Wide-temperature-zone dredging heatproof leading edge

Abstract

The invention discloses a wide-temperature-zone dredging heat-proof leading edge, and belongs to the technical field of thermal protection of high-speed aircrafts. The structure comprises a metal shell, densely-stacked ball capillary, reinforcing ribs, a working medium, a lattice structure, a metal pipeline, a storage tank, porous ceramics, a pressure switch and cooling fins. Wherein the metal shell is in the shape of a front edge. The densely-packed ball capillary is arranged on the inner surface of the metal shell, and the working medium is evenly adsorbed in the densely-packed ball capillary. The lattice 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 ceramic and the pressure switch are arranged in different metal pipelines respectively, and the metal shell and the storage tank are isolated into two semi-sealed structures. The cooling fins are connected with the bottom of the storage tank. The dredging use temperature range is 600-2200 DEG C, the thermal stress of the dredging front edge can be greatly reduced, and the reliability and safety of dredging type thermal protection are improved.

Description

Technical Field

[0001] The invention relates to a wide temperature range dredging heat protection leading edge, belonging to the technical field of high-speed aircraft heat protection. Background Art

[0002] The leading edge temperature of high-speed aircraft is getting higher and higher, reaching or even exceeding the upper limit of the existing thermal protection material system. Conductive thermal protection is one of the feasible ways to solve this problem.

[0003] Common drainage structures include nickel-based drainage structures, niobium-based drainage structures, molybdenum-based drainage structures, and tantalum-based drainage structures. Among them, the use temperature of the nickel-based drainage structure is 600-1100°C, the use temperature of the niobium-based drainage structure is 900-1400°C, the use temperature of the molybdenum-based drainage structure is 1000-1800°C, and the use temperature of the tantalum-based drainage structure is 1300-2200°C. Due to the narrow use temperature range of the drainage structure, the drainage-type thermal protection application faces serious thermal stress problems and is difficult to apply to the leading edge heat protection of cross-airspace, highly maneuverable aircraft. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a wide temperature range dredging heat protection front edge, the dredging temperature range can be expanded to 600-2200°C, the thermal stress of the dredging front edge can be greatly reduced, and the reliability and safety of the dredging type thermal protection can be improved.

[0005] The technical solution of the present invention is:

[0006] A wide temperature range dredge heat protection front edge, comprising a metal shell, a dense ball capillary structure, reinforcing ribs, a working medium, a lattice structure, a metal pipeline, a storage tank, a porous ceramic, a pressure switch and a cooling fin;

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

[0008] The densely packed ball capillary structure is placed on the inner surface of the metal shell, and a plurality of working media are uniformly adsorbed in the densely packed ball capillary structure;

[0009] The reinforcing ribs are arranged in the metal shell to improve the rigidity of the metal shell;

[0010] The lattice structure is arranged 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 dense ball capillary structure and the reinforcing ribs are an integrated structure, and the materials are all tantalum-tungsten alloy.

[0013] Furthermore, the thickness of the densely packed ball 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 metallic sodium, metallic lithium and lead-bismuth alloy, wherein metallic sodium occupies 25% to 35% of the volume of the working medium, metallic lithium occupies 25% to 35% of the volume of the working medium, and lead-bismuth alloy occupies 30% to 50% of the volume of the working medium.

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

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

[0017] Furthermore, the pressure switch is placed on a separate metal pipeline. When the pressure difference between the metal shell and the storage tank is greater than 3KPa, the pressure switch changes from open to closed, so that the metal shell and the storage tank are isolated into two sealed structures.

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

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

[0020] Furthermore, the method of leading edge grooming is:

[0021] (1) In the flight environment of an aircraft, metallic sodium absorbs heat, melts, and vaporizes, which causes a pressure difference to form inside the metal shell. Under the action of the pressure difference, the sodium vapor moves from the stagnation point 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 balls, completing a cycle;

[0022] (2) As the flight speed increases, the operating temperature of the leading edge of the aircraft increases, the sodium vapor pressure increases, and the sodium vapor enters the storage tank through the porous ceramic and the pressure switch, and is cooled and liquefied in the storage tank. The liquefaction causes the pressure difference between the metal shell and the storage tank to increase, and the pressure switch changes from the open state to the closed state. The temperature in the storage tank further decreases, and the liquid sodium working fluid stays in the lower storage tank; the lithium working fluid undergoes vaporization-movement-liquefaction-reflux;

[0023] (3) As the flight speed increases further, the operating temperature at the leading edge of the aircraft rises again, 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 vaporizes-moves-liquefies-backflows;

[0024] (4) When the flight speed decreases, the working temperature of the metal shell decreases, and the steam pressure in the shell decreases. When the pressure decreases to a critical value, the pressure switch changes from the closed state back to the open state, and the liquid working fluid in the storage tank flows back to the metal shell, guiding the heat protection front edge to return to its initial state.

[0025] The advantages of the present invention compared with the prior art are:

[0026] (1) The wide temperature range heat-conducting and heat-protecting front edge proposed by the present invention has a wide operating temperature range through the comprehensive design and application of three working fluids, and can achieve heat-conducting and heat-protecting in a wide temperature range of 600-2200°C.

[0027] (2) The working medium designed by the present invention is uniformly adsorbed in the densely packed ball capillaries and is a mixture of metallic sodium, metallic lithium and lead-bismuth alloy. The thermal structural stress is low. Compared with a single working medium conducting structure, the thermal stress is reduced by more than 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

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

[0030] Figure 2 The temperature response curve of the leading edge structure under the typical thermal environment of Ma15, (a) is the wide temperature range dredging temperature response curve designed in the embodiment, (b) is the lead working fluid dredging temperature response curve;

[0031] Figure 3 This is the thermal stress distribution diagram of the leading edge structure along the length direction. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0033] The invention proposes a wide temperature range dredge heat protection front edge, comprising a metal shell, densely packed ball capillaries, reinforcing ribs, a working medium, a lattice structure, a metal pipeline, a storage tank, porous ceramics, a pressure switch and cooling fins.

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

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

[0036] The reinforcing rib is placed at the weak position of the metal shell and is integrated with the metal shell and the densely packed ball capillary. The material and thickness are the same as those of the metal shell, and the length is 30% to 70% of the length of the metal shell.

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

[0038] One end of the lattice structure and the metal pipeline is connected to the metal shell, and the other end is connected to the storage tank. The thickness of the lattice structure is 20mm~50mm, and the strength is 150MPa~200MPa. The lattice structure is a diamond-shaped array, with a single cell side length of 10mm~25mm and a connecting column diameter of 1.2mm~5mm. There are 3~5 metal pipelines, with an outer diameter of 8mm~15mm and a wall thickness of 1mm~2.5mm.

[0039] The porous ceramic and the pressure switch are placed in different metal pipes, isolating the metal shell and the storage tank into two semi-sealed structures. The porous ceramic has a porosity of 50% to 90% and a permeability of 1.3 to 5×10 –10 m 2Porous ceramics include alumina ceramics and YSZ ceramics, and the two porous ceramics 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 is greater than 3-5kPa, the pressure switch changes from open to closed.

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

[0041] The method of dredging the wide temperature zone heat protection front edge is:

[0042] (1) In a high-speed flight environment, aerodynamic heating is mainly concentrated near the stagnation point at the leading edge of the aircraft. The metallic sodium near the stagnation point absorbs heat, melts, and vaporizes. The vaporization causes a small pressure difference to form in the metal structure. Subsequently, under the action of the pressure difference, the sodium vapor moves from the low-temperature area near the stagnation point, 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 balls, completing a cycle. Through the vaporization-movement-liquefaction-reflux of the sodium working fluid, the metal structure achieves uniform temperature operation at an operating temperature of 600-900℃, radiating the absorbed aerodynamic heating to the surrounding environment.

[0043] (2) As the flight speed increases, the operating temperature of the leading edge of the aircraft rises rapidly, the sodium vapor pressure increases, and the sodium vapor enters the storage tank through the porous ceramic and the pressure switch, and is cooled and liquefied in the storage tank. The liquefaction causes the pressure difference between the metal shell and the storage tank to increase, and the pressure switch changes from the open state to the closed state. The temperature in the storage tank further decreases, and the liquid sodium working fluid stays in the storage tank. The lithium working fluid vaporizes-moves-liquefies-refluxes. The metal shell achieves uniform temperature operation at an operating temperature of 900-1300℃, radiating the absorbed aerodynamic heat to the surrounding environment.

[0044] (3) As the flight speed increases further, 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 vaporizes-moves-liquefies-backflows. The metal shell achieves uniform temperature operation at an operating temperature of 1300-2200℃, radiating the absorbed aerodynamic heat to the surrounding environment.

[0045] (4) When the flight speed decreases, the working temperature of the metal shell decreases, and the steam pressure in 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, guiding the heat protection front edge to return to its initial state.

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

[0047] Based on the embodiment structure of the present invention Figure 1 As shown, the specific configuration is as follows: the metal shell 1 has a leading edge shape, and the leading edge radius is 5mm. The material of the metal shell 1 is tantalum-tungsten alloy, which is 2mm thick and 240mm long. The dense ball capillary 2 has a thickness of 1.0mm and a porosity of 40%. The diameter of the metal ball used for the dense ball is 0.4mm. The reinforcing rib 3 is 2mm thick and 100mm long. The working medium 4 accounts for 10% of the volume of the metal shell. In the working medium 4, metallic sodium accounts for 30% of the total volume, metallic lithium accounts for 25% of the total volume, and the lead-bismuth alloy accounts for 65% of the total volume. The lattice structure 5 is 20mm thick and has a strength of 150MPa. The lattice structure 5 is a diamond-shaped array, and its unit cell side length is 10mm and the connecting column diameter is 2mm. There are 3 metal pipelines 6. The outer diameter of the pipeline is 10mm and the wall thickness is 1mm. The volume of the storage tank 7 is 3-10 times the volume of the working medium 4. The porous ceramic 8 includes one piece of alumina ceramic and one piece of YSZ ceramic, and the two porous ceramics are placed on different metal pipes 6. The porous ceramic has a porosity of 50% and a permeability of 2×10 –10 m 2 The pressure switch 9 is placed on a separate metal pipeline. When the pressure of the metal housing 1 and the storage tank 7 is 4 kPa, the pressure switch changes from on to off. The cooling fin 10 is made of metal copper. The copper fin is 1.5 mm thick and 30 mm long. The ratio of the heat capacity of the copper fin to the heat capacity of the working medium 4 is 0.6.

[0048] Figure 2 The temperature response curve of the leading edge structure under the typical thermal environment of Ma15 is given, including the wide temperature range dredging (a) and lead working fluid dredging (b) designed in the embodiment. It can be seen that the wide temperature range dredging leading edge achieves isothermal operation at 800°C, while the lead working fluid dredging leading edge needs to achieve isothermal operation at 1300°C. The starting temperature and temperature gradient of the wide temperature dredging leading edge are lower than those of the lead working fluid dredging leading edge.

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

[0050] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A wide temperature range dredging heat protection front edge, characterized in that: It includes a metal shell, a dense ball capillary structure, reinforcing ribs, a working medium, a lattice structure, a metal pipeline, a storage tank, porous ceramics, a pressure switch and cooling fins; The metal shell has a leading edge shape and is connected to the storage tank through multiple metal pipelines at the rear end face; there are more than three metal pipelines, two of which are provided with porous ceramics, one of which is provided with a pressure switch, and the remaining metal pipelines are provided with either porous ceramics or pressure switches; The densely packed ball capillary structure is placed on the inner surface of the metal shell, and a plurality of working media are uniformly adsorbed in the densely packed ball capillary structure; The reinforcing ribs are arranged in the metal shell to improve the rigidity of the metal shell; The lattice structure is arranged between the metal shell and the storage tank; The cooling fins are connected to the bottom of the storage tank.

2. The wide temperature range dredging heat protection front edge according to claim 1, characterized in that: The metal shell, the dense ball capillary structure and the reinforcing ribs are integrated structures, and are all made of tantalum-tungsten alloy.

3. The wide temperature range dredging heat protection front edge according to claim 1 or 2, characterized in that: The densely packed ball capillary structure has a thickness of 0.8 mm to 2.0 mm and a porosity of 25% to 60%.

4. The wide temperature range dredging heat protection front edge according to claim 1, characterized in that: The working medium occupies 8% to 15% of the volume of the metal shell, and the working medium is a mixture of metallic sodium, metallic lithium and lead-bismuth alloy, wherein metallic sodium occupies 25% to 35% of the volume of the working medium, metallic lithium occupies 25% to 35% of the volume of the working medium, and lead-bismuth alloy occupies 30% to 50% of the volume of the working medium.

5. The wide temperature range dredging heat protection front edge according to claim 1, characterized in that: The lattice structure has a thickness of 20 mm to 50 mm and a strength of 150 MPa to 200 MPa; the lattice structure is a diamond-shaped array, the side length of a single cell is 10 mm to 25 mm, and the diameter of a connecting column is 1.2 mm to 5 mm.

6. The wide temperature range dredging heat protection front edge according to claim 1, characterized in that: The porosity of porous ceramics is 50% to 90%, and the permeability is 1.3×10 –10 m 2 ~5×10 –10 m 2 .

7. The wide temperature range dredging heat protection front 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 shell and the storage tank is greater than 3KPa, the pressure switch changes from open to closed, isolating the metal shell and the storage tank into two sealed structures.

8. The wide temperature range dredging heat protection front edge according to claim 1, characterized in that: The storage tank is made of niobium-tungsten alloy, and the volume of the storage tank is 3 to 10 times the volume of the working medium.

9. The wide temperature range dredging heat protection front edge according to claim 1, characterized in that: The thickness of the cooling fin is 1 mm to 2 mm, the length is 25 mm to 40 mm, and the ratio of the heat capacity to the heat capacity of the working medium is 0.5 to 1.

2.

10. The wide temperature range dredging heat protection front edge according to claim 4, characterized in that: The method of leading edge grooming is: (1) In the flight environment of an aircraft, metallic sodium absorbs heat, melts, and vaporizes. The vaporization causes a pressure difference to form inside the metal shell. Under the action of the pressure difference, the sodium vapor moves from the stagnation point 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 balls, completing a cycle. (2) As the flight speed increases, the operating temperature of the leading edge of the aircraft increases, the sodium vapor pressure increases, and the sodium vapor enters the storage tank through the porous ceramic and the pressure switch, and is cooled and liquefied in the storage tank. The liquefaction causes the pressure difference between the metal shell and the storage tank to increase, and the pressure switch changes from the open state to the closed state. The temperature in the storage tank further decreases, and the liquid sodium working fluid stays in the lower storage tank; the lithium working fluid undergoes vaporization-movement-liquefaction-reflux; (3) As the flight speed increases further, the operating temperature at the leading edge of the aircraft rises again, 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 vaporizes-moves-liquefies-backflows; (4) When the flight speed decreases, the working temperature of the metal shell decreases, and the steam pressure in the shell decreases. When the pressure decreases to a critical value, the pressure switch changes from the closed state back to the open state, and the liquid working fluid in the storage tank flows back to the metal shell, guiding the heat protection front edge to return to its initial state.

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