Method for designing pit array structure on wall surface of combustion chamber, and combustion chamber

Abstract

Disclosed are a method for designing a pit array structure on a wall surface of a combustion chamber, and a combustion chamber. The method comprises: extracting a three-dimensional fluid model and performing a bench test; establishing an in-cylinder combustion and emission simulation model, and verifying same; performing a temperature field bench test on a cylinder head, a piston and a cylinder liner; establishing a heat transfer simulation model, and verifying same; establishing a thermo-mechanical coupling simulation model; performing parameterized design of a pit array structure for the piston, the cylinder liner and the cylinder head, establishing a collaborative optimization mathematical model for pit array structure design, acquiring an optimal solution set, and selecting a typical solution; and processing key components in the typical solution, performing a mounting test, and obtaining an optimal design solution for the pit array structure by means of the test. The pit array structure obtained by the collaborative optimization design method of the present invention can not only reduce the weight of the components, but also enable a turbulent layer formed near the wall surface of the combustion chamber to promote the mixing of oil and gas, thereby reducing nitrogen oxides and particulate matter, and improving the combustion performance of the engine.

Description

A method for designing a concave array structure on the combustion chamber wall and the combustion chamber Technical Field

[0001] This invention relates to an engine combustion chamber, and more particularly to a method for the collaborative optimization design of a combustion chamber wall recess array structure and a combustion chamber thereof. Background Technology

[0002] In recent years, reducing carbon emissions and even achieving carbon neutrality has become a common pursuit worldwide, which requires engines to continuously develop towards low carbon emissions, cleaner emissions, and lighter weight.

[0003] To meet these development needs, increasing engine power density and combustion pressure has become a research focus. Therefore, developing efficient and clean combustion systems is key to achieving these requirements.

[0004] CN114526151A discloses a combustion chamber and a diesel engine. The bottom of the combustion chamber recess includes an upwardly convex, rotating central protrusion and a circumferential annular recess surrounding the central protrusion. The recess in this patent is annular and exists only on the piston structure, thus not achieving any weight reduction. CN115355082A discloses a combustion chamber structure for a gas engine with accelerated combustion function, where the combustion chamber recess is located on the piston top. However, the recess in this patent has an arc-shaped structure and communicates with the flow inlet, and lacks an array feature. CN114810329A discloses a combustion chamber and a gas engine. The circumferential wall of the combustion chamber recess includes two main tumble guide walls and two intersecting tumble guide walls that alternate smoothly and sequentially along the circumference. The two main tumble guide walls and the bottom surface of the combustion chamber recess together form an open recess structure, while the two intersecting tumble guide walls and the bottom surface of the combustion chamber recess together form a narrowed recess structure. The recess in this patent is only on the piston structure, and this structure is merely a variation of the piston combustion chamber structure, without achieving the goal of piston weight reduction. CN117128105A discloses a piston, combustion chamber, and engine, in which a combustion chamber recess is provided on the top surface of the piston, and multiple flow channels are provided on the sidewalls of the piston surrounding the combustion chamber recess. The recess in this patent is only on the piston structure, and the recess structure is accompanied by a flow channel structure, without optimizing the position, shape, or number of the recess. CN 117108395A discloses a combustion chamber, combustion system, its design method, and engine, in which the combustion chamber recess has alternating ridges protruding towards the central axis of the combustion chamber and indentations receding away from the central axis of the combustion chamber on the circumferential sidewalls surrounding the central boss. The indentations in this patent are only on the piston structure and do not achieve the purpose of component weight reduction. CN213510911U discloses a piston and a diesel engine having the same. The piston's top surface has multiple arc-shaped recesses along its circumferential direction. One end of each arc-shaped recess has an arc-shaped wall, and the other end communicates with a circular recess. The recesses in this patent have an arc-shaped structure and connect to the circular recesses; their number and position are related to the number and position of the fuel injection jets. CN113389634A discloses a squeeze-flow high-turbulence centrifugal piston combustion chamber and combustion system. The combustion chamber consists of multiple recesses. The recesses near the piston center are interconnected, and the recesses near the piston outer edge are spaced apart. This recess structure is merely a variation on the piston combustion chamber structure and does not achieve the goal of piston weight reduction.

[0005] In summary, current recessed designs for combustion chamber walls are limited to piston components. Most piston recess structures are merely variations of the piston head structure, lacking array features and failing to optimize the position, shape, or number of recesses. Essentially, they do not achieve the goal of reducing piston component weight. Therefore, to significantly improve combustion system efficiency and achieve component weight reduction, incorporating recessed structures on combustion chamber wall components is crucial. This can provide technical support and theoretical basis for the development and optimization design of engine combustion chamber systems.

[0006] The current design of the recess in the combustion chamber has the following main shortcomings:

[0007] 1) Only the piston, which is one of the components of the combustion chamber, is provided with a recess, but the structure of the recess is not systematically analyzed, so it is impossible to determine whether the introduction of the recess has a beneficial or detrimental effect on the entire combustion chamber system.

[0008] 2) No optimization was done on the location, shape, or number of pits, especially the synergistic optimization design that combines the combustion and emission performance, heat transfer, and reliability of the combustion chamber system;

[0009] 3) It does not address the goal of reducing the weight of key components that make up the combustion chamber. Summary of the Invention

[0010] This invention addresses the problems existing in the prior art by providing a collaborative optimization design method for the array structure of recesses on the combustion chamber wall. Through a systematic approach involving experimental testing, simulation modeling and analysis, and further experimental verification of the optimized scheme, this invention establishes a complete and effective collaborative optimization design method for the array structure of recesses on the combustion chamber wall, providing technical support and theoretical basis for the development and optimization design of engine combustion chamber systems.

[0011] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0012] A collaborative optimization design method for the array structure of recesses on the combustion chamber wall includes the following steps:

[0013] Step 1: Extract the three-dimensional fluid model of the combustion chamber from the assembled three-dimensional solid model of the engine;

[0014] Step 2: Conduct bench tests on the engine to obtain in-cylinder pressure curves, heat release rate curves, and performance indicators for power, economy, and emissions.

[0015] Step 3: Establish an in-cylinder combustion and emission simulation model of the engine and set up and calculate the solver; verify the accuracy of the in-cylinder combustion and emission simulation model through experimental data obtained from experiments;

[0016] Step 4: Conduct temperature field bench tests on the engine cylinder head, piston, and cylinder liner;

[0017] Step 5: Establish heat transfer simulation models of key components related to the combustion chamber, such as pistons, cylinder liners, and cylinder heads, and set up and calculate the solver.

[0018] Step 6: Verify the accuracy of the heat transfer simulation model of the piston, cylinder liner, and cylinder head through temperature field tests of key components;

[0019] Step 7: Establish thermo-mechanical coupling simulation models of key components related to the combustion chamber, such as pistons, cylinder liners, and cylinder heads, and set up and calculate the solver.

[0020] Step 8: Parametrically design the pit array structure on the piston, cylinder liner, and cylinder head to create a sufficiently large design space;

[0021] Step 9: Extract a three-dimensional fluid model for each sample point in the design space according to Step 1, establish an engine in-cylinder combustion and emission simulation model, set up and calculate the solver, and extract the characteristic parameters representing the combustion performance and emission performance of each sample point.

[0022] Step 10: Further, for each sample point in the design space, establish heat transfer simulation models and thermo-mechanical coupling simulation models of key components related to the combustion chamber, such as pistons, cylinder liners, and cylinder heads, according to Step 5, and set and calculate the solver, and extract the characteristic parameters that characterize the heat transfer characteristics and reliability performance of each sample point.

[0023] Step 11: Establish a collaborative optimization mathematical model for the pit array structure design, obtain the optimal solution set, and select no less than 3 typical solutions.

[0024] Step 12: Use 3D printing technology to process the key components of the typical solution, namely piston, cylinder liner and cylinder head.

[0025] Step 13: Install the newly designed key components and repeat the tests in Steps 3 and 4.

[0026] Step 14: Obtain the optimal pit array structure design scheme by comparing experimental data.

[0027] Furthermore, the three-dimensional fluid model in step 1 consists of the piston top surface, cylinder wall, cylinder head, intake manifold, exhaust manifold, intake valve, exhaust valve, intake inlet, and exhaust outlet.

[0028] Furthermore, the power, economy, and emissions performance indicators tested in step 2 of the engine bench test mainly include engine speed, torque and power, fuel consumption rate, oil consumption, CO emissions, and NO emissions. x Emissions, HC emissions, smoke opacity, etc.

[0029] Furthermore, in step 3, after the simulation model of combustion and emissions in the engine cylinder is completed, the in-cylinder pressure curve under the last working cycle is extracted and compared with the test data under the same working conditions. The verification standard is: the relative error between the simulation value and the test value is ≤5%.

[0030] Furthermore, in step 4, temperature field test measurement points are arranged on the cylinder head, with the measurement points distributed in a circle around the center of the cylinder head's fire-facing nose area, and no fewer than four measurement points are required. Temperature field test measurement points are also arranged on the cylinder liner, with the measurement points covering the corresponding piston positions at top dead center, bottom dead center, and mid-run, and no fewer than three measurement points are required. Finally, temperature field test measurement points are arranged on the piston, with the measurement points distributed in a circle around the center of the combustion chamber, and no fewer than three measurement points are required.

[0031] Furthermore, in step 5, the heat transfer simulation model of the piston, cylinder liner, and cylinder head adopts the third type of thermal boundary loading convective heat transfer coefficient and surface temperature.

[0032] Furthermore, the verification standard for the accuracy of the simulation model of heat transfer of piston, cylinder liner and cylinder head in step 6 is: the relative error between the simulation value and the experimental value is ≤5%.

[0033] Furthermore, the gas pressure loading values ​​of the piston, cylinder liner, and cylinder head in step 7 depend on the specific test conditions. The test conditions should include at least one operating point, namely the maximum torque operating point or the calibration operating point.

[0034] Furthermore, in step 8, a recessed array structure is arranged on the top surface of the piston combustion chamber, the firing surface of the cylinder head, and the inner wall of the cylinder liner, respectively. The recessed array structure is determined by the position and shape of the recesses. The recess positions on the piston and cylinder head are referenced to the center of the physical structure, and initial recessed structures are set at different distances from the center, with no fewer than two initial recessed structures. The recess shape is a sphere, cone, cylinder, or polygon, or any combination thereof. Furthermore, with the center as a designated point, a circular layout is used, with the number of recesses evenly distributed on the circumference, and no fewer than four recesses on a single circumference. Further, a recessed structure is arranged on the cylinder liner portion above the piston's top dead center. The recess shape is a sphere, cone, cylinder, or polygon, or any combination thereof. The recessed structures are on the same horizontal plane and evenly distributed on the circumference, with no fewer than four recesses. Even further, the recessed structure arrangement should be on at least one physical component.

[0035] Furthermore, in step 9, the characteristic parameters representing combustion performance and emission performance that are directly extracted or indirectly calculated through the simulation model should include in-cylinder pressure curve, in-cylinder heat release rate curve, in-cylinder average temperature curve, in-cylinder average turbulent kinetic energy curve, indicated fuel consumption, indicated thermal efficiency, CO emissions, NOx emissions, HC emissions, smoke opacity, etc.

[0036] Furthermore, in step 10, the characteristic parameters that characterize the heat transfer properties and reliability performance, which are directly extracted or indirectly calculated through the simulation model, should include the highest temperature, the maximum thermal stress, the maximum thermomechanical coupling stress, and the minimum safety factor.

[0037] Furthermore, the objective function in the collaborative optimization mathematical model for the pit array structure design in step 11 should include indicators of thermal efficiency, maximum thermal stress, and minimum safety factor.

[0038] Furthermore, the software involved in the collaborative optimization of the pit array structure includes CONVERGE, UG, HYPERMESH, ABAQUS, FEMFAT, and MATLAB.

[0039] Furthermore, the model processing work, such as 3D parametric modeling of the physical object and extraction of the fluid domain, was completed in UG software; the in-cylinder combustion and emission simulation model was established in CONVERGE software; the component mesh was generated in HYPERMESH software; the heat transfer simulation model of piston, cylinder liner and cylinder head was established in ABAQUS software with thermo-mechanical coupling simulation; the reliability index of the components, i.e. the minimum safety factor, was calculated and obtained in FEMFAT software; and finally, the collaborative optimization mathematical model of the pit array structure design was constructed in MATLAB software.

[0040] The beneficial effects of this invention include:

[0041] This study establishes a complete and effective collaborative optimization design method for combustion chamber wall recess array structures by incorporating recess array structures in pistons, cylinder liners, and cylinder heads, combined with parametric modeling, simulation analysis, and experimental testing. This method can objectively, systematically, and quantitatively verify the effectiveness of the structural design, providing technical support and theoretical basis for the development and optimization design of engine combustion chamber systems. Specifically:

[0042] (1) By setting a recessed array structure in the piston, cylinder liner and cylinder head of the parts, the weight of the parts is reduced, which can meet the future lightweight development needs of the whole machine and reduce fuel consumption.

[0043] (2) By setting a pit array structure on the combustion chamber wall, the in-cylinder oil-air mixing process is changed, which can promote the formation of vortex around the pit structure, making the oil-air mixing more uniform, improving the combustion and emission performance of the engine, and meeting the future development needs of the whole machine for low carbonization and cleanliness.

[0044] (3) This method can evaluate the design of pit array structure from the perspective of theoretical and practical objectivity, systematicity and reference quantitative data, and has high feasibility and feasibility. Attached Figure Description

[0045] The invention will now be further described with reference to the accompanying drawings:

[0046] Figure 1 is a flowchart of the method of the present invention;

[0047] Figure 2 is a flowchart of the method according to an embodiment of the present invention;

[0048] Figure 3 is a schematic diagram of the assembly of piston, cylinder liner, and cylinder head components; in the figure: the reference numerals are: 1-cylinder head, 2-cylinder head recess, 3-intake port, 4-exhaust port, 5-injector hole, 6-cylinder liner, 7-cylinder liner recess, 8-piston, 9-piston recess.

[0049] Figure 4 is a schematic diagram of the piston;

[0050] Figure 5 is a schematic diagram of the cylinder head;

[0051] Figure 6 is a schematic diagram of the cylinder liner. Detailed Implementation

[0052] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0053] Referring to the flowcharts shown in Figures 1 and 2, the following description uses the collaborative optimization design of a recessed array structure on the combustion chamber wall of a diesel engine as an example. This design method includes the following steps:

[0054] 1) Extract the three-dimensional fluid model of the combustion chamber from the assembled three-dimensional solid model of the engine. The three-dimensional fluid model consists of the piston top surface, cylinder wall, cylinder head, intake manifold, exhaust manifold, intake valve, exhaust valve, intake inlet, exhaust outlet, etc.

[0055] 2) Bench tests were conducted on the engine to obtain in-cylinder pressure curves, heat release rate curves, and performance indicators for power, economy, and emissions. The power, economy, and emissions performance indicators obtained from the bench tests mainly include engine speed, torque and power, fuel consumption rate, oil consumption, CO emissions, and NO emissions. xEmissions, HC emissions, smoke opacity, etc.

[0056] 3) Establish an in-cylinder combustion and emission simulation model for the engine and set up and calculate the solver. Verify the accuracy of the simulation model using experimental data obtained from experiments. The verification standard is as follows: After the in-cylinder combustion and emission simulation model is completed, extract the in-cylinder pressure curve under the last working cycle and compare it with the experimental data under the same operating conditions. The relative error between the simulation value and the experimental value should be ≤5%.

[0057] 4) Perform temperature field bench tests on the engine cylinder head, piston, and cylinder liner. For the cylinder head, arrange the temperature field test points in a circular pattern around the center of the cylinder head's firing face, with no fewer than four points. For the cylinder liner, arrange the temperature field test points, including the positions of the corresponding piston at top dead center, bottom dead center, and mid-range, with no fewer than three points. For the piston, arrange the temperature field test points in a circular pattern around the center of the combustion chamber, with no fewer than three points.

[0058] 5) Establish heat transfer simulation models of key components related to the combustion chamber, such as pistons, cylinder liners, and cylinder heads, and set up and calculate the solver. In the simulation model, the third type of thermal boundary is used to load the convective heat transfer coefficient and surface temperature.

[0059] 6) Verify the accuracy of the heat transfer simulation models of the piston, cylinder liner, and cylinder head through temperature field tests of key components. The verification standard is: the relative error between the simulated values ​​and the experimental values ​​of the heat transfer simulation models of the piston, cylinder liner, and cylinder head is ≤5%.

[0060] 7) Establish thermo-mechanical coupling simulation models of key components related to the combustion chamber, such as pistons, cylinder liners, and cylinder heads, and set up and calculate the solver. The gas pressure loading values ​​of pistons, cylinder liners, and cylinder heads depend on the specific test conditions. The test conditions should include at least one operating point, namely the maximum torque operating point or the calibration operating point.

[0061] 8) Parametrically design the recess array structure on the piston, cylinder liner, and cylinder head to construct a sufficiently large design space. Specifically, recess array structures are arranged on the top surface of the piston combustion chamber, the firing surface of the cylinder head, and the inner wall of the cylinder liner, as shown in Figure 3. The recess array structure is determined by the position and shape dimensions of the recesses. The recess positions on the piston and cylinder head are referenced to the center of the physical structure, and initial recess structures are set at different distances from the center, with no fewer than two initial recess structures. The recess shapes are spheres, cones, cylinders, or polygons, or any combination thereof. Furthermore, with the center as the designated point, based on a circular layout, the recesses are evenly distributed on the circumference, with no fewer than four recesses on a single circumference. A schematic diagram of the recesses on the piston is shown in Figure 4, and a schematic diagram of the recesses on the cylinder head is shown in Figure 5. Further, recess structures are set on the physical part of the cylinder liner above the top dead center of the piston, with recess shapes being spheres, cones, cylinders, or polygons, or any combination thereof. Furthermore, the recessed structures are located on the same horizontal plane and are evenly distributed around the circumference, with a minimum of four recesses. A schematic diagram of the recesses on the cylinder liner is shown in Figure 6. Moreover, the recessed structures should be present on at least one physical object.

[0062] 9) For each sample point in the design space, extract the three-dimensional fluid model according to step (1), establish the engine in-cylinder combustion and emission simulation model, set up and calculate the solver, and extract the characteristic parameters representing the combustion performance and emission performance of each sample point. The characteristic parameters representing the combustion performance and emission performance extracted directly or indirectly by the simulation model should include the in-cylinder pressure curve, in-cylinder heat release rate curve, in-cylinder average temperature curve, in-cylinder average turbulent kinetic energy curve, indicated fuel consumption, indicated thermal efficiency, CO emission, NOx emission, HC emission, smoke opacity, etc.

[0063] 10) Further, for each sample point in the design space, establish heat transfer simulation models and thermo-mechanical coupling simulation models of key components related to the combustion chamber, such as pistons, cylinder liners, and cylinder heads, according to step (5), and set up and calculate the solver, and extract the characteristic parameters representing the heat transfer characteristics and reliability performance of each sample point. The characteristic parameters representing the heat transfer characteristics and reliability performance directly extracted or indirectly calculated by the simulation model should include the highest temperature, maximum thermal stress, maximum thermo-mechanical coupling stress, minimum safety factor, etc.

[0064] 11) Establish a collaborative optimization mathematical model for the design of the pit array structure, obtain the optimal solution set, and select no fewer than three typical solutions. The objective function in the collaborative optimization mathematical model should include indicators of thermal efficiency, maximum thermal stress, and minimum safety factor.

[0065] 12) Use 3D printing technology to process key components such as pistons, cylinder liners, and cylinder heads in typical solutions.

[0066] 13) Install the newly designed key components and repeat the tests in steps 2) and 4).

[0067] 14) Obtain the optimal pit array structure design scheme by comparing experimental data.

Claims

1. A method for designing a concave pit array structure of a combustion chamber wall surface, characterized by, The method comprises the following steps: Step 1: extracting a three-dimensional fluid model of the combustion chamber in the three-dimensional entity model of the engine assembled; Step 2: performing a bench test on the engine to obtain the in-cylinder pressure curve, heat release rate curve, and dynamic, economic and emission performance indicators; Step 3: establishing an engine in-cylinder combustion and emission simulation model and setting and calculating the solver; verifying the accuracy of the engine in-cylinder combustion and emission simulation model through the test data obtained by the test; Step 4: performing a temperature field bench test on the cylinder head, piston and cylinder sleeve of the engine; Step 5: establishing a heat transfer simulation model of the key components related to the combustion chamber, i.e. the piston, cylinder sleeve and cylinder head, and setting and calculating the solver; Step 6: verifying the accuracy of the piston, cylinder sleeve and cylinder head heat transfer simulation model through the key component temperature field test; Step 7: establishing a thermal-mechanical coupling simulation model of the key components related to the combustion chamber, i.e. the piston, cylinder sleeve and cylinder head, and setting and calculating the solver; Step 8: constructing a large enough design space and parameterizing the dimple array structure on the piston, cylinder sleeve and cylinder head; Step 9: extracting a three-dimensional fluid model according to step 1 for each sample point in the design space, establishing an engine in-cylinder combustion and emission simulation model and setting and calculating the solver, and extracting characteristic parameters of each sample point representing combustion performance and emission performance; Step 10: further establishing a heat transfer simulation model and a thermal-mechanical coupling simulation model of the key components related to the combustion chamber, i.e. the piston, cylinder sleeve and cylinder head, according to step 5 for each sample point in the design space, and setting and calculating the solver, and extracting characteristic parameters of each sample point representing heat transfer characteristics and reliability performance; Step 11: establishing a collaborative optimization mathematical model of the dimple array structure design to obtain an optimal solution set; Step 12: machining the key components, i.e. the piston, cylinder sleeve and cylinder head, in the typical solution; Step 13: installing the newly designed key components and repeating the tests of steps 3 and 4; Step 14: obtaining the best dimple array structure design scheme through comparison of the test data.

2. The design method of claim 1, wherein: in step 1, the three-dimensional fluid model comprises the piston top surface, the cylinder wall, the cylinder head, the intake port, the exhaust port, the intake valve, the exhaust valve, the intake inlet and the exhaust outlet; In step 2, the power, economic and emission performance indicators include speed, torque and power, fuel consumption, oil consumption, CO emission, NO x HC emission and smoke intensity; in step 3, verifying the accuracy of the engine in-cylinder combustion and emission simulation model comprises: extracting the in-cylinder pressure curve under the last working cycle, comparing it with the test data under the same working condition, and verifying that the relative error between the simulation value and the test value is ≤5%.

3. The design method of claim 1, wherein, in step 4, further comprising: arranging temperature field test points on the cylinder head, and the test points should be circularly distributed at the center of the cylinder head fire surface nose bridge area with more than 4 test points; arranging temperature field test points on the cylinder sleeve, and the test points should include the positions of the corresponding piston at the top dead center, bottom dead center and running midpoint with more than 3 test points; arranging temperature field test points on the piston, and the test points should be circularly distributed at the center of the combustion chamber with more than 3 test points.

4. The design method of claim 1, wherein: In step 5, the heat transfer simulation model of the piston, cylinder liner and cylinder head adopts the third type of thermal boundary loading convective heat transfer coefficient and surface temperature; In step 6, the verification standard is: the relative error between the simulated value and the experimental value is ≤5%; In step 7, the gas pressure loading values ​​for the piston, cylinder liner, and cylinder head depend on the specific test conditions, which may include the maximum torque condition or the calibration condition.

5. The design method of claim 1, wherein, Step 8 also includes: A recessed array structure is arranged on the top surface of the piston combustion chamber, the fire surface of the cylinder head, and the inner wall of the cylinder liner. The recessed array structure is determined by the position and shape of the recesses. The position of the recesses on the piston and cylinder head is referenced to the center of the actual structure. The initial recessed structure is set at a different distance from the center of the actual structure. The number of initial recessed structures is more than two. The pit shape is sphere, cone and / or cylinder or polygon; Taking the center of the physical structure as a designated point, based on a circular layout, several pits are evenly distributed on the circumference, and the number of pits on a single circumference is more than 4.

6. The design method as described in claim 5, characterized in that: A recessed structure is provided on the cylinder liner above the top dead center of the piston. The recessed structures are on the same horizontal plane and are evenly distributed on the circumference. The recessed structures are arranged on at least one part of the cylinder liner.

7. The design method as described in claim 1, characterized in that: In step 9, characteristic parameters representing combustion performance and emission performance are directly extracted or indirectly calculated through simulation models, including in-cylinder pressure curve, in-cylinder heat release rate curve, in-cylinder average temperature curve, in-cylinder average turbulent kinetic energy curve, indicated fuel consumption, indicated thermal efficiency, CO emissions, NOx emissions, HC emissions, and smoke opacity.

8. The design method as described in claim 1, characterized in that: In step 10, characteristic parameters representing heat transfer characteristics and reliability performance are directly extracted or indirectly calculated through simulation models, including maximum temperature, maximum thermal stress, maximum thermomechanical coupling stress, and minimum safety factor.

9. The design method according to any one of claims 1-8, characterized in that: In step 11, the objective function in the collaborative optimization mathematical model of the pit array structure design includes the indicative thermal efficiency, maximum thermal stress, and minimum safety factor.

10. A combustion chamber obtained by the combustion chamber wall recess array structure design method as described in any one of claims 1-9.

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