Metal honeycomb-double-layer active cooling composite thermal protection structure and manufacturing method

Abstract

The application relates to a metal honeycomb-double-layer active cooling composite heat protection structure and a manufacturing method, wherein the manufacturing method of the metal honeycomb-double-layer active cooling composite heat protection structure comprises the following steps: an outer skin, an inner skin, a honeycomb core, a plurality of hot surface cooling flow channels and a plurality of cold surface cooling flow channels are respectively prepared by using metal materials, and brazing filler metals are fixed; a plurality of parallel grooves are processed at two ends of the honeycomb core, the hot surface cooling flow channels are placed in the grooves at one end, and the cold surface cooling flow channels are placed in the grooves at the other end; the outer skin and the inner skin are assembled with the honeycomb core, the assembled test piece is placed into a vacuum brazing furnace for vacuum brazing, and the metal honeycomb-double-layer active cooling composite heat protection structure is prepared. The application can significantly reduce the weight and volume of the heat protection structure and improve the selectivity of the heat protection structure material.

Description

Technical Field

[0001] This application relates to the field of aerospace manufacturing technology, and in particular to a metal honeycomb-double-layer active cooling composite thermal protection structure and its manufacturing method. Background Technology

[0002] Metal honeycomb sandwich structures, as a novel lightweight and high-temperature resistant structure, possess excellent properties such as light weight, high specific strength and stiffness, high temperature resistance, and corrosion resistance, and are widely used in the aerospace field to achieve thermal protection. However, for hypersonic vehicles with long flight times, thermal protection cannot be achieved solely by relying on the honeycomb structure and its core heat sink. Thermal protection structures that combine honeycomb load-bearing structures with active cooling structures offer advantages such as lightweight and integrated load-bearing and thermal insulation, making them significant for hypersonic long-range vehicles. This type of structure uses the honeycomb structure as the primary load-bearing and heat-resistant component, and the thermal protection performance of the honeycomb structure depends on the heat resistance of the material itself. The honeycomb layers and active cooling layers are composited through welding, bonding, or mechanical connections, resulting in significant weight and volume, and complex manufacturing processes. Therefore, further reducing the weight and volume of metal honeycomb-active cooling composite thermal protection structures and improving the selectivity of thermal protection materials have become urgent problems to be solved.

[0003] Therefore, the inventors provide a metal honeycomb-double-layer active cooling composite thermal protection structure and its manufacturing method. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] This application provides a metal honeycomb-double-layer active cooling composite thermal protection structure and manufacturing method. The technical problem to be solved is: how to further reduce the weight and volume of the metal honeycomb-active cooling composite thermal protection structure and improve the selectivity of thermal protection structure materials.

[0006] (2) Technical solution

[0007] In a first aspect, this application provides a method for manufacturing a metal honeycomb-double-layer active cooling composite thermal protection structure, comprising:

[0008] The outer skin, inner skin, honeycomb core, multiple hot-side cooling channels, and multiple cold-side cooling channels are made of metal materials, and the brazing filler metal is fixed in place.

[0009] Multiple parallel grooves are machined at both ends of the honeycomb core. The hot side cooling channel is placed in the groove at one end, and the cold side cooling channel is placed in the groove at the other end.

[0010] The outer and inner skins are assembled with the honeycomb core, and the assembled specimen is placed in a vacuum brazing furnace for vacuum brazing to obtain a metal honeycomb-double-layer active cooling composite thermal protection structure.

[0011] Furthermore, the metallic material is one of titanium alloy, stainless steel, or high-temperature alloy.

[0012] Furthermore, the thickness of the outer skin and the inner skin is 0.5 to 1 mm.

[0013] Furthermore, the end face of the honeycomb core is a regular hexagon with an inscribed circle diameter of 9.6–50 mm; the wall thickness of the honeycomb core is 0.05 mm–0.1 mm, and the height is 15–40 mm.

[0014] Furthermore, the hot-side cooling channel is a long straight channel with an arc-shaped cross-section, a height not greater than 1 / 5 of the total height of the composite thermal protection structure, a width of 20-50 mm, and air as the cooling medium; the interval between each hot-side cooling channel is not less than the width of the hot-side cooling channel.

[0015] Furthermore, the cold-side cooling channel is a long straight channel with a rectangular cross-section. Its height is no more than 1 / 3 of the total height of the composite thermal protection structure, and its width is 10-30mm. The cooling medium is fuel oil. The interval between each cold-side cooling channel is no less than the width of the cold-side cooling channel.

[0016] Furthermore, the manufacturing method further includes:

[0017] Multiple support bar assemblies are made of metal material, and each support bar assembly includes two wedge-shaped support bars and one rectangular support bar;

[0018] Before assembling the outer and inner skins with the honeycomb core, support strip assemblies are placed in the hot and cold cooling channels to ensure that the support strip assemblies fit completely into the cooling channels.

[0019] Furthermore, the vacuum level inside the vacuum brazing furnace during brazing is less than 1×10⁻⁶. -2 Pa, the brazing temperature is 30℃~100℃ above the melting point of the brazing filler metal, the holding time is 15min~120min, the amount of brazing filler metal added is 30μm~90μm, and the brazing gap is not greater than 0.05mm.

[0020] Furthermore, the manufacturing method further includes:

[0021] After the brazing process is completed, the test piece is cooled to below 150°C in the furnace and then removed from the furnace. After the test piece is cooled to room temperature, the support strip assembly is removed, and the finished metal honeycomb-double-layer active cooling composite thermal protection structure is obtained.

[0022] Secondly, this application provides a metal honeycomb-double-layer active cooling composite thermal protection structure, which is manufactured based on the manufacturing method described above.

[0023] (3) Beneficial effects

[0024] The above-mentioned technical solution of this application has the following advantages:

[0025] The metal honeycomb-double-layer active cooling composite thermal protection structure and manufacturing method provided in this application integrate the double-layer active cooling structure into the honeycomb layer to form an integrated load-bearing and thermal insulation structure, which can significantly reduce the weight and volume of the thermal protection structure. The double-layer cooling channels dissipate heat from both the hot and cold surfaces of the thermal protection structure, which can significantly improve the temperature uniformity of the composite structure and also increase the selectivity of structural materials. At the same time, from the perspective of welding tooling design, a split support component is designed, which can effectively reduce structural deformation during brazing and effectively reduce post-weld processing time, thereby improving production efficiency. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 A perspective view of the metal honeycomb-double-layer active cooling composite thermal protection structure provided in this application;

[0028] Figure 2 A side view of the metal honeycomb-double-layer active cooling composite thermal protection structure provided in this application;

[0029] Figure 3 A schematic diagram of the assembled metal honeycomb-double-layer active cooling composite thermal protection structure specimen provided in this application;

[0030] Figure 4 A schematic diagram of the hot-surface support strip assembly provided in this application;

[0031] Figure 5 A schematic diagram of the cold-surface support strip assembly provided in this application;

[0032] Figure 6 An assembly diagram of the hot-surface support strip assembly provided in this application;

[0033] Figure 7 This is an assembly diagram of the cold-surface support strip assembly provided in this application.

[0034] Reference numerals: 1. Outer skin; 2. Hot-side cooling channel; 3. Honeycomb core; 4. Cold-side cooling channel; 5. Inner skin; 6. Hot-side channel support strip assembly; 7. Cold-side channel support strip assembly; 61. Curved wedge support strip; 62. Curved wedge support strip; 63. Rectangular support strip; 71. Wedge support strip; 72. Wedge support strip; 73. Rectangular support strip. Detailed Implementation

[0035] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0036] It should be understood that, when used in this application specification and appended claims, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, in the description of this application specification and appended claims, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0038] Hypersonic vehicles experience severe aerodynamic heating during operation, especially during atmospheric reentry. The primary function of thermal protection structures is to control the heat flow entering the vehicle, maintaining the underlying structure within permissible temperature ranges. The development and optimized design of thermal protection structures are crucial to the success of advanced hypersonic vehicles.

[0039] Metal honeycomb sandwich structures, as a novel lightweight and high-temperature resistant structure, possess excellent properties such as light weight, high specific strength and stiffness, high temperature resistance, and corrosion resistance, and are widely used in the aerospace field. Metal honeycomb sandwich structures are manufactured using vacuum brazing, with the cavities within the core in a near-vacuum state. Their thermal conductivity is much lower than that of metallic materials, achieving thermal protection. However, for hypersonic vehicles with long flight times, the temperature of the external skin continuously increases during flight. If the internal structure lacks a corresponding cooling mechanism, external heat will continuously conduct to the internal structure, potentially causing it to exceed its operating temperature. Therefore, for hypersonic vehicles with long flight times, thermal protection cannot be achieved solely by relying on the honeycomb structure and the heat sink in the sandwich portion.

[0040] Chinese invention patent CN109264030B discloses a convection cooling active thermal protection structure, comprising a surface high-temperature alloy honeycomb sandwich structure, a middle titanium alloy convection cooling panel, and an inner titanium alloy honeycomb sandwich structure. The surface and middle layers are bonded together with a high-temperature resistant metal adhesive, and the middle and inner layers are connected using adhesives or fasteners. The convection cooling active thermal protection structure uses fuel as a coolant, which reduces the surface temperature of the inner layer during the convection cooling process while simultaneously preheating the fuel.

[0041] The thermal protection structure that combines a honeycomb load-bearing structure with an active cooling structure has many advantages, such as being lightweight and integrating load-bearing and thermal insulation. The development of a load-bearing and thermal insulation integrated thermal protection structure with an active cooling mechanism is of great significance for hypersonic long-range aircraft.

[0042] Thermal protection structures that combine honeycomb structures with active cooling insulation layers primarily employ a two-layer composite structure. The honeycomb layer, placed on the hot side, serves a load-bearing function, while the active cooling layer, placed on the cold side, provides insulation. This type of structure uses the honeycomb structure as its main load-bearing and heat-resistant component; the thermal protection performance of the honeycomb structure depends on the inherent heat resistance of the material itself. The honeycomb layer and active cooling layer are composited through welding, bonding, or mechanical connections, resulting in significant weight and volume, and complex manufacturing processes. Therefore, further reducing the weight and volume of metal honeycomb-active cooling composite thermal protection structures and improving the selectivity of thermal protection materials are urgent problems to be solved.

[0043] This application aims to provide a metal honeycomb-double-layer active cooling composite thermal protection structure and its manufacturing method, in order to solve the problems of large weight and volume, poor material selectivity, and complex processes in existing composite thermal protection structures. Furthermore, based on the structural characteristics, welding process, and operational properties of the metal honeycomb-double-layer active cooling composite thermal protection structure, a one-time integral brazing manufacturing process has been developed.

[0044] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0045] This embodiment provides a method for manufacturing a metal honeycomb-double-layer active cooling composite thermal protection structure, including:

[0046] The outer skin, inner skin, honeycomb core, multiple hot-side cooling channels, and multiple cold-side cooling channels are made of metal materials, and the brazing filler metal is fixed in place.

[0047] Multiple parallel grooves are machined at both ends of the honeycomb core. The hot side cooling channel is placed in the groove at one end, and the cold side cooling channel is placed in the groove at the other end.

[0048] The outer and inner skins are assembled with the honeycomb core, and the assembled specimen is placed in a vacuum brazing furnace for vacuum brazing to obtain a metal honeycomb-double-layer active cooling composite thermal protection structure.

[0049] In applications, metal honeycomb-double-layer active cooling composite thermal protection structures, such as Figure 1 and Figure 2 As shown, the fuselage includes an outer skin 1, a hot-side cooling channel 2, a honeycomb core 3, a cold-side cooling channel 4, and an inner skin 5. The outer skin 1 forms the aerodynamic shape of the fuselage, bearing the thermal load and transferring heat inwards. The cooling medium of the hot-side cooling channel 2 is air, which absorbs the heat transferred from the hot end. The honeycomb core 3 is lightweight and high-strength, and after being connected to the skin by brazing, it can serve as the main load-bearing structure. The cooling medium of the cold-side cooling channel 4 is fuel, which can absorb the heat transferred by the honeycomb core 3, further reducing the internal temperature of the fuselage while also preheating the fuel.

[0050] In some embodiments, the metallic material is one of titanium alloy, stainless steel, or high-temperature alloy.

[0051] In some embodiments, the thickness of the outer skin and the inner skin is 0.5 to 1 mm.

[0052] In some embodiments, the end face of the honeycomb core is a regular hexagon with an inscribed circle diameter of 9.6–50 mm; the wall thickness of the honeycomb core is 0.05 mm–0.1 mm, and the height is 15–40 mm.

[0053] In some embodiments, the hot-side cooling channel is a long straight channel with an arc-shaped cross-section, a height not greater than 1 / 5 of the total height of the composite thermal protection structure, a width of 20-50 mm, and air as the cooling medium; the interval between each hot-side cooling channel is not less than the width of the hot-side cooling channel.

[0054] In some embodiments, the cold-side cooling channel is a long straight channel with a rectangular cross-section, a height not greater than 1 / 3 of the total height of the composite thermal protection structure, a width of 10-30 mm, and fuel oil as the cooling medium; the interval between each cold-side cooling channel is not less than the width of the cold-side cooling channel.

[0055] In application, to improve heat exchange efficiency, the hot-side cooling channel 2 adopts an arc-shaped channel. The arc-shaped channel has good formability, a large heat exchange area with the outer skin 1, and high heat exchange efficiency. The cold-side cooling channel 4 adopts a rectangular channel, which can extend the heat transfer path from the outer skin 1 to the inner skin 5, allowing the cooling medium to fully absorb the heat transferred from the hot end. By embedding the double-layer cooling channels into the honeycomb layer, all or most of the heat is carried away by the working fluid or coolant, significantly improving the selectivity of thermal protection materials, effectively reducing the volume of the thermal protection structure, saving fuselage space, and improving thermal protection efficiency.

[0056] In some embodiments, the manufacturing method further includes:

[0057] Multiple support bar assemblies are made of metal material, and each support bar assembly includes two wedge-shaped support bars and one rectangular support bar;

[0058] Before assembling the outer and inner skins with the honeycomb core, support strip assemblies are placed in the hot and cold cooling channels to ensure that the support strip assemblies fit completely into the cooling channels.

[0059] In some embodiments, the vacuum level in the vacuum brazing furnace during brazing is less than 1 × 10⁻⁶. -2 Pa, the brazing temperature is 30℃~100℃ above the melting point of the brazing filler metal, the holding time is 15min~120min, the amount of brazing filler metal added is 30μm~90μm, and the brazing gap is not greater than 0.05mm.

[0060] In some embodiments, the manufacturing method further includes:

[0061] After the brazing process is completed, the test piece is cooled to below 150°C in the furnace and then removed from the furnace. After the test piece is cooled to room temperature, the support strip assembly is removed, and the finished metal honeycomb-double-layer active cooling composite thermal protection structure is obtained.

[0062] In the application, titanium alloy can be used to make the outer skin 1 and inner skin 5, with a thickness of 0.5 mm. Titanium alloy foil is rolled into semi-regular hexagonal corrugated strips, which are then spot-welded together to form a honeycomb core 3 with regular hexagonal end faces. The honeycomb core is then machined to create grooves for cooling channels. The corrugated strip can have a height of 23 mm, a wall thickness of 0.1 mm, and an inscribed circle diameter of 12.8 mm for the regular hexagonal end faces. Multiple arc-shaped hot-side cooling channels 2 and rectangular cold-side cooling channels 4 are fabricated using titanium alloy through hot forming. The hot-side cooling channels can have a height of 4 mm, a width of 30 mm, and a wall thickness of 0.3 mm; the cold-side cooling channels can have a height of 8 mm, a width of 15 mm, and a wall thickness of 0.3 mm.

[0063] Multiple sets of hot-side flow channel support strip assemblies 6 and cold-side flow channel support strip assemblies 7 are manufactured from titanium alloy blocks using machining methods, such as... Figure 3 As shown. The hot-face flow channel support strip assembly includes curved wedge-shaped support strips 61 and 62 and a rectangular support strip 63, as... Figure 4 As shown; the cold runner support strip assembly includes wedge-shaped support strips 71 and 72 and a rectangular support strip 73, as... Figure 5 As shown. The surface oxide layer of the brazing surfaces of the prepared outer skin 1, hot-side cooling channel 2, honeycomb core 3, cold-side cooling channel 4, and inner skin 5 is removed by mechanical cleaning. Then, titanium-based amorphous brazing foil is fixed to the brazing surfaces of the outer skin, cooling channel, and inner skin by resistance spot welding. The thickness of the brazing foil is 30-50 μm.

[0064] The hot-side cooling channel 2 and cold-side cooling channel 4, with the brazing filler metal fixed, are placed in the grooves of the honeycomb core, and their relative positions to the honeycomb core are fixed by spot welding. Then, the hot-side support strip assemblies 6 are inserted one by one into the gaps of each hot-side cooling channel in the order of 61, 62, and 63. Figure 6 As shown; cold surface support strip assemblies 7 are inserted one by one into the gaps of each cold surface cooling channel in the order of 71, 72, 73, as shown. Figure 7 As shown. Finally, the outer skin 1 and inner skin 5 are assembled with the honeycomb core to obtain a metal honeycomb-double-layer active cooling composite thermal protection structure specimen, as shown. Figure 3 As shown.

[0065] The assembled test piece is placed in a vacuum brazing furnace for vacuum brazing. During brazing, the vacuum level inside the furnace should be less than 1 × 10⁻⁶. -2Pa, heated from room temperature to 940–980℃ at a rate of 2–5℃ / min, and held at that temperature for 15–120 min. After the brazing process, the specimen was cooled in the furnace to below 150℃ and then removed. After the specimen cooled to room temperature, the support strip assemblies in the hot-side cooling channels were removed one by one in the order of 63, 62, 61, and the support strip assemblies in the cold-side cooling channels were removed one by one in the order of 73, 72, 71. After removing the support strips, the finished metal honeycomb-double-layer active cooling composite thermal protection structure was obtained, such as... Figure 1 As shown.

[0066] The metal honeycomb-double-layer active cooling composite thermal protection structure prepared using the above method exhibits good structural integrity, light weight, strong high-temperature thermal stability, and can be reused multiple times. By designing wedge-shaped support strip components, the brazing gap and surface accuracy during the brazing process can be guaranteed. Furthermore, compared to integral support strips, individual components of the split support strips are easier to remove after welding, effectively reducing post-weld processing time and improving production efficiency.

[0067] This embodiment also provides a metal honeycomb-double-layer active cooling composite thermal protection structure, which is manufactured based on the manufacturing method described above.

[0068] In applications, the metal honeycomb-double-layer active cooling composite thermal protection structure includes an outer skin, hot-side cooling channels, a honeycomb core, cold-side cooling channels, and an inner skin. The outer skin, hot-side cooling channels, honeycomb core, cold-side cooling channels, and inner skin are connected using vacuum brazing. The outer skin, intermediate skin, and inner skin are made of titanium alloy plate, stainless steel plate, or high-temperature alloy plate, with a thickness of 0.5–1 mm. The honeycomb core has a regular hexagonal end face; the honeycomb core material is made of titanium alloy foil, stainless steel foil, or high-temperature alloy foil, and is the same as the skin material; the honeycomb core has a wall thickness of 0.05 mm–0.1 mm, a height of 15–40 mm, and the inscribed circle diameter of the regular hexagonal end face is 9.6–50 mm.

[0069] The hot-side cooling channels are long, straight channels with an arc-shaped cross-section; there are multiple cooling channels arranged in parallel; the height of each cooling channel is no greater than 1 / 5 of the total height of the composite thermal protection structure; the width of each cooling channel is 20–50 mm; the parallel spacing between cooling channels is no less than the width of the cooling channel. The cold-side cooling channels are long, straight channels with a rectangular cross-section; there are multiple cooling channels arranged in parallel; the height of each cooling channel is no greater than 1 / 3 of the total height of the composite thermal protection structure; the width of each cooling channel is 10–30 mm; the parallel spacing between cooling channels is no less than the width of the cooling channel; the cooling medium for the cold-side cooling channels is fuel oil. The hot-side and cold-side cooling channels are staggered on the inner surfaces of the outer and inner skins, respectively.

[0070] Metal sheets can be made into outer and inner skins, then the outer and inner skins are cleaned and dried for later use; metal foil is rolled or stamped into semi-hexagonal corrugated strips, and multiple corrugated strips are spliced ​​together by spot welding to form a honeycomb core with regular hexagonal honeycomb end faces, then the honeycomb core is machined to leave grooves for placing cooling channels, and after processing, it is cleaned and dried for later use; metal sheets are thermoformed into multiple hot-side cooling channels with arc-shaped cross sections and cold-side cooling channels with rectangular cross sections, then the cooling channels are cleaned and dried for later use.

[0071] Metal blocks are machined into hot-side and cold-side flow channel support strip assemblies. The support strips are then cleaned and dried for later use. The support strips are made of one of the following materials: titanium alloy, stainless steel, or high-temperature alloy, and are the same as the materials used for the resulting skin and cooling channels. Specifically, each support strip assembly includes two wedge-shaped support strips and one rectangular support strip. After being placed in the flow channel, the support strip assembly should fit completely against the cooling channel.

[0072] The surface oxide layer of the brazing surfaces of the prepared outer skin, hot-side cooling channels, honeycomb core, cold-side cooling channels, and inner skin is removed using mechanical or chemical cleaning methods. Then, amorphous brazing foil is fixed to the brazing surfaces using resistance spot welding. Specifically, the brazing foil is one of titanium-based, nickel-based, or cobalt-based brazing alloys, and corresponds to the materials of the prepared skin and core.

[0073] The hot and cold cooling channels, with the brazing filler metal fixed in place, are placed in the corresponding grooves of the honeycomb core. Their relative positions to the honeycomb core are then fixed using spot welding. Next, the fabricated support strip assemblies are placed into the cooling channels. Finally, the inner and outer skins are fixed to the honeycomb core to obtain the assembled metal honeycomb-double-layer active cooling composite thermal protection structure specimen. Specifically, the surface of the support strip assembly should be coated with a flow-blocking agent, and after the support strips are installed, the surface of the support strip assembly should be flush with the upper surface of the cooling channels.

[0074] The assembled test piece is placed in a vacuum brazing furnace for vacuum brazing. Specifically, the vacuum level inside the vacuum brazing furnace should be better than 1×10⁻⁶ during brazing. -2 For brazing, the temperature should be 30℃ to 100℃ above the melting point of the brazing filler metal, the holding time should be 15min to 120min, the filler metal addition amount should be 30μm to 90μm, and the brazing gap should not exceed 0.05mm. After the brazing process is completed, the specimen is cooled in the furnace to below 150℃, then the furnace is opened and the specimen is removed. After the specimen has cooled to room temperature, the support strip assemblies in the cooling channels are removed one by one to obtain the finished product.

[0075] The metal honeycomb-double-layer active cooling composite thermal protection structure and manufacturing method provided in this application combine a double-layer cooling channel with a honeycomb core, which can effectively reduce the weight and volume of the thermal protection structure and save fuselage space. The arc-shaped hot-side cooling channel can increase the heat exchange contact area between the cooling medium and the hot-end environment, thereby improving heat exchange efficiency; at the same time, the cooling medium carries away most of the heat from the hot-end environment, which can significantly improve the selectivity of thermal protection materials and improve the heat protection efficiency of the thermal protection structure. The rectangular cold-side cooling channel can extend the heat transfer path, allowing the cooling medium to fully absorb the heat transferred from the hot end, effectively reducing the cold-end temperature; at the same time, using fuel as the cooling medium, the fuel is preheated while reducing the cold-side temperature, saving energy.

[0076] The composite thermal protection structure is fabricated using integral brazing, which, compared to commonly used adhesive bonding and mechanical joining methods, results in a welded joint with better integrity, lighter weight, stronger high-temperature thermal stability, and can be reused multiple times. By designing a split wedge-shaped support strip assembly, the brazing gap and surface accuracy during the brazing process can be guaranteed. Furthermore, compared to integral support strips, individual components of the split support strip are easier to remove after welding, effectively reducing post-weld processing time and improving production efficiency.

[0077] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0078] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for manufacturing a metal honeycomb-double-layer active cooling composite thermal protection structure, characterized in that, include: The outer skin, inner skin, honeycomb core, multiple hot-side cooling channels, and multiple cold-side cooling channels are made of metal materials, and the brazing filler metal is fixed in place. Multiple parallel grooves are machined at both ends of the honeycomb core. The hot side cooling channel is placed in the groove at one end, and the cold side cooling channel is placed in the groove at the other end. The outer skin and inner skin are assembled with the honeycomb core, and the assembled specimen is placed in a vacuum brazing furnace for vacuum brazing to obtain a metal honeycomb-double-layer active cooling composite thermal protection structure. The hot-side cooling channel is a long, straight channel with an arc-shaped cross-section. Its height is no more than 1 / 5 of the total height of the composite thermal protection structure, and its width is 20-50 mm. The cooling medium is air. The interval between each hot-side cooling channel is no less than the width of the hot-side cooling channel.

2. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 1, characterized in that, The metal material is one of titanium alloy, stainless steel, or high-temperature alloy.

3. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 1, characterized in that, The thickness of the outer skin and the inner skin is 0.5~1mm.

4. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 1, characterized in that, The end face of the honeycomb core is a regular hexagon with an inscribed circle diameter of 9.6~50mm; the wall thickness of the honeycomb core is 0.05mm~0.1mm and the height is 15~40mm.

5. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 1, characterized in that, The cold-side cooling channel is a long, straight channel with a rectangular cross-section. Its height is no more than 1 / 3 of the total height of the composite thermal protection structure, and its width is 10-30mm. The cooling medium is fuel oil. The interval between each cold-side cooling channel is no less than the width of the cold-side cooling channel.

6. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 1, characterized in that, The manufacturing method further includes: Multiple support bar assemblies are made of metal material, and each support bar assembly includes two wedge-shaped support bars and one rectangular support bar; Before assembling the outer and inner skins with the honeycomb core, support strip assemblies are placed in the hot and cold cooling channels to ensure that the support strip assemblies fit completely into the cooling channels.

7. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 1, characterized in that, The vacuum level inside the vacuum brazing furnace during brazing is less than 1×10⁻⁶. -2 Pa, the brazing temperature is 30℃~100℃ above the melting point of the brazing filler metal, the holding time is 15min~120min, the amount of brazing filler metal added is 30μm~90μm, and the brazing gap is not greater than 0.05mm.

8. The manufacturing method of the metal honeycomb-double-layer active cooling composite thermal protection structure as described in claim 6, characterized in that, The manufacturing method further includes: After the brazing process is completed, the test piece is cooled to below 150°C in the furnace and then removed from the furnace. After the test piece is cooled to room temperature, the support strip assembly is removed, and the finished metal honeycomb-double-layer active cooling composite thermal protection structure is obtained.

9. A metal honeycomb-double-layer active cooling composite thermal protection structure, characterized in that, The metal honeycomb-double-layer active cooling composite thermal protection structure is manufactured based on the manufacturing method described in any one of claims 1 to 8.

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