Method for solving journal balance position of radial sliding bearing of dense-phase CO2 delivery pump

Abstract

The invention provides a method for solving a journal balance position of a radial sliding bearing of a dense-phase CO2 delivery pump, and the method comprises the steps: constructing an oil film model of the radial sliding bearing to be researched, and determining input parameters according to the oil film model; selecting and defining an inlet, a wall surface and an outlet of the oil film model so as to perform grid division on the oil film model; steady-state solution is selected in fluid simulation software, and material attributes, multiphase flow, a viscosity model, operation pressure, boundary conditions, a grid interface and a solution method are sequentially set; sequentially carrying out initialization and first calculation to obtain oil film pressure distribution when the journal is at the initial position; setting output parameters; a series of design points are generated in the response surface optimization experiment design module, and corresponding experiments are carried out; and generating a response surface based on an experimental result, and performing optimization according to the response surface to obtain the balance position of the journal. The method comprehensively considers the influence of factors such as viscous heating, viscosity-temperature effect and multiphase flow, is more consistent with the actual situation, and is high in calculation precision.

Description

Technical Field

[0001] The invention relates to the technical field of booster pumps and fluid dynamic pressure lubrication, and in particular to a method for solving the equilibrium position of a journal of a radial sliding bearing of a dense phase CO2 delivery pump. Background Art

[0002] Dense phase CO2 pumps can pressurize CO2 gas and transport it in a dense phase state. In the field of oil and gas exploration, dense phase CO2 is injected into oil and gas wells to increase oil recovery. In addition, it can also be widely used in chemical, food processing and pharmaceutical fields. Radial sliding bearings bear radial loads through the lubricating oil film formed between the journal and the bushing, thereby reducing friction and wear. They can be widely used in heavy-duty rotating machinery such as dense phase CO2 pumps. Radial sliding bearings play a vital role in the operation of dense phase CO2 pumps, and their performance can significantly affect the operating accuracy, efficiency and life of the whole machine. Calculating the journal equilibrium position of radial sliding bearings at specific speeds and loads is a prerequisite for studying the performance of dense phase CO2 pumps. Therefore, accurate and rapid calculation of the equilibrium position of the journal of radial sliding bearings is of great significance for the research and development and application of dense phase CO2 pumps.

[0003] The existing technical solutions can be mainly divided into two types: one is to use Matlab, Python and other programming languages ​​to perform numerical calculations to obtain the equilibrium position of the journal of the radial sliding bearing; the other is to use commercial CFD software such as Fluent and UDF (user-defined function) to solve the equilibrium position of the journal of the radial sliding bearing. The first solution is more complicated to operate, requires a high level of mathematics and programming skills from the operator, and often introduces a large number of simplified assumptions, resulting in low calculation accuracy; the UDF used in the second solution often uses the idea of ​​point-by-point scanning to find the equilibrium position of the journal, and the solution efficiency is low.

[0004] Therefore, how to accurately and quickly calculate the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for solving the equilibrium position of the journal of the radial sliding bearing of a dense phase CO2 delivery pump, which can realize accurate and rapid calculation of the lubrication performance of the radial sliding bearing at a given speed and load, so as to meet the needs of actual engineering applications of dense phase CO2 delivery pumps.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for solving the equilibrium position of the journal of a radial sliding bearing of a dense phase CO2 delivery pump includes:

[0008] Constructing an oil film model of the radial sliding bearing to be studied, and determining input parameters according to the oil film model; the input parameters include horizontal offset and vertical offset of the journal;

[0009] Selecting and defining an inlet, a wall and an outlet of the oil film model to mesh the oil film model;

[0010] Select steady-state solution in the fluid simulation software, and set material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, grid interface and solution method in turn;

[0011] Initialization and the first calculation are performed in sequence in the fluid simulation software to obtain the oil film pressure distribution when the journal is in the initial position;

[0012] Set output parameters; generate a series of design points in the experimental design module of response surface optimization, and conduct corresponding experiments to obtain experimental results;

[0013] A response surface is generated based on the experimental results, and optimization is performed according to the generated response surface to obtain the equilibrium position of the journal.

[0014] Preferably, the oil film model includes a thin film portion between the journal and the bearing and a cylindrical portion of the oil inlet; the journal has a diameter of 79.8 mm and a length of 100 mm; the bearing has a diameter of 80 mm and a length of 100 mm; the oil inlet has a diameter of 4 mm and a height of 5 mm.

[0015] Preferably, the initial value of the horizontal offset is set to 0.03 mm, and the initial value of the vertical offset is set to 0.04 mm.

[0016] Preferably, meshing the oil film model includes:

[0017] The film portion is divided into 720 equal parts in the circumferential direction, 250 equal parts in the axial direction, and 3 equal parts in thickness; the oil inlet is divided into 40 equal parts in the circumferential direction and 20 equal parts in height.

[0018] Preferably, a steady-state solution is selected in the fluid simulation software, and material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, grid interface and solution method are set in sequence, including:

[0019] Set the liquid phase material according to the N32 lubricating oil used, set the viscosity through UDF, introduce the viscosity-temperature effect, and set the gas phase material for the lubricating oil vapor;

[0020] Select Mixture model, select liquid phase material for the first phase, select gas phase material for the second phase, select Schnerr-Sauer model in cavitation for mass transfer, and set the vaporization pressure to 30000Pa;

[0021] Select the Laminar model and check Viscous Heating;

[0022] Set the operating pressure to 0Pa;

[0023] Set the inlet gauge pressure to 120000Pa, the temperature to 298.15K, the outlet gauge pressure to 101325Pa, the reflux total temperature to 298.15K, the journal wall to the moving wall, the speed to 3000rpm, the heat flux to 0, and the other walls to the stationary wall, the heat flux to 0;

[0024] The bearing wall surface and the bottom surface of the oil inlet are set as the interface;

[0025] The pressure-velocity coupling algorithm is selected as Coupled format. In the spatial discretization, the pressure format is selected as PRESTO!. Other flux formats are selected as first-order upwind. The number of iterations is set to 500. When the difference in mass flow rate between the inlet and outlet is less than 1%, the iteration is determined to be convergent.

[0026] Preferably, the initialization is mixed initialization.

[0027] Preferably, the output parameters include: horizontal oil film force on the journal, vertical oil film force, and the ratio of the horizontal oil film force to the vertical oil film force.

[0028] Preferably, generating a response surface based on the experimental results, and optimizing according to the generated response surface to obtain the equilibrium position of the journal, comprises:

[0029] The optimization target is set, the vertical oil film force is 4000N, the ratio of the horizontal oil film force to the vertical oil film force is 0, and the tolerance is 0.001;

[0030] Check "Verify candidate points" and calculate 3 candidate design points;

[0031] A candidate design point closest to the optimization target is selected, that is, the horizontal offset is 0.036977 mm and the vertical offset is 0.029228 mm. It is verified that the corresponding vertical oil film force is 4010.7 N, and the ratio of the horizontal oil film force to the vertical oil film force is -0.0026.

[0032] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0033] The invention provides a method for solving the equilibrium position of the journal of the radial sliding bearing of a dense phase CO2 delivery pump, comprising: constructing an oil film model of the radial sliding bearing to be studied, and determining input parameters according to the oil film model; the input parameters include the horizontal offset and the vertical offset of the journal; selecting and defining the inlet, wall and outlet of the oil film model to mesh the oil film model; selecting steady-state solution in fluid simulation software, and sequentially setting material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, mesh interface and solution method; sequentially performing initialization and first calculation in the fluid simulation software to obtain the oil film pressure distribution of the journal at the initial position; setting output parameters; generating a series of design points in an experimental design module of response surface optimization, and performing corresponding experiments to obtain experimental results; generating a response surface based on the experimental results, and optimizing according to the generated response surface to obtain the equilibrium position of the journal. The invention is simple to operate, does not involve complex mathematical derivation and programming, and almost does not introduce simplified assumptions, can comprehensively consider the influence of factors such as viscous heating, viscosity-temperature effect, multiphase flow, etc., is more consistent with actual conditions, and has high calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 A flow chart of a method provided by an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of a solution process provided by an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of an oil film model provided by an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the grid division of the oil film model provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The purpose of the present invention is to provide a solution method for the equilibrium position of the journal of the radial sliding bearing of a dense phase CO2 delivery pump. The method is simple to operate, does not involve complex mathematical derivation and programming, and almost does not introduce simplified assumptions. The influence of factors such as viscous heating, viscosity-temperature effect, and multiphase flow can be comprehensively considered, which is more consistent with the actual situation and has high calculation accuracy.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Figure 1 A flow chart of a method provided by an embodiment of the present invention, such as Figure 1 As shown, the present invention provides a method for solving the equilibrium position of the journal of the radial sliding bearing of a dense phase CO2 delivery pump, comprising:

[0043] Step 100: constructing an oil film model of the radial sliding bearing to be studied, and determining input parameters according to the oil film model; the input parameters include horizontal offset and vertical offset of the journal;

[0044] Step 200: Select and define the inlet, wall and outlet of the oil film model to mesh the oil film model;

[0045] Step 300: Select steady-state solution in the fluid simulation software, and set material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, grid interface and solution method in sequence;

[0046] Step 400: performing initialization and first calculation in sequence in the fluid simulation software to obtain the oil film pressure distribution when the journal is in the initial position;

[0047] Step 500: setting output parameters; generating a series of design points in the experimental design module of response surface optimization, and performing corresponding experiments to obtain experimental results;

[0048] Step 600: Generate a response surface based on the experimental results, and perform optimization according to the generated response surface to obtain the equilibrium position of the journal.

[0049] Specifically, the process of this embodiment is as follows Figure 2 As shown, the specific steps include:

[0050] Step 1: Use the DesignModeler module of the Workbench platform to construct an oil film model of the radial sliding bearing to be studied, preferably, Figure 3As shown, the oil film model includes a thin film part (1) between the journal and the bearing shell and a cylindrical part (2) of the oil inlet, the journal has a diameter of 79.8 mm and a length of 100 mm, the bearing shell has a diameter of 80 mm and a length of 100 mm, the oil inlet has a diameter of 4 mm and a height of 5 mm;

[0051] Step 2: Set the horizontal offset and vertical offset of the journal in step 1 as input parameters, P1 and P2 respectively, and set initial values ​​to prepare for response surface optimization. Preferably, the initial value of the horizontal offset of the journal is set to 0.03 mm, and the initial value of the vertical offset is set to 0.04 mm;

[0052] Step 3: Select and define the inlet, wall and outlet of the oil film model in the Mesh module, and mesh the oil film model. Figure 4 As shown, the film is divided into 720 equal parts in the circumferential direction, 250 equal parts in the axial direction, and 3 equal parts in thickness, and the oil inlet is divided into 40 equal parts in the circumferential direction and 20 equal parts in height;

[0053] Step 4: Select steady-state solution in Fluent;

[0054] Step 5: Set material properties in Fluent. Preferably, set the liquid phase material according to the N32 lubricant used, set the viscosity through UDF to introduce the viscosity-temperature effect, and set the gas phase material for the lubricant vapor;

[0055] Step 6: Set up multiphase flow in Fluent. Preferably, select Mixture model, select liquid phase material for the first phase, select gas phase material for the second phase, select Schnerr-Sauer model in cavitation for mass transfer, and set the vaporization pressure to 30000Pa;

[0056] Step 7: Set the viscosity model in Fluent. Preferably, select the Laminar model and check ViscousHeating.

[0057] Step 8: Set the operating pressure in Fluent. Preferably, set the operating pressure to 0Pa.

[0058] Step 9: Set boundary conditions in Fluent. Preferably, set the inlet gauge pressure to 120000Pa, the temperature to 298.15K, the outlet gauge pressure to 101325Pa, the reflux total temperature to 298.15K, the journal wall to the moving wall, the speed to 3000rpm, the heat flux to 0, and the other walls to the stationary wall, with a heat flux of 0;

[0059] Step 10: Set the grid interface in Fluent. Preferably, the bearing wall and the bottom surface of the oil inlet are set as the interface.

[0060] Step 11: Set the solution method in Fluent. Preferably, the pressure-velocity coupling algorithm selects Coupled format. In the spatial discretization, the pressure format selects PRESTO! . Other flux formats select first-order upwind. The number of iterations is set to 500. When the difference in mass flow rate between the inlet and outlet is less than 1%, the iteration is considered to have converged.

[0061] Step 12: Initialize in Fluent, preferably, choose mixed initialization;

[0062] Step 13: Perform the first calculation in Fluent to obtain the oil film pressure distribution of the journal at the initial position;

[0063] Step 14: Set the output parameters in CFD Post. Preferably, the horizontal oil film force acting on the journal is set to Fx = force_x()@moving_wall, the vertical oil film force is set to Fy = force_y()@moving_wall, the ratio of the two is set to Ratio of Fx to Fy = Fx / Fy, and three variables are set as output parameters, namely P3, P4 and P5;

[0064] Step 15: Generate a series of design points in the experimental design module of the response surface optimization and conduct corresponding experiments. Preferably, select Central Composite Design and Rotatable as the experimental design type, and set the value range of P1 and P2 to 0-0.05 mm.

[0065] Step 16: Generate response surface based on experimental results;

[0066] Step 17: Optimize based on the generated response surface to obtain the equilibrium position of the journal. Preferably, set the optimization target to P4=4000N, P5=0, and the tolerance is 0.001. Check "Verify candidate points" and calculate 3 candidate design points. Select the candidate design point closest to the optimization target, that is, P1=0.036977mm, P2=0.029228mm, and verify the corresponding P4=4010.7N, P5=-0.0026.

[0067] In the DesignModeler module of the present invention, the horizontal offset and vertical offset of the journal of the radial sliding bearing are set as input parameters to achieve parameterization; in CFD Post, the horizontal oil film force, the vertical oil film force and the ratio thereof acting on the journal are set as output parameters to achieve parameterization; and response surface optimization is used to optimize the horizontal offset and vertical offset of the journal with "the vertical oil film force acting on the journal is equal to the load, and the ratio of the horizontal oil film force to the vertical oil film force is equal to 0" as the optimization target, thereby achieving accurate and rapid calculation of the journal equilibrium position of the radial sliding bearing of the dense phase CO2 delivery pump under a given speed and load.

[0068] The beneficial effects of the present invention are as follows:

[0069] (1) The technical solution proposed in the present invention is simple to operate, does not involve complex mathematical derivation and programming, and almost does not introduce simplified assumptions. It can comprehensively consider the influence of factors such as viscous heating, viscosity-temperature effect, and multiphase flow, which is more consistent with the actual situation and has high calculation accuracy.

[0070] (2) The technical solution proposed in the present invention can avoid the huge amount of calculation brought by the point-by-point scanning method with the help of the response surface optimization algorithm, thereby significantly improving the solution efficiency while ensuring the calculation accuracy.

[0071] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0072] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for solving the equilibrium position of the journal of the radial sliding bearing of a dense phase CO2 delivery pump, characterized in that: include: Constructing an oil film model of the radial sliding bearing to be studied, and determining input parameters according to the oil film model; The input parameters include the horizontal offset and the vertical offset of the journal; Selecting and defining an inlet, a wall and an outlet of the oil film model to mesh the oil film model; Select steady-state solution in the fluid simulation software, and set material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, grid interface and solution method in turn; Initialization and the first calculation are performed in sequence in the fluid simulation software to obtain the oil film pressure distribution when the journal is in the initial position; Set output parameters; Generate a series of design points in the experimental design module of response surface optimization, conduct corresponding experiments, and obtain experimental results; A response surface is generated based on the experimental results, and optimization is performed according to the generated response surface to obtain the equilibrium position of the journal.

2. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 1 is characterized in that: The oil film model includes a thin film part between the journal and the bearing shell and a cylindrical part of the oil inlet; the diameter of the journal is 79.8 mm and the length is 100 mm; the diameter of the bearing shell is 80 mm and the length is 100 mm; the diameter of the oil inlet is 4 mm and the height is 5 mm.

3. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 1 is characterized in that: The initial value of the horizontal offset is set to 0.03 mm, and the initial value of the vertical offset is set to 0.04 mm.

4. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 2 is characterized in that: Meshing of the oil film model includes: The film portion is divided into 720 equal parts in the circumferential direction, 250 equal parts in the axial direction, and 3 equal parts in thickness; the oil inlet is divided into 40 equal parts in the circumferential direction and 20 equal parts in height.

5. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 2 is characterized in that: Select steady-state solution in the fluid simulation software, and set material properties, multiphase flow, viscosity model, operating pressure, boundary conditions, grid interface and solution method in turn, including: Set the liquid phase material according to the N32 lubricating oil used, set the viscosity through UDF, introduce the viscosity-temperature effect, and set the gas phase material for the lubricating oil vapor; Select Mixture model, select liquid phase material for the first phase, select gas phase material for the second phase, select Schnerr-Sauer model in cavitation for mass transfer, and set the vaporization pressure to 30000Pa; Select the Laminar model and check Viscous Heating; Set the operating pressure to 0Pa; Set the inlet gauge pressure to 120000Pa, the temperature to 298.15K, the outlet gauge pressure to 101325Pa, the reflux total temperature to 298.15K, the journal wall to the moving wall, the speed to 3000rpm, the heat flux to 0, and the other walls to the stationary wall, the heat flux to 0; The bearing wall surface and the bottom surface of the oil inlet are set as the interface; The pressure-velocity coupling algorithm is selected as Coupled format. In the spatial discretization, the pressure format is selected as PRESTO!. Other flux formats are selected as first-order upwind. The number of iterations is set to 500. When the difference in mass flow rate between the inlet and outlet is less than 1%, the iteration is determined to be convergent.

6. The method for solving the journal equilibrium position of the radial sliding bearing of a dense phase CO2 delivery pump according to claim 1 is characterized in that: The initialization is mixed initialization.

7. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 1 is characterized in that: The output parameters include: the horizontal oil film force on the journal, the vertical oil film force, and the ratio of the horizontal oil film force to the vertical oil film force.

8. The method for solving the equilibrium position of the journal of the radial sliding bearing of the dense phase CO2 delivery pump according to claim 2 is characterized in that: A response surface is generated based on the experimental results, and optimization is performed according to the generated response surface to obtain the equilibrium position of the journal, including: The optimization target is set, the vertical oil film force is 4000N, the ratio of the horizontal oil film force to the vertical oil film force is 0, and the tolerance is 0.001; Check "Verify candidate points" and calculate 3 candidate design points; A candidate design point closest to the optimization target is selected, that is, the horizontal offset is 0.036977 mm and the vertical offset is 0.029228 mm. It is verified that the corresponding vertical oil film force is 4010.7 N, and the ratio of the horizontal oil film force to the vertical oil film force is -0.0026.

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