Self-adaptive thermal protection device

Abstract

The invention discloses a self-adaptive thermal protection device which comprises a thermal insulation layer arranged on the outermost side; the heat insulation layer is of a porous ceramic structure; the upper surface of the bottom of the expansion cavity is provided with an expansion sleeve with the pressed volume changing. The expansion cavity is used for reducing external high heat flow; the outer wall of the vaporization area is made of a breathable material, and the vaporization area is filled with a liquid saturated working medium; the suction layer is of a porous network structure for generating capillary force on a gas-liquid interface of the suction layer in a high heat flow environment; the liquid storage cavity is filled with a cooling agent; during heating, the liquid saturated working medium in the expansion cavity is vaporized and enters the expansion cavity through the outer wall of the breathable material to provide pressure for the expansion sleeve so as to compress the cooling cavity to respond to the pressure change of the expansion cavity, and therefore stable output of a coolant is achieved. The device has the advantages of being compact in structure, rapid in response, capable of being repeatedly used and the like, and is suitable for thermal control protection application of long-endurance and high-Mach-number aircrafts in a cross-airspace complex thermal environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of hypersonic aircraft thermal protection, and in particular is an adaptive thermal protection device. Background Art

[0002] Hypersonic vehicles, particularly high-speed civil aviation and space transportation systems designed to achieve global travel within an hour, often face unique thermal protection challenges during long-duration flights, including extreme aerodynamic heating and limited cooling resources. Current thermal protection technologies can be categorized as passive, semi-passive, and active.

[0003] Compared to passive and semi-passive thermal protection, active thermal protection has advantages such as strong cooling capacity, the ability to withstand high heat fluxes for extended periods, and reusability. Among these, transpiration cooling technology has received widespread attention. This technology mimics the evaporation mechanism of human sweat. Through efficient convective heat transfer between a coolant and a porous medium, a continuous air film is formed on the heated surface, effectively increasing thermal resistance and thereby reducing the temperature of the heated surface. It is an effective means of coping with extreme heat load environments. To enhance the thermal protection effectiveness of transpiration cooling, a large number of experimental and theoretical studies have been devoted to revealing its heat and mass transfer mechanisms and optimizing its cooling performance under various working fluid and structural parameter conditions. In early studies, transpiration cooling systems generally used gas as the cooling medium. However, with the increase in the Mach number of hypersonic vehicles, the heat load increases significantly, making it difficult for transpiration cooling methods using gas cooling to meet cooling requirements.

[0004] Therefore, phase change cooling technology has gradually attracted attention in recent years. This technology uses liquid cooling medium to achieve higher cooling efficiency by utilizing the latent heat of evaporation, and can generate MW / m with very little working medium consumption. 2 The high-efficiency cooling and heat dissipation capability of the first level can provide an effective way to successfully cope with the above-mentioned severe heat load challenges, and has become an important development direction of the nose cone thermal protection technology of the new generation of long-endurance, high-speed aircraft. However, phase change sweating cooling technology faces many challenges in practical applications: the coolant flow rate is difficult to control, and the additional mass burden brought by precision pump control increases the aircraft load. At the same time, the technology itself is difficult to cope with the heat flux gradient distribution in the central area that is significantly higher than the periphery, and needs to rely on targeted structural design. In addition, the use of capillary-driven phase change sweating cooling technology is difficult to cope with extremely high heat fluxes and it is difficult to meet the needs of safe and efficient thermal protection. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an adaptive thermal protection device that can realize coolant delivery without increasing the load of the aircraft. It can cope with the thermal protection challenges of the front area of ​​the aircraft under conditions of large airspace and wide speed range, and meet the reuse requirements of repeated flight and high-maneuverability aircraft.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: An adaptive thermal protection device, comprising: A heat-insulating layer is provided on the outermost side; the heat-insulating layer is a porous ceramic structure; An expansion chamber connected to the bottom of the thermal insulation layer, with an expansion sleeve whose volume changes under pressure provided on the upper surface of the bottom of the expansion chamber; the expansion chamber is used to reduce the external high heat flow; A vaporization zone is provided inside the expansion chamber; the outer wall of the vaporization zone is made of a breathable material and the interior is filled with a liquid saturated working medium; A suction layer, the suction layer being located inside the thermal insulation layer, the suction layer being a porous network structure that generates capillary force at the air-liquid interface of the suction layer under a high heat flow environment; A liquid storage chamber, the liquid storage chamber is formed by the inner wall surface of the suction layer, the inner wall surface of the expansion chamber and the expansion sleeve; the liquid storage chamber is filled with a coolant; the coolant is transported to the thermal insulation layer through the porous network structure; when heated, the liquid saturated working medium in the expansion chamber vaporizes, enters the expansion chamber through the outer wall of the breathable material to provide pressure for the expansion sleeve, and is used to compress the cooling chamber, thereby realizing an adaptive cooling mechanism in which the greater the heat flow, the greater the pressure, and the greater the coolant flow rate, so as to respond to the pressure change of the expansion chamber and thereby achieve stable output of the coolant.

[0007] The adaptive thermal protection device provided by the present invention includes five key components: an insulation layer, a suction layer, an expansion chamber, a vaporization area, and a liquid storage chamber; the combination of these components constitutes a multifunctional composite cooling system with self-driving capabilities and adaptability to high heat flux density working conditions. It is suitable for application scenarios with extremely high thermal protection requirements, such as long-endurance hypersonic aircraft.

[0008] The thermal insulation layer is arranged at the outermost side of the direction of high-temperature heat flow in the aircraft. Its main function is to reduce the intensity of heat flow transmitted from the outside to the device and reduce the direct impact of the heat load on the internal suction layer and the liquid storage cavity, thereby effectively ensuring the structural stability of the device and the thermal utilization efficiency of the coolant. This layer is made of high-efficiency thermal insulation material, which not only has good low thermal conductivity, but also has a certain structural strength, and can withstand the complex effects of the coupled environment of mechanical shock and thermal shock under high-speed flight conditions. In addition, in order to enhance the overall cooling capacity of the device, the thermal insulation layer adopts a porous structure. While maintaining the thermal resistance function, it can provide an effective discharge channel for the vaporized coolant, which is conducive to the formation of a stable flow path for steam inside the device, thereby reducing flow resistance and improving exhaust efficiency.

[0009] The suction layer, located on the inner side of the thermal insulation layer, is responsible for absorbing and transporting the coolant. This layer utilizes a porous medium structure, and its pores form a stable gas-liquid interface after the coolant evaporates, generating capillary force that drives the coolant to actively draw liquid coolant from the liquid storage chamber to the heated surface area without an external pump, achieving self-driven transport, simplifying the device structure and reducing the aircraft load. At the same time, the porosity, pore size distribution, thickness and other parameters of the suction layer are gradient-optimized according to the specific heat flux gradient, enabling differentiated transport responses in different heat load areas, thereby improving the overall cooling efficiency and device thermal control capabilities.

[0010] In the expansion chamber, when external heat flux is transferred to the vaporization zone, the saturated liquid refrigerant absorbs heat and vaporizes within the enclosed expansion chamber, generating vapor pressure. This pressure drives the deformable expansion sleeve structure to expand, thereby squeezing the liquid storage chamber and achieving active pressurized delivery. This method not only utilizes capillary force to drive the coolant, but also utilizes thermally driven pressurization to push the expansion sleeve into the cooling chamber, increasing coolant flow and effectively addressing transient operating conditions such as sudden local heat flux surges in the aircraft.

[0011] The vaporization zone is located within the interior of the expansion chamber, with its outer wall made of a breathable material to ensure effective exchange between the gas and liquid phases. This region is filled with a liquid saturated working fluid. Under the action of high heat flux, the liquid saturated working fluid vaporizes, generating a large amount of steam. This steam is driven by a pressure differential to penetrate the breathable wall from the inside out and enter the expansion chamber. The vaporization zone design provides pressure to compress the cooling chamber, achieving an adaptive cooling mechanism where the greater the heat flux, the greater the pressure, and the greater the coolant flow rate, significantly improving the device's thermal protection and operational stability in extreme thermal environments.

[0012] The liquid storage cavity is the coolant storage and dynamic adjustment area in the device, and its structure is surrounded by the inner wall of the suction layer, the wall of the liquid storage cavity cylinder and the expansion sleeve structure. The interior of the cavity is filled with water or other high latent heat coolants, and has good sealing, compressibility and temperature regulation capabilities. It can dynamically adjust the chamber volume according to the thermal management needs of different stages during the flight. The expansion sleeve structure is a highly elastic polymer or a multi-layer composite elastomer. When driven by the vapor pressure in the vaporization zone, it produces a certain degree of deformation, thereby dynamically adjusting the cavity volume and enhancing the coolant output stability of the device. The design of the liquid storage cavity takes into account multiple factors such as the flight time of the aircraft, changes in cooling load and coolant replenishment intervals. By optimizing the geometric structure and material selection, it can achieve a wide range of adaptation to thermal requirements under different working conditions.

[0013] The suction layer and the vaporization zone work together during the working process to form a capillary force-vapor pressure dual-drive coolant active pressurization and transport mechanism. The former is responsible for maintaining a stable coolant supply and achieving quantitative and precise transport in high-temperature areas, while the latter provides additional power when the coolant transport is insufficient, compensating for the insufficient capillary drive response, and overcoming the additional mass burden problem brought by the coolant pump transport.

[0014] The axial holes of the axial steam outlet channel are located at each axial position; there is one axial hole in the center, and the remaining axial holes form a number of ring-shaped hole circles around the axis of the head cone to ensure rapid steam drainage and multi-channel coverage of the liquid supply path; each hole circle consists of a row of equidistant axial holes, and the number of holes in the first circle is expressed as D / 6 d 1 The integer part of the other rings of channels is expressed as D / 3.5 d 1 The integer part of the channel ring; the horizontal spacing in the radial direction is 2.5 d 1 , arranged in a continuous circular array, forming a D / 2.5 d 1 - 1 axial channel ring, where D is the maximum diameter of the cone section, d 1 is the diameter of the axial hole.

[0015] The radial holes of the radial steam outlet channel are arranged in a circular array at every radial position; the radial holes in the circular array are equally spaced, and the spacing between the radial holes is the circumference of the cross section π d x and the number of arrays n The ratio of d x When the axial distance from the center of the radial channel to the bottom of the suction layer is x When the radial channel center is located at the position of the head cone radial section circle diameter, the array number n Take the circumference of the cross section π d x With 2.5 times the radial aperture d 2 The integer part of the ratio of the arrays; the spacing between the arrays increases with the increase of the number of arrays, take n / 3 d 2 The integer part of .

[0016] The adaptive thermal protection device adopts active and passive composite thermal protection, wherein the thermal insulation layer is located at the outermost layer of the device, mainly undertakes the function of reducing high heat flow, and is constructed by low thermal conductivity porous ceramic material, effectively blocking the instantaneous impact of external shock wave heat flow on the internal structure, reducing the introduction speed of the heat load peak, and extending the heat transfer time window; the suction layer is arranged on the inner side of the thermal insulation layer, serving as an active cooling channel, and its internal capillary network forms a stable gas-liquid interface after the coolant enters and vaporizes, stimulating the capillary drive mechanism, thereby stably and continuously guiding the liquid coolant to the heated surface area; the two work together to form a composite thermal protection system of "external resistance and internal introduction", the former relies on passive physical properties to achieve heat flow shielding and slow release, and the latter achieves heat extraction and local temperature suppression through microscale transport. This composite mechanism still maintains good temperature control stability and dynamic response capabilities under high heat flux density and sudden heat load conditions, thereby improving the thermal protection level of the entire machine.

[0017] While ensuring structural strength, the thermal insulation layer utilizes a porous material. Leveraging the high-temperature stability and permeability of the porous ceramic material, it enables rapid discharge of the vapor-phase coolant and controlled gas-liquid separation. This exhaust channel structure also provides a slow-release heat transfer function, allowing heat to diffuse evenly and decompose gradually before reaching the extraction layer, creating favorable conditions for subsequent effective heat absorption and vaporization of the coolant.

[0018] The pumping layer is made of metal foam, ceramic sintered body, and porous high-temperature alloy sheet materials with high structural strength, precise porosity control, and moderate thermal conductivity. By adjusting structural parameters and matching material properties, this layer achieves a coordinated optimization of coolant absorption capacity, capillary pressure, and heat transfer efficiency, further enhancing the device's cooling capabilities.

[0019] The working fluid in the vaporization zone is made of a material with a low boiling point, high latent heat of phase change, and good chemical stability. This material can quickly vaporize under external heat flow conditions and generate stable steam pressure, triggering the expansion sleeve to respond and forming a secondary transport capability that drives the coolant flow under short-term internal high pressure.

[0020] The reservoir is filled with water, a coolant that vaporizes promptly in the heated area, effectively absorbing heat and maintaining thermal equilibrium within the device. After completing its local cooling task, the coolant exits the device in gaseous form through the exhaust channels of the suction layer and the thermal insulation layer, preventing condensation backflow from disrupting capillary flow stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below.

[0022] Figure 1 This is a schematic diagram of the heat flow on the nose cone of a hypersonic vehicle; Figure 2is a cross-sectional view of an adaptive thermal protection device; Figure 3 yes Figure 2 AA cross-section of Figure 4 is a schematic diagram of the suction layer; Figure 5 yes Figure 4 sectional view of Figure 6 is a schematic diagram of the axial perforation of the suction layer; Figure 7 is a schematic diagram of radial perforation of the suction layer; Figure 8 This is a schematic diagram of the working principle of the adaptive thermal protection device, where a is before heating and b is after heating; Figure 9 It is a schematic diagram of the working principle of the vaporization zone; Explanation of symbols: 101 - hypersonic incoming flow; 201 - thermal insulation layer; 202 - suction layer; 203 - vaporization zone; 204 - liquid storage chamber; 205 - expansion chamber; 206 - expansion sleeve; 501 - coolant; 502 - axial steam outlet channel; 503 - radial steam outlet channel; 901 - liquid saturated working medium; 902 - gaseous working medium. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0024] Figure 1 The diagram shows the heat flux distribution in the nose cone area of ​​the aircraft under hypersonic flight conditions. The darker the color, the higher the heat flux density, which represents the extreme heat load environment faced by the windward side of the aircraft under the action of high Mach number flow.

[0025] Figure 2 、 Figure 3 The cross-sectional view of the structure of the adaptive thermal protection device of the present invention is shown. The device includes a heat insulation layer 201, a suction layer 202, a vaporization area 203, a liquid storage chamber 204 and an expansion chamber 205.

[0026] Thermal insulation layer 201, located on the exterior surface of the vehicle's forebody, provides initial blocking and sustained heat release from external shock waves. Made of a porous ceramic composite material with low thermal conductivity and high-temperature stability, its structural design provides a certain degree of gas permeability, serving as a channel for coolant vapor discharge, forming a flow path for gas-liquid separation and steam exhaust guidance.

[0027] The pumping layer 202, located inside the insulation layer 201, is made of metal foam, microporous ceramics, or porous sintered high-temperature alloys. It forms a dense, gradient, three-dimensional porous network structure within the layer. This layer possesses significant capillary absorption capacity. In high-heat-flux environments, it forms a stable capillary force-driven mechanism through the evaporation interface. This allows for continuous adsorption and transport of liquid coolant to high-temperature areas without relying on any external pumps, achieving a self-driven coolant replenishment process.

[0028] Liquid reservoir 204 is a liquid coolant storage structure, enclosed by the inner wall of the suction layer 202, the inner wall of the expansion chamber 205, and the expansion sleeve 206. This structure provides both sealing and deformation resistance. The coolant is preferably water, which participates in cooling in both gas and liquid phases during different stages of the aircraft's operation. After vaporization, it is discharged to the outside through the insulation layer 201 to prevent internal overpressure and condensation interference.

[0029] The vaporization zone 203 is located within the expansion chamber 205, near the outer wall. Enclosed by a high-temperature, breathable metal material, it is filled with a high-temperature refrigerant, such as water or an electronic fluoride liquid. Novec™ 649 can be used as the electronic fluoride liquid. The high-temperature refrigerant must exhibit high thermal sensitivity and a high latent heat of phase change. Upon heating, it rapidly vaporizes, releasing a significant amount of vapor pressure. This vapor then permeates the permeable walls of the vaporization zone 203 and enters the expansion chamber 205.

[0030] The expansion chamber 205 acts as a pressure buffer and transfer device. It contains an expansion sleeve 206, which is made of a highly elastic polymer or a multi-layer composite elastomer. When high-pressure steam is generated in the vaporization zone 203 and transferred to the expansion chamber 205, the expansion sleeve 206 deforms under pressure and applies a uniform inward squeezing force to the liquid storage chamber 204, pushing the coolant toward the suction layer 202.

[0031] Figure 4 、 Figure 5The schematic diagram of the structure of the suction layer 202 of the present invention is shown. The suction layer 202 is a functional material layer with a porous structure. The interior of the suction layer is provided with a penetrating axial steam outlet channel 502 and a radial steam outlet channel 503, forming a highly interconnected three-dimensional capillary network structure. This structure significantly enhances the capillary drive effect while ensuring rapid steam drainage, thereby achieving efficient and continuous suction of the liquid coolant. The axial steam outlet channel 502 is arranged in a direction consistent with the main direction of the heat flow, and is used to quickly drain the steam formed by evaporation and reduce the air resistance effect; while the radial steam outlet channel 503 extends perpendicular to the heat flow direction, and cooperates with the axial channel to construct a complete steam discharge path, thereby improving the stability and response speed of the cooling process. This multi-channel collaborative structure not only provides excellent liquid suction performance, but also maintains the structural integrity and functional continuity of the suction layer under the action of high heat flux. The suction layer 202 can actively and continuously draw out the liquid coolant from the adjacent liquid storage chamber 204 through its significant capillary absorption capacity, effectively improving the coolant transportation efficiency in high heat flux density areas and ensuring the reliable operation of the cooling process under extreme heat loads.

[0032] Figure 6 This diagram illustrates the axially distributed porous structure of the pumping layer 202 of the present invention. For ease of illustration, the view is vertically downward from the cone's apex, and the radial steam extraction channels 503 are hidden. This design fully considers the axial symmetry of the nose cone's shape and the radial gradient of the heat load distribution to achieve efficient deep-depth coolant transport.

[0033] The axial channel of the axial steam outlet channel 502 has an axial channel in the center at each axial position, and the remaining axial channels form a number of annular channel rings around the axis of the head cone to ensure rapid steam drainage and multi-channel coverage of the liquid supply path; the aperture of each axial channel is d 1 , the maximum diameter of the head cone section is D Each axial hole circle consists of a row of equidistant axial holes. The number of holes in the first circle is expressed as D / 6 d 1 The integer part of the other rings of channels is expressed as D / 3.5 d 1 The center distance between the axial holes is 2.5 d 1 ; Arranged in a continuous circular array, a total of D / 2.5 d 1 - 1 hole ring in the axial direction.

[0034] The radial holes of the radial steam outlet channel are arranged in a circular array at every radial position; the radial holes in the circular array are equally spaced, and the distance between the radial holes is the circumference of the cross section π d x and the number of arrays n The ratio of d x When the axial distance from the center of the radial channel to the bottom of the suction layer is x When the radial channel center is located at the position of the head cone radial section circle diameter, the array number n Take the circumference of the cross section π d x With 2.5 times the radial aperture d 2 The integer part of the ratio of the arrays; the spacing between the arrays increases with the increase of the number of arrays, take n / 3 d 2 The integer part of .

[0035] Figure 7 The porous structure layout of the suction layer 202 in the present invention along the radial direction is shown. For ease of display, the nose cone is unfolded and the axial steam outlet channel 502 is hidden. The design of the radial steam outlet channel 503 combines the surface characteristics of the nose cone along the radial direction with the local heat flux density distribution law to construct a porous channel network that is adaptive to the heat load distribution. The radial channels on the radial steam outlet channel are arranged in a circular array; the radial channels in the circular array are equidistantly distributed, and the radial channel spacing is the cross-sectional circumference π d x and the number of arrays n The ratio of d x When the axial distance from the center of the radial channel to the bottom of the suction layer is x When the radial channel center is located at the position of the head cone radial section circle diameter, the array number n Take the circumference of the cross section π d x With 2.5 times the radial aperture d 2 The integer part of the ratio of the arrays; the spacing between the arrays increases with the increase of the number of arrays, take n / 3 d 2 This design not only improves the coupling ability between the pore network and the local heat flux intensity, but also enhances the overall controllability, local cooling efficiency and adaptability of the cooling structure, showing good engineering adaptability and functional stability under complex heat flux distribution conditions.

[0036] In one embodiment, the axial channel aperture d1 and radial channel diameter d 2 same.

[0037] Figure 8 、 Figure 9 A schematic diagram illustrates the operating principle of the adaptive thermal protection device of the present invention. This device addresses the thermal protection requirements of hypersonic vehicles in extreme thermal environments by integrating a multifunctional, coordinated system that combines heat flux release, coolant drive, and local self-regulation capabilities. During hypersonic flight, the leading edge and windward surfaces of the vehicle experience intense aerodynamic heating. The extreme external heat flux is initially intercepted and attenuated by the outermost insulation layer 201, which, composed of a low-thermal-conductivity material, reduces the heat flux transmitted to the inner layers. The remaining heat is then gradually transferred to the internal pumping layer 202. The pumping layer is a functional layer with a porous structure. Its internal capillary network, under thermal stimulation, stimulates capillary driving forces, guiding the passive migration of coolant along the porous channels from the liquid reservoir 204 to the heated area, achieving passive and precise coolant delivery. Simultaneously, the saturated liquid working medium 901 in the vaporization zone 203 near the heated area rapidly absorbs heat and transforms into a gaseous working medium 902. This phase transition significantly removes local heat, forming a highly efficient vaporization cooling mechanism. The resulting gaseous working fluid then enters the expansion chamber 205 located within the device, rapidly expanding within the confined space, generating pressure and driving the expansion sleeve 206 to undergo reversible deformation. The deformation of the expansion sleeve 206 squeezes the connected liquid storage chamber 204, allowing the liquid saturated working fluid 901 to be forcibly transported to the pumping layer 202 without the need for an external pump. This process forms a dynamic synergy between the coolant adsorption mechanism dominated by capillary force and the liquid supply drive mechanism assisted by vapor pressure, significantly improving the coolant supply efficiency and response speed in high heat flux areas. Through this mechanism, the present invention achieves a series of continuous processes, including coolant adsorption, vaporization, vapor expansion, and liquid supply drive, without relying on external energy or active control, to autonomously complete coolant adsorption, vaporization, vapor expansion, and liquid supply drive, thereby constructing a self-driven cooling system with high responsiveness, high stability, and self-regulation capabilities. The device can automatically adjust the liquid supply rate and cooling intensity according to the local heat flux intensity during flight, effectively ensuring the thermal stability of key parts of the aircraft and significantly improving the safety and reliability of hypersonic flight missions.

[0038] Example 1 To verify the feasibility of the adaptive thermal protection device provided by the present invention, the following is a simple estimate of whether the flow rate provided by the capillary force-pressure dual drive is greater than the required cooling water flow rate. Assuming that the thermal protection device is applied to the nose cone area of ​​a hypersonic aircraft in an airborne environment, the flight Mach number M 6, heating surface area A 1 m 2 , the external overall average heat flux density reduced by the insulation layer q0.5 MW / m 2 The suction layer is the radius of each channel. r 0.02 mm thick L 10 mm, axial and radial porosity ε Both are 20%, and the permeability is approximately εr 2 / 8, equivalent cross-sectional area of ​​the flow channel A f 0.2 m 2 , wetting angle The volume of coolant in the liquid storage chamber is 60°. V 1.5m 3 , the acceleration due to gravity is taken as 9.8 m / s². The free flow static pressure at the porosity head is is 2kPa, the specific heat ratio of air is The coolant and the saturated liquid working medium in the vaporization zone are both water.

[0039] For a normal shock wave, the headwind pressure at the front end of the nose cone Free flow and tranquility There are the following relationships:

[0040] because M >>1, the above formula can be simplified to:

[0041] The calculated headwind pressure at the front end of the nose cone is 84 kPa. The suction layer is connected to the atmosphere, so the pressure at the gas-liquid interface is also approximately 84 kPa. The saturation temperature is 94.5℃, and the surface tension of saturated water is is 0.06 N / m, latent heat of vaporization About 2.24×10 6 J / kg, dynamic viscosity μ 0.315×10 -3 Pa·s, density ρ 963.1 kg / m 3 .

[0042] In the equilibrium state, the pressure difference on both sides of the expansion sleeve The pressure difference on both sides of the suction layer , capillary pressure difference With gravity pressure Jointly determined, the calculation formula is:

[0043] After calculation, is 11.5 kPa. At this time, when the expansion chamber pressure is 95.5 kPa, the saturated vapor pressure of water is about 97.5℃. The coolant flow rate is 804 kg / h, so 1.5 m 3 The coolant water can maintain cooling for approximately 1.8 hours. In this embodiment, the extreme heat flow outside the extraction layer flows into the water, causing it to heat up. Once it reaches 94.5°C, it begins to vaporize. Simultaneously, the water in the vaporization zone increases in temperature and pressure, squeezing the liquid storage chamber. When the water temperature reaches 97.5°C, the refrigerant water mass flow rate stabilizes. Thereafter, the water in the vaporization zone continues to vaporize, maintaining the expansion chamber pressure. The water in the liquid storage chamber continues to vaporize, cooling the surface for approximately 1.8 hours.

Claims

1. An adaptive thermal protection device, characterized in that: include: A heat-insulating layer is provided on the outermost side; the heat-insulating layer is a porous ceramic structure; An expansion chamber connected to the bottom of the thermal insulation layer, with an expansion sleeve whose volume changes under pressure provided on the upper surface of the bottom of the expansion chamber; the expansion chamber is used to reduce the external high heat flow; A vaporization zone is provided inside the expansion chamber; the outer wall of the vaporization zone is made of a breathable material and the interior is filled with a liquid saturated working medium; A suction layer, the suction layer being located inside the thermal insulation layer, the suction layer being a porous network structure that generates capillary force at the air-liquid interface of the suction layer under a high heat flow environment; A liquid storage chamber, the liquid storage chamber is formed by the inner wall surface of the suction layer, the inner wall surface of the expansion chamber and the expansion sleeve; the liquid storage chamber is filled with a coolant; the coolant is transported to the thermal insulation layer through the porous network structure; when heated, the liquid saturated working medium in the expansion chamber vaporizes, enters the expansion chamber through the outer wall of the breathable material to provide pressure for the expansion sleeve, and is used to compress the cooling chamber, thereby realizing an adaptive cooling mechanism in which the greater the heat flow, the greater the pressure, and the greater the coolant flow rate, so as to respond to the pressure change of the expansion chamber and thereby achieve stable output of the coolant.

2. The adaptive thermal protection device according to claim 1, characterized in that: A penetrating axial steam outlet channel and a radial steam outlet channel are provided on the suction layer, and the axial steam outlet channel and the radial steam outlet channel constitute the porous network structure; the axial steam outlet channel is arranged in a direction consistent with the main direction of the heat flow, and is used to quickly outlet the steam formed by evaporation, thereby reducing the air resistance effect; the radial steam outlet channel extends in a direction perpendicular to the heat flow direction, and cooperates with the axial steam outlet channel to construct a complete steam discharge path, thereby improving the stability and response speed of the cooling process.

3. The adaptive thermal protection device according to claim 2, characterized in that: The axial holes of the axial steam outlet channel are located at each axial position; there is one axial hole in the center, and the remaining axial holes form a number of ring-shaped hole circles around the axis of the head cone to ensure rapid steam drainage and multi-channel coverage of the liquid supply path; each hole circle consists of a row of equidistant axial holes, and the number of holes in the first circle is expressed as D / 6 d 1 The integer part of the other rings of channels is expressed as D / 3.5 d 1 The integer part of ; The horizontal spacing of the channel ring in the radial direction is 2.5 d 1 , arranged in a continuous circular array, forming a D / 2.5 d 1 - 1 axial channel ring, where D is the maximum diameter of the cone section, d 1 is the diameter of the axial hole.

4. The adaptive thermal protection device according to claim 2, characterized in that: The radial holes of the radial steam outlet channel are arranged in a circular array at each radial position; the radial holes in the circular array are equidistantly distributed, and the distance between the radial holes is the circumference of the cross section π d x and the number of arrays n The ratio of d x When the axial distance from the center of the radial channel to the bottom of the suction layer is x When the radial channel center is located at the position of the head cone radial section circle diameter, the array number n Take the circumference of the cross section π d x With 2.5 times the radial aperture d 2 The integer part of the ratio of the arrays; the spacing between the arrays increases with the increase of the number of arrays, take n / 3 d 2 The integer part of .

5. The adaptive thermal protection device according to claim 1, characterized in that: The expansion sleeve is an elastically deformable material with high elastic recovery performance. When the saturated working medium in the vaporization area vaporizes, the steam enters the expansion chamber through the air-permeable wall to generate pressure. The expansion sleeve is deformed under pressure, thereby compressing the liquid storage chamber.

6. The adaptive thermal protection device according to claim 1, characterized in that: The heat insulation layer is made of porous ceramic material with high temperature stability.

7. The adaptive thermal protection device according to claim 1, characterized in that: The suction layer is made of metal foam, ceramic sintered body or high temperature resistant alloy porous material.

8. The adaptive thermal protection device according to claim 1, characterized in that: The liquid saturated working medium filled in the vaporization zone is made of a material with low boiling point, high latent heat, chemical inertness and thermal stability.

9. The adaptive thermal protection device according to claim 8, characterized in that: The liquid saturated working medium filled in the vaporization area is water or electronic fluoride liquid.

10. The adaptive thermal protection device according to claim 1, characterized in that: The coolant filled in the liquid storage cavity is water.

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