High-thermal-conductivity spontaneous-sweating heatproof end

Abstract

The invention discloses a high-thermal-conductivity spontaneous sweating heat-proof end, and belongs to the technical field of thermal protection of high-speed aircrafts. The end comprises a heat dredging structure, a heat transfer structure, a sweating working medium, a storage tank, a pressure switch, a spiral vapor-liquid separator, a metal pipeline and a porous structure. The sweating working medium is arranged in the storage tank, and the storage tank is connected with the spiral vapor-liquid separator through the pressure switch. One end of the heat transfer structure is connected with the heat dredging structure, and the other end of the heat transfer structure extends into the sweating working medium. The porous structure is arranged in an end stagnation point area, one end of the metal pipeline is communicated with the spiral vapor-liquid separator, and the other end of the metal pipeline is communicated with the porous structure. Pneumatic heating serves as a power source, the power of the power source is adjusted through heat dredging and heat transfer, and high-heat-conduction spontaneous perspiration cooling of the end structure is achieved.

Description

Technical Field

[0001] The invention relates to a high-thermal-conductivity self-sweating heat-proof terminal, belonging to the technical field of heat protection of high-speed aircraft. Background Art

[0002] With the emergence and development of high-speed aircraft, the operating temperature of aircraft terminals is getting higher and higher, reaching or even exceeding the operating temperature limit of existing heat protection material systems. The thermal protection of the terminals faces severe challenges. Sweating cooling is one of the feasible ways to solve this problem.

[0003] Common sweating structures are mainly composed of storage tanks, sweating working fluids, power sources, metal pipelines, porous structures, etc. The principle of sweating cooling is: through the power source doing work, the sweating working fluid storage tank is transported to the porous structure, and then injected into the aerodynamic environment near the stagnation point to isolate the aerodynamic heating to achieve the cooling function. Since the sweating working fluid cooling is not completely matched with the aerodynamic thermal environment, an excess of working fluid must be transported to the porous structure to ensure the sweating cooling effect. That is, the traditional sweating cooling system has application problems such as large working fluid consumption, high energy consumption, and high usage compensation. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, and to propose a high thermal conductivity self-sweating heat-proof terminal, which uses pneumatic heating as a power source, adjusts the power source power through heat conduction and heat transfer, and realizes high thermal conductivity self-sweating cooling of the terminal structure. At the same time, a vapor-liquid separation structure is introduced into the terminal, which can prevent excessive sweating medium from being ejected outward to the greatest extent, thereby reducing the amount of sweating medium used and reducing the compensation of the sweating cooling system.

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

[0006] A high thermal conductivity self-sweating heat-proof terminal, comprising a heat conduction structure, a heat transfer structure, a sweating medium, a storage tank, a pressure switch, a spiral vapor-liquid separator, a metal pipeline, and a porous structure;

[0007] The sweating medium is placed in a storage tank, which is connected to the spiral vapor-liquid separator via a pressure switch;

[0008] The heat conduction structure is in a spherical cone shape, one end of the heat transfer structure is connected to the heat conduction structure, and the other end extends into the sweating medium;

[0009] The porous structure is placed in the end stationary point area, one end of the metal pipeline is connected to the spiral vapor-liquid separator, and the other end is connected to the porous structure.

[0010] Furthermore, the heat transfer structure is 3 to 10 potassium-sodium alloy pulsating heat pipes, each of which has an outer diameter of 6 mm to 10 mm, a wall thickness of 0.5 mm to 2 mm, and a length of 120 mm to 300 mm.

[0011] Furthermore, the length of the heat transfer structure extending into the sweating medium is adjustable within a range of 0 to 100 mm.

[0012] Furthermore, the sweating medium is metallic zinc with a purity greater than 99% and a volume of 0.5-3L.

[0013] Furthermore, the storage tank is made of niobium alloy, the tank wall thickness is 0.5mm to 3mm, and the structural strength is greater than 250MPa.

[0014] Furthermore, the spiral gas-liquid separator is in the shape of a barrel, and metal copper balls are densely stacked in the barrel, and the diameter of the metal copper balls is 2mm to 10mm; there is a spiral channel in the spiral gas-liquid separator, and the gap between the metal copper balls and the spiral channel are interconnected. The diameter of the spiral channel is 2mm to 8mm, and the number of turns is 3 to 10.

[0015] Furthermore, the material of the metal pipeline is the same as that of the heat conduction structure, the outer diameter of the metal pipeline is 4 mm to 10 mm, and the wall thickness is 0.8 mm to 2.0 mm.

[0016] Furthermore, the porous structure is a niobium-based lattice structure, the lattice structure has a porosity of 20% to 45%, an open porosity of greater than 95%, and a structural strength of greater than 50 MPa.

[0017] Furthermore, the heat conduction structure is an integrated niobium alloy / lithium working medium high temperature heat pipe, with a leading edge radius of 5mm to 35mm, a length of 140mm to 480mm, and an equivalent density of 800kg / m 3 ~4400kg / m 3 .

[0018] Furthermore, the method for the terminal to perform high thermal conductivity self-sweating is:

[0019] In a high-speed flight environment, aerodynamic heating causes the heat transfer medium in the heat transfer structure to melt and vaporize, forming a pressure difference in the heat transfer structure; under the action of the pressure difference, the heat transfer medium vapor moves from the stagnation area to the low-temperature area of ​​the heat transfer structure, liquefies, and releases heat; the liquid heat transfer medium flows back to the stagnation area under the action of capillary force, completing a cycle;

[0020] As the flight speed increases, the amount of heat entering the terminal increases, the working temperature of the heat conduction structure increases, and the heat is transported to the sweating medium in the storage tank through the heat transfer structure. The sweating medium vaporizes and increases the pressure in the storage tank. When the sweating medium vapor pressure reaches a critical value, the pressure switch changes from a closed state to an open state, and the sweating medium vapor is sprayed to the vicinity of the terminal stagnation point through a spiral vapor-liquid separator, a metal pipeline, and a porous structure, isolating the aerodynamic heating environment from the heat-proof terminal, thereby reducing the aerodynamic heating effect and lowering the working temperature of the heat-proof terminal.

[0021] When the aircraft speed decreases, the heat absorption of the heat conduction structure decreases, and the heat entering the storage tank also decreases accordingly. The temperature of the sweating working fluid drops, the steam pressure decreases, and the pressure switch changes from the open state back to the closed state.

[0022] The advantages of the present invention compared with the prior art are:

[0023] (1) The present invention uses less working fluid and does not require a power source device, which can significantly reduce the weight of the sweat cooling system and has low usage compensation.

[0024] (2) The end head designed in the present invention also introduces a vapor-liquid separation structure, which can prevent excessive sweating medium from being ejected outward to the greatest extent, thereby reducing the amount of sweating medium used and reducing the compensation of the sweating cooling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Figure 1 This is a schematic diagram of a high thermal conductivity self-sweating heat-proof terminal according to an embodiment of the present invention;

[0027] Figure 2 This is a heat flow distribution diagram on the surface of the spherical cone-shaped end head according to an embodiment of the present invention;

[0028] Figure 3 This is a diagram showing the cooling effect of the stagnation point of the spherical cone-shaped end in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] The invention proposes a high thermal conductivity self-sweating heat-proof terminal, which comprises a heat conduction structure, a heat transfer structure, a sweating medium, a storage tank, a pressure switch, a spiral vapor-liquid separator, a metal pipeline and a porous structure.

[0031] The heat conduction structure is spherical and conical, and is an integrated niobium alloy / lithium working medium high-temperature heat pipe. The front edge radius of the high-temperature heat pipe is 5-35mm, the length is 140-480mm, and the equivalent density is 800-4400kg / m 3 .

[0032] One end of the heat transfer structure is connected to the heat conduction structure, and the other end extends into the sweating medium, and the extension length can be adjusted within a range of 0 to 100 mm. Preferably, the heat transfer structure is 3 to 10 potassium-sodium alloy pulsating heat pipes, with an outer diameter of 6 to 10 mm, a wall thickness of 0.5 to 2 mm, and a length of 120 to 300 mm.

[0033] The sweating medium is placed in a storage tank, which is made of metal zinc with a purity greater than 99% and a volume of 0.5 to 3 L. The sweating medium mass flow rate can be obtained based on the typical working pressure of the sweating medium and the diameter of the metal pipeline, and then multiplied by the flight time to obtain the sweating medium usage.

[0034] The storage tank is connected to the spiral gas-liquid separator through a pressure switch. The storage tank is made of niobium alloy, with a wall thickness of 0.5 to 3 mm and a structural strength greater than 250 MPa. The pressure switch is normally closed, and its opening pressure is 0.1 to 0.8 MPa.

[0035] The material of the metal pipeline is the same as that of the heat conduction structure. The outer diameter of the metal pipeline is 4 to 10 mm and the wall thickness is 0.8 to 2.0 mm. One end of the metal pipeline is connected to the spiral gas-liquid separator, and the other end is connected to the porous structure. The spiral gas-liquid separator is in the shape of a barrel, and the metal copper balls are densely stacked in the barrel. The gaps between the metal copper balls and the spiral channel are interconnected. The diameter of the metal copper balls is 2-10 mm. There is a spiral channel in the spiral gas-liquid separator, the diameter of the spiral channel is 2 to 8 mm, and the number of turns is 3 to 10.

[0036] The porous structure is placed in the end stationary point area, the porous structure is a niobium-based lattice structure, the lattice structure has a porosity of 20% to 45%, an open porosity of more than 95%, and a structural strength of more than 50MPa.

[0037] The working principle of the present invention is:

[0038] (1) In a high-speed flight environment, aerodynamic heating is mainly concentrated near the stagnation point at the end of the aircraft. The area near the stagnation point absorbs heat, and the heat conduction fluid in the heat conduction structure (integrated niobium alloy / lithium working fluid high-temperature heat pipe) melts and vaporizes. Vaporization causes a small pressure difference to form in the heat conduction structure. Subsequently, under the action of the pressure difference, the vapor of the heat conduction fluid moves from the vicinity of the stagnation point to the low-temperature area of ​​the heat conduction structure, liquefies, and releases heat. Finally, the liquid heat conduction fluid flows back to the area near the stagnation point under the action of capillary force, completing a cycle. Through the vaporization-movement-liquefaction-reflux of the heat conduction fluid, the heat conduction structure achieves uniform temperature operation at a low operating temperature and radiates the absorbed aerodynamic heating to the surrounding environment.

[0039] (2) As the flight speed increases, the amount of heat entering the terminal increases rapidly, the working temperature of the heat conduction structure increases, and the heat is transferred to the sweating working fluid in the storage tank through the heat transfer structure. The sweating working fluid vaporizes, causing the pressure in the storage tank to increase. When the sweating working fluid vapor pressure reaches a certain critical value, the pressure switch changes from the closed state to the open state, and the sweating working fluid vapor is sprayed to the vicinity of the terminal stagnation point through the spiral vapor-liquid separator, metal pipeline, and porous structure, isolating the aerodynamic heating environment and the heat protection terminal, thereby reducing the aerodynamic heating effect and reducing the working temperature of the heat protection terminal.

[0040] (3) When the aircraft speed decreases, the heat absorption of the heat conduction structure decreases, and the heat entering the storage tank also decreases accordingly. The temperature of the sweating medium decreases, the steam pressure decreases, and the pressure switch changes from the open state to the closed state, and the heat protection end head re-enters the heat conduction-radiation heat dissipation working mode. Through the control of the pressure switch, the heat protection end head can minimize the excessive sweating medium from being ejected outward, thereby reducing the amount of sweating medium used and reducing the compensation of the sweating cooling system.

[0041] Based on the implementation of the present invention, for example Figure 1 As shown, the heat conduction structure 1 is an integrated niobium alloy / lithium working medium high-temperature heat pipe, the high-temperature heat pipe front edge radius is 8mm, the length is 250mm, and the equivalent density is 2600kg / m 3 . The heat transfer structure 2 is composed of three potassium-sodium alloy pulsating heat pipes. The outer diameter of the pulsating heat pipe is 6mm, the wall thickness is 1mm, and the length is 150mm. The potassium-sodium alloy pulsating heat pipe extends into the sweating medium 3, and the extension length is 50mm. The sweating medium 3 is metallic zinc, the purity of metallic zinc is 99.2%, and the volume is 1.2L. The wall thickness of the niobium alloy tank 4 is 2.5mm, and the structural strength is about 300MPa. The pressure switch 5 is in a normally closed state, and the opening pressure is 0.2MPa. The spiral vapor-liquid separator 6 is in the shape of a cylinder, and metal copper balls with a diameter of 3mm are densely stacked in the barrel. The spiral channel in the separator 6 has a diameter of 5mm and 3 turns. The gap between the metal copper balls and the spiral channel are interconnected. The metal pipeline 7 is made of niobium alloy, with an outer diameter of 8mm and a wall thickness of 1mm. The porous structure 8 is a niobium-based lattice structure, and the lattice structure 8 has a porosity of 35%, an open porosity of 97%, and a structural strength of 80MPa.

[0042] Figure 2 The heat flux distribution on the tip surface of this embodiment under the Mach 14 flight environment is given. On the one hand, the heat flux on the tip surface decreases rapidly in the front-to-back direction, and the aerodynamic heating is mainly concentrated near the tip stagnation point area. On the other hand, the heat flux distribution on the tip surface is also affected by sweating. After the introduction of sweating cooling, the heat flux at the tip stagnation point is reduced by about 50%. Figure 3 The cooling effect of the terminal stagnation point of this embodiment is given. It can be seen that after the introduction of spontaneous sweating cooling, the terminal stagnation point temperature is reduced from 1700°C to 1100°C. Metal materials can be used instead of composite materials for thermal structure design, which greatly reduces the difficulty of achieving thermal protection.

[0043] 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 high thermal conductivity self-sweating heat-proof terminal, characterized in that: It includes heat conduction structure, heat transfer structure, sweating medium, storage tank, pressure switch, spiral vapor-liquid separator, metal pipeline and porous structure; The sweating medium is placed in a storage tank, which is connected to the spiral vapor-liquid separator via a pressure switch; The heat conduction structure is in a spherical cone shape, and contains a conduction medium inside; one end of the heat transfer structure is connected to the heat conduction structure, and the other end extends into the sweating medium; The porous structure is placed in the end stationary point area, one end of the metal pipeline is connected to the spiral vapor-liquid separator, and the other end is connected to the porous structure.

2. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The heat transfer structure comprises 3 to 10 potassium-sodium alloy pulsating heat pipes, each of which has an outer diameter of 6 mm to 10 mm, a wall thickness of 0.5 mm to 2 mm, and a length of 120 mm to 300 mm.

3. The high thermal conductivity self-sweating heat-proof terminal according to claim 1 or 2, characterized in that: The length of the heat transfer structure extending into the sweating medium is adjustable within a range of 0 to 100 mm.

4. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The sweating medium is metallic zinc with a purity greater than 99% and a volume of 0.5L to 3L.

5. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The storage tank is made of niobium alloy, the tank wall thickness is 0.5mm to 3mm, and the structural strength is greater than 250MPa.

6. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The spiral gas-liquid separator is in the shape of a barrel, and metal copper balls are densely piled in the barrel, and the diameter of the metal copper balls is 2mm-10mm; there is a spiral channel in the spiral gas-liquid separator, and the gap between the metal copper balls and the spiral channel are interconnected.

7. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The material of the metal pipeline is the same as that of the heat conduction structure, the outer diameter of the metal pipeline is 4mm-10mm, and the wall thickness is 0.8mm-2.0mm.

8. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The porous structure is a niobium-based lattice structure, the lattice structure has a porosity of 20% to 45%, an open porosity of more than 95%, and a structural strength of more than 50 MPa.

9. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The heat conduction structure is an integrated niobium alloy / lithium working medium high-temperature heat pipe, the front edge radius of the high-temperature heat pipe is 5mm-35mm, the length is 140mm-480mm, and the equivalent density is 800kg / m 3 ~4400kg / m 3 .

10. The high thermal conductivity self-sweating heat-proof terminal according to claim 1, characterized in that: The method of high thermal conductivity self-sweating of the end is: In the flight environment of the aircraft, aerodynamic heating causes the heat conduction medium in the heat conduction structure to melt and vaporize, forming a pressure difference in the heat conduction structure; under the action of the pressure difference, the vapor of the heat conduction medium moves from the stagnation area to the low-temperature area of ​​the heat conduction structure, liquefies, and releases heat; the liquid heat conduction medium flows back to the stagnation area under the action of capillary force, completing a cycle; As the flight speed increases, the amount of heat entering the terminal increases, the working temperature of the heat conduction structure increases, and the heat is transported to the sweating medium in the storage tank through the heat transfer structure. The sweating medium vaporizes and increases the pressure in the storage tank. When the sweating medium vapor pressure reaches a critical value, the pressure switch changes from a closed state to an open state, and the sweating medium vapor is sprayed to the vicinity of the terminal stagnation point through a spiral vapor-liquid separator, a metal pipeline, and a porous structure, isolating the aerodynamic heating environment from the heat-proof terminal, thereby reducing the aerodynamic heating effect and lowering the working temperature of the heat-proof terminal. When the aircraft speed decreases, the heat absorption of the heat conduction structure decreases, and the heat entering the storage tank also decreases accordingly. The temperature of the sweating working fluid drops, the steam pressure decreases, and the pressure switch changes from the open state back to the closed state.

Images