A thermal protection structure for high-temperature and supersonic aircraft

Abstract

A thermal protection structure for high-temperature and supersonic aircraft belongs to the technical field of thermal protection for aircraft under high heat flux density, comprising a water absorbing layer and its leading edge region and two side regions, wherein the leading edge region comprises a first evaporative cooling porous medium layer, a cross-scale porous medium layer and a high-temperature resistant wall surface sequentially laid on the outside of the leading edge of the water absorbing layer; the two side regions comprise a second and a third evaporative cooling porous medium layer respectively laid on the outside of both sides of the water absorbing layer, and a coolant transport pipeline connected to the leading edge and the two side regions is provided on the inner side of the water absorbing layer; the capillary force of the micron-scale and nano-scale pores of the first evaporative cooling porous medium layer and the cross-scale porous medium layer is utilized to draw fluid to the high-temperature resistant wall surface, the millimeter-scale pores of the cross-scale porous medium layer provide a steam escape channel, the high-temperature resistant wall surface blocks the direct disturbance of the high-temperature mainstream on the fluid in the porous medium, and the steam outlets on both sides of the leading edge stagnation point discharge steam; the present invention has the advantages of not requiring an additional fluid supply power device, being resistant to high temperatures and having high cooling efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal protection of aircraft under high heat flux density, and in particular relates to a thermal protection structure for high-temperature and supersonic aircraft. Background Art

[0002] With the advancement of aerospace technology, aircraft speeds are constantly increasing. The extremely high speeds of hypersonic vehicles (Ma > 5) enable them to reach any location globally in a short period of time, which is of great significance in both defense and commercial fields. This has led to increasingly high temperatures and heat flux densities in key hot components of aerospace turbine engines, liquid rocket engines, and hypersonic vehicles, necessitating the use of efficient active cooling methods to thermally protect these high-temperature components. Compared to other thermal protection technologies such as regenerative cooling and film cooling, evaporative cooling offers higher cooling efficiency and has been widely studied and applied to thermal protection of high-heat-flux surfaces. While evaporative cooling can effectively prevent ablation of high-temperature components, localized oxidation and ablation can still occur at locations such as the leading edge of a wing or nose cone. The high-temperature, high-speed mainstream airflow at the leading edge is significantly higher than that at other areas. Stagnation near the leading edge results in increased pressure, making it difficult for the evaporative cooling fluid to escape from the leading edge, resulting in temperatures significantly higher than those in other areas. The large temperature gradient induces localized thermal stresses, reducing the reliability and service life of high-temperature components. Evaporative cooling can effectively protect most areas of the strut, but has a poor cooling effect on the leading edge.

[0003] Patent application publication number CN 119018358 A discloses a transpiration-cooled leading edge thermal protection structure coupled with reverse steam injection. By employing reverse steam injection at the leading edge, the structure achieves uniform and efficient cooling of both stagnation and non-stagnation areas under the protection of a dual air film. However, due to the high pressure in the stagnation area, the reverse steam injection system requires a large amount of energy, and the structure's internal pore distribution is random, limiting its thermal protection performance. Summary of the Invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a thermal protection structure for high-temperature and supersonic aircraft, by designing a double-layer porous structure of a first evaporative cooling porous medium layer and a cross-scale porous medium layer in the leading edge area, utilizing the capillary force of the tiny pores in the double-layer porous structure to draw the fluid to the high-temperature resistant wall surface, utilizing the millimeter-level pores of the cross-scale porous medium layer to provide an escape channel for the steam, and at the same time, the high-temperature resistant wall surface blocks the direct disturbance of the high-temperature mainstream on the fluid inside the porous medium, allowing the coolant to flow smoothly through the cross-scale porous medium layer to the inside of the high-temperature resistant wall surface, and the steam outlets located on both sides of the leading edge stagnation point to discharge the steam in time, thereby realizing efficient cooling of the high-temperature resistant wall surface; the present invention solves the problem of local ablation caused by the difficulty of the coolant flowing to the leading edge position in the existing evaporative cooling structure, and has the advantages of no need for an additional liquid supply power device, high temperature resistance and high cooling efficiency.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A thermal protection structure for high-temperature and supersonic aircraft includes a water-absorbing layer, wherein the water-absorbing layer includes a leading edge region and two side regions. The leading edge region includes a first evaporative cooling porous medium layer, a cross-scale porous medium layer, and a high-temperature resistant wall surface sequentially laid on the outside of the leading edge of the water-absorbing layer; the two side regions include a second evaporative cooling porous medium layer and a third evaporative cooling porous medium layer respectively laid on the outside of the two sides of the water-absorbing layer. A coolant transport pipeline is provided on the inner side of the water-absorbing layer, and the outlet end of the coolant transport pipeline is respectively connected to the leading edge region and the two side regions of the water-absorbing layer, and an inlet is provided at the inlet end of the coolant transport pipeline.

[0007] One end of the second evaporative cooling porous medium layer and the third evaporative cooling porous medium layer are respectively connected to the end close to the first evaporative cooling porous medium layer.

[0008] The water-absorbing layer is filled with hydrophilic fiber material.

[0009] A first steam outlet and a second steam outlet are provided on both sides of the high temperature resistant wall.

[0010] The cross-scale porous medium layer includes a skeleton, in which a plurality of millimeter-scale pores that are interconnected are arranged, and micrometer-scale pores and nanometer-scale pores are respectively arranged on the skeleton.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. To address the complex design and high energy consumption of evaporative cooling systems that rely on pumping coolant, the present invention utilizes a first evaporative cooling porous medium layer, a second evaporative cooling porous medium layer, a third evaporative cooling porous medium layer, and a cross-scale porous medium layer, respectively, disposed at the leading edge and both sides of the water absorption layer. These layers draw the cooling fluid to the high-temperature resistant wall surface at the leading edge through capillary action, eliminating the need for an additional fluid supply power device.

[0013] 2. In order to solve the problem that the high-speed mainstream at the leading edge directly disturbs the cooling fluid inside the porous medium, making it difficult for it to flow to the leading edge, the high-temperature resistant wall surface located in the leading edge area of ​​the present invention blocks the direct disturbance of the high-temperature mainstream on the fluid inside the porous medium, allowing the coolant to flow smoothly to the inside of the high-temperature resistant wall surface, thereby achieving efficient cooling of the high-temperature resistant wall surface located in the leading edge area.

[0014] 3. To address the problem of random distribution of porous structures, difficulty in controlling the pore structure, and limitation of the thermal protection performance of the porous structure, the present invention designs a double-layer porous structure of a first evaporative cooling porous medium layer and a cross-scale porous medium layer in the leading edge area, giving full play to the functions of pores of different scales, realizing autonomous control of the coolant flow, and facilitating steam escape.

[0015] 4. To address the problem of high pressure at the stagnation point, which makes it difficult for steam to escape and causes steam blockage and large temperature fluctuations, the present invention provides a first steam outlet and a second steam outlet on both sides of the leading edge area, avoiding the stagnation point with the highest pressure and facilitating steam escape.

[0016] In summary, the present invention designs a double-layer porous structure of a first evaporative cooling porous medium layer and a cross-scale porous medium layer, a high-temperature resistant wall surface, and a first steam outlet and a second steam outlet located on both sides of the leading edge area. There is no need to set up a pump supply device, which blocks the direct disturbance of the high-temperature mainstream on the fluid inside the porous medium, facilitates the timely escape of steam, and has the advantages of a simple liquid supply system, high temperature resistance and high cooling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the thermal protection structure of high-temperature and supersonic aircraft of the present invention.

[0018] Figure 2 Schematic diagram of the TPMS structure of the skeleton of the cross-scale porous medium layer of the present invention.

[0019] Figure 3 Schematic diagram of the nail column structure of the skeleton of the cross-scale porous medium layer of the present invention.

[0020] Figure 4 Schematic diagram of the SC-BCC lattice structure of the skeleton of the cross-scale porous medium layer of the present invention.

[0021] Figure 5Schematic diagram of the internal pore structure of the TPMS cross-scale porous media skeleton provided in an embodiment of the present invention.

[0022] Figure 6 Schematic diagram of the thermal overload area of ​​the high-temperature and supersonic aircraft of the present invention.

[0023] Figure 7 For the present invention Figure 1 Schematic diagram of the working principle of the high temperature and leading edge area A position of the supersonic aircraft thermal protection structure.

[0024] Figure 8 This is a scanning electron microscope image of the structure of the skeleton of the cross-scale porous medium layer of the present invention.

[0025] Among them, 1. inlet; 2. coolant transport pipeline; 3. water absorption layer; 41. first evaporative cooling porous medium layer; 42. second evaporative cooling porous medium layer; 43. third evaporative cooling porous medium layer; 5. cross-scale porous medium layer; 51. TPMS structure; 52. nail column structure; 53. SC-BCC lattice structure; 61. first steam exhaust port; 62. second steam exhaust port; 7. high temperature resistant wall; 8. skeleton; 81. millimeter-level pores; 82. micrometer-level pores; 83. nanometer-level pores. DETAILED DESCRIPTION

[0026] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0027] like Figure 1As shown, a thermal protection structure for high-temperature and supersonic aircraft includes an inlet 1 and a coolant transport pipeline 2, a water absorption layer 3, a first evaporative cooling porous medium layer 41, a second evaporative cooling porous medium layer 42, a third evaporative cooling porous medium layer 43, a cross-scale porous medium layer 5, a high-temperature resistant wall 7, a first steam outlet 61 and a second steam outlet 62; the coolant enters the coolant transport pipeline 2 from the inlet 1; the water absorption layer 3 is a hydrophilic fiber material, which draws the coolant in the coolant transport pipeline 2 to the water absorption layer 3 through a strong capillary force without any additional power device; the first evaporative cooling porous medium layer 41, the second evaporative cooling porous medium layer 42 and the third evaporative cooling porous medium layer 43 are connected by capillary force. The fine force draws the coolant in the water absorption layer 3 to its surface, and the coolant in the heated pores on the surface of the second evaporative cooling porous medium layer 42 and the third evaporative cooling porous medium layer 43 undergoes a gas-liquid phase change and escapes and forms a dense gas film on the surface. The coolant phase change latent heat and the gas film work together to achieve the cooling purpose; and a cross-scale porous medium layer 5 is set in the leading edge area. The cross-scale porous medium layer 5 includes a skeleton 8, and a number of millimeter-level pores 81 that are interconnected are set in the skeleton 8. The millimeter-level pores 81 are used to provide channels for steam to escape. Micrometer-level pores 82 and nanometer-level pores 83 are arranged on the skeleton 8. The micrometer-level pores 82 and nanometer-level pores 83 draw the coolant to the high-temperature resistant wall surface 7 through capillary force. The skeleton 8 of the cross-scale porous medium layer 5 can adopt: TPMS structure 51, and its structural schematic diagram is as follows Figure 2 As shown; nail column structure 52, its structural schematic diagram is as shown Figure 3 As shown; SC-BCC lattice structure 53, its structural schematic diagram is as shown Figure 4 The skeleton 8 of the cross-scale porous medium layer 5 takes the TPMS structure 51 as an example, and the schematic diagram of its internal pore structure is as shown in FIG. Figure 5 As shown. The skeleton 8 is provided with micron-scale pores 82 and nano-scale pores 83. The strong capillary force of the micron-scale pores 82 and nano-scale pores 83 draws the coolant from the first evaporative cooling porous medium layer 41 into the interior of the cross-scale porous medium layer 5. The cross-scale porous medium layer 5 contacts the high-temperature resistant wall surface 7. The high-temperature resistant wall surface 7 blocks the direct disturbance of the high-temperature mainstream on the fluid inside the porous medium, allowing the coolant to flow smoothly through the cross-scale porous medium layer 5 to the inner surface of the high-temperature resistant wall surface 7. The coolant absorbs heat and undergoes a gas-liquid phase transition. The generated steam flows from the cross-scale porous medium layer 5 to the first steam outlet 61 and the second steam outlet 62. The provision of the first steam outlet 61 and the second steam outlet 62 can avoid discharging steam at the stagnation point with the highest pressure, thus facilitating steam escape.

[0028] The diameter of the millimeter-scale pores 81 is greater than 1 mm, the diameter of the micrometer-scale pores 82 is 1-1000 μm, and the diameter of the nanometer-scale pores 83 is 1-1000 nm.

[0029] The skeleton 8 of the cross-scale porous medium layer 5 may adopt an SC-BCC lattice structure 53 , which has higher mechanical strength and higher specific surface area than traditional structures.

[0030] The skeleton 8 of the cross-scale porous medium layer 5 can adopt a nail column structure 52, which has a simple structure and convenient design. The cross-row arrangement can enhance fluid disturbance and strengthen the heat exchange process.

[0031] The skeleton 8 of the cross-scale porous medium layer 5 can adopt a TPMS structure 51. Its curved surface structure can be represented by an implicit function f(x, y, z) = 0. It has the characteristics of convenient modeling, high design freedom, large specific surface area, and low flow resistance. Several typical structures are as follows:

[0032]

[0033] Evaporative cooling can effectively prevent high-temperature components from being ablated, but localized oxidation and ablation still occur in the leading edge region (wing leading edge, nose cone leading edge). The aerodynamic heat flux density of the high-temperature, high-speed mainstream at the leading edge is much higher than that of other regions. After the mainstream stagnates near the leading edge, the pressure increases, making it difficult for the evaporatively cooled cooling fluid to flow out of the leading edge. The present invention designs a dual-layer porous structure consisting of a first evaporative cooling porous medium layer 41 and a cross-scale porous medium layer 5. On the one hand, the capillary force of the first evaporative cooling porous medium layer 41 and the cross-scale porous medium layer 5 draws the cooling fluid to the high-temperature resistant wall surface 7 in the leading edge region. On the other hand, the millimeter-scale pores 81 of the cross-scale porous medium layer 5 serve as channels for steam escape, thereby efficiently cooling the high-temperature resistant wall surface 7 in the leading edge region. This solves the problem of the high-speed mainstream in the leading edge region directly disturbing the cooling fluid inside the porous medium, making it difficult for it to flow to the leading edge.

[0034] The object of the present invention is to provide a thermal protection structure for high-temperature and supersonic aircraft to solve the problem of local ablation caused by the difficulty of coolant flowing to the leading edge position in the existing evaporative cooling structure.

[0035] This embodiment takes the thermal protection of supersonic aircraft as an example. Figure 6 As shown. Due to the extremely high flight speed, the leading edge of the wing and the leading edge of the nose cone are subjected to ultra-high heat loads, and the temperature gradient between the local leading edge and the surrounding area is large. This embodiment follows the technical solution of the present invention, selects the typical position of the wing as the implementation object, and designs a high-temperature and supersonic aircraft thermal protection structure, such as Figure 1As shown, it includes a coolant transport pipeline 2, a water absorption layer 3, a first evaporative cooling porous medium layer 41, a second evaporative cooling porous medium layer 42, a third evaporative cooling porous medium layer 43, a cross-scale porous medium layer 5, and a high-temperature resistant wall surface 7; the coolant enters the coolant transport pipeline 2 from the inlet 1; the water absorption layer 3 is a hydrophilic fiber material, which draws the coolant in the coolant transport pipeline 2 to the water absorption layer 3 through a strong capillary force without the need for any additional power device; the first evaporative cooling porous medium layer 41, the second evaporative cooling porous medium layer 42, and the third evaporative cooling porous medium layer 43 draw the coolant in the water absorption layer 3 to their surfaces through capillary force, the surfaces of the second evaporative cooling porous medium layer 42 and the third evaporative cooling porous medium layer 43 are heated, the coolant in the pores undergoes a gas-liquid phase change and escapes to form a dense gas film on the surface, the coolant phase change latent heat and the gas film work together to achieve the cooling purpose; and the working principle diagram of the leading edge area A of the thermal protection structure of high-temperature and supersonic aircraft of the present invention is shown as follows Figure 7 As shown, a cross-scale porous medium layer 5 is provided, which includes a skeleton 8 and a plurality of millimeter-scale pores 81 that are interconnected in the skeleton 8. The structure of the skeleton 8 is shown in a scanning electron microscope image. Figure 8 As shown, the porous structure is generally reticular, with spherical protrusions attached to the grid. The pore structure is disordered, with irregular pore sizes and shapes. Micron-scale pores 82 and nano-scale pores 83 are arranged on the skeleton 8. The strong capillary force of the micron-scale pores 82 and nano-scale pores 83 draws the coolant from the first evaporative cooling porous medium layer 41 into the interior of the cross-scale porous medium layer 5. The cross-scale porous medium layer 5 contacts the high-temperature resistant wall surface 7, which blocks the direct disturbance of the high-temperature mainstream on the fluid inside the porous medium. This allows the coolant to flow smoothly through the cross-scale porous medium 5 into the interior of the high-temperature resistant wall surface 7. The coolant absorbs heat and undergoes a gas-liquid phase transition. The generated steam flows through the millimeter-scale pores 81 in the cross-scale porous medium 5 to the first steam outlet 61 and the second steam outlet 62.

Claims

1. A thermal protection structure for high-temperature and supersonic aircraft, characterized in that: The invention comprises a water absorbing layer (3), wherein the water absorbing layer (3) comprises a leading edge region and two side regions, wherein the leading edge region comprises a first evaporative cooling porous medium layer (41), a cross-scale porous medium layer (5) and a high-temperature resistant wall surface (7) sequentially laid on the outer side of the leading edge of the water absorbing layer (3); the two side regions comprise a second evaporative cooling porous medium layer (42) and a third evaporative cooling porous medium layer (43) respectively laid on the outer sides of the water absorbing layer (3); a coolant transport pipe (2) is provided on the inner side of the water absorbing layer (3), the outlet end of the coolant transport pipe (2) is respectively connected to the leading edge region and the two side regions of the water absorbing layer (3), and the inlet end of the coolant transport pipe (2) is provided with an inlet (1).

2. A high-temperature and supersonic aircraft thermal protection structure according to claim 1, characterized in that: One end of the second evaporative cooling porous medium layer (42) and the third evaporative cooling porous medium layer (43) are respectively connected to the end of the first evaporative cooling porous medium layer (41).

3. The high-temperature and supersonic aircraft thermal protection structure according to claim 1, characterized in that: The water-absorbing layer (3) is filled with hydrophilic fiber material.

4. The high-temperature and supersonic aircraft thermal protection structure according to claim 1, characterized in that: A first steam outlet (61) and a second steam outlet (62) are provided on both sides of the high-temperature resistant wall surface (7).

5. The high-temperature and supersonic aircraft thermal protection structure according to claim 1, characterized in that: The cross-scale porous medium layer (5) includes a skeleton (8), wherein a plurality of millimeter-scale pores (81) that are interconnected are provided in the skeleton (8), and micrometer-scale pores (82) and nanometer-scale pores (83) are respectively arranged on the skeleton (8).

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