Multi-layer sweating cooling flame tube and implementation method

Abstract

The invention relates to a multi-layer sweating cooling flame tube and an implementation method, the multi-layer sweating cooling flame tube comprises a macroscopic flow guide porous layer, a microcosmic capillary porous layer and a nano-porous coating which are sequentially stacked, the macroscopic flow guide porous layer is configured to receive cooling air, and the nano-porous coating is configured to face high-temperature fuel gas; the average pore size of the micro capillary porous layer is smaller than that of the macro flow guide porous layer, and the average pore size of the nano porous coating is smaller than that of the micro capillary porous layer. According to the multi-layer sweating cooling flame tube, the graded porous structure can spontaneously suck cooling air from the macroscopic flow guide porous layer to the microcosmic capillary porous layer under the capillary action, and finally the air uniformly seeps through the nano porous coating, so that a layer of continuous, stable and fully-covered cooling air film is formed on the high-temperature fuel gas side; and high-temperature fuel gas is isolated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engines, in particular to a multi-layer transpiration cooling flame tube and an implementation method. BACKGROUND

[0002] With the continuous development of aero-engines towards high thrust-to-weight ratio and high cycle parameters, the combustion chamber of the engine needs to organize combustion at higher inlet temperature and pressure, which leads to a sharp rise in the thermal load borne by the flame tube as a core high-temperature component of the combustion chamber. At the same time, in order to pursue higher thermal efficiency, more air is allocated to the combustion zone, which reduces the air share available for cooling the flame tube, which poses unprecedentedly harsh requirements on the cooling technology of the flame tube.

[0003] In the related art, the existing non-flame tube of an aero-engine adopts a film cooling technology, which usually opens a large number of discrete exhaust holes or slits on the wall surface of the flame tube, and sprays a jet of cooling air from the compressor to the inner wall surface of the flame tube, so as to form a layer of attached low-temperature air film on the inner wall surface of the flame tube, which is used to isolate the high-temperature combustion gas and perform convective heat exchange on the wall surface.

[0004] However, after the discrete jet leaves the film hole, it will undergo violent mixing and entrainment with the high-speed mainstream combustion gas, and is extremely easy to lift off from the wall surface, resulting in discontinuous coverage of the cooling air film, poor stability, and the formation of local "hot spots" in the inter-hole area, which leads to low cooling efficiency. SUMMARY

[0005] Therefore, it is necessary to provide a multi-layer transpiration cooling flame tube and an implementation method in view of the problem that the existing opening of exhaust holes or slits on the wall surface of the flame tube leads to discontinuous coverage of the cooling air film and poor stability.

[0006] The present application provides a multi-layer transpiration cooling flame tube, which comprises:

[0007] a macroscopic flow guide porous layer, a microscopic capillary porous layer and a nano-porous coating which are sequentially stacked, wherein the macroscopic flow guide porous layer is configured to receive cooling air, and the nano-porous coating is configured to face high-temperature combustion gas;

[0008] The average pore diameter of the microscopic capillary porous layer is smaller than the average pore diameter of the macroscopic flow guide porous layer, and the average pore diameter of the nano-porous coating is smaller than the average pore diameter of the microscopic capillary porous layer.

[0009] In one of the embodiments, the macroscopic flow guide porous layer is provided with flow guide channels arranged in stages.

[0010] In one of the embodiments, the equivalent diameter of the flow guide channels is 0.5mm-2mm.

[0011] In one of the embodiments, the flow guiding channels are biomimetic tree-like or vein-like.

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

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

[0014] In one of the embodiments, 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 nano-porous coating.

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

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

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

[0018] In one of the embodiments, the thickness of the nano-porous coating is 0.5μm-200μm; and / or,

[0019] The surface of the nano-porous coating has a nano-scale rough structure; and / or,

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

[0021] The application also provides an implementation method of the multi-layer sweat cooling flame tube, for preparing the multi-layer sweat cooling flame tube as described in any of the above embodiments, the implementation method comprising:

[0022] Processing to form the macroscopic flow guiding porous layer and the microscopic capillary porous layer, and processing to make the average pore size of the microscopic capillary porous layer smaller than the average pore size of the macroscopic flow guiding porous layer;

[0023] On the surface of the microscopic capillary porous layer exposed to the high-temperature gas side, processing to form the nano-porous coating, and processing to make the average pore size of the nano-porous coating smaller than the average pore size of the microscopic capillary porous layer.

[0024] In one of the embodiments, the macroscopic flow guiding porous layer and the microscopic capillary porous layer are integrally processed by using the selective laser melting metal additive manufacturing technology, and the microscopic capillary porous layer is formed by regulating the laser process parameters to an incomplete melting state.

[0025] The multilayer transpiration cooling flame tube is formed by sequentially stacking a macroscopic flow guiding porous layer, a microscopic capillary porous layer and a nano-porous coating layer, and limiting the average pore diameter of the microscopic capillary porous layer to be smaller than the average pore diameter of the macroscopic flow guiding porous layer, and the average pore diameter of the nano-porous coating layer to be smaller than the average pore diameter of the microscopic capillary porous layer, thereby forming a hierarchical porous structure; the hierarchical porous structure can spontaneously draw cooling air from the macroscopic flow guiding porous layer to the microscopic capillary porous layer by capillary action, and finally make the air uniformly seep through the nano-porous coating layer, so as to form a continuous, stable and comprehensive cooling air film on the high-temperature gas side, and isolate the high-temperature gas. The multilayer transpiration cooling flame tube provided by the application solves the problems of uneven coverage and easy formation of local hot spots of the traditional discrete gas film cooling. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A structural schematic diagram of the flame tube provided by the embodiment of the application.

[0027] Figure 2 A structural schematic diagram of the macroscopic flow guiding porous layer, the microscopic capillary porous layer and the nano-porous coating layer provided by the embodiment of the application.

[0028] Figure 3 A structural schematic diagram of the macroscopic flow guiding porous layer provided by the embodiment of the application.

[0029] Figure 4 A structural schematic diagram of the microscopic capillary porous layer provided by the embodiment of the application.

[0030] Figure 5 A structural schematic diagram of the nano-porous coating layer provided by the embodiment of the application.

[0031] Reference signs:

[0032] 100, multilayer transpiration cooling flame tube;

[0033] 200, macroscopic flow guiding porous layer;

[0034] 300, microscopic capillary porous layer;

[0035] 400, nano-porous coating layer. DETAILED DESCRIPTION

[0036] To make the above objectives, features and advantages of the application more apparent, specific embodiments of the application are described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to fully understand the application. However, the application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the application, so the application is not limited by the specific embodiments disclosed below.

[0037] In the description of the application, it should be understood that, if there are these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0038] In addition, if there are these terms "first", "second", these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, if the term "multiple" appears, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this application, unless otherwise explicitly specified and limited, if there are terms such as "mounting", "connecting", "connecting", "fixing" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0040] In this application, unless otherwise explicitly specified and limited, if there are similar descriptions such as "first feature on or under second feature", the meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" of the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" of the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0041] It is to be noted that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In addition, it is to be understood that when a layer is referred to as being "connected", "coupled", or "adjacent" to another element, it can be directly connected, coupled, or adjacent to the other element, or intervening elements can also be present. As used herein, the term "vertical", "horizontal", "upper", "lower", "left", "right", and the like are merely used for the purpose of illustration and do not indicate an absolute orientation.

[0042] The present application provides a multi-layer transpiration cooling flame tube 100, as shown in the figure, the multi-layer transpiration cooling flame tube 100 comprises: Figures 1 to 5

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

[0044] The average pore diameter of the microscopic capillary porous layer 300 is smaller than the average pore diameter of the macroscopic flow-guiding porous layer 200, and the average pore diameter of the nano-porous coating 400 is smaller than the average pore diameter of the microscopic capillary porous layer 300.

[0045] The multi-layer transpiration cooling flame tube 100 described above, by sequentially stacking the macroscopic flow-guiding porous layer 200, the microscopic capillary porous layer 300, and the nano-porous coating 400, and limiting the average pore diameter of the microscopic capillary porous layer 300 to be smaller than the average pore diameter of the macroscopic flow-guiding porous layer 200, and the average pore diameter of the nano-porous coating 400 to be smaller than the average pore diameter of the microscopic capillary porous layer 300, thereby forming a hierarchical porous structure; the hierarchical porous structure can spontaneously use capillary action to suck cooling air from the macroscopic flow-guiding porous layer 200 to the microscopic capillary porous layer 300, and finally make the air uniformly seep through the nano-porous coating 400, thereby forming a continuous, stable, and comprehensive cooling gas film on the side of the high-temperature combustion gas, isolating the high-temperature combustion gas. The multi-layer transpiration cooling flame tube 100 of the present application solves the problem of uneven coverage and easy formation of local hot spots in traditional discrete gas film cooling.

[0046] It is to be noted that the average pore diameter refers to the statistical average value of the pore diameter of the internal pores or channels of the porous structure.

[0047] In one of the embodiments, the macroscopic flow-guiding porous layer 200 is provided with flow-guiding channels arranged in a hierarchical manner. By providing the macroscopic flow-guiding porous layer 200 with flow-guiding channels arranged in a hierarchical manner, a structured low-flow-resistance distribution network for cooling air is established, which can transport cooling air to each region of the wall surface of the flame tube 100, providing a stable and evenly distributed air source basis for subsequent capillary suction and uniform seepage. ​

[0048] It should be noted that the hierarchical arrangement or hierarchy is used to describe the flow guide channel structure in the macroscopic flow guide porous layer, and its specific meaning refers to the multi-level, non-uniform distribution characteristics of the channel system in the topological structure. This structure is characterized in that a small number of primary channels (trunk channels) with large flow cross sections receive the incoming flow from the cooling air inlet; the primary channels are connected to a larger number of secondary channels with relatively small flow cross sections through branching or branching; according to actual needs, the secondary channels can be further branched to form finer tertiary or more levels of channels, and ultimately form a channel network with parent-child subordinate relationship covering the entire macroscopic flow guide porous layer area.

[0049] In the embodiment, the flow guide channels are bionic tree-like or vein-like. By setting the flow guide channels to a bionic tree-like or vein-like structure, the fractal characteristics of the efficient fluid transport system in nature are simulated; the bionic tree-like or vein-like structure can achieve optimal distribution of cooling air from the centralized injection point to the entire wall surface coverage area with less flow path and low flow resistance.

[0050] In other embodiments, the flow guide channels can also be in a network structure or a radial branching structure, etc., which can realize fluid distribution and transport.

[0051] In one of the embodiments, the equivalent diameter of the flow guide channels is 0.5-2 mm. By limiting the equivalent diameter of the flow guide channels to the range of 0.5-2 mm, the macroscopic flow guide porous layer 200 can have sufficient mechanical strength and structural stability while ensuring the cooling air flow capacity and maintaining low flow resistance, avoiding 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 is also known as the hydraulic diameter in the art, which is a key parameter for characterizing the geometric characteristics of non-circular cross-section flow guide channels. It is defined as the ratio of four times the channel cross-sectional area to the wet perimeter length.

[0053] In one of the embodiments, at least one structural parameter of the macroscopic flow guide porous layer 200 varies along the axial and / or circumferential direction of the flame tube 100; wherein the structural parameters include the equivalent diameter of the flow guide channels and the local porosity of the macroscopic flow guide porous layer 200. By making the structural parameters (equivalent diameter of flow guide channels and / or local porosity) of the macroscopic flow guide porous layer 200 vary 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 areas of the wall surface; specifically, in areas with higher heat load, more cooling air is automatically distributed by increasing the channel diameter or increasing the porosity, achieving "on-demand distribution" of cooling resources.

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

[0055] The above local region can be divided according to the heat load distribution of the flame tube wall surface, and generally corresponds to a region of different heat load levels. By designing different porosities in different local regions, i.e. forming a gradient distribution of porosity, the on-demand distribution of cooling gas flow can be achieved. In the region with higher heat load, a higher local porosity is set to provide a greater cooling gas flux, while in the region with lower heat load, a lower local porosity is set 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 nano-porous coating 400. By limiting the thickness of the macroscopic flow-guiding porous layer 200 to account for 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 and has sufficient space to accommodate and arrange flow-guiding channels to provide sufficient gas distribution capacity for the entire cooling system, while ensuring that the microscopic capillary porous layer 300 and the nano-porous coating 400 have reasonable thickness space to realize their functions of capillary suction and stable exhalation.

[0057] In one embodiment, the thickness of the microscopic capillary porous layer 300 is 0.5mm-3mm; and / or, the average pore diameter of the microscopic capillary porous layer 300 is 10μm-100μm; and / or, the porosity of the microscopic capillary porous layer 300 is 30%-70%. By limiting the thickness, average pore diameter and porosity of the microscopic capillary porous layer 300 to be in the ranges of 0.5mm-3mm, 10μm-100μm and 30%-70% respectively, it is not only ensured that the microscopic capillary porous layer 300 can generate a strong enough capillary force to actively suction cooling air from the macroscopic flow-guiding porous layer 200, but also that the microscopic capillary porous layer 300 itself has appropriate pore space and permeability, which can store and transport a sufficient amount of cooling medium and ensure that air is uniformly transported to the nano-porous coating 400.

[0058] In one embodiment, the nanoporous coating 400 has a thickness of 0.5 μm-200 μm; and / or, the surface of the nanoporous coating 400 has a nanoscale rough structure; and / or, the nanoporous coating 400 has an average pore size of 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 be in the nanoscale, i.e., less than 1 μm, or by providing the surface of the nanoporous coating 400 with a nanoscale rough structure, the stability of the effusion gas film in the high-speed gas flow is enhanced; at the same time, the heat transfer intensity between the gas film and the wall is enhanced, thereby forming a heat-insulating cooling barrier on the hot side.

[0059] In summary, compared with the prior art, the multilayer sweating cooling flame tube 100 of the present application has excellent comprehensive benefits. The core advantage is that through the synergistic effect of macroscopic flow guiding, capillary transport and nanoscale stability, the cooling efficiency is qualitatively improved. Specifically, this structure not only inherits the advantages of uniform coverage of traditional sweating cooling, but also realizes the "on-demand distribution" of cooling air according to the wall heat load through the unique gradient pore design, i.e., automatically providing stronger cooling in high-temperature areas, thereby fundamentally solving the "uneven distribution of water and flood" problem of homogeneous porous body cooling, significantly improving the overall cooling efficiency, and reducing the total cooling air consumption under the premise of achieving the same or better cooling effect, so that more air can be used for main combustion, which is directly beneficial to improving the thermal efficiency and thrust of the engine.

[0060] In addition, the nanoporous coating 400 located on the high-temperature gas side greatly enhances the stability of the effusion gas film in the high-speed gas flow through its nanoscale surface structure, forming a dense and full-coverage heat-insulating layer that is not easily blown away, further improving the heat-insulating effect. The entire cooling process is mainly driven by passive capillary force, without the need for complex external active control systems, and has a simple structure and high working reliability, which is extremely suitable for long-term operation in harsh engine environments with high temperature and high vibration. This passive reliability combined with high and uniform cooling capacity can significantly reduce the local peak temperature and thermal stress of the flame tube 100, effectively inhibiting the initiation and propagation of thermal fatigue cracks, thereby greatly extending the service life of the flame tube 100.

[0061] In addition, compared with the traditional single-pore-size sweating cooling structure, the hierarchical porous structure of the present application has inherent advantages in terms of anti-blocking performance. The macroscopic flow guiding layer can pre-distribute and filter the gas flow, and the gradient transition design of the microscopic and nanoscale layers reduces the possibility of impurities accumulating at narrow pore throats, effectively reducing the risk of pore blockage due to carbon deposition or foreign matter, and improving the long-term working reliability of the system.

[0062] It should be noted that in addition to the combustion chamber flame tube 100 of the aero-engine, the self-adaptive film cooling scheme based on the hierarchical porous structure provided in the present application, with its passive driving, efficient and uniform, on-demand distribution and super-strong stable full-coverage cooling characteristics, is also applicable to other environments facing extreme aerodynamic thermal load. For example, the cooling structure and method can be applied to the thermal protection system of a hypersonic aircraft to provide efficient active cooling for key parts such as sharp leading edges and control surfaces; it can also be applied to rocket engine thrust chamber walls to cope with extremely high combustion temperatures and heat flux densities; and it can also be applied to scramjet combustion chambers to solve the serious thermal protection challenges brought about by long-term high-temperature combustion.

[0063] The present application also provides an implementation method of the multilayer transpiration cooling flame tube 100, for preparing the multilayer transpiration cooling flame tube 100 of any one of the above, the implementation method comprising:

[0064] Processing to form the macroscopic flow guide porous layer 200 and the microscopic capillary porous layer 300, and processing to make the average pore size of the microscopic capillary porous layer 300 smaller than the average pore size of the macroscopic flow guide porous layer 200;

[0065] On the surface of the microscopic capillary porous layer 300 exposed to the high-temperature gas side, a nano-porous coating 400 is prepared, and processing is performed to make the average pore size of the nano-porous coating 400 smaller than the average pore size of the microscopic capillary porous layer 300.

[0066] The implementation method of the multilayer transpiration cooling flame tube 100 described above directly ensures that the product has a pore size gradient by controlling the formation of the macroscopic flow guide porous layer 200 and the microscopic capillary porous layer 300 during processing, and making the average pore size of the microscopic capillary porous layer 300 smaller than the average pore size of the macroscopic flow guide porous layer 200, and at the same time, preparing a nano-porous coating 400 with a smaller average pore size on the microscopic capillary porous layer 300. The implementation method ensures smooth connection between the functions of the three-level porous structure during the manufacturing process, and provides reliable process guarantee for finally obtaining a high-performance flame tube 100 with self-driving and self-adaptive cooling capability.

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

[0068] In one embodiment, the macroscopic flow guiding porous layer 200 and the microscopic capillary porous layer 300 are integrally formed by using a selective laser melting metal additive manufacturing technology, and the microscopic capillary porous layer 300 is formed by regulating the laser process parameters to an incomplete melting state. By using the selective laser melting metal additive manufacturing technology to integrally form the macroscopic flow guiding porous layer 200 and the microscopic capillary porous layer 300, and regulating the laser process to form the microscopic capillary porous layer 300 in an incomplete melting powder bonding structure, 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 are seamlessly transitioned and combined in material and morphology. The integrally formed process not only avoids the interface thermal resistance and potential connection failure risk of the layered structure, but also accurately and controllably prepares a complex three-dimensional structure with a specific pore size gradient, ensuring the consistency and reliability of the device.

[0069] In other embodiments, the microscopic capillary porous layer 300 is prepared from a ceramic matrix composite material; by regulating the preform structure of the ceramic fiber woven body, and combining a melt impregnation or chemical vapor impregnation process, a gradient changing porosity is formed in the microscopic capillary porous layer 300. By using the ceramic matrix composite material to prepare the microscopic capillary porous layer 300, and using the process method of regulating the preform structure of the ceramic fiber woven body combined with the melt impregnation or chemical vapor impregnation process, a gradient changing porosity distribution is actively constructed inside the microscopic capillary porous layer 300, so that the microscopic capillary porous layer 300 not only has the excellent high temperature resistance and corrosion resistance performance inherent to ceramic materials, but also can adjust the cooling gas flow according to the heat load distribution of different regions of the flame tube 100 wall surface, that is, more cooling gas is provided in the region with higher heat load through higher porosity, and less gas flow is provided in the region with lower heat load through lower porosity.

[0070] In one embodiment, the nano-porous coating 400 is in-situ grown on the substrate by anodic oxidation or thermal oxidation treatment, or is prepared as a porous ceramic layer by atmospheric plasma spraying, solution precursor plasma spraying process; the material of the porous ceramic layer is yttria-stabilized zirconia, alumina or rare earth salt.

[0071] By using anodic oxidation or thermal oxidation treatment to in-situ grow the nano-porous coating 400 on the substrate, a nano-structured surface with high bonding strength and firm interface bonding to the substrate can be formed, enhancing the thermal shock resistance and service reliability of the coating; and by using atmospheric plasma spraying or solution precursor plasma spraying process to prepare the porous ceramic layer, a nano-porous coating 400 with controllable thickness, uniform pore structure and heat insulation performance can be obtained.

[0072] The yttria-stabilized zirconia, aluminum oxide or rare earth acid salt is selected as the coating material, and the nano-porous coating 400 can maintain the structural integrity and functionality under the extreme high temperature and thermal shock environment by using the characteristics of the high melting point, low thermal conductivity, excellent high temperature stability and good erosion resistance of the ceramic material, thereby improving the stability and durability of the cooling gas film.

[0073] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0074] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that for ordinary skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A multi-layered transpiration-cooled flame channel, characterized by, The multilayer sweat cooling flame tube comprises: The macroscopic flow guide porous layer (200), the microscopic capillary porous layer (300) and the nanometer porous coating (400) are sequentially stacked, wherein the macroscopic flow guide porous layer (200) is configured to receive cooling air, and the nanometer porous coating (400) is configured to face high-temperature combustion gas; The average pore diameter of the microscopic capillary porous layer (300) is smaller than the average pore diameter of the macroscopic flow guide porous layer (200), and the average pore diameter of the nanometer porous coating (400) is smaller than the average pore diameter of the microscopic capillary porous layer (300).

2. The multi-layer sweat cooling flame tube of claim 1, wherein, The macroscopic flow guide porous layer (200) is provided with flow guide channels arranged in stages.

3. The multi-layered sweat cooling flame tube of claim 2, wherein, The equivalent diameter of the flow guide channels is 0.5mm-2mm.

4. The multi-layered sweat cooling flame tube of claim 2, wherein, The flow guide channels are bionic tree-like or vein-like.

5. The multi-layer, transpiration-cooled flame tube of claim 4, wherein, At least one structural parameter of the macroscopic flow guide porous layer (200) changes along the axial and / or circumferential direction of the flame tube. The structural parameters include the equivalent diameter of the flow guide channels and the local porosity of the macroscopic flow guide porous layer (200).

6. The multi-layer, transpiration-cooled flame tube of claim 1, wherein, The thickness of the macroscopic flow guide 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 guide porous layer (200), the microscopic capillary porous layer (300) and the nanometer porous coating (400).

7. The multi-layer, transpiration-cooled flame tube of claim 1, wherein, The thickness of the microscopic capillary porous layer (300) is 0.5mm-3mm; and / or, The average pore diameter of the microscopic capillary porous layer (300) is 10μm-100μm; and / or, The porosity of the microscopic capillary porous layer (300) is 30%-70%.

8. The multi-layer, transpiration-cooled flame tube of claim 1, wherein, The thickness of the nanometer porous coating (400) is 0.5μm-200μm; and / or, The surface of the nanometer porous coating (400) has a nanometer-scale rough structure; and / or, The average pore diameter of the nanometer porous coating (400) is less than 1μm.

9. A method of implementing a multi-layer transpiration-cooled flame channel for producing a multi-layer transpiration-cooled flame channel according to any one of claims 1 to 8, characterized in that The implementation method comprises: Processing to form the macroscopic flow guide porous layer (200) and the microscopic capillary porous layer (300), and processing to make the average pore diameter of the microscopic capillary porous layer (300) smaller than the average pore diameter of the macroscopic flow guide porous layer (200); Preparation of the nanometer porous coating (400) on the surface of the microscopic capillary porous layer (300) exposed to the high-temperature combustion gas side, and processing to make the average pore diameter of the nanometer porous coating (400) smaller than the average pore diameter of the microscopic capillary porous layer (300).

10. The method of implementing a multi-layer sweat cooled flame tube according to claim 9, wherein, The macroscopic flow guide porous layer (200) and the microscopic capillary porous layer (300) are integrally processed by using a selective laser melting metal additive manufacturing technology, and the microscopic capillary porous layer (300) is formed by regulating laser process parameters to an incomplete melting state.

Images