Method for calculating axial lubrication thrust of shaftless canned motor pump and method for judging gap wear

Abstract

The application relates to a method for calculating an axial lubrication thrust of a shaftless shield pump and a method for judging gap wear, and relates to the technical field of the shaftless shield pump, and comprises the following steps: a thickness ratio obtaining step: obtaining a lubrication film thickness ratio m formed between a rotor end face and a corresponding end face of a pump body; a thrust obtaining step: obtaining an axial lubrication thrust F Lu , wherein, ω is a rotor rotation angular velocity, and the unit is rad / s; μ is a fluid viscosity, and the unit is Pa.s; B is an equivalent width, and the unit is m; d t is an orifice diameter, and the unit is m, D t is a lubrication film diameter, and the unit is m, h min is a minimum distance between the rotor end face and the corresponding end face of the pump body, and the unit is mu.m. The application has the advantages that the axial lubrication thrust of the shaftless shield pump can be calculated.

Description

Technical Field

[0001] This application relates to the technical field of shaftless canned motor pumps, and in particular to a method for calculating the axial lubrication thrust of shaftless canned motor pumps and a method for judging clearance wear. Background Technology

[0002] When a shaftless canned motor pump is in operation, its rotor is completely submerged in the pumping medium, and the bottom of the rotor and the corresponding end face of the pump body form an axial friction pair. This friction pair relies on the working medium to form a lubricating film, which, under ideal operating conditions, can form a complete hydrodynamic lubricating film, thereby significantly reducing wear and extending service life. Therefore, how to calculate the axial lubrication thrust of a shaftless canned motor pump becomes a problem that needs to be solved. Summary of the Invention

[0003] To address the shortcomings of existing technologies, one of the objectives of this application is to provide a method for calculating the axial lubrication thrust of a shaftless canned motor pump and a method for judging clearance wear, which has the advantage of being able to calculate the axial lubrication thrust of a shaftless canned motor pump.

[0004] The above-mentioned objective of this application is achieved through the following technical solution:

[0005] A method for calculating the axial lubrication thrust of a shaftless canned motor pump includes the following steps: Thickness ratio acquisition step: obtaining the thickness ratio m of the lubrication film formed between the rotor end face and the corresponding end face of the pump body; Thrust acquisition step: obtaining the axial lubrication thrust. F Lu , in, Rotor rotational angular velocity, measured in rad / s; μ Fluid viscosity, unit: (V / V) B represents the equivalent width, measured in meters (m). The diameter of the orifice is in meters (m). It is the diameter of the lubricating film, in meters (m). This is the minimum distance between the rotor end face and the corresponding end face of the pump body, in μm.

[0006] In a preferred embodiment, this application can be further configured such that, in the thickness ratio acquisition step... in, The minimum distance between the rotor end face and the corresponding end face of the pump body, in units of... , This is the maximum distance between the rotor end face and the corresponding end face of the pump body, in μm.

[0007] In a preferred example, this application can be further configured as follows: in, The roughness of the rotor end face is expressed in units of 1000 m². This indicates the roughness of the corresponding end face of the pump body, measured in units of... , It is the diameter of the lubricating film, in meters (m). β The rotor tilt angle.

[0008] In a preferred example, this application can be further configured as follows: in, F t It is the axial force acting on the rotor of the shaftless shielded pump, and its unit is N; F r It is the radial force acting on the rotor of the shaftless shielded pump, and its unit is N.

[0009] This application also discloses a method for judging the clearance wear of a shaftless shielded pump, wherein the axial lubrication thrust is obtained by using the above-mentioned method for calculating the axial lubrication thrust of a shaftless shielded pump. ,Compare and the axial force acting on the rotor of the shaftless canned pump ,if This indicates that the fluid lubrication film is sufficient to withstand the external axial load, the friction pair is in a disengaged state, and no wear will occur at this location; if This indicates that the fluid lubrication film has insufficient load-bearing capacity, and wear will occur at this location.

[0010] This application has the following advantages:

[0011] By calculating the axial lubrication thrust of the shaftless canned pump and comparing it with the axial force acting on the rotor of the shaftless canned pump, it is possible to accurately determine whether wear will occur. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the rotor and pump body assembly structure of this application.

[0013] Figure 2 This is a schematic diagram showing the tilting of the rotor under stress according to this application.

[0014] Figure 3 This is a schematic diagram of the lubricating film structure of this application.

[0015] Attached image reference numerals: 1. Lubricating film. Detailed Implementation

[0016] The present application will be further described in detail below with reference to the accompanying drawings.

[0017] Reference Figures 1-3 The present application discloses a method for calculating the axial lubrication thrust of a shaftless shielded pump, which includes the following steps: Thickness ratio acquisition step: obtaining the thickness ratio m of the lubricating film 1 formed between the rotor end face and the corresponding end face of the pump body;

[0018] Thrust acquisition steps: Obtain axial lubrication thrust , in, ω represents the angular velocity of the rotor, measured in rad / s. Where is the fluid viscosity, in Pa·s; B is the equivalent width, in meters. The diameter of the orifice is in meters (m). It is the diameter of the lubricating film, in meters (m). This is the minimum distance between the rotor end face and the corresponding end face of the pump body, in μm.

[0019] In the thickness ratio acquisition step in, This is the minimum distance between the rotor end face and the corresponding end face of the pump body, in μm. This is the maximum distance between the rotor end face and the corresponding end face of the pump body, in μm.

[0020] in, This indicates the roughness of the rotor end face, measured in μm. This indicates the roughness of the corresponding end face of the pump body, measured in μm. It is the diameter of the lubricating film, in meters (m). β The rotor tilt angle;

[0021] in, It is the axial force acting on the rotor of the shaftless shielded pump, and its unit is N; It is the radial force acting on the rotor of the shaftless shielded pump, and its unit is N.

[0022] This application also discloses a method for judging the clearance wear of a shaftless shielded pump, wherein the axial lubrication thrust is obtained by using the above-mentioned method for calculating the axial lubrication thrust of a shaftless shielded pump. ,Compare and the axial force acting on the rotor of the shaftless canned pump ,if This indicates that the fluid lubrication film 1 is sufficient to withstand the external axial load, the friction pair is in a separated state, and no wear will occur at this location; if This indicates that the fluid lubrication film 1 has insufficient load-bearing capacity, and wear will occur at this location.

[0023] Taking a certain type of shaftless canned motor pump as an example: Let the annular end face at the bottom of the rotor of the shaftless canned motor pump be surface A, and the corresponding annular end face of the pump body be surface B. The two constitute an axial friction pair.

[0024] S1: If the CFD solver ANSYS CFX is used, the axial force acting on the rotor of the shaftless canned pump can be calculated. =96N, radial force =2.8N.

[0025] S2: Due to axial and radial forces, the rotor axis is forced to deviate from the centerline, causing the rotor to tilt. Rotor tilt angle. β It can be calculated using formula (1):

[0026]

[0027] In the formula, It is axial force, and the unit is N; This is the radial force, measured in N. The calculated rotor tilt angle is 1.67°.

[0028] S3: According to step S2, the rotor tilting causes the parallel gap between surface A and surface B to be broken, forming a wedge-shaped gap.

[0029] Assuming a lubricating film 1 is formed between surface A and surface B, the minimum gap between them is... Both surface A and surface B are made of engineering plastics with a surface roughness of 3.25 μm.

[0030]

[0031] In the formula, Ra A This represents the roughness of surface A, measured in μm. Ra B This represents the surface roughness of surface B, measured in μm. The calculated minimum clearance between surfaces A and B is... h min =0.000023m.

[0032] The maximum gap between surface A and surface B is h max :

[0033]

[0034] In the formula, D t The diameter of the lubricating film is 0.05m, and the maximum gap between surface A and surface B is calculated to be 0.00148m.

[0035] S4: According to step S3, the thickness ratio m of lubricating film 1 is:

[0036]

[0037] The calculated thickness ratio of the lubricating film 1 to m is 64.35.

[0038] S5: The formula for calculating axial lubrication thrust is:

[0039]

[0040] In the formula, ω The rotor's angular velocity is 576 rad / s; μ The fluid viscosity is 0.1 Pa·s; d t B is the orifice diameter, which is 0.003m; B is the equivalent width, which is 0.0235m. The calculated axial lubrication thrust is 693.83N.

[0041] S6: The axial force calculated in step S1 F r The axial lubrication thrust calculated in step S5 F Lu Comparison:

[0042] This indicates that the fluid lubrication film 1 is sufficient to bear the external axial load, the friction pair is in a separated state, and no wear will occur at this position.

[0043] The implementation principle of this embodiment is as follows: by calculating the axial lubrication thrust of the shaftless canned pump and comparing it with the axial force acting on the rotor of the shaftless canned pump, it is possible to accurately determine whether wear will occur.

[0044] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for calculating the axial lubrication thrust of a shaftless shielded pump, characterized in that: The steps include: Thickness ratio acquisition step: obtaining the thickness ratio m of the lubricating film formed between the rotor end face and the corresponding end face of the pump body; Thrust acquisition step: obtaining the axial lubrication thrust. F Lu， in, oh ω represents the angular velocity of the rotor, measured in rad / s. m Where is the fluid viscosity, in Pa·s; B is the equivalent width, in meters. d t The diameter of the orifice is in meters (m). D t It is the diameter of the lubricating film, in meters (m). This is the minimum distance between the rotor end face and the corresponding end face of the pump body, in μm.

2. The method for calculating the axial lubrication thrust of a shaftless shielded pump according to claim 1, characterized in that: In the thickness ratio acquisition step ,in, This is the minimum distance between the rotor end face and the corresponding end face of the pump body, in μm. This is the maximum distance between the rotor end face and the corresponding end face of the pump body, in μm.

3. The method for calculating the axial lubrication thrust of a shaftless shielded pump according to claim 2, characterized in that: in, This indicates the roughness of the rotor end face, measured in μm. This indicates the roughness of the corresponding end face of the pump body, measured in μm. D t It is the diameter of the lubricating film, in meters (m). β The rotor tilt angle.

4. The method for calculating the axial lubrication thrust of a shaftless shielded pump according to claim 3, characterized in that: in, F t It is the axial force acting on the rotor of the shaftless shielded pump, and its unit is N; F r It is the radial force acting on the rotor of the shaftless shielded pump, and its unit is N.

5. A method for judging clearance wear in a shaftless shielded pump, characterized in that: The axial lubrication thrust obtained by using the calculation method for axial lubrication thrust of a shaftless shielded pump as described in any one of claims 1-4 ,Compare and the axial force acting on the rotor of the shaftless canned pump if This indicates that the fluid lubrication film is sufficient to withstand the external axial load, the friction pair is in a disengaged state, and no wear will occur at this location; if This indicates that the fluid lubrication film has insufficient load-bearing capacity, and wear will occur at this location.

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