Method and system for reducing temperature differential across flight vehicle

Abstract

To provide a method and a system for reducing a temperature differential across a flight vehicle.SOLUTION: An exterior 14 of a flight vehicle 10 includes a first exterior panel being at a first initial temperature, and a second exterior panel being at a second initial temperature, the first and second initial temperatures defining an initial temperature differential. A fluid loop 32 is coupled to the first exterior panel and the second exterior panel, so that heat is transferred from the first exterior panel to working fluid to decrease the first initial temperature of the first exterior panel to a first altered temperature and to heat the working fluid. The heated working fluid is circulated from the first exterior panel and used to heat the second exterior panel to a second altered temperature higher than the second initial temperature.SELECTED DRAWING: Figure 6

Description

[Background technology]

[0001]

[0001] A flight vehicle flying through the atmosphere at a flight speed of at least Mach 3 may experience aerodynamic heating of the exterior surface of the flight vehicle. The aerodynamic heating may result in the exterior surface of the flight vehicle reaching high temperatures, and these types of flight vehicles may be designed using materials suitable for the high temperatures resulting from flight speeds of at least Mach 3. However, at flight speeds of at least Mach 3, different temperatures are reached at different points on the exterior surface of the flight vehicle, resulting in thermal distortion of the airframe of the flight vehicle and / or increased demand for fuel heat sinks to thermally balance the flight vehicle. Summary of the Invention

[0002]

[0002] It is therefore desirable to develop methods and systems for reducing temperature differences between various locations on the exterior of a flight vehicle.

[0003]

[0003] The present disclosure provides a system for reducing a temperature difference across a flight vehicle moving at a flight speed of at least Mach 3. The system includes an exterior of the flight vehicle. The exterior of the flight vehicle 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 higher than the second initial temperature. A temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference. The system also includes a fluid loop configured to contain a working fluid. The fluid loop is coupled to the first exterior panel and the second exterior panel. Heat is thereby transferred from the first exterior panel to the working fluid to reduce the first initial temperature of the first exterior panel to a first modified temperature and to heat the working fluid. The heated working fluid is circulated from the first exterior panel and used to heat the second exterior panel to a second modified temperature higher than the second initial temperature. The temperature difference between the first altered temperature and the second altered temperature defines a second temperature difference that is less than the initial temperature difference.

[0004]

[0004] The present disclosure also provides a method for reducing a temperature difference across an exterior of a flight vehicle. The flight vehicle advances at a flight speed of at least Mach 3. The exterior of the flight vehicle is aerodynamically heated by the flight vehicle advancing at the flight speed. 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 higher 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 working fluid is circulated through a fluid loop. The fluid loop is coupled to the first exterior panel and the second exterior panel. Heat is transferred from the first exterior panel to the working fluid, thereby reducing the first initial temperature of the first exterior panel to a first modified temperature and heating the working fluid. The heated working fluid is circulated from the first exterior panel and the heated working fluid is used to heat the second exterior panel to a second modified temperature higher than the second initial temperature. The temperature difference between the first altered temperature and the second altered temperature defines a second temperature difference that is less than the initial temperature difference.

[0005]

[0005] The detailed description and drawings or figures support and explain the present disclosure, but the scope of the present disclosure is defined only by the claims. Although some of the best modes and other configurations for carrying out the claims have been described in detail, there are various alternative designs and configurations for carrying out the present disclosure as defined within the scope of the appended claims. [Brief description of the drawings]

[0006] [Figure 1]

[0006] FIG. 1 is a schematic perspective view of a flight vehicle including an exterior having exterior panels, the flight vehicle incorporating the systems and methods described herein. [Diagram 2]

[0007] 1 is a graph of an exemplary supercritical working fluid. [Diagram 3]

[0008] FIG. 2 is a schematic diagram of a first configuration of the system. [Figure 4]

[0009] FIG. 2 is a schematic diagram of a second configuration of the system. [Diagram 5]

[0010] FIG. 13 is a schematic diagram of a third configuration of the system. [Figure 6]

[0011] FIG. 11 is a schematic diagram of a fourth configuration of the system. [Figure 7]

[0012] FIG. 2 is a schematic cross-sectional perspective view of an exterior panel of a first configuration. [Figure 8]

[0013] FIG. 11 is a schematic cross-sectional perspective view of an exterior panel of a second configuration. [Figure 9]

[0014] 1 is a schematic diagram of skin panels, sensors, and valves along a fluid loop, with a controller in communication with the sensors and valves. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007]

[0015] The present disclosure may extend to modifications and alternatives using the representative configurations shown as examples in the drawings and described in detail below. The inventive aspects of the present disclosure are not limited to the configurations of the present disclosure. Rather, the present disclosure is intended to cover modifications, equivalents, combinations, and alternatives that fall within the scope of the present disclosure as defined by the appended claims.

[0008]

[0016] Those skilled in the art will recognize that all directional references (e.g., up, down, upper, lower, lower, upper, lower, left, right, vertical, horizontal, etc.) are used descriptively with respect to the figures to aid in the reader's understanding, and do not represent limitations (e.g., position, orientation, or use, etc.) on the scope of the present disclosure as defined by the appended claims. Furthermore, terms such as "first", "second", "third", etc. may be used to describe separate components. Such terms may include the terms specifically mentioned above, their derivatives, and similar terms. Furthermore, the term "substantially" may refer to slight inaccuracies or slight variations in conditions, amounts, values, or dimensions, etc., some of which are within manufacturing variations or tolerances.

[0009]

[0017] As used herein, a singular element or step following the word "a" or "an" should be understood not to necessarily exclude a plurality of such elements or steps. Moreover, any reference to "a configuration" is not intended to be interpreted as excluding the existence of additional configurations that also incorporate the recited features. Furthermore, unless expressly stated to the contrary, a multiple configuration "comprising" or "having" one or more elements having a particular property may include additional elements that do not have that property. The phrase "at least one" as used herein should be interpreted as including a non-exclusive logical "or", i.e., A and / or B, etc., depending on the number of components.

[0010]

[0018] Referring to the drawings, in which like numerals indicate like or corresponding parts throughout the several views, a flight vehicle 10 is generally shown in FIG. The flight vehicle 10 incorporates a system 12 and method 100 as described herein. Generally, the system 12 and method 100 described herein may be used to reduce temperature differences between various locations on an exterior 14 of the flight vehicle 10. This provides various benefits, improvements and advantages, some of which are described below.

[0011]

[0019] As shown in FIG. 1, the flight vehicle 10 includes an exterior 14 having a plurality of exterior panels 16. That is, the exterior 14 having the exterior panels 16 forms the exterior skin of the flight vehicle 10. The exterior skin may include various types of panels, including, but not limited to, acre panels, leading edge panels, duct panels (inlet duct 18 shown in FIG. 1), skin panels, engine combustor liners, exhaust nozzles, and the like. The exterior panels 16 are integrated with one another to form the exterior configuration of the flight vehicle 10. The exterior panels 16 may be positioned proximate, or adjacent to, one another, and a plurality of joints 20 are formed where adjacent ones of the exterior panels 16 are joined to one another. The joints 20 are joined together at mold lines 22 to form a generally continuous exterior skin. The mold lines 22 of the joints 20 may be subject to thermal distortion due to temperature differences along the exterior panels 16. The system 12 and method 100 described herein may reduce or minimize the thermal distortion along the mold lines 22.

[0012]

[0020] Generally, the exterior 14 of the flight vehicle 10 is aerodynamically heated as the flight vehicle 10 moves forward at flight speed. As the flight vehicle 10 moves at 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 temperature that is different from the temperature of another one of the exterior panels 16, as is the case for each of the exterior panels 16 of the flight vehicle 10. As described herein, the system 12 and method 100 may redistribute heat from one or more of the exterior panels 16 to heat one or more other of the exterior panels 16 to reduce the temperature difference between the exterior panels 16. By doing so, the flight vehicle 10 may achieve a more uniform skin temperature, which may help alleviate thermal distortion of the mold line 22.

[0013]

[0021] In the following description, the exterior 14 of the flight vehicle 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. 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 lower surface 26 of the flight vehicle 10. The second exterior panel 16B may include a leeward skin panel 28 disposed along an upper surface 30 of the flight vehicle 10. Due to the location 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. Therefore, it may be desirable to reduce the temperature of the windward skin panel 24 and use heat from the windward skin panel 24 to increase the leeward skin panel 28 temperature. This reduces the temperature difference between the windward skin panel 24 and the leeward skin panel 28.

[0014]

[0022] Thus, disclosed herein is a system 12 for reducing temperature differentials throughout a flight vehicle 10 moving at a flight speed of at least Mach 3. During operation of the flight vehicle 10 at speeds above Mach 3, including hypersonic flight (e.g., the flight vehicle 10 moves at a hypersonic speed of Mach 5 or greater), the exterior 14 of the flight vehicle 10 is aerodynamically heated. For example, the temperature of the exterior 14 of the flight vehicle 10 may exceed 1000 degrees Celsius. Although the following description focuses on the temperature difference between two locations, it should be understood that the system 12 and method 100 may be applied to any location throughout the exterior 14 of the flight vehicle 10. Thus, in the following description, the exterior 14 of the flight vehicle 10 includes a first exterior panel 16A and a second exterior panel 16B.

[0015]

[0023] Generally, in all of the configurations of Figures 3-6, the system 12 includes a fluid loop 32 configured to contain a working fluid 33. The fluid loop 32 is coupled to the skin panels 16, and thus the flight vehicle 10 may include a fluid loop 32 integrated along the skin panels 16. For purposes of the following example, the fluid loop 32 is coupled to the first skin panel 16A and the second skin panel 16B. Heat is thereby transferred from one or more of the skin panels 16 to the working fluid 33. The heated working fluid 33 is then transported through the fluid loop 32 and used to heat one or more other of the skin panels 16 in various ways, as described below in Figures 3-6. Thus, for example, the heat transferred from the first skin panel 16A reduces the temperature of the first skin panel 16A, and the heated working fluid 33 is used to increase the temperature of the second skin panel 16B. Thus, the temperature difference between the first skin panel 16A and the second skin panel 16B is reduced.

[0016]

[0024] The fluid loop 32 may be coupled to the skin panel 16 at any suitable location. For example, the fluid loop 32 may be disposed internally to or integral with the skin panel 16. As another example, the fluid loop 32 may be disposed externally to or adjacent to the skin panel 16. For illustrative purposes, FIG. 7 illustrates the fluid loop 32 internal to one or more of the skin panels 16, and FIG. 8 illustrates the fluid loop 32 external to one or more of the skin panels 16. Regardless of the location of the fluid loop 32, the fluid loop 32 is disposed inside the flight vehicle 10. As such, the fluid loop 32 is not visible from outside the flight vehicle 10. As such, the fluid loop 32 does not affect the aerodynamic characteristics of the flight vehicle 10.

[0017]

[0025] For example, as shown in FIG. 7, when the fluid loop 32 is internal to the exterior panel 16, the exterior panel 16 may include a plurality of apertures 34 that define the fluid loop 32. The apertures 34 are disposed between an exterior surface 36 and an interior surface 38 of the exterior panel 16. The apertures 34 may be of any suitable configuration, and non-limiting examples may include gyroid, cubic, diamond, triangular, random, circular, rectangular, wavy, or any other suitable configuration. Thus, in certain configurations, the apertures 34 create a porous structure through the exterior panel 16, and the porous structure of the fluid loop 32 may include a triple periodic minimal surface (gyroid), a lattice structure, or the like.

[0018]

[0026] 8, when the fluid loop 32 is external to the skin panel 16, the fluid loop 32 is attached to an inner surface 38 of the skin panel 16. Thus, when the fluid loop 32 is exterior to the skin 14 (exterior) to the skin panel 16, the fluid loop 32 passes over the skin panel 16 in a serpentine pattern, winding pattern, etc., relative to the inner surface 38 of the skin panel 16. The fluid loop 32 may include one or more tubes 40 attached to the inner surface 38 of the skin panel 16. The tubes 40 may be of any suitable configuration, and non-limiting examples may include circular, triangular, rectangular, or any other suitable configuration.

[0019]

[0027] In certain configurations, the fluid loop 32 is integrated into the windward skin panel 24 and the leeward skin panel 28. One or more of the mold lines 22 may be joined together with the exterior panels 16, such as the windward skin panel 24 and the leeward skin panel 28. Generally, the fluid loop 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 distortion at the mold line 22 is reduced or minimized. This reduces structural loads along the airframe of the flight vehicle 10. By reducing the structural loads along the airframe of the flight vehicle 10, the aerodynamic characteristics of the exterior 14 of the flight vehicle 10 may be improved and fuel leakage (fuel usage) may be minimized.

[0020]

[0028] Depending on the type of working fluid 33 used, the working fluid 33 may be in a supercritical state. For example, the working fluid 33 may be used in the fluid loop 32 due to the amount of heat generated by the flight vehicle 10 at high speed, and the amount of heat absorbed by the working fluid 33 maintains the working fluid 33 in a supercritical state. The working fluid 33 becomes supercritical when the temperature and pressure of the working fluid 33 exceed a critical point (see FIG. 2). Thus, heat from the exterior 14 of the flight vehicle 10 is transferred to the working fluid 33 in the fluid loop 32. This maintains the working fluid 33 at a temperature and pressure above the critical point. FIG. 2 graphically illustrates the critical point of the working fluid 33, where the temperature and pressure above the critical point result in a supercritical state. The working fluid 33 may be any suitable substance, some of which may be in a supercritical state and some of which may not. Non-limiting examples of working fluid 33 may include supercritical carbon dioxide, supercritical helium (sHe), molten salt(s), sodium-potassium alloy (NaK), cesium, lithium, etc. Thus, examples of working fluid 33 that reach a supercritical state may include carbon dioxide, helium, etc. Examples of working fluid 33 that do not reach a supercritical state may include molten salt(s), sodium-potassium alloy (NaK), cesium, lithium, etc.

[0021]

[0029] When the flight vehicle 10 is moving at a flight speed of at least Mach 3, the first skin panel 16A is at a first initial temperature and the second skin panel 16B is at a second initial temperature. The first initial temperature is higher than the second initial temperature, and a temperature difference between the first initial temperature and the second initial temperature defines an initial temperature difference. The fluid loop 32 is coupled to the first skin panel 16A and the second skin panel 16B. Heat is thereby transferred from the first skin panel 16A to the working fluid 33 to reduce the first initial temperature of the first skin panel 16A to a first modified temperature and to heat the working fluid 33. The heated working fluid 33 is circulated from the first skin panel 16A and used to heat the second skin panel 16B to a second modified temperature that is higher than the second initial temperature. The temperature difference between the first modified temperature and the second modified temperature defines a second temperature difference that is smaller than the initial temperature difference. The system 12 is activated to redistribute heat in light of the initial temperature difference to achieve a second temperature difference, which causes the exterior panels 16 to be closer in temperature to one another than would be the case without the use of the system 12 and method 100 described herein. Reducing the temperature difference between the exterior panels 16 helps to alleviate thermal distortion along the mold lines 22, which can reduce adverse structural loads caused by thermal distortion. Reducing the temperature difference between the exterior panels 16 also reduces thermal stresses across various components of the flight vehicle 10, allowing different materials with lower temperature properties to be used for the various components of the flight vehicle 10.

[0022]

[0030] Optionally, in any of the configurations herein, the system 12 may include a number of sensors 42 (see FIG. 1 ) disposed along the exterior 14 of the flight vehicle 10. More specifically, one or more of the sensors 42 may be disposed along the exterior panel 16. The sensor 42 may be integrated into the exterior panel 16 or may be disposed along the inner surface 38 of the exterior panel 16. The sensor 42 is configured to provide information about the temperature of the exterior 14, and more specifically, about the temperature at various locations on the exterior panel 16. This temperature information may be used to monitor the temperature of the exterior 14 and / or to determine where to redistribute heat throughout the flight vehicle 10. For example, the sensor 42 may be of any suitable configuration, and non-limiting examples may include a temperature sensor that measures the actual temperature of the exterior 14 and / or a strain sensor that measures the thermal strain of the exterior 14 to determine the temperature of the exterior 14.

[0023]

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

[0024]

[0032] For illustrative purposes, some additional skin panels 16 and sensors 42 are briefly described. FIG. 9 shows a schematic representation of multiple skin panels 16 and multiple sensors 42 for the purposes of this description. Again, the description herein may apply to any suitable number of skin panels 16 and sensors 42, and FIG. 9 is for illustrative purposes. Thus, in certain configurations, the skin 14 may include a third skin panel 16C and a fourth skin panel 16D. The fluid loop 32 may be coupled to the third skin panel 16C and the fourth skin panel 16D. Thus, the fluid loop 32 may be coupled to the first, second, third, and / or fourth skin panels 16A, 16B, 16C, 16D. Optionally, the sensor 42 may further include a third sensor 42C and a fourth sensor 42D. Thus, in certain configurations, a third sensor 42C may be coupled to the third skin panel 16C and a fourth sensor 42D may be coupled to the fourth skin panel 16D. The third sensor 42C may measure a third initial temperature and a third modified temperature of the third skin panel 16C. The fourth sensor 42D may measure a fourth initial temperature and a fourth modified temperature of the fourth skin panel 16D. Thus, the third sensor 42C may be a temperature sensor or a strain sensor or any other suitable sensor for providing information about the temperature at various locations of the skin panel 16, and similarly, the fourth sensor 42D may be a temperature sensor or a strain sensor or any other suitable sensor for providing information about the temperature at various locations of the skin panel 16.

[0025]

[0033] The system 12 may also include a controller 44 (FIG. 1) in communication with the sensor 42 to receive information about the temperature of the exterior 14. The controller 44 may use the information from the sensor 42 to monitor the temperature of the exterior 14, determine where to redistribute heat throughout the flight vehicle 10, and / or control other components of the system 12. It should be understood that the controller 44 may also be used to perform other functions, some of which are described herein.

[0026]

[0034] Returning to the sensors 42, for example, the controller 44 may communicate with a first sensor 42A to receive information about a first initial temperature and a first modified temperature of the first skin panel 16A, and with a second sensor 42B to receive information about a second initial temperature and a second modified temperature of the second skin panel 16B. This is so for as many sensors 42 as are being used. That is, the controller 44 may communicate with each of the sensors 42 and with the first, second, third, and / or fourth sensors 42A, 42B, 42C, 42D, etc. The controller 44 may use the information about the temperature of the skin 14 to determine where to redistribute heat throughout the skin 14 of the flight vehicle 10, thus achieving a more uniform skin temperature of the skin 14.

[0027]

[0035] In certain configurations, the system 12 may include a number of valves 46 coupled to the fluid loop 32. The valves 46 may direct the heated working fluid 33 to selected locations on the exterior 14 of the flight vehicle 10, such as the exterior panels 16. Thus, for example, one or more of the valves 46 may be opened or closed to direct the heated working fluid 33 to desired locations throughout the exterior panels 16. Generally, the controller 44 is in communication with the valves 46. The controller 44 is configured to control the opening or closing of the valves 46 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 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. In one embodiment of the above, it is assumed that the first exterior panel 16A is a panel such as: That is, heat is taken from a first skin panel 16A and redistributed to a second skin panel 16B, a third skin panel 16C, and / or a fourth skin panel 16D, etc. It should be understood that two or more skin panels 16 can be such panels 16, 24, 28, that is, heat is taken from skin panels 16, 24, 28 and redistributed to others of the skin panels 16.

[0028]

[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, or the like.

[0029]

[0037] Returning to the controller 44, instructions may be stored in the memory M of the controller 44 and may be automatically executed by the processor P of the controller 44 to provide the respective control functions. The controller 44 is thus configured to execute instructions from the memory M by the processor P. For example, the controller 44 may be a host machine or a distributed system, for example a computer such as a digital computer or a microcomputer, and a tangible non-transitory computer readable medium such as a read-only memory (ROM) or a flash memory (as the memory M). 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) circuitry, as well as any necessary input / output circuitry and associated devices, and any necessary signal conditioning and / or signal buffering circuitry. Thus, the controller 44 may include, for example, all the software, firmware, hardware, memory M, algorithms, connections, sensors, etc. necessary to control, monitor and make decisions regarding the valves 46, sensors 42, and other components coupled to the fluid loop 32, as described below. It should be understood that the controller 44 may also include any device capable of analyzing data from various sensors, comparing the data, and making the decisions necessary to control and / or monitor the valves 46, sensors 42, and other components coupled to the fluid loop 32, as described below. Optionally, more than one controller 44 may be utilized.

[0030]

[0038] For example, hardware for the controller 44 may include one or more processors P coupled to a current driver. The one or more processors P may include any electronic and / or optical circuitry capable of performing the functions described herein. For example, the processor(s) P may perform any of the functions described herein for the controller 44. The processor(s) 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 the processors P include INTEL® CORE™ processors, advanced reduced instruction set computing (RISK) machine (ARM®) processors, etc.

[0031]

[0039] Heat from the exterior 14 of the flight vehicle 10 may be redistributed in many different ways, some examples of which are described below. Figures 3-6 show several non-limiting examples of redistributing heat throughout the exterior 14 of the flight vehicle 10, some of which are described below.

[0032]

[0040] 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 high pressure. Thus, depending on the type of working fluid 33, the compressor 48 compresses the working fluid 33 to a pressure above the critical point. The compressor 48 is disposed along the fluid loop 32 within the flight vehicle 10 and may be located at various points depending on the configuration.

[0033]

[0041] The controller 44 receives feedback from one or more of the sensors 42, and the controller 44 is programmed to start the compressor 48 when the exterior 14 of the flight vehicle 10 exceeds a threshold temperature. Non-limiting exemplary threshold temperatures for starting the compressor 48 may include about 500 degrees Celsius to about 1000 degrees Celsius. In other embodiments, the controller 44 uses information about the flight speed of the flight vehicle 10 to determine whether to start the compressor 48. The information is indicative of the temperature of the exterior 14 of the flight vehicle 10. The controller 44 starts the compressor 48 when the flight vehicle 10 reaches the threshold flight speed. Non-limiting exemplary threshold flight speeds for starting the compressor 48 may include Mach 3, Mach 3.5, Mach 4, and hypersonic speeds.

[0034]

[0042] 3 and 5 , the system 12 may include a heat inlet 50 configured to absorb heat from the first exterior panel 16A and transfer the heat to the fluid loop 32 for heating the working fluid 33. Generally, the heat inlet 50 may be a section of the fluid loop 32 that is thermally coupled to the exterior 14, such as the exterior panel 16. Additionally, the system 12 may include a heat outlet 51 configured to transfer heat from the fluid loop 32 to the second exterior panel 16B.

[0035]

[0043] Continuing with FIGS. 3 and 5, the system 12 may also include a heat engine 52 disposed downstream from the heat inlet 50. The heat engine 52 is coupled to the compressor 48 and configured to operate the compressor 48. For example, the heat engine 52 and the compressor 48 may be mechanically or electrically coupled to one another. In one embodiment, the heat engine 52 includes a shaft 54 ​​coupled to the compressor 48. Thus, a work output 56 from the heat engine 52 may be transferred to the compressor 48 via the shaft 54, or the work output 56 may be transferred to the compressor 48 via an electrical connection. Regardless of how the work output 56 is coupled to the compressor 48, the work output operates the compressor 48. Thus, for example, the heat engine 52 may generate torque as the work output 56. The work output 56 is transferred to the compressor 48 via the shaft 54. The use of supercritical working fluid 33 allows the compressor 48, heat engine 52, and other components along the fluid loop 32 to be smaller and lighter.

[0036]

[0044] Generally, the compressor 48 and the heat engine 52 divide the fluid loop 32 into a low pressure leg 58 and a high pressure leg 60. The low pressure leg 58 is downstream of the heat engine 52 at an inlet side 62 of the compressor 48, and the high pressure leg 60 is upstream of the heat engine 52 at an outlet side 64 of the compressor 48. Thus, the heat engine 52 may operate to extract work output 56 from the working fluid 33 by expanding the working fluid 33 to a low pressure.

[0037]

[0045] Generally, the heat engine 52 is disposed within the flight vehicle 10 along the fluid loop 32 and downstream of the thermal inlet 50. The heat engine 52 may be of any suitable configuration configured to transfer torque and / or extract work output 56 from the pressurized working fluid 33. Non-limiting examples may include a turbine, a scroll expander, a thermoelectric converter, a thermionic converter, or any other suitable heat engine 52.

[0038]

[0046] Continuing with the configuration of Figure 3, 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 electrical power. The electrical power may be used to operate an auxiliary load, the engine-generator 66, or any other type of load.

[0039]

[0047] 3 , the system 12 may optionally include a recuperator 68 disposed along the fluid loop 32 and coupled to the low pressure leg 58 downstream of the turbine and coupled to the high pressure leg 60 downstream at the output of the compressor 48. The recuperator 68 is configured to transfer heat from the low pressure leg 58 of the fluid loop 32 to the high pressure leg 60 of the fluid loop 32. Generally, the recuperator 68 may increase the thermal efficiency of the system 12. Thus, the recuperator 68 may operate as a heat exchanger. Transferring heat to the working fluid 33 by the recuperator 68 prior to further heating the working fluid 33 by the heat inlet 50 increases the temperature of the working fluid 33 entering the heat engine 52. This increases the amount of work output 56 that may be extracted from the working fluid 33.

[0040]

[0048] Continuing with the configuration of FIG. 3, the system 12 may include a precooler 70 disposed along the fluid loop 32 and coupled to the low pressure leg 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 may ensure that the temperature of the working fluid 33 does not exceed an operating temperature range for the compressor 48. The excess heat from the precooler 70 may be exhausted or rejected to the surrounding atmosphere or transferred to a second fluid in a heat sink loop 72 for another system of the flight vehicle 10. In certain configurations, the precooler 70 may include a precooling heat exchanger 74. Thus, the heat sink loop 72 transfers the excess heat from the precooler 70 to a storage structure containing the second fluid or to a thermal energy storage device. The second fluid in the heat sink loop 72 may be any suitable fluid, and non-limiting examples may include a fuel, such as a hydrocarbon fuel (e.g., Jet-A, JP-8, JP-10, kerosene, RP2, etc.) or a cryogenic fuel (e.g., liquid hydrogen, liquid natural gas, etc.), water, or other types of fluids disposed within the flight vehicle 10.

[0041]

[0049] Referring again to FIG. 3, the fluid loop 32 forms a first loop 32A and a second loop 32B that are isolated from each other. The first loop 32A and the second loop 32B each contain a working fluid 33. The working fluid 33 of the first loop 32A and the second loop 32B can be any of the substances described above. In certain configurations, the working fluid 33 of the first loop 32A is different from the working fluid 33 of the second loop 32B. For example, the first loop 32A can contain a working fluid 33 that is a first substance, and the second loop 32B can contain a working fluid 33 that is a second substance that is different from the first substance. As another example, in certain configurations, the working fluid 33 of the first loop 32A is in a supercritical state, and the working fluid 33 of the second loop 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 loop 32A and the second loop 32B. Thus, for example, the working fluid 33 may be in a supercritical state in both the first loop 32A and the second loop 32B. In the configuration of Figure 3, the first loop 32A may be referred to as the high pressure loop and the second loop 32B may be referred to as the low pressure loop.

[0042]

[0050] The system 12 may also include a heat exchanger 76 (see FIG. 3 ) coupled to the first loop 32A and the second loop 32B. Generally, the heat exchanger 76 is disposed downstream of the turbine and upstream of the recuperator 68. Heat from the working fluid 33 of the first loop 32A is transferred by the heat exchanger 76 to the second loop 32B to heat the second skin panel 16B. That is, heat from the working fluid 33 of the first loop 32A is transferred by the heat exchanger 76 to the working fluid 33 of the second loop 32B to heat the working fluid 33 of the second loop 32B. The second loop 32B then transports the heated working fluid 33 to the desired skin panel 16 to heat or increase the temperature of that skin panel 16.

[0043]

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

[0044]

[0052] Continuing with Figure 3, the various skin panels 16, such as the first skin panel 16A, as well as the heat inlet 50, the heat engine 52, and the first compressor 48A are coupled to a first loop 32A. The second loop 32B is coupled to the various skin panels 16, such as the second skin panel 16B, as well as a second compressor 78. The second compressor 78 is disposed along the second fluid loop 32 between the heat exchanger 76 and the skin panel 16 to be heated.

[0045]

[0053] Turning to the configuration of FIG. 4, the fluid loop 32 is a closed loop between the various skin panels 16. In this configuration, heat from the skin 14 is transferred to the working fluid 33, which reduces the temperature of the skin panel 16. The heated working fluid 33 is then transferred to another one of the skin panels 16 by the compressor 48, which increases the temperature of the other one of the skin panels 16. Thus, heat from a first skin panel 16A can be transferred to the working fluid 33 by the heat inlet 50. Heat from the heated working fluid 33 can be transferred to a second skin panel 16B by the heat outlet 51. Thus, for example, a closed loop can be disposed between the first skin panel 16A, the second skin panel 16B, and the compressor 48. Thereby, the heated working fluid 33 is circulated directly from the first exterior panel 16A to the second exterior panel 16B, causing the second exterior panel 16B to be heated to a second changed temperature that is higher than the second initial temperature.

[0046]

[0054] Turning to the configuration of Figure 5, the system 12 may include the heat inlet 50, heat engine 52, compressor 48, recuperator 68, generator 66, and precooler 70, as described above for the configuration of Figure 3. Some of these are repeated for Figure 5, but see above for a detailed description of these features.

[0047]

[0055] 5, a heat engine 52 is disposed downstream of the heat inlet 50, the heat engine 52 being operable to generate a work output 56 as described above. Thus, a compressor 48 and a generator 66 may be coupled to the heat engine 52, whereby the compressor 48 and the generator 66 may use a portion of the work output 56. A recuperator 68 is disposed along the fluid loop 32 and is coupled to the low pressure leg 58 downstream of the turbine and coupled to the downstream high pressure leg 60 at the output of the compressor 48. A precooler heat exchanger 74 of a precooler 70 is coupled to the low pressure leg 58 upstream of the compressor 48 and downstream of the recuperator 68.

[0048]

[0056] Continuing with FIG. 5 , the system 12 may include a heater 80 coupled to one or more of the skin panels 16. The heater 80 may be incorporated inside one or more of the skin panels 16 or may be disposed adjacent to the interior surface 38 of one or more of the skin panels 16. For example, the heater 80 may be coupled to the second skin panel 16B, which may be the skin panel 16 that is to be heated to a higher temperature. The heater 80 and the generator 66 are electrically connected to one another, such that power from the generator 66 may operate the heater 80. The generator 66 is operably coupled to the heat engine 52, such that the work output 56 from the heat engine 52 is used by the generator 66 to provide its power to the heater 80. This enables the heater 80 to heat the second skin panel 16B. That is, the temperature of the first skin panel 16A may be reduced by heat transferred to the working fluid 33. The heated working fluid 33 from the first exterior panel 16A is then transferred to the heat engine 52. The heat engine 52 uses the heat to generate work output 56 that is used by the generator 66. The generator 66 ultimately increases the temperature of the second exterior 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, tapes, cartridges, resistive heating, cylinders, cords, and the like. The generator 66 may be used to charge a battery. It should be understood that the battery may be used to power the heater 80 or to assist the generator 66 in powering the heater 80. In other configurations, the generator 66 may be replaced with a thermoelectric device used to power the heater 80.

[0049]

[0057] Continuing with Figure 5, the controller 44 may be in communication with the generator 66 and the heater 80. The controller 44 may use a variety of information, including information from the sensor 42, to determine when to operate the heater 80.

[0050]

[0058] Turning to the configuration of Figure 6, the fluid loop 32 is configured as a heat pipe 82 having an evaporator side 84 disposed along the windward skin panel 24 and a condenser side 86 disposed along the leeward skin panel 28. The evaporator side 84 and the condenser side 86 are connected to each other by a plurality of intermediate pipe connections 88. The evaporator side 84 is configured to heat the working fluid 33 for transfer of heat away from the windward skin panel 24. The heated working fluid 33 is transported through the intermediate pipe connections 88 to the condenser side 86 for transfer of heat to the leeward skin panel 28.

[0051]

[0059] In certain configurations, the heat pipe 82 is a thermal diode configuration. In the thermal diode configuration, the evaporator side 84 enhances heat transport directed toward the condenser side 86, and the condenser side 86 inhibits heat transport directed back toward the evaporator side 84. More specifically, the intermediate pipe connection 88 may include components or features for transferring the working fluid 33 between the sides 84, 86 and providing heat transfer to the sides 84, 86. Thus, the windward skin panel 24 is cooled while the leeward skin panel 28 is heated, reducing the temperature difference between various locations on the exterior 14 of the flight vehicle 10. That is, the temperature of the windward skin panel 24 decreases and the temperature of the leeward skin panel 28 increases. This reduces the temperature difference between the locations. It should be understood that the valve 46 may be located in any suitable location, and non-limiting examples may include valves along the fluid loop 32 on the evaporator side 84, the fluid loop 32 on the condenser side 86, and / or the intermediate pipe connection 88.

[0052]

[0060] Generally, the heat pipes 82 provide a passive manner to spread and transport the working fluid 33 to various locations along the aircraft skin 14. Various passive manners can be used to spread and transport the working fluid 33, non-limiting examples include gravity-driven, such as a thermosiphon, surface tension-driven, such as a heat pipe or vapor chamber. The heat pipes 82 may include a tube 40 that is integral or inseparable with the skin panel 16 or attached to the inner surface 38 of the skin panel 16. The heat pipes 82 may be of any suitable configuration, non-limiting examples may include an oscillating / pulsating heat pipe, a variable conductance heat pipe, or the like.

[0053]

[0061] The present disclosure also provides a method 100 for reducing temperature differentials across an exterior 14 of a flight vehicle 10. It is to be understood that the order or sequence of performing the method 100 as described below is for illustrative purposes, and that other orders or sequences are within the scope of the present teachings. It is also to be understood that the method 100 can include other features not specifically described immediately below.

[0054]

[0062] During flight of the flight vehicle 10, the exterior 14 may heat up due to aerodynamic forces. Once the flight vehicle 10 reaches a certain flight speed, it may be desirable to reduce the temperature differential across the exterior 14 of the flight vehicle 10. For example, as described herein, it may be desirable to reduce the temperature differential across the exterior 14 of the flight vehicle 10 via method 100 once the flight speed reaches at least Mach 3 or greater.

[0055]

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

[0056]

[0064] As discussed above, the exterior shell 14 can include a first exterior panel 16A at a first initial temperature and a second exterior panel 16B at a second initial temperature, and as discussed 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.

[0057]

[0065] The working fluid 33 is circulated through the fluid loop 32, and the working fluid 33 is used to transfer heat as described herein. The fluid loop 32 is coupled to the desired skin panel 16, and may be coupled to the first skin panel 16A and the second skin panel 16B, for example. Heat from the first skin panel 16A is transferred to the working fluid 33. This reduces the first initial temperature of the first skin panel 16A to a first modified temperature, and heats the working fluid 33. The heated working fluid 33 is circulated from the first skin panel 16A, and the heated working fluid 33 is used to heat the second skin panel 16B to a second modified temperature, which is higher than the second initial temperature. The temperature difference between the first modified temperature and the second modified temperature defines a second temperature difference that is smaller than the initial temperature difference. By reducing the temperature difference between various points of the skin 14, different types of materials may be used for various components of the flight vehicle 10. Also, by reducing the temperature differential between various locations on the exterior 14, the integrity along the mold lines 22 may be improved, which reduces thermal stresses and distortions in the airframe. Additionally, by reducing the temperature differential between various locations on the exterior 14, the flight vehicle 10 may be constructed of materials that have lower temperature characteristics.

[0058]

[0066] Referring to the configuration of FIG. 3, the fluid loop 32 forms a first loop 32A and a second loop 32B that are isolated from each other. The first loop 32A and the second loop 32B each contain a working fluid 33. The working fluid 33 of the first loop 32A is compressed by a first compressor 48. A heat engine 52 is operatively coupled to the first compressor 48 to operate the first compressor 48. Heat is absorbed from the first skin panel 16A by a heat inlet 50, and the heat is transferred to the first loop 32A to heat the working fluid 33. That is, the working fluid 33 absorbs heat from the first skin panel 16A by the heat inlet 50. The first skin panel 16A, the heat inlet 50, the heat engine 52, and the first compressor 48 are coupled to the first loop 32A. The working fluid 33 of the second loop 32A is compressed by the second compressor 78. Heat is transferred by the heat exchanger 76 from the working fluid 33 of the first loop 32A to the working fluid 33 of the second loop 32B to heat the second exterior panel 16B. More specifically, the heated working fluid 33 of the first loop 32A transfers heat by the heat exchanger 76 to the working fluid 33 of the second loop 32B. As discussed above, the controller 44 may be in communication with various components of the configuration of FIG. 3, such as the optional sensors 42, the optional valves 46, the generator 66, the first compressor 48A, and the second compressor 78.

[0059]

[0067] Returning to the configuration of Figure 4, the fluid loop 32 is a closed loop between the first skin panel 16A, the second skin panel 16B, and the compressor 48. In this configuration, circulating the heated working fluid 33 may further include circulating the heated working fluid 33 directly from the first skin panel 16A to the second skin panel 16B to heat the second skin panel 16B to a second modified temperature that is higher than the second initial temperature. As discussed above, the controller 44 may be in communication with various components of the configuration of Figure 4, such as the optional sensor 42, the optional valve 46, and the compressor 48.

[0060]

[0068] Referring to the configuration of FIG. 5 , the working fluid 33 is compressed by the compressor 48. Heat is absorbed from the first skin panel 16A by the heat inlet 50, and the heat is transferred to the fluid loop 32 to heat the working fluid 33. The heat engine 52 is operably coupled to the generator 66. Thereby, the work output 56 from the heat engine 52 is used by the generator 66 to provide electrical power. Further, 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 electrical power from the generator 66 may be used by the heater 80 to operate the heater 80. The heater 80 coupled to the second skin panel 16B is operated by the electrical power from the generator 66 to warm the second skin panel 16B. That is, the operation of the heater 80 may increase the temperature of the second skin panel 16B. As mentioned above, the controller 44 may be in communication with various components of the configuration of FIG. 5, such as the optional sensors 42, the optional valves 46, the generator 66, the compressor 48, the heater, etc.

[0061]

[0069] Returning to the configuration of FIG. 6, as described above, the first skin panel 16A may include the windward skin panel 24 disposed along the lower surface 26 of the flight vehicle 10, and the second skin panel 16B may include the leeward skin panel 28 disposed along the upper surface 30 of the flight vehicle 10. The fluid loop 32 is configured as a heat pipe 82. The heat pipe 82 may include an evaporator side 84 disposed along the windward skin panel 24 and a condenser side 86 disposed along the leeward skin panel 28. The evaporator side 84 and the condenser side 86 are connected to each other by a pipe connection. In this configuration, circulating the heated working fluid 33 may further include passively circulating the heated working fluid 33 from the evaporator side 84 away from the windward skin panel 24 through an intermediate pipe connection 88 to the condenser side 86 to transfer heat to the leeward skin panel 28. As mentioned above, the controller 44 may be in communication with various components of the configuration of FIG. 6, such as the optional sensors 42, the optional valves 46, etc.

[0062]

[0070] While the best mode and several alternative configurations for carrying out the present disclosure have been described in detail, those skilled in the art to which the disclosure pertains will recognize numerous alternative designs and configurations for carrying out the present disclosure within the scope of the appended claims. Moreover, the features of the various configurations shown in the drawings or described in this description need not necessarily be understood as mutually independent embodiments. Rather, each feature described in one of the configuration examples can be combined with one or more other desired features from the other configurations, resulting in other configurations not described by words or by reference to the drawings. Such other configurations are therefore included within the framework of the appended claims.

[0063]

[0071] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is not in fact capable of performing that particular function without any modification, but rather may perform that particular function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing that particular function. As used herein, the term "configured to" refers to the existing characteristics of a system, device, structure, article, element, component, or hardware that enable the system, device, structure, article, element, component, or hardware to perform a particular function without further modification. In this disclosure, a system, apparatus, structure, article, element, component, or hardware described as being "configured" to perform a particular function may additionally or alternatively be described as being "adapted to" and / or "operative to" perform that function.

[0064]

[0072] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. These illustrations are not intended to exhaustively describe all elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may become apparent to those skilled in the art upon review of this disclosure. Other embodiments may be utilized and derived from this disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Thus, the present disclosure and the drawings should be regarded as illustrative rather than restrictive.

[0065]

[0073] The following provisions provide some example configurations of the system 12, flight vehicle 10, and method 100 as disclosed herein.

[0066]

[0074] Article 1. 1. A system for reducing a temperature difference across an aircraft vehicle traveling at a flight speed of at least Mach 3, the system comprising: an exterior of the aircraft vehicle including a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature, the first initial temperature being greater than the second initial temperature, a temperature difference between the first initial temperature and the second initial temperature defining an initial temperature difference; and a fluid loop configured to contain a working fluid, the fluid loop 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 modified temperature and to heat the working fluid, the heated working fluid being circulated from the first exterior panel and used to heat the second exterior panel to a second modified temperature higher than the second initial temperature, the temperature difference between the first modified temperature and the second modified temperature defining a second temperature difference less than the initial temperature difference.

[0067]

[0075] Article 2. The system described in clause 1, further comprising a plurality of sensors including a first sensor coupled to the first exterior panel for measuring the first initial temperature and the first modified temperature, and a second sensor coupled to the second exterior panel for measuring the second initial temperature and the second modified temperature.

[0068]

[0076] Article 3. The system described in clause 1 or 2, further comprising a controller in communication with the first sensor and the second sensor to receive information about the first initial temperature and the first modified temperature of the first exterior panel, and the second initial temperature and the second modified temperature of the second exterior panel.

[0069]

[0077] Article 4. The system of any one of clauses 1 to 3, wherein the exterior includes a third exterior panel and a fourth exterior panel, the fluid loop is coupled to the third exterior panel and the fourth exterior panel, the plurality of sensors further includes a third sensor coupled to the third exterior panel and a fourth sensor coupled to the fourth exterior panel, the system further includes a plurality of valves coupled to the fluid loop, and the controller communicates with the valves such that the controller is configured to control opening and closing of the plurality of valves to direct the heated working fluid to one or more of the second exterior panel, the third exterior panel, and the fourth exterior panel based on information from one or more of the first sensor, the second sensor, the third sensor, and the fourth sensor.

[0070]

[0078] Article 5. 5. The system of any one of clauses 1 to 4, further comprising a compressor configured to compress the working fluid.

[0071]

[0079] Article 6. 6. The system of any one of clauses 1 to 5, further comprising a heat inlet configured to absorb heat from the first exterior panel and transfer the heat to the fluid loop to heat the working fluid, and a heat engine coupled to a compressor and configured to operate the compressor, the heat engine disposed downstream of the heat inlet.

[0072]

[0080] Article 7. The system of any one of clauses 1 to 6, wherein the fluid loops form a first loop and a second loop isolated from each other, the first loop containing the working fluid being a first material and the second loop containing the working fluid being a second material different from the first material, the first exterior panel, the heat inlet, the heat engine, and the compressor are coupled to the first loop and the second loop is coupled to the second exterior panel, and the system further comprises a heat exchanger coupled to the first loop and the second loop, and heat from the working fluid in the first loop is transferred by the heat exchanger to the second loop to heat the second exterior panel.

[0073]

[0081] Article 8. 8. The system of any one of clauses 1 to 7, wherein the compressor is further defined as a first compressor, and the system further comprises a second compressor coupled to the second loop and configured to compress the working fluid.

[0074]

[0082] Article 9. 7. The system of any one of clauses 1 to 6, further comprising a heater coupled to the second exterior panel, and a generator operably coupled to the heat engine such that work output from the heat engine is used by the generator to provide power to the heater enabling the heater to heat the second exterior panel.

[0075]

[0083] Article 10. The system of any one of clauses 1 to 5, wherein the fluid loop is a closed loop between the first exterior panel, the second exterior panel, and a compressor such that the heated working fluid is circulated directly from the first exterior panel to the second exterior panel to heat the second exterior panel to the second changed temperature which is higher than the second initial temperature.

[0076]

[0084] Article 11. The system of any one of clauses 1 to 4, wherein the first exterior panel includes a windward skin panel disposed along an underside of the flight vehicle, and the second exterior panel includes a leeward skin panel disposed along an upper surface of the flight vehicle.

[0077]

[0085] Article 12. 12. The system of any one of clauses 1 to 4 or 11, wherein the fluid loop is integrated into the windward skin panel and the leeward skin panel.

[0078]

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

[0079]

[0087] Article 14. 14. The system of any one of clauses 1 to 4 or 11 to 13, wherein the fluid loop is configured as a heat pipe including an evaporator side disposed along the windward skin panel and a condenser side disposed along the leeward skin panel, the evaporator side and the condenser side connected to each other by a plurality of intermediate pipe connections, the evaporator side configured to heat the working fluid to transfer heat away from the windward skin panel, and the heated working fluid is transported through the plurality of intermediate pipe connections to the condenser side to transfer heat to the leeward skin panel.

[0080]

[0088] Clause 15. The system of any one of clauses 1 to 4 or 11 to 14, wherein the heat pipe is a thermal diode configuration in which the evaporator side enhances heat transport directed towards the condenser side and the condenser side inhibits heat transport directed back towards the evaporator side.

[0081]

[0089] Article 16. 1. A method for reducing a temperature differential across an exterior of an aircraft vehicle, comprising: advancing the aircraft vehicle at a flight speed of at least Mach 3, the exterior of the aircraft vehicle being aerodynamically heated by advancing the aircraft vehicle at the flight speed, the exterior including a first exterior panel at a first initial temperature and a second exterior panel at a second initial temperature, the first initial temperature being greater than the second initial temperature, a temperature difference between the first initial temperature and the second initial temperature defining an initial temperature difference; ... a first skin panel and a second skin panel; transferring heat from the first skin panel to the working fluid, whereby the first initial temperature of the first skin panel is reduced to a first modified temperature and the working fluid is heated; and circulating the heated working fluid from the first skin panel and using the heated working fluid to heat the second skin panel to a second modified temperature that is higher than the second initial temperature, where a temperature difference between the first modified temperature and the second modified temperature defines a second temperature difference that is less than the initial temperature difference.

[0082]

[0090] Article 17. 17. The method of claim 16, wherein the fluid loops form a first loop and a second loop isolated from each other, the first loop and the second loop each containing the working fluid, the method further comprising compressing the working fluid of the first loop by a first compressor, operably coupling a heat engine to the first compressor to operate the first compressor, absorbing heat from the first skin panel by a heat inlet and transferring the heat to the first loop to heat the working fluid, the first skin panel, the heat inlet, the heat engine, and the first compressor being coupled to the first loop, transferring the heat to the first loop, compressing the working fluid of the second loop by a second compressor, and transferring heat from the working fluid of the first loop to the working fluid of the second loop by a heat exchanger to heat the second skin panel.

[0083]

[0091] Article 18. 17. The method of claim 16, wherein the fluid loop is a closed loop between the first exterior panel, the second exterior panel, and a compressor, and circulating the heated working fluid further includes circulating the heated working fluid directly from the first exterior panel to the second exterior panel to heat the second exterior panel to the second changed temperature, which is higher than the second initial temperature.

[0084]

[0092] Article 19. 17. The method of claim 16, further comprising compressing the working fluid with a compressor; absorbing heat from the first skin panel by a heat inlet and transferring the heat to the fluid loop to heat the working fluid; operably coupling the heat engine to the generator such that work output from the heat engine is used by the generator to provide electrical power, the heat engine being coupled to the compressor to operate the compressor; and operably coupling the heat engine to the generator to operate a heater coupled to the second skin panel with electrical power from the generator to warm the second skin panel.

[0085]

[0093] Article 20. 17. The method of claim 16, wherein the first skin panel includes a windward skin panel disposed along an underside of the flight vehicle, and the second skin panel includes a leeward skin panel disposed along an upper surface of the flight vehicle, the fluid loop is configured as a heat pipe including an evaporator side disposed along the windward skin panel and a condenser side disposed along the leeward skin panel, the evaporator side and the condenser side connected to each other by a plurality of intermediate pipe connections, and circulating the heated working fluid further includes passively circulating the heated working fluid from the evaporator side through the plurality of intermediate pipe connections away from the windward skin panel to the condenser side to transfer heat to the leeward skin panel.

Claims

1. 1. A system (12) for reducing temperature differentials throughout an air vehicle (10) traveling at an airspeed of at least Mach 3, comprising: an exterior (14) of the flight vehicle (10) including a first exterior panel (16A) at a first initial temperature and a second exterior panel (16B) at a second initial temperature, the first initial temperature being greater than the second initial temperature, a temperature difference between the first initial temperature and the second initial temperature defining an initial temperature difference; and a fluid loop (32) configured to contain a working fluid (33), the fluid loop (32) being coupled to the first skin panel (16A) and the second skin panel (16B) such that heat is transferred from the first skin panel (16A) to the working fluid (33) to reduce the first initial temperature of the first skin panel (16A) to a first modified temperature and to heat the working fluid (33); The heated working fluid (33) is circulated from the first exterior panel (16A) and used to heat the second exterior panel (16B) to a second modified temperature higher than the second initial temperature, a temperature difference between the first modified temperature and the second modified temperature defining a second temperature difference less than the initial temperature difference.

2. 2. The system of claim 1, further comprising a plurality of sensors including a first sensor coupled to the first exterior panel for measuring the first initial temperature and the first modified temperature, and a second sensor coupled to the second exterior panel for measuring the second initial temperature and the second modified temperature.

3. 3. The system of claim 2, further comprising a controller in communication with the first sensor and the second sensor to receive information about the first initial temperature and the first modified temperature of the first exterior panel and the second initial temperature and the second modified temperature of the second exterior panel.

4. the exterior (14) includes a third exterior panel (16C) and a fourth exterior panel (16D), the fluid loop (32) being coupled to the third exterior panel (16C) and the fourth exterior panel (16D); the plurality of sensors (42) further includes a third sensor (42C) coupled to the third exterior panel (16C) and a fourth sensor (42D) coupled to the fourth exterior panel (16D); 4. The system of claim 3, further comprising a plurality of valves coupled to the fluid loop, the controller being configured to control opening and closing of the plurality of valves to direct the heated working fluid to one or more of the second skin panel, the third skin panel, and the fourth skin panel, based on information from one or more of the first sensor, the second sensor, the third sensor, and the fourth sensor.

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

6. a heat inlet (50) configured to absorb heat from the first skin panel (16A) and transfer the heat to the fluid loop (32) for heating the working fluid (33); and 6. The system of claim 5, further comprising a heat engine coupled to the compressor and configured to operate the compressor, the heat engine being positioned downstream of the heat inlet.

7. The fluid loop (32) forms a first loop (32A) and a second loop (32B) isolated from each other, the first loop (32A) containing the working fluid (33) being a first material, and the second loop (32B) containing the working fluid (33) being a second material different from the first material; the first exterior panel (16A), the heat inlet (50), the heat engine (52), and the compressor (48) are coupled to the first loop (32A); the second loop (32B) is coupled to the second exterior panel (16B); 7. The system of claim 6, further comprising a heat exchanger coupled to the first loop and the second loop, wherein heat from the working fluid in the first loop is transferred by the heat exchanger to the second loop to heat the second exterior panel.

8. The compressor (48) is further defined as a first compressor (48A); 8. The system (12) of claim 7, further comprising a second compressor (78) coupled to the second loop (32B) and configured to compress the working fluid (33).

9. a heater (80) coupled to the second exterior panel (16B); and 7. The system of claim 6, further comprising a generator operatively coupled to the heat engine such that work output from the heat engine is used by the generator to provide electrical power to the heater that enables the heater to heat the second exterior panel.

10. 6. The system (12) of claim 5, wherein the fluid loop (32) is a closed loop between the first skin panel (16A), the second skin panel (16B), and the compressor (48) such that the heated working fluid (33) is circulated directly from the first skin panel (16A) to the second skin panel (16B) to heat the second skin panel (16B) to the second modified temperature, which is higher than the second initial temperature.

11. 2. The system (12) of claim 1, wherein the first skin panel (16A) includes a windward skin panel (24) disposed along a lower surface (26) of the flight vehicle (10) and the second skin panel (16B) includes a leeward skin panel (28) disposed along an upper surface (30) of the flight vehicle (10).

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

13. 13. The system of claim 12, wherein the exterior cladding includes a plurality of mold lines joining the windward skin panel and the leeward skin panel, and the fluid loop is integrated into the windward skin panel and the leeward skin panel adjacent the plurality of mold lines.

14. the fluid loop (32) is configured as a heat pipe (82) including an evaporator side (84) disposed along the windward skin panel (24) and a condenser side (86) disposed along the leeward skin panel (28); the evaporator side (84) and the condenser side (86) are connected to each other by a plurality of intermediate pipe connections (88); 12. The system (12) of claim 11, wherein the evaporator side (84) is configured to heat the working fluid (33) for transferring heat away from the windward skin panel (24), and the heated working fluid (33) is transported through the plurality of intermediate pipe connections (88) to the condenser side (86) for transferring heat to the leeward skin panel (28).

15. 15. The system of claim 14, wherein the heat pipe is in a thermal diode configuration, where the evaporator side enhances heat transport directed toward the condenser side and the condenser side inhibits heat transport directed back toward the evaporator side.

16. A method (100) for reducing temperature differentials across an exterior (14) of a flight vehicle (10), comprising: advancing the flight vehicle (10) at a flight speed of at least Mach 3, wherein the exterior (14) of the flight vehicle (10) is aerodynamically heated by advancing the flight vehicle (10) at the flight speed, the exterior (14) including a first exterior panel (16A) at a first initial temperature and a second exterior panel (16B) at a second initial temperature, the first initial temperature being greater than the second initial temperature, a temperature difference between the first initial temperature and the second initial temperature defining an initial temperature difference; circulating a working fluid (33) through a fluid loop (32), the fluid loop (32) being coupled to the first skin panel (16A) and the second skin panel (16B); transferring heat from the first skin panel (16A) to the working fluid (33), the heat transferring lowering the first initial temperature of the first skin panel (16A) to a first modified temperature and heating the working fluid (33); and Circulating the heated working fluid (33) from the first skin panel (16A) and using the heated working fluid (33) to heat the second skin panel (16B) to a second modified temperature higher than the second initial temperature, a temperature difference between the first modified temperature and the second modified temperature defining a second temperature difference that is less than the initial temperature difference.

17. the fluid loop (32) forms a first loop (32A) and a second loop (32B) isolated from each other, the first loop (32A) and the second loop (32B) each containing the working fluid (33); The method (100) comprises: compressing the working fluid (33) in the first loop (32A) with a first compressor (48A); further comprising operably coupling a heat engine (52) to the first compressor (48A) for operating the first compressor (48A); absorbing heat from the first skin panel (16A) by a heat inlet (50) and transferring the heat to the first loop (32A) for heating the working fluid (33), wherein the first skin panel (16A), the heat inlet (50), the heat engine (52), and the first compressor (48A) are coupled to the first loop (32B); compressing the working fluid (33) in the second loop (32B) with a second compressor (78); 17. The method (100) of claim 16, further comprising transferring heat from the working fluid (33) of the first loop (32A) to the working fluid (33) of the second loop (32B) by a heat exchanger (76) to heat the second skin panel (16B).

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

19. compressing said working fluid (33) by a compressor (48); absorbing heat from said first skin panel (16A) by a heat inlet (50) and transferring said heat to said fluid loop (32) for heating said working fluid (33); operatively coupling the heat engine (52) to a generator (66) such that work output (56) from the heat engine (52) is used by the generator (66) to provide electrical power, the heat engine (52) being coupled to the compressor (48) to operate the compressor (48); and 20. The method (100) of claim 16, further comprising operating a heater (80) coupled to the second skin panel (16B) with power from the generator (66) to heat the second skin panel (16B).

20. the first skin panel (16A) includes a windward skin panel (24) disposed along a lower surface (26) of the flight vehicle (10), and the second skin panel (16B) includes a leeward skin panel (28) disposed along a upper surface (30) of the flight vehicle (10); the fluid loop (32) is configured as a heat pipe (82) including an evaporator side (84) disposed along the windward skin panel (24) and a condenser side (86) disposed along the leeward skin panel (28); the evaporator side (84) and the condenser side (86) are connected to each other by a plurality of intermediate pipe connections (88); 17. The method (100) of claim 16, wherein circulating the heated working fluid (33) further comprises passively circulating the heated working fluid (33) from the evaporator side (84) through the plurality of intermediate pipe connections (88) away from the windward skin panel (24) to the condenser side (86) for transferring heat to the leeward skin panel (28).

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