In-plane deformable thermal protection structure

Abstract

The present invention provides an in-plane deformable thermal protection structure, comprising a thermal protection surface layer, a thermal insulation core layer and a load-bearing layer that are sequentially stacked and connected; the thermal protection surface layer is provided with a plurality of first densified regions having a first preset shape, and the load-bearing layer is provided with a plurality of second densified regions having a second preset shape. The present invention realizes the integration of heat protection, heat insulation and load-bearing through the design of a multi-layer gradient thermal protection structure consisting of a thermal protection surface layer, a thermal insulation core layer and a load-bearing layer. Among them, the first densified region and the second densified region have been densified and have high strength and density, thereby improving the surface aerodynamic scour resistance of the thermal protection structure. The present invention has in-plane deformability, can achieve thermal matching with the fuselage structure, and can also be used directly as a thermal protection skin for hypersonic aircraft, meeting the requirements for aircraft reusability.

Description

Technical Field

[0001] The present invention relates to the field of thermal protection technology, and more particularly to an in-plane deformable thermal protection structure. Background Art

[0002] With the rapid development of aerospace technology, reusable hypersonic aircraft have become an important development direction in the world's aerospace field. During flight, due to the effect of aerodynamic loads, the surface temperature of the aircraft rises sharply. A high-performance thermal protection system must be used to protect the aircraft and maintain the temperature of the fuselage structure within the permitted range to ensure flight safety. Thermal protection technology has become one of the key technologies for reusable hypersonic aircraft. Among them, the fuselage (including wing skin) thermal protection structure accounts for the largest proportion of the total thermal protection area of ​​the aircraft. It mainly needs to withstand the thermal loads and aerodynamic loads on the wings and fuselage surfaces during hypersonic flight. It needs to have efficient thermal insulation performance under high temperature conditions, low structural weight, and reusability under comprehensive load conditions. It has become the focus and difficulty of thermal protection for hypersonic aircraft.

[0003] Currently, hypersonic equipment, such as near-space vehicles, space shuttles, and spaceplanes, all utilize rigid thermal tile systems as large-area thermal protection for fuselages and wings. These systems consist of an external coating, thermal tiles, strain isolation pads, and room-temperature-curing silicone. However, these systems suffer from poor insulation toughness and low high-temperature bond strength in the bonding area. Under combined thermal and mechanical loads, they are susceptible to thermal mismatch, leading to cracking and detachment of the insulation layer, resulting in the loss of the overall thermal protection function and rendering the structure unreusable. Furthermore, they are not subject to deformation, significantly reducing their structural stability. This is particularly true during takeoff and landing, where they are prone to vibration and detachment. Furthermore, the thermal expansion coefficients of the tiles differ significantly from those of the aircraft's main material, creating a significant temperature difference during reentry. This requires adequate gaps between the tiles, as these gaps can easily create thermal short-circuits, compromising the overall thermal protection effectiveness. This severely limits their application in reusable hypersonic aircraft.

[0004] Existing integrated heat-insulating / load-bearing structures fall into two main categories. One is a multilayer structure based on a combination of heat-insulating, heat-insulating, and load-bearing layers, achieved through interlayer bonding and integrated molding. However, these structures exhibit significant interface matching issues and are prone to interlayer cracking due to mismatched interlayer deformation in high-temperature environments, preventing in-plane deformation and stress release. The other is an integrated structure based on an insulation layer embedded in a lattice-structured load-bearing layer. By optimizing the lattice structure configuration and insulation material selection, the load-bearing performance and thermal protection capabilities of the integrated structure are enhanced. This type of structure has relatively high overall stiffness, and the thermal short-circuiting effect between the lattice structure members limits the optimization of the structure's thermal insulation performance. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is that the existing thermal protection structure cannot simultaneously meet the requirements of bearing aerodynamic loads, heat insulation and load-bearing, and is difficult to deform and easily produces thermal mismatch with the fuselage in a high-temperature environment.

[0007] (2) Technical solution

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] Provided is an in-plane deformable thermal protection structure for connection to an aircraft fuselage to provide a thermal protection function, comprising a thermal protection surface layer, a thermal insulation core layer and a bearing layer that are sequentially stacked and connected; the thermal protection surface layer is provided with a plurality of first densified regions having a first preset shape at intervals, and the bearing layer is provided with a plurality of second densified regions having a second preset shape at intervals.

[0010] Preferably, the material of the thermal insulation core layer is a nanoporous thermal insulation material, and the nanoporous thermal insulation material includes at least one of fiber thermal insulation felt, organic / inorganic foam, aerogel, and porous ceramics.

[0011] Preferably, the heat-proof surface layer and the first densified region are formed by selectively densifying a first densified material on the surface of the thermal insulation core layer; wherein the first densified material includes at least one of carbon, silicon carbide, silicon oxide, aluminum oxide, zirconium oxide, and resin.

[0012] Preferably, the bearing layer and the second densified region are formed by selective densification of a second densified material on the surface of the thermal insulation core layer; wherein the second densified material includes at least one of aluminum, titanium, resin, carbon, silicon carbide, silicon oxide, aluminum oxide, and zirconium oxide.

[0013] Preferably, the thickness of the heat-proof surface layer is 0.1-5 mm, the thickness of the heat-insulating core layer is 0.5 mm-50 mm, and the thickness of the bearing layer is 0.1-10 mm.

[0014] Preferably, there is a first non-densified region between every two adjacent first densified regions, and the width of the first non-densified region is 0.1 mm to 3 mm.

[0015] Preferably, there is a second non-densified region between every two adjacent second densified regions, and the width of the second non-densified region is 0.1 mm to 3 mm.

[0016] Preferably, the cross-sectional shape of the first densified region is rectangular, circular or hexagonal.

[0017] Preferably, the cross-sectional shape of the second densified region is rectangular, circular or hexagonal.

[0018] Preferably, the plurality of first densified regions and the plurality of second densified regions are arranged in a one-to-one correspondence along the thickness direction of the in-plane deformable heat protection structure.

[0019] (3) Beneficial effects

[0020] The above technical solution of the present invention has at least the following advantages:

[0021] 1. The first densified region and the second densified region are formed by densification treatment and have high strength and density, thereby improving the anti-surface aerodynamic scour performance of the thermal protection structure.

[0022] 2. Since the multiple first densified regions are spaced apart, that is, there is a gap between two adjacent first densified regions, the structural strength at the gap is relatively small compared to the first densified regions, so the gap can be deformed and bent to achieve the in-plane deformability of the heat-resistant surface layer. Similarly, since the multiple second densified regions are spaced apart, that is, there is a gap between two adjacent second densified regions, the structural strength at the gap is relatively small compared to the second densified regions, so the gap can be deformed and bent to achieve the in-plane deformability of the load-bearing layer. Through the in-plane deformability of the present invention, thermal matching with the fuselage structure can be achieved, and it can also be directly used as a thermal protection skin for hypersonic aircraft to meet the requirements of aircraft reusability. At the same time, the high-strength first densified region and the second densified region ensure the anti-surface aerodynamic scour performance of the entire thermal protection structure.

[0023] 3. The heat shield surface layer is made of high-temperature-resistant materials, providing heat protection and preventing the insulation core from direct contact with the high-temperature environment. The insulation core layer is made of materials with excellent thermal insulation properties, which can block heat transfer and provide insulation. The load-bearing layer is made of materials with strong mechanical properties and serves as a load-bearing structure to meet the aircraft's load-bearing requirements, enhancing the thermal protection structure's load-bearing capacity. The thermal protection structure's resistance to surface aerodynamic erosion is provided by the first densified region, while its deformation capacity is provided by the non-densified region of the heat shield surface layer. The shape and distribution of the densified region can be designed according to aerodynamic loads and deformation requirements, allowing the heat shield surface layer to deform in-plane through expansion and contraction of the non-densified region. The load-bearing capacity of the thermal protection structure is provided by the load-bearing layer, which can also be designed with a second densified region of varying shapes and sizes to increase the overall structure's deformation capacity. The thermal insulation layer is made of nanoporous insulation material, providing thermal insulation for the entire thermal protection structure. That is, the present invention can realize the integration of heat protection, heat insulation and load bearing through the multi-layer gradient thermal protection structure design composed of a heat-proof surface layer, a heat-insulating core layer and a load-bearing layer, and at the same time has the ability of in-plane deformability and can achieve thermal matching with the body structure. The technical solution of this application has great strategic significance in airspace competition. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the structure of the in-plane deformable thermal protection structure provided by an embodiment of the present invention.

[0026] Figure 2 It is a schematic structural diagram of the heat-proof surface layer provided in an embodiment of the present invention.

[0027] Figure 3 It is a structural schematic diagram of the bearing layer provided by an embodiment of the present invention.

[0028] The reference numerals in the figures are:

[0029] 1. Heat-proof surface layer; 2. Heat-insulating core layer; 3. Bearing layer; 11. First rectangular densification area; 12. First square densification area; 13. First circular densification area; 14. First hexagonal densification area; 15. First non-densification area; 31. Second rectangular densification area; 32. Second square densification area; 33. Second circular densification area; 34. Second hexagonal densification area; 35. Second non-densification area. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] It should be noted that when an element is referred to as being “fixed to” or “disposed on” another element, it may be directly located on the other element or indirectly located on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0032] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating relative importance or the number of technical features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. The following is a more detailed description of the specific implementation of the present invention in conjunction with specific embodiments:

[0034] like Figure 1 、 Figure 2 and Figure 3As shown, an embodiment of the present invention provides an in-plane deformable thermal protection structure for connection to an aircraft fuselage to provide a thermal protection function, comprising a thermal protection surface layer 1, a thermal insulation core layer 2, and a bearing layer 3 that are sequentially stacked and connected; the thermal protection surface layer 1 is provided with a plurality of first densified regions having a first preset shape at intervals, and the bearing layer is provided with a plurality of second densified regions having a second preset shape at intervals. The bearing performance of the in-plane deformable thermal protection structure is provided by the bearing layer 3, and the bearing layer 3 can also be designed with second densified regions of different shapes and distributions to increase the deformation capacity of the overall structure. The thermal insulation core layer 2 is made of nanoporous thermal insulation material to provide thermal insulation performance for the in-plane deformable thermal protection structure. Specifically, the first preset shape and the second preset shape may be the same or different, and may be determined according to actual application requirements. The first densified region and the second densified region have been densified (the densification treatment is based on the thermal insulation core layer 2, and the first densified material is immersed in a specific solvent on one side of the thermal insulation core layer 2, and a specific process (such as sintering) is performed to increase the density of the region to form the thermal protection surface layer 1 and the first densified region, and the second densified material is immersed in a specific solvent on the other side of the thermal insulation core layer 2, and a specific process (such as sintering) is performed to increase the density of the region to form the second densified region and the bearing layer 3), and have high strength and density, thereby improving the surface aerodynamic erosion resistance of the thermal protection structure. The shape and distribution of the first densified region can be designed according to the different aerodynamic loads and deformation requirements of the thermal protection surface layer 1, and the shape and distribution of the second densified region can be designed according to the different aerodynamic loads and deformation requirements of the bearing layer 3. Because the multiple first densified regions are spaced apart, i.e., gaps are provided between adjacent first densified regions, the structural strength of the gaps is relatively low compared to the first densified regions. Thus, the gaps can deform and bend, thereby achieving the in-plane deformability of the heat-shielding surface layer 1. Similarly, because the multiple second densified regions are spaced apart, i.e., gaps are provided between adjacent second densified regions, the structural strength of the gaps is relatively low compared to the second densified regions. Thus, the gaps can deform and bend, thereby achieving the in-plane deformability of the load-bearing layer 3. Therefore, when the present invention is installed on a fuselage, even if the thermal expansion coefficient of the fuselage material differs from that of the material of the in-plane deformable heat-shielding structure provided by the present invention, and the deformations of the two materials are different, the in-plane deformable heat-shielding structure provided by the present invention can match the deformation of the fuselage through its own in-plane deformability, ensuring that the deformations of the two are consistent, thereby preventing the heat-shielding structure from falling off the fuselage and enabling the heat-shielding structure to be reused for multiple flight missions. The present invention can also be directly used as a thermal protection skin for hypersonic aircraft, meeting the requirements for aircraft reusability.

[0035] In one embodiment, the insulating core layer 2 is made of a nanoporous insulating material, including at least one of fiber insulation felt, organic / inorganic foam, aerogel, and porous ceramics. The insulating core layer 2 is flexible, allowing the side of the heat-resistant surface layer 1 adjacent to the insulating core layer 2 to deform. The insulating core layer 2 serves to block heat transfer, preventing heat generated by high temperatures from directly affecting the fuselage structure.

[0036] In one embodiment, the heat-resistant surface layer 1 and the first densified region are integrally formed from a first densified material. The heat-resistant surface layer and the first densified region are formed by selectively densifying the first densified material on the surface of the thermal insulation core layer. The first densified material comprises at least one of carbon, silicon carbide, silicon oxide, aluminum oxide, zirconium oxide, and resin. These materials have excellent high-temperature resistance, preventing damage to the thermal insulation core layer 2 from direct contact with high-temperature environments and thus protecting the thermal insulation core layer 2.

[0037] In one embodiment, the load-bearing layer 3 and the second densified region are integrally formed from a second densified material. The load-bearing layer and the second densified region are formed by selectively densifying the second densified material on the surface of the thermal insulation core layer. The second densified material comprises at least one of aluminum, titanium, resin, carbon, silicon carbide, silicon oxide, aluminum oxide, and zirconium oxide. These materials have excellent mechanical properties and can be used as load-bearing structures to meet the load-bearing requirements of aircraft.

[0038] In one embodiment, the thickness of the heat-proof surface layer 1 is 0.1-5 mm, the thickness of the heat-insulating core layer 2 is 0.5-50 mm, and the thickness of the bearing layer 3 is 0.1-10 mm.

[0039] In one embodiment, a first non-densified region 15 (i.e., the gap described above) is located between each adjacent first densified region. The width of the first non-densified region 15 is 0.1 mm to 3 mm. Compared to the first densified region, the first non-densified region has a relatively lower structural strength and can deform and bend, thereby achieving in-plane deformability of the heat-resistant surface layer 1.

[0040] In one embodiment, a second non-densified region 35 (i.e., the gap described above) is located between each adjacent second densified region. The width of the second non-densified region 35 is 0.1 mm to 3 mm. Compared to the second densified region, the second non-densified region has a relatively lower structural strength and can deform and bend, thereby achieving in-plane deformability of the support layer 3.

[0041] In one embodiment, the cross-sectional shape of the first densified region is rectangular, circular or hexagonal. Specifically, the first densified region can be designed into various geometric shapes according to design requirements, such as Figure 2 As shown in (a), the first densified region can be a first rectangular densified region 11 in the shape of a long rectangle, as shown in FIG. Figure 2 As shown in (b), the first densified region can be a square-shaped first square densified region 12, as shown in FIG. Figure 2 As shown in (c), the first densified region may be a circular first circular densified region 13, such as Figure 2 As shown in (d), the first densified region may be a hexagonal first hexagonal densified region 14 .

[0042] In one embodiment, the cross-sectional shape of the second densified region is rectangular, circular or hexagonal. Specifically, the second densified region can be designed into various geometric shapes according to design requirements, such as Figure 3 As shown in (a), the second densified region can be a second rectangular densified region 31 in the shape of a long rectangle, as shown in FIG. Figure 3 As shown in (b), the second densified region may be a square-shaped second square densified region 32, as shown in FIG. Figure 3 As shown in (c), the second densified region may be a circular second circular densified region 33, such as Figure 3 As shown in (d), the second densified region may be a hexagonal second densified region 34 .

[0043] In one embodiment, the plurality of first densified regions and the plurality of second densified regions are arranged in a one-to-one correspondence along the thickness direction of the in-plane deformable heat protection structure.

[0044] The following are specific embodiments provided by the present invention:

[0045] Example 1

[0046] The thermal insulation core layer 2 selected in this embodiment is mullite fiber reinforced silica aerogel material with a specification of 200mm×200mm×20mm; the heat-proof surface layer 1 is selectively densified by alumina to form a first densified area, the first densified area is rectangular, with a specification of 200mm×19mm×0.5mm, uniformly distributed in the surface, and the non-densified area is 200mm×1mm×0.5mm; the bearing layer 3 is selectively densified by polyimide resin to form a second densified area, the second densified area is rectangular, with a specification of 200mm×19mm×0.5mm, uniformly distributed in the surface and corresponding to the first densified area, and the non-densified area is 200mm×1mm×0.5mm.

[0047] The basic properties of the obtained samples are shown in the following table:

[0048]

[0049] Example 2

[0050] The thermal insulation core layer 2 selected in this embodiment is alumina fiber felt with a specification of 300mm×300mm×30mm; the heat-proof surface layer 1 is selectively densified with silicon carbide to form a first densified area, the first densified area is rectangular with a specification of 29mm×29mm×1mm, uniformly distributed in the surface, and the non-densified area is 300mm×1mm×1mm, distributed in strips; the bearing layer 3 is selectively densified with silicon oxide to form a second densified area, the second densified area is rectangular with a specification of 29mm×29mm×1mm, uniformly distributed in the surface and corresponding to the first densified area, and the non-densified area is 300mm×1mm×1mm, distributed in strips.

[0051] The basic properties of the obtained samples are shown in the following table:

[0052]

[0053] Example 3

[0054] The thermal insulation core layer 2 used in this embodiment is a polyimide foam with dimensions of 400 mm × 400 mm × 10 mm. The heat-resistant surface layer 1 is selectively densified using polyimide resin to form a first densified region. This first densified region is circular, measures φ20 mm × 2 mm, and is evenly distributed within the surface. The maximum width of the non-densified region is 0.2 mm. The load-bearing layer 3 is selectively densified using polyimide resin to form a second densified region. This second densified region is circular, measures φ20 mm × 2 mm, and is evenly distributed within the surface, corresponding to the first densified region. The maximum width of the non-densified region is 0.2 mm.

[0055] The basic properties of the obtained samples are shown in the following table:

[0056]

[0057] It can be seen that the in-plane deformable heat protection structure prepared in the embodiment of the present invention has good temperature resistance, airflow erosion resistance, thermal insulation performance and in-plane deformability.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An in-plane deformable thermal protection structure for connecting to an aircraft fuselage to provide thermal protection, characterized in that: It includes a heat-proof surface layer, a heat-insulating core layer and a bearing layer which are stacked and connected in sequence; the heat-proof surface layer is provided with a plurality of first densified regions with a first preset shape, and the bearing layer is provided with a plurality of second densified regions with a second preset shape; wherein, the first densified region and the second densified region have been subjected to densification treatment, and the densification treatment is based on the heat-insulating core layer, and the density of the region is increased by immersing the first densified material in a specific solvent on one side surface of the heat-insulating core layer and sintering the material to form the heat-proof surface layer and the first densified region, and the density of the region is increased by immersing the second densified material in a specific solvent on the other side surface of the heat-insulating core layer and sintering the material to form the second densified region and the bearing layer.

2. The in-plane deformable heat protection structure according to claim 1, characterized in that: The material of the thermal insulation core layer is a nanoporous thermal insulation material, and the nanoporous thermal insulation material includes at least one of fiber thermal insulation felt, organic / inorganic foam, aerogel, and porous ceramics.

3. The in-plane deformable heat protection structure according to claim 1, characterized in that: The heat-proof surface layer and the first densified region are formed by selectively densifying a first densified material on the surface of the thermal insulation core layer; wherein the first densified material includes at least one of carbon, silicon carbide, silicon oxide, aluminum oxide, zirconium oxide, and resin.

4. The in-plane deformable heat protection structure according to claim 1, wherein: The bearing layer and the second densified region are formed by selective densification of a second densified material on the surface of the thermal insulation core layer; wherein the second densified material includes at least one of aluminum, titanium, resin, carbon, silicon carbide, silicon oxide, aluminum oxide, and zirconium oxide.

5. The in-plane deformable heat protection structure according to claim 1, wherein: The thickness of the heat-proof surface layer is 0.1-5 mm, the thickness of the heat-insulating core layer is 0.5-50 mm, and the thickness of the bearing layer is 0.1-10 mm.

6. The in-plane deformable heat protection structure according to claim 1, characterized in that: There is a first non-densified region between every two adjacent first densified regions, and the width of the first non-densified region is 0.1 mm to 3 mm.

7. The in-plane deformable heat protection structure according to claim 1, wherein: There is a second non-densified region between every two adjacent second densified regions, and the width of the second non-densified region is 0.1 mm to 3 mm.

8. The in-plane deformable heat protection structure according to claim 1, wherein: The cross-sectional shape of the first densified region is rectangular, circular or hexagonal.

9. The in-plane deformable heat protection structure according to claim 1, wherein: The cross-section of the second densified region is rectangular, circular or hexagonal.

10. The in-plane deformable heat protection structure according to claim 1, wherein: The plurality of first densified regions and the plurality of second densified regions are arranged in a one-to-one correspondence along the thickness direction of the in-plane deformable heat protection structure.

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