A method for quantitatively evaluating sealing performance of a flared pipe connecting pair considering temperature load action

Abstract

The application discloses a kind of quantitative evaluation methods of sealing performance of flared pipe connection pair considering temperature load action, and relates to the field of flared pipe joint structure optimization.Can give consideration to the sealing performance quantitative evaluation method of flared pipe connection pair of multiple physical field and multiple scales with the efficiency of calculation precision, to improve the scientificity and effectiveness of sealing reliability design and evaluation of flared pipe joint under the action of temperature load.S1, establish the finite element model of flared pipe connection pair;S2, simulate and analyze the temperature field distribution and mechanical properties of flared pipe connection pair under the action of temperature load;S3, establish the leakage rate calculation method of flared pipe connection pair.Provide a powerful quantitative tool for the rapid evaluation and design iteration needs in engineering, can improve the scientificity and effectiveness of sealing design reliability and prediction in key fields such as aviation hydraulic system and pipeline connection.

Description

Technical Field

[0001] This invention relates to the field of flared pipe joint structure optimization. Background Technology

[0002] Flared pipe fittings are critical components in aircraft hydraulic system piping connections. Temperature loads can cause deformation of various parts of the fitting, which is one of the factors leading to leaks and ultimately hydraulic system failure or even paralysis. Therefore, it is necessary to accurately assess the sealing performance of flared pipe fittings under temperature loads during the design phase as a reference for improving the reliability of the hydraulic piping system.

[0003] The current evaluation of the sealing performance of pipe connections under temperature loads mainly relies on macroscopic indicators, such as effective sealing surface width, average contact pressure, and maximum contact pressure. Some studies have used heat transfer models and finite element simulations to obtain the distribution and variation trend of contact pressure at the sealing surface, thereby analyzing changes in sealing performance. Subsequent research has further obtained the critical contact pressure and its distribution based on the microscopic contact behavior of the sealing interface, using the effective sealing surface width as an evaluation indicator. Other researchers have extracted real microscopic morphology information from the sealing surface to construct models that accurately represent the geometric characteristics of microscopic leakage channels, thus precisely simulating microscopic leakage. In addition, in engineering practice, experimental methods such as pressure decay tests are used to determine or measure leakage.

[0004] However, existing methods still have limitations. First, assessment methods based on macroscopic indicators often only provide qualitative descriptions such as changes in contact pressure and effective sealing surface width to assist in analyzing the trend of sealing performance changes. A practical and accurate link cannot be established between macroscopic indicators and leakage rate, which directly reflects sealing performance; that is, changes in macroscopic indicators cannot directly and accurately reflect changes in leakage rate. Second, multi-scale numerical calculations from macroscopic to microscopic levels under multi-physics coupling cannot be achieved, and a quantitative mapping relationship from macroscopic to microscopic levels has not been established to obtain accurate leakage rate values. Furthermore, quantitative assessment methods for sealing performance under temperature loads are lacking. Finally, at the engineering application level, high-precision models constructed based on the microscopic morphology of the actual sealing surface are complex in modeling methods and extremely costly in computation. Experimental methods are similarly complex, time-consuming, and costly, making it difficult to meet the needs of rapid evaluation and design iteration in practical engineering.

[0005] In summary, existing methods have significant shortcomings in terms of quantitative analysis, multi-physics coupling, macro-micro mapping, and engineering practical efficiency when evaluating the sealing performance of flared pipe connection pairs under temperature loads. Summary of the Invention

[0006] To address the above problems, this invention proposes a quantitative evaluation method for the sealing performance of flared pipe joints that considers the effects of temperature load. This method balances computational accuracy and efficiency, and considers multiple physical fields and scales to improve the scientific rigor and effectiveness of the design and evaluation of the sealing reliability of flared pipe joints under temperature load.

[0007] The technical solution of the present invention includes the following steps:

[0008] S1. Establish the finite element model of the flared pipe connection pair;

[0009] S2. Simulation analysis of the temperature field distribution and mechanical properties of the flared pipe connection under temperature load, to obtain the specific contact stress values ​​and changes of contact stress on the sealing surface under different oil or air temperatures;

[0010] S3. Establish a method for calculating the leakage rate of flared pipe connection pairs. The calculation results of the nodes at the same circumferential position in the finite element model reflect the calculation results of the entire sealing surface. The macroscopic contact stress under temperature load is linked with the microscopic porosity and the compression of the sealing surface to achieve quantitative calculation of the leakage rate.

[0011] S4. After obtaining the leakage rate, the sealing performance under temperature load is quantitatively evaluated. The leakage rate directly reflects the current leakage degree of the sealing surface. The smaller the value, the higher the sealing reliability; the larger the value, the greater the leakage risk.

[0012] In step S2, the thermal boundary conditions for the flared pipe connection are applied by selecting the surfaces of the inner and outer wall units of the pipe and applying convection heat transfer boundary conditions to them respectively.

[0013] The convective heat transfer coefficient h is calculated using the following formula:

[0014]

[0015] in, Indicates the thermal conductivity of the medium. As a characteristic size parameter, the Nusselt number Nu represents the ratio of convective heat transfer flux to conductive heat transfer flux through a fluid layer of characteristic length, and represents the dimensionless temperature gradient of the fluid on the wall surface.

[0016] The temperature field distribution of the flared pipe connection is obtained by applying a temperature load to the oil or air; the temperature field distribution of the flared pipe connection is obtained by changing the temperature of the oil or air and the convective heat transfer coefficient at different temperatures.

[0017] Considering the actual working conditions of the pipe joint, when performing thermo-mechanical coupling simulation, it is also necessary to consider the pre-tightening effect of the outer nut, the fixed support of the non-contact end of the straight pipe joint, and the oil pressure on the inner wall of the pipe.

[0018] Under the complete load and boundary conditions described above, the specific contact stress values ​​and changes in contact stress of the sealing surface under different oil or air temperatures were obtained.

[0019] When establishing the leakage rate calculation method in step S3, the contact surface between the flared conduit and the straight-through pipe joint is the sealing interface, whereby... This is the compression amount of the sealing surface, determined based on the corresponding contact stress. P is the critical height of the sealing interface in the initial contact state; P is the pressure difference between the inside and outside of the sealing surface. Since the external environmental pressure of the flared pipe connection is much smaller than the internal oil pressure, P is approximated as the magnitude of the oil pressure when taking its value.

[0020] Based on Darcy's law, the equation of motion for fluids in porous media is established. Darcy's law is expressed as:

[0021]

[0022] In the formula, V is the seepage velocity; Where K is the fluid viscosity, which is affected by temperature; K is the permeability of the sealing surface. The divergence symbol is p; p is the pressure field function inside the sealing surface.

[0023] For the problem of unidirectional Newtonian fluid flow in porous media, permeability depends only on the geometric characteristics of the porous media and is independent of the fluid properties; the permeability expression considering the tortuosity of the sealed interface is as follows: As shown:

[0024]

[0025] In the formula, Indicates tortuosity, which is related to the porosity of the sealing surface; Knudsen's empirical coefficient, with a value of 5.5; R is the porosity of the sealing surface; R is the equivalent radius of the micro-protrusion at the sealing interface.

[0026] According to the principle of conservation of mass, when leakage occurs at the sealing surface, the mass of fluid flowing out of the tiny pores of the sealing surface per unit time is equal to the mass of fluid flowing out per unit time, that is:

[0027]

[0028] In the formula, Where G is the fluid density and G is the volume of the sealing surface;

[0029] Since the volume, fluid density, and porosity of the sealing surface do not change with time, the left side of the equation is 0. Therefore, the equation is... After substitution, it can be further expressed as:

[0030]

[0031] In the formula, p is the pressure field function inside the sealing surface.

[0032] In step S3, to apply the leakage rate model based on Darcy's law to the conical sealing surface and enable it to accurately describe the pressure distribution and oil flow on the conical sealing surface, a spherical coordinate system is established. Thus, for the pressure field function The following transformation relationship from Cartesian coordinates to spherical coordinates can be constructed:

[0033]

[0034] After coordinate transformation, the expression for the Laplace operator of the pressure field function in spherical coordinates can be obtained:

[0035]

[0036] Analyzing the actual physical characteristics of the sealing surface, it is assumed that the pressure of the oil inside the flared conduit under steady flow conditions is uniformly distributed circumferentially. Due to the wide sealing surface These are variables at the micro level, therefore in The great circle tangent can be assumed to have constant oil pressure, i.e. ;

[0037] The formula To simplify, in the direction of the sphere's diameter To represent the flow of oil, we can obtain the differential equation of the pressure field function with respect to the spherical coordinates of the sealing surface in the spherical coordinate system:

[0038]

[0039] In the formula, p is the pressure field function inside the sealing surface.

[0040] Based on the boundary conditions of internal and external pressures of the sealing surface Solve the equation by integration The expression for the pressure gradient along the conical surface is obtained as follows:

[0041]

[0042] Conical sealing surface leakage rate It is the product of the seepage velocity and the cross-sectional area of ​​the sealing surface;

[0043] The conical sealing surface unfolds circumferentially into a trapezoidal strip, the area of ​​which is... for:

[0044]

[0045] In the formula, the effective sealing surface width It is at the micrometer level, therefore It is a high-order small quantity and can be ignored during calculation. item;

[0046] Then connect the flared pipe to the secondary sealing surface to reduce leakage rate. integral mean Leakage rate reflecting the overall structure:

[0047]

[0048] In the formula, the negative sign represents leakage.

[0049] The core of this invention lies in the multiphysics coupling method and the multiscale leakage rate calculation method. By establishing a finite element model of the flared pipe, analyzing the temperature field distribution and mechanical properties of the flared pipe connection under temperature load, and proposing a leakage rate calculation method that connects macroscopic and microscopic parameters, a rapid and accurate quantitative assessment of the sealing performance of the flared pipe connection under temperature load is achieved. This method comprehensively considers the multiphysics coupling effect and realizes multiscale numerical calculation from macroscopic to microscopic, overcoming the shortcomings of traditional methods that are not accurate enough in assessing sealing performance based on macroscopic indicators and have low efficiency in engineering applications. It provides a scientific basis and efficient tool for the sealing reliability design and condition assessment of pipe connection joints under high-temperature conditions such as aviation hydraulic systems.

[0050] This invention addresses the shortcomings of existing sealing performance evaluation methods in terms of quantitative analysis, multi-physics coupling, macroscopic-to-microscopic multi-scale numerical calculation, and engineering efficiency. Compared with traditional methods that rely on macroscopic indicators, this method calculates the leakage rate, which directly reflects the degree of leakage at the sealing surface, based on the relationship between macroscopic and microscopic parameters. This ensures the accuracy of the evaluation and provides a powerful quantitative tool for rapid evaluation and design iteration in engineering. It can improve the reliability of sealing design and the scientific validity and effectiveness of predictions in critical fields such as aerospace hydraulic systems. Attached Figure Description

[0051] Figure 1 This is a flowchart of the present invention;

[0052] Figure 2 A three-dimensional geometric model of a flared pipe fitting;

[0053] Figure 3 A finite element model of a flared pipe connection pair;

[0054] Figure 4 The temperature field distribution of the flared pipe connection under temperature load;

[0055] Figure 5 For the contact stress of the sealing surface under different oil or air temperatures;

[0056] Figure 6 For the physical parameters related to the sealing surface;

[0057] Figure 7 This relates the compression of the sealing surface to the contact stress.

[0058] Figure 8 The relationship between porosity and contact stress in sealing holes;

[0059] Figure 9 For the sealed surface spherical coordinate system;

[0060] Figure 10 This refers to the method for calculating the area of ​​the sealing surface;

[0061] Figure 11 Leakage rate of sealing surface under different oil temperature loads;

[0062] Figure 12 The leakage rate of the sealing surface under different air temperature loads. Detailed Implementation

[0063] To clearly illustrate the technical features of the present invention, the present invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0064] The overall concept of this invention is as follows: Figure 1 As shown, it includes the following steps:

[0065] S1. Establishment of the finite element model of the flared pipe connection pair.

[0066] Three-dimensional geometric model of flared pipe fitting, as follows Figure 2 As shown, it consists of a flared pipe, a straight pipe fitting, an outer nut, and a flat pipe nozzle. Based on the geometric model, the thread characteristics and length are simplified, and its finite element model is established as follows. Figure 3 As shown, the finite element model is meshed using 20-node hexahedral SOILD226 elements that support thermo-structure coupling analysis. Referring to the aerospace materials handbook, corresponding material parameters are assigned to each component of the finite element model. Furthermore, since some parts of the flared pipe fitting may enter the plastic deformation stage when pre-tightened, the plastic behavior of the pipe fitting component needs to be considered.

[0067] S2. Temperature field distribution and mechanical properties of flared pipe connection pairs under temperature load.

[0068] Considering only the effect of temperature load, the thermal boundary condition for the flared pipe connection is applied as follows: the surfaces of the inner and outer wall units of the pipe are selected and convective heat transfer boundary conditions are applied separately.

[0069] The convective heat transfer coefficient h is calculated using an empirical formula derived from the similarity principle:

[0070]

[0071] in, Indicates the thermal conductivity of the medium. As a characteristic dimension parameter, the Nusselt number Nu represents the ratio of convective heat transfer flux to conductive heat transfer flux through a fluid layer of characteristic length, and represents the dimensionless temperature gradient of the fluid on the wall surface.

[0072] Based on the actual working conditions of the pipeline, the temperature of the oil and air and the thermophysical properties of the oil, the convective heat transfer coefficient between the inner and outer walls can be determined.

[0073] After applying a temperature load, the temperature field distribution of the corresponding flared pipe connection can be obtained, such as Figure 4 As shown, by changing the temperature of the oil or air and the convective heat transfer coefficient, the temperature field distribution law of the flared pipe connection pair at different temperatures can be obtained.

[0074] Considering the actual working conditions of the pipe joint, the preload of the outer nut, the fixed support on the non-contact end of the straight pipe joint, and the oil pressure on the inner wall of the pipe also need to be taken into account during thermo-mechanical coupling simulation. Under the above complete load and boundary conditions, the specific contact stress values ​​and the changes in contact stress on the sealing surface under different oil or air temperatures can be obtained, such as... Figure 5 As shown.

[0075] S3. Calculation method for leakage rate of flared pipe connection pairs.

[0076] The contact surface between the flared conduit and the straight connector is a sealing interface, and its relevant physical parameters are as follows: Figure 6 As shown. Among them. The compression amount of the sealing surface can be determined based on the corresponding contact stress, such as... Figure 7 As shown; P is the critical height of the sealing interface in the initial contact state; P is the pressure difference between the inside and outside of the sealing surface. Since the external environmental pressure of the flared pipe connection is much smaller than the internal oil pressure, P can be approximated as the magnitude of the oil pressure.

[0077] Based on Darcy's law, the equation of motion for fluids in porous media is established. Darcy's law is expressed as:

[0078]

[0079] In the formula, V is the seepage velocity; Where K is the fluid viscosity, which is affected by temperature; K is the permeability of the sealing surface. is the divergence symbol; p is the pressure field function inside the sealing surface.

[0080] For the flow of unidirectional Newtonian fluids in porous media, permeability depends only on the geometric characteristics of the porous media and is independent of the fluid properties. The permeability expression considering the tortuosity of the sealed interface is as follows: As shown:

[0081]

[0082] In the formula, Indicates tortuosity, which is related to the porosity of the sealing surface; Knudsen's empirical coefficient, with a value of 5.5; For sealing holes, the relationship between porosity and contact stress is as follows: Figure 8 As shown; R is the equivalent radius of the micro-protrusion at the sealing interface.

[0083] According to the principle of conservation of mass, when leakage occurs at the sealing surface, the mass of fluid flowing out of the tiny pores of the sealing surface per unit time is equal to the mass of fluid flowing out per unit time, that is:

[0084]

[0085] In the formula, Where is the fluid density, and G is the volume of the sealing surface.

[0086] Since the volume, fluid density, and porosity of the sealing surface do not change with time, the left side of the equation is 0. Therefore, the equation is... After substitution, it can be further expressed as:

[0087]

[0088] In the formula, p is the pressure field function inside the sealing surface; to apply the leakage rate model based on Darcy's law to the conical sealing surface so that it can accurately describe the pressure distribution and oil flow of the conical sealing surface, a spherical coordinate system is established. like Figure 9 As shown. Thus, for the pressure field function The following transformation relationship from Cartesian coordinates to spherical coordinates can be constructed:

[0089]

[0090] After coordinate transformation, the expression for the Laplace operator of the pressure field function in spherical coordinates can be obtained:

[0091]

[0092] Analyzing the actual physical characteristics of the sealing surface, it is assumed that the pressure of the oil inside the flared conduit under steady flow conditions is uniformly distributed circumferentially. Due to the wide sealing surface These are variables at the micro level, therefore in The great circle tangent can be assumed to have constant oil pressure, i.e. This allows the formula to be... To simplify, in the direction of the sphere's diameter To represent the flow of oil, we can obtain the differential equation of the pressure field function with respect to the spherical coordinates of the sealing surface in the spherical coordinate system:

[0093]

[0094] In the formula, p is the pressure field function inside the sealing surface.

[0095] Based on the boundary conditions of internal and external pressures of the sealing surface Solve the equation by integration The expression for the pressure gradient along the conical surface is obtained as follows:

[0096]

[0097] Conical sealing surface leakage rate It is the product of the seepage velocity and the cross-sectional area of ​​the sealing surface.

[0098] The area calculation method for the conical sealing surface is as follows: Figure 10 As shown, the sealing surface unfolds into a trapezoidal strip along the circumference, and the area of ​​the strip is... for:

[0099]

[0100] In the formula, the effective sealing surface width It is at the micrometer level, therefore It is a high-order small quantity and can be ignored during calculation. item.

[0101] Then connect the flared pipe to the secondary sealing surface to reduce leakage rate. integral mean Leakage rate reflecting the overall structure:

[0102]

[0103] In the formula, the negative sign represents leakage.

[0104] Since the applied loads and boundary conditions are uniformly distributed circumferentially, the simulation results are also uniformly distributed circumferentially. Therefore, when extracting the data needed to calculate the leakage rate, the calculation results of the entire sealing surface can be reflected by the calculation results of the nodes at the same circumferential position in the finite element model.

[0105] Thus, by linking the macroscopic contact stress under temperature load with the microscopic porosity and the compression of the sealing surface, the leakage rate can be quantitatively calculated.

[0106] S4. Application Results.

[0107] Once the leakage rate is obtained, the sealing performance under temperature load can be quantitatively evaluated. The leakage rate directly reflects the degree of leakage at the current sealing surface; the smaller the value, the higher the sealing reliability; the larger the value, the greater the risk of leakage.

[0108] Leakage rate of sealing surface under different temperature loads, such as Figure 11 , 12 As shown. The results indicate that the increased structural temperature difference caused by rising oil temperature leads to a higher leakage rate, while the increased structural temperature difference caused by decreasing air temperature leads to a lower leakage rate. However, if only the macroscopic contact stress obtained in the second step is used to analyze the changes in sealing performance, the conclusion is that the greater the relative temperature difference between the oil and air temperatures, the greater the maximum contact pressure on the contact surface, which is beneficial to the sealing of the sealing surface. There is some conflict between these two conclusions.

[0109] Further analysis reveals that while a larger temperature difference between the inside and outside of the pipe improves the structural sealing performance of the flared pipe connection, oil leakage behavior is not solely dependent on the sealing performance of the pipe structure itself. This is because the leakage rate of the sealing surface is also related to the oil viscosity; the lower the oil viscosity, the lower the leakage resistance. Although an increase in oil temperature can improve the sealing performance of the contact surface, its impact on the leakage rate is far less significant than that of oil viscosity. Therefore, when the oil temperature rises, the leakage rate of the flared pipe connection increases substantially.

[0110] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A method for quantitatively evaluating the sealing performance of flared pipe connection pairs considering temperature load, characterized in that, Includes the following steps: S1. Establish the finite element model of the flared pipe connection pair; S2. Simulation analysis of the temperature field distribution and mechanical properties of the flared pipe connection under temperature load, to obtain the specific contact stress values ​​and changes of contact stress on the sealing surface under different oil or air temperatures; S3. Establish a method for calculating the leakage rate of flared pipe connection pairs. The calculation results of the nodes at the same circumferential position in the finite element model reflect the calculation results of the entire sealing surface. The macroscopic contact stress under temperature load is linked with the microscopic porosity and the compression of the sealing surface to achieve quantitative calculation of the leakage rate. S4. After obtaining the leakage rate, the sealing performance under temperature load is quantitatively evaluated. The leakage rate directly reflects the current leakage degree of the sealing surface. The smaller the value, the higher the sealing reliability; the larger the value, the greater the leakage risk.

2. The method for quantitatively evaluating the sealing performance of flared pipe connection pairs considering temperature load, as described in claim 1, is characterized in that... In step S2, the thermal boundary conditions for the flared pipe connection are applied by selecting the surfaces of the inner and outer wall units of the pipe and applying convection heat transfer boundary conditions to them respectively. The convective heat transfer coefficient h is calculated using the following formula: in, Indicates the thermal conductivity of the medium. As a characteristic size parameter, the Nusselt number Nu represents the ratio of convective heat transfer flux to conductive heat transfer flux through a fluid layer of characteristic length, and represents the dimensionless temperature gradient of the fluid on the wall surface. The temperature field distribution of the flared pipe connection is obtained by applying a temperature load to the oil or air; the temperature field distribution of the flared pipe connection is obtained by changing the temperature of the oil or air and the convective heat transfer coefficient at different temperatures. Considering the actual working conditions of the pipe joint, when performing thermo-mechanical coupling simulation, it is also necessary to consider the pre-tightening effect of the outer nut, the fixed support of the non-contact end of the straight pipe joint, and the oil pressure on the inner wall of the pipe. Under the complete load and boundary conditions described above, the specific contact stress values ​​and changes in contact stress of the sealing surface under different oil or air temperatures were obtained.

3. The method for quantitatively evaluating the sealing performance of flared pipe connection pairs considering temperature load, as described in claim 1, is characterized in that... When establishing the leakage rate calculation method in step S3, the contact surface between the flared conduit and the straight-through pipe joint is the sealing interface, whereby... This is the compression amount of the sealing surface, determined based on the corresponding contact stress. P is the critical height of the sealing interface in the initial contact state; P is the pressure difference between the inside and outside of the sealing surface. Since the external environmental pressure of the flared pipe connection is much smaller than the internal oil pressure, P is approximated as the magnitude of the oil pressure when taking its value. Based on Darcy's law, the equation of motion for fluids in porous media is established. Darcy's law is expressed as: In the formula, V is the seepage velocity; Where K is the fluid viscosity, which is affected by temperature; K is the permeability of the sealing surface. The divergence symbol is p; p is the pressure field function inside the sealing surface. For the problem of unidirectional Newtonian fluid flow in porous media, permeability depends only on the geometric characteristics of the porous media and is independent of the fluid properties; the permeability expression considering the tortuosity of the sealed interface is as follows: As shown: In the formula, This indicates the degree of tortuosity, which is related to the porosity of the sealing surface. Knudsen's empirical coefficient, with a value of 5.5; R is the porosity of the sealing surface; R is the equivalent radius of the micro-protrusion at the sealing interface. According to the principle of conservation of mass, when leakage occurs at the sealing surface, the mass of fluid flowing out of the tiny pores of the sealing surface per unit time is equal to the mass of fluid flowing out per unit time, that is: In the formula, Where G is the fluid density and G is the volume of the sealing surface; Since the volume, fluid density, and porosity of the sealing surface do not change with time, the left side of the equation is 0. Therefore, the equation is... After substitution, it can be further expressed as: In the formula, p is the pressure field function inside the sealing surface.

4. The method for quantitatively evaluating the sealing performance of flared pipe connection pairs considering temperature load, as described in claim 3, is characterized in that... In step S3, to apply the leakage rate model based on Darcy's law to the conical sealing surface and enable it to accurately describe the pressure distribution and oil flow of the conical sealing surface, a spherical coordinate system is established. Thus, for the pressure field function The following transformation relationship from Cartesian coordinates to spherical coordinates can be constructed: After coordinate transformation, the expression for the Laplace operator of the pressure field function in spherical coordinates can be obtained: Analyzing the actual physical characteristics of the sealing surface, it is assumed that the pressure of the oil inside the flared conduit under steady flow conditions is uniformly distributed circumferentially. Due to the wide sealing surface These are variables at the micro level, therefore in The great circle tangent can be assumed to have constant oil pressure, i.e. ; The formula To simplify, in the direction of the sphere's diameter To represent the flow of oil, we can obtain the differential equation of the pressure field function with respect to the spherical coordinates of the sealing surface in the spherical coordinate system: In the formula, p is the pressure field function inside the sealing surface.

5. The method for quantitatively evaluating the sealing performance of flared pipe connection pairs considering temperature load, as described in claim 4, is characterized in that... Based on the boundary conditions of internal and external pressures of the sealing surface Solve the equation by integration The expression for the pressure gradient along the conical surface is obtained as follows: Conical sealing surface leakage rate It is the product of the seepage velocity and the cross-sectional area of ​​the sealing surface; The conical sealing surface unfolds circumferentially into a trapezoidal strip, the area of ​​which is... for: In the formula, the effective sealing surface width It is at the micrometer level, therefore It is a high-order small quantity and can be ignored during calculation. item; Then connect the flared pipe to the secondary sealing surface to reduce leakage rate. integral mean Leakage rate reflecting the overall structure: In the formula, the negative sign represents leakage.

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