Composite heat-shielding structure and preparation method thereof

Abstract

The present application relates to a kind of composite dredging type non-ablation heat protection structure and its preparation method, which integrates steam cavity heat pipe and pulsating heat pipe flow channel;Steam cavity heat pipe starts under the heating of pulsating heat pipe flow channel, vapor flow cavity different regions occur phase change of working medium evaporation, vapor flow, vapor condensation, in the working medium condensation region, gaseous working medium capillary structure condenses, condensing working medium is transported by heat pipe channel from working medium condensation region to working medium evaporation phase transition region under the joint action of capillary force and gas pressure, after being transported to working medium evaporation phase transition region, it is phase transition into gaseous working medium, and so on, it is recycled, the heat flow inputted by pulsating heat pipe flow channel is dissipated in the form of full surface area radiation heat dissipation and reaches equilibrium state.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerospace high-speed vehicle aerodynamic heat protection system, and proposes a composite guiding type non-ablation heat protection structure and a preparation method thereof suitable for different aerodynamic heating environments. BACKGROUND

[0002] When an aerospace high-speed vehicle flies in the earth's atmosphere, the intense impact and friction of high-speed solid wall surface with atmospheric gas molecules cause the gas temperature to rise sharply, and the gas heat is continuously transmitted to the surface of the vehicle, resulting in aerodynamic heating effect. In order to prevent high temperature caused by aerodynamic heating from damaging the safety of the vehicle structure, a special material or structure is usually designed on the surface of the vehicle to control the influence of surface heat transfer, so as to ensure the safety of the internal structure of the vehicle, which is also called a vehicle heat protection system. Among them, the guiding type heat protection system is a kind of efficient heat protection technology scheme.

[0003] The guiding type heat protection structure utilizes the principle of heat pipe, and uses the extremely high heat transfer power of heat pipe technology to "guide" the aerodynamic heating heat of the local high heat flow area to a large area of the heat protection structure with lower aerodynamic heat flow, and then the heat is discharged through the large-area radiation heat dissipation mechanism, so as to realize the way of "peak filling" to reduce the peak temperature of the structure and improve the radiation heat dissipation power. The traditional guiding type heat protection adopts steam cavity type heat pipe as the core guiding mechanism, but it has the disadvantages of long starting time and weak adaptability to high heat flux density heat shock, and under the condition of high heat flux density heating, the structure shell may be ablated and damaged due to untimely starting. SUMMARY

[0004] The technical problem solved by the present application is to overcome the shortcomings of the prior art, and to propose a composite guiding type non-ablation heat protection structure and a preparation method thereof, which can start in time and adapt to different aerodynamic heating environments, and improve the non-ablation heat protection capability of the heat protection system of the high-speed vehicle.

[0005] The technical solution of the present application is: a composite guiding type non-ablation heat protection structure, which comprises a heat protection structure body, a pulsating heat pipe flow channel, a heat pipe channel and a capillary structure; the heat protection structure body is the outermost layer; the pulsating heat pipe flow channel and the heat pipe channel are arranged in the inner side wall of the heat protection structure body in a staggered manner to form a guiding layer; the capillary structure is located in the inner side wall of the guiding layer, and the closed space surrounded by the capillary structure is a steam flow cavity;

[0006] The pulsating heat pipe flow channel is a closed pipe connected at the head and tail, and after the heat protection structure shell is heated, the working medium in the pulsating heat pipe flow channel circulates in the pulsating heat pipe to transport the local heating heat flow to the entire pulsating heat pipe area, thereby improving the equivalent thermal conductivity of the pulsating heat pipe area;

[0007] The heat pipe channel is a working medium transport channel of the steam chamber heat pipe; the capillary structure is used for condensation, adsorption and backflow of the working medium steam; the steam flow cavity is a flow space of the gaseous working medium in the steam chamber heat pipe; the steam chamber heat pipe is composed of the heat pipe channel, the capillary structure and the steam flow cavity; the steam chamber heat pipe starts under the heating of the pulsating heat pipe flow channel, phase change evaporation of the working medium, steam flow and steam condensation occur in different regions of the steam flow cavity, in the working medium condensation region, the gaseous working medium condenses in the capillary structure, the condensed working medium is transported from the working medium condensation region to the working medium phase change evaporation region through the heat pipe channel under the joint action of the capillary force and the gas pressure, and after being transported to the working medium phase change evaporation region, the working medium is phase changed into the gaseous working medium, and the cycle is repeated, so that the heat flow input by the pulsating heat pipe flow channel is dissipated in the form of full surface area radiation heat dissipation and reaches the equilibrium state.

[0008] Preferably, the pulsating heat pipe flow channel is distributed along a route as long as possible to uniformly cover the inner surface of the heat protection structure.

[0009] Preferably, the heat protection structure shell is made of copper-based alloy, iron-based alloy, nickel-based superalloy, niobium-based superalloy, molybdenum-based superalloy, tantalum-based superalloy, tungsten-based superalloy, C / C composite material, C / SiC composite material, SiC / SiC composite material or ultra-high temperature ceramic composite material.

[0010] Preferably, the pulsating heat pipe flow is circular, rectangular, "D" shaped or "Ω" shaped.

[0011] Preferably, the working medium in the pulsating heat pipe flow channel is heat conducting oil, molten salt, alkali metal, alkaline earth metal, base metal, heavy metal, noble metal or rare metal.

[0012] Preferably, the interface of the heat pipe channel is circular, rectangular, "D" shaped or "Ω" shaped.

[0013] Preferably, the capillary structure material is copper-based alloy, iron-based alloy, nickel-based superalloy, niobium-based superalloy, molybdenum-based superalloy, tantalum-based superalloy, tungsten-based superalloy, C / C composite material, C / SiC composite material, SiC / SiC composite material or ultra-high temperature ceramic composite material.

[0014] Preferably, the capillary structure has a maximum pore size of not greater than 0.2 mm and a porosity of not less than 30%.

[0015] Preferably, the steam flow cavity is in a vacuum state in the non-working state, and the vacuum degree is better than 10 -4 Pa.

[0016] Preferably, the heat protection structure shell, the pulsating heat pipe flow channel, the heat pipe channel and the capillary structure are integrally formed by an additive manufacturing method.

[0017] Another technical solution of the present application is a preparation method of a composite dredging type non-ablation heat protection structure, which comprises the following steps:

[0018] An integrally formed method of additive manufacturing is adopted to integrally form the heat protection structure shell, the pulsating heat pipe flow channel, the heat pipe channel and the capillary structure.

[0019] A vacuum pump is used to perform vacuumizing operation on the steam flow cavities formed by the pulsating heat pipe flow channel and the capillary structure, so that the internal absolute pressure reaches 1e -4 Pa or below.

[0020] The heat transfer working medium is injected into the steam flow cavities formed by the pulsating heat pipe flow channel and the capillary structure, and the sealing process is completed.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The present application is designed according to the respective advantages of the pulsating heat pipe and the steam cavity heat pipe, which not only utilizes the rapid start-up characteristics of the pulsating heat pipe to accelerate the start-up process of the overall dredging structure, but also utilizes the high heat transfer power characteristics of the steam cavity heat pipe to improve the limit heat transfer capacity of the overall dredging structure, thereby realizing the collaborative improvement of the start-up capacity and the heat transfer capacity of the heat pipe type dredging heat protection structure, especially effectively improving the heat protection adaptability of the overall dredging structure under high heat flux density heat shock load conditions through the rapid start-up performance of the dredging structure, thereby improving the non-ablation heat protection capacity of the aerospace high-speed vehicle heat protection system. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The present application is a pulsating composite heat pipe type high temperature dredging heat protection structure.

[0024] Figure 2 The present application is a pulsating composite heat pipe type high temperature dredging heat protection structure wall surface local enlargement structure.

[0025] Figure 3 The present application is a circular cross section pulsating composite heat pipe type high temperature dredging heat protection structure. DETAILED DESCRIPTION

[0026] The present application will be further described below in combination with embodiments.

[0027] For example, Figure 1As shown, the present application provides a composite heat dissipation structure, which comprises a heat protection structure 1, a pulsating heat pipe flow channel 2, a heat pipe channel 3, and a capillary structure 4. The heat protection structure 1 is the outermost layer. The pulsating heat pipe flow channel 2 and the heat pipe channel 3 are arranged alternately on the inner wall of the heat protection structure 1 to form a heat dissipation layer. The capillary structure 4 is located on the inner wall of the heat dissipation layer, and the closed space surrounded by the capillary structure 4 is a steam flow cavity 5. The composite heat dissipation structure is composed of Figure 1 As shown.

[0028] The pulsating heat pipe flow channel 2 is a closed pipe connected at both ends. After the heat protection structure shell 1 is heated, the working medium in the pulsating heat pipe flow channel 2 flows in the pulsating heat pipe and at the same time transports heat to the flowing area.

[0029] The heat pipe channel 3 is a working medium transport channel of the steam cavity heat pipe. The capillary structure 4 is used for condensation, adsorption and reflux of the working medium steam. The steam flow cavity 5 is a flow space for gaseous working medium in the steam cavity heat pipe. The heat pipe channel 3, the capillary structure 4 and the steam flow cavity 5 constitute the steam cavity heat pipe. The steam cavity heat pipe starts under the heating of the pulsating heat pipe flow channel 2. Phase change of working medium evaporation, steam flow and steam condensation occur in different areas of the steam flow cavity 5. In the working medium condensation area, the gaseous working medium condenses in the capillary structure 4. The condensed working medium is transported from the working medium condensation area to the working medium phase change area through the heat pipe channel 3 under the joint action of capillary force and gas pressure. After being transported to the working medium phase change area, the working medium evaporates into gaseous working medium, and the cycle is repeated. The heat flow input by the pulsating heat pipe flow channel 2 is dissipated in the form of full surface area radiation heat dissipation and reaches an equilibrium state.

[0030] Preferably, the pulsating heat pipe flow channel distribution route 6 is evenly distributed on the inner surface of the heat protection structure 1 in the longest path.

[0031] Preferably, the heat protection structure shell 1 can be made of various high-temperature-resistant materials, such as copper-based alloy, iron-based alloy, nickel-based high-temperature alloy, niobium-based high-temperature alloy, molybdenum-based high-temperature alloy, C / C composite material, C / SiC composite material, SiC / SiC composite material or ultra-high-temperature ceramic composite material UHTCs.

[0032] Preferably, the pulsating heat pipe flow channel 2 is a working medium flow channel of a high-temperature pulsating heat pipe, which is composed of working medium and vacuum area in the flow channel. The cross section of the pulsating heat pipe flow channel 2 can be designed according to wall constraints and flow characteristics, which can be circular, rectangular, "D" shaped or "Ω" shaped. Figure 2 The schematic diagram shows a "D" shaped flow channel.

[0033] Preferably, the working fluid in the pulsating heat pipe flow channel 2 can be appropriately selected according to the service temperature of the heat dissipation structure, and the temperature can be selected from high to low, which can be a heat conducting material, a molten salt, an alkali metal, an alkaline earth metal, a base metal, a heavy metal, a noble metal, or a rare metal.

[0034] Preferably, the cross section of the heat pipe channel 3 mainly considers factors such as improving the adsorption capillary force of the working fluid and reducing the flow resistance of the working fluid returning to the heating section, and can be circular, rectangular, "D" shaped or "Ω" shaped. Figure 2 The schematic diagram is a "Ω" shaped channel. In order to ensure good capillary force, the maximum geometric size of the channel is generally less than 0.5mm.

[0035] Preferably, the capillary structure 4 is a capillary structure designed to improve the condensation, adsorption and return of the working fluid vapor in the vapor chamber heat pipe, and the capillary structure material can be copper-based alloy, iron-based alloy, nickel-based superalloy, niobium-based superalloy, molybdenum-based superalloy, tantalum-based superalloy, tungsten-based superalloy, C / C composite material, C / SiC composite material, SiC / SiC composite material or ultra-high temperature ceramic composite material.

[0036] Preferably, the maximum void size of the capillary structure 4 is not greater than 0.2mm, and the porosity is not less than 30%. The forming process of the capillary structure 4 can be porous body sintering, different mesh screen layering, microstructure additive manufacturing, mold CVD or PVD deposition, etc.

[0037] The steam flow cavity 5 is the flow space of the gaseous working fluid in the vapor chamber heat pipe. Before starting, the steam flow cavity 5 is in a vacuum state, and the vacuum degree is generally better than 10 -4 Pa; due to the uneven heating of the heat dissipation structure shell 1, there are working fluid evaporation zones and working fluid condensation zones in different areas of the steam flow cavity 5. The capillary structure 4 improves the adsorption capacity of the gaseous working fluid in the condensation zone to condense into liquid working fluid, and the heat pipe channel 3 improves the transport capacity of the liquid working fluid from the condensation zone to the evaporation zone.

[0038] Preferably, the heat dissipation structure shell 1, the pulsating heat pipe flow channel 2, the heat pipe channel 3 and the capillary structure 4 can be integrally formed by additive manufacturing technology after unified modeling, such as laser selective melting forming SLM, electron beam selective melting forming EBSM, precursor thermal / light curing-sintering forming, etc.; or can be manufactured in parts, and assembled by mechanical fitting connection or welding process.

[0039] The detailed structure and positional relationship of the heat dissipation structure shell 1, the pulsating heat pipe flow channel 2, the heat pipe channel 3 and the capillary structure 4 are shown in the partial enlarged structure of the pulsating composite heat pipe type high temperature heat dissipation structure wall surface. Figure 2

[0040] ​The above pulsating composite heat pipe type high-temperature heat dissipation and heat protection structure section can be designed according to actual needs, and can be a square (square) section, a circular section or other special-shaped sections. Figure 3 A pulsating composite heat pipe type high-temperature heat dissipation and heat protection structure with a circular section is shown in the schematic diagram.

[0041] The overall working process of the above composite heat dissipation type non-ablation heat protection structure is as follows: the heat protection structure shell 1 is fully or partially subjected to heating, and the working medium in the pulsating heat pipe 2 starts to flow in the pipe and simultaneously transports heat to the flowing area; the steam cavity heat pipe starts to start under the heating of the pulsating heat pipe flow channel, and the evaporation phase change of the working medium, steam flow and steam condensation occur in different areas of the steam flow cavity 5; the gaseous working medium condenses in the enhanced adsorption capacity capillary structure 4 in the lower temperature area, and the condensed working medium is transported from the working medium condensation area (lower temperature area) to the working medium evaporation phase change area (higher temperature area) by the capillary force and gas pressure; the cycle is repeated until the composite pulsating / steam cavity heat pipe type high-temperature heat dissipation and heat protection structure forms an approximately isothermal body, the input heat flow is dissipated in the form of full surface area radiation heat dissipation and reaches an equilibrium state, and the system reaches a stable working state.

[0042] The preparation method of the above composite heat dissipation type non-ablation heat protection structure comprises the following steps:

[0043] Step S1, the heat protection structure shell 1, the pulsating heat pipe flow channel 2, the heat pipe channel 3 and the capillary structure 4 are integrally formed by using an additive manufacturing integrated forming method; specifically, the additive manufacturing technology can be selected from laser selective melting forming SLM, electron beam selective melting forming EBSM, precursor thermal / light curing-sintering forming and the like. The heat protection structure shell 1, the pulsating heat pipe flow channel 2, the heat pipe channel 3 and the capillary structure 4 can also be manufactured separately, and then assembled by using mechanical fitting connection or welding process.

[0044] Step S2, a vacuum pump is used to perform vacuumizing operation on the steam flow cavity 5 formed by the pulsating heat pipe flow channel 2 and the capillary structure 4, so that the internal absolute pressure reaches 1e -4 Pa or below.

[0045] Step S3, the heat transfer working medium is injected into the steam flow cavity 5 formed by the pulsating heat pipe flow channel 2 and the capillary structure 4, and the sealing process is completed.

[0046] Embodiment 1:

[0047] In a specific embodiment of the present application, a rectangular section pulsating composite heat pipe type high-temperature heat dissipation and heat protection structure is designed and prepared, and the structure is the same as Figure 1As shown, in the embodiment, the overall composition of the rectangular cross-section pulsating composite heat pipe type high-temperature heat dissipation and heat protection structure includes: a heat protection structure shell 1, a pulsating heat pipe flow channel 2, a heat pipe channel 3, and a capillary structure 4. The middle space of the capillary structure 4 forms a steam flow cavity 5. The overall flow channel form 6 of the pulsating heat pipe flow channel 2 is designed as a continuous and zigzag path to improve the coverage of the entire heat protection structure shell 1.

[0048] The heat protection structure shell 1 is made of nickel-based high-temperature alloy with a material grade of GH4169.

[0049] The working medium flow channel 2 of the high-temperature pulsating heat pipe is designed as a "D" shaped flow channel, wherein the diameter of the "D" shaped flow channel is 6 mm, and the column segment height is 2 mm.

[0050] The working medium of the pulsating heat pipe flow channel 2 is NaK alloy with a mass ratio of 0.5:0.5; the working medium is filled in a vacuum environment, and the vacuum degree is controlled to be better than 10 -4 Pa.

[0051] The heat pipe channel 3 is designed as an "Ω" shaped channel, wherein the diameter of the "Ω" shaped flow channel is 0.4 mm, and the column segment height is 0.2 mm.

[0052] The capillary structure 4 is made of SLM laser forming three-dimensional lattice structure, the material is nickel-based high-temperature alloy with a grade of GH4169, the lattice structure unit cell is simple cubic (SC) + body-centered structure (BCC), the lattice constant is 0.7 mm, and the lattice connecting rod diameter is 0.2 mm.

[0053] After the heat protection structure shell 1, the pulsating heat pipe flow channel 2, the heat pipe channel 3, and the capillary structure 4 are uniformly modeled, the main body and the sealing cover plate structure are integrally formed by using SLM additive self-manufacturing technology, and the main body and the sealing cover plate are formed by electron beam welding.

[0054] K working medium is selected in the steam flow cavity 5; the working medium is filled in a vacuum environment, and the vacuum degree is controlled to be better than 10 - 4 Pa.

[0055] Under the action of a 100kW induction heating heat source, test results show that, compared with the traditional nickel-based high-temperature alloy-sodium working medium steam cavity heat pipe type high-temperature heat dissipation and heat protection structure, the complete starting time of the heat protection structure is improved from 30s to 10s.

[0056] Embodiment 2:

[0057] In a specific embodiment of the present application, a circular cross-section pulsating composite heat pipe type high-temperature heat dissipation and heat protection structure is designed and prepared, and the structure is the same as Figure 1As shown, in the embodiment, the circular cross-section pulsating composite heat pipe type high-temperature heat dissipation structure is composed of a heat dissipation structure shell 1, a pulsating heat pipe flow channel 2, a heat pipe channel 3, and a capillary structure 4. The middle space of the capillary structure 4 forms a steam flow cavity 5. The overall flow channel form 6 of the pulsating heat pipe flow channel 2 is designed as a continuous and zigzag path to improve the coverage of the entire heat dissipation structure shell 1.

[0058] The heat dissipation structure shell 1 is made of a nickel-based high-temperature alloy with a material grade of GH4169.

[0059] The working medium flow channel 2 of the high-temperature pulsating heat pipe is designed as a "D" shaped flow channel, wherein the diameter of the "D" shaped flow channel is 6 mm, and the column segment height is 2 mm.

[0060] The working medium of the pulsating heat pipe flow channel 2 is selected as NaK alloy with a mass ratio of 0.5:0.5. The working medium is filled in a vacuum environment, and the vacuum degree is controlled to be better than 10 -4 Pa.

[0061] The heat pipe channel 3 is designed as an "Ω" shaped channel, wherein the diameter of the "Ω" shaped flow channel is 0.4 mm, and the column segment height is 0.2 mm.

[0062] The capillary structure 4 is made of a SLM laser formed three-dimensional lattice structure, the material is a nickel-based high-temperature alloy with a grade of GH4169, the lattice structure unit cell is a simple cubic (SC) + body-centered structure (BCC), the lattice constant is 0.7 mm, and the lattice connecting rod diameter is 0.2 mm.

[0063] After the heat dissipation structure shell 1, the pulsating heat pipe flow channel 2, the heat pipe channel 3, and the capillary structure 4 are uniformly modeled, the main body and the sealing cover plate structure are integrally formed by using SLM additive self-manufacturing technology, and the main body and the sealing cover plate are formed by electron beam welding.

[0064] K working medium is selected in the steam flow cavity 5. The working medium is filled in a vacuum environment, and the vacuum degree is controlled to be better than 10 - 4 Pa. Although the present application has been disclosed with reference to the preferred embodiments above, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A composite, channeled, non-ablativ e thermal protection structure, characterized in that The heat protection structure (1), the pulsating heat pipe flow channel (2), the heat pipe channel (3), and the capillary structure (4); the heat protection structure (1) is the outermost layer; the pulsating heat pipe flow channel (2) and the heat pipe channel (3) are staggered arranged on the inner wall of the heat protection structure (1) to form a heat dissipation layer; the capillary structure (4) is located on the inner wall of the heat dissipation layer, and the closed space surrounded by the capillary structure (4) is a steam flow cavity (5); The pulsating heat pipe flow channel (2) is a closed pipeline connected at the head and tail, and after the heat protection structure (1) is heated, the working medium in the pulsating heat pipe flow channel (2) circulates in the pulsating heat pipe; The heat pipe channel (3) is a working medium transport channel of the steam cavity heat pipe; the capillary structure (4) is used for condensation, adsorption and reflux of the working medium steam; the steam flow cavity (5) is a flow space of the gaseous working medium in the steam cavity heat pipe; the heat pipe channel (3), the capillary structure (4) and the steam flow cavity (5) constitute the steam cavity heat pipe.

2. The composite flow-restricted non-ablative thermal protection structure according to claim 1, characterized in that The distribution route of the pulsating heat pipe flow channel is evenly distributed on the inner surface of the heat protection structure (1) as long as possible.

3. The composite flow-restricted non-ablative thermal protection structure according to claim 1, characterized in that The heat protection structure (1) is made of copper-based alloy, iron-based alloy, nickel-based high-temperature alloy, niobium-based high-temperature alloy, molybdenum-based high-temperature alloy, C / C composite material, C / SiC composite material, SiC / SiC composite material or super high-temperature ceramic composite material.

4. The composite flow-restricted non-ablative thermal protection structure according to claim 1, characterized in that The pulsating heat pipe flow channel (2) is circular, rectangular, "D" shaped or "Ω" shaped.

5. The composite flow-restricted non-ablative thermal protection structure according to claim 1, characterized in that The working medium in the pulsating heat pipe flow channel (2) is heat conducting um, molten salt, alkali metal, alkaline earth metal, base metal, heavy metal, noble metal or rare metal.

6. The composite flow-restricted non-ablativ e thermal protection structure according to claim 1, characterized in that The interface of the heat pipe channel (3) is circular, rectangular, "D" shaped or "Ω" shaped.

7. The composite flow-restricted non-ablativ e thermal protection structure according to claim 1, characterized in that The capillary structure material is copper-based alloy, iron-based alloy, nickel-based high-temperature alloy, niobium-based high-temperature alloy, molybdenum-based high-temperature alloy, tantalum-based high-temperature alloy, tungsten-based high-temperature alloy, C / C composite material, C / SiC composite material, SiC / SiC composite material or super high-temperature ceramic composite material.

8. The composite flow-restricted non-ablativ e thermal protection structure according to claim 7, characterized in that The maximum pore size of the capillary structure (4) is not greater than 0.2 mm, and the porosity is not less than 30%.

9. The composite, flow-restricted, non- ablative thermal protection structure of claim 8, wherein The steam flow cavity (5) is in vacuum state in non-working state, and the vacuum degree is better than 10 -4 Pa.

10. The method of making a composite heat shield structure according to claim 1, wherein The method comprises the following steps: The heat protection structure (1), the pulsating heat pipe flow channel (2), the heat pipe channel (3) and the capillary structure (4) are integrally formed by using an additive manufacturing method; The vacuum pump is used to vacuumize the pulsating heat pipe flow channel (2) and the steam flow cavity (5) formed by the capillary structure (4) respectively, so that the internal absolute pressure reaches 10 -4 Pa below; The heat transfer working medium is injected into the steam flow cavity (5) formed by the pulsating heat pipe flow channel (2) and the capillary structure (4), and a sealing process is completed.

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