Flame tube cooling hole design and manufacturing method based on temperature field constraint and additive manufacturing

Abstract

The invention discloses a flame tube cooling hole designing and manufacturing method based on temperature field constraint and additive manufacturing. The flame tube cooling hole designing and manufacturing method comprises the steps that flame tube surface temperature distribution data are obtained through full-working-condition thermal simulation; based on the surface temperature distribution data of the flame tube, cooling hole optimization design of the flame tube is carried out according to the temperature threshold value and the thermal gradient distribution, and a preliminary cooling hole optimization distribution scheme is generated; the preliminary cooling hole optimized distribution scheme is introduced into the simulation environment again, the heat dissipation effect of the flame tube is verified, the temperature distribution difference of the surface of the flame tube before and after optimization is compared, the distribution scheme of the cooling holes is adjusted until the target index is met, and the final cooling hole optimized distribution scheme is output; and directly forming the cooling holes in the forming process of the flame tube by adopting a laser powder bed melting additive manufacturing process according to the final optimal distribution scheme of the cooling holes. According to the method, the flame tube cooling hole layout can be accurately optimized, and the flame tube cooling holes can be integrally manufactured.

Description

Technical Field

[0001] This invention belongs to the field of gas turbine equipment technology, specifically relating to a method for designing and manufacturing cooling holes for a flame tube based on temperature field constraints and additive manufacturing. Background Technology

[0002] As a core component of the combustion chamber in aero-engines and gas turbines, the combustor's main function is to contain and stabilize the combustion reaction and uniformly guide the high-temperature gases produced by combustion into the turbine section. During actual operation, the combustor is subjected to extreme thermal environments and high-pressure conditions, with local temperatures reaching thousands of degrees Celsius. Therefore, effectively improving the combustor's thermal management capabilities, reducing its structural thermal load, and extending its service life through reasonable cooling hole design and processing techniques is one of the key technical challenges in the manufacturing of combustion chambers for aero-engines and gas turbines.

[0003] In traditional manufacturing processes, cooling holes in the flame tube are usually completed by subsequent mechanical drilling. However, this method has the following shortcomings: 1) Limited machining accuracy. Specifically, for flame tubes with complex shapes and small-diameter cooling holes, the dimensional error of the cooling holes is large and the surface quality is poor; 2) Insufficient thermal management. Specifically, because the distribution of cooling holes in the flame tube does not correspond to the actual temperature field of the flame tube, the heat dissipation performance of the flame tube is uneven; 3) Low manufacturing efficiency. Specifically, the multiple machining and post-processing steps of the cooling holes prolong the manufacturing cycle.

[0004] Patent CN115106716A discloses a method for repairing a flame tube based on additive manufacturing technology. This patent solves the problem of deformation and cracking that occurs during the additive manufacturing repair of the flame tube, but it does not involve the optimized design of the cooling holes and cannot solve the problem of uneven cooling performance of the flame tube.

[0005] Patent CN115475958A discloses a method for manufacturing a flame tube based on laser powder bed fusion additive manufacturing technology. This patent uses a unique support and margin addition scheme to ensure the positional accuracy of small-sized cooling holes on the flame tube. However, this method is still at the level of process improvement and does not involve the optimized design of cooling holes, so it cannot solve the problem of uneven cooling performance of the flame tube.

[0006] Patent CN108592086A discloses a combustion component of an engine, an integrated design and manufacturing method for the combustion component, and an engine. This patent utilizes additive manufacturing technology to integrate the design and manufacturing of the engine's combustion component, fusing the flame tube and nozzle into a single unit. This simplifies the structure of the combustion component and reduces the support and connection structures between the various components. However, this patent does not address the optimized design of the cooling holes, thus failing to solve the problem of uneven cooling performance of the flame tube.

[0007] Patent CN112484077A discloses a high-efficiency cooling structure for the head of a flame tube, but this patent relies on structural design improvements and does not involve the optimization design of cooling holes, thus failing to solve the problem of uneven cooling performance of the flame tube. Summary of the Invention

[0008] In view of the above-mentioned deficiencies of the prior art, the present invention provides a method for designing and manufacturing cooling holes of a flame tube based on temperature field constraints and additive manufacturing. By analyzing the heat load distribution on the surface of the flame tube, the layout of the cooling holes of the flame tube can be precisely optimized. By using laser powder bed fusion additive manufacturing process, the integrated manufacturing of the cooling holes of the flame tube can be achieved.

[0009] The technical solution adopted by this invention to solve its technical problem is:

[0010] A method for designing and manufacturing cooling holes in a flame tube based on temperature field constraint and additive manufacturing includes the following steps:

[0011] S1. Full-condition thermal simulation is used to obtain surface temperature distribution data of the flame tube;

[0012] S2.1 Based on the flame tube surface temperature distribution data obtained in step S1, optimize the design of the cooling holes of the flame tube according to the temperature threshold and thermal gradient distribution, and generate a preliminary optimized distribution scheme for the cooling holes.

[0013] S2.2 Re-import the preliminary cooling hole optimization distribution scheme from step S2.1 into the simulation environment to verify the heat dissipation effect of the flame tube, compare the temperature distribution difference on the surface of the flame tube before and after optimization, adjust the cooling hole distribution scheme until the target index is met, and output the final cooling hole optimization distribution scheme.

[0014] S3. Based on the final optimized distribution scheme of cooling holes in step S2.2, the cooling holes are directly formed during the forming process of the flame tube using laser powder bed fusion additive manufacturing process.

[0015] Further, step S1 includes the following sub-steps:

[0016] S1.1 Operating Condition Settings: Based on the typical operating conditions of the gas turbine equipment, establish the heat flow boundary conditions and internal heat source distribution models of the flame tube under the corresponding operating conditions;

[0017] S1.2, Model Establishment of Flame Tube: A three-dimensional geometric model of the flame tube is established based on three-dimensional geometric modeling software. The physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are introduced based on computational fluid dynamics (CFD) and finite element method (FEM). The specific values ​​of the physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are obtained through the heat flow boundary conditions and internal heat source distribution model established in step S1.1.

[0018] S1.3 Simulation Output: The temperature distribution cloud map of the flame tube surface is obtained through numerical calculation. Based on the temperature distribution cloud map of the flame tube surface, the temperature gradient and heat flux distribution data of different regions of the flame tube surface are obtained. Let the temperature field of the flame tube surface be T(x,y), and the temperature range of the entire flame tube be [Tmin,Tmax]. The normalized temperature of the flame tube surface is defined as θ(x,y)=(T(x,y)−T min ) / (T max -T min ), where θ(x,y)∈ [0, 1].

[0019] Further, step S2.1 includes the following sub-steps:

[0020] S2.1.1 Design principles for cooling holes: reduce the hole spacing and increase the hole diameter in the high-temperature zone of the flame tube surface; increase the hole spacing and decrease the hole diameter in the low-temperature zone of the flame tube surface; and use a transitional method for the distribution design of cooling holes in the medium-temperature zone of the flame tube surface.

[0021] S2.1.2 Based on the design principles of cooling holes, design a variable periodic distribution strategy for cooling holes:

[0022] S2.1.3. Based on the variable periodic distribution strategy of cooling holes, and based on the temperature threshold and thermal gradient distribution, a preliminary optimized distribution scheme for cooling holes is generated.

[0023] Further, in step S2.1.1, the optimization basis for the cooling holes in the design principles is as follows: the heat flux density distribution function q(x,y) on the surface of the flame tube is obtained based on the heat flux distribution data of the flame tube surface, and the target cooling efficiency function η(x,y) on the surface of the flame tube is defined. The heat flux density distribution function q(x,y) and the target cooling efficiency function η(x,y) are used to establish the mapping relationship between the hole spacing of the cooling holes on the flame tube and the heat dissipation capacity of the flame tube, and the mapping relationship between the hole diameter of the cooling holes on the flame tube and the heat dissipation capacity of the flame tube is established. The optimal hole spacing and optimal hole diameter of the cooling holes in different areas of the flame tube are determined through iterative simulation.

[0024] Furthermore, step S2.1.2 specifically includes:

[0025] Let the spacing between the cooling holes be denoted as d, and let d be related to θ(x,y), then d(θ) = d min +(1-θ) p ×(d max -d min ), where p represents an engineering constant and p≥1, then when θ=1, d=d min When θ=0, d=d max ;

[0026] Let the diameter of the cooling hole be denoted as a, and let a be related to θ(x,y), then a(θ) = a min +θ q ×(a max -a min ), where q represents an engineering constant, and q≥1, then when θ=1, a=a max , when θ=0, a=a min .

[0027] Further, step S2.2 specifically involves: re-importing the preliminary cooling hole optimization distribution scheme from step S2.1.3 into the simulation environment of computational fluid dynamics (CFD) and finite element method (FEM) to verify the heat dissipation effect of the flame tube, comparing the temperature distribution difference on the surface of the flame tube before and after optimization, adjusting the hole spacing and diameter of the cooling holes until the target index is met, and outputting the final cooling hole optimization distribution scheme.

[0028] Furthermore, in step S2.2, the specific target indicators are: compared with the flame tube before optimization, the highest temperature on the surface of the optimized flame tube decreases by ΔT1, and the temperature field uniformity on the surface of the optimized flame tube is <5%.

[0029] Furthermore, in step S3: the laser in the laser powder bed fusion additive manufacturing process is generated by a single-mode fiber laser with a laser power of 200W-500W. The laser optical path is collimation, motorized zoom beam expansion, galvanometer scanning, and f-θ field lens. The zoom mechanism of the zoom beam expansion supports online continuously adjustable spot diameter control between 60μm and 150μm. During the forming process of the flame tube, it automatically focuses with the layer height and automatically allocates processing strategies based on the area label of the design area or the geometric fields d(θ) and a(θ) derived by temperature-driven design.

[0030] Furthermore, in step S3, the processing strategy is specifically as follows:

[0031] In the thin-walled and hole edge areas, a micro-positive defocusing method is adopted, and the defocusing amount is controlled between +0.05mm and +0.15mm. Specifically, in the thin-walled and hole edge areas, a small spot, low linear energy density, and multi-track contouring method is used to form the shape, wherein the hole edge area is the area ≤0.35mm away from the hole edge.

[0032] Large areas are filled using a method with large light spots and high coverage.

[0033] Furthermore, the following steps are included after step S3:

[0034] S4. Verify the quality and dimensions of the formed cooling holes, and calibrate the flow rate of the cooling holes.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention provides a method for designing and manufacturing cooling holes in a flame tube based on temperature field constraints and additive manufacturing, comprising the following steps: S1, obtaining surface temperature distribution data of the flame tube through full-condition thermal simulation; S2.1, optimizing the design of cooling holes in the flame tube based on the surface temperature distribution data obtained in step S1, according to the temperature threshold and thermal gradient distribution, and generating a preliminary optimized distribution scheme for cooling holes; S2.2, re-importing the preliminary optimized distribution scheme for cooling holes from step S2.1 into the simulation environment to verify the heat dissipation effect of the flame tube, comparing the temperature distribution difference on the surface of the flame tube before and after optimization, adjusting the distribution scheme of cooling holes until the target indicators are met, and outputting the final optimized distribution scheme for cooling holes; S3, according to the final optimized distribution scheme for cooling holes from step S2.2, using laser powder bed fusion additive manufacturing process to directly form cooling holes during the forming process of the flame tube. By introducing full-condition thermal load simulation and based on the surface temperature distribution of the flame tube, the layout of the flame tube cooling holes can be precisely optimized. Through laser powder bed fusion additive manufacturing process, the integrated manufacturing of the flame tube cooling holes can be achieved. This invention can not only significantly improve the cooling efficiency and thermal management performance of the flame tube and solve the problem of uneven cooling performance of the flame tube, but also overcome the problems of limited processing accuracy and low manufacturing efficiency of traditional drilling process, thus achieving a higher level of manufacturing quality and application value. Attached Figure Description

[0037] Figure 1 The image shows the temperature distribution cloud map of the flame tube surface and the optimized design diagram of the cooling holes obtained in a specific embodiment. Detailed Implementation

[0038] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0039] A method for designing and manufacturing cooling holes in a flame tube based on temperature field constraint and additive manufacturing includes the following steps:

[0040] S1. Full-condition thermal simulation is used to obtain surface temperature distribution data of the flame tube;

[0041] S2.1 Based on the flame tube surface temperature distribution data obtained in step S1, optimize the design of the cooling holes of the flame tube according to the temperature threshold and thermal gradient distribution, and generate a preliminary optimized distribution scheme for the cooling holes.

[0042] S2.2 Re-import the preliminary cooling hole optimization distribution scheme from step S2.1 into the simulation environment to verify the heat dissipation effect of the flame tube, compare the temperature distribution difference on the surface of the flame tube before and after optimization, adjust the cooling hole distribution scheme until the target index is met, and output the final cooling hole optimization distribution scheme.

[0043] S3. Based on the final optimized distribution scheme of cooling holes in step S2.2, the cooling holes are directly formed during the forming process of the flame tube using laser powder bed fusion additive manufacturing process.

[0044] By introducing full-condition thermal load simulation and based on the surface temperature distribution of the flame tube, the layout of the flame tube cooling holes can be precisely optimized. Through laser powder bed fusion additive manufacturing process, the integrated manufacturing of the flame tube cooling holes can be achieved. This invention can not only significantly improve the cooling efficiency and thermal management performance of the flame tube and solve the problem of uneven cooling performance of the flame tube, but also overcome the problems of limited processing accuracy and low manufacturing efficiency of traditional drilling process, thus achieving a higher level of manufacturing quality and application value.

[0045] Step S1 includes the following sub-steps:

[0046] S1.1 Operating Condition Settings: Based on the typical operating conditions of the gas turbine equipment, establish the heat flow boundary conditions and internal heat source distribution models of the flame tube under the corresponding operating conditions;

[0047] S1.2, Model Establishment of Flame Tube: A three-dimensional geometric model of the flame tube is established based on three-dimensional geometric modeling software. The physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are introduced based on computational fluid dynamics (CFD) and finite element method (FEM). The specific values ​​of the physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are obtained through the heat flow boundary conditions and internal heat source distribution model established in step S1.1.

[0048] S1.3 Simulation Output: The temperature distribution cloud map of the flame tube surface is obtained through numerical calculation. Based on the temperature distribution cloud map of the flame tube surface, the temperature gradient and heat flux distribution data of different regions of the flame tube surface are obtained. Let the temperature field of the flame tube surface be T(x,y), and the temperature range of the entire flame tube be [Tmin,Tmax]. The normalized temperature of the flame tube surface is defined as θ(x,y)=(T(x,y)−T min ) / (T max -T min), where θ(x,y)∈ [0, 1].

[0049] This step provides a database of heat loads on the surface of the flame tube under actual operating conditions of the gas turbine equipment, offering a reliable basis for subsequent optimization of cooling holes and ensuring that the layout of the flame tube cooling holes meets the thermal management requirements of the actual service environment.

[0050] Step S2.1 includes the following sub-steps:

[0051] S2.1.1 Design principles for cooling holes: reduce the hole spacing and increase the hole diameter in the high-temperature zone of the flame tube surface; increase the hole spacing and decrease the hole diameter in the low-temperature zone of the flame tube surface; and use a transitional method for the distribution design of cooling holes in the medium-temperature zone of the flame tube surface.

[0052] S2.1.2 Based on the design principles of cooling holes, design a variable periodic distribution strategy for cooling holes:

[0053] S2.1.3. Based on the variable periodic distribution strategy of cooling holes, and based on the temperature threshold and thermal gradient distribution, a preliminary optimized distribution scheme for cooling holes is generated.

[0054] In areas where the temperature exceeds a set threshold, such as above 1000°C, the local heat flux density on the surface of the flame tube is high, making it prone to thermal fatigue cracks. This invention reduces the spacing between cooling holes and increases the hole diameter in the high-temperature zone of the flame tube surface, introducing more cooling airflow per unit area to achieve efficient local heat dissipation. In areas where the temperature is below the set threshold, the heat load on the flame tube surface is relatively small. Excessive perforation would not only waste cooling airflow but also weaken the material strength. This invention increases the spacing between cooling holes and reduces the hole diameter in the low-temperature zone of the flame tube surface to achieve a rational allocation of cooling resources.

[0055] In step S2.1.1, the optimization basis for the cooling holes in the design principle is as follows: the heat flux density distribution function q(x,y) on the surface of the flame tube is obtained based on the heat flux distribution data of the flame tube surface, and the target cooling efficiency function η(x,y) on the surface of the flame tube is defined. The mapping relationship between the hole spacing of the cooling holes on the flame tube and the heat dissipation capacity of the flame tube is established using the heat flux density distribution function q(x,y) and the target cooling efficiency function η(x,y). The mapping relationship between the hole diameter of the cooling holes on the flame tube and the heat dissipation capacity of the flame tube is also established. The optimal hole spacing and optimal hole diameter of the cooling holes in different areas of the flame tube are determined through iterative simulation.

[0056] Specifically, step S2.1.2 is as follows:

[0057] Let the spacing between the cooling holes be denoted as d, and let d be related to θ(x,y), then d(θ) = d min +(1-θ)p ×(d max -d min ), where p represents an engineering constant and p≥1, then when θ=1, d=d min When θ=0, d=d max ;

[0058] Let the diameter of the cooling hole be denoted as a, and let a be related to θ(x,y), then a(θ) = a min +θ q ×(a max -a min ), where q represents an engineering constant, and q≥1, then when θ=1, a=a max , when θ=0, a=a min .

[0059] The engineering constants p and q can be used to adjust the response sensitivity of the thermal zone.

[0060] Specifically, step S2.2 involves re-importing the preliminary optimized distribution scheme of cooling holes from step S2.1.3 into the simulation environment of computational fluid dynamics (CFD) and finite element method (FEM) to verify the heat dissipation effect of the flame tube, comparing the temperature distribution difference on the surface of the flame tube before and after optimization, adjusting the hole spacing and diameter of the cooling holes until the target index is met, and outputting the final optimized distribution scheme of cooling holes.

[0061] The resulting optimized distribution of cooling holes ensures that the gas turbine equipment maintains a stable thermal field in the combustion chamber under all operating conditions.

[0062] In step S2.2, the specific target indicators are: compared with the flame tube before optimization, the highest temperature on the surface of the optimized flame tube decreases by ΔT1, and the temperature field uniformity on the surface of the optimized flame tube is <5%.

[0063] In step S3, the laser in the laser powder bed fusion additive manufacturing process is generated by a single-mode fiber laser with a power of 200W-500W. The laser optical path consists of collimation, motorized zoom beam expansion, galvanometer scanning, and f-θ field lens. The zoom mechanism of the zoom beam expansion supports online continuously adjustable spot diameter control between 60μm and 150μm. During the forming process of the flame tube, the laser automatically focuses with the layer height and automatically allocates processing strategies based on the area label of the design area or the geometric fields d(θ) and a(θ) derived by temperature-driven design.

[0064] In step S3, the processing strategy is specifically as follows:

[0065] A micro-positive defocusing method is used in the thin-walled and hole edge areas, with the defocusing amount controlled between +0.05mm and +0.15mm. Specifically, a small spot size, low linear energy density, and multi-track contouring method are used in the thin-walled and hole edge areas, where the hole edge area is the region ≤0.35mm from the hole edge.

[0066] Large-area filling uses a method with large light spots and high coverage;

[0067] The spot diameter is switched in situ during the laser scanning path, from 60μm-80μm to 100μm-150μm. During the transition segment, both the laser power and scanning speed are slowly varied for 3ms-5ms to ensure the continuity of the molten pool.

[0068] The steps following step S3 include:

[0069] S4. Verify the quality and dimensions of the formed cooling holes, and calibrate the flow rate of the cooling holes.

[0070] The formed flame tube is subjected to coordinate measuring machine (CMM) measurement and optical microscopic inspection. The diameter error of the cooling holes on the flame tube is controlled within ±0.02mm, and the surface roughness of the cooling hole wall Ra is ≤3.2μm–4.0μm. If necessary, micro-shot peening or electropolishing is used for strengthening treatment. Metallographic or CT inspection is performed on the edge area of ​​the cooling holes on the flame tube to obtain a porosity of ≤0.05%. The flow rate of the cooling holes on the flame tube is calibrated to ensure that it matches the design cooling capacity driven by the temperature field.

[0071] This invention utilizes an integrated forming process of laser powder bed fusion additive manufacturing to directly form the complex surface and cooling holes of the flame tube. This not only eliminates the errors caused by traditional drilling processes, but also optimizes the size and position of the cooling holes through precise process control and temperature simulation, thereby significantly improving the manufacturing accuracy of the cooling holes and reducing problems such as dimensional deviations and surface roughness.

[0072] By optimizing the distribution of cooling holes based on temperature simulation, this invention can accurately design the spacing and diameter of cooling holes in different regions according to the heat load distribution of the flame tube. Cooling holes are densely arranged in high-temperature regions and reduced in low-temperature regions, thereby fully improving the heat dissipation efficiency of the flame tube and effectively enhancing its thermal management performance.

[0073] The direct forming of the flame tube using laser powder bed fusion additive manufacturing eliminates the need for multiple drilling and post-processing steps in traditional manufacturing processes, significantly shortening the manufacturing cycle of the flame tube.

[0074] With optimized cooling hole design and improved manufacturing precision, the flame tube can better cope with high temperature and high pressure environments, reduce thermal fatigue, extend the service life of the flame tube, and improve its overall reliability.

[0075] In summary, compared with existing technologies, this invention solves the problems of cooling hole size deviation and surface roughness in traditional manufacturing methods by combining temperature simulation and additive manufacturing technology, which significantly improves the thermal management performance, manufacturing accuracy and service life of the flame tube, and has obvious technical advantages and practical application value. Specific Implementation

[0076] Taking the flame tube of a gas turbine combustion chamber as an example, the cooling hole design and manufacturing method based on temperature field constraints and additive manufacturing in this invention is used to optimize the design and manufacturing of the cooling holes. The specific process is as follows:

[0077] S1. Full-condition thermal simulation is used to obtain the surface temperature distribution data of the flame tube, specifically:

[0078] S1.1 Operating Condition Settings: Based on the typical operating conditions of the gas turbine, such as the typical operating conditions of rated operating condition, start-up operating condition and maximum operating condition, establish the heat flow boundary conditions and internal heat source distribution models of the flame tube under the corresponding operating conditions. Under the rated operating condition, the surface temperature distribution range of the flame tube in the combustion chamber is 800℃-1200℃, and the heat flow boundary conditions of the flame tube include a gas inlet temperature of 750℃, a gas inlet pressure of 2.5 MPa, and a cooling air inlet temperature of 650℃.

[0079] S1.2, Model Establishment of Flame Tube: A three-dimensional geometric model of the flame tube is established based on three-dimensional geometric modeling software. The physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are introduced based on computational fluid dynamics (CFD) and finite element method (FEM). The specific values ​​of the physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are obtained through the heat flow boundary conditions and internal heat source distribution model established in step S1.1.

[0080] S1.3 Simulation Output: The temperature distribution cloud map on the surface of the flame tube is obtained through numerical calculation, see... Figure 1 Based on the temperature distribution cloud map of the flame tube surface, the temperature gradient and heat flux distribution data of different regions of the flame tube surface were obtained. Among them, the local maximum temperature reached 1180℃ near the flame core region, while the temperature dropped to about 820℃ in the downstream region. According to the temperature distribution, the flame tube surface was divided into a high temperature zone of 1000℃-1200℃, a medium temperature zone of 900℃-1000℃, and a low temperature zone of 800℃-900℃.

[0081] in Figure 1The diagram shows a two-dimensional temperature distribution on the surface of the flame tube and highlights the cooling hole layout based on temperature field optimization design. In the high-temperature region, i.e. the red region, more cooling holes are needed because these areas bear a higher heat load. The holes are smaller in diameter and have a higher density to effectively improve heat dissipation. Conversely, in the low-temperature region, i.e. the blue region, fewer cooling holes are needed because the heat load is lower. Therefore, the holes are larger in diameter and have a lower density to avoid overcooling.

[0082] S2.1 Based on the flame tube surface temperature distribution data obtained in step S1, the cooling hole design of the flame tube is optimized according to the temperature threshold and thermal gradient distribution, and a preliminary optimized cooling hole distribution scheme is generated, specifically as follows:

[0083] S2.1.1 Design principles of cooling holes: In the high-temperature zone of the flame tube surface, reduce the hole spacing and increase the hole diameter to enhance heat dissipation capacity; in the low-temperature zone of the flame tube surface, increase the hole spacing and decrease the hole diameter to avoid wasting cooling airflow and prevent the flame tube structure strength from decreasing; in the medium-temperature zone of the flame tube surface, adopt a transitional method for the distribution design of cooling holes.

[0084] S2.1.2 Specific parameter design:

[0085] High temperature range of 1000℃-1200℃; cooling hole diameter 1.2mm, hole spacing 2mm;

[0086] Medium temperature range of 900℃-1000℃: cooling hole diameter 1.0mm, hole spacing 2.5mm;

[0087] Low temperature range of 800℃-900℃: cooling hole diameter 0.8mm, hole spacing 3mm;

[0088] S2.2. The specific parameter design in step S2.1.2 is used as the preliminary cooling hole optimization distribution scheme, and it is re-imported into the simulation environment of computational fluid dynamics (CFD) and finite element method (FEM) to recalculate the temperature field. Before optimization, the highest temperature on the surface of the flame tube is 1180℃, the lowest temperature is 820℃, and the temperature difference is 360℃. After optimization, the highest temperature on the surface of the flame tube is reduced to 900℃, the lowest temperature is 800℃, and the temperature difference is reduced to 100℃. The specific parameter design in step S2.1.2 is used as the final cooling hole optimization distribution scheme output.

[0089] S3. Based on the final optimized distribution scheme of cooling holes in step S2.2, the cooling holes are directly formed during the forming process of the flame tube using laser powder bed fusion additive manufacturing process. The forming layer thickness is 30μm, the laser power is 250W, and the scanning speed is 900mm / s.

[0090] S4. The formed flame tube is subjected to coordinate measuring machine and optical microscopic inspection. The diameter error of the cooling hole on the flame tube is controlled within ±0.02mm, and the surface roughness of the cooling hole wall Ra≤3.2μm. The cooling performance of the flame tube is verified in a high-temperature wind tunnel test. Compared with the flame tube prepared by the traditional drilling process, the average surface temperature of the flame tube is reduced by about 10% after optimization design, and the life is expected to be increased by more than 20%.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for designing and manufacturing cooling holes in a flame tube based on temperature field constraints and additive manufacturing, characterized in that, Includes the following steps: S1. Full-condition thermal simulation is used to obtain surface temperature distribution data of the flame tube; S2.1 Based on the flame tube surface temperature distribution data obtained in step S1, optimize the design of the cooling holes of the flame tube according to the temperature threshold and thermal gradient distribution, and generate a preliminary optimized distribution scheme for the cooling holes. S2.2 Re-import the preliminary cooling hole optimization distribution scheme from step S2.1 into the simulation environment to verify the heat dissipation effect of the flame tube, compare the temperature distribution difference on the surface of the flame tube before and after optimization, adjust the cooling hole distribution scheme until the target index is met, and output the final cooling hole optimization distribution scheme. S3. Based on the final optimized distribution scheme of cooling holes in step S2.2, the cooling holes are directly formed during the forming process of the flame tube using laser powder bed fusion additive manufacturing process.

2. The method for designing and manufacturing cooling holes in a flame tube based on temperature field constraint and additive manufacturing according to claim 1, characterized in that, Step S1 includes the following sub-steps: S1.1 Operating Condition Settings: Based on the typical operating conditions of the gas turbine equipment, establish the heat flow boundary conditions and internal heat source distribution models of the flame tube under the corresponding operating conditions; S1.2, Model Establishment of Flame Tube: A three-dimensional geometric model of the flame tube is established based on three-dimensional geometric modeling software. The physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are introduced based on computational fluid dynamics (CFD) and finite element method (FEM). The specific values ​​of the physical processes of gas flow, heat conduction, convective heat transfer and radiative heat transfer are obtained through the heat flow boundary conditions and internal heat source distribution model established in step S1.

1. S1.3 Simulation Output: The temperature distribution cloud map of the flame tube surface is obtained through numerical calculation. Based on the temperature distribution cloud map of the flame tube surface, the temperature gradient and heat flux distribution data of different regions of the flame tube surface are obtained. Let the temperature field of the flame tube surface be T(x,y), and the temperature range of the entire flame tube be [Tmin,Tmax]. The normalized temperature of the flame tube surface is defined as θ(x,y)=(T(x,y)−T min ) / (T max -T min ), where θ(x,y)∈ [0, 1].

3. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 2, characterized in that, Step S2.1 includes the following sub-steps: S2.1.1 Design principles for cooling holes: reduce the hole spacing and increase the hole diameter in the high-temperature zone of the flame tube surface; increase the hole spacing and decrease the hole diameter in the low-temperature zone of the flame tube surface; and use a transitional method for the distribution design of cooling holes in the medium-temperature zone of the flame tube surface. S2.1.2 Based on the design principles of cooling holes, design a variable periodic distribution strategy for cooling holes: S2.1.

3. Based on the variable periodic distribution strategy of cooling holes, and based on the temperature threshold and thermal gradient distribution, a preliminary optimized distribution scheme for cooling holes is generated.

4. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 3, characterized in that, In step S2.1.1, the optimization basis for the cooling holes in the design principle is as follows: the heat flux density distribution function q(x,y) on the surface of the flame tube is obtained based on the heat flux distribution data of the flame tube surface, and the target cooling efficiency function η(x,y) on the surface of the flame tube is defined. The mapping relationship between the hole spacing of the cooling holes on the flame tube and the heat dissipation capacity of the flame tube is established using the heat flux density distribution function q(x,y) and the target cooling efficiency function η(x,y). The mapping relationship between the hole diameter of the cooling holes on the flame tube and the heat dissipation capacity of the flame tube is also established. The optimal hole spacing and optimal hole diameter of the cooling holes in different areas of the flame tube are determined through iterative simulation.

5. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 3, characterized in that, Step S2.1.2 specifically includes: Let the spacing between the cooling holes be denoted as d, and let d be related to θ(x,y), then d(θ) = d min +(1-θ) p ×(d max -d min ), where p represents an engineering constant and p≥1, then when θ=1, d=d min When θ=0, d=d max ; Let the diameter of the cooling hole be denoted as a, and let a be related to θ(x,y), then a(θ) = a min +θ q ×(a max -a min ), where q represents an engineering constant, and q≥1, then when θ=1, a=a max , when θ=0, a=a min .

6. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 3, characterized in that, Step S2.2 specifically involves: re-importing the preliminary cooling hole optimization distribution scheme from step S2.1.3 into the simulation environment of computational fluid dynamics (CFD) and finite element method (FEM) to verify the heat dissipation effect of the flame tube, comparing the temperature distribution difference on the surface of the flame tube before and after optimization, adjusting the hole spacing and diameter of the cooling holes until the target index is met, and outputting the final cooling hole optimization distribution scheme.

7. A method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing, as described in claim 1 or 6, characterized in that, In step S2.2, the specific target indicators are: compared with the flame tube before optimization, the highest temperature on the surface of the optimized flame tube decreases by ΔT1, and the temperature field uniformity on the surface of the optimized flame tube is <5%.

8. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 5, characterized in that, In step S3: The laser in the laser powder bed fusion additive manufacturing process is generated by a single-mode fiber laser with a power of 200W-500W. The laser optical path is collimation, motorized zoom beam expansion, galvanometer scanning, and f-θ field lens. The zoom mechanism of the zoom beam expansion supports online continuously adjustable spot diameter control between 60μm and 150μm. During the forming process of the flame tube, the laser automatically focuses with the layer height and automatically allocates processing strategies based on the area label of the design area or the geometric fields d(θ) and a(θ) derived by temperature-driven design.

9. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 8, characterized in that, In step S3, the processing strategy is as follows: In the thin-walled and hole edge areas, a micro-positive defocusing method is adopted, and the defocusing amount is controlled between +0.05mm and +0.15mm. Specifically, in the thin-walled and hole edge areas, a small spot, low linear energy density, and multi-track contouring method is used to form the shape, wherein the hole edge area is the area ≤0.35mm away from the hole edge. Large areas are filled using a method with large light spots and high coverage.

10. The method for designing and manufacturing cooling holes for a flame tube based on temperature field constraint and additive manufacturing according to claim 1, characterized in that, Step S3 is followed by the following steps: S4. Verify the quality and dimensions of the formed cooling holes, and calibrate the flow rate of the cooling holes.

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