A method and system for calculating a power characteristic coefficient of a sliding bearing

Abstract

The application belongs to the technical field of equipment evaluation, and discloses a kind of calculation method and system of sliding bearing dynamic characteristic coefficient, comprising: taking half of real oil film model as research object at axial symmetry plane, and setting the side surface of film and oil inlet located at axial symmetry as symmetry plane, which can significantly save computing resources and speed up the calculation speed;And the film and the oil inlet are separately divided into grids, and the outer wall surface of the film and the bottom surface of the oil inlet are set as grid interfaces, which can realize automatic grid division while ensuring grid quality;The application applies displacement, speed small disturbance to the journal in the equilibrium position by UDF in Fluent software, realizes the calculation of sliding bearing dynamic characteristic coefficient, and effectively improves the calculation accuracy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of equipment evaluation, and relates to a calculation method and system for dynamic characteristic coefficients of a sliding bearing. BACKGROUND

[0002] Dense-phase CO2 refers to a special state of CO2 under conditions of a critical pressure and a critical temperature, has the characteristics of high density and low viscosity, can significantly reduce transportation and storage costs, and is widely used in the field of CCUS (carbon capture, utilization and storage). The delivery pump is the core equipment of the dense-phase CO2 transportation link, which realizes the pressurization of the dense-phase CO2 through the rotation of the impeller. The sliding bearing is a key component of the dense-phase CO2 delivery pump, which bears the load through the dynamic pressure lubricating oil film formed between the shaft neck and the bearing bush, reduces the friction and wear, effectively absorbs the vibration impact, and further improves the operation stability of the delivery pump. The dynamic characteristic coefficients (including stiffness and damping coefficients) of the sliding bearing will significantly affect the rotor dynamics performance of the dense-phase CO2 delivery pump, and further affect the operation efficiency and service life of the whole machine. Accurate and convenient calculation of the dynamic characteristic coefficients of the sliding bearing under certain speed and load is the basis for studying the performance of the dense-phase CO2 delivery pump, and can provide a reference for the research and improvement of the dense-phase CO2 delivery pump. The existing technical solutions can be mainly divided into two kinds: one is to construct the corresponding control equation, and to perform numerical calculation by means of programming languages such as Matlab and Python to obtain the dynamic characteristic coefficients of the sliding bearing. This scheme has a high operation threshold and difficulty, requires the operator to have a certain mathematical and programming level, and needs to introduce many simplified assumptions (such as ignoring the pressure change in the thickness direction of the oil film and ignoring the axial heat transfer of the oil film), which affects the calculation accuracy. The other is to apply commercial CFD software such as Fluent to calculate the dynamic characteristic coefficients of the sliding bearing; first, this scheme adopts ICEM software to perform structured grid division on the bearing oil film model, which needs to be manually operated and is not conducive to automatic division; in addition, this scheme adopts the shaft neck oil film force monitoring macro and displacement macro iteration to determine the stable position of the shaft neck, which has low calculation efficiency; finally, this scheme assumes that the viscosity of the lubricating oil is a constant value, and ignores the influence of the temperature field on the viscosity of the lubricating oil, which cannot guarantee the calculation accuracy. SUMMARY

[0003] The purpose of the present application is to solve the problem that the existing technology cannot quickly and accurately obtain the dynamic characteristic coefficients of the sliding bearing under the speed and load to meet the research and improvement of the dense-phase CO2 delivery pump in the field of CCUS, and to provide a calculation method and system for the dynamic characteristic coefficients of the sliding bearing.

[0004] To achieve the above purpose, the following technical scheme is adopted in the present application:

[0005] A calculation method for dynamic characteristic coefficients of a sliding bearing comprises:

[0006] constructing an oil film model of the sliding bearing, and taking half of the real oil film model at an axial symmetry plane as a research object;

[0007] importing the oil film model into the DesignModeler module of Workbench, and setting the horizontal and vertical offset amounts of the journal as input parameters;

[0008] in the Mesh module of Workbench, defining the symmetry plane, inlet, outlet, wall surface and interface of the oil film model, and performing mesh division on the constructed half-block oil film model to obtain a bearing oil film grid file;

[0009] importing the bearing oil film grid file into the Fluent software, and setting the solution type for the bearing oil film grid file, the material properties of the lubricating oil and the lubricating oil vapor contained in the bearing oil film grid file in the Fluent, and then simulating the relationship between the lubricating oil and the lubricating oil vapor;

[0010] simulating the flow characteristics of the lubricating oil based on a viscosity model, setting the boundary conditions when simulating, setting the interface as a grid interface, and monitoring the mass flow difference of the input and output of the viscosity model, and judging whether the viscosity model simulation reaches a stable state based on the difference value of the mass flow difference;

[0011] if the stable state is reached, initializing the multiphase flow simulation in the Fluent software, obtaining the oil film pressure field based on the horizontal and vertical offset amounts of the journal;

[0012] in the CFD Post module of Workbench, obtaining the relationship between the oil film forces in the horizontal and vertical directions of the journal based on the oil film pressure field, and then obtaining the equilibrium position of the journal;

[0013] respectively applying a small displacement perturbation and an acceleration perturbation to the journal at the equilibrium position through UDF, and obtaining the stiffness coefficient and the damping coefficient of the bearing.

[0014] Further improvements of the application are as follows:

[0015] Further, the oil film model of the sliding bearing is constructed, specifically: based on the Solidworks software, an oil film model of the sliding bearing is established, half of the oil film model at an axial symmetry plane is taken as a research object, and the half oil film model includes a cylindrical film 1 and an oil inlet 2; the oil inlet 2 is arranged on the film 1.

[0016] Further, in the Mesh module of Workbench, the symmetry plane, inlet, outlet, wall surface and interface of the oil film model are defined, specifically: the side surface of the film 1 and the oil inlet 2 located at the axial symmetry is defined as the symmetry plane, the top surface of the oil inlet 2 is defined as the inlet, the other side surface of the film 1 is defined as the outlet, the inner wall surface of the film 1 is defined as the moving wall surface, the remaining surfaces are defined as the stationary wall surface, and the outer wall surface of the film 1 and the bottom surface of the oil inlet 2 are set as the interface.

[0017] Further, in Fluent, the solution type for the bearing oil film grid file, the material properties of the lubricating oil and the lubricating oil vapor contained in the bearing oil film grid file are set, and then the relationship between the lubricating oil and the lubricating oil vapor is simulated, specifically: selecting "Steady" steady state as the solution type; selecting N32 lubricating oil, and setting the lubricating oil viscosity through the UDF containing the viscosity-temperature effect; setting multiphase flow, selecting Mixture model, and setting the liquid phase material and the corresponding density, viscosity physical quantities; and the density, specific heat capacity physical quantities of the gas phase material, the mass transfer selects the Schnerr-Sauer model in Cavitation, and the vaporization pressure is set to 30000Pa; selecting Laminar model as the viscosity model, and selecting ViscousHeating to consider the viscous heating of the lubricating oil; setting the operating pressure to 0Pa.

[0018] Further, based on the viscosity model, the flow characteristics of the lubricating oil are simulated, and the boundary conditions during simulation are set, the interface is set as the grid interface, and the mass flow difference of the input and output of the viscosity model is monitored, based on the difference value of the mass flow difference, whether the viscosity model simulation reaches a stable state is judged, specifically:

[0019] The boundary conditions are the inlet gauge pressure and the inlet temperature, the outlet gauge pressure and the total backflow temperature, the rotating speed of the moving wall surface, the heat transfer coefficient and the temperature of the fluid flowing into the calculation area, at this time the wall surface thickness is set to 40mm, the heat transfer condition is selected as Convection, and the other wall surfaces are set as stationary wall surfaces, in the setting of the heat transfer condition, the wall surface thickness is set to 15mm, and the remaining settings are the same as those of the moving wall surface; the calculation area is the area composed of the inlet, the outlet, the moving wall surface and the other stationary wall surfaces;

[0020] Based on the multiphase flow problem, in the pressure-velocity coupling algorithm, Coupled is selected as the solution method, and the spatial discretization format is set, including: the pressure format is selected as PRESTO!, the other flux formats are selected as FirstOrderUpwind as the discretization format, the iteration number is set to 500 times, and the mass flow difference of the inlet and the outlet is monitored, when the difference value is less than 1%, it is considered that the iteration converges.

[0021] Further, the initialization of the multiphase flow simulation in the Fluent software is carried out, and based on the horizontal and vertical offsets of the shaft neck, the oil film pressure field is obtained, specifically:

[0022] The mixed initialization is selected, based on the set simulation boundary conditions and the defined fluid properties, the steady-state solver is configured, the horizontal and vertical offsets of the shaft neck are taken as P1 and P2 respectively as the initial conditions of the simulation, the simulation is started and waits for its convergence, and the oil film pressure field is obtained;

[0023] The horizontal oil film force acting on the shaft neck is set as F x = force_x()@moving_wall×2, the vertical oil film force is set as F y = force_y()@moving_wall×2, the ratio of the two is set as λ = F x / F y , and F y and λ are set as output quantities, which are P3 and P4 respectively, wherein force_x() represents the x-axis component force; force_y() represents the y-axis component force; @moving_wall represents the force acting on the wall moving_wall.

[0024] Further, in the CFDPost module of Workbench, based on the oil film pressure field, the relationship between the horizontal and vertical oil film forces of the shaft neck is obtained, and then the balance position of the shaft neck is obtained, specifically: the values of P1 and P2 are changed to obtain P3 and P4 corresponding to a series of design points composed of P1 and P2, and a response surface is generated, the optimization target is set as P3 = 5000N, P4 = 0, the tolerance is 0.001, and the candidate design point closest to the optimization target is calculated and selected, which is the balance position of the shaft neck.

[0025] Further, small perturbations of displacement and acceleration are respectively applied to the shaft neck at the balance position through UDF, and the stiffness coefficient and damping coefficient of the bearing are obtained, specifically:

[0026] The stiffness coefficient of the bearing is calculated by applying small perturbations of displacement to the shaft neck at the balance position, taking the displacement perturbations ±Δx and ±Δy, and the corresponding relationship between each perturbation and the calculated oil film force is:

[0027]

[0028] The stiffness coefficient of the bearing is represented as:

[0029]

[0030] The damping coefficients of the bearing are calculated by applying a small disturbance of velocity to the journal at the equilibrium position through UDF, and the corresponding relationship between each disturbance and the calculated oil film force is:

[0031]

[0032] The bearing damping coefficients are expressed as:

[0033]

[0034] Where, F x1 represents the change of the x-direction oil film force under the action of the displacement disturbance +Δx; F y1 represents the change of the y-direction oil film force under the action of the displacement disturbance +Δx;

[0035] F x2 represents the change of the x-direction oil film force under the action of the displacement disturbance -Δx; F y2 represents the change of the y-direction oil film force under the action of the displacement disturbance -Δx;

[0036] F x3 represents the change of the x-direction oil film force under the action of the displacement disturbance +Δy; F y3 represents the change of the y-direction oil film force under the action of the displacement disturbance +Δy;

[0037] F x4 represents the change of the x-direction oil film force under the action of the displacement disturbance -Δy; F y4 represents the change of the y-direction oil film force under the action of the displacement disturbance -Δy;

[0038] k xx represents the force required to be applied in the x-direction when the journal produces a unit displacement in the x-direction;

[0039] k xy represents the force required to be applied in the x-direction when the journal produces a unit displacement in the y-direction;

[0040] k yx represents the force required to be applied in the y-direction when the journal produces a unit displacement in the x-direction;

[0041] k yy represents the force required to be applied in the y-direction when the journal produces a unit displacement in the y-direction;

[0042] F x5 represents the change of the x-direction oil film force under the action of the velocity disturbance +Δx'; F y5 represents the change of the y-direction oil film force under the action of the velocity disturbance +Δx';

[0043] Fx6 represents the change of the x-direction oil film force under the action of the speed disturbance -Δx'; F y6 represents the change of the y-direction oil film force under the action of the speed disturbance -Δx';

[0044] F x7 represents the change of the x-direction oil film force under the action of the speed disturbance +Δy'; F y7 represents the change of the y-direction oil film force under the action of the speed disturbance +Δy';

[0045] F x8 represents the change of the x-direction oil film force under the action of the speed disturbance -Δy'; F y8 represents the change of the y-direction oil film force under the action of the speed disturbance -Δy';

[0046] d xx represents the force required to be applied in the x-direction when the journal generates a unit speed in the x-direction;

[0047] d xy represents the force required to be applied in the x-direction when the journal generates a unit speed in the y-direction;

[0048] d yx represents the force required to be applied in the y-direction when the journal generates a unit speed in the x-direction;

[0049] d yy represents the force required to be applied in the y-direction when the journal generates a unit speed in the y-direction.

[0050] A system for calculating the dynamic characteristic coefficient of a sliding bearing, comprising:

[0051] a construction module, which constructs an oil film model of the sliding bearing and takes half of the real oil film model at an axial symmetry plane as a research object;

[0052] a parameter setting module, which imports the oil film model into a DesignModeler module of Workbench and sets the horizontal and vertical offset amounts of the journal as input parameters;

[0053] a mesh division module, which defines the symmetry plane, inlet, outlet, wall surface and interface of the oil film model in a Mesh module of Workbench, performs mesh division on the constructed half-block oil film model, and obtains a bearing oil film mesh file;

[0054] The attribute definition module imports the bearing oil film grid file into the Fluent software, sets the solving type for the bearing oil film grid file, and sets the material attributes of the lubricating oil and the lubricating oil vapor contained in the bearing oil film grid file in the Fluent, and then simulates the relationship between the lubricating oil and the lubricating oil vapor.

[0055] The judging module simulates the flow characteristics of the lubricating oil based on the viscosity model, sets the boundary condition when the simulation is performed, sets the interface as the grid interface, and monitors the mass flow difference of the input and output of the viscosity model, judges whether the viscosity model simulation reaches a stable state based on the difference value of the mass flow difference.

[0056] The initialization module initializes the multiphase flow simulation in the Fluent software if the stable state is reached, and obtains the oil film pressure field based on the horizontal and vertical offset amounts of the journal.

[0057] The first obtaining module obtains the relationship between the oil film forces in the horizontal and vertical directions of the journal in the CFD Post module of the Workbench based on the oil film pressure field, and then obtains the balance position of the journal.

[0058] The second obtaining module respectively applies a small displacement disturbance and an acceleration small disturbance to the journal at the balance position through the UDF, and obtains the stiffness coefficient and the damping coefficient of the bearing.

[0059] Compared with the prior art, the present application has the following beneficial effects:

[0060] The present application takes half of the real oil film model at the axial symmetry plane as the research object, and sets the side surface where the film and the oil inlet are located at the axial symmetry as the symmetry plane, which can significantly save the calculation resources and speed up the calculation speed; the outer wall surface of the film and the bottom surface of the oil inlet are set as the grid interface, which can realize the automatic grid division while ensuring the grid quality; the present application applies the displacement and the speed small disturbance to the journal at the balance position through the UDF in the Fluent software, realizes the calculation of the dynamic characteristic coefficients of the sliding bearing, and effectively improves the calculation accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0061] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0062] Figure 1A flowchart of the calculation method of the sliding bearing dynamic characteristic coefficient of the present application;

[0063] Figure 2 A structural diagram of the calculation system of the sliding bearing dynamic characteristic coefficient of the present application;

[0064] Figure 3 A flowchart of the calculation method of the sliding bearing dynamic characteristic coefficient of the present application;

[0065] Figure 4 A schematic diagram of a half oil film model;

[0066] Figure 5 A schematic diagram of grid division of an oil film model. DETAILED DESCRIPTION

[0067] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0068] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0069] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0070] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0071] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. As "horizontal" only means that its direction is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0072] In the description of the embodiments of the application, it should also be noted that, unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0073] The application will be described in further detail below with reference to the drawings:

[0074] Referring to Figure 1 The application discloses a calculation method of a sliding bearing dynamic characteristic coefficient, comprising:

[0075] S101, constructing an oil film model of the sliding bearing, and taking half of the real oil film model at an axial symmetry plane as a research object;

[0076] The oil film model of the sliding bearing is constructed, specifically: based on the Solidworks software, an oil film model of the sliding bearing is established, and half of the oil film model at an axial symmetry plane is taken as a research object. The half oil film model comprises a cylindrical film 1 and an oil inlet 2; the oil inlet 2 is arranged on the film 1.

[0077] S102, importing the oil film model into the DesignModeler module of Workbench, and setting the horizontal offset and vertical offset of the journal as input parameters;

[0078] S103, in the Mesh module of Workbench, defining the symmetry plane, inlet, outlet, wall surface and interface of the oil film model, and performing mesh division on the constructed half oil film model to obtain a bearing oil film grid file;

[0079] The side surface of the film 1 and the oil inlet 2 at the axial symmetry is defined as the symmetry plane, the top surface of the oil inlet 2 is defined as the inlet, the other side surface of the film 1 is defined as the outlet, the inner wall surface of the film 1 is defined as the moving wall surface, the remaining surfaces are defined as the static wall surface, and the outer wall surface of the film 1 and the bottom surface of the oil inlet 2 are set as the interface

[0080] S104, import the bearing oil film grid file into the Fluent software, and set the solution type for the bearing oil film grid file, the material properties of the lubricating oil and the lubricating oil vapor contained in the bearing oil film grid file in the Fluent, and then simulate the relationship between the lubricating oil and the lubricating oil vapor;

[0081] Select "Steady" steady state as the solution type; select N32 lubricating oil, and set the viscosity of the lubricating oil through the UDF containing the viscosity-temperature effect; set the multiphase flow, select the Mixture model, and set the density, viscosity physical quantities of the liquid phase material and the corresponding density, specific heat capacity physical quantities of the gas phase material; the mass transfer selects the Schnerr-Sauer model in Cavitation, and the vaporization pressure is set to 30000Pa; select Laminar model as the viscosity model, and select ViscousHeating to consider the viscous heating of the lubricating oil; set the operating pressure to 0Pa.

[0082] S105, simulate the flow characteristics of the lubricating oil based on the viscosity model, and set the boundary conditions when simulating, set the interface as the grid interface, and monitor the mass flow difference of the input and output of the viscosity model, based on the difference value of the mass flow difference, judge whether the viscosity model simulation reaches a steady state or not;

[0083] The boundary conditions are the inlet gauge pressure and the inlet temperature, the outlet gauge pressure and the total backflow temperature, the rotating speed of the moving wall, the heat transfer coefficient, and the temperature of the fluid when flowing into the calculation area, at this time, the wall thickness is set to 40mm, the heat transfer condition is selected as Convection, and the other walls are set as stationary walls, in the setting of the heat transfer condition, the wall thickness is set to 15mm, and the rest is the same as the moving wall; the calculation area is the area composed of the inlet, the outlet, the moving wall and the other stationary walls;

[0084] Based on the multiphase flow problem, select Coupled as the solution method in the pressure-velocity coupling algorithm, and set the spatial discretization format, including: the pressure format selects PRESTO!, all other flux formats select First OrderUpwind as the discretization format, the iteration number is set to 500 times, and the mass flow difference of the inlet and the outlet is monitored, when the difference value is less than 1%, it is considered that the iteration converges.

[0085] S106, if a steady state is reached, initialize the multiphase flow simulation in the Fluent software, and obtain the oil film pressure field based on the horizontal and vertical offset of the shaft journal;

[0086] Selecting mixed initialization, configuring the steady-state solver based on the set simulation boundary conditions and defined fluid properties, taking the horizontal and vertical displacement of the shaft journal as P1 and P2 respectively as the initial conditions of the simulation; starting the simulation and waiting for its convergence, obtaining the oil film pressure field;

[0087] Setting the horizontal oil film force acting on the shaft journal as F x = force_x()@moving_wall x 2, and the vertical oil film force as F y = force_y()@moving_wall x 2, and setting the ratio of the two as λ = F x / F y , and setting F y and λ as the output quantities, P3 and P4 respectively.

[0088] S107, in the CFD Post module of Workbench, based on the oil film pressure field, obtaining the relationship between the horizontal and vertical oil film forces of the shaft journal, and further obtaining the equilibrium position of the shaft journal;

[0089] Changing the values of P1 and P2 to obtain P3 and P4 corresponding to a series of design points composed of P1 and P2, and generating a response surface, setting the optimization target as P3 = 5000 N, P4 = 0, and the tolerance as 0.001, calculating and selecting one candidate design point closest to the optimization target, which is the equilibrium position of the shaft journal.

[0090] S108, respectively applying a small displacement perturbation and a small acceleration perturbation to the shaft journal at the equilibrium position through UDF, obtaining the stiffness coefficient and the damping coefficient of the bearing.

[0091] Applying a small displacement perturbation to the shaft journal at the equilibrium position through UDF, calculating the stiffness coefficient of the bearing, taking displacement perturbations ±Δx and ±Δy, and the corresponding relationship between each perturbation and the calculated oil film force is:

[0092]

[0093] The bearing stiffness coefficient is represented as:

[0094]

[0095] Applying a small acceleration perturbation to the shaft journal at the equilibrium position through UDF, calculating the damping coefficient of the bearing, taking dimensionless speed perturbations ±Δx' and ±Δy', and the corresponding relationship between each perturbation and the calculated oil film force is:

[0096]

[0097] The bearing damping coefficient is represented as:

[0098]

[0099] where F x1 represents the change in the x-direction oil film force under the action of the displacement disturbance + Δx; F y1 represents the change in the y-direction oil film force under the action of the displacement disturbance + Δx;

[0100] F x2 represents the change in the x-direction oil film force under the action of the displacement disturbance - Δx; F y2 represents the change in the y-direction oil film force under the action of the displacement disturbance - Δx;

[0101] F x3 represents the change in the x-direction oil film force under the action of the displacement disturbance + Δy; F y3 represents the change in the y-direction oil film force under the action of the displacement disturbance + Δy;

[0102] F x4 represents the change in the x-direction oil film force under the action of the displacement disturbance - Δy; F y4 represents the change in the y-direction oil film force under the action of the displacement disturbance - Δy;

[0103] k xx represents the force required to be applied in the x-direction when a unit displacement is produced in the x-direction of the journal;

[0104] k xy represents the force required to be applied in the x-direction when a unit displacement is produced in the y-direction of the journal;

[0105] k yx represents the force required to be applied in the y-direction when a unit displacement is produced in the x-direction of the journal;

[0106] k yy represents the force required to be applied in the y-direction when a unit displacement is produced in the y-direction of the journal;

[0107] F x5 represents the change in the x-direction oil film force under the action of the velocity disturbance + Δx'; F y5 represents the change in the y-direction oil film force under the action of the velocity disturbance + Δx';

[0108] F x6 represents the change in the x-direction oil film force under the action of the velocity disturbance - Δx'; F y6 represents the change in the y-direction oil film force under the action of the velocity disturbance - Δx';

[0109] F x7 represents the change in the x-direction oil film force under the action of the velocity disturbance + Δy'; F y7Fy' represents the change of the y-direction oil film force under the action of the speed disturbance + Δy';

[0110] F x8 Fx' represents the change of the x-direction oil film force under the action of the speed disturbance - Δy'; y8 Fy' represents the change of the y-direction oil film force under the action of the speed disturbance - Δy';

[0111] d xx Fx represents the force required to be applied in the x-direction when the journal generates a unit speed in the x-direction;

[0112] d xy Fx represents the force required to be applied in the x-direction when the journal generates a unit speed in the y-direction;

[0113] d yx Fy represents the force required to be applied in the y-direction when the journal generates a unit speed in the x-direction;

[0114] d yy Fy represents the force required to be applied in the y-direction when the journal generates a unit speed in the y-direction.

[0115] Referring to Figure 2 The application discloses a kind of calculation system of sliding bearing dynamic characteristic coefficient, comprising:

[0116] The construction module constructs the oil film model of sliding bearing, and takes the half of real oil film model at axial symmetry plane as research object;

[0117] The parameter setting module imports oil film model into the DesignModeler module of Workbench, and sets the horizontal offset and vertical offset of journal as input parameters;

[0118] The grid division module defines the symmetry plane, inlet, outlet, wall surface and interface of oil film model in the Mesh module of Workbench, and carries out grid division to the constructed half-block oil film model, obtains bearing oil film grid file;

[0119] The attribute definition module imports bearing oil film grid file into Fluent software, and sets the solution type of bearing oil film grid file, the material properties of lubricating oil and lubricating oil vapor contained in bearing oil film grid file in Fluent, to simulate the relationship between lubricating oil and lubricating oil vapor;

[0120] The judgment module simulates the flow characteristics of lubricating oil based on a viscous model, sets the boundary conditions for the simulation, sets the interface as a mesh interface, monitors the mass flow difference between the input and output of the viscous model, and judges whether the viscous model simulation has reached a stable state based on the magnitude of the mass flow difference.

[0121] An initialization module, if it reaches a stable state, initializes the multiphase flow simulation in Fluent software and obtains the oil film pressure field based on the journal's horizontal and vertical offsets.

[0122] The first acquisition module, located in the CFD Post module of Workbench, acquires the relationship between the oil film forces in the horizontal and vertical directions of the journal based on the oil film pressure field, and then acquires the equilibrium position of the journal.

[0123] The second acquisition module applies small displacement and small acceleration disturbances to the journal at the equilibrium position via UDF to acquire the stiffness coefficient and damping coefficient of the bearing.

[0124] Example:

[0125] See Figure 3 This invention discloses a method for calculating the dynamic characteristic coefficient of a sliding bearing, comprising:

[0126] Step 1: Use Solidworks software to create an oil film model of the sliding bearing, preferably such as... Figure 4 As shown, in order to save computing resources and speed up the calculation, half of the real oil film model is taken as the research object at the axial symmetry plane. The half oil film model includes two parts, namely a cylindrical film 1 between the journal and the bearing and a semi-cylindrical oil inlet 2. The inner diameter of the film 1 is 79.8 mm, the outer diameter is 80 mm, and the width is 50 mm. The diameter of the oil inlet 2 is 4 mm and the height is 5 mm.

[0127] Step 2: Import the oil film model into the DesignModeler module of Workbench, set the journal horizontal offset and vertical offset from Step 1 as input parameters, namely P1 and P2, and set initial values ​​to prepare for response surface optimization. Preferably, the initial value of P1 is set to 0.02mm and P2 is set to 0.03mm.

[0128] Step three: select and define the symmetry plane, inlet, outlet, wall and interface of the oil film model in the Mesh module, preferably, define the side of the film 1 and the oil inlet 2 located at the axial symmetry as the symmetry plane, define the top surface of the oil inlet 2 as the inlet, define the other side of the film 1 as the outlet, define the inner wall surface of the film 1 as the moving wall surface, define the remaining surfaces as the static wall surface, and define the outer wall surface of the film 1 and the bottom surface of the oil inlet 2 as the interface;

[0129] Step four: automatically divide the mesh of the half oil film model, preferably, as shown in Figure 5 , divide the film 1 into 720 equal parts in the circumferential direction, 150 equal parts in the axial direction, and 5 equal parts in the thickness direction, divide the oil inlet 2 into 12 equal parts in the circumferential direction and the radial direction, and 16 equal parts in the height direction;

[0130] Step five: select steady-state solution in Fluent;

[0131] Step six: set the material properties of the lubricating oil and the lubricating oil vapor in Fluent, preferably, select N32 lubricating oil, set the viscosity of the lubricating oil through the UDF containing the viscosity-temperature effect, and set the gas phase material for the lubricating oil vapor;

[0132] Step seven: open the multiphase flow in Fluent, preferably, select the Mixture model, select the liquid phase material for the first phase, select the gas phase material for the second phase, select the Schnerr-Sauer model in Cavitation for mass transfer, and set the vaporization pressure to 30000 Pa;

[0133] Step eight: set the viscosity model in Fluent, preferably, select the Laminar model, and check Viscous Heating to introduce the viscous heating of the lubricating oil;

[0134] Step nine: set the operating pressure in Fluent, preferably, set the operating pressure to 0 Pa;

[0135] Step ten: set the boundary conditions in Fluent, preferably, set the inlet gage pressure to 120000 Pa, the temperature to 298.15 K, the outlet gage pressure to 101325 Pa, the backflow total temperature to 298.15 K, the rotating speed of the moving wall surface to 2000 rpm, the thermal condition to Convection, the heat transfer coefficient to 50 W / (m 2 ·K), the incoming flow temperature to 298.15 K, and the wall thickness to 40 mm, set the remaining walls as static walls, and set the wall thickness to 15 mm in the thermal condition setting, and the remaining settings are the same as those of the moving wall surface;

[0136] Step eleven: set the grid interface in Fluent, preferably, set the interface defined in step three as the grid interface;

[0137] Step twelve: set the solution method in Fluent, preferably, the pressure-velocity coupling algorithm is selected as Coupled format, in spatial discretization, the pressure format is selected as PRESTO!, other flux formats are all selected as first order upwind, the iteration number is set as 500 times, the mass flow difference of the inlet and outlet is monitored, when the difference is less than 1%, it is considered as iteration convergence;

[0138] Step thirteen: initialize in Fluent, preferably, mixed initialization is selected;

[0139] Step fourteen: perform the first calculation in Fluent, to obtain the oil film pressure field when P1 and P2 are initial values;

[0140] Step fifteen: set the output quantity in CFD Post module, preferably,

[0141] The horizontal direction oil film force acting on the journal is set as F x = force_x()@moving_wall×2, the vertical direction oil film force is set as F y = force_y()@moving_wall×2, the ratio of the two is set as λ = F x / F y , and F y and λ are set as output quantities, which are P3 and P4 respectively;

[0142] Step sixteen: solve the equilibrium position of the journal by using the response surface optimization module, preferably, a series of design points composed of P1 and P2 are calculated to obtain P3 and P4, and a response surface is generated, the optimization target is set as P3 = 5000N, P4 = 0, the tolerance is 0.001, and the candidate design point closest to the optimization target is calculated and selected, that is, P1 = 0.036155mm, P2 = 0.032725mm, which is the equilibrium position of the journal, at this time F x0 = -4.33N, F y0 = 4991.71N;

[0143] Step seventeen: apply a small displacement perturbation to the journal at the equilibrium position through UDF, to calculate the stiffness coefficient of the bearing, the displacement perturbation is ±Δx and ±Δy, and the corresponding relationship between each perturbation and the calculated oil film force is:

[0144]

[0145] The bearing stiffness coefficient can be expressed as:

[0146]

[0147] Preferably, the displacement perturbation Δx = 1 x 10 -3 mm, Δy = 1 x 10 -3 mm, and the following results are obtained:

[0148]

[0149] Step eight: the small velocity perturbation is applied to the journal at the equilibrium position by UDF, the damping coefficient of the bearing is calculated, the dimensionless velocity perturbation ± Δx' and ± Δy' are taken, and the corresponding relationship between each perturbation and the calculated oil film force is as follows:

[0150]

[0151] The bearing damping coefficient can be expressed as:

[0152]

[0153] Preferably, the transient solution is selected in Fluent, the time step is set to 1 x 10 -5 s, the number of steps is 10, the maximum number of iterations for each step is 100, the grid is activated, and the remaining settings are kept unchanged, the velocity perturbation Δx' = 0.262 mm / s and Δy' = 0.262 mm / s are taken, and the following results are obtained:

[0154]

[0155] Wherein, F x1 represents the change amount of the x-direction oil film force under the action of the displacement perturbation + Δx; F y1 represents the change amount of the y-direction oil film force under the action of the displacement perturbation + Δx;

[0156] F x2 represents the change amount of the x-direction oil film force under the action of the displacement perturbation - Δx; F y2 represents the change amount of the y-direction oil film force under the action of the displacement perturbation - Δx;

[0157] F x3 represents the change amount of the x-direction oil film force under the action of the displacement perturbation + Δy; F y3 represents the change amount of the y-direction oil film force under the action of the displacement perturbation + Δy;

[0158] F x4 represents the change amount of the x-direction oil film force under the action of the displacement perturbation - Δy; F y4 represents the change amount of the y-direction oil film force under the action of the displacement perturbation - Δy;

[0159] k xxFkx represents the force required to be applied in the x direction when the journal produces a unit displacement in the x direction;

[0160] k xy Fky represents the force required to be applied in the x direction when the journal produces a unit displacement in the y direction;

[0161] k yx Fkx represents the force required to be applied in the y direction when the journal produces a unit displacement in the x direction;

[0162] k yy Fky represents the force required to be applied in the y direction when the journal produces a unit displacement in the y direction;

[0163] F x5 Fkx represents the change in the x direction oil film force under the action of the speed disturbance + Δx'; y5 Fky represents the change in the y direction oil film force under the action of the speed disturbance + Δx';

[0164] F x6 Fkx represents the change in the x direction oil film force under the action of the speed disturbance - Δx'; y6 Fky represents the change in the y direction oil film force under the action of the speed disturbance - Δx';

[0165] F x7 Fkx represents the change in the x direction oil film force under the action of the speed disturbance + Δy'; y7 Fky represents the change in the y direction oil film force under the action of the speed disturbance + Δy';

[0166] F x8 Fkx represents the change in the x direction oil film force under the action of the speed disturbance - Δy'; y8 Fky represents the change in the y direction oil film force under the action of the speed disturbance - Δy';

[0167] d xx Fkx represents the force required to be applied in the x direction when the journal produces a unit velocity in the x direction;

[0168] d xy Fkx represents the force required to be applied in the x direction when the journal produces a unit velocity in the y direction;

[0169] d yx Fkx represents the force required to be applied in the y direction when the journal produces a unit velocity in the x direction;

[0170] d yy Fkx represents the force required to be applied in the y direction when the journal produces a unit velocity in the y direction.

[0171] The above merely describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calculating the dynamic characteristic coefficient of a sliding bearing, characterized in that, include: An oil film model of a sliding bearing is constructed, and half of the real oil film model is taken at the axial symmetry plane as the research object. Import the oil film model into the DesignModeler module of Workbench, and set the journal horizontal offset and vertical offset as input parameters; In the Mesh module of Workbench, define the symmetry plane, inlet, outlet, wall and interface of the oil film model, and mesh the constructed half-block oil film model to obtain the bearing oil film mesh file. Import the bearing oil film mesh file into Fluent software, and set the solution type for the bearing oil film mesh file and the material properties of the lubricating oil and lubricating oil vapor contained in the bearing oil film mesh file in Fluent, so as to simulate the relationship between the lubricating oil and lubricating oil vapor. The flow characteristics of lubricating oil are simulated based on a viscous model. Boundary conditions are set for the simulation, the interface is set as a mesh interface, and the mass flow rate difference between the input and output of the viscous model is monitored. Based on the magnitude of the mass flow rate difference, it is determined whether the viscous model simulation has reached a steady state. If a steady state is reached, the multiphase flow simulation in Fluent software is initialized, and the oil film pressure field is obtained based on the horizontal and vertical offsets of the journal. In the CFD Post module of Workbench, the relationship between the oil film forces in the horizontal and vertical directions of the journal is obtained based on the oil film pressure field, and then the equilibrium position of the journal is obtained. By applying small displacement and small acceleration disturbances to the journal at the equilibrium position using UDF, the stiffness coefficient and damping coefficient of the bearing are obtained. The method involves applying small displacement and small acceleration disturbances to the journal at the equilibrium position using a UDF to obtain the bearing's stiffness coefficient and damping coefficient, specifically: By applying a small displacement disturbance to the journal at the equilibrium position using UDF, the stiffness coefficient of the bearing is calculated, and the displacement disturbance is taken as... and The correspondence between each disturbance and the calculated oil film force is as follows: The bearing stiffness coefficient is expressed as: By applying a small velocity disturbance to the journal at the equilibrium position using UDF, the damping coefficient of the bearing is calculated, and a dimensionless velocity disturbance is taken. and The correspondence between each disturbance and the calculated oil film force is as follows: The bearing damping coefficient is expressed as: in, Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates journal at When direction produces unit velocity, in The force required to be applied in the direction; Indicates journal at When direction produces unit velocity, in The force required to be applied in the direction; Indicates journal at When direction produces unit velocity, in The force required to be applied in the direction; Indicates journal at When direction produces unit velocity, in The force required to direct the direction.

2. The method for calculating the dynamic characteristic coefficient of a sliding bearing according to claim 1, characterized in that, The construction of the oil film model of the sliding bearing is specifically as follows: the oil film model of the sliding bearing is established based on Solidworks software, and half of the oil film model is taken as the research object at the axial symmetry plane. The half oil film model includes a cylindrical film (1) and an oil inlet (2); the oil inlet (2) is set on the film (1).

3. The method for calculating the dynamic characteristic coefficient of a sliding bearing according to claim 2, characterized in that, In the Mesh module of Workbench, the symmetry plane, inlet, outlet, wall and interface of the oil film model are defined as follows: the side of the film (1) and the oil inlet (2) located at the axial symmetry point is defined as the symmetry plane, the top surface of the oil inlet (2) is defined as the inlet, the other side of the film (1) is defined as the outlet, the inner wall of the film (1) is defined as the moving wall, the remaining surfaces are defined as the stationary wall, and the outer wall of the film (1) and the bottom surface of the oil inlet (2) are set as the interface.

4. The method for calculating the dynamic characteristic coefficient of a sliding bearing according to claim 3, characterized in that, The process of setting the solution type for the bearing oil film mesh file and the material properties of the lubricating oil and lubricating oil vapor contained in the bearing oil film mesh file in Fluent to simulate the relationship between the lubricating oil and lubricating oil vapor is as follows: Select "Steady" steady state as the solution type; select N32 lubricating oil and set the lubricating oil viscosity through a UDF that includes the viscosity-temperature effect; set up multiphase flow, select the Mixture model, and set the liquid phase material and its corresponding density and viscosity physical properties; as well as the density and specific heat capacity physical properties of the gas phase material, select the Schnerr-Sauer model in Cavitation for mass transfer, and set the vaporization pressure to 30000 Pa; select the Laminar model as the viscosity model and select Viscous Heating to consider the viscous heating of the lubricating oil; set the operating pressure to 0 Pa.

5. The method for calculating the dynamic characteristic coefficient of a sliding bearing according to claim 4, characterized in that, The process involves simulating the flow characteristics of lubricating oil using a viscous model, setting boundary conditions for the simulation, defining the interface as a mesh interface, and monitoring the mass flow rate difference between the input and output of the viscous model. Based on the magnitude of this mass flow rate difference, the simulation is determined to have reached a steady state. Specifically: The boundary conditions are the inlet gauge pressure and temperature, the outlet gauge pressure and total return temperature, the rotational speed of the moving wall, the heat transfer coefficient, and the temperature of the fluid flowing into the computational domain. The wall thickness is set to 40 mm, the thermal condition is Convection, and other walls are set as stationary walls. In the thermal condition settings, the wall thickness is set to 15 mm, and the remaining settings are the same as for the moving wall. The computational domain is the area composed of the inlet, outlet, moving wall, and other stationary walls. Based on the multiphase flow problem, the Coupled algorithm is selected as the solution method in the pressure-velocity coupling algorithm. At the same time, the spatial discretization scheme is set, including: PRESTO for pressure scheme and First Order Upwind for other flux schemes. The number of iterations is set to 500. The mass flow rate difference between the inlet and outlet is monitored. When the difference between the two is less than 1%, it is considered that the iteration has converged.

6. The method for calculating the dynamic characteristic coefficient of a sliding bearing according to claim 5, characterized in that, The initialization of the multiphase flow simulation in Fluent software, based on the horizontal and vertical offsets of the journal, involves obtaining the oil film pressure field, specifically as follows: Select hybrid initialization, configure the steady-state solver based on the set simulation boundary conditions and defined fluid properties, and use the journal horizontal offset and vertical offset as P1 and P2 respectively as the initial conditions for the simulation; start the simulation and wait for it to converge to obtain the oil film pressure field; The horizontal oil film force acting on the journal is set to... The vertical oil film force is set to The ratio of the two is set to and will and Set as output values, respectively and In this context, force_x() represents the force component along the x-axis; force_y() represents the force component along the y-axis; and @moving_wall indicates that the force acts on the wall moving_wall.

7. The method for calculating the dynamic characteristic coefficient of a sliding bearing according to claim 6, characterized in that, In the CFD Post module of Workbench, based on the oil film pressure field, the relationship between the oil film forces in the horizontal and vertical directions of the journal is obtained, thereby obtaining the equilibrium position of the journal. Specifically: Change and The value of is obtained from and The series of design points constituted and And generate a response surface, and set the optimization objective as , With a tolerance of 0.001, the candidate design point that is closest to the optimization objective is calculated and selected, which is the balance position of the journal.

8. A system for calculating the dynamic characteristic coefficient of a sliding bearing, characterized in that, include: The construction module constructs an oil film model of a sliding bearing, and takes half of the real oil film model at the axial symmetry plane as the research object. The parameter setting module imports the oil film model into the DesignModeler module of Workbench and sets the journal horizontal offset and vertical offset as input parameters. The mesh generation module, located in the Mesh module of Workbench, defines the symmetry plane, inlet, outlet, wall, and interface of the oil film model, and performs mesh generation on the constructed half-block oil film model to obtain the bearing oil film mesh file. The attribute definition module imports the bearing oil film mesh file into Fluent software and sets the solution type for the bearing oil film mesh file, as well as the material properties of the lubricating oil and lubricating oil vapor contained in the bearing oil film mesh file, in Fluent to simulate the relationship between the lubricating oil and lubricating oil vapor. The judgment module simulates the flow characteristics of lubricating oil based on a viscous model, sets the boundary conditions for the simulation, sets the interface as a mesh interface, monitors the mass flow difference between the input and output of the viscous model, and judges whether the viscous model simulation has reached a stable state based on the magnitude of the mass flow difference. An initialization module, if it reaches a stable state, initializes the multiphase flow simulation in Fluent software and obtains the oil film pressure field based on the journal's horizontal and vertical offsets. The first acquisition module, located in the CFD Post module of Workbench, acquires the relationship between the oil film forces in the horizontal and vertical directions of the journal based on the oil film pressure field, and then acquires the equilibrium position of the journal. The second acquisition module applies small displacement disturbances and small acceleration disturbances to the journal at the equilibrium position via UDF to acquire the stiffness coefficient and damping coefficient of the bearing. The method involves applying small displacement and small acceleration disturbances to the journal at the equilibrium position using a UDF to obtain the bearing's stiffness coefficient and damping coefficient, specifically: By applying a small displacement disturbance to the journal at the equilibrium position using UDF, the stiffness coefficient of the bearing is calculated, and the displacement disturbance is taken as... and The correspondence between each disturbance and the calculated oil film force is as follows: The bearing stiffness coefficient is expressed as: By applying a small velocity disturbance to the journal at the equilibrium position using UDF, the damping coefficient of the bearing is calculated, and a dimensionless velocity disturbance is taken. and The correspondence between each disturbance and the calculated oil film force is as follows: The bearing damping coefficient is expressed as: in, Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates displacement disturbance Under the action Change in directional oil film force; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates journal at When a unit displacement is generated in the direction, in The force required to be applied in the direction; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates the velocity disturbance Under the action Change in directional oil film force; Indicates journal at When direction produces unit velocity, in The force required to be applied in the direction; Indicates journal at When direction produces unit velocity, in The force required to be applied in the direction; Indicates journal at When direction produces unit velocity, in The force required to be applied in the direction; Indicates journal at When direction produces unit velocity, in The force required to direct the direction.

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