A pipeline dynamic characteristic analysis method based on fluid-solid coupling effect equivalence

Abstract

The application provides a pipeline dynamic characteristic analysis method based on fluid-solid coupling effect equivalence, and belongs to the technical field of pipeline dynamic characteristic analysis. The method comprises the following steps: S1, determining the geometric model parameters of an oil / gas pipeline to obtain first parameters; S2, determining the static / dynamic parameters of the oil / gas pipeline medium to obtain second parameters; S3, determining the mechanical parameters of equivalent spring mass blocks to obtain third parameters; S4, constructing a spring equivalent model based on the first parameters, the second parameters and the third parameters; S5, establishing a finite element calculation model considering the fluid-solid coupling effect based on the spring equivalent model; S6, outputting equivalent spring-oil / gas pipeline dynamic characteristics containing medium coupling effects based on the finite element calculation model to obtain a calculation result; and S7, designing and optimizing an oil / gas pipeline gathering scheme based on the calculation result. The application aims to solve the technical problems of relatively large calculation time, complex structure, high error rate and large workload in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of pipeline dynamic characteristic analysis technology, specifically relating to a pipeline dynamic characteristic analysis method based on fluid-structure interaction effect. Background Technology

[0002] Fluid-structure interaction (FSI) refers to the displacement, velocity, and acceleration generated when a fluid acts on the surface or interior of a solid. It is a science that studies the various behaviors of deformable solids under the action of a flow field and the influence of solid configuration on the flow field. The key characteristic of FSI is the interaction between two phases. Deformable solids will deform or move under the action of fluid loads, and the deformation or movement will in turn affect the fluid movement, thereby changing the distribution and magnitude of the fluid load. It is this interaction that will produce various FSI phenomena under different conditions.

[0003] Chinese patent application number CN201910001794.6 discloses "a method and apparatus for predicting the three-dimensional fluid-structure interaction parameter resonance response characteristics of an aviation pipeline. This method establishes a three-dimensional fluid-structure interaction dynamic model of the aviation pipeline based on relevant parameters; establishes the three-dimensional fluid-structure interaction dynamic equations of motion for the aviation pipeline based on the dynamic model; obtains a finite-dimensional matrix equation based on the dynamic equations of motion; and obtains the parameter resonance response characteristics of the aviation pipeline within a preset pulsating frequency range based on the finite-dimensional matrix equation."

[0004] In the process of obtaining the above-mentioned parametric resonance response characteristics, the resonance range can be effectively avoided and parametric resonance can be prevented, thereby improving the service life and safety of aviation transmission pipelines.

[0005] However, the aforementioned patent uses a system coupling method of fluid field and solid field for calculation, which results in relatively long calculation time, complex structure, and high error rate, thus significantly increasing the workload. Summary of the Invention

[0006] The purpose of this invention is to provide a method for analyzing the dynamic characteristics of pipelines based on the equivalent fluid-structure interaction effect. This invention aims to solve the technical problems of relatively long calculation time, complex structure, and high error rate in the prior art, which lead to a significant increase in workload.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for analyzing the dynamic characteristics of a pipeline based on the equivalent fluid-structure interaction effect includes the following steps:

[0009] S1. Determine the geometric model parameters of the oil and gas pipeline to obtain the first parameter;

[0010] S2. Determine the static / dynamic parameters of the medium in the oil and gas pipeline to obtain the second parameter;

[0011] S3. Determine the mechanical parameters of the equivalent spring mass to obtain the third parameter;

[0012] S4. Construct an equivalent spring model based on the first parameter, the third parameter, and the first parameter;

[0013] S5. Establish a finite element calculation model considering fluid-structure interaction based on the spring equivalent model;

[0014] S6. Based on the finite element calculation model, output the equivalent spring-oil and gas pipeline dynamic characteristics including the medium coupling effect to obtain the calculation results;

[0015] S7. Based on the calculation results, design and optimize the oil and gas pipeline gathering and transportation scheme. This invention aims to solve the technical problems of relatively long calculation times, complex structures, and high error rates in existing technologies, which lead to a significant increase in workload.

[0016] As a preferred embodiment of the present invention, in step S1, the first parameter includes pipe diameter, pipe material, pipe span, and pipe constraints.

[0017] In step S2, the second parameter includes medium mass, medium viscoelastic coefficient, medium flow rate, and medium fill degree;

[0018] In step S3, the third parameter includes the spring mass, the spring constant, and the number and distribution of the spring and the mass block.

[0019] As a preferred embodiment of the present invention, in step S3, the mechanical parameters of the equivalent spring mass block are calculated based on the spring smoothing method, and then the third parameter is obtained.

[0020] In a preferred embodiment of the present invention, step S3 of the spring smoothing method includes the following steps:

[0021] The smoothed position of each node is obtained by calculating the force balance equation between the spring nodes. The force balance equation is as follows:

[0022] Formula (1)

[0023] In the formula:

[0024] These are the displacements of spring node i and spring node j, respectively;

[0025] The number of nodes connected to spring node i;

[0026] Let be the elastic coefficient between spring node i and spring node j;

[0027] The spring constant is defined as:

[0028] Formula (2)

[0029] In the formula:

[0030] The Spring Constant Factor is an input value.

[0031] When the spring force reaches equilibrium, it can be calculated that:

[0032]

[0033] In the formula:

[0034] m is the number of iterations;

[0035] Once the displacement of spring node i is calculated, the mesh position is updated:

[0036] Formula (4);

[0037] Then, the spring constant, the number and distribution of springs and mass blocks are obtained, and finally the mass of the mass blocks is obtained based on the mass of the medium and the number of mass blocks.

[0038] As a preferred embodiment of the present invention, the equivalent model of the spring includes:

[0039] Pipeline equivalent module;

[0040] The spring equivalent module is provided in multiple groups, and the multiple groups of spring equivalent modules are equidistantly arranged on the inner wall of the pipe equivalent module. Each group of spring equivalent modules is provided in multiple ways, and the multiple spring equivalent modules are evenly distributed in a ring.

[0041] The number of mass block equivalent modules matches the number of spring equivalent modules, and each mass block equivalent module is located at the end of the spring equivalent module away from the pipe equivalent module.

[0042] As a preferred embodiment of the present invention, in step S5, the finite element calculation model adopts... The model, in which, The model uses fluid flow equations, which are as follows:

[0043] Formula (5)

[0044] Formula (6)

[0045] In the formula:

[0046] It is turbulent kinetic energy;

[0047] This represents the dissipation rate of turbulent kinetic energy in the fluid.

[0048] The viscosity coefficient is the turbulent viscosity coefficient.

[0049] and The Prandtl number represents the turbulent flow.

[0050] This is the turbulent kinetic energy generation term caused by the average velocity gradient;

[0051] This refers to the turbulent kinetic energy term generated by buoyancy;

[0052] The effect of compressible turbulent fluctuations;

[0053] , , , and It is a constant;

[0054] and For source terms.

[0055] As a preferred embodiment of the present invention, the fluid flow equation is obtained based on the continuity equation and the momentum equation, wherein:

[0056] The continuity equation is:

[0057] Formula (7)

[0058] In the formula:

[0059] For time;

[0060] For fluid density;

[0061] These are the fluid velocity components in each direction;

[0062] The momentum equation is:

[0063] Formula (8)

[0064] In the formula:

[0065] It is the viscous shear force tensor;

[0066] It is a volume force vector.

[0067] In a preferred embodiment of the present invention, the fluid flow equation follows a conservation principle at the fluid-structure interaction surface, and satisfies the following conditions:

[0068] Formula (9)

[0069] Formula (10)

[0070] In the formula:

[0071] This represents the shear force vector of the fluid.

[0072] The number of nodes in the fluid;

[0073] This is the shear force vector of the solid;

[0074] The number of nodes in the solid;

[0075] For the displacement of the fluid;

[0076] For the position of a solid;

[0077] The vibration equation of the overall structure is obtained based on formulas (5)-(10), and the vibration equation is:

[0078] Formula (11)

[0079] In the formula:

[0080] The mass matrix considering fluid-structure interaction effects;

[0081] The damping matrix considering fluid-structure interaction effects;

[0082] The elastic coefficient matrix is ​​used to account for fluid-structure interaction effects.

[0083] In a preferred embodiment of the present invention, step S6 includes the following steps:

[0084] S61. Based on the finite element calculation model, output the displacement response, acceleration response, and dynamic stress response, including the equivalent spring of the medium.

[0085] S62. Based on the finite element calculation model, output the natural frequency, mode shape, and damping of the equivalent spring of the medium.

[0086] Compared with the prior art, the beneficial effects of the present invention are:

[0087] This invention proposes adding a spring equivalent model to the pipeline's dynamic model. The spring equivalent module effectively simulates the mass, stiffness, and damping of the oil and gas medium. This avoids multi-physics field calculations, significantly improving computational speed. Furthermore, the established spring equivalent principle provides crucial reference value for other similar fluid-structure interaction (FSI) calculation problems. Existing technologies that consider the FSI effect between the oil and gas medium and the pipeline can more accurately describe the pipeline's dynamic response under dynamic loads. However, they neglect the FSI interaction between the oil and gas medium and the pipeline, leading to discrepancies between the seismic resistance of the pipeline structure and its ancillary facilities and actual engineering requirements, resulting in frequent pipeline structural failures. This invention, however, uses a spring equivalent model. Firstly, it considers both the FSI interaction and the fluid dynamics, as well as the inherent complexities of converting theory into solid-field calculations. Secondly, by setting the spring's elastic coefficient, it can simulate the viscoelastic hysteresis effect of the oil and gas medium. In summary, this invention offers advantages such as shorter computation time, simpler construction, negligible error rate, and significantly reduced workload. Attached Figure Description

[0088] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0089] Figure 1 This is a flowchart of a pipeline dynamic characteristic analysis method based on the fluid-structure interaction effect of the present invention.

[0090] Figure 2 This is a three-dimensional view of the spring equivalent model in the pipeline dynamic characteristic analysis method based on fluid-structure interaction effect of the present invention.

[0091] Figure 3 This is a three-dimensional cross-sectional view of the spring equivalent model in the pipeline dynamic characteristic analysis method based on fluid-structure interaction effect of the present invention.

[0092] Figure 4 This is a diagram of experimental data from Example 2 of the present invention, which is a method for analyzing the dynamic characteristics of a pipeline based on the equivalent fluid-structure interaction effect.

[0093] In the picture:

[0094] 100. Pipeline equivalent module;

[0095] 200. Spring equivalent module;

[0096] 300, equivalent module of mass block. Detailed Implementation

[0097] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0098] Example 1:

[0099] This invention provides the following technical solutions:

[0100] Please see Figure 1 A method for analyzing the dynamic characteristics of a pipeline based on the equivalent fluid-structure interaction effect includes the following steps:

[0101] S1. Determine the geometric model parameters of the oil and gas pipeline to obtain the first parameter. Specifically, the first parameter includes the pipeline diameter, pipeline material, pipeline span, and pipeline constraints.

[0102] S2. Determine the static / dynamic parameters of the medium in the oil and gas pipeline to obtain the second parameter. Specifically, the second parameter includes the medium mass, the medium viscoelastic coefficient, the medium flow velocity, and the medium filling degree.

[0103] S3. Determine the mechanical parameters of the equivalent spring-mass block to obtain the third parameter. Specifically, the third parameter includes the spring mass, the spring constant, and the number and distribution of the spring and the mass block. This step is as follows:

[0104] The mechanical parameters of the equivalent spring mass block are calculated based on the spring smoothing method, and then the third parameter is obtained.

[0105] The spring smoothing method includes the following steps:

[0106] The smoothed position of each node is obtained by calculating the force balance equation between the spring nodes. The force balance equation is as follows:

[0107] Formula (1)

[0108] In the formula:

[0109] These are the displacements of spring node i and spring node j, respectively;

[0110] The number of nodes connected to spring node i;

[0111] Let be the elastic coefficient between spring node i and spring node j;

[0112] The spring constant is defined as:

[0113] Formula (2)

[0114] In the formula:

[0115] The Spring Constant Factor is an input value.

[0116] When the spring force reaches equilibrium, it can be calculated that:

[0117]

[0118] In the formula:

[0119] m is the number of iterations;

[0120] Once the displacement of spring node i is calculated, the mesh position is updated:

[0121] Formula (4);

[0122] Then, the spring constant, the number and distribution of springs and mass blocks are obtained, and finally the mass of the mass blocks is obtained based on the mass of the medium and the number of mass blocks.

[0123] S4. Construct an equivalent model of the spring based on the first parameter, the third parameter, and the fourth parameter. For details, please refer to [link / reference]. Figure 2 and Figure 3 The equivalent model of a spring includes:

[0124] Pipeline equivalent module 100;

[0125] The spring equivalent module 200 is provided in multiple groups. The multiple groups of spring equivalent modules 200 are fixed at equal intervals on the inner wall of the pipe equivalent module 100. Each group of spring equivalent modules 200 is provided in multiple groups, and the multiple spring equivalent modules 200 are evenly distributed in a ring.

[0126] The number of mass block equivalent modules 300 matches the number of spring equivalent modules 200, and each mass block equivalent module 300 is fixed to the end of the spring equivalent module 200 away from the pipe equivalent module 100.

[0127] The spring equivalent module 200 is equivalent to "damping between the medium and the pipe";

[0128] The mass block equivalent module 300 is equivalent to "medium mass";

[0129] S5. Establish a finite element calculation model considering fluid-structure interaction based on the spring equivalent model;

[0130] S6. Based on the finite element calculation model, output the equivalent spring-oil and gas pipeline dynamic characteristics including the medium coupling effect to obtain the calculation results. This includes the following steps:

[0131] S61. Based on the finite element calculation model, output the displacement response, acceleration response, and dynamic stress response, including the equivalent spring of the medium.

[0132] S62. Output the natural frequency, mode shape, and damping of the equivalent spring based on the finite element calculation model;

[0133] Specifically, the finite element calculation model adopts The model, in which, The model uses the fluid flow equation, which is:

[0134] Formula (5)

[0135] Formula (6)

[0136] In the formula:

[0137] It is turbulent kinetic energy;

[0138] This represents the dissipation rate of turbulent kinetic energy in the fluid.

[0139] The viscosity coefficient is the turbulent viscosity coefficient.

[0140] and The Prandtl number represents the turbulent flow.

[0141] This is the turbulent kinetic energy generation term caused by the average velocity gradient;

[0142] This refers to the turbulent kinetic energy term generated by buoyancy;

[0143] The effect of compressible turbulent fluctuations;

[0144] , , , and It is a constant;

[0145] and For source terms;

[0146] The fluid flow equation is derived based on the continuity equation and the momentum equation, where:

[0147] The continuity equation is:

[0148] Formula (7)

[0149] In the formula:

[0150] For time;

[0151] For fluid density;

[0152] These are the fluid velocity components in each direction;

[0153] The momentum equation is:

[0154] Formula (8)

[0155] In the formula:

[0156] It is the viscous shear force tensor;

[0157] It is a volume force vector.

[0158] In a preferred embodiment of the present invention, the fluid flow equation follows a conservation principle at the fluid-structure interaction surface, satisfying the following conditions:

[0159] Formula (9)

[0160] Formula (10)

[0161] In the formula:

[0162] This represents the shear force vector of the fluid.

[0163] The number of nodes in the fluid;

[0164] This is the shear force vector of the solid;

[0165] The number of nodes in the solid;

[0166] For the displacement of the fluid;

[0167] For the position of a solid;

[0168] Based on formulas (5)-(10), the vibration equation of the overall structure is obtained, and the vibration equation is:

[0169] Formula (11)

[0170] In the formula:

[0171] The mass matrix considering fluid-structure interaction effects;

[0172] The damping matrix considering fluid-structure interaction effects;

[0173] The elastic coefficient matrix considering fluid-structure interaction effects;

[0174] The above Refers to the aforementioned dynamic stress response, i.e., displacement response; The first derivative of represents the velocity response; The second derivative of represents the acceleration response; since the above parameters are fixed, the natural frequency, mode shape, and damping are correspondingly determined.

[0175] S7. Design and optimize oil and gas pipeline gathering and transportation schemes based on calculation results.

[0176] Example 2:

[0177] This embodiment uses the "ANSYS WORKBENCH" software and conducts experiments based on the method of Embodiment 1:

[0178] Overview of this embodiment: An analysis is conducted on a pipe with a length of 284m, an outer diameter of 720mm, and a thickness of 14mm. The fluid used is crude oil, which flows in from one end of the pipe and out from the other end. The inlet velocity is 2m / s, and the pipe is filled with crude oil (density 889m³ / s). 3 With a viscosity coefficient of 1.06 kg / (m*s), the following experimental data were obtained:

[0179] Table 1: Experimental Data Table

[0180]

[0181] As shown in Table 1:

[0182] At the first second, the total force on the fluid coupling surface along the x-axis is 2.18e+4N, the total force along the y-axis is -2.57e+01N, and the total force along the z-axis is -7.21E-02N.

[0183] The total force on the pipe coupling surface along the x-axis is 2.18E+04N, the total force along the y-axis is 2.57E-01N, and the total force along the z-axis is -7.21E-02N.

[0184] The displacement of the pipeline coupling surface is 1.21e-05m along the x-axis, 9.80e-07m along the y-axis, and -1.23e-07m along the z-axis.

[0185] The fluid coupling surface has a x-axis displacement of 1.21e-05m, a y-axis displacement of 9.80e-07m, and a z-axis displacement of -1.22e-07m; (2.17e+04 represents 2.17 * 10^6 m). 4 -2.5e-01 means -2.5 * 10 -1 )

[0186] in:

[0187] Positive values ​​indicate that the direction is the same as the x, y, and z axes;

[0188] Negative values ​​indicate directions that are the same as or opposite to those of the x, y, and z axes;

[0189] The above experimental data has an error range of ±0.1% compared with the actual situation, that is, it fluctuates by about 0.1%. This shows that the experimental data obtained by the method provided by the present invention is particularly accurate and its error is negligible.

[0190] Based on the method of Example 1, and analyzed by Example 2, the computation time is significantly reduced, specifically:

[0191] Using traditional methods, it would take the applicant's research group 3 days to run the program to calculate the length of a 2.84-meter-long pipe;

[0192] However, by using the invention of this invention, calculating the length of a 2.84-meter pipe only requires 0.5 days of program execution time, which greatly reduces the calculation time.

[0193] The above section of this embodiment only presents partial experimental data; please refer to [the original text]. Figure 4 , Figure 4 A complete graph of experimental data;

[0194] The principle of considering the dynamic characteristics of oil and gas pipelines under fluid-structure interaction in traditional technology is to solve the dynamic equations of the structural system. The structural parameters in the dynamic direction involve mass, stiffness, and damping. Theoretically, the mass, stiffness, and damping of the oil and gas medium must be superimposed on the structural parameters of the pipeline in the form of a matrix. Theoretically, solving the dynamic equations is not a problem, but the amount of calculation is so large that it is almost impossible.

[0195] Furthermore, using the existing technology described in the background section, our research group employs a simulation method, which requires establishing the fluid field of the oil and gas medium and the solid field of the oil and gas pipeline, and determining their boundary conditions. Currently, our research group needs 3 days of program execution time to calculate a 2.84-meter-long pipeline.

[0196] Therefore, this invention proposes to add a spring equivalent model to the dynamic model of the pipeline, and use the spring equivalent module 200 to simulate the mass, stiffness and damping of the oil and gas medium. In this way, the calculation speed is greatly improved, and the established spring equivalent principle can also provide particularly important reference value for other similar fluid-structure interaction calculation problems.

[0197] Existing technologies that consider the fluid-structure interaction effect between oil and gas medium and oil and gas pipelines can more accurately describe the dynamic response characteristics of pipelines under dynamic loads. However, they neglect the fluid-structure interaction effect between oil and gas medium and oil and gas pipelines, which results in the seismic resistance of the oil and gas pipeline structure system and its ancillary facilities not meeting the requirements of actual engineering, leading to frequent damage to the pipeline structure system.

[0198] However, this invention uses a spring equivalent model, which firstly considers the fluid-structure interaction, as well as the fluid and the inherent complex theoretical calculation problem of transforming it into a solid field; secondly, by setting the elastic coefficient of the spring, the viscoelastic hysteresis effect of oil and gas media can be simulated.

[0199] In summary, this invention has a short computation time, simple structure, negligible error rate, and significantly reduced workload.

[0200] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for analyzing dynamic characteristics of a pipeline based on an equivalent fluid-structure coupling effect, characterized in that, Includes the following steps: S1. Determine the geometric model parameters of the oil and gas pipeline to obtain the first parameter; S2. Determine the static / dynamic parameters of the medium in the oil and gas pipeline to obtain the second parameter; S3. Determine the mechanical parameters of the equivalent spring mass to obtain the third parameter; S4. Construct an equivalent spring model based on the first parameter, the third parameter, and the first parameter; S5. Establish a finite element calculation model considering fluid-structure interaction based on the spring equivalent model; S6. Based on the finite element calculation model, output the equivalent spring-oil and gas pipeline dynamic characteristics including the medium coupling effect to obtain the calculation results; S7. Based on the calculation results, design and optimize the oil and gas pipeline gathering and transportation scheme; In step S1, the first parameter includes pipe diameter, pipe material, pipe span, and pipe constraints; In step S2, the second parameter includes medium mass, medium viscoelastic coefficient, medium flow rate, and medium fill degree; In step S3, the third parameter includes the spring mass, the spring constant, and the number and distribution of the spring and the mass block; In step S3, the mechanical parameters of the equivalent spring mass block are calculated based on the spring smoothing method, and then the third parameter is obtained; In step S3, the spring smoothing method includes the following steps: The smoothed position of each node is obtained by calculating the force balance equation between the spring nodes. The force balance equation is as follows: Equation (1) In the formula: respectively the displacement of spring node i and spring node j; Nj number of nodes connected to spring node i; Kij is the spring constant between spring node i and spring node j; The spring constant is defined as: In the formula: K is the spring constant factor, which is an input value; When the spring force reaches equilibrium, it can be calculated that: In the formula: m is the number of iterations; Once the displacement of spring node i is calculated, the mesh position is updated: Equation (4); Then, the spring constant, the number and distribution of springs and mass blocks are obtained, and finally the mass of the mass blocks is obtained based on the mass of the medium and the number of mass blocks. In step S4, the equivalent model of the spring includes: Pipeline equivalent module (100); A spring equivalent module (200) is provided in multiple groups. The multiple groups of spring equivalent modules (200) are equidistantly arranged on the inner wall of the pipe equivalent module (100). Each group of spring equivalent modules (200) is provided in multiple groups. The multiple spring equivalent modules (200) are evenly distributed in a ring. The number of mass block equivalent modules (300) matches the number of spring equivalent modules (200), and each mass block equivalent module (300) is respectively located at the end of the spring equivalent module (200) away from the pipe equivalent module (100); The spring equivalent module (200) is equivalent to "damping between the medium and the pipe"; The mass block equivalent module (300) is equivalent to "medium mass".

2. The method for analyzing dynamic characteristics of a pipe based on an equivalent fluid-structure coupling effect according to claim 1, characterized in that, In step S5, the finite element calculation model employs a model, wherein the model employs fluid flow equations, which are: Equation (5) Equation (6) In the formula: is the turbulent kinetic energy; is the dissipation rate of the kinetic energy of the fluid turbulence; is the turbulent viscosity coefficient; and Re is the Reynolds number; and Pr is the Prandtl number. The average velocity gradient induced turbulent energy generation term; is the turbulent kinetic energy term for buoyancy production; for the influence of compressible turbulent fluctuations; , , , and are constants; and is the source term.

3. The method of claim 2, wherein, The fluid flow equation is derived based on the continuity equation and the momentum equation, where: The continuity equation is: Equation (7) In the formula: t is time; where p is the fluid density; Vx, Vy, Vz are the fluid velocity components in the respective directions; The momentum equation is: Equation (8) In the formula: is the viscous shear stress tensor; is the volume force vector.

4. The method of claim 3, wherein, The fluid flow equation follows a conservation principle at the fluid-structure interaction surface, and satisfies the following conditions: Equation (9) Equation (10) In the formula: shear force vector of the fluid; number of nodes for the fluid; Shear force vector for solid; Number of nodes that are solid; displacement of fluid; bit that is solid; The vibration equation of the overall structure is obtained based on formulas (5)-(10), and the vibration equation is: Equation (11) In the formula: mass matrix considering fluid-structure coupling effect; a damping matrix that takes into account the fluid-structure coupling effect; The elastic coefficient matrix considering the fluid-structure coupling effect.

5. The method of claim 4, wherein, Step S6 includes the following steps: S61. Based on the finite element calculation model, output the displacement response, acceleration response, and dynamic stress response, including the equivalent spring of the medium. S62, outputting, based on the finite element calculation model, inherent frequency, mode shape diagram and damping of the medium equivalent spring.

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