Design and calculation method for mechanical seal end surface specific pressure

Abstract

The invention discloses a design and calculation method for mechanical seal end face specific pressure. The method comprises the steps that material parameters, end face morphology parameters, structural parameters and working condition parameters of dynamic and static rings of a mechanical seal are obtained; determining the maximum height and the initial porosity of the contact interface gap of the moving and static rings; determining the compression amount of a sealing interface; determining the deformation state of the sealing interface; determining a first end surface specific pressure of the sealing interface under a non-percolation critical contact condition; the second end face specific pressure of the sealing interface is determined; and according to the first end face specific pressure and the second end face specific pressure, the design range of the mechanical seal end face specific pressure is determined. By means of the method, the defect that only empirical values are relied on when mechanical sealing end face specific pressure parameters are designed in the prior art can be overcome, it can be ensured that the selected end face contact pressure is more scientific and reasonable, it can be ensured that the mechanical sealing end face does not leak, meanwhile, the wear rate of the mechanical sealing end face does not exceed the standard, and the service life is prolonged. Important guarantee is provided for zero-leakage and long-service-life operation of the mechanical sealing device.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical seals, and in particular relates to a design and calculation method for mechanical seal end face pressure ratio. Background Art

[0002] Mechanical seals are the primary shaft seals for rotating equipment such as centrifugal compressors, centrifugal pumps, and steam turbines. Their key performance parameters include leakage rate and wear life. Besides operating parameters, the most critical factor affecting mechanical seal performance is the mechanical parameter of end face pressure. Increasing the end face pressure helps reduce the porosity between the seal faces and achieve zero leakage. However, excessive seal face pressure increases wear on the end faces of the dynamic and static seals, shortening the service life of the mechanical seal.

[0003] The book "Chemical Sealing Technology" states that for pump mechanical seals, the end face pressure ratio is generally selected from 0.3 to 0.5 MPa for internal mechanical seals and 0.15 to 0.4 MPa for external mechanical seals. For media with high viscosity, the end face pressure ratio is generally selected from 0.5 to 0.7 MPa, while for materials with poor lubricity and high volatility, a lower end face pressure ratio is generally selected, typically from 0.25 to 0.45 MPa. The "Mechanical Design Manual," "Chapter 10: Lubrication and Sealing," provides end face pressure ratio ranges for mechanical seals for different media and installation methods. For a long time, the design of end face pressure ratio parameters for mechanical seals has relied on empirical values ​​from the aforementioned literature, lacking a theoretical basis and severely limiting the optimal performance of mechanical seals. Summary of the Invention

[0004] In response to the above shortcomings, the present invention aims to provide a design and calculation method for the end face pressure ratio of a mechanical seal to address the shortcomings of existing mechanical seal end face pressure ratio design methods, ensuring that the mechanical seal achieves zero leakage while meeting the requirements for the end face wear rate, thereby improving the service life and sealing performance of the mechanical seal. The specific solution is as follows:

[0005] A design and calculation method for mechanical seal end face pressure ratio, comprising the following steps:

[0006] S1. Obtaining material parameters, end surface morphology parameters, structural parameters and operating condition parameters of the dynamic and static rings of the mechanical seal;

[0007] S2. determining the maximum height and initial porosity of the contact interface gap between the moving and static rings based on the end surface morphology parameters of the moving and static rings;

[0008] S3, determining the sealing interface compression amount based on the non-percolation critical contact condition of the contact interface and the maximum height of the contact interface gap and the initial porosity in step S2;

[0009] S4. determining the deformation state of the sealing interface according to the compression amount of the sealing interface;

[0010] S5. determining a first end surface specific pressure under a non-percolation critical contact condition of the sealing interface according to the deformation state of the sealing interface;

[0011] S6. Determine the second end surface specific pressure of the sealing interface based on the material parameters of the dynamic and static rings and the critical wear rate of the mechanical seal;

[0012] S7. Determine the design range of the mechanical seal end face pressure ratio based on the first end face pressure ratio and the second end face pressure ratio.

[0013] In this application, the dynamic and static rings are a general term for both the dynamic ring and the static ring.

[0014] Specifically, the material parameters of the dynamic and static rings include the dynamic ring elastic modulus E1, the static ring elastic modulus E2, the dynamic ring material Poisson's ratio υ1, the static ring material Poisson's ratio υ2, the static ring wear coefficient k, the static ring hardness H, the dynamic ring yield limit σ1 and the static ring yield limit σ2;

[0015] The end surface morphology parameters of the dynamic and static rings include the dynamic ring fractal dimension D1, the static ring fractal dimension D2, the dynamic ring scale coefficient G1, the static ring scale coefficient G2, the maximum height R of the dynamic ring surface profile y1 Maximum height R of the static ring surface profile y2 ;

[0016] The structural parameters of the dynamic and static rings include the outer radius R of the sealing surface o With inner radius R i ;

[0017] The operating parameters of the dynamic and static rings include the spindle speed n.

[0018] Specifically, in step S2, the maximum height of the contact interface gap is represented by h, which is calculated using formula (1):

[0019] h=0.746×(R y1 +R y2 ) (1)

[0020] The initial porosity is expressed as φ0, which is calculated using formula (2):

[0021]

[0022] Where D is the equivalent fractal dimension of the dynamic and static rings, a Lm is the base area of ​​the largest micro-protrusion on the contact interface, l is the base diameter of the outline of the largest micro-protrusion on the contact interface, and a is the contact area of ​​the micro-protrusion.

[0023] D、a Lm and l are calculated using formula (21):

[0024]

[0025] Where G is the equivalent scale coefficient of the dynamic and static rings, and G is calculated using formula (22):

[0026]

[0027] Specifically, in step S3, the non-percolation critical contact condition of the contact interface means that after pressure loading, the porosity of the contact interface of the dynamic and static rings reaches the critical porosity, and the critical porosity is represented by φ, and φ=0.312; the porosity after pressure loading is represented by φ, and the compression of the sealing interface is represented by δ, which is calculated using formula (3):

[0028]

[0029] Where φ0 is the initial porosity of the contact interface.

[0030] The above-mentioned pressure loading refers to the state in which the pressure generated by the sealing medium is loaded on the dynamic and static rings when the mechanical seal is working.

[0031] Specifically, in step S4, the deformation state of the sealing interface is divided into elastic deformation, elastoplastic deformation and plastic deformation. The specific steps for determining the deformation state of the sealing interface according to the compression amount of the sealing interface are as follows:

[0032] S401, calculate the critical compression of elastic deformation and plastic deformation of the sealing interface, the critical compression of elastic deformation adopts δ ec Indicates that δ ec Calculate using formula (4):

[0033]

[0034] Where E is the equivalent elastic modulus of the dynamic and static rings, σ y is the equivalent yield limit of the dynamic and static rings, G is the equivalent scale coefficient of the dynamic and static rings; E, σ y Specifically, the calculation is performed using formula (41):

[0035]

[0036] The critical compression of plastic deformation is δ pc Indicates that δ pc Calculate using formula (5):

[0037]

[0038] Among them, e is a natural constant;

[0039] S402, δ and δ ec and δ pcFor comparison, when δ≤δ ec , the sealing interface undergoes elastic deformation, when δ ec ≤δ≤δ pc , the sealing interface undergoes elastic-plastic deformation, when δ pc ≤δ, plastic deformation occurs on the sealing interface.

[0040] Specifically, in step S5, the first end surface pressure ratio adopts p cmin Indicates that p cmin Calculate using formula (6):

[0041]

[0042] Where a is the contact area of ​​the micro-convex body, a ec is the critical contact area of ​​elastic deformation of the micro-convex body, a pc is the critical contact area of ​​the micro-convex body for plastic deformation, E is the equivalent elastic modulus of the dynamic and static rings, G is the equivalent scale coefficient of the dynamic and static rings, a, a ec with a pc Specifically, the calculation is performed using formula (61):

[0043]

[0044] Specifically, in step S6, the critical wear rate of the mechanical seal is expressed by γ, γ = 0.02 mm / 100 h, and the second end surface specific pressure is expressed by p cmax Indicates that p cmax Calculate using formula (7):

[0045]

[0046] Where v is the sliding velocity of the sealing surface, and v is calculated using formula (71):

[0047]

[0048] When the design calculation method in this application is used to design and calculate the mechanical seal end face contact pressure, the first end face pressure ratio of the mechanical seal is first determined based on the non-percolation critical contact condition of the contact interface, and then the second end face pressure ratio of the mechanical seal is determined based on the wear rate requirement of the mechanical seal. Finally, the design range of the mechanical seal end face pressure ratio is determined based on the size of the two. This application can change the drawbacks of relying solely on empirical values ​​when designing mechanical seal end face pressure ratio parameters. It can ensure that the selected end face contact pressure is more scientific and reasonable, and can not only ensure that the mechanical seal end face does not leak, but also ensure that the wear rate of the mechanical seal end face does not exceed the standard, providing an important guarantee for the mechanical seal device to achieve zero leakage and long life operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The figure is a flow chart of the design and calculation method of the mechanical seal end face pressure ratio in this application. DETAILED DESCRIPTION

[0050] The following is a detailed description of the design and calculation method of the mechanical seal end face pressure ratio in this application. Figure 1 , the design calculation method includes the following steps:

[0051] S1. Obtain the material parameters, end surface morphology parameters, structural parameters and operating condition parameters of the dynamic and static rings of the mechanical seal.

[0052] In this embodiment, the dynamic and static ring is a general term for both the dynamic ring and the static ring.

[0053] The material parameters of the dynamic and static rings include the dynamic ring elastic modulus E1, the static ring elastic modulus E2, the dynamic ring material Poisson's ratio υ1, the static ring material Poisson's ratio υ2, the static ring wear coefficient k, the static ring hardness H, the dynamic ring yield limit σ1 and the static ring yield limit σ2;

[0054] The end surface morphology parameters of the dynamic and static rings include the dynamic ring fractal dimension D1, the static ring fractal dimension D2, the dynamic ring scale coefficient G1, the static ring scale coefficient G2, the maximum height R of the dynamic ring surface profile y1 Maximum height R of the static ring surface profile y2 ;

[0055] The structural parameters of the dynamic and static rings include the outer radius R of the sealing surface o With inner radius R i ;

[0056] The operating parameters of the dynamic and static rings include the spindle speed n.

[0057] S2. Determine the maximum height and initial porosity of the contact interface gap between the moving and static rings based on the end surface morphology parameters of the moving and static rings.

[0058] The maximum height of the contact interface gap is represented by h, which is calculated using formula (1):

[0059] h=0.746×(R y1 +R y2 ) (1)

[0060] The initial porosity is expressed as φ0, which is calculated using formula (2):

[0061]

[0062] Where D is the equivalent fractal dimension of the dynamic and static rings, a Lm is the base area of ​​the largest micro-protrusion on the contact interface, l is the base diameter of the outline of the largest micro-protrusion on the contact interface, and a is the contact area of ​​the micro-protrusion.

[0063] D、a Lm and l are calculated using formula (21):

[0064]

[0065] Where G is the equivalent scale coefficient of the dynamic and static rings, which is calculated using formula (22):

[0066]

[0067] S3. Determine the sealing interface compression amount based on the non-percolation critical contact condition of the contact interface and the maximum height of the contact interface gap and the initial porosity in step S2.

[0068] The non-percolation critical contact condition of the contact interface refers to the porosity of the contact interface of the dynamic and static rings reaching the critical porosity after pressure loading. The critical porosity is represented by φ, and φ = 0.312. The porosity after pressure loading is represented by φ, and the compression of the sealing interface is represented by δ, which is calculated using formula (3):

[0069]

[0070] Where φ0 is the initial porosity of the contact interface.

[0071] The above-mentioned pressure loading refers to the state in which the pressure generated by the sealing medium is loaded on the dynamic and static rings when the mechanical seal is working.

[0072] S4. Determine the deformation state of the sealing interface according to the compression amount of the sealing interface.

[0073] The deformation state of the sealing interface is divided into elastic deformation, elastoplastic deformation and plastic deformation. The specific steps for determining the deformation state of the sealing interface according to the compression amount of the sealing interface are as follows:

[0074] S401, calculate the critical compression of elastic deformation and plastic deformation of the sealing interface, the critical compression of elastic deformation adopts δ ec Indicates that δ ec Calculate using formula (4):

[0075]

[0076] Where E is the equivalent elastic modulus of the dynamic and static rings, σ y is the equivalent yield limit of the dynamic and static rings, E, σ y Specifically, the calculation is performed using formula (41):

[0077]

[0078] The critical compression of plastic deformation is δpc Indicates that δ pc Calculate using formula (5):

[0079]

[0080] Among them, e is a natural constant.

[0081] S402, δ and δ ec and δ pc For comparison, when δ≤δ ec , the sealing interface undergoes elastic deformation, when δ ec ≤δ≤δ pc , the sealing interface undergoes elastic-plastic deformation, when δ pc ≤δ, plastic deformation occurs on the sealing interface.

[0082] S5. Determine the first end surface specific pressure under the non-percolation critical contact condition of the sealing interface according to the deformation state of the sealing interface.

[0083] The first end surface pressure ratio is p cmin Indicates that p cmin Calculate using formula (6):

[0084]

[0085] Where a is the contact area of ​​the micro-convex body, a ec is the critical contact area of ​​elastic deformation of the micro-convex body, a pc is the critical contact area of ​​micro-convex plastic deformation, a, a ec with a pc Specifically, the calculation is performed using formula (61):

[0086]

[0087] S6. Determine the second end surface specific pressure of the sealing interface based on the material parameters of the dynamic and static rings and the critical wear rate of the mechanical seal.

[0088] In the present application, the sealing surfaces of the dynamic ring and the static ring are both smooth. Due to the high hardness of the dynamic ring and the high hardness of the static ring, when the dynamic ring and the static ring rotate relative to each other, the sealing surface of the static ring will be worn first, resulting in a wear amount. The ratio of the wear amount to time is the wear rate; the wear rate standard specified in the "Technical Conditions for Mechanical Seals" is 0.02mm / 100h. When the wear rate is less than 0.02mm / 100h, it indicates that the mechanical seal meets the wear standard. When the wear rate is greater than 0.02mm / 100h, it indicates that the mechanical seal does not meet the wear standard.

[0089] The critical wear rate of the mechanical seal is expressed by γ, γ = 0.02 mm / 100 h, and the second end surface specific pressure in step S6 is expressed by pcmax Expressed, use formula (7) to calculate:

[0090]

[0091] Where v is the sliding velocity of the sealing surface, and v is calculated using formula (71):

[0092]

[0093] S7. Determine the design range of the mechanical seal end face pressure ratio based on the first end face pressure ratio and the second end face pressure ratio.

[0094] The following is a calculation of the specific pressure of a specific mechanical seal end face:

[0095] S1. Obtain the material parameters, end surface morphology parameters, structural parameters, and operating condition parameters of the dynamic and static rings of the mechanical seal. The material parameters and end surface morphology parameters of the dynamic and static rings of the mechanical seal are shown in Table 1, and the structural parameters and operating condition parameters of the dynamic and static rings of the mechanical seal are shown in Table 2.

[0096] Table 1 Material parameters and end surface morphology parameters of the dynamic and static rings of mechanical seals

[0097]

[0098]

[0099] Table 2 Structural parameters and operating parameters of the dynamic and static rings of mechanical seals

[0100]

[0101] S2. Determine the maximum height and initial porosity of the equivalent contact interface gap between the moving and static rings based on the end surface morphology parameters of the moving and static rings.

[0102] The maximum height R of the dynamic ring surface profile in Table 1 y1 =0.28, Maximum height of static ring surface profile R y2 =2.13Substitute into formula (1)

[0103] In: h = 0.746 × (R y1 +R y2 )(1)

[0104] The maximum height of the contact interface gap between the fixed, dynamic and static rings is obtained as h = 1.79786 μm;

[0105] The initial porosity φ0 is calculated using formula (2):

[0106]

[0107] Where D is the equivalent fractal dimension of the dynamic and static rings, aLm is the base area of ​​the largest micro-convex body on the contact interface, and l is the outline base diameter of the largest micro-convex body on the contact interface. Lm and l can be calculated using formula (21):

[0108]

[0109] Where G is the equivalent scale coefficient of the dynamic and static rings, and G is calculated using formula (22):

[0110]

[0111] Substitute the dynamic ring end face scale coefficient G1 and the static ring end face scale coefficient G2 in Table 1 into formula (22) to obtain the equivalent scale coefficient G of the dynamic and static rings; substitute the dynamic ring end face fractal dimension D1 and the static ring end face fractal dimension D2 in Table 1 into formula (21) to obtain the equivalent fractal dimension D of the dynamic and static rings; substitute the equivalent fractal dimension D of the dynamic and static rings, the equivalent scale coefficient G of the dynamic and static rings and the maximum height h of the contact interface gap between the dynamic and static rings into formula (21) to obtain the outline base diameter l of the largest micro-protrusion on the contact interface; substitute the outline base diameter l of the largest micro-protrusion on the contact interface into formula (21) to obtain the base area a of the largest micro-protrusion on the contact interface Lm .

[0112] Finally, the equivalent fractal dimension D of the dynamic and static rings and the base area a of the largest micro-convex body on the contact interface are Lm Substituting the base diameter l of the largest micro-protrusion at the contact interface into formula (2), we obtain the initial porosity φ0 = 0.83.

[0113] S3. Determine the sealing interface compression amount based on the non-percolation critical contact condition of the contact interface, the maximum height of the contact interface gap in step S2, and the initial porosity.

[0114] Calculate δ using formula (3):

[0115]

[0116] Substituting φ = 0.312, initial porosity φ0 = 0.83, and the maximum height of the contact interface gap between the dynamic and static rings h = 1.798 μm into formula (3), the sealing interface compression δ = 1.354 × 10 -6 m.

[0117] S4, determining the deformation state of the sealing interface according to the compression amount of the sealing interface, specifically comprising the following steps:

[0118] S401, calculate the critical compression of elastic deformation and plastic deformation of the sealing interface, the critical compression of elastic deformation adopts δ ec Indicates that δ ecCalculate using formula (4):

[0119]

[0120] Where E is the equivalent elastic modulus of the dynamic and static rings, σ y is the equivalent yield limit of the dynamic and static rings, E, σ y Specifically, the calculation is performed using formula (41):

[0121]

[0122] Substitute the dynamic ring elastic modulus E1, static ring elastic modulus E2, dynamic ring Poisson's ratio υ1, static ring Poisson's ratio υ2, dynamic ring yield limit σ1, static ring yield limit σ2 in Table 1 into formula (41) to obtain the equivalent elastic modulus E of the dynamic and static rings and the equivalent yield limit σ of the dynamic and static rings. y The equivalent fractal dimension D of the dynamic and static ring, the equivalent scale coefficient G of the dynamic and static ring, the contour base diameter l of the largest micro-convex body of the contact interface, the equivalent elastic modulus E of the dynamic and static ring and the equivalent yield limit σ of the dynamic and static ring are calculated. y Substituting into formula (4), we can obtain the critical compression of elastic deformation δ ec =7.243×10 -12 m.

[0123] The critical compression of plastic deformation is δ pc Indicates that δ pc Calculate using formula (5):

[0124]

[0125] The equivalent fractal dimension D of the dynamic and static ring, the equivalent scale coefficient G of the dynamic and static ring, the outline base diameter l of the largest micro-convex body of the contact interface, the equivalent elastic modulus E of the dynamic and static ring and the equivalent yield limit σ of the dynamic and static ring are calculated. y Substituting into formula (4), we can obtain the critical compression of plastic deformation δ pc =1.425×10 -6 m.

[0126] S402, δ and δ ec and δ pc For comparison, when δ≤δ ec , the sealing interface undergoes elastic deformation, when δ ec ≤δ≤δ pc , the sealing interface undergoes elastic-plastic deformation, when δ pc ≤δ, plastic deformation occurs on the sealing interface.

[0127] Set δ = 1.354 × 10 -6 m, δ ec =7.243×10 -12 m, δpc =1.425×10 -6 m, and found that δ ec ≤δ≤δ pc , it means that elastic-plastic deformation occurs at the sealing interface.

[0128] S5. Determine the first end surface specific pressure p under the non-percolation critical contact condition of the sealing interface according to the deformation state of the sealing interface. cmin .p cmin Calculate using formula (6):

[0129]

[0130] Where a is the contact area of ​​the micro-convex body, a ec is the critical contact area of ​​elastic deformation of the micro-convex body, a pc is the critical contact area of ​​micro-convex plastic deformation, a, a ec with a pc Calculate using formula (61):

[0131]

[0132] Substitute the sealing interface compression δ, the equivalent scale factor G of the dynamic and static rings, and the base diameter l of the largest micro-convex body on the contact interface into formula (61) to obtain the micro-convex body contact area a; the equivalent yield limit σ of the dynamic and static rings is y , the equivalent elastic modulus E of the dynamic and static ring, the equivalent scale factor G of the dynamic and static ring, the equivalent fractal dimension D of the dynamic and static ring, and the contour base diameter l of the largest micro-convex body on the contact interface are substituted into formula (61) to obtain the critical contact area a of the micro-convex body elastic deformation ec and the critical contact area a for plastic deformation of the micro-convex body pc .

[0133] Then the equivalent yield limit σ of the dynamic and static rings y , the equivalent elastic modulus E of the dynamic and static rings, the equivalent scale factor G of the dynamic and static rings, the equivalent fractal dimension D of the dynamic and static rings, the contour base diameter l of the largest micro-convex body on the contact interface, the contact area a of the micro-convex body, and the critical contact area a of the elastic deformation of the micro-convex body ec and the critical contact area a for plastic deformation of the micro-convex body pc Substituting into formula (6), we can get the first end surface pressure p cmin =1.771MPa.

[0134] S6. Determine the second end surface specific pressure p of the sealing interface based on the material parameters of the dynamic and static rings and the critical wear rate of the mechanical seal. cmax .

[0135] When the dynamic ring and the static ring rotate relative to each other, the sealing surface of the static ring will wear first, and the wear amount will be generated. The ratio of this wear amount to time is the wear rate. 0.02mm / 100h is the wear rate standard specified in the "Technical Conditions for Mechanical Seals". When the wear rate is less than 0.02mm / 100h, it means that the mechanical seal meets the wear standard. When the wear rate is greater than 0.02mm / 100h, it means that the mechanical seal does not meet the wear standard. The critical wear rate is expressed by γ, γ = 0.02mm / 100h, and the second end face specific pressure p cmax Calculate using formula (7):

[0136]

[0137] Where v is the sliding velocity of the sealing surface, and v is calculated using formula (71):

[0138]

[0139] The inner diameter R of the sealing surface in Table 2 i , Sealing surface outer diameter R o , spindle speed n into formula (71) to obtain the sliding speed v of the sealing surface; then substitute the sliding speed v of the sealing surface, critical wear rate γ, static ring wear coefficient k in Table 1, and static ring hardness H into formula (7) to obtain the second end face specific pressure p cmax =5.682MPa.

[0140] S7. Determine the design range of the mechanical seal end face pressure ratio based on the first end face pressure ratio and the second end face pressure ratio.

[0141] In this embodiment, the first end surface specific pressure p cmin =1.771MPa, the second end surface pressure p cmax =5.682MPa, and the control range of the end face pressure ratio is 1.771~5.682MPa, which can not only achieve zero leakage of mechanical seal, but also ensure that the wear rate of the sealing end face meets the requirements.

Claims

1. A design and calculation method for mechanical seal end face pressure ratio, characterized in that: The steps include: S1. Obtaining material parameters, end surface morphology parameters, structural parameters and operating condition parameters of the dynamic and static rings of the mechanical seal; S2. determining the maximum height and initial porosity of the contact interface gap between the moving and static rings based on the end surface morphology parameters of the moving and static rings; S3, determining the sealing interface compression amount based on the non-percolation critical contact condition of the contact interface and the maximum height of the contact interface gap and the initial porosity in step S2; S4. determining the deformation state of the sealing interface according to the compression amount of the sealing interface; S5. determining a first end surface specific pressure under a non-percolation critical contact condition of the sealing interface according to the deformation state of the sealing interface; S6. Determine the second end surface specific pressure of the sealing interface based on the material parameters of the dynamic and static rings and the critical wear rate of the mechanical seal; S7. Determine the design range of the mechanical seal end face pressure ratio based on the first end face pressure ratio and the second end face pressure ratio.

2. The design calculation method according to claim 1, characterized in that: The material parameters of the dynamic and static rings include the dynamic ring elastic modulus E1, the static ring elastic modulus E2, the dynamic ring material Poisson's ratio υ1, the static ring material Poisson's ratio υ2, the static ring wear coefficient k, the static ring hardness H, the dynamic ring yield limit σ1 and the static ring yield limit σ2; The end surface morphology parameters of the dynamic and static rings include the dynamic ring fractal dimension D1, the static ring fractal dimension D2, the dynamic ring scale coefficient G1, the static ring scale coefficient G2, the maximum height R of the dynamic ring surface profile y1 Maximum height R of the static ring surface profile y2 ; The structural parameters of the dynamic and static rings include the outer radius R of the sealing surface o With inner radius R i ; The operating parameters of the dynamic and static rings include the spindle speed n.

3. The design calculation method according to claim 1, characterized in that: In step S2, the maximum height of the contact interface gap is represented by h, which is calculated using formula (1): h=0.746×(R y1 +R y2 ) (1) The initial porosity is expressed as φ0, which is calculated using formula (2): Where D is the equivalent fractal dimension of the dynamic and static rings, a Lm is the base area of ​​the largest micro-protrusion on the contact interface, l is the base diameter of the outline of the largest micro-protrusion on the contact interface, and a is the contact area of ​​the micro-protrusion.

4. The design calculation method according to claim 1, characterized in that: In step S3, the non-percolation critical contact condition of the contact interface means that after pressure loading, the porosity of the contact interface of the dynamic and static rings reaches the critical porosity, and the critical porosity is represented by φ, and φ=0.312; the porosity after pressure loading is represented by φ, and the compression of the sealing interface is represented by δ, which is calculated using formula (3): Where φ0 is the initial porosity of the contact interface.

5. The design calculation method according to claim 1, characterized in that: In step S4, the deformation state of the sealing interface is divided into elastic deformation, elastoplastic deformation and plastic deformation. The specific steps for determining the deformation state of the sealing interface according to the compression amount of the sealing interface are as follows: S401, calculate the critical compression of elastic deformation and plastic deformation of the sealing interface, the critical compression of elastic deformation adopts δ ec Indicates that δ ec Calculate using formula (4): Where E is the equivalent elastic modulus of the dynamic and static rings, σ y is the equivalent yield limit of the dynamic and static rings, G is the equivalent scale coefficient of the dynamic and static rings; The critical compression of plastic deformation is δ pc Indicates that δ pc Calculate using formula (5): Among them, e is a natural constant; S402, δ and δ ec and δ pc For comparison, when δ≤δ ec , the sealing interface undergoes elastic deformation, when δ ec ≤δ≤δ pc , the sealing interface undergoes elastic-plastic deformation, when δ pc ≤δ, plastic deformation occurs on the sealing interface.

6. The design calculation method according to claim 1, characterized in that: In step S5, the first end surface pressure ratio is p cmin Indicates that p cmin Calculate using formula (6): Where a is the contact area of ​​the micro-convex body, a ec is the critical contact area of ​​elastic deformation of the micro-convex body, a pc is the critical contact area of ​​the micro-convex body for plastic deformation, E is the equivalent elastic modulus of the dynamic and static rings, and G is the equivalent scale coefficient of the dynamic and static rings.

7. The design calculation method according to claim 1, characterized in that: In step S6, the critical wear rate of the mechanical seal is expressed by γ, γ = 0.02 mm / 100 h, and the second end surface pressure is expressed by p cmax Indicates that p cmax Calculate using formula (7): Where v is the sliding velocity of the sealing surface.

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