Method for calculating time-domain mixed lubrication characteristics of sliding bearing in deep sea high-pressure environment

Abstract

The invention relates to a method for calculating time-domain mixed lubrication characteristics of a sliding bearing in a deep-sea high-pressure environment, and provides a new calculation method for solving the engineering practical problem that a shaft and a bearing friction pair are usually in a mixed lubrication state and have very strong time-varying characteristics when a deep-sea aircraft is under low-speed and heavy-load conditions. The method can effectively solve the problem that the lubricating contact state of the ship shaft and the bearing in the deep-sea high-pressure environment is very strong in time-varying characteristic, can master the lubricating contact characteristic between the shaft and the bearing in real time, and has important guiding significance for the optimization design of the lubricating characteristic of the bearing.

Description

Technical Field

[0001] The present invention relates to the technical field of simulation calculation of lubrication and friction characteristics of sliding bearings for ship propulsion shafting, and particularly to a calculation method for time-domain mixed lubrication characteristics of sliding bearings under deep-sea high-pressure environment. Background Art

[0002] In the deep sea, there are not only extremely large reserves of resources such as oil, natural gas, manganese nodules, and combustible ice, but also the deep sea has an extremely prominent military strategic position. Therefore, the deep sea is a key area for resource development and military competition among countries in the world in the 21st century. Deep-sea vehicles play an important role in the fields of national defense security, marine resource exploration, environmental monitoring, etc. As one of the key components of the propulsion system of deep-sea vehicles, the water-lubricated stern bearing may have increased friction between the shaft and the bearing under the comprehensive influence of the deep-sea high-pressure environment, and it is extremely easy to generate abnormal friction vibration noise, seriously affecting the comfort, reliability, and stealth of deep-sea vehicles.

[0003] Under low-speed and heavy-load conditions of deep-sea vehicles, the friction pair between the shaft and the bearing is usually in a mixed lubrication state where fluid lubrication, elastohydrodynamic lubrication, and dry friction coexist simultaneously. The mixed lubrication characteristics are the comprehensive manifestation of the characteristics of various lubricating films. The proportion of various lubricating films on the contact surface is related to the friction interface morphology and working conditions. The propulsion shafting of deep-sea vehicles is affected by various impacts and periodic excitation forces during actual operation. During the friction process, the proportion and distribution of various lubricating films are constantly changing. Therefore, the mixed lubrication characteristics have strong time-variability. Therefore, establishing a calculation method for the time-domain mixed lubrication characteristics between the shaft and the bearing under the deep-sea high-pressure environment is convenient for mastering the lubrication contact characteristics between the shaft and the bearing, and has important significance for the efficient lubrication and low-noise optimization design of the bearing.

[0004] In the aspect of mixed lubrication of water-lubricated bearings, extensive theoretical and experimental studies have been carried out. However, the research on the time-domain mixed lubrication characteristics between the shaft and the bearing under the deep-sea high-pressure environment is still insufficient. Summary of the Invention

[0005] The applicant of the present invention aims at the above-mentioned disadvantages in the existing production technology, and provides a calculation method for the time-domain mixed lubrication characteristics of sliding bearings under the deep-sea high-pressure environment, so as to effectively solve the problem that the lubrication contact state between the ship shaft and the bearing under the deep-sea high-pressure environment has strong time-variability, and can master the lubrication contact characteristics between the shaft and the bearing in real time, which has important guiding significance for the optimization design of the bearing lubrication characteristics.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A calculation method for the time-domain mixed lubrication characteristics of sliding bearings under the deep-sea high-pressure environment includes the following operation processes:

[0008] S1: Determine the parameters of input shaft and bearing geometry, lubrication medium, speed, hydrostatic pressure, and surface morphology;

[0009] S2: Input the external load of the journal at the initial moment;

[0010] S3: According to the water film thickness equation h(θ) = C + ecos(θ-ψ) + δ B (θ,z,p)+h j (θ,z), assuming the initial water film thickness, C is the initial clearance, e is the journal eccentricity, θ is the circumferential coordinate, ψ is the offset angle, δ B is the elastic deformation of the bearing shell, h j is the groove depth;

[0011] S4: Iterative solution of the steady-state Reynolds average equation based on the finite difference method

[0012]

[0013] To obtain the water film pressure, R in the equation B is the bearing radius, φ θ and φ z is the pressure flow factor, φ s is the shear flow factor, U is the linear velocity of the axis, η is the viscosity of water, h T is the gap between the two surfaces, the gap between the two rough surfaces h T Relationship with nominal clearance h φ c is the contact factor;

[0014] S5: Calculate the contact pressure between the shaft and the bearing surface based on the asperity contact model;

[0015] S6: Reference the elastic deformation equation of Winkler bearing Calculate the elastic deformation of the bearing shell, p in the equation sum is the sum of deep sea hydrostatic pressure, water film pressure and asperity contact pressure, t is the thickness of rubber lining, E is the elastic modulus of bearing, ν is Poisson's ratio;

[0016] S7: Determine whether the load balance equation converges;

[0017] S8: After convergence, the calculation results are output and the mixed lubrication calculation of the shaft and bearing under the external load at the next moment is entered.

[0018] Its further technical solution is:

[0019] By ensuring that the steady-state mixed lubrication contact force of the bearing is balanced with the external load at each moment, the calculation of the time-domain mixed lubrication characteristics of the shaft and bearing is realized.

[0020] It can calculate the influence of different bearing specific pressures, rotational speeds, groove forms, and viscosity parameters of lubricating media on the mixed lubrication characteristics of bearings under the deep-sea high-pressure environment.

[0021] It can identify the time-domain friction excitation force between the shaft and the bearing, and through Fourier transform, it can identify the spectral characteristics of the friction excitation force.

[0022] In S2, define the time interval dt for solving the calculation, and discretize the external load on the journal.

[0023] In S7, if the load balance equation does not converge, adjust the eccentricity and then adjust the film thickness, and enter the next iterative calculation until convergence.

[0024] The beneficial effects of the present invention are as follows:

[0025] (1) Based on the steady-state Reynolds-averaged equation considering the coupling interface roughness, taking into account the contact action of the shaft and bearing asperities, and introducing the Winkler elastic deformation model to calculate the elastic deformation of the bearing bush under the deep-sea high-pressure environment, it can effectively balance the calculation accuracy and solution time;

[0026] (2) By ensuring the balance between the steady-state mixed lubrication contact force of the bearing and the external load at each moment, the calculation of the time-domain mixed lubrication characteristics of the shaft and the bearing is realized;

[0027] (3) The present invention can calculate the influence of parameters such as different bearing specific pressures, rotational speeds, groove forms, and viscosities of lubricating media on the mixed lubrication characteristics of bearings under the deep-sea high-pressure environment, and is applicable to the optimal design of bearing lubrication characteristics;

[0028] (4) The present invention can identify the time-domain friction excitation force between the shaft and the bearing, and through Fourier transform, it can identify the spectral characteristics of the friction excitation force, which can be used for the optimal design of bearing friction noise.

[0029] (5) Aiming at the engineering practical problem that the friction pair between the shaft and the bearing of deep-sea vehicles is usually in a mixed lubrication state and has strong time-variation under low-speed heavy-load conditions, the present invention proposes a calculation method for the time-domain mixed lubrication characteristics of the shaft and the bearing under the deep-sea high-pressure environment. Description of the Drawings

[0030] Figure 1 It is the schematic diagram of the mixed lubrication contact between the shaft and the bearing and the coordinate system (1) of the present invention under the deep-sea environment.

[0031] Figure 2 It is the schematic diagram of the mixed lubrication contact between the shaft and the bearing and the coordinate system (2) of the present invention under the deep-sea environment.

[0032] Figure 3It is the calculation flow chart of the time-domain mixed lubrication characteristics of the sliding bearing under the deep-sea high-pressure environment of the present invention.

[0033] Figure 4 It is the time-domain frictional force between the shaft and the bearing under the action of a certain sinusoidal periodic unbalanced force of the present invention (rotational speed: 30 revolutions per minute).

[0034] Figure 5 It is the frictional force spectrum between the shaft and the bearing under the action of a certain sinusoidal periodic unbalanced force of the present invention (rotational speed: 30 revolutions per minute, ordinate reference value).

[0035] Figure 6 It is the contour map of the water film pressure distribution of the present invention (t = 10s).

[0036] Figure 7 It is the contour map of the contact pressure distribution of asperities of the present invention (t = 10s)

[0037] Figure 8 It is the elastic deformation diagram of the bearing bush of the present invention (deep-sea hydrostatic pressure: 20 MPa). Specific embodiments

[0038] The following combines the drawings to illustrate the specific embodiments of the present invention.

[0039] A calculation method for the time-domain mixed lubrication characteristics of a sliding bearing under a deep-sea high-pressure environment described in this embodiment includes the following operation processes:

[0040] 101: Input parameters such as the geometry of the shaft and the bearing, lubricating medium, rotational speed, hydrostatic pressure, surface topography, etc.;

[0041] 102: Define the time interval dt for solving the calculation, discretize the time-domain external load received by the journal, and input the external load of the journal at the initial moment;

[0042] 103: According to the water film thickness equation h(θ) = C + ecos(θ - ψ) + δ B (θ,z,p) + h j (θ,z), assume the initial water film thickness. In the equation, C is the initial clearance, e is the eccentricity of the journal, θ is the circumferential coordinate, ψ is the attitude angle, δ B is the elastic deformation of the bearing bush, and h j is the groove depth;

[0043] 104: Iteratively solve the steady Reynolds-averaged equation based on the finite difference method to obtain the water film pressure. In the equation, R B is the bearing radius, φ θ and φ z are the pressure flow factors, φ s is the shear flow factor, U is the linear velocity of the shaft rotation, η is the viscosity of water, and h Tis the gap between two surfaces, and the gap h between two rough surfaces T The relationship with the nominal gap h φ c is the contact factor;

[0044] 105: Calculate the contact pressure between the shaft and the bearing surface based on the asperity contact model;

[0045] 106: Refer to the elastic deformation equation of the Winkler bearing bush Calculate the elastic deformation of the bearing bush. In the equation, p sum is the sum of the deep-sea hydrostatic pressure, the water film pressure and the asperity contact pressure, t is the thickness of the rubber lining, E is the elastic modulus of the bearing bush, ν is the Poisson's ratio;

[0046] 107: Judge whether the load balance equation converges. If it does not converge, adjust the eccentricity and then adjust the film thickness, and enter the next iterative calculation until convergence;

[0047] 108: After convergence, output the calculation results and enter the mixed lubrication calculation of the shaft and the bearing under the external load at the next moment.

[0048] The present invention can grasp the lubrication contact characteristics between the shaft and the bearing in real time, which has important guiding significance for the optimal design of the bearing lubrication characteristics.

[0049] The program of the present invention is independently developed, with accurate and efficient calculation, applicable to various external loads in the time domain of the journal, such as unbalanced forces and impact forces, etc., and has strong controllability and applicability.

[0050] The present invention can comprehensively consider the influence of factors such as different bearing specific pressures, rotational speeds, groove forms, and viscosities of lubricating media in the deep-sea high-pressure environment on the mixed lubrication characteristics of the bearing, and has strong scalability.

[0051] The present invention can directly identify the time-domain friction excitation force between the shaft and the bearing, and can identify the spectral characteristics of the friction excitation force through Fourier spectrum transformation, which can provide strong support for the low-noise optimal design of the bearing.

[0052] The above description is an explanation of the present invention, not a limitation of the invention. For the scope defined by the present invention, please refer to the claims. Within the protection scope of the present invention, any form of modification can be made.

Claims

1. A method for calculating the time domain mixed lubrication characteristics of sliding bearings under deep sea high pressure environment, characterized by: The following operation procedures are included: S1: Determine the parameters of input shaft and bearing geometry, lubrication medium, speed, hydrostatic pressure, and surface morphology; S2: Input the external load of the journal at the initial moment; S3: According to the water film thickness equation h(θ) = C + ecos(θ-ψ) + δ B (θ,z,p)+h j (θ,z), assuming the initial water film thickness, C is the initial clearance, e is the journal eccentricity, θ is the circumferential coordinate, ψ is the offset angle, δ B is the elastic deformation of the bearing shell, h j is the groove depth; S4: Iterative solution of the steady-state Reynolds average equation based on the finite difference method To obtain the water film pressure, R in the equation B is the bearing radius, φ θ and φ z is the pressure flow factor, φ s is the shear flow factor, U is the linear velocity of the axis, η is the viscosity of water, h T is the gap between the two surfaces, the gap between the two rough surfaces h T Relationship with nominal clearance h φ c is the contact factor; S5: Calculate the contact pressure between the shaft and the bearing surface based on the asperity contact model; S6: Reference the elastic deformation equation of Winkler bearing Calculate the elastic deformation of the bearing shell, p in the equation sum is the sum of deep sea hydrostatic pressure, water film pressure and asperity contact pressure, t is the thickness of rubber lining, E is the elastic modulus of bearing, ν is Poisson's ratio; S7: Determine whether the load balance equation converges; S8: After convergence, the calculation results are output and the mixed lubrication calculation of the shaft and bearing under the external load at the next moment is entered.

2. The method for calculating the time domain mixed lubrication characteristics of sliding bearings in a deep sea high pressure environment according to claim 1, characterized in that: Based on the steady-state Reynolds average equation of coupled interface roughness and taking into account the contact effect between the shaft and the bearing micro-convex body, the Winkler elastic deformation model is introduced to calculate the elastic deformation of the bearing under deep-sea high-pressure environment, which can effectively balance the calculation accuracy and solution time.

3. The method for calculating the time domain mixed lubrication characteristics of sliding bearings in a deep sea high pressure environment according to claim 1, characterized in that: By ensuring that the steady-state mixed lubrication contact force of the bearing is balanced with the external load at each moment, the calculation of the time-domain mixed lubrication characteristics of the shaft and bearing is realized.

4. The method for calculating the time domain mixed lubrication characteristics of a sliding bearing under a deep sea high pressure environment as claimed in claim 1, characterized in that: It can calculate the influence of different bearing pressure ratios, rotation speeds, groove forms, and viscosity parameters of the lubricating medium on the mixed lubrication characteristics of bearings under deep-sea high-pressure environments.

5. The method for calculating the time domain mixed lubrication characteristics of a sliding bearing under a deep sea high pressure environment as claimed in claim 1, characterized in that: The time domain friction excitation force between the shaft and the bearing can be identified, and the frequency spectrum characteristics of the friction excitation force can be identified through Fourier transform.

6. The method for calculating the time domain mixed lubrication characteristics of a sliding bearing in a deep sea high pressure environment according to claim 1, characterized in that: In S2, the time interval dt for solution calculation is defined to discretize the time domain external load on the journal.

7. The method for calculating the time domain mixed lubrication characteristics of a sliding bearing in a deep sea high pressure environment according to claim 1, characterized in that: In S7, if the load balance equation does not converge, the eccentricity is adjusted and then the film thickness is adjusted, and the next iterative calculation is entered until convergence.

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