Distributed cooling system and cooling method applied to high-speed long-endurance aircraft

Abstract

The invention provides a distributed cooling system and method applied to a high-speed long-endurance aircraft, the distributed cooling system comprises a cooling medium storage subsystem, a conveying subsystem, an injection subsystem, a pressure control subsystem and an exhaust subsystem, the cooling medium conveying subsystem comprises a main pipeline, a capillary network and a mounting plate, the main pipeline is respectively connected with the cooling medium storage subsystem and the capillary network, the capillary network is distributed in an air layer through a mounting plate, the distributed cooling medium injection subsystem is connected with the capillary network, and the distributed cooling medium injection subsystem is used for conveying a cooling medium to the capillary network through the main pipeline and injecting the cooling medium into the air layer. And the cooling medium cools the to-be-cooled area through flash evaporation heat absorption. By applying the technical scheme, the technical problems that in the prior art, the thermal load problem of a high-speed long-endurance aircraft is severe, available heat sinks are difficult to match with the thermal load of the whole aircraft due to limited existing heat sinks, and the weight of a thermal protection structure is large are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft thermal protection, and in particular to a distributed cooling system and a cooling method applied to a high-speed and long-endurance aircraft. Background Art

[0002] High-speed, long-endurance aircraft fly at high speeds, work for long hours, and have severe heat load problems. If traditional thermal protection methods are used, due to the limited heat sink, it is difficult to match the available heat sink with the heat load of the entire aircraft. At the same time, the thermal protection structure is heavy, and the weight cost is high. Summary of the invention

[0003] The present invention provides a distributed cooling system and cooling method for high-speed and long-flight aircraft, which can solve the technical problems in the prior art that the heat load problem of high-speed and long-flight aircraft is severe, the existing heat sinks are limited, resulting in difficulty in matching the available heat sinks with the heat load of the entire aircraft, and the weight of the thermal protection structure is large.

[0004] According to one aspect of the present invention, there is provided a distributed cooling system for high-speed and long-endurance aircraft, the aircraft comprising a plurality of areas to be cooled, each of the areas to be cooled comprising a heat wall, a heat insulation layer, an air layer and an aluminum alloy wall panel arranged in sequence, the distributed cooling system comprising a cooling medium storage subsystem, a cooling medium delivery subsystem, a distributed cooling medium injection subsystem, a pressure control subsystem and an exhaust subsystem, the cooling medium delivery subsystem comprising a main line, a capillary network and a mounting plate, the main line being connected to the cooling medium storage subsystem and the capillary network respectively, the capillary network being distributed in the air layer through the mounting plate, the distributed cooling medium injection subsystem being connected to the capillary network, the cooling medium storage subsystem being used to store liquid cooling medium, the distributed cooling medium injection subsystem being used to transport the cooling medium in the cooling medium storage subsystem to the capillary network through the main line, and injecting the cooling medium into the air layer through the capillary network, the cooling medium absorbing heat by flash evaporation to cool the area to be cooled, the pressure control subsystem being connected to the air layer for regulating the air pressure of the air layer, the exhaust subsystem being connected to the air layer for discharging the gas generated by flash evaporation from the air layer.

[0005] Furthermore, the cooling medium is water.

[0006] According to another aspect of the present invention, a cooling method for the distributed cooling system proposed in the present invention is provided, the method comprising:

[0007] Determine the target control pressure value of each air layer according to the convection heat exchange area of ​​the insulation layer close to the air layer in each area to be cooled and the corresponding target cooling temperature;

[0008] A one-dimensional heat conduction model is established for each area to be cooled, and the aluminum alloy wall panel is used as the cold side to determine the working temperature of the hot wall in each area to be cooled and the temperature of the side of the aluminum alloy wall panel away from the air layer;

[0009] The temperature of the side of the heat insulation layer close to the air layer in each area to be cooled is calculated based on the one-dimensional heat conduction model, the working temperature of the heat wall and the temperature of the side of the aluminum alloy wall panel far from the air layer;

[0010] Establish an energy equation for the cooling medium flow rate required to cool each area to be cooled;

[0011] Based on the temperature of the side of the insulation layer close to the air layer and the energy equation, an iterative calculation is performed to obtain the cooling medium flow required to cool each area to be cooled;

[0012] The pressure control subsystem adjusts the air pressure of each air layer to the corresponding target control pressure value, and the distributed cooling medium injection subsystem injects liquid cooling medium into the corresponding air layer according to the calculated cooling medium flow rate, and the cooling medium absorbs heat through flash evaporation to cool the cooling area;

[0013] The gas produced by flash evaporation is discharged from the air layer through the exhaust subsystem.

[0014] Furthermore, the temperature of the side of the insulation layer adjacent to the air layer is calculated according to the one-dimensional heat conduction model, the temperature of the heat wall and the temperature of the aluminum alloy wall panel by the following formula:

[0015]

[0016] In the above formula, δ1 represents the thickness of the insulation layer, δ2 represents the thickness of the aluminum alloy wall panel, λ1 represents the thermal conductivity of the insulation layer, λ2 represents the thermal conductivity of the aluminum alloy wall panel, h represents the convective heat transfer coefficient of the aluminum alloy wall panel, and t h represents the working temperature of the hot wall, t c It represents the temperature of the side of the aluminum alloy siding far away from the air layer, t1 represents the temperature of the side of the insulation layer close to the air layer, and t2 represents the temperature of the side of the aluminum alloy siding close to the air layer.

[0017] Furthermore, the energy equation for the cooling medium flow rate required for the area to be cooled is:

[0018]

[0019] φ4=h1(t1-t f )A,

[0020] Δφ=φ1-φ3-φ4,

[0021] In the above formula, φ1 represents the heat conduction of the insulation layer, A represents the convection heat transfer area of ​​the insulation layer close to the air layer, h1 represents the heat transfer coefficient of the insulation layer close to the air layer, h2 represents the heat transfer coefficient of the aluminum alloy siding away from the air layer, φ3 represents the radiation heat of the insulation layer close to the air layer, E b1 represents the radiation force of the insulation layer, E b2 represents the radiation force of the capillary network in the air layer and its mounting plate, A1 represents the radiation heat exchange area of ​​the insulation layer, A2 represents the area of ​​the capillary network in the air layer and its mounting plate, and X 1,2 represents the radiation angle coefficient, ε1 represents the surface emissivity of the insulation layer close to the air, ε2 represents the surface emissivity of the capillary network of the water evaporation system and its mounting plate, φ4 represents the convective heat transfer of the insulation layer, t f It represents the temperature of the air layer close to the insulation layer, and Δφ represents the heat injected into the air layer.

[0022] The technical solution of the present invention provides a distributed cooling system and cooling method for high-speed and long-endurance aircraft. The system is based on the high heat sink characteristics of the cooling medium and uses the flash evaporation of the cooling medium to absorb a large amount of heat to efficiently reduce the temperature of the cooled surface. The cooling medium used in the system is stored in liquid form at room temperature, has low requirements for installation space, and can be used in a large area of ​​the air layer inside the aircraft. It can not only control the body temperature at a lower value when a small amount of cooling medium is distributed into the air layer of different parts of the aircraft, but also greatly reduce the weight of the traditional thermal protection structure of the aircraft, and has good engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A one-dimensional heat conduction model of the area to be cooled provided according to a specific embodiment of the present invention is shown;

[0025] Figure 2 A schematic diagram of a cooling water flow estimation model provided according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0029] like Figure 1As shown, according to a specific embodiment of the present invention, a distributed cooling system 20 for high-speed and long-flight aircraft is provided. The aircraft includes a plurality of areas to be cooled 10, each of which includes a heat wall 1, a heat insulation layer 2, an air layer 3 and an aluminum alloy wall panel 4 arranged in sequence. The distributed cooling system 20 includes a cooling medium storage subsystem, a cooling medium delivery subsystem, a distributed cooling medium injection subsystem, a pressure control subsystem and an exhaust subsystem. The cooling medium delivery subsystem includes a main pipeline, a capillary network and a mounting plate. The main pipeline is connected to the cooling medium storage subsystem and the capillary network respectively. The capillary network is distributed in the air layer 3 through the mounting plate, the distributed cooling medium injection subsystem is connected to the capillary network, the cooling medium storage subsystem is used to store liquid cooling medium, the distributed cooling medium injection subsystem is used to transport the cooling medium in the cooling medium storage subsystem to the capillary network through the main pipeline, and inject it into the air layer 3 through the capillary network, the cooling medium cools the cooling area 10 by flash evaporation heat absorption, the pressure control subsystem is connected to the air layer 3, and is used to adjust the air pressure of the air layer 3, and the exhaust subsystem is connected to the air layer 3, and is used to discharge the gas generated by flash evaporation from the air layer 3. As a specific embodiment of the present invention, the cooling medium is water.

[0030] By applying this configuration, a distributed cooling system for high-speed and long-endurance aircraft is provided. The system is based on the high heat sink characteristics of the cooling medium and utilizes the large amount of heat absorption by the flash evaporation of the cooling medium to efficiently reduce the temperature of the cooled surface. The cooling medium used in this system is stored in liquid form at room temperature, and has low requirements for installation space. It can be used over a large area in the air layer inside the aircraft. It can not only control the body temperature at a lower value by distributing a small amount of cooling medium into the air layer of different parts of the aircraft, but also greatly reduce the weight of the traditional thermal protection structure of the aircraft, and has good engineering application prospects. Compared with the prior art, the technical solution of the present invention can solve the technical problems of the severe thermal load problem of high-speed and long-endurance aircraft in the prior art, and the limited existing heat sinks make it difficult to match the available heat sinks with the thermal load of the whole aircraft, and the weight of the thermal protection structure is large.

[0031] According to another aspect of the present invention, a cooling method for the distributed cooling system proposed in the present invention is provided, the method comprising:

[0032] Determine the target control pressure value of each air layer according to the convection heat exchange area of ​​the insulation layer close to the air layer in each area to be cooled and the corresponding target cooling temperature. If the cooling medium is water, it can be determined according to the saturated vapor pressure table of water;

[0033] A one-dimensional heat conduction model is established for each area to be cooled, with the aluminum alloy wall plate as the cold side, and the working temperature of the hot wall in each area to be cooled (e.g., 750°C) and the temperature of the side of the aluminum alloy wall plate away from the air layer (e.g., 25°C) are determined;

[0034] The temperature of the side of the heat insulation layer close to the air layer in each area to be cooled is calculated based on the one-dimensional heat conduction model, the working temperature of the heat wall and the temperature of the side of the aluminum alloy wall panel far from the air layer;

[0035] Establish an energy equation for the cooling medium flow rate required to cool each area to be cooled;

[0036] Based on the temperature of the side of the insulation layer close to the air layer and the energy equation, an iterative calculation is performed to obtain the cooling medium flow required to cool each area to be cooled;

[0037] The pressure control subsystem adjusts the air pressure of each air layer to the corresponding target control pressure value, and the distributed cooling medium injection subsystem injects liquid cooling medium into the corresponding air layer according to the calculated cooling medium flow rate, and the cooling medium absorbs heat through flash evaporation to cool the cooling area;

[0038] The gas produced by flash evaporation is discharged from the air layer through the exhaust subsystem.

[0039] By applying this method, a cooling method is provided. The method is based on the thermal control requirements of high-speed and long-endurance aircraft. The amount of cooling medium of the distributed cooling system under a given thermal environment and thermal control requirements is calculated through theoretical analysis and simulation analysis. The thermal control temperature requirements of the parts are achieved by changing the air pressure of the air layer at different parts of the aircraft. Based on this, a distributed cooling scheme for high-speed and long-endurance aircraft is designed. When a small amount of medium is introduced, the temperature of the aircraft can be controlled at a lower value that meets the cooling requirements according to the thermal control requirements. The thickness of the thermal insulation layer can also be greatly reduced, and the weight of thermal protection can be reduced. It has good engineering application prospects and provides technical support for the thermal management of long-endurance, reusable high-speed aircraft and aircraft development.

[0040] Furthermore, in the embodiment of the present invention, assuming that the cold side is an aluminum alloy wall panel, the temperature of the side of the insulation layer adjacent to the air layer is calculated according to the one-dimensional heat conduction model, the temperature of the hot wall and the temperature of the aluminum alloy wall panel by the following formula:

[0041]

[0042] In the above formula, δ1 represents the thickness of the insulation layer, δ2 represents the thickness of the aluminum alloy wall panel, λ1 represents the thermal conductivity of the insulation layer, λ2 represents the thermal conductivity of the aluminum alloy wall panel, h represents the convective heat transfer coefficient of the aluminum alloy wall panel, and t h represents the working temperature of the hot wall, t c It represents the temperature of the side of the aluminum alloy siding far away from the air layer, t1 represents the temperature of the side of the insulation layer close to the air layer, and t2 represents the temperature of the side of the aluminum alloy siding close to the air layer.

[0043] Based on the above embodiments, in the embodiments of the present invention, the model is simplified into an insulation layer and an aluminum alloy wall panel layer, with a cooling medium in the middle, such as water. It is assumed that the side of the insulation layer away from the air layer is a fixed heat source of 700°C, and the temperature of the side of the aluminum alloy wall panel close to the air layer is the maximum allowable temperature of 120°C. The two conditions of natural convection and insulation are considered respectively on the side of the aluminum alloy wall panel away from the air layer, and the required cooling medium flow rate is calculated.

[0044] like Figure 2 As shown in the figure, the heat transfer considered in the model is as follows: ① Heat φ1 enters the air layer from the heat source through the heat wall; ② The heat introduced from the heat wall is divided into two parts, namely radiation heat φ3 and convection heat φ4; ③ The heat inside the air layer flows out through two parts, namely the enthalpy increase of the cooling medium and the convection heat φ2 between the aluminum alloy wall panel and the outside (this value is zero under adiabatic conditions), so an energy equation can be established for estimation. Among them, Figure 2 In the formula, h' represents the enthalpy of the cooling medium at the inlet temperature and pressure, and h" represents the enthalpy of the cooling medium at the outlet temperature and pressure. Specifically, in the embodiment of the present invention, the energy equation for the cooling medium flow rate required for the cooling area is:

[0045]

[0046] φ4=h1(t1-t f )A,

[0047] Δφ=φ1-φ3-φ4,

[0048] In the above formula, φ1 represents the heat conduction of the insulation layer, A represents the convection heat transfer area of ​​the insulation layer close to the air layer, h1 represents the heat transfer coefficient of the insulation layer close to the air layer, h2 represents the heat transfer coefficient of the aluminum alloy siding away from the air layer, φ3 represents the radiation heat of the insulation layer close to the air layer, E b1 represents the radiation force of the insulation layer, E b2 represents the radiation force of the capillary network in the air layer and its mounting plate, A1 represents the radiation heat exchange area of ​​the insulation layer, A2 represents the area of ​​the capillary network in the air layer and its mounting plate, and X 1,2 represents the radiation angle coefficient, ε1 represents the surface emissivity of the insulation layer close to the air, ε2 represents the surface emissivity of the capillary network of the water evaporation system and its mounting plate, φ4 represents the convective heat transfer of the insulation layer, t f It represents the temperature of the air layer close to the insulation layer, and Δφ represents the heat injected into the air layer.

[0049] The iterative energy equation calculates the cooling medium flow rate required for the distributed cooling system. According to the cooling demand, the air layer cooling can be controlled under different temperature conditions by changing the ambient pressure of the air layer.

[0050] In summary, the present invention provides a distributed cooling system and cooling method for high-speed, long-flight aircraft. The system is based on the high heat sink characteristics of the cooling medium and utilizes the large amount of heat absorption by the flash evaporation of the cooling medium to efficiently reduce the temperature of the cooled surface. The cooling medium used in the system is stored in liquid form at room temperature, and has low requirements for installation space. It can be used over a large area in the air layer inside the aircraft. It can not only control the body temperature at a lower value by distributing a small amount of cooling medium into the air layer of different parts of the aircraft, but also greatly reduce the weight of the traditional thermal protection structure of the aircraft, and has good engineering application prospects. Compared with the prior art, the technical solution of the present invention can solve the technical problems of the severe thermal load problem of high-speed, long-flight aircraft in the prior art, and the limited existing heat sinks make it difficult to match the available heat sinks with the thermal load of the entire aircraft, and the weight of the thermal protection structure is large.

[0051] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0052] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A distributed cooling system for high-speed and long-flight aircraft, characterized in that: The aircraft includes a plurality of areas to be cooled, each of which includes a heat wall, a heat insulation layer, an air layer and an aluminum alloy wall panel arranged in sequence, the distributed cooling system includes a cooling medium storage subsystem, a cooling medium delivery subsystem, a distributed cooling medium injection subsystem, a pressure control subsystem and an exhaust subsystem, the cooling medium delivery subsystem includes a main line, a capillary network and a mounting plate, the main line is respectively connected to the cooling medium storage subsystem and the capillary network, the capillary network is distributed in the air layer through the mounting plate, the distributed cooling medium injection subsystem is The injection subsystem is connected to the capillary network, the cooling medium storage subsystem is used to store liquid cooling medium, the distributed cooling medium injection subsystem is used to transport the cooling medium in the cooling medium storage subsystem to the capillary network through the main pipeline, and inject it into the air layer through the capillary network, the cooling medium cools the area to be cooled by absorbing heat through flash evaporation, the pressure control subsystem is connected to the air layer, and is used to regulate the air pressure of the air layer, and the exhaust subsystem is connected to the air layer, and is used to discharge the gas generated by flash evaporation from the air layer.

2. The distributed cooling system according to claim 1, characterized in that: The cooling medium is water.

3. A cooling method for the distributed cooling system according to claim 1 or 2, characterized in that: The method comprises: Determine the target control pressure value of each air layer according to the convection heat exchange area of ​​the insulation layer close to the air layer in each area to be cooled and the corresponding target cooling temperature; Establishing a one-dimensional heat conduction model for each of the areas to be cooled, taking the aluminum alloy wall panel as the cold side, and determining the working temperature of the hot wall in each of the areas to be cooled and the temperature of the side of the aluminum alloy wall panel away from the air layer; Calculate the temperature of the side of the heat insulation layer close to the air layer in each of the to-be-cooled areas according to the one-dimensional heat conduction model, the working temperature of the heat wall and the temperature of the side of the aluminum alloy wall panel far from the air layer; Establishing an energy equation for the cooling medium flow rate required to cool each of the areas to be cooled; Iteratively calculating based on the temperature of the side of the heat insulation layer close to the air layer and the energy equation to obtain the cooling medium flow rate required to cool each of the areas to be cooled; The air pressure of each air layer is adjusted to the corresponding target control pressure value through the pressure control subsystem, and the liquid cooling medium is sprayed into the corresponding air layer according to the calculated cooling medium flow rate through the distributed cooling medium injection subsystem, and the cooling medium cools the area to be cooled by flash evaporation and heat absorption; The gas produced by flash evaporation is discharged from the air layer through an exhaust subsystem.

4. The method according to claim 3, characterized in that The temperature of the side of the thermal insulation layer adjacent to the air layer is calculated according to the one-dimensional heat conduction model, the temperature of the heat wall and the temperature of the aluminum alloy wall panel by the following formula: In the above formula, δ1 represents the thickness of the insulation layer, δ2 represents the thickness of the aluminum alloy wall panel, λ1 represents the thermal conductivity of the insulation layer, λ2 represents the thermal conductivity of the aluminum alloy wall panel, h represents the convective heat transfer coefficient of the aluminum alloy wall panel, and t h represents the working temperature of the hot wall, t c It represents the temperature of the side of the aluminum alloy siding far away from the air layer, t1 represents the temperature of the side of the insulation layer close to the air layer, and t2 represents the temperature of the side of the aluminum alloy siding close to the air layer.

5. The method according to claim 4, characterized in that The energy equation for the cooling medium flow rate required for the area to be cooled is: φ4=h1(t1-t f )A, Δφ=φ1-φ3-φ4, In the above formula, φ1 represents the heat conduction of the insulation layer, A represents the convection heat transfer area of ​​the insulation layer close to the air layer, h1 represents the heat transfer coefficient of the insulation layer close to the air layer, h2 represents the heat transfer coefficient of the aluminum alloy siding away from the air layer, φ3 represents the radiation heat of the insulation layer close to the air layer, E b1 represents the radiation force of the insulation layer, E b2 represents the radiation force of the capillary network in the air layer and its mounting plate, A1 represents the radiation heat exchange area of ​​the insulation layer, A2 represents the area of ​​the capillary network in the air layer and its mounting plate, and X 1,2 represents the radiation angle coefficient, ε1 represents the surface emissivity of the insulation layer close to the air, ε2 represents the surface emissivity of the capillary network of the water evaporation system and its mounting plate, φ4 represents the convective heat transfer of the insulation layer, t f It represents the temperature of the air layer close to the insulation layer, and Δφ represents the heat injected into the air layer.

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