An electrowetting fluid transmission adaptive active thermal protection device and its control method

Abstract

The present invention provides an electrowetting fluid transmission adaptive active thermal protection device and a control method thereof, comprising a skin coated on the outer surface of an aircraft, a liquid reservoir located on the inner side of the skin, a cooling medium filled in the liquid reservoir, a capillary tube connected to the liquid reservoir at one end and extending to the outer surface of the skin at the other end, and a control system. The capillary tube is a multi-layer structure, which includes a capillary wall, an electrode layer and a dielectric hydrophobic layer from the outside to the inside. The control system is used to collect the environmental parameters of the aircraft and obtain the current outer surface temperature of the skin. When the outer surface temperature of the skin is greater than the skin safety temperature, the size of the corresponding sucking electrical signal is obtained according to the outer surface temperature of the skin, and the corresponding sucking electrical signal is output to the electrode layer. The present invention can accurately control the supply of the cooling medium according to the temperature change of the outer surface of the aircraft skin, thereby reducing the consumption of the cooling medium while ensuring the maximum thermal protection effect, thereby increasing the payload of the aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft thermal protection, and in particular to an electrowetting fluid transmission adaptive active thermal protection device and a control method thereof. Background Art

[0002] During re-entry missions, high-speed vehicles experience a continuous and extremely harsh aerodynamic thermal environment, with surface temperatures ranging from 1000 to 3000 K. During this period, the vehicle must not only effectively withstand the thermal loads caused by extreme heat to prevent structural damage and ensure the normal operation of internal equipment, but also its leading edge is typically designed with a sharp shape to achieve a high lift-to-drag ratio, which is crucial for improving the vehicle's stability and efficiency during re-entry.

[0003] Drag reduction and heat dissipation are two core challenges in the design of high-speed aircraft. Drag reduction helps improve the lift-to-drag ratio, thereby reducing fuel consumption; while effective heat dissipation can reduce the weight burden of the thermal protection system, thereby increasing the payload capacity of the aircraft. From the perspective of improving the lift-to-drag ratio, it is mainly achieved through two strategies: increasing lift and reducing drag. However, given the many limitations of lift-increasing measures, drag reduction has gradually become a key technical path to improve the lift-to-drag ratio. On the other hand, during high-speed flight, the gas near the skin undergoes intense friction with the skin surface under strong compression, resulting in a large amount of kinetic energy being converted into heat energy, forming a significant aerodynamic heating phenomenon. Therefore, exploring new methods for reducing heat and drag in high-speed aircraft has become an indispensable requirement for the development of such aircraft technology.

[0004] Active heat and drag reduction technology, with its powerful cooling efficiency and ability to cope with complex and harsh flight conditions, has become the main strategy for aircraft to cope with aerodynamic heating and reduce drag. At present, the main active heat and drag reduction methods include convection cooling, spray cooling, film cooling, and sweat cooling. Among them, sweat cooling technology is particularly prominent. It uses liquid as a cooling medium, which can greatly enhance the cooling effect while effectively reducing the consumption of cooling medium. Therefore, sweat cooling is widely regarded as an important development direction of efficient and lightweight thermal protection technology. However, sweat cooling still has problems such as insufficient matching between the transport of cooling fluid and the heat and drag reduction requirements of the skin surface, and difficulty in adapting to the real-time changing flight conditions during the return of high-speed aircraft. Summary of the Invention

[0005] In response to the problems that existing thermal protection technologies are not sufficiently compatible with the requirements for heat reduction and drag reduction on the skin surface, and are difficult to adapt to the real-time changing flight conditions during the return process of high-speed aircraft, the present invention provides an electrowetting fluid transmission adaptive active thermal protection device and a control method thereof, which actively and accurately regulates the supply of cooling medium according to the temperature changes on the outer surface of the aircraft skin, thereby achieving precise thermal management under various flight conditions and improving the matching of thermal protection measures with actual needs.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] An electrowetting fluid transmission adaptive active thermal protection device, characterized by comprising a skin covering the outer surface of an aircraft, a liquid reservoir located inside the skin, a cooling medium filled in the liquid reservoir, a capillary tube having one end connected to the liquid reservoir and the other end extending to the outer surface of the skin, and a control system; the capillary tube has a multi-layer structure, comprising, from the outside to the inside, a capillary wall, an electrode layer, and a dielectric hydrophobic layer; the control system comprises:

[0008] A database for storing corresponding data sets of the aircraft's flight altitude, Mach number, initial temperature of the cooling medium and the corresponding skin outer surface temperature, the cooling medium temperature at the interface between the capillary tube and the mainstream, the skin temperature at the interface between the capillary tube and the mainstream, and the skin inner surface temperature;

[0009] The acquisition module is used to collect the flight altitude, Mach number and initial temperature of the cooling medium of the aircraft;

[0010] A query module is used to search the database for the corresponding skin outer surface temperature, the coolant temperature at the interface between the capillary tube and the mainstream, the skin temperature at the interface between the capillary tube and the mainstream, and the skin inner surface temperature based on the collected flight altitude, Mach number, and initial temperature of the coolant;

[0011] A judgment module is used to judge whether the outer surface temperature of the skin is greater than the skin safety temperature;

[0012] The control module is used to calculate the cooling medium supply flow rate to be provided based on the mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and calculate the sucking electrical signal strength to be output based on the mapping relationship between the cooling medium supply flow rate and the sucking electrical signal, and then output a control signal to the power supply module;

[0013] A power supply module, which is electrically connected to the electrode layer and is used to receive the control signal from the control module and output a corresponding sucking electrical signal to the electrode layer;

[0014] The mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate is:

[0015]

[0016] Among them, κ s is the thermal conductivity of the skin, S is the porosity of the skin, l is the total heat conduction length of the skin, dp is the inner diameter of the micropores of the skin, N is the number of micropores per unit area of ​​the skin, F is the flow rate of the cooling medium per unit time, t is the initial temperature of the cooling medium, t l is the cooling medium temperature at the contact surface between the capillary and the main flow, T is the outer surface temperature of the skin, T l is the skin temperature at the contact surface between the capillary and the mainstream, T0 is the skin inner surface temperature, λ1, λ2, λ3 are correlation coefficients;

[0017] The mapping relationship between the cooling medium supply flow rate and the sucking electrical signal is:

[0018] Where ρ is the density of the cooling medium, r is the inner diameter of the capillary, φ is the capillary inclination angle, μ is the viscosity of the cooling medium, γ is the surface tension of the gas-liquid two-phase, U is the suction electrical signal, g is the acceleration of gravity, and l is the capillary length.

[0019] Furthermore, the acquisition module includes a pressure altitude sensor for acquiring the flight altitude of the aircraft, a flight speed sensor for acquiring the Mach number of the aircraft, and a thermocouple for acquiring the initial temperature of the cooling medium.

[0020] Furthermore, the method for establishing the database is: simulating the flight altitude and Mach number of the aircraft in a wind tunnel device, saving the flight altitude, Mach number, initial temperature of the cooling medium and the corresponding detected skin outer surface temperature, cooling medium temperature at the contact surface between the capillary and the mainstream, skin temperature at the contact surface between the capillary and the mainstream, and skin inner surface temperature under a single test as a set of data, and repeating the test to establish the required database.

[0021] Furthermore, the mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and the mapping relationship between the cooling medium supply flow rate and the suction electrical signal are established by:

[0022] S1: Conduct simulated flight tests of the aircraft in a wind tunnel, during which the outer surface temperature of the skin is collected in real time;

[0023] S2: When the outer surface temperature of the skin is higher than the skin safety temperature, the power supply module outputs a suction electrical signal to the electrode layer. By adjusting the magnitude of the suction electrical signal until the outer surface temperature of the skin drops below the skin safety temperature, the cooling medium supply flow rate, the suction electrical signal, the initial temperature of the cooling medium, the cooling medium temperature at the contact surface between the capillary tube and the main flow, the skin temperature at the contact surface between the capillary tube and the main flow, and the inner surface temperature of the skin are obtained and saved as a set of data;

[0024] S3: Repeat the test to establish a mapping relationship between the suction electrical signal and the cooling fluid supply flow rate, as well as a mapping relationship between the cooling fluid supply flow rate and the skin outer surface temperature.

[0025] Furthermore, the electrode layer is sprayed onto the capillary wall by magnetron sputtering, and the dielectric hydrophobic layer is deposited on the electrode layer by vapor deposition.

[0026] Furthermore, the dielectric hydrophobic layer is made of polyparaxylene; the initial contact angle of the dielectric hydrophobic layer is 90°<θ0<110°, and after applying the sucking electrical signal, the contact angle of the dielectric hydrophobic layer is 0°<θ<90°.

[0027] Furthermore, the liquid storage tank includes a tank body with an opening at the top and a top plate installed at the top of the tank body to close the tank body. One end of the capillary tube penetrates to the outer surface of the skin and is flush with it, and the other end penetrates the top plate and extends into the cooling medium in the liquid storage tank.

[0028] Furthermore, it also includes a liquid storage tank for injecting cooling medium into the liquid storage pool, and the liquid storage tank is connected to the liquid storage pool through a cooling medium delivery channel.

[0029] Furthermore, the cooling medium is liquid water.

[0030] The control method of the electrowetting fluid transmission adaptive active thermal protection device described in any of the above items is characterized by comprising the following steps:

[0031] S1: When the aircraft is performing a flight mission, the acquisition module collects the aircraft's flight altitude, Mach number, and initial temperature of the cooling medium in real time;

[0032] S2: The query module searches the database for the corresponding skin outer surface temperature, the coolant temperature at the interface between the capillary tube and the main flow, the skin temperature at the interface between the capillary tube and the main flow, and the skin inner surface temperature based on the collected flight altitude, Mach number, and initial temperature of the coolant.

[0033] S3: The judgment module judges whether the skin outer surface temperature is greater than the skin safety temperature based on the found skin outer surface temperature;

[0034] S4: When the outer surface temperature of the skin is greater than the skin safety temperature, the control module calculates the cooling medium supply flow rate to be provided based on the mapping relationship between the outer surface temperature of the skin and the cooling medium supply flow rate, and calculates the sucking electrical signal strength to be output based on the mapping relationship between the cooling medium supply flow rate and the sucking electrical signal, and then outputs a control signal to the power supply module;

[0035] S5: After receiving the control signal from the control module, the power supply module outputs a corresponding sucking electrical signal to the electrode layer (220) to perform active thermal protection.

[0036] The beneficial effects of the present invention are as follows:

[0037] 1. This invention achieves high-precision control of the coolant supply by establishing a mapping relationship between the skin surface temperature and the suction electrical signal. This means that the cooling level can be dynamically adjusted according to actual needs, ensuring that the aircraft surface temperature remains within the ideal range, improving the accuracy and efficiency of thermal management. Furthermore, the wires connected to the electrode layers in each capillary are independent, meaning that the control system can independently control the coolant flow rate entering each capillary, thereby implementing a regional coolant supply strategy and greatly improving coolant utilization.

[0038] 2. This invention utilizes electrowetting technology for fluid transfer, an innovative approach that eliminates the need for traditional mechanical pumps, reduces system complexity and weight, and increases the payload capacity of aircraft. Electrowetting regulates the flow of coolant by altering electrical signals, improving coolant transport efficiency. It is particularly well-suited for high-speed aircraft environments that require dynamic response and lightweight design.

[0039] 3. By precisely controlling the supply of cooling fluid, this invention reduces unnecessary energy consumption and improves the energy efficiency of the entire thermal management system. This is of great significance for extending aircraft endurance, reducing fuel consumption, and lowering operating costs.

[0040] 4. Compared with mechanical pump systems, the electrowetting fluid transmission system in the present invention reduces the number of moving parts, has a lower failure rate and higher reliability, which not only improves the working stability of the system, but also simplifies maintenance work and reduces long-term operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the structure of the electrowetting fluid transmission adaptive active thermal protection device according to an embodiment of the present invention.

[0042] Figure 2 4 is a cross-sectional view of a capillary tube according to an embodiment of the present invention.

[0043] Figure 3 This is a flow chart for establishing the mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and the mapping relationship between the cooling medium supply flow rate and the suction electrical signal as described in the embodiment of the invention.

[0044] Figure 4 This is a control flow chart of the electrowetting fluid transmission adaptive active thermal protection device according to an embodiment of the present invention.

[0045] The reference numerals are as follows:

[0046] 1-skin; 2-capillary; 210-capillary wall; 220-electrode layer; 230-dielectric hydrophobic layer; 3-liquid storage tank; 301-top plate; 302-tank body; 4-cooling medium delivery channel; 5-liquid storage tank. DETAILED DESCRIPTION

[0047] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0048] The electrowetting fluid transmission adaptive active thermal protection device described in this embodiment includes a skin 1 covering the outer surface of an aircraft, a liquid reservoir 3 located inside the skin 1, a cooling medium filled in the liquid reservoir 3, a capillary 2 with one end connected to the liquid reservoir 3 and the other end extending to the outer surface of the skin 1, and a control system. Figure 1 Schematic diagram of the structure of the electrowetting fluid transmission adaptive active thermal protection device described in this embodiment.

[0049] The capillary 2 is a multi-layer structure, which includes a capillary wall 210, an electrode layer 220 and a dielectric hydrophobic layer 230 from the outside to the inside. Figure 2 It is a cross-sectional view of the capillary described in this embodiment. The electrode layer 220 is sprayed onto the capillary wall 210 by magnetron sputtering. The dielectric hydrophobic layer 230 is made of polyparaxylene, and the dielectric hydrophobic layer 230 is deposited on the electrode layer 220 by vapor deposition. The liquid reservoir 3 includes a pool body 302 with an open top and a top plate 301 installed on the top of the pool body 302 to close the pool body 302. One end of the capillary 2 penetrates to the outer surface of the skin 1 and is flush with it, and the other end penetrates the top plate 301 and extends into the cooling medium in the liquid reservoir 3. The liquid storage tank 5 is used to fill the liquid reservoir 3 with a cooling medium, which is liquid water. The liquid storage tank 5 is connected to the liquid reservoir 3 through a cooling medium delivery channel 4.

[0050] The control system includes: a database for storing corresponding data sets of the aircraft's flight altitude, Mach number, initial temperature of the cooling medium and the corresponding skin outer surface temperature, the cooling medium temperature at the contact surface between the capillary tube and the mainstream, the skin temperature at the contact surface between the capillary tube and the mainstream, and the skin inner surface temperature; an acquisition module including an air pressure altitude sensor for acquiring the aircraft's flight altitude, a flight speed sensor for acquiring the aircraft's Mach number, and a thermocouple for acquiring the initial temperature of the cooling medium; a query module for searching the database for the corresponding skin outer surface temperature, capillary tube temperature, and initial temperature of the cooling medium based on the acquired flight altitude, Mach number, and initial temperature of the cooling medium. The cooling medium temperature at the contact surface with the mainstream, the skin temperature at the contact surface between the capillary and the mainstream, and the skin inner surface temperature; judgment module: used to judge whether the skin outer surface temperature is greater than the skin safety temperature; control module: used to calculate the cooling medium supply flow rate to be provided based on the mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and calculate the sucking electric signal strength to be output based on the mapping relationship between the cooling medium supply flow rate and the sucking electric signal, and then output the control signal to the power supply module; power supply module: this module is electrically connected to the electrode layer 220, and is used to receive the control signal sent by the control module, and output the corresponding sucking electric signal to the electrode layer 220.

[0051] The mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate is:

[0052]

[0053] Among them, κ s is the thermal conductivity of the skin, S is the porosity of the skin, l is the total heat conduction length of the skin, dp is the inner diameter of the micropores of the skin, N is the number of micropores per unit area of ​​the skin, F is the flow rate of the cooling medium per unit time, t is the initial temperature of the cooling medium, t l is the cooling medium temperature at the contact surface between the capillary and the main flow, T is the outer surface temperature of the skin, T l is the skin temperature at the contact surface between the capillary and the mainstream, T0 is the skin inner surface temperature, λ1, λ2, λ3 are correlation coefficients;

[0054] The mapping relationship between the cooling medium supply flow rate and the sucking electrical signal is:

[0055] Where ρ is the density of the cooling medium, r is the inner diameter of the capillary, φ is the capillary inclination angle, μ is the viscosity of the cooling medium, γ is the surface tension of the gas-liquid two-phase, U is the suction electrical signal, g is the acceleration of gravity, and l is the capillary length.

[0056] Furthermore, the database establishment method comprises simulating the flight altitude and Mach number of an aircraft in a wind tunnel apparatus, storing the flight altitude, Mach number, initial coolant temperature, and corresponding detected skin outer surface temperature, coolant temperature at the interface between the capillary tube and the mainstream, skin temperature at the interface between the capillary tube and the mainstream, and skin inner surface temperature from a single test as a set of data, and repeating the test to establish the required database. The wind tunnel apparatus is equipped with a first infrared thermal imager for detecting the skin outer surface temperature, and the aircraft is equipped with a second infrared thermal imager for detecting the coolant temperature at the interface between the capillary tube and the mainstream, the skin temperature at the interface between the capillary tube and the mainstream, and the skin inner surface temperature.

[0057] The mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and the mapping relationship between the cooling medium supply flow rate and the suction electrical signal are established as follows:

[0058] S1: Conduct simulated flight tests of the aircraft in a wind tunnel, during which the outer surface temperature of the skin is collected in real time;

[0059] S2: When the outer surface temperature of the skin is greater than the skin safety temperature, the power supply module outputs a sucking electrical signal to the electrode layer (220), and by adjusting the magnitude of the sucking electrical signal until the outer surface temperature of the skin drops below the skin safety temperature, the cooling medium supply flow, the sucking electrical signal, the initial temperature of the cooling medium, the cooling medium temperature at the contact surface between the capillary tube and the mainstream, the skin temperature at the contact surface between the capillary tube and the mainstream, and the skin inner surface temperature are obtained at this moment and stored as a set of data;

[0060] S3: Repeat the test to establish a mapping relationship between the suction electrical signal and the cooling fluid supply flow rate, as well as a mapping relationship between the cooling fluid supply flow rate and the skin outer surface temperature. Figure 3 This is a flow chart for establishing the mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and the mapping relationship between the cooling medium supply flow rate and the suction electrical signal described in this embodiment.

[0061] The electrowetting fluid transfer adaptive active thermal protection device described in this embodiment utilizes the electrowetting effect—that is, the effect of changing the wettability between a liquid and a solid surface through an applied electric field—to dynamically control the flow of the coolant within the microstructured capillary 2. Specifically, this embodiment utilizes a specially designed dielectric hydrophobic layer 230, which initially exhibits a large contact angle θ0 (90° < θ0 < 110°). This prevents the coolant from wetting the inner wall of the capillary 2, thereby preventing effective transfer of the coolant. During this phase, the system is in a non-operating state and does not provide active thermal protection. When the outer surface temperature of the skin 1 exceeds the safe temperature of the skin 1, the control system applies a suction electrical signal to the electrode layer 220. As the signal intensity increases, the originally hydrophobic surface of the dielectric hydrophobic layer 230 gradually transforms into a hydrophilic one, and the contact angle θ of the dielectric hydrophobic layer 230 gradually decreases (0° < θ < 90°). This transition is crucial because it causes the inner wall of the capillary 2 to shift from repelling the coolant to attracting it, creating conditions for subsequent heat exchange. Once the dielectric hydrophobic layer 230 transitions to a hydrophilic state, the wettability of the inner wall of the capillary tube 2 increases. Leveraging the Laplace pressure difference at the gas-liquid interface (the pressure difference generated by the curved surface), the coolant rapidly fills the capillary tube 2 and seeps out of the outer surface of the skin 1. Due to the high-speed external airflow, the coolant encounters resistance as it seeps out of the outer surface of the skin 1, resulting in a slow flow rate. Therefore, the seeping coolant forms a stagnant coating on the outer surface of the skin 1, thickening the fluid boundary layer and forming a continuous liquid film. Subsequently, under the continuous action of the electric field, the coolant flows along the capillary tube wall 210, ultimately "sweating" through the capillary tube 2 to form an air film on the outer surface of the skin 1, achieving the purpose of reducing heat and drag.

[0062] The control method of the electrowetting fluid transmission adaptive active thermal protection device comprises the following steps:

[0063] S1: When the aircraft is performing a flight mission, the acquisition module collects the aircraft's flight altitude, Mach number, and initial temperature of the cooling medium in real time;

[0064] S2: The query module searches the database for the corresponding skin outer surface temperature, the coolant temperature at the interface between the capillary tube and the main flow, the skin temperature at the interface between the capillary tube and the main flow, and the skin inner surface temperature based on the collected flight altitude, Mach number, and initial temperature of the coolant.

[0065] S3: The judgment module judges whether the skin outer surface temperature is greater than the skin safety temperature based on the found skin outer surface temperature;

[0066] S4: When the outer surface temperature of the skin is greater than the skin safety temperature, the control module calculates the cooling medium supply flow rate to be provided based on the mapping relationship between the outer surface temperature of the skin and the cooling medium supply flow rate, and calculates the sucking electrical signal strength to be output based on the mapping relationship between the cooling medium supply flow rate and the sucking electrical signal, and then outputs a control signal to the power supply module;

[0067] S5: After receiving the control signal from the control module, the power supply module outputs a corresponding sucking electrical signal to the electrode layer 220 to perform active thermal protection. Figure 4 This is a control flow chart of the electrowetting fluid transmission adaptive active thermal protection device described in this embodiment.

[0068] The electrowetting fluid-transfer adaptive active thermal device described in this embodiment can automatically assess thermal protection requirements under complex flight conditions. Based on real-time monitoring data of the outer surface temperature of the aircraft skin 1, the control system precisely regulates the strength of the suction electrical signal applied to the electrode layer 220, dynamically adjusting the flow rate of the cooling fluid within the capillary tubes 2 to precisely match the current heat dissipation requirements. This ensures maximum thermal protection effectiveness while optimizing resource utilization and avoiding energy waste caused by excessive cooling. Driven by the electrowetting effect, the cooling fluid rapidly flows along the network of capillaries 2 to the outer surface of the skin 1, where it forms a stable vapor or air film. This air film acts as a barrier, effectively isolating the skin 1 from direct contact with the surrounding high-temperature airflow, significantly reducing boundary layer frictional resistance and significantly lowering heat flux density, providing excellent thermal insulation and drag reduction for the aircraft surface. This mechanism not only improves flight efficiency but also extends the service life of key structural components, demonstrating the broad application potential and technological advancement of this adaptive thermal protection device in modern aviation and aerospace.

[0069] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. An electrowetting fluid transmission adaptive active thermal protection device, characterized in that: The invention comprises a skin (1) covering the outer surface of an aircraft, a liquid reservoir (3) located inside the skin (1), a cooling medium filled in the liquid reservoir (3), a capillary (2) having one end connected to the liquid reservoir (3) and the other end extending to the outer surface of the skin (1), and a control system; the capillary (2) is a multi-layer structure, comprising, from the outside to the inside, a capillary wall (210), an electrode layer (220), and a dielectric hydrophobic layer (230); the control system comprises: A database for storing corresponding data sets of the aircraft's flight altitude, Mach number, initial temperature of the cooling medium and the corresponding skin outer surface temperature, the cooling medium temperature at the interface between the capillary tube and the mainstream, the skin temperature at the interface between the capillary tube and the mainstream, and the skin inner surface temperature; The acquisition module is used to collect the flight altitude, Mach number and initial temperature of the cooling medium of the aircraft; A query module is used to search the database for the corresponding skin outer surface temperature, the coolant temperature at the interface between the capillary tube and the mainstream, the skin temperature at the interface between the capillary tube and the mainstream, and the skin inner surface temperature based on the collected flight altitude, Mach number, and initial temperature of the coolant; A judgment module is used to judge whether the outer surface temperature of the skin is greater than the skin safety temperature; The control module is used to calculate the cooling medium supply flow rate to be provided based on the mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and calculate the sucking electrical signal strength to be output based on the mapping relationship between the cooling medium supply flow rate and the sucking electrical signal, and then output a control signal to the power supply module; a power supply module, the module being electrically connected to the electrode layer (220), and being used to receive a control signal from the control module and output a corresponding sucking electrical signal to the electrode layer (220); The mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate is: Among them, κ s is the thermal conductivity of the skin, S is the porosity of the skin, l is the total heat conduction length of the skin, dp is the inner diameter of the micropores of the skin, N is the number of micropores per unit area of ​​the skin, F is the flow rate of the cooling medium per unit time, t is the initial temperature of the cooling medium, t l is the cooling medium temperature at the contact surface between the capillary and the main flow, T is the outer surface temperature of the skin, T l is the skin temperature at the contact surface between the capillary and the mainstream, T0 is the skin inner surface temperature, λ1, λ2, λ3 are correlation coefficients; The mapping relationship between the cooling medium supply flow rate and the sucking electrical signal is: Where ρ is the density of the cooling medium, r is the inner diameter of the capillary, φ is the capillary inclination angle, μ is the viscosity of the cooling medium, γ is the surface tension of the gas-liquid two-phase, U is the suction electrical signal, g is the acceleration of gravity, and l is the capillary length.

2. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The acquisition module includes a pressure altitude sensor for acquiring the flight altitude of the aircraft, a flight speed sensor for acquiring the Mach number of the aircraft, and a thermocouple for acquiring the initial temperature of the cooling medium.

3. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The database establishment method is as follows: simulating the flight altitude and Mach number of an aircraft in a wind tunnel device, saving the flight altitude, Mach number, initial temperature of the cooling medium and the corresponding detected skin outer surface temperature, cooling medium temperature at the contact surface between the capillary tube and the mainstream, skin temperature at the contact surface between the capillary tube and the mainstream, and skin inner surface temperature under a single test as a set of data, and repeating the test to establish the required database.

4. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The mapping relationship between the skin outer surface temperature and the cooling medium supply flow rate, and the mapping relationship between the cooling medium supply flow rate and the suction electrical signal are established as follows: S1: Conduct simulated flight tests of the aircraft in a wind tunnel, during which the outer surface temperature of the skin is collected in real time; S2: When the outer surface temperature of the skin is greater than the skin safety temperature, the power supply module outputs a sucking electrical signal to the electrode layer (220), and by adjusting the magnitude of the sucking electrical signal until the outer surface temperature of the skin drops below the skin safety temperature, the cooling medium supply flow, the sucking electrical signal, the initial temperature of the cooling medium, the cooling medium temperature at the contact surface between the capillary tube and the mainstream, the skin temperature at the contact surface between the capillary tube and the mainstream, and the skin inner surface temperature are obtained at this moment and stored as a set of data; S3: Repeat the test to establish a mapping relationship between the suction electrical signal and the cooling fluid supply flow rate, as well as a mapping relationship between the cooling fluid supply flow rate and the skin outer surface temperature.

5. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The electrode layer (220) is sprayed onto the capillary wall (210) by magnetron sputtering, and the dielectric hydrophobic layer (230) is deposited on the electrode layer (220) by vapor deposition.

6. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The material of the dielectric hydrophobic layer (230) is polyparaxylene; the initial contact angle of the dielectric hydrophobic layer (230) is 90°<θ0<110°; after applying a sucking electrical signal, the contact angle of the dielectric hydrophobic layer (230) is 0°<θ<90°.

7. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The liquid storage tank (3) comprises a tank body (302) with an open top and a top plate (301) installed at the top of the tank body (302) for closing the tank body (302); one end of the capillary tube (2) penetrates the outer surface of the skin (1) and is flush with it, and the other end penetrates the top plate (301) and extends into the cooling medium in the liquid storage tank (3).

8. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: It also includes a liquid storage tank (5) for injecting cooling medium into the liquid storage tank (3), and the liquid storage tank (5) is connected to the liquid storage tank (3) through a cooling medium delivery channel (4).

9. The electrowetting fluid transmission adaptive active thermal protection device according to claim 1, characterized in that: The cooling medium is liquid water.

10. The control method of the electrowetting fluid transmission adaptive active thermal protection device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: When the aircraft is performing a flight mission, the acquisition module collects the aircraft's flight altitude, Mach number, and initial temperature of the cooling medium in real time; S2: The query module searches the database for the corresponding skin outer surface temperature, the coolant temperature at the interface between the capillary tube and the main flow, the skin temperature at the interface between the capillary tube and the main flow, and the skin inner surface temperature based on the collected flight altitude, Mach number, and initial temperature of the coolant. S3: The judgment module judges whether the skin outer surface temperature is greater than the skin safety temperature based on the found skin outer surface temperature; S4: When the outer surface temperature of the skin is greater than the skin safety temperature, the control module calculates the cooling medium supply flow rate to be provided based on the mapping relationship between the outer surface temperature of the skin and the cooling medium supply flow rate, and calculates the sucking electrical signal strength to be output based on the mapping relationship between the cooling medium supply flow rate and the sucking electrical signal, and then outputs a control signal to the power supply module; S5: After receiving the control signal from the control module, the power supply module outputs a corresponding sucking electrical signal to the electrode layer (220) to perform active thermal protection.

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