A method and system for optimizing a liquid rocket engine flange structure

Abstract

The application discloses a liquid rocket engine flange structure optimization method and system, comprising: sampling and modeling all size parameters of the flange structure to obtain a flange structure geometric model; performing first finite element mesh division on the flange structure geometric model to perform strength analysis, and screening out several key size parameters in front of the flange structure maximum equivalent stress S1 through sensitivity analysis; performing second finite element mesh division on the flange structure geometric model to perform flange structure sealing analysis, and respectively screening out several key size parameters in front of the flange structure maximum separation d and the flange structure leakage rate L through sensitivity analysis; based on the sampling sample points, taking the flange structure maximum equivalent stress S1, the flange structure maximum separation d, the flange structure leakage rate L and the flange structure weight M as output response values, establishing a Kriging surrogate model; and establishing a flange structure optimization model based on the Kriging surrogate model and performing optimization. R R ​​

Description

Technical Field

[0001] This application relates to the field of liquid rocket engine technology, and in particular to a method and system for optimizing the flange structure of a liquid rocket engine. Background Technology

[0002] Flange connections are widely used in large-diameter piping systems of liquid rocket engines due to their high strength, simple structure, and reusability, and are typically sealed using sealing rings. However, because liquid rocket engines operate under complex conditions, flange structures must withstand high-pressure and low-temperature loads. Under the combined effects of temperature and pressure, flange deformation can lead to minute separation of the sealing surface, causing a significant reduction in the localized clamping force of the gasket. This can potentially cause propellant leakage and even fire. Therefore, the sealing performance of flange structures must be given high priority during the design phase.

[0003] In addition, the weight of the liquid rocket engine is a key factor affecting the rocket's carrying capacity. Therefore, it is necessary to optimize the structure of the liquid rocket engine, including the flange structure. However, the flange structure has many dimensions, and the optimization design involves a large amount of finite element simulation calculations. Using traditional optimization methods is inefficient. Summary of the Invention

[0004] In view of this, the present invention provides a method and system for optimizing the flange structure of a liquid rocket engine. By using a Kriging proxy model to replace the complex finite element simulation model, and comprehensively considering the influencing factors of flange structure strength and sealing performance, an optimization model for flange structure is established to optimize the flange structure design, thereby reducing the computational cost of flange structure optimization and improving optimization efficiency.

[0005] To address the aforementioned technical problems, a first aspect of the present invention discloses a method for optimizing the flange structure of a liquid rocket engine, the method comprising:

[0006] S1: Sampling of all dimensional parameters of the flange structure, modeling based on the sample points, and obtaining the flange structure geometric model; wherein, the flange structure includes: a first flange, a second flange, a sealing ring, and bolts and nuts; flange structure geometric models with different dimensional parameters have different flange structure weights M;

[0007] S2: Perform the first finite element mesh generation on the geometric model of the flange structure, set the material properties of some components of the flange structure, apply loads and boundary conditions to perform strength analysis, and take the maximum equivalent stress S1 of the flange structure as the target response. Through sensitivity analysis, select several key dimension parameters that have the greatest impact on the maximum equivalent stress S1 of the flange structure.

[0008] S3: Perform a second finite element mesh generation on the geometric model of the flange structure, set the material properties of all components of the flange structure, apply loads and boundary conditions to perform a flange structure sealing performance analysis, using the maximum separation amount d and the flange structure leakage rate L of the flange structure as the parameters. R As the target response, sensitivity analysis was used to screen out the maximum separation amount d and the leakage rate L of the flange structure. R Several key dimensional parameters that have an impact;

[0009] S4: Based on the aforementioned sample points, the maximum equivalent stress S1 of the flange structure, the maximum separation amount d of the flange structure, and the leakage rate L of the flange structure are respectively used. R And the flange structure weight M is used as the output response value. A Kriging surrogate model is established between the output response value and the corresponding key dimension parameters of the flange structure.

[0010] S5: Construct the range of key dimensional parameters for the flange structure, establish an optimization model for the flange structure based on the Kriging proxy model established in S4, and perform optimization; if the optimization model converges, the optimal solution or a better solution for the flange structure is obtained; if the optimization model does not converge, return to S4 to add sampling points and update the Kriging proxy model until the optimization model converges.

[0011] Preferably, prior to S1, the method further includes:

[0012] The flange structure is simplified by modeling, a parametric model is established, and all dimensional parameters of the flange structure are determined.

[0013] Preferably, in step S2, the flange structure consists of a first flange and a second flange;

[0014] The applied loads include medium pressure and temperature loads;

[0015] The boundary conditions are: the sealing end faces of the first flange and the second flange are in frictional contact, and the end faces of the first flange and the second flange away from the sealing surface are subject to fixed constraints.

[0016] Preferably, after the applied load and boundary conditions are used for strength analysis, the method further includes:

[0017] Extract the maximum equivalent stress S1 of the flange structure, and the force F acting on the end face of the first flange or the second flange away from the sealing ring.

[0018] Preferably, the step of setting the material properties of all components of the flange structure, applying loads and boundary conditions to perform a flange structure sealing performance analysis specifically includes:

[0019] Set the material properties of the sealing rings and bolts / nuts in the flange structure;

[0020] Set the material properties of the first flange and the second flange according to the material properties set in S2.

[0021] Preferably, in S3, the applied load includes medium pressure, conduit force, and bolt preload.

[0022] The force applied by the conduit is the force F applied by the end face of the first flange or the second flange away from the sealing ring, which is applied to the end face of the corresponding flange away from the sealing surface.

[0023] The formula for calculating bolt preload is: In the formula, F' is the bolt preload in N; T is the bolt torque in N·mm; k is the torque coefficient, ranging from 0.18 to 0.21; and d' is the bolt diameter in mm.

[0024] The boundary conditions are: frictional contact between the sealing ring and the corresponding flange, between the first flange and the second flange, and between the bolt and nut and the corresponding flange; and a fixed constraint is applied to the end face of the first flange away from the sealing surface.

[0025] Preferably, in S3, the flange structure leakage rate L R The calculation formula is

[0026]

[0027] In the formula,

[0028] L R - Leakage rate, in Pa·m 3 / s;

[0029] η - The ratio of the dynamic viscosity of the medium to the dynamic viscosity of helium at room temperature (1 MPa);

[0030] P - Medium pressure, unit: MPa;

[0031] P d -Minimum stress of the sealing ring, in MPa;

[0032] A q N q - represents the gasket coefficient, obtained by fitting experimental data.

[0033] Preferably, the Kriging proxy model expression is as follows:

[0034] K(x)=f T (x)β+z(x)

[0035] In the formula,

[0036] K(x) - Response value;

[0037] A set of key dimensional parameters for the x-flange structure, in mm;

[0038] f T (x) - Regression basis function, f T (x)={f1(x),f2(x),L,f n (x)};

[0039] β-regression coefficient, β T ={β1,β2,L,β n};

[0040] z(x) has a mean of 0 and a variance of σ. 2 The random distribution error.

[0041] Preferably, in step S5, the flange structure optimization model uses the maximum equivalent stress S1 of the flange structure, the maximum separation amount d of the flange structure, and the leakage rate L of the flange structure. R As constraints, the objective function is the weight M of the flange structure;

[0042] The expression for the flange structure optimization model is as follows:

[0043] min M(x)

[0044]

[0045] In the formula,

[0046] M(x) - Flange structure weight in the flange structure optimization model;

[0047] S1(x) - Maximum equivalent stress of flange structure in flange structure optimization model, in MPa;

[0048] L R (x) - Flange structure leakage rate in the flange structure optimization model, in Pa·m 3 / s;

[0049] d(x) - The maximum separation amount of the flange structure in the flange structure optimization model, in mm;

[0050] A set of key dimensional parameters for the x-flange structure, in mm;

[0051] [σ b - Allowable stress of flange structure, in MPa;

[0052] [L] - Allowable leakage rate of flange structure, in Pa·m 3 / s;

[0053] [d] - Permissible separation allowance for flange structure, in mm;

[0054] x L x U - The upper and lower limits of key dimensional parameters of the flange structure, in mm.

[0055] A second aspect of the present invention discloses a flange structure optimization system for a liquid rocket engine, the system comprising:

[0056] The first modeling unit is used to perform S1: sampling all dimensional parameters of the flange structure, performing modeling based on the sample points, and obtaining the flange structure weight M; wherein, the flange structure includes: a first flange, a second flange, a sealing ring, and bolts and nuts; different dimensional parameters correspond to different flange structure weights M;

[0057] The first analysis unit is used to perform S2: perform the first finite element mesh generation on the flange structure, set the material properties of some components of the flange structure, apply loads and boundary conditions to perform strength analysis, and use the maximum equivalent stress S1 of the flange structure as the target response value to screen out several key dimension parameters that have the greatest impact on the maximum equivalent stress S1 of the flange structure.

[0058] The second analysis unit is used to perform S3: performing a second finite element mesh generation on the flange structure, setting the material properties of all components of the flange structure, applying loads and boundary conditions to perform a flange structure sealing performance analysis, using the maximum separation amount d and the flange structure leakage rate L of the flange structure as the parameters. R As the target response value, the maximum separation amount d of the flange structure and the leakage rate L of the flange structure are selected respectively. R Several key dimensional parameters that have an impact;

[0059] The second modeling unit is used to execute S4: based on the sampled points, using the maximum equivalent stress S1 of the flange structure, the maximum separation amount d of the flange structure, and the leakage rate L of the flange structure, respectively. R And the flange structure weight M is used as the output response value. A Kriging surrogate model is established between the output response value and the corresponding key dimension parameters of the flange structure.

[0060] The third modeling unit is used to execute S5: construct the range of key dimensional parameters of the flange structure, establish an optimization model of the flange structure based on the Kriging proxy model and perform optimization; if the optimization model converges, the optimal solution or a better solution of the flange structure is obtained; if the optimization model does not converge, return to S4 to add sampling points and update the Kriging proxy model until the optimization model converges.

[0061] Through one or more technical solutions of the present invention, the present invention has the following beneficial effects or advantages:

[0062] This invention discloses a method and system for optimizing the flange structure of a liquid rocket engine. By comprehensively considering the influencing factors of flange structure strength and sealing performance, the key dimensional parameters that have the primary impact on flange structure strength and sealing performance are selected. Based on these parameters, a Kriging proxy model is constructed to replace the complex finite element simulation model, and a flange structure optimization model is established to optimize the flange structure design, thereby reducing the computational cost of flange structure optimization and improving optimization efficiency.

[0063] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0064] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0065] In the attached diagram:

[0066] Figure 1 The diagram illustrates the implementation process of a method for optimizing the flange structure of a liquid rocket engine according to an embodiment of the present invention.

[0067] Figure 2 A schematic diagram of a liquid rocket engine flange structure optimization system according to an embodiment of the present invention is shown. Detailed Implementation

[0068] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0069] See Figure 1 This invention discloses a method for optimizing the flange structure of a liquid rocket engine, specifically including the following steps:

[0070] S1: Sample all dimensional parameters of the flange structure, perform modeling based on the sample points, and obtain the geometric model of the flange structure.

[0071] In this embodiment, the flange structure includes: a first flange, a second flange, a sealing ring, and bolts and nuts.

[0072] Before S1, the flange structure is simplified by modeling, a parametric model is established, and all dimensional parameters of the flange structure are determined. Specifically, parametric modeling is a model built and analyzed using parameters (variables) rather than numbers. New models can be built and analyzed by simply changing the parameter values ​​in the model.

[0073] During parametric modeling, the length of the straight segment when modeling the first and second flanges is not less than [a certain value]. In the formula, R represents the flange flow channel radius in mm; t represents the thickness of the straight section of the flange in mm; the inner diameter of the first and second flanges remains constant during parametric modeling, while the outer diameter is changed. The sealing ring can be a metal or non-metallic ring, such as a flexible graphite ring, and the specific material properties are determined based on the flange structure and actual requirements.

[0074] During the modeling process of S1, experimental design methods such as Latin hypercube sampling can be used to sample all dimensional parameters of the flange structure to establish a geometric model of the flange structure. It is worth noting that flange structure geometric models with different dimensional parameters have different flange structure weights M, thereby enabling the determination of the flange structure weight M under different dimensional parameters.

[0075] S2: Perform the first finite element mesh generation on the geometric model of the flange structure, set the material properties of some components of the flange structure, apply loads and boundary conditions to perform strength analysis, and use the maximum equivalent stress S1 of the flange structure as the target response value. Through sensitivity analysis, select several key dimensional parameters that have the greatest impact on the maximum equivalent stress S1 of the flange structure.

[0076] In this embodiment, the flange structure consists of a first flange and a second flange. When applying loads and boundary conditions, the applied loads include medium pressure and temperature loads; the boundary conditions are: the sealing end faces of the first and second flanges are in frictional contact, and fixed constraints are applied to the end faces of the first and second flanges away from the sealing surface. After strength analysis, this embodiment extracts the maximum equivalent stress S1 of the flange structure according to requirements, and the force F acting on the end face of the first flange (or second flange) away from the sealing ring. This end face force F is a resultant force, containing forces in several directions. Flange structures with different dimensional parameters have different maximum equivalent stresses S1 during strength analysis. Therefore, the maximum equivalent stress S1 of the flange structure can be used as the target response value. Sensitivity analysis is used to screen out several key dimensional parameters that have the greatest impact on the maximum equivalent stress S1 of the flange structure, thereby finding the correlation between the maximum equivalent stress S1 and the key dimensional parameters. It is worth noting that in this embodiment, when screening key dimensional parameters, they are sorted according to their influence, and the top-ranked key dimensional parameters are selected. The force F acting on the end face of the first flange (or second flange) away from the sealing ring is used in the sealing analysis, which will be introduced in detail later.

[0077] S3: Perform a second finite element mesh generation on the flange structure geometric model, set the material properties of all components of the flange structure, apply loads and boundary conditions to perform a flange structure sealing performance analysis, using the maximum separation d and the flange structure leakage rate L as the parameters. R As the target response value, sensitivity analysis was used to screen out the maximum separation amount d and the leakage rate L of the flange structure. R Several key dimensional parameters that have an impact.

[0078] In this embodiment, the flange structure comprises a first flange, a second flange, a sealing ring, and bolts and nuts. When setting the material properties of all components of the flange structure, the material properties of the sealing ring and bolts / nuts are also set. For example, the sealing ring may be a metallic or non-metallic sealing ring, with the specific material properties determined based on the flange structure and actual requirements. The material properties of the first and second flanges are set according to the material properties set in S2 to ensure consistency in material properties during strength and sealing analyses, avoiding the impact of material property errors.

[0079] Furthermore, when applying loads and boundary conditions, the applied loads include medium pressure, conduit force, and bolt preload. Specifically, the sealing analysis load step in S3 includes two steps. The first step is the preload condition, where bolt preload is applied. The formula for calculating the bolt preload is as follows: In the formula, F' is the bolt preload (N), T is the bolt torque (N·mm), k is the torque coefficient (0.18~0.21), and d' is the bolt diameter (mm). The second step involves applying the medium pressure and the force exerted by the conduit. The force exerted by the conduit is the force F exerted on the end face of the first or second flange away from the sealing ring, applied to the end face of the corresponding flange away from the sealing surface. The boundary conditions are: frictional contact between the sealing ring and the corresponding flange, between the first and second flanges, and between the bolts and nuts and the corresponding flanges; and a fixed constraint is applied to the end face of the first flange away from the sealing surface.

[0080] After the sealing analysis, the maximum separation amount d of the flange structure, the minimum contact stress S1 of the sealing ring, the weight M of the flange structure, and the leakage rate L of the flange structure will be obtained. R Parameters such as the maximum separation amount d of the flange structure and the leakage rate L of the flange structure will be selected according to the requirements in this embodiment. R As the target response value, sensitivity analysis was used to screen out the maximum separation amount d and the leakage rate L of the flange structure. R Several key dimensional parameters are affected to determine the maximum separation amount d and the leakage rate L of the flange structure. R The correlation between key dimensional parameters and those with significant impact. It is worth noting that in this embodiment, key dimensional parameters are sorted according to their magnitude of influence when screening, and the top-ranked key dimensional parameters are selected.

[0081] Among them, the flange structure leakage rate L R The calculation formula is

[0082] L R =ηA q PP d Nq

[0083] In the formula,

[0084] L R - Leakage rate, in Pa·m 3 / s;

[0085] η - The ratio of the dynamic viscosity of the medium to the dynamic viscosity of helium at room temperature (1 MPa);

[0086] P - Medium pressure, unit: MPa;

[0087] P d -Minimum stress of the sealing ring, in MPa;

[0088] A q N q - represents the gasket coefficient, obtained by fitting experimental data.

[0089] S1 to S3 are specific implementation schemes for sensitivity analysis of flange structures. By combining factors such as strength and sealing performance, several key dimensional parameters that affect the sensitivity of flange structures are determined in order to be used in the subsequent construction of the Kriging surrogate model. This makes the Kriging surrogate model closely related to the sensitivity of the flange structure, thereby optimizing the flange structure in a targeted manner.

[0090] S4: Based on the sampled points, the maximum equivalent stress S1 of the flange structure, the maximum separation amount d of the flange structure, and the leakage rate L of the flange structure are respectively used. R The flange structure weight M is used as the output response value, and a Kriging surrogate model is established between the output response value and the corresponding key dimension parameters of the flange structure.

[0091] In this embodiment, the sampling points are the sample points corresponding to several key dimensional parameters in S2-S3. In addition, the maximum equivalent stress S1, the maximum separation amount d of the flange structure, and the flange structure leakage rate L are also included. R Both the flange structure weight M and the flange structure weight M have their own Kriging proxy models.

[0092] The Kriging proxy model expression is:

[0093] K(x)=f T (x)β+z(x)

[0094] In the formula,

[0095] K(x) - Response value;

[0096] A set of key dimensional parameters for the x-flange structure, in mm;

[0097] f T (x) - Regression basis function, f T (x)={f1(x),f2(x),L,f n (x)};

[0098] β-regression coefficient, β T ={β1,β2,L,β n};

[0099] z(x) has a mean of 0 and a variance of σ. 2 The random distribution error.

[0100] S5: Construct the range of key dimensional parameters for the flange structure, establish an optimization model for the flange structure based on the Kriging surrogate model established in S4, and perform optimization. If the optimization model converges, the optimal or near-optimal solution for the flange structure is obtained. If the optimization model does not converge, return to S4 to add sampling points and update the Kriging surrogate model until the optimization model converges.

[0101] In this embodiment, the flange structure optimization model uses the maximum equivalent stress S1 of the flange structure, the maximum separation amount d of the flange structure, and the leakage rate L of the flange structure. R As constraints, the objective function is the weight M of the flange structure;

[0102] Specifically, the expression for the flange structure optimization model is as follows:

[0103] min M(x)

[0104]

[0105] In the formula,

[0106] M(x) - Flange structure weight in the flange structure optimization model;

[0107] S1(x) - Maximum equivalent stress of flange structure in flange structure optimization model, in MPa;

[0108] L R (x) - Flange structure leakage rate in the flange structure optimization model, in Pa·m 3 / s;

[0109] d(x) - The maximum separation amount of the flange structure in the flange structure optimization model, in mm;

[0110] A set of key dimensional parameters for the x-flange structure, in mm;

[0111] [σ b - Allowable stress of flange structure, in MPa;

[0112] [L] - Allowable leakage rate of flange structure, in Pa·m 3 / s;

[0113] [d] - Allowable separation of flange structure, in mm;

[0114] x L ,x U - The upper and lower limits of key dimensional parameters of the flange structure, in mm.

[0115] In this embodiment, the constraints and objective function in the flange structure optimization model are represented using the Kriging surrogate model, thus eliminating the need for strength analysis and sealing analysis during the optimization process. This reduces the computational cost of flange structure optimization and improves optimization efficiency.

[0116] Based on the same inventive concept as the foregoing embodiments, the following embodiments disclose a liquid rocket engine flange structure optimization system, see below. Figure 2 The system includes:

[0117] The first modeling unit 201 is used to perform S1: sampling all dimensional parameters of the flange structure, performing modeling based on the sample points, and obtaining a geometric model of the flange structure; wherein, the flange structure includes: a first flange, a second flange, a sealing ring, and bolts and nuts; the geometric models of flange structures with different dimensional parameters have different flange structure weights M;

[0118] The first analysis unit 202 is used to perform S2: perform the first finite element mesh generation on the geometric model of the flange structure, set the material properties of some components of the flange structure, apply loads and boundary conditions to perform strength analysis, and use the maximum equivalent stress S1 of the flange structure as the target response value, and screen out several key dimension parameters that have the greatest impact on the maximum equivalent stress S1 of the flange structure through sensitivity analysis.

[0119] The second analysis unit 203 is used to perform S3: performing a second finite element mesh generation on the geometric model of the flange structure, setting the material properties of all components of the flange structure, applying loads and boundary conditions to perform flange structure sealing analysis, using the maximum separation amount d and the flange structure leakage rate L of the flange structure as the parameters. R As the target response value, sensitivity analysis was used to screen out the maximum separation amount d and the leakage rate L of the flange structure. R Several key dimensional parameters that have an impact;

[0120] The second modeling unit 204 is used to execute S4: based on the sampled sample points, using the maximum equivalent stress of the flange structure S1, the maximum separation amount of the flange structure d, and the leakage rate of the flange structure L respectively. R And the flange structure weight M is used as the output response value. A Kriging proxy model is established between the output response value and the corresponding key dimension parameters of the flange structure.

[0121] The third modeling unit 205 is used to execute S5: construct the range of key dimensional parameters of the flange structure, establish an optimization model of the flange structure based on the Kriging proxy model established in S4 and perform optimization; if the optimization model converges, the optimal solution or a better solution of the flange structure is obtained; if the optimization model does not converge, return to S4 to add sampling points to update the Kriging proxy model until the optimization model converges.

[0122] This invention discloses a method and system for optimizing the flange structure of a liquid rocket engine. By comprehensively considering the factors affecting the strength and sealing performance of the flange structure, the method selects the dimensional parameters that have a significant impact on the strength and sealing performance of the flange structure, and constructs a Kriging proxy model to replace the complex finite element simulation model. This establishes a flange structure optimization model and optimizes the flange structure design, thereby reducing the computational cost of flange structure optimization and improving optimization efficiency.

[0123] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0124] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for optimizing the flange structure of a liquid rocket engine, characterized in that, The method includes: S1: Sampling is performed on all dimensional parameters of the flange structure, and modeling is carried out based on the sampled points to obtain the geometric model of the flange structure; wherein, the flange structure includes: a first flange, a second flange, a sealing ring, and bolts and nuts; the geometric models of the flange structure with different dimensional parameters have different flange structure weights. M ; S2: Perform a first finite element mesh generation on the geometric model of the flange structure, set the material properties of some components of the flange structure, apply loads and boundary conditions to perform strength analysis, and use the maximum equivalent stress of the flange structure as the finite element mesh. Assuming the target response value, sensitivity analysis is used to screen out the maximum equivalent stress on the flange structure. Several key dimensional parameters that have an impact; S3: Perform a second finite element mesh generation on the geometric model of the flange structure, set the material properties of all components of the flange structure, apply loads and boundary conditions to perform a flange structure sealing performance analysis, and determine the maximum separation amount of the flange structure. Flange structure leakage rate Assuming the target response value, sensitivity analysis was used to screen out the maximum separation amount for the flange structure. Flange structure leakage rate Several key dimensional parameters that have an impact; S4: Based on the aforementioned sample points, take the maximum equivalent stress of the flange structure as the reference. Maximum separation amount of flange structure Flange structure leakage rate and flange structural weight M To output the response value, a Kriging surrogate model is established between the output response value and the corresponding critical dimensional parameters of the flange structure. S5: Construct the key dimensional parameter range for the flange structure, establish an optimization model for the flange structure based on the Kriging surrogate model established in S4, and perform optimization; if the optimization model converges, the optimal or near-optimal solution for the flange structure is obtained; if the optimization model does not converge, return to S4 to add sampling points and update the Kriging surrogate model until the optimization model converges; in S5, the flange structure optimization model is based on the maximum equivalent stress of the flange structure. Maximum separation amount of flange structure Flange structure leakage rate As a constraint, the weight of the flange structure is used. M The objective function is; the expression for the flange structure optimization model is as follows: In the formula, Flange structure weight in the flange structure optimization model; The maximum equivalent stress of the flange structure in the flange structure optimization model, in MPa; The flange structure leakage rate in the flange structure optimization model is expressed in Pa·m. 3 / s; The maximum separation of the flange structure in the flange structure optimization model, in mm; A set of key dimensional parameters for flange structure, in mm; Allowable stress of flange structure, in MPa; Allowable leakage rate of flange structure, in Pa·m 3 / s; Permissible separation allowance for flange structure, in mm; The upper and lower limits of key dimensional parameters of the flange structure, in mm.

2. The method as described in claim 1, characterized in that, Prior to S1, the method further includes: The flange structure is simplified by modeling, a parametric model is established, and all dimensional parameters of the flange structure are determined.

3. The method as described in claim 1, characterized in that, In S2, the flange structure consists of the first flange and the second flange; The applied loads include medium pressure and temperature loads; The boundary conditions are: the sealing end faces of the first flange and the second flange are in frictional contact, and the end faces of the first flange and the second flange away from the sealing surface are subject to fixed constraints.

4. The method as described in claim 1, characterized in that, After performing strength analysis based on the applied loads and boundary conditions, the method further includes: Extract the maximum equivalent stress of the flange structure The force acting on the first flange or the second flange away from the sealing ring end face F .

5. The method as described in claim 1, characterized in that, The process of setting the material properties of all components of the flange structure, applying loads and boundary conditions, and performing a flange structure sealing performance analysis specifically includes: Set the material properties of the sealing rings and bolts / nuts in the flange structure; Set the material properties of the first flange and the second flange according to the material properties set in S2.

6. The method as described in claim 4, characterized in that, In S3, the applied load includes medium pressure, conduit force, and bolt preload. The force applied to the conduit is the force applied to the end face of the first flange or the second flange away from the sealing ring. F It is applied to the end face of the corresponding flange that is furthest from the sealing surface; The formula for calculating bolt preload is: In the formula, - Bolt preload, in units of ; - Bolt torque, in units of ; The torque coefficient ranges from 0.18 to 0.

21. Bolt diameter, in mm; The boundary conditions are: frictional contact between the sealing ring and the corresponding flange, between the first flange and the second flange, and between the bolt and nut and the corresponding flange; and a fixed constraint is applied to the end face of the first flange away from the sealing surface.

7. The method as described in claim 1, characterized in that, In S3, the flange structure leakage rate The calculation formula is In the formula, Leakage rate, in Pa·m 3 / s; The ratio of the dynamic viscosity of the medium to the dynamic viscosity of helium at room temperature (1 MPa); Medium pressure, in MPa; Minimum stress of the sealing ring, in MPa; The sealing gasket coefficient is obtained by fitting experimental data.

8. The method as described in claim 1, characterized in that, The Kriging proxy model expression is: In the formula, Response value; A set of key dimensional parameters for flange structure, in mm; Regression basis function, ; Regression coefficient, ; The mean is 0 and the variance is The random distribution error.

9. A liquid rocket engine flange structure optimization system, characterized in that, The system includes: The first modeling unit is used to perform S1: sampling all dimensional parameters of the flange structure, performing modeling based on the sampled points, and obtaining a geometric model of the flange structure; wherein, the flange structure includes: a first flange, a second flange, a sealing ring, and bolts and nuts; flange structure geometric models with different dimensional parameters have different flange structure weights. M ; The first analysis unit is used to perform S2: performing a first finite element mesh generation on the geometric model of the flange structure, setting the material properties of some components of the flange structure, applying loads and boundary conditions to perform strength analysis, and using the maximum equivalent stress of the flange structure as the finite element mesh generation. Assuming the target response value, sensitivity analysis is used to screen out the maximum equivalent stress on the flange structure. Several key dimensional parameters that have an impact; The second analysis unit is used to perform S3: performing a second finite element mesh generation on the flange structure geometric model, setting the material properties of all components of the flange structure, applying loads and boundary conditions to perform a flange structure sealing performance analysis, with the maximum separation of the flange structure as the criterion. Flange structure leakage rate Assuming the target response value, sensitivity analysis was used to screen out the maximum separation amount for the flange structure. Flange structure leakage rate Several key dimensional parameters that have an impact; The second modeling unit is used to perform S4: based on the sampled points, respectively using the maximum equivalent stress of the flange structure... Maximum separation amount of flange structure Flange structure leakage rate and flange structural weight M To output the response value, a Kriging surrogate model is established between the output response value and the corresponding critical dimensional parameters of the flange structure. The third modeling unit is used to execute S5: constructing the range of key dimensional parameters for the flange structure, establishing an optimization model for the flange structure based on the Kriging surrogate model established in S4, and performing optimization; if the optimization model converges, the optimal or near-optimal solution for the flange structure is obtained; if the optimization model does not converge, it returns to S4 to add sampling points and update the Kriging surrogate model until the optimization model converges; in S5, the flange structure optimization model is based on the maximum equivalent stress of the flange structure. Maximum separation amount of flange structure Flange structure leakage rate As a constraint, the weight of the flange structure is used. M The objective function is; the expression for the flange structure optimization model is as follows: In the formula, Flange structure weight in the flange structure optimization model; The maximum equivalent stress of the flange structure in the flange structure optimization model, in MPa; The flange structure leakage rate in the flange structure optimization model is expressed in Pa·m. 3 / s; The maximum separation of the flange structure in the flange structure optimization model, in mm; A set of key dimensional parameters for flange structure, in mm; Allowable stress of flange structure, in MPa; Allowable leakage rate of flange structure, in Pa·m 3 / s; Permissible separation allowance for flange structure, in mm; The upper and lower limits of key dimensional parameters of the flange structure, in mm.

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