Method and system for reducing temperature difference across aircraft

Abstract

Methods and systems for reducing temperature differences across an aircraft. The system includes an exterior of the aircraft. The exterior of the aircraft includes a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature to define an initial temperature difference. A fluid circuit containing a working fluid is coupled to the first external panel and the second external panel such that heat is transferred from the first external panel to the working fluid to reduce a first initial temperature of the first external panel to a first altered temperature and heat the working fluid. The heated working fluid circulates from the first external panel and is used to heat the second external panel to a second altered temperature greater than the second initial temperature.

Description

Background Art

[0001] Aircraft traveling in the atmosphere at a flight speed of at least Mach 3 may experience aerodynamic heating of the aircraft's exterior surfaces. Aerodynamic heating may cause the aircraft's exterior surfaces to reach high temperatures, and therefore, these types of aircraft may be designed using materials suitable for the high temperatures associated with flight speeds of at least Mach 3. However, at flight speeds of at least Mach 3, different locations on the aircraft's exterior surfaces may reach different temperatures, which may result in thermal deformation of the aircraft's fuselage and / or increase the fuel cooling requirements of the thermally balanced aircraft. Summary of the invention

[0002] Therefore, there is a need to develop methods and systems for reducing temperature differences between different locations outside an aircraft.

[0003] The present disclosure provides a system for reducing the temperature difference across an aircraft traveling at a flight speed of at least Mach 3. The system includes an exterior of the aircraft. The exterior of the aircraft includes a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature. The first initial temperature is greater than the second initial temperature. The temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference. The system also includes a fluid circuit, which is configured to contain a working fluid. The fluid circuit is coupled to the first exterior panel and the second exterior panel so that heat is transferred from the first exterior panel to the working fluid to reduce the first initial temperature of the first exterior panel to a first change temperature and heat the working fluid. The heated working fluid circulates from the first exterior panel and is used to heat the second exterior panel to a second change temperature, which is greater than the second initial temperature. The temperature difference between the first change temperature and the second change temperature defines an auxiliary temperature difference, which is less than the initial temperature difference.

[0004] The present disclosure also provides a method for reducing the temperature difference across the exterior of an aircraft. The aircraft is propelled at a flight speed of at least Mach 3. By propelling the aircraft at this flight speed, the exterior of the aircraft is aerodynamically heated. The exterior includes a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature. The first initial temperature is greater than the second initial temperature, and the temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference. A working fluid circulates through a fluid circuit. The fluid circuit is coupled to the first exterior panel and the second exterior panel. Heat is transferred from the first exterior panel to the working fluid, which reduces the first initial temperature of the first exterior panel to a first change temperature and heats the working fluid. The heated working fluid circulates from the first exterior panel and heats the second exterior panel to a second change temperature using the heated working fluid, the second change temperature being greater than the second initial temperature. The temperature difference between the first change temperature and the second change temperature defines an auxiliary temperature difference, which is less than the initial temperature difference.

[0005] The detailed description and drawings support and describe the present disclosure, but the scope of the claims of the present disclosure is limited only by the claims. Although some of the best modes and other configurations for implementing the claims have been described in detail, various alternative designs and configurations exist for practicing the disclosure defined in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic perspective view of an aircraft including an exterior having exterior panels and including the systems and methods described herein.

[0007] Figure 2 is a diagram of an example supercritical working fluid.

[0008] Figure 3 is a schematic diagram of a first configuration of the system.

[0009] Figure 4 is a schematic diagram of a second configuration of the system.

[0010] Figure 5 is a schematic diagram of a third configuration of the system.

[0011] Figure 6 is a schematic diagram of a fourth configuration of the system.

[0012] Figure 7 is a schematic cross-sectional perspective view of an exterior panel of a first configuration.

[0013] Figure 8 is a schematic cross-sectional perspective view of an exterior panel of a second configuration.

[0014] Fig. 9 is a schematic diagram of an external panel, sensors, and valves along a fluid circuit, wherein a controller communicates with the sensors and valves.

[0015] The present disclosure may be extended to modifications and alternative forms, wherein representative configurations are shown as examples in the accompanying drawings and are described in detail below. The inventive aspects of the present disclosure are not limited to the disclosed configurations. Rather, the present disclosure is intended to cover modifications, equivalents, combinations, and alternative forms that fall within the scope of the disclosure defined by the appended claims. DETAILED DESCRIPTION

[0016] Those of ordinary skill in the art will recognize that all directional references (e.g., above, below, upward, up, downward, down, top, bottom, left, right, vertical, horizontal, etc.) are used descriptively in the drawings to aid the reader's understanding and do not represent limitations on the scope of the disclosure as defined by the appended claims (e.g., to position, orientation, or use, etc.). In addition, terms such as "first," "second," "third," etc. may be used to describe separate components. Such terms may include the words specifically mentioned above, their derivatives, and words of similar meaning. In addition, the term "substantially" may refer to slight inaccuracies or slight differences in conditions, quantities, values, or dimensions, etc., some of which are within manufacturing differences or tolerances.

[0017] As used herein, elements or steps described in singular form and preceded by the word "one" or "a kind of" should be understood to not necessarily exclude a plurality of said elements or steps. In addition, any reference to "a configuration" is not intended to be interpreted as excluding the existence of other configurations that also contain the described features. In addition, unless explicitly stated to the contrary, a configuration that "includes" or "has" one or more elements with a specific property may include other elements that do not have that property. The phrase "at least one / kind" used herein should be interpreted as including a non-exclusive logical "or", i.e., A and / or B, etc. - according to the number of components.

[0018] Referring to the drawings, in which like numerals indicate like or corresponding parts throughout the several views, an aircraft 10 is generally shown in Figure 1 The aircraft 10 incorporates the system 12 and method 100 described herein. In general, the system 12 and method 100 described herein may be used to reduce temperature differences between different locations on the exterior 14 of the aircraft 10, which provides various benefits, improvements, advantages, etc., some of which are discussed below.

[0019] like Figure 1 As shown, the aircraft 10 includes an exterior 14 having a plurality of exterior panels 16. That is, the exterior 14 having the exterior panels 16 forms an exterior skin of the aircraft 10, which may include various types of panels, including but not limited to area panels, leading edge panels, duct panels (inlet duct 18 is shown in FIG. Figure 1 ), skin panels, engine combustion chamber liners, exhaust nozzles, etc. The external panels 16 are integrated with each other to form the external configuration of the aircraft 10. The external panels 16 can be arranged close to each other, that is, adjacent to each other, and a plurality of joints 20 are formed at locations where adjacent external panels 16 are joined together. The joints 20 are joined together at a mold line 22 to form a generally continuous external skin. The mold line 22 of the joint 20 may be thermally deformed due to temperature differences along the external panels 16. The system 12 and method 100 described herein can reduce or minimize thermal deformation along the mold line 22.

[0020] In general, when the aircraft 10 is propelled at a certain flight speed, the exterior 14 of the aircraft 10 is aerodynamically heated. When the aircraft 10 is traveling at the flight speed, different locations of the exterior 14 may be heated to different temperatures. For example, one of the exterior panels 16 may be heated to a different temperature than another exterior panel 16, and so on for each exterior panel 16 of the aircraft 10. As described herein, the system 12 and method 100 may redistribute heat from one or more exterior panels 16 to heat one or more other exterior panels 16, thereby reducing the temperature difference between the exterior panels 16, and by doing so, the aircraft 10 achieves a more uniform skin temperature, which may help reduce thermal deformation of the mold line 22.

[0021] With respect to the following discussion, the exterior 14 of the aircraft 10, and more specifically the exterior panels 16, may include a first exterior panel 16A and a second exterior panel 16B. The first exterior panel 16A and the second exterior panel 16B may be at different temperatures during flight, and therefore it may be desirable to reduce the temperature difference between these exterior panels 16A, 16B. For example, the first exterior panel 16A may include a windward skin panel 24 disposed along a bottom surface 26 of the aircraft 10, and the second exterior panel 16B may include a leeward skin panel 28 disposed along a top surface 30 of the aircraft 10. Due to the position of the windward skin panel 24 compared to the leeward skin panel 28, the windward skin panel 24 reaches a higher temperature than the leeward skin panel 28, and therefore it is desirable to reduce the temperature of the windward skin panel 24, and to use the heat from the windward skin panel 28 to increase the temperature of the leeward skin panel 28, which reduces the temperature difference between the windward skin panel 24 and the leeward skin surface 28.

[0022] Thus, disclosed herein is a system 12 for reducing temperature differentials across an aircraft 10 traveling at a flight speed of at least Mach 3. During operation of the aircraft 10 at a speed at or above Mach 3, including hypersonic flight (e.g., the aircraft 10 moves at a hypersonic speed at or above Mach 5), the exterior 14 of the aircraft 10 is aerodynamically heated. For example, the temperature of the exterior 14 of the aircraft 10 may exceed 1000 degrees Celsius (C). The following discussion will focus on the temperature differential between two locations, but it should be understood that the system 12 and method 100 may be applicable to any number of locations across the exterior 14 of the aircraft 10. Thus, for the following discussion, the exterior 14 of the aircraft 10 includes a first exterior panel 16A and a second exterior panel 16B.

[0023] In general, for Figure 3-6In all configurations of the system 12, the system 12 includes a fluid circuit 32 configured to contain a working fluid 33. The fluid circuit 32 is coupled to the external panels 16, and thus the aircraft 10 may include a fluid circuit 32 integrated along the external panels 16. For the purposes of the following example, the fluid circuit 32 is coupled to the first external panel 16A and the second external panel 16B so that heat is transferred from one or more external panels 16 to the working fluid 33. The heated working fluid 33 is then transferred through the fluid circuit 32 and used in various ways to heat one or more other external panels 16, as described below. Figure 3-6 Thus, for example, the heat transferred from the first outer panel 16A lowers the temperature of the first outer panel 16A, and the heated working fluid 33 is used to increase the temperature of the second outer panel 16B, thereby reducing the temperature difference between the first outer panel 16A and the second outer panel 16B.

[0024] The fluid circuit 32 may be coupled to the outer panel 16 at any suitable location. For example, the fluid circuit 32 may be disposed inside or integral with the outer panel 16, and as another example, the fluid circuit 32 may be disposed outside or adjacent to the outer panel 16. For example, Figure 7 A fluid circuit 32 is illustrated within one or more exterior panels 16, and Figure 8 The fluid circuit 32 is illustrated as being external to one or more of the exterior panels 16. Regardless of the location of the fluid circuit 32, the fluid circuit 32 is disposed within the interior of the aircraft 10 such that the fluid circuit 32 is not visible from the exterior of the aircraft 10 and therefore does not affect the aerodynamics of the aircraft 10.

[0025] For example, when the fluid circuit 32 is inside the outer panel 16, as shown in FIG. Figure 7 As shown in the illustration, the outer panel 16 may include a plurality of holes 34 defining a fluid circuit 32. The holes 34 are disposed between an outer surface 36 and an inner surface 38 of the outer panel 16. The holes 34 may be in any suitable configuration, and non-limiting examples may include a gyroscopic, cubic, diamond-shaped, triangular, random, circular, rectangular, wavy, or any other suitable configuration. Thus, in certain configurations, the holes 34 establish a porous structure through the outer panel 16, and the porous structure of the fluid circuit 32 may include a three-fold periodic minimum surface (gyroscopic), a grid structure, and the like.

[0026] refer to Figure 8, when the fluid circuit 32 is outside of the outer panel 16, the fluid circuit 32 is attached to the inner surface 38 of the outer panel 16. Thus, when the fluid circuit 32 is outside 14 of the outer panel 16, the fluid circuit 32 passes through the outer panel 16 in a serpentine pattern, a winding pattern, etc. relative to the inner surface 38 of the outer panel 16. The fluid circuit 32 may include one or more tubes 40 that are attached to the inner surface 38 of the outer panel 16. The tubes 40 may be any suitable configuration, and non-limiting examples may include circular, triangular, rectangular, or any other suitable configuration.

[0027] In certain configurations, the fluid circuit 32 is integrated into the windward skin panel 24 and the leeward skin panel 28. One or more mold lines 22 may join together the exterior panels 16, such as the windward skin panel 24 and the leeward skin panel 28. Generally, the fluid circuit 32 is integrated into the windward skin panel 24 and the leeward skin panel 28, adjacent to the mold line 22. By reducing the temperature difference between the windward skin panel 24 and the leeward skin panel 28, thermal deformation at the mold line 22 is reduced or minimized, which reduces structural loads along the fuselage of the aircraft 10. By reducing structural loads along the fuselage of the aircraft 10, the aerodynamics of the exterior 14 of the aircraft 10 may be improved, and fuel leakage may be minimized.

[0028] Depending on the type of working fluid 33 used, the working fluid 33 may be in a supercritical state. For example, because the aircraft 10 generates a certain amount of heat at high speeds, the working fluid 33 may be used in the fluid circuit 32, and the amount of heat absorbed by the working fluid 33 is such that the working fluid 33 remains in a supercritical state. When the temperature and pressure of the working fluid 33 are above the critical point, the working fluid 33 reaches a supercritical state (see Figure 2 ). Thus, heat from the exterior 14 of the aircraft 10 is transferred to the working fluid 33 in the fluid circuit 32, which maintains the working fluid 33 at a temperature and pressure above the critical point. Figure 2 The graph illustrates the critical point of the working fluid 33, where the temperature and pressure above the critical point will result in a supercritical state. The working fluid 33 can be any suitable substance, some of which reach a supercritical state and some of which do not reach a supercritical state. Non-limiting examples of the working fluid 33 can include supercritical carbon dioxide, supercritical helium (sHe), molten salt (one or more), sodium potassium alloy (NaK), cesium, lithium, etc. Therefore, an exemplary working fluid 33 that reaches a supercritical state can include carbon dioxide, helium, etc., and an exemplary working fluid 33 that does not reach a supercritical state can include molten salt (one or more), sodium potassium alloy (NaK), cesium, lithium, etc.

[0029] When the aircraft 10 is traveling at a flight speed of at least Mach 3, the first outer panel 16A is at a first initial temperature and the second outer panel 16B is at a second initial temperature. The first initial temperature is greater than the second initial temperature, and the temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference. The fluid circuit 32 is coupled to the first outer panel 16A and the second outer panel 16B so that heat is transferred from the first outer panel 16A to the working fluid 33 to reduce the first initial temperature of the first outer panel 16A to a first change temperature and heat the working fluid 33. The heated working fluid 33 circulates from the first outer panel 16A and is used to heat the second outer panel 16B to a second change temperature, which is greater than the second initial temperature. The temperature difference between the first change temperature and the second change temperature defines an auxiliary temperature difference, which is less than the initial temperature difference. The system 12 is activated to redistribute heat according to the initial temperature difference to obtain an auxiliary temperature difference, which results in the outer panels 16 being closer in temperature relative to each other than if the system 12 and method 100 described herein were not employed. By reducing the temperature differential between the exterior panels 16, this will help mitigate thermal deformation along the mold line 22, which helps reduce adverse structural loads caused by thermal deformation. In addition, by reducing the temperature differential between the exterior panels 16, thermal stresses in various components of the aircraft 10 can be reduced, and different types of materials with lower temperature characteristics can be used for various components of the aircraft 10.

[0030] Optionally, for any configuration herein, the system 12 may include a plurality of sensors 42 (see Figure 1 ), which is disposed along the exterior 14 of the aircraft 10. More specifically, one or more sensors 42 may be disposed along the exterior panel 16. The sensors 42 may be integrated into the exterior panel 16 or disposed along the interior surface 38 of the exterior panel 16. The sensors 42 are configured to provide information regarding the temperature of the exterior 14, and more specifically, provide information regarding the temperature of various locations of the exterior panel 16. Such temperature information may be used to monitor the temperature of the exterior 14 and / or determine where to redistribute heat across the aircraft 10. For example, the sensors 42 may be of any suitable configuration, and non-limiting examples may include temperature sensors that measure the actual temperature of the exterior 14 and / or strain sensors that measure thermal deformation of the exterior 14 to determine the temperature of the exterior 14.

[0031] For example, the sensors 42 may include a first sensor 42A coupled to the first outer panel 16A to measure the first initial temperature and the first changed temperature, and a second sensor 42B coupled to the second outer panel 16B to measure the second initial temperature and the second changed temperature. Thus, the first sensor 42A may be a temperature sensor or a strain sensor, or any other sensor suitable for providing information about the temperature of various locations of the outer panel 16. Although the present example includes two sensors 42, it should be understood that any suitable number of sensors 42 may be used along any suitable number of outer panels 16.

[0032] For illustrative purposes, some additional exterior panels 16 and sensors 42 are briefly discussed. Regarding this discussion, Fig. 9 A plurality of external panels 16 and a plurality of sensors 42 are schematically illustrated. Likewise, the discussion herein may apply to any suitable number of external panels 16 and sensors 42, and Fig. 9 For illustrative purposes. Thus, in certain configurations, the exterior 14 may include a third exterior panel 16C and a fourth exterior panel 16D, and the fluid circuit 32 may be coupled to the third exterior panel 16C and the fourth exterior panel 16D. Thus, the fluid circuit 32 may be coupled to the first exterior panel 16A, the second exterior panel 16B, the third exterior panel 16C, and / or the fourth exterior panel 16D. Optionally, the sensor 42 may further include a third sensor 42C and a fourth sensor 42D. Thus, in certain configurations, the third sensor 42C may be coupled to the third exterior panel 16C, and the fourth sensor 42D may be coupled to the fourth exterior panel 16D. The third sensor 42C may measure a third initial temperature and a third changed temperature of the third exterior panel 16C. The fourth sensor 42D may measure a fourth initial temperature and a fourth changed temperature of the fourth exterior panel 16D. Thus, the third sensor 42C can be a temperature sensor or a strain sensor, or any other sensor suitable for providing information about the temperature of various locations of the external panel 16, and similarly, the fourth sensor 42D can be a temperature sensor or a strain sensor, or any other sensor suitable for providing information about the temperature of various locations of the external panel 16.

[0033] The system 12 may also include a controller 44 ( Figure 1 ) that communicates with the sensors 42 to receive information regarding the temperature of the exterior 14. The controller 44 may utilize the information from the sensors 42 to monitor the temperature of the exterior 14, determine where to redistribute heat across the aircraft 10, and / or control other components of the system 12. It should be appreciated that the controller 44 may be used to perform other functions, some of which are discussed herein.

[0034] Returning to the sensors 42, for example, the controller 44 may communicate with the first sensor 42A and the second sensor 42B to receive information regarding the first initial temperature and the first changed temperature of the first exterior panel 16A and the second initial temperature and the second changed temperature of the second exterior panel 16B, and so on for the plurality of sensors 42 used. That is, the controller 44 may communicate with each of the sensors 42, and thus may communicate with the first sensor 42A, the second sensor 42B, the third sensor 42C, and / or the fourth sensor 42D, etc. The controller 44 may utilize the information regarding the temperature of the exterior 14 to determine where to redistribute heat across the exterior 14 of the aircraft 10, and thus achieve a more uniform skin temperature of the exterior 14.

[0035] In certain configurations, the system 12 may include a plurality of valves 46 coupled to the fluid circuit 32. The valves 46 may direct the heated working fluid 33 to a selected location of the exterior 14 of the aircraft 10 (e.g., the exterior panel 16). Thus, for example, one or more valves 46 may be opened or closed to direct the heated working fluid 33 to a desired location across the exterior panel 16. In general, the controller 44 communicates with the valves 46 such that the controller 44 is configured to control the opening and closing of the valves 46 based on information from one or more of the first temperature sensor 42A, the second temperature sensor 42B, the third temperature sensor 42C, and the fourth temperature sensor 42D to direct the heated working fluid 33 to one or more of the second exterior panel 16B, the third exterior panel 16C, and the fourth exterior panel 16D. In the above example, it is assumed that the first exterior panel 16A is the panel from which heat is acquired and redistributed to the second exterior panel 16B, the third exterior panel 16C, and / or the fourth exterior panel 16D, etc. It should be appreciated that more than one exterior panel 16 may be panels 16 , 24 , 28 from which heat is extracted and redistributed to other ones of the exterior panels 16 .

[0036] The valve 46 may be of any suitable configuration, and non-limiting examples of the valve 46 may include a passive valve 46 , an active valve 46 , a shape memory alloy (SMA) valve 46 , and the like.

[0037] Returning to the controller 44, instructions may be stored in the memory M of the controller 44 and automatically executed by the processor P of the controller 44 to provide the corresponding control function. Therefore, the controller 44 is configured to execute instructions from the memory M via the processor P. For example, the controller 44 may be a host or distributed system, for example, a computer such as a digital computer or a microcomputer, and as the memory M, may be a tangible, non-transitory computer-readable memory, such as a read-only memory (ROM) or flash memory. The controller 44 may also have a random access memory (RAM), an electrically erasable programmable read-only memory (EEPROM), a high-speed clock, analog-to-digital (A / D) and / or digital-to-analog (D / A) circuits, and any required input / output circuits and related devices, as well as any required signal conditioning and / or signal buffering circuits. Therefore, the controller 44 may include all software, firmware, hardware, memory M, algorithms, connections, sensors, etc. required to control, monitor, and determine, for example, valves 46, sensors 42, and other components coupled to the fluid circuit 32, as described below. It should be understood that the controller 44 may also include any device capable of analyzing data from the various sensors, comparing the data, and making the necessary decisions required to control and / or monitor the valves 46, sensors 42, and other components coupled to the fluid circuit 32, as described below. Optionally, more than one controller 44 may be used.

[0038] For example, the hardware of the controller 44 may include one or more processors P coupled to the current driver. The one or more processors P may include any electronic circuit and / or optical circuit capable of performing the functions described herein. For example, the (one or more) processors P may perform any of the functions described herein with respect to the controller 44. The (one or more) processors P may include one or more central processing units (CPUs), microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), programmable logic devices (PLDs), control circuits, etc. Some non-limiting examples of processors P may include CORE TM Processors, Advanced Reduced Instruction Set Computing (RISC) Machines Processor, etc.

[0039] Heat from the exterior 14 of the aircraft 10 may be redistributed in a number of different ways, and some examples are discussed below. Figure 3-6 Non-limiting examples of redistributing heat across the exterior 14 of the aircraft 10 are illustrated, each of which is discussed below.

[0040] Go to Figure 3-5, the system 12 may include a compressor 48 configured to compress the working fluid 33. Generally, the compressor 48 compresses the working fluid 33 to a boost pressure. Thus, depending on the type of working fluid 33, the compressor 48 compresses the working fluid 33 to a pressure above a critical point. The compressor 48 is disposed along the fluid circuit 32 in the aircraft 10 and may be located at different locations depending on the configuration.

[0041] The controller 44 receives feedback from the one or more sensors 42, and the controller 44 is programmed to activate the compressor 48 when the exterior 14 of the aircraft 10 exceeds a threshold temperature. Non-limiting example threshold temperatures for activating the compressor 48 may include about 500 degrees Celsius to about 1000 degrees Celsius. In other examples, the controller 44 determines whether to activate the compressor 48 using information about the flight speed of the aircraft 10, which indicates the temperature of the exterior 14 of the aircraft 10. When the aircraft 10 reaches the threshold flight speed, the controller 44 activates the compressor 48. Non-limiting example threshold flight speeds for activating the compressor 48 may include Mach 3, Mach 3.5, Mach 4, and hypersonic speeds.

[0042] refer to Figure 3 and Figure 5 In the configuration of the system 12, the system 12 may include a heat intake portion 50 configured to absorb heat from the first outer panel 16A and transfer the heat to the fluid circuit 32 to heat the working fluid 33. In general, the heat intake portion 50 may be a section of the fluid circuit 32 that is thermally coupled to the exterior 14, such as the outer panel 16. In addition, the system 12 may include a heat exhaust portion 51 configured to transfer heat from the fluid circuit 32 to the second outer panel 16B.

[0043] Continue to refer Figure 3 and Figure 5 , the system 12 may also include a heat engine 52, which is disposed downstream of the heat intake portion 50. The heat engine 52 is coupled to the compressor 48 and is configured to operate the compressor 48. For example, the heat engine 52 and the compressor 48 may be mechanically or electrically coupled to each other. In one example, the heat engine 52 includes a shaft 54 ​​coupled to the compressor 48. Therefore, a work output 56 from the heat engine 52 is transmitted to the compressor 48 via the shaft 54, or the work output 56 is transmitted to the compressor 48 via an electrical connection, and no matter how the work output 56 is coupled to the compressor 48, the work output causes the compressor 48 to operate. Therefore, for example, the heat engine 52 can generate torque as the work output 56, which is transmitted to the compressor 48 via the shaft 54. Using a supercritical working fluid 33 allows the compressor 48, the heat engine 52, and other components along the fluid circuit 32 to be smaller and lighter.

[0044] In general, the compressor 48 and the heat engine 52 divide the fluid circuit 32 into a low-pressure branch 58 and a high-pressure branch 60, wherein the low-pressure branch 58 is downstream of the heat engine 52 and opens to the inlet side 62 of the compressor 48, and the high-pressure branch 60 is upstream of the heat engine 54 and opens to the outlet side 64 of the compressor 48. Thus, the heat engine 52 can be operated to extract a work output 56 from the working fluid 33 by expanding the working fluid 33 to a reduced pressure.

[0045] Generally, a heat engine 52 is disposed along the fluid circuit 32 in the aircraft 10 and is disposed downstream of the heat intake 50. The heat engine 52 may be any configuration suitable for transmitting torque and / or extracting work output 56 from the pressurized working fluid 33, and non-limiting examples may include a turbine, a scroll expander, a thermoelectric converter, a thermionic converter, or any other suitable heat engine 52.

[0046] Continue to combine Figure 3 In a configuration of the system 12, the system 12 may include a generator 66 coupled to the heat engine 52. The generator 66 is configured to receive at least a portion of the work output 56 from the heat engine 52 to generate electricity. The electricity may be used to operate auxiliary loads, the engine generator 66, or any other type of load.

[0047] Again, continue combining Figure 3 In an embodiment of the present invention, the system 12 may optionally include a recuperator 68 disposed along the fluid loop 32 and coupled to the low-pressure branch 58 downstream of the turbine and to the high-pressure branch 60 downstream of the output side of the compressor 48. The recuperator 68 is configured to transfer heat from the low-pressure branch 58 of the fluid loop 32 to the high-pressure branch 60 of the fluid loop 32. Overall, the recuperator 68 may improve the thermal efficiency of the system 12. Thus, the recuperator 68 may operate as a heat exchanger. Transferring heat to the working fluid 33 via the recuperator 68 prior to further heating the working fluid 33 via the heat intake section 50 increases the temperature of the working fluid 33 entering the heat engine 52, which increases the amount of work output 56 that can be extracted from the working fluid 33.

[0048] Continue to combine Figure 3In a configuration of the present invention, the system 12 may include a precooler 70 disposed along the fluid loop 32 and coupled to the low pressure branch 58 upstream of the compressor 48 and downstream of the recuperator 68. The precooler 70 is configured to remove excess heat from the working fluid 33. Thus, for example, the precooler 70 can ensure that the temperature of the working fluid 33 does not exceed the operating temperature range of the compressor 48. Excess heat from the precooler 70 can be exhausted or discharged to the surrounding atmosphere or transferred to an auxiliary fluid in a heat dissipation loop 72 for use in another system of the aircraft 10. In certain configurations, the precooler 70 may include a precooler heat exchanger 74. Thus, the heat dissipation loop 72 transfers excess heat from the precooler 70 to a storage structure containing an auxiliary fluid or to a thermal energy storage device. The auxiliary fluid of the heat dissipation loop 72 can be any suitable fluid, and non-limiting examples can include fuels, such as hydrocarbon fuels (e.g., Jet-A, JP-8, JP-10, kerosene, RP2, etc.), cryogenic fuels (e.g., liquid hydrogen, liquid natural gas, etc.), etc.; water or other types of fluids in the aircraft 10 setting.

[0049] Reference again Figure 3 , the fluid circuit 32 forms a first circuit 32A and a second circuit 32B isolated from each other. The first circuit 32A and the second circuit 32B each contain a working fluid 33. The working fluid 33 of the first circuit 32A and the second circuit 32B may be any of the substances described above. In certain configurations, the working fluid 33 of the first circuit 32A is different from the working fluid 33 of the second circuit 32B. For example, the first circuit 32A may contain the working fluid 33 as a first substance, and the second circuit 32B may contain the working fluid 33 as a second substance. The second substance is different from the first substance. As another example, in certain configurations, the working fluid 33 of the first circuit 32A is in a supercritical state, and the working fluid 33 of the second circuit 32B is not in a supercritical state. In other configurations, the working fluid 33 is the same type of working fluid in both the first circuit 32A and the second circuit 32B. Thus, for example, the working fluid 33 may be in a supercritical state in both the first circuit 32A and the second circuit 32B. In Figure 3 In the configuration of , the first circuit 32A may be referred to as a high pressure circuit, and the second circuit 32B may be referred to as a low pressure circuit.

[0050] The system 12 may also include a heat exchanger 76 coupled to the first loop 32A and the second loop 32B (see Figure 3). In general, the heat exchanger 76 is disposed downstream of the turbine and upstream of the recuperator 68. The heat of the working fluid 33 from the first loop 32A is transferred to the second loop 32B via the heat exchanger 76 to heat the second external panel 16B. That is, the heat of the working fluid 33 from the first loop 32A is transferred to the working fluid 33 of the second loop 32B via the heat exchanger 76 to heat the working fluid 33 of the second loop 34B. Then, the second loop 32B delivers the heated working fluid 33 to the desired external panel 16 to heat or increase the temperature of the external panel 16.

[0051] In some configurations, more than one compressor 48 may be used. Thus, for example, referring again to Figure 3 , the compressor 48 is further defined as a first compressor 48A, and the first compressor 48A is coupled to the first circuit 32A. In this configuration, the system 12 may further include a second compressor 78 coupled to the second circuit 32B, and the second compressor 79 is configured to compress the working fluid 33 of the second circuit 32B. In general, the second compressor 78 compresses the working fluid 33 of the second circuit 32B to a boost pressure. Therefore, depending on the type of working fluid 33, the second compressor 78 compresses the working fluid 33 of the second circuit 32B, and if the working fluid 33 is a supercritical working fluid, the working fluid 33 of the second circuit 32B is compressed to a pressure above the critical point. The critical point is discussed above and will not be repeated.

[0052] Continue to refer Figure 3 , various external panels 16 (such as the first external panel 16A) and the heat intake portion 50, the heat engine 52 and the first compressor 48A are coupled to the first circuit 32A. The second circuit 32B is coupled to various external panels 16 (such as the second external panel 16B) and the second compressor 78. The second compressor 78 is arranged along the second fluid circuit 32 between the heat exchanger 76 and the external panel 16 to be heated.

[0053] Go to Figure 4, the fluid circuit 32 is a closed circuit between the various external panels 16. In this configuration, heat from the exterior 14 is transferred to the working fluid 33, which causes the external panel 16 to reduce the temperature of the external panel 16, and the heated working fluid 33 is then transferred to another external panel 16 via the compressor 48, which causes the other external panel 16 to increase the temperature of the other external panel 16. Thus, heat from the first external panel 16A can be transferred to the working fluid 33 via the heat intake portion 50, and the heated working fluid 33 can be transferred to the second external panel 16B via the heat output portion 51. Thus, for example, a closed circuit can be provided between the first external panel 16A, the second external panel 16B, and the compressor 48, so that the heated working fluid 33 circulates directly from the first external panel 16A to the second external panel 16B to heat the second external panel 16B to a second changed temperature greater than the second initial temperature.

[0054] Go to Figure 5 The system 12 may include a heat intake section 50, a heat engine 52, a compressor 48, a recuperator 68, a generator 66, and a precooler 70, as described above with respect to Figure 3 Some of these will be described in the configuration of Figure 5 , but see above for a detailed discussion of these features.

[0055] about Figure 5 , the heat engine 52 is disposed downstream of the heat intake section 50, and the heat engine 52 is operable to produce a work output 56, as described above. Thus, the compressor 48 and the generator 66 can be coupled to the heat engine 52 so that the compressor 48 and the generator 66 can use some of the work output 56. The recuperator 68 is disposed along the fluid circuit 32 and is coupled to the low-pressure branch 58 downstream of the turbine and to the high-pressure branch 60 downstream of the output side of the compressor 48. The precooler heat exchanger 74 of the precooler 70 is coupled to the low-pressure branch 58 upstream of the compressor 48 and downstream of the recuperator 68.

[0056] Continue to refer Figure 5, the system 12 may include a heater 80 coupled to one or more external panels 16. The heater 80 may be incorporated within the interior of one or more external panels 16, or disposed adjacent to the interior surface 38 of one or more external panels 16. For example, the heater 80 may be coupled to the second external panel 16B when it may be the external panel 16 to be heated to a higher temperature. The heater 80 and the generator 66 are electrically connected to each other so that the power from the generator 66 can operate the heater 80. The generator 66 is operably coupled to the heat engine 52 so that the work output 56 from the heat engine 52 is used to provide power to the heater 80 via the generator 66, which allows the heater 80 to heat the second external panel 16B. That is, the temperature of the first external panel 16A may be reduced by the heat transferred to the working fluid 33, and then the heated working fluid 33 from the first external panel 16A is transferred to the heat engine 52, which utilizes the heat to generate the work output 56 used via the generator 66, which ultimately increases the temperature of the second external panel 16B. The heater 80 may be of any suitable configuration, and non-limiting examples of the heater 80 may include heating elements such as blankets, plates, coils, belts, boxes, resistive heating, cylinders, ropes, etc. It should be understood that the generator 66 may be used to charge the battery, and the battery may be used to power the heater 80 or assist the generator 66 in powering the heater 80. In other configurations, the generator 66 may be replaced by a thermoelectric device used to power the heater 80.

[0057] Continue to combine Figure 5 , the controller 44 may communicate with the generator 66 and the heater 80. The controller 44 may utilize various information, including information from the sensor 42, to determine when to operate the heater 80.

[0058] Go to Figure 6 In the configuration of FIG. 8 , the fluid circuit 32 is configured as a heat pipe 82 having an evaporation side 84 disposed along the windward skin panel 24 and a condensation side 86 disposed along the leeward skin panel 28. The evaporation side 84 and the condensation side 86 are connected to each other via a plurality of intermediate tube connections 88. The evaporation side 84 is configured to heat the working fluid 33 to transfer heat away from the windward skin panel 24, and the heated working fluid 33 is transferred to the condensation side 86 through the intermediate tube connections 88 to transfer heat to the leeward skin panel 28.

[0059] In certain configurations, the heat pipe 82 is a thermal diode configuration, wherein the evaporation side 84 enhances heat transfer toward the condensation side 86, and the condensation side 86 inhibits heat transfer back to the evaporation side 84. More specifically, the intermediate pipe connection 88 transfers the working fluid 33 between the sides 84, 86, and may include components or features to cause heat transfer to the sides 84, 86. Thus, the windward skin panel 24 cools while the leeward skin panel 28 heats up to reduce the temperature difference between different locations of the exterior 14 of the aircraft 10. That is, the temperature of the windward skin panel 24 is reduced and the temperature of the leeward skin panel 28 is increased, which reduces the temperature difference between the locations. It should be understood that the valve 46 can be disposed in any suitable location, and non-limiting examples may include the fluid circuit 32 along the evaporation side 84, the fluid circuit 32 of the condensation side 86, and / or the intermediate pipe connection 88.

[0060] In general, the heat pipe 82 provides a passive means of diffusing and transferring the working fluid 33 to various locations on the exterior 14 of the aircraft. Various passive means may be used to diffuse and transfer the working fluid 33, and non-limiting examples may include gravity driven, such as thermosiphon, etc.; surface tension driven, such as heat pipes or vapor chambers, etc. The heat pipe 82 may include a tube 40 that is integral or one-piece with the exterior panel 16, or a tube 40 that is attached to the interior surface 38 of the exterior panel 16. The heat pipe 82 may be of any suitable configuration, and non-limiting examples may include an oscillating / pulsating heat pipe, a variable conductance heat pipe, etc.

[0061] The present disclosure also provides a method 100 for reducing a temperature differential across an exterior 14 of an aircraft 10. It should be understood that the order or sequence in which the method 100 is performed as described below is for example purposes, and that other orders or sequences are within the scope of the present teachings. It should also be understood that the method 100 may include other features not specifically discussed immediately below.

[0062] During flight of the aircraft 10, the exterior 14 may heat up due to aerodynamics. Once the aircraft 10 reaches a certain flight speed, it may be desirable to reduce the temperature differential across the exterior 14 of the aircraft 10. For example, it may be desirable to reduce the temperature differential across the exterior 14 of the aircraft 10 according to the method 100 described herein when the flight speed reaches at least Mach 3 or higher.

[0063] Thus, the method 100 includes propelling the aircraft 10 at a flight speed of at least Mach 3, and the exterior 14 of the aircraft 10 is aerodynamically heated by propelling the aircraft 10 at the flight speed. That is, by propelling the aircraft 10 at a flight speed of at least Mach 3, the exterior 14 of the aircraft 10 is aerodynamically heated.

[0064] As described above, the exterior 14 may include a first exterior panel 16A at a first initial temperature and a second exterior panel 16B at a second initial temperature. In addition, as described above, the first initial temperature is greater than the second initial temperature, and the temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference.

[0065] The working fluid 33 is circulated through the fluid circuit 32, and the working fluid 33 is used to transfer heat, as described herein. The fluid circuit 32 is coupled to the desired external panel 16, and can be coupled to the first external panel 16A and the second external panel 16B, for example. Heat from the first external panel 16A is transferred to the working fluid 33, which reduces the first initial temperature of the first external panel 16A to the first change temperature and heats the working fluid 33. The heated working fluid 33 circulates from the first external panel 16A, and the heated working fluid 33 is used to heat the second external panel 16B to a second change temperature greater than the second initial temperature. The temperature difference between the first change temperature and the second change temperature defines an auxiliary temperature difference, which is less than the initial temperature difference. By reducing the temperature difference between different locations of the exterior 14, different types of materials can be used for various components of the aircraft 10. In addition, by reducing the temperature difference between different locations of the exterior 14, the integrity along the mold line 22 can be improved, which reduces thermal stress and thermal deformation of the fuselage. In addition, by reducing the temperature difference between different locations of the exterior 14, the aircraft 10 can be constructed of materials with lower temperature characteristics.

[0066] Go to Figure 3 The configuration of the fluid circuit 32 forms a first circuit 32A and a second circuit 32B isolated from each other. The first circuit 32A and the second circuit 32B each contain a working fluid 33. The working fluid 33 of the first circuit 32A is compressed via the first compressor 48A. The heat engine 52 is operably coupled to the first compressor 48A to operate the first compressor 48A. Heat is absorbed from the first external panel 16A via the heat intake portion 50, and the heat is transferred to the first circuit 32A to heat the working fluid 33. That is, the working fluid 33 absorbs heat from the first external panel 16A via the heat intake portion 50. The first external panel 16A, the heat intake portion 50, the heat engine 52 and the first compressor 48A are coupled to the first circuit 32A. The working fluid 33 of the second circuit 32B is compressed via the second compressor 78. Heat is transferred from the working fluid 33 of the first circuit 32A to the working fluid 33 of the second circuit 32B via the heat exchanger 76 to heat the second external panel 16B. More specifically, the heated working fluid 33 of the first loop 32A transfers heat to the working fluid 33 of the second loop 32B via the heat exchanger 76. As described above, the controller 44 may be coupled to the first loop 32A. Figure 3The various components of the configuration communicate, such as the optional sensor 42, the optional valve 46, the generator 66, the first compressor 48A, the second compressor 78, etc.

[0067] Go to Figure 4 In the configuration, the fluid circuit 32 is a closed loop between the first outer panel 16A, the second outer panel 16B and the compressor 48. In this configuration, circulating the heated working fluid 33 can further include circulating the heated working fluid 33 directly from the first outer panel 16A to the second outer panel 16B to heat the second outer panel 16B to a second changed temperature greater than the second initial temperature. As described above, the controller 44 can be connected to Figure 4 The various components of the configuration communicate, such as optional sensor 42, optional valve 46, compressor 48, etc.

[0068] refer to Figure 5 configuration, the working fluid 33 is compressed via the compressor 48. Heat is absorbed from the first outer panel 16A via the heat intake portion 50, and the heat is transferred to the fluid circuit 32 to heat the working fluid 33. The heat engine 52 is operably coupled to the generator 66, so that the work output 56 from the heat engine 52 is used to provide electricity via the generator 66. In addition, the heat engine 52 is coupled to the compressor 48 to operate the compressor 48. The compressor 48 compresses the working fluid 33 to increase the pressure of the working fluid 33. The electricity from the generator 66 can be used to operate the heater 80 via the heater 80. The heater 80, which is coupled to the second outer panel 16B, is operated via the electricity from the generator 66 to heat the second outer panel 16B. That is, the operation of the heater 80 can increase the temperature of the second outer panel 16B. As described above, the controller 44 can be used with Figure 5 The various components of the configuration communicate, such as the optional sensor 42, the optional valve 46, the generator 66, the compressor 48, the heater, etc.

[0069] Go to Figure 6 In the configuration described above, the first exterior panel 16A may include a windward skin panel 24 disposed along a bottom surface 26 of the aircraft 10, and the second exterior panel 16B may include a leeward skin panel 28 disposed along a top surface 30 of the aircraft 10. The fluid circuit 32 is configured as a heat pipe 82, which may include an evaporation side 84 disposed along the windward skin panel 24 and a condensation side 86 disposed along the leeward skin panel 28. The evaporation side 84 and the condensation side 86 are connected to each other via a tube connection. In this configuration, circulating the heated working fluid 33 may further include passively circulating the heated working fluid 33 from the evaporation side 84 away from the windward skin panel 24 to the condensation side 86 through the intermediate tube connection 88 to transfer heat to the leeward skin panel 28. As described above, the controller 44 may be coupled to the heat pipe 82. Figure 6The various components of the configuration communicate, such as optional sensor 42, optional valve 46, etc.

[0070] Although the best mode and other configurations for implementing the present disclosure have been described in detail, those skilled in the art who are familiar with the present disclosure will recognize various alternative designs and configurations for practicing the present disclosure within the scope of the appended claims. In addition, the features of the configurations shown in the drawings or the various configurations mentioned in this specification are not necessarily understood as configurations that are independent of each other. On the contrary, the features described in one of the examples of a configuration can be combined with one or more other desired features in other configurations to produce other configurations that are not described in words or with reference to the drawings. Therefore, such other configurations fall within the scope of the appended claims.

[0071] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is indeed capable of performing the specified function without any changes, rather than just being likely to perform the specified function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is selected, created, implemented, utilized, programmed, and / or designed specifically to perform the specified function. As used herein, "configured to" represents an existing feature of a system, device, structure, article, element, component, or hardware that enables the system, device, structure, article, element, component, or hardware to perform the specified function without further modification. For the purposes of this disclosure, a system, device, structure, article, element, component, or hardware that is described as "configured to" perform a particular function may be additionally or alternatively described as "suitable for" and / or "operable to" perform that function.

[0072] The examples of the embodiments described herein are intended to provide a general understanding of the structures of the various embodiments. These examples are not intended to be a complete description of all elements and features of the equipment and systems utilizing the structures or methods described herein. Many other embodiments may be apparent to those skilled in the art after reading this disclosure. Other embodiments may be utilized and derived based on the disclosure so that structural and logical replacements and changes may be made without departing from the scope of the disclosure. Therefore, the disclosure and the accompanying drawings will be considered to be exemplary and non-restrictive.

[0073] The following clauses provide some example configurations of the system 12 , aircraft 10 , and method 100 disclosed herein.

[0074] Item 1: A system for reducing a temperature differential across an aircraft traveling at a flight speed of at least Mach 3, the system comprising: an exterior of the aircraft, comprising a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature, wherein the first initial temperature is greater than the second initial temperature, and a temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference; a fluid circuit configured to contain a working fluid; wherein the fluid circuit is coupled to the first exterior panel and the second exterior panel such that heat is transferred from the first exterior panel to the working fluid to reduce the first initial temperature of the first exterior panel to a first altered temperature and to heat the working fluid; and wherein the heated working fluid is circulated from the first exterior panel and used to heat the second exterior panel to a second altered temperature greater than the second initial temperature, wherein the temperature difference between the first altered temperature and the second altered temperature defines an auxiliary temperature difference that is less than the initial temperature difference.

[0075] Clause 2: The system of clause 1, further comprising a plurality of sensors, the sensors comprising a first sensor coupled to the first exterior panel to measure a first initial temperature and a first changed temperature, and a second sensor coupled to the second exterior panel to measure a second initial temperature and a second changed temperature.

[0076] Clause 3: The system of any of the preceding clauses, further comprising a controller in communication with the first sensor and the second sensor to receive information regarding the first initial temperature and the first changed temperature of the first exterior panel and the second initial temperature and the second changed temperature of the second exterior panel.

[0077] Clause 4: A system as described in any of the preceding clauses: wherein the exterior includes a third exterior panel and a fourth exterior panel, and the fluid circuit is coupled to the third exterior panel and the fourth exterior panel; wherein the sensor also includes a third sensor coupled to the third exterior panel and a fourth sensor coupled to the fourth exterior panel; and further comprising a plurality of valves coupled to the fluid circuit, and a controller communicates with the valves such that the controller is configured to control the opening and closing of the valves based on information from one or more of the first sensor, the second sensor, the third sensor, and the fourth sensor to direct the heated working fluid to one or more of the second exterior panel, the third exterior panel, and the fourth exterior panel.

[0078] Clause 5: The system of any of the preceding clauses, further comprising a compressor configured to compress the working fluid.

[0079] Clause 6: The system of any of the preceding clauses, further comprising: a heat intake portion configured to absorb heat from the first external panel and transfer the heat to the fluid circuit to heat the working fluid; and a heat engine coupled to the compressor and configured to operate the compressor, wherein the heat engine is disposed downstream of the heat intake portion.

[0080] Clause 7: A system as described in any of the preceding clauses, wherein the fluid circuit forms a first circuit and a second circuit isolated from each other, and the first circuit contains a working fluid as a first substance, and the second circuit contains a working fluid as a second substance, the second substance being different from the first substance; wherein a first external panel, a heat intake portion, a heat engine and a compressor are coupled to the first circuit; wherein the second circuit is coupled to the second external panel; and further comprising a heat exchanger, the heat exchanger being coupled to the first circuit and the second circuit, and heat from the working fluid of the first circuit is transferred to the second circuit via the heat exchanger to heat the second external panel.

[0081] Clause 8: The system of any of the preceding clauses, wherein the compressor is further defined as a first compressor; and further comprising a second compressor coupled to the second circuit and configured to compress the working fluid.

[0082] Clause 9: The system of one of clauses 1-6, further comprising: a heater coupled to the second external panel; and a generator operably coupled to the heat engine such that work output from the heat engine is used via the generator to provide power to the heater, allowing the heater to heat the second external panel.

[0083] Clause 10: The system of one of clauses 1-5, wherein the fluid circuit is a closed circuit between the first external panel, the second external panel, and the compressor such that the heated working fluid circulates directly from the first external panel to the second external panel to heat the second external panel to a second changed temperature greater than the second initial temperature.

[0084] Clause 11: The system of one of clauses 1-4, wherein the first exterior panel comprises a windward skin panel disposed along a bottom surface of the aircraft, and the second exterior panel comprises a leeward skin panel disposed along a top surface of the aircraft.

[0085] Clause 12: The system of one of clauses 1-4 or 11, wherein the fluid circuit is integrated in the windward skin panel and the leeward skin panel.

[0086] Clause 13: The system of one of clauses 1-4, 11, or 12, wherein the exterior includes a plurality of mold lines joining the windward skin panels and the leeward skin panels, and wherein the fluid circuit is integrated into the windward skin panels and the leeward skin panels adjacent the mold lines.

[0087] Clause 14: A system as described in one of clauses 1-4 or 11-13, wherein: the fluid circuit is configured as a heat pipe, the heat pipe including an evaporation side arranged along the windward skin panel and a condensation side arranged along the leeward skin panel; the evaporation side and the condensation side are connected to each other via a plurality of intermediate pipe connections; and the evaporation side is configured to heat a working fluid to transfer heat away from the windward skin panel, and the heated working fluid is transferred to the condensation side through the intermediate pipe connections to transfer heat to the leeward skin panel.

[0088] Clause 15: The system of one of clauses 1-4 or 11-14, wherein the heat pipe is a thermal diode configuration, wherein the evaporation side enhances heat transfer toward the condensation side, and the condensation side inhibits heat transfer back toward the evaporation side.

[0089] Item 16: A method for reducing a temperature differential across an exterior of an aircraft, the method comprising: propelling the aircraft at a flight speed of at least Mach 3, wherein the exterior of the aircraft is aerodynamically heated by propelling the aircraft at the flight speed, and wherein the exterior includes a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature, wherein the first initial temperature is greater than the second initial temperature, and a temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference; circulating a working fluid through a fluid circuit, wherein the fluid circuit is coupled to the first exterior panel and the second exterior panel; transferring heat from the first exterior panel to the working fluid, which reduces the first initial temperature of the first exterior panel to a first changed temperature and heats the working fluid; and circulating the heated working fluid from the first exterior panel and heating the second exterior panel to a second changed temperature greater than the second initial temperature using the heated working fluid, wherein the temperature difference between the first changed temperature and the second changed temperature defines an auxiliary temperature difference, the auxiliary temperature difference being less than the initial temperature difference.

[0090] Clause 17: The method described in Clause 16: wherein the fluid circuit forms a first circuit and a second circuit isolated from each other, and the first circuit and the second circuit each contain a working fluid; further comprising compressing the working fluid of the first circuit via a first compressor; further comprising operably coupling a heat engine to the first compressor to run the first compressor; further comprising absorbing heat from a first external panel via a heat intake portion and transferring the heat to the first circuit to heat the working fluid, wherein the first external panel, the heat intake portion, the heat engine and the first compressor are coupled to the first circuit; further comprising compressing the working fluid of the second circuit via a second compressor; and further comprising transferring heat from the working fluid of the first circuit to the working fluid of the second circuit via a heat exchanger to heat the second external panel.

[0091] Clause 18: The method of clause 16, wherein the fluid circuit is a closed circuit between the first external panel, the second external panel and the compressor; wherein circulating the heated working fluid also includes circulating the heated working fluid directly from the first external panel to the second external panel to heat the second external panel to a second changed temperature greater than the second initial temperature.

[0092] Clause 19: The method described in Clause 16 also includes: compressing a working fluid via a compressor; absorbing heat from a first external panel via a heat intake portion and transferring the heat to a fluid circuit to heat the working fluid; operably coupling the heat engine to a generator so that work output from the heat engine is used to provide electricity via the generator, and wherein the heat engine is coupled to the compressor to operate the compressor; and operating a heater coupled to a second external panel via electricity from the generator to heat the second external panel.

[0093] Clause 20: The method described in Clause 16, wherein: the first external panel includes a windward skin panel arranged along the bottom surface of the aircraft, and the second external panel includes a leeward skin panel arranged along the top surface of the aircraft; the fluid circuit is configured as a heat pipe, and the heat pipe includes an evaporation side arranged along the windward skin panel and a condensation side arranged along the leeward skin panel; the evaporation side and the condensation side are connected to each other via a plurality of intermediate pipe connections; and circulating the heated working fluid also includes passively circulating the heated working fluid from the evaporation side away from the windward skin panel to the condensation side through the intermediate pipe connections to transfer heat to the leeward skin panel.

Claims

1. A system (12) for reducing temperature differentials across an aircraft (10) travelling at a flight speed of at least Mach 3, the system (12) comprising: an exterior (14) of the aircraft (10) comprising a first exterior panel (16A) at a first initial temperature and a second exterior panel (16B) at a second initial temperature, wherein the first initial temperature is greater than the second initial temperature and a temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference; a fluid circuit (32) configured to contain a working fluid (33); wherein the fluid circuit (32) is coupled to the first outer panel (16A) and the second outer panel (16B) such that heat is transferred from the first outer panel (16A) to the working fluid (33) to reduce the first initial temperature of the first outer panel (16A) to a first changed temperature and heat the working fluid (33); and wherein the heated working fluid (33) circulates from the first outer panel (16A) and is used to heat the second outer panel (16B) to a second changed temperature, the second changed temperature being greater than the second initial temperature, wherein the temperature difference between the first changed temperature and the second changed temperature defines an auxiliary temperature difference, the auxiliary temperature difference being less than the initial temperature difference.

2. The system (12) according to claim 1 further includes a plurality of sensors (42), wherein the plurality of sensors (42) include a first sensor (42A) and a second sensor (42B), wherein the first sensor (42A) is coupled to the first external panel (16A) to measure the first initial temperature and the first changed temperature, and the second sensor (42B) is coupled to the second external panel (16B) to measure the second initial temperature and the second changed temperature.

3. The system (12) according to claim 2 further includes a controller (44), which communicates with the first sensor (42A) and the second sensor (42B) to receive information about the first initial temperature and the first changed temperature of the first external panel (16A) and the second initial temperature and the second changed temperature of the second external panel (16B).

4. The system (12) according to claim 3: wherein the exterior (14) includes a third exterior panel (16C) and a fourth exterior panel (16D), and the fluid circuit (32) is coupled to the third exterior panel (16C) and the fourth exterior panel (16D); wherein the sensor (42) further comprises a third sensor (42C) coupled to the third outer panel (16C) and a fourth sensor (42D) coupled to the fourth outer panel (16D); and It also includes a plurality of valves (46) coupled to the fluid circuit (32), and the controller (44) communicates with the valves (46), so that the controller (44) is configured to control the opening and closing of the valves (46) based on information from one or more of the first sensor (42A), the second sensor (42B), the third sensor (42C) and the fourth sensor (42D) to guide the heated working fluid (33) to one or more of the second external panel (16B), the third external panel (16C) and the fourth external panel (16D).

5. The system (12) of claim 1, further comprising a compressor (48) configured to compress the working fluid (33).

6. The system (12) of claim 5, further comprising: a heat intake portion (50) configured to absorb heat from the first outer panel (16A) and transfer the heat to the fluid circuit (32) to heat the working fluid (33); and A heat engine (52) is coupled to the compressor (48) and configured to operate the compressor (48), and wherein the heat engine (52) is disposed downstream of the heat intake (50).

7. The system (12) according to claim 6: wherein the fluid circuit (32) forms a first circuit (32A) and a second circuit (32B) isolated from each other, and the first circuit (32A) contains the working fluid (33) as a first substance, and the second circuit (32B) contains the working fluid (33) as a second substance, the second substance being different from the first substance; wherein the first exterior panel (16A), the heat intake portion (50), the heat engine (52) and the compressor (48) are coupled to the first circuit (32A); wherein the second loop (32B) is coupled to the second outer panel (16B); and A heat exchanger (76) is also included which is coupled to the first circuit (32A) and the second circuit (32B), and heat of the working fluid (33) from the first circuit (32A) is transferred to the second circuit (32B) via the heat exchanger (76) to heat the second outer panel (16B).

8. The system (12) according to claim 7: wherein the compressor (48) is further defined as a first compressor (48A); and Also included is a second compressor (78) coupled to the second circuit (32B) and configured to compress the working fluid (33).

9. The system (12) of claim 6, further comprising: a heater (80), the heater (80) coupled to the second outer panel (16B); as well as A generator (66) operably coupled to the heat engine (52) such that work output (56) from the heat engine (52) is used via the generator (66) to provide power to the heater (80), which allows the heater (80) to heat the second exterior panel (16B).

10. The system (12) of claim 5, wherein the fluid circuit (32) is a closed circuit between the first external panel (16A), the second external panel (16B), and the compressor (48), such that the heated working fluid (33) circulates directly from the first external panel (16A) to the second external panel (16B) to heat the second external panel (16B) to the second changed temperature greater than the second initial temperature.

11. The system (12) of claim 1, wherein the first exterior panel (16A) comprises a windward skin panel (24) disposed along a bottom surface (26) of the aircraft (10), and the second exterior panel (16B) comprises a leeward skin panel (28) disposed along a top surface (30) of the aircraft (10).

12. The system (12) of claim 11, wherein the fluid circuit (32) is integrated into the windward skin panel (24) and the leeward skin panel (28).

13. The system (12) of claim 12, wherein the exterior (14) includes a plurality of mold lines (22) joining the windward skin panel (24) and the leeward skin panel (28), and wherein the fluid circuit (32) is integrated into the windward skin panel (24) and the leeward skin panel (28) adjacent the mold lines (22).

14. The system (12) of claim 11, wherein: The fluid circuit (32) is configured as a heat pipe (82), the heat pipe (82) including an evaporation side (84) disposed along the windward skin panel (24) and a condensation side (86) disposed along the leeward skin panel (28); The evaporation side (84) and the condensation side (86) are connected to each other via a plurality of intermediate pipe connections (88); and The evaporation side (84) is configured to heat the working fluid (33) to transfer heat away from the windward skin panel (24), and the heated working fluid (33) is transferred to the condensation side (86) through the intermediate pipe connection (88) to transfer heat to the leeward skin panel (28).

15. The system (12) of claim 14, wherein the heat pipe (82) is a thermal diode configuration, wherein the evaporation side (84) enhances heat transfer toward the condensation side (86) and the condensation side (86) inhibits heat transfer back toward the evaporation side (84).

16. A method (100) for reducing a temperature difference on an exterior (14) of an aircraft (10), the method (100) comprising: Propelling the aircraft (10) at a flight speed of at least Mach 3, wherein the exterior (14) of the aircraft (10) is aerodynamically heated by propelling the aircraft (10) at the flight speed, and wherein the exterior (14) includes a first exterior panel (16A) at a first initial temperature and a second exterior panel (16B) at a second secondary initial temperature, wherein the first initial temperature is greater than the second initial temperature, and a temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference; circulate a working fluid (33) through a fluid circuit (32), wherein the fluid circuit (32) is coupled to the first outer panel (16A) and the second outer panel (16B); transferring heat from the first outer panel (16A) to the working fluid (33), which reduces the first initial temperature of the first outer panel (16A) to a first changed temperature and heats the working fluid (33); and The heated working fluid (33) is circulated from the first outer panel (16A), and the second outer panel (16B) is heated to a second changed temperature greater than the second initial temperature using the heated working fluid (33), wherein the temperature difference between the first changed temperature and the second changed temperature defines an auxiliary temperature difference, which is less than the initial temperature difference.

17. The method (100) according to claim 16: wherein the fluid circuit (32) forms a first circuit (32A) and a second circuit (32B) which are isolated from each other, and the first circuit (32A) and the second circuit (32B) each contain the working fluid (33); Also includes compressing the working fluid (33) of the first circuit (32A) via a first compressor (48A); Also included is operatively coupling a heat engine (52) to the first compressor (48A) to operate the first compressor (48A); Also includes absorbing heat from the first external panel (16A) via a heat intake portion (50) and transferring the heat to the first circuit (32A) to heat the working fluid (33), wherein the first external panel (16A), the heat intake portion (50), the heat engine (52) and the first compressor (48A) are coupled to the first circuit (32A); Also includes compressing the working fluid (33) of the second circuit (32B) via a second compressor (78); and Also included is transferring heat from the working fluid (33) of the first loop (32A) to the working fluid (33) of the second loop (32B) via a heat exchanger (76) to heat the second outer panel (16B).

18. The method (100) of claim 16, wherein the fluid circuit (32) is a closed circuit between the first external panel (16A), the second external panel (16B) and a compressor (48); wherein circulating the heated working fluid (33) further comprises circulating the heated working fluid (33) directly from the first external panel (16A) to the second external panel (16B) to heat the second external panel (16B) to the second changed temperature greater than the second initial temperature.

19. The method (100) of claim 16, further comprising: compressing the working fluid (33) via a compressor (48); absorbing heat from the first outer panel (16A) via a heat intake portion (50) and transferring the heat to the fluid circuit (32) to heat the working fluid (33); operatively coupling a heat engine (52) to a generator (66) such that work output (56) from the heat engine (51) is used to provide electrical power via the generator (66), and wherein the heat engine (53) is coupled to the compressor (48) to operate the compressor (48); and A heater (80) coupled to the second outer panel (16B) is operated by power from the generator (66) to heat the second outer panel (16B).

20. The method (100) of claim 16, wherein: The first exterior panel (16A) includes a windward skin panel (24) disposed along a bottom surface (26) of the aircraft (10), and the second exterior panel (16B) includes a leeward skin panel (28) disposed along a top surface (30) of the aircraft (10); The fluid circuit (32) is configured as a heat pipe (82), the heat pipe (82) including an evaporation side (84) disposed along the windward skin panel (24) and a condensation side (86) disposed along the leeward skin panel (28); The evaporation side (84) and the condensation side (86) are connected to each other via a plurality of intermediate pipe connections (88); and Circulating the heated working fluid (33) also includes passively circulating the heated working fluid (33) from the evaporation side (84) away from the windward skin panel (24) to the condensation side (86) through the intermediate tube connection (88) to transfer heat to the leeward skin panel (28).

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