <NUM> may include, for example, a variable displacement pump, such as a vane pump, a gear pump (e.g., a twin pinion gear pump), a piston pump, or any other suitable fixed or variable displacement pump. In some embodiments, the hydraulic pump <NUM> may be driven by an accessory gearbox <NUM>. The accessory gearbox <NUM> may be driven by the gas turbine engine <NUM> (shown in <FIG>). In the context of the present disclosure, the term "accessory gearbox" refers to a gearbox that is connected to some equipment or accessories of the gas turbine engine <NUM>, such as, one or more electrical generators, fuel pumps, oil pumps, a starter motor, and the like.

The heat management system <NUM> further includes a hydraulic circuit <NUM>. The hydraulic circuit <NUM> includes a first hydraulic line <NUM> fluidly coupled to the first heat exchanger <NUM> and the hydraulic pump <NUM>. The hydraulic circuit <NUM> further includes a second hydraulic line <NUM> fluidly coupled to the first heat exchanger <NUM> and the hydraulic pump <NUM>. Each of the first hydraulic line <NUM> and the second hydraulic line <NUM> may include a suitable configuration of piping, couplers, and the like. While not illustrated in <FIG>, the heat management system <NUM> may further include a hydraulic reservoir that stores the hydraulic fluid <NUM>. The hydraulic reservoir may be fluidly coupled to the hydraulic circuit <NUM>.

The hydraulic pump <NUM> receives the hydraulic fluid <NUM> from the first heat exchanger <NUM> via the first hydraulic line <NUM>. Further, the hydraulic pump <NUM> supplies the hydraulic fluid <NUM> to the first heat exchanger <NUM> via the second hydraulic line <NUM>, such that the first heat exchanger <NUM> brings the hydraulic fluid <NUM> and the fuel <NUM> into a heat exchange relationship. The first heat exchanger <NUM> may therefore enable heat exchange or heat transfer between the hydraulic fluid <NUM> and the fuel <NUM>.

In some embodiments, the heat management system <NUM> may further include a recirculation device (not shown) configured to recirculate the fuel <NUM> within the fuel tank <NUM>. For example, the recirculation device may include a low-pressure pump (e.g., a gear pump) configured to recirculate the fuel <NUM> within the fuel tank <NUM>. The recirculation device may ensure that the temperature of the fuel <NUM> remains uniform in the fuel tank <NUM>. In other words, the recirculation device may prevent the fuel <NUM> from having a high localised temperature. The recirculation device may further improve heat transfer between the hydraulic fluid <NUM> and the fuel <NUM>.

The heat management system <NUM> further includes an oil circuit <NUM> for circulating an oil <NUM> to lubricate one or more components <NUM> (shown in <FIG>) of the gas turbine engine <NUM> (shown in <FIG>) requiring lubrication. The oil circuit <NUM> is partially shown in <FIG> for illustrative purposes. Further, the oil <NUM> is depicted by arrows in <FIG>. The arrows depicting the oil <NUM> further show a flow direction of the oil <NUM>. In the context of the present disclosure, the term "oil" refers broadly to lubricants, such as oil-based and/or synthetic-based lubricants. The terms "oil" and "lubricant" are interchangeable herein.

The heat management system <NUM> further includes a second heat exchanger <NUM> thermally coupled to the oil circuit <NUM> and at least one of the first hydraulic line <NUM> and the second hydraulic line <NUM>, such that the second heat exchanger <NUM> brings the hydraulic fluid <NUM> and the oil <NUM> into a heat exchange relationship, thereby allowing heat transfer between the fuel <NUM> and the oil <NUM> via the hydraulic fluid <NUM>.

Each of the first heat exchanger <NUM> and the second heat exchanger <NUM> may include, but is not limited to, a shell and tube heat exchanger, a plate heat exchanger, and so forth.

The heat management system <NUM> may utilise the hydraulic fluid <NUM> to achieve heat transfer between the fuel <NUM> and the oil <NUM>. The heat management system <NUM> may therefore manage the oil <NUM> and the fuel <NUM> at optimal operating temperatures when the aircraft undergoes extreme environmental conditions during flight. The heat management system <NUM> may maintain the temperature of the fuel <NUM> supplied from the aircraft (i.e., from the fuel tank <NUM>) above <NUM>, below which fuel-borne water becomes ice, by transferring heat from the oil <NUM> to the fuel <NUM> via the hydraulic fluid <NUM>.

Furthermore, the heat management system <NUM> may improve an efficiency of the gas turbine engine <NUM>, as the first heat exchanger may allow heat energy from the oil <NUM> to be added to the hydraulic fluid <NUM> and utilised to increase the temperature of the fuel <NUM> stored in the fuel tank <NUM> via the hydraulic fluid <NUM>. Additionally, the heat energy added to the hydraulic fluid <NUM> from the oil <NUM> may be utilised for various functions of the aircraft.

Advantageously, the heat management system <NUM> may provide an integrated solution to temperature management of the oil <NUM> and the fuel <NUM>. The heat management system <NUM> may make use of pre-existing systems (e.g., oil systems, hydraulic systems, and fuel systems) present in the gas turbine engine <NUM> (shown in <FIG>) and the aircraft. As a result, the heat management system <NUM> may be economical to include in the aircraft and the gas turbine engine <NUM>.

The heat management system <NUM> may further include various temperature sensors in order to maintain the fuel <NUM>, the hydraulic fluid <NUM>, and the oil <NUM> at the optimum operating temperatures.

Specifically, the heat management system <NUM> may further include a fuel temperature sensor <NUM> configured to sense the temperature of the fuel <NUM>. The fuel temperature sensor <NUM> shown in <FIG> is disposed in thermal communication with the fuel <NUM> stored in the fuel tank <NUM>, and therefore may sense the temperature of the fuel <NUM> in the fuel tank <NUM>. It may be noted that the heat management system <NUM> may include a plurality of fuel temperature sensors <NUM> disposed at a respective plurality of positions on a fuel line to sense respective temperatures of the fuel <NUM> at the respective plurality of positions of the plurality of fuel temperature sensors <NUM>.

The heat management system <NUM> may further include an oil temperature sensor <NUM> configured to sense the temperature of the oil <NUM>. It may be noted that the heat management system <NUM> may include a plurality of oil temperature sensors <NUM> disposed at a respective plurality of positions on an oil line to sense respective temperatures of the oil <NUM> at the respective plurality of positions of the plurality of oil temperature sensors <NUM>.

The heat management system <NUM> may further include a hydraulic fluid temperature sensor <NUM> configured to sense the temperature of the hydraulic fluid <NUM>. While not illustrated in <FIG>, the heat management system <NUM> may include a plurality of hydraulic fluid temperature sensors <NUM> disposed at a respective plurality of positions on the first hydraulic line <NUM> and the second hydraulic line <NUM> to sense respective temperatures of the hydraulic fluid <NUM> at the respective plurality of positions of the plurality of hydraulic fluid temperature sensors <NUM>.

The fuel temperature sensor <NUM>, the hydraulic fluid temperature sensor <NUM>, and the oil temperature sensor <NUM> may include, for example, thermocouples, resistive temperature sensors, and the like. The heat management system <NUM> may utilise temperature data received from the fuel temperature sensor <NUM>, the hydraulic fluid temperature sensor <NUM>, and the oil temperature sensor <NUM> to maintain the fuel <NUM>, the hydraulic fluid <NUM>, and the oil <NUM> at the optimal operating temperatures.

<FIG> shows a schematic block diagram of the heat management system <NUM> with some elements thereof not shown for illustrative purposes.

Referring to <FIG> and <FIG>, the heat management system <NUM> may further include a controller <NUM>. The controller <NUM> may include a full authority digital electronic computer (FADEC), electronic engine controller (EEC), engine control unit (ECU), Engine Health Monitoring Unit or Engine Monitoring Unit (EHM or EMU), and/or any other computing device or system. The controller <NUM> may include a processor (e.g., any type of processor, such as a multi-core processor or processing/controlling circuit, digital signal processor, etc.), a memory device that are combinations of read-only memory and random access memory, or other data storage devices, and the like.

The controller <NUM> may be communicably coupled to each of the fuel temperature sensor <NUM> and the oil temperature sensor <NUM>. The controller <NUM> may further be communicably coupled to the hydraulic fluid temperature sensor <NUM>. The controller <NUM> may determine the temperature of the fuel <NUM> via the fuel temperature sensor <NUM>, the temperature of the hydraulic fluid <NUM> via the hydraulic fluid temperature sensor <NUM>, and the temperature of oil <NUM> via the oil temperature sensor <NUM>.

The controller <NUM> may be communicably coupled to the hydraulic pump <NUM>. The controller <NUM> may control the hydraulic pump <NUM> to vary a flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM>. Specifically, the controller <NUM> may be configured to control the hydraulic pump <NUM> to control the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM> based on the temperature of the fuel <NUM> and the temperature of the oil <NUM>.

For example, the controller <NUM> may control the hydraulic pump <NUM> to reduce the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM>. The reduction in the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM> may increase a rate of heat exchange between the hydraulic fluid <NUM> and the oil <NUM>, thereby increasing both a cooling rate of the oil <NUM> and a heating rate of the hydraulic fluid <NUM>. The reduction in the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM> may further reduce a rate of heat exchange between the hydraulic fluid <NUM> and the fuel <NUM>, thereby reducing a heating rate of the fuel <NUM>. The controller <NUM> may reduce the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM>, for example, if the temperature of the oil <NUM> is above a threshold oil temperature in order to reduce the temperature of the oil <NUM> below the threshold oil temperature.

Alternatively, the controller <NUM> may control the hydraulic pump <NUM> to increase the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM>. The increase in the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM> may reduce the rate of heat exchange between the hydraulic fluid <NUM> and the oil <NUM>, thereby reducing both the cooling rate of the oil <NUM> and the heating rate of the hydraulic fluid <NUM>. The increase in the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM> may further increase the rate of heat exchange between the hydraulic fluid <NUM> and the fuel <NUM>, thereby increasing the heating rate of the fuel <NUM>. The controller <NUM> may increase the flow of the hydraulic fluid <NUM> in the hydraulic circuit <NUM>, for example, if the temperature of the hydraulic fluid <NUM> is above a threshold hydraulic fluid temperature in order to reduce the temperature of the hydraulic fluid <NUM> below the threshold hydraulic fluid temperature.

The heat management system <NUM> may further include a bypass line <NUM> fluidly coupled to the oil circuit <NUM>, such that the bypass line <NUM> bypasses the second heat exchanger <NUM>. The heat management system <NUM> may further include a valve <NUM> fluidly coupled to the bypass line <NUM> and operable to vary a flow of the oil <NUM> through the bypass line <NUM>. In other words, the valve <NUM> may be controlled to vary the flow of oil <NUM> through the second heat exchanger <NUM> and the bypass line <NUM>.

In some embodiments, the valve <NUM> may be an on/off valve. In other words, the valve <NUM> may have an on state in which the valve <NUM> allows unimpeded flow of the oil <NUM> through the bypass line <NUM>, such that the oil <NUM> bypasses the second heat exchanger <NUM>. The valve <NUM> may further have an off state in which the valve <NUM> prevents flow of the oil <NUM> through the bypass line <NUM>, such that that the oil <NUM> passes through the second heat exchanger <NUM>. The on/off valve may operate based on a pressure of the oil <NUM>. In such embodiments, the heat management system <NUM> may passively control the valve <NUM> based on the pressure of the oil <NUM>.

In some other embodiments, the valve <NUM> may be a variable position valve. In other words, the valve <NUM> may be a control valve. The valve <NUM> may include a valve body, an actuator, and a positioner, body assembly, and trim parts. In such embodiments, the valve <NUM> may enable precise control of the flow of the oil <NUM> in the bypass line <NUM>. Further, the valve <NUM> may be controlled by the controller <NUM>. Specifically, the valve <NUM> may be communicably coupled to the controller <NUM>. The controller <NUM> may be configured to control the valve <NUM> to vary the flow of the oil <NUM> in the bypass line <NUM> based on the temperature of the fuel <NUM> and the temperature of the oil <NUM>. For example, the controller <NUM> may open the valve <NUM>, such that the oil <NUM> substantially bypasses the second heat exchanger <NUM> in order to reduce or prevent heat transfer between the oil <NUM> and the hydraulic fluid <NUM>. The controller <NUM> may open the valve <NUM>, for example, in case the temperature of the hydraulic fluid <NUM> is greater than acceptable hydraulic fluid temperature limits. Alternatively, the controller <NUM> may close the valve <NUM>, such that the oil <NUM> substantially passes through the second heat exchanger <NUM> in order to increase heat transfer between the oil <NUM> and the hydraulic fluid <NUM>. The controller <NUM> may close the valve <NUM>, for example, in case the temperature of the oil <NUM> is greater than acceptable oil temperature limits.

Therefore, the controller <NUM> may control both the hydraulic pump <NUM> and the valve <NUM> in order to maintain the fuel <NUM>, the hydraulic fluid <NUM>, and the oil <NUM> under their respective acceptable temperature limits.

In the illustrated embodiment of <FIG>, the heat management system <NUM> includes a plurality of second heat exchangers <NUM>, more specifically, a pair of second heat exchangers <NUM>. One of the pair of second heat exchangers <NUM> is thermally coupled to the oil circuit <NUM> and the first hydraulic line <NUM>, and the other of the pair of second heat exchangers <NUM> is thermally coupled to the oil circuit <NUM> and the second hydraulic line <NUM>. The heat management system <NUM> illustrated in <FIG> further includes a plurality of bypass lines <NUM> and a plurality of valves <NUM> corresponding to the plurality of second heat exchangers <NUM>.

While not illustrated in <FIG>, in some embodiments, the heat management system <NUM> may include a single second heat exchanger <NUM> thermally coupled to the oil circuit <NUM>, and the first hydraulic line <NUM> or the second hydraulic line <NUM>. Moreover, in some embodiments, the heat management system <NUM> may include a single second heat exchanger <NUM> thermally coupled to each of the first hydraulic line <NUM> and the second hydraulic line <NUM>, and the oil circuit <NUM>.

<FIG> shows a schematic diagram of a portion of the heat management system <NUM> in accordance with an embodiment of the present disclosure. Some elements of the heat management system <NUM> are not shown in <FIG> for illustrative purposes.

The heat management system <NUM> includes a fuel line <NUM> fluidly coupled to the fuel tank <NUM>. The fuel line <NUM> may be configured to transport the fuel <NUM> from the fuel tank <NUM> to an engine line <NUM> that is in fluid communication with one or more burners <NUM> (schematically depicted by a block in <FIG>) of the gas turbine engine <NUM>. The combustion equipment <NUM> (shown in <FIG>) may include the one or more burners <NUM>.

The heat management system <NUM> includes a fuel-oil heat exchanger (FOHE) <NUM> fluidly coupled to the fuel line <NUM> and the oil circuit <NUM>, such that the FOHE <NUM> brings the fuel <NUM> and the oil <NUM> into a heat exchange relationship. The FOHE <NUM> may enable heat exchange between the fuel <NUM> and the oil <NUM> before the fuel <NUM> is supplied to the one or more burners <NUM>. The FOHE <NUM> may include, but is not limited to, a shell and tube heat exchanger, a plate heat exchanger, and so forth.

The heat management system <NUM> includes a low pressure fuel pump <NUM> configured to supply the fuel <NUM> from the fuel tank <NUM> to the FOHE <NUM> via the fuel line <NUM>. The heat management system <NUM> includes a high pressure fuel pump <NUM> configured to receive the fuel <NUM> from the FOHE <NUM> and supply the fuel <NUM> to the engine line <NUM> that is in fluid communication with the one or more burners <NUM> of the gas turbine engine <NUM>.

The heat management system <NUM> may further include a filter <NUM> fluidly disposed between the FOHE <NUM> and the high pressure fuel pump <NUM>. The filter <NUM> may filter the fuel <NUM> received from the FOHE <NUM> before it is supplied to the one or more burners <NUM>. The FOHE <NUM> may transfer heat from the oil <NUM> to the fuel <NUM>, such that the temperature of the fuel <NUM> is increased above a predetermined temperature in order to prevent formation of ice, thereby preventing a blockage of the filter <NUM>.

The heat management system <NUM> may further include an oil tank <NUM>. The oil tank <NUM> may store the oil <NUM>. The oil tank <NUM> may include a deaerator to remove air and other gases from the oil <NUM> stored therein. The heat management system <NUM> may further include an oil pump <NUM> configured to supply the oil <NUM> from the oil tank <NUM> to the FOHE <NUM>. The heat management system <NUM> may further include a scavenge pump <NUM> configured to scavenge and supply the oil <NUM> from the one or more components <NUM> of the gas turbine engine <NUM> to the oil tank <NUM>. The heat management system <NUM> may therefore circulate the oil <NUM> between the oil tank <NUM> and the one or more components <NUM>.

Specifically, the oil circuit <NUM> may include a first oil line <NUM> fluidly coupled to the oil tank <NUM> and the FOHE <NUM>. The oil pump <NUM> may be configured to supply the oil <NUM> from the oil tank <NUM> to the FOHE <NUM> via the first oil line <NUM>. The oil circuit <NUM> may further include a second oil line <NUM> fluidly coupled to the FOHE <NUM> and the one or more components <NUM>. The second oil line <NUM> may be configured to supply the oil <NUM> from the FOHE <NUM> to the one or more components <NUM>. The oil circuit <NUM> may further include a scavenge line <NUM> fluidly coupled to the one or more components <NUM> of the gas turbine engine <NUM> and the oil tank <NUM>. The scavenge pump <NUM> may be configured to supply the oil <NUM> from the one or more components <NUM> to the oil tank <NUM> via the scavenge line <NUM>.

Each of the low pressure fuel pump <NUM>, the high pressure fuel pump <NUM>, the oil pump <NUM>, and the scavenge pump <NUM> may include, for example, a variable displacement pump, such as a vane pump, a gear pump (e.g., a twin pinion gear pump), a piston pump, or any other suitable fixed or variable displacement pump.

The one or more components <NUM> requiring lubrication may include, for example, bearings, turbo machinery, a gearbox, such as a power gear box (PGB), and the like.

As shown in <FIG>, the second heat exchanger <NUM> may be thermally coupled to the oil circuit <NUM> at different locations. The second heat exchanger <NUM> is schematically represented at the different locations by dashed lines.

In some embodiments, the second heat exchanger <NUM> may be thermally coupled to the first oil line <NUM> and the at least one of the first hydraulic line <NUM> and the second hydraulic line <NUM> (shown in <FIG>). In such embodiments, the heat transfer from the oil <NUM> to the fuel <NUM> may be reduced, such that a rise in the temperature of fuel <NUM> is not excessive.

In some embodiments, the second heat exchanger <NUM> may be thermally coupled to the scavenge line <NUM> and the at least one of the first hydraulic line <NUM> and the second hydraulic line <NUM>.

In the illustrated embodiment of <FIG>, the oil circuit <NUM> includes a plurality of scavenge lines <NUM> fluidly coupled to the one or more components <NUM> and a plurality of scavenge pumps <NUM> corresponding to the plurality of scavenge lines <NUM>. The plurality of scavenge lines <NUM> may converge to a combined scavenge line <NUM>. In some embodiments, the second heat exchanger <NUM> may be thermally coupled to the combined scavenge line <NUM> and the at least one of the first hydraulic line <NUM> and the second hydraulic line <NUM> (shown in <FIG>).

The second heat exchanger <NUM> may perform adequately considering aeration of the oil <NUM> that is scavenged via the scavenge line <NUM> and the combined scavenge line <NUM>. Thus, the heat management system <NUM> may operate effectively if the second heat exchanger <NUM> is located at any of the different locations described above.

Moreover, the second heat exchanger <NUM> in the different locations described above may ensure that a difference between the temperature of the oil <NUM> and the temperature of hydraulic fluid <NUM> remains below a predetermined temperature difference to minimise a risk of deterioration of the hydraulic fluid <NUM>.

Claim 1:
A heat management system (<NUM>) for an aircraft powered by a gas turbine engine (<NUM>), the heat management system (<NUM>) comprising:
(a) a fuel tank (<NUM>) storing a fuel (<NUM>);
(b) a first heat exchanger (<NUM>) thermally coupled to the fuel tank (<NUM>);
(c) a hydraulic pump (<NUM>) for circulating a hydraulic fluid (<NUM>) for hydraulically actuating one or more hydraulic components of the aircraft;
(d) a hydraulic circuit (<NUM>) comprising:
a first hydraulic line (<NUM>) fluidly coupled to the first heat exchanger (<NUM>) and the hydraulic pump (<NUM>), wherein the hydraulic pump (<NUM>) receives the hydraulic fluid (<NUM>) from the first heat exchanger (<NUM>) via the first hydraulic line (<NUM>); and
a second hydraulic line (<NUM>) fluidly coupled to the first heat exchanger (<NUM>) and the hydraulic pump (<NUM>), wherein the hydraulic pump (<NUM>) supplies the hydraulic fluid (<NUM>) to the first heat exchanger (<NUM>) via the second hydraulic line (<NUM>), such that the first heat exchanger (<NUM>) brings the hydraulic fluid (<NUM>) and the fuel (<NUM>) into a heat exchange relationship;
(e) an oil circuit (<NUM>) for circulating an oil (<NUM>) to lubricate one or more components (<NUM>) of the gas turbine engine (<NUM>) requiring lubrication; and
(f) a second heat exchanger (<NUM>) thermally coupled to the oil circuit (<NUM>) and at least one of the first hydraulic line (<NUM>) and the second hydraulic line (<NUM>), such that the second heat exchanger (<NUM>) brings the hydraulic fluid (<NUM>) and the oil (<NUM>) into a heat exchange relationship, thereby allowing heat transfer between the fuel (<NUM>) and the oil (<NUM>) via the hydraulic fluid (<NUM>);
characterised in that the heat management system has
a fuel line (<NUM>) fluidly coupled to the fuel tank (<NUM>);
a fuel-oil heat exchanger (FOHE) (<NUM>) fluidly coupled to the fuel line (<NUM>) and the oil circuit (<NUM>), such that the FOHE (<NUM>) brings the fuel (<NUM>) and the oil (<NUM>) into a heat exchange relationship;
a low pressure fuel pump (<NUM>) configured to supply the fuel (<NUM>) from the fuel tank (<NUM>) to the FOHE (<NUM>) via the fuel line (<NUM>); and
a high pressure fuel pump (<NUM>) configured to receive the fuel (<NUM>) from the FOHE (<NUM>) and supply the fuel (<NUM>) to an engine line (<NUM>) that is in fluid communication with one or more burners (<NUM>) of the gas turbine engine (<NUM>).