A wide temperature range heat dissipation front edge

Abstract

The application discloses a wide temperature range heat dissipation front edge, and belongs to the technical field of thermal protection of high-speed aircrafts. The structure comprises a metal shell, a dense-packed ball capillary, a reinforcing rib, a working medium, a dot matrix structure, a metal pipeline, a storage tank, porous ceramics, a pressure switch and a cooling fin. The metal shell has a front edge shape. The dense-packed ball capillary is arranged on the inner surface of the metal shell, and the working medium is uniformly adsorbed in the dense-packed ball capillary. The dot matrix structure and one end of the metal pipeline are connected with the metal shell, and the other end is connected with the storage tank. The porous ceramics and the pressure switch are respectively arranged in different metal pipelines, and the metal shell and the storage tank are isolated into two semi-sealed structures. The cooling fin is connected with the bottom of the storage tank. The application has a use temperature range of 600-2200 DEG C, can greatly reduce the thermal stress of the heat dissipation front edge, and improve the reliability and safety of the heat dissipation type thermal protection.

Description

Technical Field

[0001] This invention relates to a wide-temperature-range heat-resistant leading edge, belonging to the field of thermal protection technology for high-speed aircraft. Background Technology

[0002] The operating temperature at the leading edge of high-speed aircraft is getting increasingly higher, reaching or even exceeding the upper limit of the operating temperature of existing heat protection materials. Dissipative thermal protection is one feasible approach to solving this problem.

[0003] Common heat dissipation structures include nickel-based, niobium-based, molybdenum-based, and tantalum-based structures. Among these, nickel-based structures have an operating temperature range of 600–1100℃, niobium-based structures 900–1400℃, molybdenum-based structures 1000–1800℃, and tantalum-based structures 1300–2200℃. Due to their narrow operating temperature range, heat dissipation structures face severe thermal stress problems in heat protection applications, making them difficult to apply to leading-edge heat protection of transoceanic, highly maneuverable aircraft. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a wide-temperature-range heat-resistant leading edge that can extend the operating temperature range to 600-2200℃, significantly reducing the thermal stress of the leading edge and improving the reliability and safety of heat-resistant thermal protection.

[0005] The technical solution of this invention is:

[0006] A wide-temperature-range heat-insulating leading edge includes a metal shell, a densely packed spherical capillary structure, reinforcing ribs, a working medium, a lattice structure, metal pipelines, a storage tank, porous ceramics, a pressure switch, and cooling fins.

[0007] The metal shell has a leading edge shape and is connected to the storage tank through multiple metal pipes at the tail end face; there are three or more metal pipes, two of which are equipped with porous ceramics, one of which is equipped with a pressure switch, and the remaining metal pipes are equipped with either porous ceramics or pressure switches.

[0008] The densely packed spherical capillary structure is placed on the inner surface of the metal shell, and multiple working media are uniformly adsorbed in the densely packed spherical capillary structure.

[0009] The reinforcing ribs are installed inside the metal shell to improve the rigidity of the metal shell;

[0010] The dot matrix structure is disposed between the metal shell and the storage tank;

[0011] The cooling fins are connected to the bottom of the storage tank.

[0012] Furthermore, the metal shell, the densely packed spherical capillary structure, and the reinforcing ribs are integrated into a single structure, and are all made of tantalum-tungsten alloy.

[0013] Furthermore, the thickness of the densely packed spherical capillary structure is 0.8 mm to 2.0 mm, and the porosity is 25% to 60%.

[0014] Furthermore, the working medium occupies 8% to 15% of the volume of the metal shell. The working medium is a mixture of sodium metal, lithium metal, and lead-bismuth alloy, wherein sodium metal accounts for 25% to 35% of the volume of the working medium, lithium metal accounts for 25% to 35% of the volume of the working medium, and lead-bismuth alloy accounts for 30% to 50% of the volume of the working medium.

[0015] Furthermore, the thickness of the lattice structure is 20mm to 50mm, and the strength is 150MPa to 200MPa; the lattice structure is a diamond array, the side length of the unit cell is 10mm to 25mm, and the diameter of the connecting post is 1.2mm to 5mm.

[0016] Furthermore, the porous ceramic has a porosity of 50%–90% and a permeability of 1.3–5 × 10⁻⁶. –10 m 2 .

[0017] Furthermore, the pressure switch is placed on a separate metal pipeline. When the pressure difference between the metal housing and the storage tank is greater than 3 kPa, the pressure switch changes from open to closed, isolating the metal housing and the storage tank into two sealed structures.

[0018] Furthermore, the storage tank is made of niobium-tungsten alloy, and its volume is 3 to 10 times the volume of the working medium.

[0019] Furthermore, the cooling fins have a thickness of 1mm to 2mm, a length of 25mm to 40mm, and a heat capacity to working medium heat capacity ratio of 0.5 to 1.2.

[0020] Furthermore, the method for clearing the leading edge is as follows:

[0021] (1) In the flight environment of an aircraft, metallic sodium absorbs heat, melts and vaporizes, and vaporization leads to the formation of a pressure difference inside the metal shell. Under the action of the pressure difference, sodium vapor moves from the stagnation area to the low temperature area, liquefies and releases heat; finally, the liquid sodium working fluid flows back to the vicinity of the stagnation point under the capillary action of the densely packed spheres, completing a cycle;

[0022] (2) As the flight speed increases, the operating temperature of the leading edge of the aircraft rises, the sodium vapor pressure increases, and the sodium vapor enters the storage tank through the porous ceramic and pressure switch. It cools and liquefies in the storage tank. The liquefaction causes the pressure difference between the metal shell and the storage tank to increase. The pressure switch changes from the open state to the closed state, and the temperature in the storage tank decreases further. The liquid sodium working medium remains in the storage tank. The lithium working medium undergoes vaporization-movement-liquefaction-reflow.

[0023] (3) As the flight speed further increases, the operating temperature of the leading edge of the aircraft rises again, and the lithium working fluid vapor enters the storage tank and liquefies, and cannot flow back to the metal shell; the lead-bismuth alloy working fluid undergoes vaporization-movement-liquefaction-reflow.

[0024] (4) When the flight speed decreases, the working temperature of the metal shell decreases, the steam pressure inside the shell decreases, and when the pressure decreases to the critical value, the pressure switch changes from the closed state to the open state, the liquid working fluid in the storage tank flows back to the metal shell, and the heat-resistant leading edge is restored to its initial state.

[0025] The advantages of this invention compared to the prior art are:

[0026] (1) The wide temperature range heat-resistant front edge proposed in this invention, through the comprehensive design and application of three working fluids, has a wide operating temperature range and can achieve heat-resistant conduction in a wide temperature range of 600-2200℃.

[0027] (2) The working medium designed in this invention is uniformly adsorbed in the densely packed spherical capillary. It is a mixture of metallic sodium, metallic lithium and lead-bismuth alloy. The thermal structural stress is low. Compared with the single working medium conduction structure, the thermal stress is reduced by more than 50%. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0029] Figure 1 This is a schematic diagram of the wide-temperature-range heat-resistant leading edge structure according to an embodiment of the present invention;

[0030] Figure 2 The following are the temperature response curves of the leading edge structure under typical thermal conditions of Ma15: (a) is the wide-temperature-range conduction temperature response curve designed in the example, and (b) is the conduction temperature response curve of the lead working fluid.

[0031] Figure 3 This is a diagram showing the thermal stress distribution along the leading edge of the structure along its length. Detailed Implementation

[0032] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0033] This invention proposes a wide-temperature-range heat-resistant leading edge, comprising a metal shell, densely packed spherical capillaries, reinforcing ribs, working medium, lattice structure, metal pipelines, storage tank, porous ceramics, pressure switch, and cooling fins.

[0034] The metal casing has a leading edge shape with a leading edge radius of 2.5mm to 30mm. The metal casing is made of tantalum-tungsten alloy, which is 1.7mm to 3mm thick and 200mm to 300mm long.

[0035] The densely packed spherical capillary is placed on the inner surface of the metal shell 1 and is composed of multiple layers of stacked metal spheres with a diameter of 0.4 mm to 1.2 mm. The densely packed spherical capillary is made of tantalum-tungsten alloy with a thickness of 0.8 mm to 2.0 mm and a porosity of 25% to 60%.

[0036] The reinforcing ribs are placed at the weakest points of the metal shell and are integrated with the metal shell and the densely packed spheres in a single structure. They are made of the same material and have the same thickness as the metal shell, and their length is 30% to 70% of the length of the metal shell.

[0037] The working medium is uniformly adsorbed within the capillary of the densely packed spheres and is a mixture of metallic sodium, metallic lithium, and a lead-bismuth alloy. The working medium occupies 8%–15% of the volume of the metal shell, of which metallic sodium accounts for 25%–35% of the total volume, metallic lithium accounts for 25%–35% of the total volume, and the lead-bismuth alloy accounts for 30%–50% of the total volume.

[0038] The lattice structure and metal pipes are connected at one end to the metal shell and at the other end to the storage tank. The thickness of the lattice structure is 20mm–50mm, and its strength is 150MPa–200MPa. The lattice structure is a diamond-type array, with a unit cell side length of 10mm–25mm and a connecting post diameter of 1.2mm–5mm. There are 3–5 metal pipes, with an outer diameter of 8mm–15mm and a wall thickness of 1mm–2.5mm.

[0039] The porous ceramic and pressure switch are placed in separate metal pipelines, isolating the metal casing and storage tank into two semi-sealed structures. The porous ceramic has a porosity of 50%–90% and a permeability of 1.3–5 × 10⁻⁶. –10 m 2Porous ceramics include two types: alumina ceramics and YSZ ceramics, which are placed on different metal pipelines. The pressure switch is placed on a separate metal pipeline. When the pressure difference between the metal shell and the storage tank exceeds 3-5 kPa, the pressure switch changes from open to closed.

[0040] The cooling fins are connected to the bottom of the storage tank. The storage tank is made of niobium-tungsten alloy, and its volume is 3 to 10 times the volume of the working medium. The cooling fins are made of metallic copper, with a thickness of 1 mm to 2 mm and a length of 25 mm to 40 mm. The ratio of the heat capacity of the copper fins to the heat capacity of the working medium is 0.5 to 1.2.

[0041] The method for conducting heat-resistant channeling at the front edge over a wide temperature range is as follows:

[0042] (1) In high-speed flight environments, aerodynamic heating is mainly concentrated near the stagnation point at the leading edge of the aircraft. Near the stagnation point, metallic sodium absorbs heat, melting and vaporizing, leading to a small pressure difference within the metal structure. Subsequently, under the influence of this pressure difference, sodium vapor moves from the stagnation point to a low-temperature region, liquefying and releasing heat. Finally, the liquid sodium working fluid flows back to the vicinity of the stagnation point under the capillary action of the densely packed spheres, completing a cycle. Through the vaporization-movement-liquefaction-recirculation of the sodium working fluid, the metal structure achieves uniform temperature operation at a working temperature of 600-900℃, radiating the absorbed aerodynamic heating to the surrounding environment.

[0043] (2) As flight speed increases, the operating temperature at the leading edge of the aircraft rises rapidly, increasing the sodium vapor pressure. The sodium vapor enters the storage tank through the porous ceramic and pressure switch, where it cools and liquefies. Liquefaction causes a greater pressure difference between the metal shell and the storage tank, causing the pressure switch to change from open to closed. The temperature inside the storage tank further decreases, and the liquid sodium working medium remains inside. The lithium working medium undergoes vaporization-movement-liquefaction-recirculation. The metal shell achieves uniform temperature operation at an operating temperature of 900-1300℃, radiating the absorbed aerodynamic heating to the surrounding environment.

[0044] (3) As the flight speed further increases, the operating temperature of the leading edge of the aircraft rises again, and the lithium working fluid vapor also enters the storage tank and liquefies, and cannot flow back to the metal shell. The lead-bismuth working fluid undergoes vaporization-movement-liquefaction-recirculation. The metal shell achieves uniform temperature operation at an operating temperature of 1300-2200℃, radiating the absorbed aerodynamic heating to the surrounding environment.

[0045] (4) When the flight speed decreases, the working temperature of the metal shell decreases, and the vapor pressure inside the shell decreases. When the pressure decreases to a critical value, the pressure switch changes from the closed state to the open state, and the liquid working fluid in the storage tank flows back to the metal shell, and the heat shield front edge returns to its initial state.

[0046] By combining the three working fluids, the leading edge metal shell can achieve wide-temperature heat conduction and protection in an environment of 600-2200℃, thereby greatly expanding the range of heat conduction and protection thermal corridor.

[0047] The structure based on the embodiments of the present invention is as follows: Figure 1 As shown, the specific configuration is as follows: The metal shell 1 has a leading-edge shape with a leading-edge radius of 5mm. The metal shell 1 is made of tantalum-tungsten alloy, with a thickness of 2mm and a length of 240mm. The densely packed sphere capillary 2 has a thickness of 1.0mm and a porosity of 40%. The diameter of the densely packed spheres is 0.4mm. The reinforcing rib 3 has a thickness of 2mm and a length of 100mm. The working medium 4 occupies 10% of the metal shell volume. In the working medium 4, metallic sodium accounts for 30% of the total volume, metallic lithium accounts for 25%, and lead-bismuth alloy accounts for 65%. The lattice structure 5 has a thickness of 20mm and a strength of 150MPa. The lattice structure 5 is a diamond-type array with a unit cell side length of 10mm and a connecting post diameter of 2mm. There are 3 metal pipes 6. The outer diameter of the pipes is 10mm, and the pipe wall thickness is 1mm. The storage tank 7 has a volume 3-10 times that of the working medium 4. The porous ceramic element 8 comprises one piece each of alumina ceramic and YSZ ceramic, with each type of porous ceramic placed on a different metal pipe 6. The porous ceramic has a porosity of 50% and a permeability of 2×10⁻⁶. –10 m 2 The pressure switch 9 is located on a separate metal pipeline. When the pressure between the metal casing 1 and the storage tank 7 reaches 4 kPa, the pressure switch changes from open to closed. The cooling fins 10 are made of copper. The copper fins are 1.5 mm thick and 30 mm long. The ratio of the heat capacity of the copper fins to the heat capacity of the working medium 4 is 0.6.

[0048] Figure 2 Temperature response curves of the leading edge structure under typical thermal conditions at Ma15 are presented, including two cases: wide-temperature-range conduction (a) and lead-based conduction (b) designed in the examples. It can be seen that the wide-temperature-range conduction leading edge achieves isothermal operation at 800℃, while the lead-based conduction leading edge requires 1300℃ to achieve isothermal operation. The start-up temperature and temperature gradient of the wide-temperature-range conduction leading edge are both lower than those of the lead-based conduction leading edge.

[0049] Figure 3 The thermal stress distribution along the length of the leading edge structure is presented. Compared to the lead-based guiding leading edge, the maximum thermal stress of the wide-temperature-range guiding leading edge designed in this embodiment is reduced by more than 60%, which is highly beneficial for reducing leading edge stress deformation and improving structural reliability, and can effectively assist in the flight of cross-airspace, highly maneuverable aircraft.

[0050] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A wide-temperature-range heat-insulating leading edge, characterized in that, It includes a metal shell, densely packed spherical capillary structure, reinforcing ribs, working medium, lattice structure, metal pipeline, storage tank, porous ceramics, pressure switch and cooling fins; The metal shell has a leading edge shape and is connected to the storage tank through multiple metal pipes at the tail end face; there are three or more metal pipes, two of which are equipped with porous ceramics, one of which is equipped with a pressure switch, and the remaining metal pipes are equipped with either porous ceramics or pressure switches. The densely packed spherical capillary structure is placed on the inner surface of the metal shell, and multiple working media are uniformly adsorbed in the densely packed spherical capillary structure. The reinforcing ribs are installed inside the metal shell to improve the rigidity of the metal shell; The dot matrix structure is disposed between the metal shell and the storage tank; The cooling fins are connected to the bottom of the storage tank; The working medium occupies 8% to 15% of the volume of the metal shell. The working medium is a mixture of sodium metal, lithium metal and lead-bismuth alloy, wherein sodium metal accounts for 25% to 35% of the volume of the working medium, lithium metal accounts for 25% to 35% of the volume of the working medium, and lead-bismuth alloy accounts for 30% to 50% of the volume of the working medium.

2. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, The metal shell, densely packed spherical capillary structure, and reinforcing ribs are integrated into one structure, and are all made of tantalum-tungsten alloy.

3. The wide-temperature-range heat-resistant leading edge according to claim 1 or 2, characterized in that, The thickness of the densely packed spherical capillary structure is 0.8 mm to 2.0 mm, and the porosity is 25% to 60%.

4. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, The thickness of the lattice structure is 20mm~50mm, and the strength is 150MPa~200MPa. The lattice structure is a diamond array with a unit cell side length of 10mm~25mm and a connecting post diameter of 1.2mm~5mm.

5. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, Porous ceramics have a porosity of 50%–90% and a permeability of 1.3 × 10⁻⁶. –10 m²~5×10 –10 m².

6. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, The pressure switch is placed on a separate metal pipeline. When the pressure difference between the metal housing and the storage tank is greater than 3 kPa, the pressure switch changes from open to closed, isolating the metal housing and the storage tank into two sealed structures.

7. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, The storage tank is made of niobium-tungsten alloy, and its volume is 3 to 10 times the volume of the working medium.

8. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, The cooling fins have a thickness of 1mm to 2mm, a length of 25mm to 40mm, and a heat capacity to working medium heat capacity ratio of 0.5 to 1.

2.

9. The wide-temperature-range heat-resistant leading edge according to claim 1, characterized in that, The method for clearing the leading edge is as follows: (1) In the flight environment of the aircraft, metallic sodium absorbs heat, melts and vaporizes, and vaporization leads to the formation of a pressure difference in the metal shell; under the action of the pressure difference, sodium vapor moves from the stagnation area to the low temperature area, liquefies and releases heat; finally, the liquid sodium working medium flows back to the vicinity of the stagnation point under the capillary action of the densely packed spheres, completing a cycle; (2) As the flight speed increases, the operating temperature of the leading edge of the aircraft rises, the sodium vapor pressure increases, and the sodium vapor enters the storage tank through the porous ceramic and pressure switch. It is cooled and liquefied in the storage tank. The liquefaction causes the pressure difference between the metal shell and the storage tank to increase. The pressure switch changes from the open state to the closed state, and the temperature in the storage tank decreases further. The liquid sodium working medium stays in the storage tank; the lithium working medium undergoes vaporization-movement-liquefaction-recirculation. (3) As the flight speed further increases, the operating temperature of the leading edge of the aircraft rises again, the lithium working medium vapor enters the storage tank and liquefies, and cannot flow back to the metal shell; the lead-bismuth alloy working medium undergoes vaporization-movement-liquefaction-reflow. (4) When the flight speed decreases, the working temperature of the metal shell decreases, the steam pressure inside the shell decreases, and when the pressure decreases to the critical value, the pressure switch changes from the closed state to the open state, the liquid working medium in the storage tank flows back to the metal shell, and the heat-resistant leading edge is restored to its initial state.

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