Distributed cooling system and cooling method for high-speed long-endurance aircraft

Abstract

This invention provides a distributed cooling system and method for high-speed, long-endurance aircraft. The distributed cooling system includes a cooling medium storage subsystem, a delivery subsystem, an 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 both the cooling medium storage subsystem and the capillary network. The capillary network is distributed within the air layer via the mounting plate. The distributed cooling medium injection subsystem is connected to the capillary network and is used to deliver the cooling medium through the main pipeline to the capillary network and inject it into the air layer. The cooling medium cools the area to be cooled by absorbing heat through flash evaporation. This invention addresses the severe heat load problem in existing high-speed, long-endurance aircraft, where the limited availability of heat sinks makes it difficult to match the available heat sinks with the overall aircraft heat load, and the heavy weight of the thermal protection structure.

Description

Technical Field

[0001] This invention relates to the field of aircraft thermal protection technology, and in particular to a distributed cooling system and cooling method for high-speed, long-endurance aircraft. Background Technology

[0002] High-speed, long-endurance aircraft fly at high speeds and operate for long periods, resulting in severe thermal load issues. If traditional thermal protection methods are used, the limited number of heat sinks makes it difficult to match the available heat sinks with the overall thermal load of the aircraft. At the same time, the thermal protection structure is heavy, resulting in a significant weight cost. Summary of the Invention

[0003] This invention provides a distributed cooling system and cooling method for high-speed, long-endurance aircraft, which can solve the technical problems of severe heat load in high-speed, long-endurance aircraft, limited existing heat sinks leading to difficulty in matching available heat sinks with the overall aircraft heat load, and large weight of thermal protection structures.

[0004] According to one aspect of the present invention, a distributed cooling system for a high-speed, long-endurance aircraft is provided. The aircraft includes multiple areas to be cooled, each of which includes a heat wall, a heat insulation layer, an air layer, and an aluminum alloy panel arranged sequentially. 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 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 within the air layer 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 deliver the cooling medium in the cooling medium storage subsystem to the capillary network via the main pipeline and inject it into the air layer through the capillary network. The cooling medium cools the areas 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. The exhaust subsystem is connected to the air layer and is used to exhaust 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 aforementioned distributed cooling system of the present invention is provided, the method comprising:

[0007] The target control pressure value for each air layer is determined based on the convective heat transfer area of ​​the insulation layer on the side closest to the air layer in each area to be cooled and the corresponding target cooling temperature.

[0008] Establish a one-dimensional heat conduction model for each area to be cooled, with the aluminum alloy wall panel as the cold side, and determine the working temperature of the hot wall and the temperature of the aluminum alloy wall panel on the side away from the air layer in each area to be cooled.

[0009] The temperature of the insulation layer close to the air layer in each cooling zone is calculated based on the one-dimensional heat conduction model, the working temperature of the hot wall, and the temperature of the aluminum alloy wall panel on the side away from the air layer.

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

[0011] The required flow rate of cooling medium for each area to be cooled is obtained by iterative calculation based on the temperature and energy equations of the side of the insulation layer closest to the air layer.

[0012] The pressure control subsystem adjusts the air pressure of each air layer to the corresponding target control pressure value. The distributed cooling medium injection subsystem injects liquid cooling medium into the corresponding air layer according to the calculated cooling medium flow rate. The cooling medium cools and lowers the temperature of the area to be cooled by flash evaporation and heat absorption.

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

[0014] Furthermore, the temperature on the side of the insulation layer adjacent to the air layer is calculated using the following formula based on a one-dimensional thermal conductivity model, the temperature of the hot wall, and the temperature of the aluminum alloy wall panel:

[0015] ,

[0016] ,

[0017] In the above formula, Indicates the thickness of the insulation layer. Indicates the thickness of the air layer. Indicates the thermal conductivity of the insulation layer. The air layer represents the thermal conductivity, h represents the convective heat transfer coefficient of the aluminum alloy wall panel, and t represents the thermal conductivity of the air layer. h t represents the operating temperature of the hot wall. c t1 represents the temperature of the aluminum alloy wall panel away from the air layer, t2 represents the temperature of the insulation layer close to the air layer, and t2 represents the temperature of the aluminum alloy wall panel close to the air layer.

[0018] Furthermore, the energy equation for the required cooling medium flow rate in the region to be cooled is:

[0019] ,

[0020] ,

[0021] ,

[0022] In the above formula, ∅1 represents the heat conduction of the insulation layer, A represents the convective heat transfer area of ​​the insulation layer on the side closest to the air layer, h1 represents the heat transfer coefficient of the insulation layer on the side closest to the air layer, and ∅3 represents the radiative heat of the insulation layer on the side closest to the air layer. Indicates the radiative power of the insulation layer. This represents the radiative power of the capillary network and its mounting plate within the air layer. A1 represents the radiative heat transfer area of ​​the insulation layer, and A2 represents the area of ​​the capillary network and its mounting plate within the air layer. ε1 represents the emissivity of the surface of the insulation layer closest to the air, ε2 represents the emissivity of the capillary network of the water evaporation system and its mounting plate, and ∅4 represents the convective heat transfer of the insulation layer. f This indicates the temperature of the side of the air layer closest to the insulation layer. This indicates the heat injected into the air layer.

[0023] The present invention provides a distributed cooling system and method for high-speed, long-endurance aircraft. Based on the high heat sink characteristics of the cooling medium, this system utilizes the flash evaporation of the cooling medium to absorb a large amount of heat, thereby efficiently reducing the temperature of the cooled surface. The cooling medium used in this system is stored in liquid form at room temperature, requiring less installation space and allowing for large-area application within the aircraft's internal air layer. This not only enables the control of the aircraft's temperature at lower values ​​while distributing small amounts of cooling medium into different parts of the aircraft's air layer, but also significantly reduces the weight of the aircraft's traditional thermal protection structure, demonstrating promising engineering application prospects. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0025] Figure 1 A one-dimensional thermal conductivity model of the region to be cooled, according to a specific embodiment of the present invention, is shown;

[0026] 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 Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0030] like Figure 1As shown, according to a specific embodiment of the present invention, a distributed cooling system 20 for a high-speed, long-endurance aircraft is provided. The aircraft includes multiple cooling zones 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 sequentially. 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. A capillary network is distributed within air layer 3 via mounting plates. A distributed cooling medium injection subsystem is connected to the capillary network. A cooling medium storage subsystem stores liquid cooling medium. The distributed cooling medium injection subsystem delivers the cooling medium from the storage subsystem to the capillary network via a main pipeline and injects it into air layer 3. The cooling medium cools the area 10 to be cooled by absorbing heat through flash evaporation. A pressure control subsystem is connected to air layer 3 to regulate the air pressure. An exhaust subsystem is connected to air layer 3 to discharge the gas generated by flash evaporation from air layer 3. In a specific embodiment of the invention, the cooling medium is water.

[0031] This configuration provides a distributed cooling system for high-speed, long-endurance aircraft. Based on the high heat sink characteristics of the cooling medium, this system utilizes the flash evaporation of the cooling medium to absorb a large amount of heat, efficiently reducing the temperature of the cooled surfaces. The cooling medium used in this system is stored in liquid form at room temperature, requiring less installation space and allowing for large-area application within the aircraft's internal air layer. This not only enables the control of the aircraft's temperature at lower values ​​by distributing small amounts of cooling medium to different parts of the air layer, but also significantly reduces the weight of the aircraft's traditional thermal protection structure, demonstrating promising engineering application prospects. Compared with existing technologies, the technical solution of this invention can solve the severe heat load problems of high-speed, long-endurance aircraft, the limited availability of existing heat sinks leading to difficulties in matching the available heat sinks with the overall aircraft heat load, and the large weight of the thermal protection structure.

[0032] According to another aspect of the present invention, a cooling method for the aforementioned distributed cooling system of the present invention is provided, the method comprising:

[0033] The target control pressure value for each air layer is determined based on the convective heat transfer 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 of water.

[0034] Establish a one-dimensional thermal conduction model for each area to be cooled, with the aluminum alloy wall panel as the cold side, and determine 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 panel away from the air layer (e.g., 25°C).

[0035] The temperature of the insulation layer close to the air layer in each cooling zone is calculated based on the one-dimensional heat conduction model, the working temperature of the hot wall, and the temperature of the aluminum alloy wall panel on the side away from the air layer.

[0036] Establish the energy equation for the required flow rate of the cooling medium to cool each area to be cooled;

[0037] The required flow rate of cooling medium for each area to be cooled is obtained by iterative calculation based on the temperature and energy equations of the side of the insulation layer closest to the air layer.

[0038] The pressure control subsystem adjusts the air pressure of each air layer to the corresponding target control pressure value. The distributed cooling medium injection subsystem injects liquid cooling medium into the corresponding air layer according to the calculated cooling medium flow rate. The cooling medium cools and lowers the temperature of the area to be cooled by flash evaporation and heat absorption.

[0039] The gas generated by flash evaporation is discharged from the air layer through the exhaust subsystem.

[0040] This approach provides a cooling method based on the thermal control requirements of high-speed, long-endurance aircraft. Through theoretical and simulation analysis, it calculates the amount of cooling medium in a distributed cooling system under given thermal environment and thermal control requirements. By changing the air pressure in different parts of the aircraft, the thermal control temperature requirements of those parts are achieved. Based on this, a distributed cooling scheme for high-speed, long-endurance aircraft is designed. With a small amount of medium introduced, the aircraft temperature can be controlled to a lower value that meets cooling requirements, while also significantly reducing the thickness of the insulation layer and the weight of thermal protection. This method shows promising engineering application prospects and provides technical support for thermal management and development of long-endurance, reusable high-speed aircraft.

[0041] Furthermore, in this embodiment of the invention, assuming the cold side is an aluminum alloy wall panel, the temperature on the side of the insulation layer adjacent to the air layer is calculated using the following formula based on a one-dimensional thermal conductivity model, the temperature of the hot wall, and the temperature of the aluminum alloy wall panel: , In the above formula, Indicates the thickness of the insulation layer. Indicates the thickness of the air layer. Indicates the thermal conductivity of the insulation layer. The air layer represents the thermal conductivity, h represents the convective heat transfer coefficient of the aluminum alloy wall panel, and t represents the thermal conductivity of the air layer. k t represents the operating temperature of the hot wall. ct1 represents the temperature of the aluminum alloy wall panel away from the air layer, t2 represents the temperature of the insulation layer close to the air layer, and t3 represents the temperature of the aluminum alloy wall panel close to the air layer. Based on the above embodiments, in this embodiment of the invention, the model is simplified to an insulation layer and an aluminum alloy wall panel layer, with a cooling medium, such as water, in between. 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. Considering both natural convection and insulation conditions on the side of the aluminum alloy wall panel away from the air layer, the required cooling medium flow rate is calculated.

[0042] like Figure 2 As shown, the heat transfer considered in the model is as follows: ① Heat ∅1 enters the air layer from the heat source through the hot wall via heat conduction; ② The heat introduced from the hot wall is divided into two parts: radiant heat ∅3 and convective heat transfer ∅4; ③ The heat inside the air layer flows out through two parts: the enthalpy increase of the cooling medium and the convective heat transfer ∅2 between the aluminum alloy wall panel and the outside (this value is zero under adiabatic conditions). Therefore, an energy equation can be established for estimation. Figure 2 middle, This indicates the enthalpy of the cooling medium at the inlet temperature and pressure. This represents the enthalpy of the cooling medium at the outlet temperature and pressure. Specifically, in this embodiment of the invention, the energy equation for the required flow rate of the cooling medium in the area to be cooled is:

[0043] ,

[0044] ,

[0045] ,

[0046] ,

[0047] In the above formula, ∅1 represents the heat conduction of the insulation layer, A represents the convective heat transfer area of ​​the insulation layer on the side closest to the air layer, and h1 represents the heat transfer coefficient of the insulation layer on the side closest to the air layer. This indicates the radiant heat on the side of the insulation layer closest to the air layer. Indicates the radiative power of the insulation layer. This represents the radiative power of the capillary network and its mounting plate within the air layer. A1 represents the radiative heat transfer area of ​​the insulation layer, and A2 represents the area of ​​the capillary network and its mounting plate within the air layer. ε1 represents the emissivity of the surface of the insulation layer on the side closest to the air, and ε2 represents the emissivity of the capillary network of the water evaporation system and its mounting plate. This represents the convective heat transfer of the insulation layer, t f This indicates the temperature of the side of the air layer closest to the insulation layer. This indicates the heat injected into the air layer.

[0048] The required cooling medium flow rate of the distributed cooling system is calculated by iterative energy equation. Based on the cooling demand, the cooling of the air layer can be controlled under different temperature conditions by changing the ambient pressure of the air layer.

[0049] In summary, this invention provides a distributed cooling system and method for high-speed, long-endurance aircraft. Based on the high heat sink characteristics of the cooling medium, this system utilizes the flash evaporation of the cooling medium to absorb a large amount of heat, thereby efficiently reducing the temperature of the cooled surface. The cooling medium used in this system is stored in liquid form at room temperature, requiring less installation space and allowing for large-area application within the aircraft's internal air layer. This not only enables the control of the aircraft's temperature at lower values ​​by distributing small amounts of cooling medium into different parts of the air layer, but also significantly reduces the weight of the aircraft's traditional thermal protection structure, demonstrating promising engineering application prospects. Compared with existing technologies, the technical solution of this invention can solve the severe heat load problems of high-speed, long-endurance aircraft, the limited availability of existing heat sinks leading to difficulties in matching the available heat sinks with the overall aircraft heat load, and the large weight of the thermal protection structure.

[0050] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0051] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A distributed cooling system for application to a high-speed long-endurance aircraft, characterized in that, The aircraft comprises a plurality of regions to be cooled, each of the regions to be cooled comprising a hot wall, a thermal 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 pipeline, a capillary tube network and a mounting plate, the main pipeline being connected with the cooling medium storage subsystem and the capillary tube network respectively, the capillary tube network being distributed in the air layer through the mounting plate, the distributed cooling medium injection subsystem being connected with the capillary tube network, the cooling medium storage subsystem being used for storing liquid cooling medium, the distributed cooling medium injection subsystem being used for delivering the cooling medium in the cooling medium storage subsystem to the capillary tube network through the main pipeline and injecting the cooling medium into the air layer through the capillary tube network, the cooling medium cooling and lowering the temperature of the regions to be cooled through flash evaporation heat absorption, the pressure control subsystem being in communication with the air layer and being used for regulating the air pressure of the air layer, the exhaust subsystem being in communication with the air layer and being used for exhausting the gas generated by flash evaporation from the air layer.

2. The distributed cooling system of claim 1, wherein, The cooling medium is water.

3. Cooling method for the distributed cooling system according to claim 1 or 2, characterized in that, The method comprises: determining a target regulation pressure value of each air layer according to the convective heat transfer area of the thermal insulation layer close to the air layer in each region to be cooled and the corresponding target cooling temperature; establishing a one-dimensional heat conduction model of each region to be cooled, taking the aluminum alloy wall panel as the cold side, and determining the working temperature of the hot wall and the temperature of the aluminum alloy wall panel away from the air layer in each region to be cooled; calculating the temperature of the thermal insulation layer close to the air layer in each region to be cooled according to the one-dimensional heat conduction model, the working temperature of the hot wall and the temperature of the aluminum alloy wall panel away from the air layer; establishing an energy equation of the cooling medium flow required for cooling each region to be cooled; iteratively calculating the cooling medium flow required for cooling each region to be cooled based on the temperature of the thermal insulation layer close to the air layer and the energy equation; adjusting the air pressure of each air layer to the corresponding target regulation pressure value by the pressure control subsystem, and injecting liquid cooling medium into the corresponding air layer according to the calculated cooling medium flow by the distributed cooling medium injection subsystem, so that the cooling medium cools and lowers the temperature of the regions to be cooled through flash evaporation heat absorption; exhausting the gas generated by flash evaporation from the air layer by the exhaust subsystem.

4. The method of claim 3, wherein, 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 hot wall and the temperature of the aluminum alloy wallboard by the following formula: , , In the above formula, represents the thickness of the thermal insulation layer, represents the thickness of the air layer, represents the thermal conductivity of the thermal insulation layer, represents the thermal conductivity of the air layer, h represents the convective heat transfer coefficient of the aluminum alloy wall panel, t h represents the working temperature of the hot wall, t c represents the temperature of the aluminum alloy wall panel away from the air layer side, t1 represents the temperature of the thermal insulation layer close to the air layer side, and t2 represents the temperature of the aluminum alloy wall panel close to the air layer side.

5. The method of claim 4, wherein, The energy equation of the cooling medium flow required for cooling each region to be cooled is: ， ， ， ， In the above formula, ∅1 represents the heat conduction heat of the heat insulation layer, A represents the convective heat transfer area of the side of the heat insulation layer close to the air layer, h1 represents the heat transfer coefficient of the side of the heat insulation layer close to the air layer, ∅3 represents the radiation heat of the side of the heat insulation layer close to the air layer, represents the radiation force of the heat insulation layer, represents the radiation force of the capillary tube network and the installation plate thereof in the air layer, A1 represents the radiation heat transfer area of the heat insulation layer, A2 represents the area of the capillary tube network and the installation plate thereof in the air layer, and represents the radiation angle coefficient, represents the surface emissivity of the side of the heat insulation layer close to the air, and ε2 represents the surface emissivity of the capillary tube network and the installation plate thereof of the water evaporation system, represents the convective heat transfer amount of the heat insulation layer, represents the temperature of the side of the air layer close to the heat insulation layer, represents the heat injected into the air layer.

Images