A multi-layer sweating cooling flame tube and its implementation method

Abstract

This application relates to a multi-layer sweating cooling flame tube and its implementation method. The multi-layer sweating cooling flame tube includes: a macroscopic guiding porous layer, a microscopic capillary porous layer, and a nanoporous coating layer stacked sequentially. The macroscopic guiding porous layer is configured to receive cooling air, and the nanoporous coating layer is configured to face the high-temperature combustion gas. The average pore size of the microscopic capillary porous layer is smaller than that of the macroscopic guiding porous layer, and the average pore size of the nanoporous coating layer is smaller than that of the microscopic capillary porous layer. The multi-layer sweating cooling flame tube, with its hierarchical porous structure, can spontaneously draw cooling air from the macroscopic guiding porous layer to the microscopic capillary porous layer using capillary action, and ultimately allow the air to permeate uniformly through the nanoporous coating layer, thereby forming a continuous, stable, and fully covering cooling gas film on the high-temperature combustion gas side, isolating the high-temperature combustion gas.

Description

Technical Field

[0001] This application relates to the field of engine technology, and in particular to a multi-layer sweating cooling flame tube and its implementation method. Background Technology

[0002] As aero engines continue to develop towards higher thrust-to-weight ratios and higher cycle parameters, the combustion chamber needs to organize combustion at higher inlet temperatures and pressures. This leads to a sharp increase in the thermal load on the flame tube, the core high-temperature component of the combustion chamber. At the same time, in pursuit of higher thermal efficiency, more air is allocated to the combustion zone, resulting in a relatively reduced share of air available for cooling the flame tube. This places unprecedentedly stringent requirements on the cooling technology of the flame tube.

[0003] In related technologies, existing aero-engines use film cooling technology for non-flame tubes. This technology typically involves opening a large number of discrete exhaust holes or gaps on the flame tube wall to spray streams of cooling air from the compressor onto the inner wall surface of the flame tube in the form of jets. This forms a layer of low-temperature gas film on the inner wall surface of the flame tube, which is used to isolate the high-temperature combustion gas and facilitate convective heat transfer to the wall surface.

[0004] However, after leaving the film cooling orifice, the scattered flow will be violently mixed and entrained with the high-speed mainstream combustion gas, and is very easy to be lifted off the wall, resulting in discontinuous and unstable cooling film coverage, forming local "hot spots" in the inter-orifice area, and causing low cooling efficiency. Summary of the Invention

[0005] Therefore, it is necessary to provide a multi-layer sweating cooling flame tube and its implementation method to address the problem that existing methods of opening exhaust holes or gaps on the flame tube wall result in discontinuous and unstable cooling gas film coverage.

[0006] This application provides a multi-layer sweating cooling flame tube, the multi-layer sweating cooling flame tube comprising:

[0007] A macroscopic flow-guiding porous layer, a microscopic capillary porous layer, and a nanoporous coating are stacked sequentially, wherein the macroscopic flow-guiding porous layer is configured to receive cooling air, and the nanoporous coating is configured to face high-temperature combustion gas.

[0008] The average pore size of the micro-capillary porous layer is smaller than that of the macro-fluidic porous layer, and the average pore size of the nanoporous coating is smaller than that of the micro-capillary porous layer.

[0009] In one embodiment, the macroscopic flow-guiding porous layer is provided with graded flow-guiding channels.

[0010] In one embodiment, the equivalent diameter of the flow channel is 0.5mm-2mm.

[0011] In one embodiment, the flow channel is biomimetic in the shape of a tree or leaf vein.

[0012] In one embodiment, at least one structural parameter of the macroscopic flow-guiding porous layer varies with a gradient along the axial and / or circumferential direction of the flame tube.

[0013] The structural parameters include the equivalent diameter of the flow channel and the local porosity of the macroscopic flow-guiding porous layer.

[0014] In one embodiment, the thickness of the macroscopic flow-guiding porous layer accounts for 50%-80% of the total thickness of the flame tube, wherein the total thickness of the flame tube is the sum of the thicknesses of the macroscopic flow-guiding porous layer, the microscopic capillary porous layer, and the nanoporous coating.

[0015] In one embodiment, the thickness of the micro-capillary porous layer is 0.5 mm-3 mm; and / or,

[0016] The average pore size of the micro-capillary porous layer is 10μm-100μm; and / or,

[0017] The porosity of the micro-capillary porous layer is 30%-70%.

[0018] In one embodiment, the thickness of the nanoporous coating is 0.5 μm-200 μm; and / or,

[0019] The surface of the nanoporous coating has a nanoscale rough structure; and / or,

[0020] The average pore size of the nanoporous coating is less than 1 μm.

[0021] This application also provides a method for implementing a multi-layer sweating cooling flame tube, used to prepare the multi-layer sweating cooling flame tube described in any of the above claims, the method comprising:

[0022] The process forms a macroscopic flow-guiding porous layer and a microscopic capillary porous layer, and the processing makes the average pore size of the microscopic capillary porous layer smaller than the average pore size of the macroscopic flow-guiding porous layer.

[0023] A nanoporous coating is prepared on the surface of the microcapillary porous layer exposed to the high-temperature gas combustion side, and the coating is processed such that the average pore size of the nanoporous coating is smaller than the average pore size of the microcapillary porous layer.

[0024] In one embodiment, the macroscopic flow-guiding porous layer and the microscopic capillary porous layer are formed by integrated processing using selective laser melting metal additive manufacturing technology, and the microscopic capillary porous layer is formed by adjusting the laser process parameters to an incompletely melted state.

[0025] The aforementioned multi-layered sweating cooling flame tube, by sequentially stacking a macroscopic guiding porous layer, a microscopic capillary porous layer, and a nanoporous coating, and limiting the average pore size of the microscopic capillary porous layer to be smaller than that of the macroscopic guiding porous layer, and the average pore size of the nanoporous coating to be smaller than that of the microscopic capillary porous layer, constitutes a hierarchical porous structure. This hierarchical porous structure can spontaneously draw cooling air from the macroscopic guiding porous layer to the microscopic capillary porous layer using capillary action, and ultimately allow the air to permeate uniformly through the nanoporous coating, thereby forming a continuous, stable, and comprehensively covering cooling gas film on the high-temperature combustion gas side, isolating the high-temperature combustion gas. The multi-layered sweating cooling flame tube of this application solves the problems of uneven coverage and the easy formation of local hot spots in traditional discrete gas film cooling. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the flame tube provided in an embodiment of this application.

[0027] Figure 2 This is a schematic diagram showing the structure of the macroscopic flow-guiding porous layer, the microscopic capillary porous layer, and the nanoporous coating arranged in sequence, as provided in the embodiments of this application.

[0028] Figure 3 This is a schematic diagram of the structure of the macroscopic flow-guiding porous layer provided in the embodiments of this application.

[0029] Figure 4 This is a schematic diagram of the structure of the micro-capillary porous layer provided in the embodiments of this application.

[0030] Figure 5 This is a schematic diagram of the structure of the nanoporous coating provided in the embodiments of this application.

[0031] Figure label:

[0032] 100. Multi-layered sweating cooling flame tube;

[0033] 200. Macroscopic flow-guiding porous layer;

[0034] 300. Microscopic capillary porous layer;

[0035] 400, nanoporous coating. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0037] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0038] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0042] This application provides a multi-layer sweating cooling flame tube 100, such as Figures 1 to 5 As shown, the multi-layer sweating cooling flame tube 100 includes:

[0043] The macroscopic flow-guiding porous layer 200, the microscopic capillary porous layer 300, and the nanoporous coating 400 are stacked in sequence. The macroscopic flow-guiding porous layer 200 is configured to receive cooling air, and the nanoporous coating 400 is configured to face the high-temperature combustion gas.

[0044] The average pore size of the micro-capillary porous layer 300 is smaller than that of the macro-flow-conducting porous layer 200, and the average pore size of the nano-porous coating 400 is smaller than that of the micro-capillary porous layer 300.

[0045] The aforementioned multi-layer sweating cooling flame tube 100, by sequentially stacking a macroscopic guiding porous layer 200, a microscopic capillary porous layer 300, and a nanoporous coating 400, and defining that the average pore size of the microscopic capillary porous layer 300 is smaller than that of the macroscopic guiding porous layer 200, and the average pore size of the nanoporous coating 400 is smaller than that of the microscopic capillary porous layer 300, thus forming a hierarchical porous structure. This hierarchical porous structure can spontaneously draw cooling air from the macroscopic guiding porous layer 200 to the microscopic capillary porous layer 300 using capillary action, and ultimately allow the air to uniformly permeate through the nanoporous coating 400, thereby forming a continuous, stable, and fully covered cooling gas film on the high-temperature combustion gas side, isolating the high-temperature combustion gas. The multi-layer sweating cooling flame tube 100 of this application solves the problems of uneven coverage and easy formation of local hot spots in traditional discrete gas film cooling.

[0046] It should be noted that the average pore size refers to the statistical average value of the pore or channel pore size inside the porous structure.

[0047] In one embodiment, the macroscopic flow-guiding porous layer 200 is provided with graded flow-guiding channels. By providing graded flow-guiding channels on the macroscopic flow-guiding porous layer 200, a structured low-flow-resistance distribution network is established for the cooling air. This network can transport the cooling air to various areas of the flame tube 100 wall, providing a stable and evenly distributed air source basis for subsequent capillary suction and uniform seepage.

[0048] It should be noted that the term "hierarchical arrangement" or "hierarchical" is used to describe the flow channel structure in the macroscopic flow-guiding porous layer. Specifically, it refers to the multi-level, non-uniform distribution of the channel system in its topology. This structure manifests as follows: a relatively small number of primary channels (main channels) with large flow cross-sections receive the incoming flow from the cooling air inlet; these primary channels then branch or fork to connect to a larger number of secondary channels with relatively smaller flow cross-sections; depending on actual needs, the secondary channels can further branch to form finer tertiary or more levels of channels, ultimately forming a channel network with parent-child hierarchical relationships covering the entire macroscopic flow-guiding porous layer region.

[0049] In this embodiment, the flow channel is biomimetic tree-like or leaf-vein-like. By setting the flow channel as a biomimetic tree-like or leaf-vein-like structure, the fractal characteristics of efficient fluid transport systems in nature are simulated; the biomimetic tree-like or leaf-vein-like structure can achieve optimized distribution of cooling air from the centralized injection point to the entire wall coverage area with fewer flow paths and lower flow resistance.

[0050] In other embodiments, the flow channel may also be a topological configuration that enables fluid distribution and transport, such as a mesh structure or a radial branch structure.

[0051] In one embodiment, the equivalent diameter of the flow guiding channel is 0.5mm-2mm. Limiting the equivalent diameter of the flow guiding channel to the range of 0.5mm-2mm ensures sufficient mechanical strength and structural stability of the macroscopic flow guiding porous layer 200 while maintaining cooling airflow capacity and low flow resistance. This avoids the problems of structural weakening due to excessively large channels or increased flow resistance due to excessively small channels.

[0052] It should be noted that the equivalent diameter, also known as the hydraulic diameter in this field, is a key parameter used to characterize the geometry of a non-circular cross-section flow channel. It is defined as the ratio of four times the channel's cross-sectional area to its wetted perimeter.

[0053] In one embodiment, at least one structural parameter of the macroscopic flow-guiding porous layer 200 varies with a gradient along the axial and / or circumferential direction of the flame tube 100; wherein, the structural parameter includes the equivalent diameter of the flow-guiding channel and the local porosity of the macroscopic flow-guiding porous layer 200. By varying the structural parameters (equivalent diameter of the flow-guiding channel and / or local porosity) of the macroscopic flow-guiding porous layer 200 with a gradient along the axial and / or circumferential direction of the flame tube 100, the supply of cooling air can be matched with the heat load distribution of different regions of the wall; specifically, in regions with higher heat loads, more cooling air is automatically allocated by increasing the channel diameter or increasing the porosity, realizing "on-demand allocation" of cooling resources.

[0054] It should be noted that local porosity is a key parameter used to characterize the degree of porosity in a specific local region (not the overall average) of the macroscopic flow-guiding porous layer. It is defined as the ratio of the pore volume (including the volume of flow channels and other micropores) to the total volume of a specific local region within the macroscopic flow-guiding porous layer.

[0055] The aforementioned localized areas can be divided according to the heat load distribution on the flame tube wall, typically corresponding to regions with different heat load levels. By designing different porosities in different localized areas, thus creating a porosity gradient distribution, it is possible to achieve on-demand distribution of cooling gas flow. In areas with higher heat loads, a higher local porosity is used to provide a larger cooling gas flux, while in areas with lower heat loads, a lower local porosity is used to reduce the cooling gas flow.

[0056] In one embodiment, the thickness of the macroscopic flow-guiding porous layer 200 accounts for 50%-80% of the total thickness of the flame tube 100, wherein the total thickness of the flame tube 100 is the sum of the thicknesses of the macroscopic flow-guiding porous layer 200, the microscopic capillary porous layer 300, and the nanoporous coating 400. By limiting the thickness of the macroscopic flow-guiding porous layer 200 to 50%-80% of the total thickness of the flame tube 100, it is ensured that the macroscopic flow-guiding porous layer 200 occupies a dominant position in the overall structure, has sufficient space to accommodate and arrange the flow channels, and provides sufficient gas distribution capacity for the entire cooling system. At the same time, it ensures that the microscopic capillary porous layer 300 and the nanoporous coating 400 have reasonable thickness space to realize their capillary suction and stable exudation functions.

[0057] In one embodiment, the thickness of the microcapillary porous layer 300 is 0.5 mm to 3 mm; and / or, the average pore size of the microcapillary porous layer 300 is 10 μm to 100 μm; and / or, the porosity of the microcapillary porous layer 300 is 30% to 70%. By limiting the thickness, average pore size, and porosity of the microcapillary porous layer 300 to the ranges of 0.5 mm to 3 mm, 10 μm to 100 μm, and 30% to 70%, respectively, it is ensured that the microcapillary porous layer 300 can generate sufficiently strong capillary force to actively draw cooling air from the macroscopic flow-guiding porous layer 200. Moreover, the microcapillary porous layer 300 itself possesses suitable pore space and permeability, which can both store and transport sufficient cooling medium and ensure that air is uniformly transported to the nanoporous coating 400.

[0058] In one embodiment, the thickness of the nanoporous coating 400 is 0.5 μm-200 μm; and / or, the surface of the nanoporous coating 400 has a nanoscale rough structure; and / or, the average pore size of the nanoporous coating 400 is less than 1 μm. By limiting the thickness of the nanoporous coating 400 to 0.5 μm-200 μm and controlling the average pore size of the nanoporous coating 400 to a nanoscale of less than 1 μm, or by giving the surface of the nanoporous coating 400 a nanoscale rough structure, the stability of the permeated gas film in the high-speed gas flow is enhanced; at the same time, the convective heat transfer intensity between the gas film and the wall surface is enhanced, thereby forming a thermal insulation cooling barrier on the hot side.

[0059] In summary, compared with existing technologies, the multi-layer sweating cooling flame tube 100 of this application, with its graded porous structure and adaptive air film cooling scheme, demonstrates superior comprehensive benefits. Its core advantage lies in achieving a qualitative leap in cooling efficiency through the synergistic effect of macroscopic flow guidance, capillary transport, and nanoscale stabilization. Specifically, this structure not only inherits the advantages of uniform coverage in traditional sweating cooling but also achieves "on-demand distribution" of cooling air according to the wall's heat load through a unique gradient pore design. This means it automatically provides stronger cooling in high-temperature regions, fundamentally solving the problem of uneven cooling in homogeneous porous bodies. This significantly improves overall cooling efficiency and is expected to reduce total cooling air consumption while achieving the same or better cooling effect, allowing more air to participate in the main combustion process, directly benefiting the engine's thermal efficiency and thrust.

[0060] Furthermore, the nanoporous coating 400 located on the high-temperature combustion gas side, through its nanoscale surface structure, greatly enhances the stability of the permeated gas film in the high-speed combustion gas flow, forming a dense, fully covered heat insulation layer that is not easily blown away, further improving the heat insulation effect. The entire cooling process mainly relies on passive capillary force drive, requiring no complex external active control system. Its simple structure and high operational reliability make it extremely suitable for long-term operation in harsh engine environments with high temperatures and high vibrations. This passive reliability, combined with efficient and uniform cooling capacity, significantly reduces the local peak temperature and thermal stress of the flame tube 100, effectively suppressing the initiation and propagation of thermal fatigue cracks, thereby greatly extending the service life of the flame tube 100.

[0061] Furthermore, compared to traditional single-pore sweating cooling structures, the hierarchical porous structure of this application has an inherent advantage in anti-clogging performance. Its macroscopic flow guide layer can pre-distribute and filter airflow, while the gradient transition design of the micro and nano layers reduces the possibility of impurities accumulating at narrow pore throats, effectively reducing the risk of pore blockage due to carbon deposits or foreign matter, and improving the long-term operational reliability of the system.

[0062] It should be noted that, in addition to the combustion chamber flame tube 100 of an aero-engine, the gas film adaptive cooling scheme based on a graded porous structure provided in this application, with its passively driven, highly efficient and uniform, on-demand distribution, and ultra-stable full-coverage cooling characteristics, is also suitable for other environments facing extreme aerodynamic and thermal loads. For example, this cooling structure and method can be applied to the thermal protection system of hypersonic vehicles to provide efficient active cooling for key components such as sharp leading edges and control surfaces; it can also be used for the thrust chamber walls of rocket engines to cope with extremely high combustion temperatures and heat flux densities; and it can also be applied to the combustion chamber of scramjet engines to solve the severe thermal protection challenges brought about by prolonged high-temperature combustion.

[0063] This application also provides a method for implementing a multi-layer sweating cooling flame tube 100, used to prepare the multi-layer sweating cooling flame tube 100 according to any of the above claims, the method comprising:

[0064] The process forms a macroscopic flow-guiding porous layer 200 and a microscopic capillary porous layer 300, and the process makes the average pore size of the microscopic capillary porous layer 300 smaller than the average pore size of the macroscopic flow-guiding porous layer 200.

[0065] A nanoporous coating 400 is prepared on the surface of the micro-capillary porous layer 300 exposed to the high-temperature gas combustion side, and the processing is such that the average pore size of the nanoporous coating 400 is smaller than the average pore size of the micro-capillary porous layer 300.

[0066] The above-mentioned method for realizing the multi-layer sweating cooling flame tube 100 controls the formation of the macroscopic flow-guiding porous layer 200 and the microscopic capillary porous layer 300 during the processing, and makes the average pore size of the microscopic capillary porous layer 300 smaller than the average pore size of the macroscopic flow-guiding porous layer 200. At the same time, a nanoporous coating 400 with an even smaller average pore size is prepared on the microscopic capillary porous layer 300. This method directly ensures that the product has a pore size gradient, and ensures that the three-level porous structure can achieve smooth functional connection during the manufacturing process, providing a reliable process guarantee for finally obtaining a high-performance flame tube 100 with self-driving and adaptive cooling capabilities.

[0067] In one embodiment, the macroscopic flow-guiding porous layer 200 is integrally formed by selective laser melting metal additive manufacturing technology, and its manufacturing material is a nickel-based high-temperature alloy or a cobalt-based high-temperature alloy.

[0068] In one embodiment, a macroscopic flow-guiding porous layer 200 and a microscopic capillary porous layer 300 are integrally formed using selective laser melting (SLM) metal additive manufacturing technology. The microscopic capillary porous layer 300 is formed by controlling the laser process parameters to a partially melted state. By using SLM to integrally process the macroscopic flow-guiding porous layer 200 and the microscopic capillary porous layer 300, and controlling the laser process to form an incompletely melted powder-bonded structure in the microscopic capillary porous layer 300, a seamless transition and combination of the dense flow-guiding channels of the macroscopic flow-guiding porous layer 200 and the porous capillary structure of the microscopic capillary porous layer 300 is achieved in terms of material and morphology. The integral molding process not only avoids the interfacial thermal resistance and potential connection failure risks caused by the layered structure, but also enables precise and controllable fabrication of complex three-dimensional structures with specific pore size gradients, ensuring the consistency and reliability of the equipment.

[0069] In other embodiments, the micro-capillary porous layer 300 is prepared from a ceramic matrix composite material. By controlling the preform structure of the ceramic fiber braid and combining it with melt impregnation or chemical vapor impregnation processes, a gradient porosity is formed in the micro-capillary porous layer 300. By using a ceramic matrix composite material to prepare the micro-capillary porous layer 300 and utilizing the control of the preform structure of the ceramic fiber braid combined with melt impregnation or chemical vapor impregnation processes, a gradient porosity distribution is actively constructed within the micro-capillary porous layer 300. This allows the micro-capillary porous layer 300 to not only possess the inherent high-temperature resistance and corrosion resistance of ceramic materials, but also to achieve on-demand allocation of cooling gas flow rate by controlling the porosity according to the heat load distribution in different areas of the flame tube 100 wall. That is, more cooling gas is provided in areas with higher heat load through higher porosity, and the gas flow rate is reduced in areas with lower heat load through lower porosity.

[0070] In one embodiment, the nanoporous coating 400 is grown in situ on the substrate by anodizing or thermal oxidation, or is prepared as a porous ceramic layer by atmospheric plasma spraying or solution precursor plasma spraying processes; the material of the porous ceramic layer is yttrium-stabilized zirconium oxide, alumina, or rare earth acid salts.

[0071] By using anodic oxidation or thermal oxidation to grow a nanoporous coating 400 in situ on the substrate, a nanostructured surface with high bonding strength to the substrate and strong interfacial bonding can be formed, which enhances the coating's thermal shock resistance and service reliability. On the other hand, by preparing a porous ceramic layer through atmospheric plasma spraying or solution precursor plasma spraying, a nanoporous coating 400 with controllable thickness, uniform pore structure and thermal insulation properties can be obtained.

[0072] Yttrium-stabilized zirconia, alumina, or rare earth salts are selected as coating materials. By utilizing the characteristics of ceramic materials such as high melting point, low thermal conductivity, excellent high-temperature stability, and good corrosion resistance, the nanoporous coating 400 can maintain structural integrity and functionality under extreme high temperature and thermal shock environments, thereby improving the stability and durability of the cooling gas film.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A multi-layer sweating cooling flame tube, characterized in that, The multi-layer sweating cooling flame tube includes: A macroscopic flow-guiding porous layer (200), a microscopic capillary porous layer (300), and a nanoporous coating (400) are stacked sequentially, wherein the macroscopic flow-guiding porous layer (200) is configured to receive cooling air, and the nanoporous coating (400) is configured to face high-temperature combustion gas. The average pore size of the micro-capillary porous layer (300) is smaller than that of the macro-flow-guiding porous layer (200), and the average pore size of the nano-porous coating (400) is smaller than that of the micro-capillary porous layer (300). The macroscopic flow-guiding porous layer (200) is provided with graded flow-guiding channels; The flow channel is biomimetic in the shape of a tree or leaf vein.

2. The multi-layer sweating cooling flame tube according to claim 1, characterized in that, The equivalent diameter of the flow channel is 0.5mm-2mm.

3. The multi-layer sweating cooling flame tube according to claim 1, characterized in that, At least one structural parameter of the macroscopic flow-guiding porous layer (200) varies with a gradient along the axial and / or circumferential direction of the flame tube; The structural parameters include the equivalent diameter of the flow channel and the local porosity of the macroscopic flow-guiding porous layer (200).

4. The multi-layer sweating cooling flame tube according to claim 1, characterized in that, The thickness of the macroscopic flow-guiding porous layer (200) accounts for 50%-80% of the total thickness of the flame tube, wherein the total thickness of the flame tube is the sum of the thicknesses of the macroscopic flow-guiding porous layer (200), the microscopic capillary porous layer (300), and the nanoporous coating (400).

5. The multi-layer sweating cooling flame tube according to claim 1, characterized in that, The thickness of the micro-capillary porous layer (300) is 0.5 mm to 3 mm; and / or, The average pore size of the micro-capillary porous layer (300) is 10 μm-100 μm; and / or, The porosity of the micro-capillary porous layer (300) is 30%-70%.

6. The multi-layer sweating cooling flame tube according to claim 1, characterized in that, The thickness of the nanoporous coating (400) is 0.5 μm-200 μm; and / or, The nanoporous coating (400) has a nanoscale rough structure on its surface; and / or, The average pore size of the nanoporous coating (400) is less than 1 μm.

7. A method for implementing a multi-layer sweating cooling flame tube, used to prepare the multi-layer sweating cooling flame tube according to any one of claims 1-6, characterized in that, The implementation method includes: A macroscopic flow-guiding porous layer (200) and a microscopic capillary porous layer (300) are formed by processing, and the average pore size of the microscopic capillary porous layer (300) is smaller than the average pore size of the macroscopic flow-guiding porous layer (200). A nanoporous coating (400) is prepared on the surface of the micro-capillary porous layer (300) exposed to the high-temperature gas combustion side, and the nanoporous coating (400) is processed such that the average pore size of the nanoporous coating (400) is smaller than the average pore size of the micro-capillary porous layer (300).

8. The method for implementing the multi-layer sweating cooling flame tube according to claim 7, characterized in that, The macroscopic flow-guiding porous layer (200) and the microscopic capillary porous layer (300) are formed by integrated processing using selective laser melting metal additive manufacturing technology, and the microscopic capillary porous layer (300) is formed by adjusting the laser process parameters to an incompletely melted state.

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