A two-phase flow test system and method for tilting pad directional lubrication bearing

Abstract

The present invention relates to the technical field of sliding bearings, and in particular to a two-phase flow test system and method for tilting pad directional lubrication bearings. By setting a two-phase flow mixer, a uniform two-phase flow can be generated, and the precise control of the two-phase flow gas volume fraction in the bearing experiment can be achieved, which is crucial to the optimization of bearing performance and realizes the transformation of bearing performance research from qualitative research to quantitative research; by setting a two-phase flow sampling and separation device, oil and gas separation can be achieved, and the two-phase flow sampling and separation device can realize accurate measurement of the two-phase flow gas volume fraction at the bearing inlet; the oil-gas mixing phenomenon at the bearing inlet is complex, and accurate two-phase flow gas volume fraction measurement helps to deeply understand and explain the oil poverty phenomenon and its influence on the static and dynamic performance of the bearing. The test system and method proposed in the present invention provide experimental verification means for the basic theoretical research on oil poverty and cavitation, and will promote the development of the basic theory of oil poverty and cavitation.

Description

Technical Field

[0001] The invention relates to the technical field of sliding bearings, and in particular to a two-phase flow test system and method for a tilting pad directional lubrication bearing. Background Art

[0002] In recent years, high efficiency, energy saving and high stability have become the primary prerequisites for the development of modern industry. Tilting pad sliding bearings have the advantages of large load-bearing capacity, high stability and impact resistance, and are widely used in high-speed and precise rotating machinery such as large gas turbines and steam turbine units.

[0003] The working state of large high-speed tilting pad radial bearings is generally turbulent. Compared with the laminar state, the friction loss of turbulent flow will increase to a certain extent and the maximum temperature of the pad surface will decrease. Tilting pad bearings can be divided into two types according to the lubrication method: one is oil-rich lubrication type, and the other is directional lubrication type. Compared with the oil-rich lubrication type, the directional lubrication type can control the amount of lubricating oil flowing to the pad surface to achieve the purpose of reducing friction loss and pad surface temperature. Therefore, compared with the oil-rich type, the directional lubrication type has obvious advantages and has become the focus of research in recent years.

[0004] Existing tilting pad directional lubrication bearing test technology usually adopts single-phase flow oil supply, while actual bearings usually have two-phase flow during operation. In directional lubrication bearings, when the oil supply of the system is reduced, air or bubbles will enter the bearing inlet. At this time, the bearing is in an oil-poor state and multiphase flow or mixed bubble phenomenon occurs, thereby changing the static and dynamic characteristics of the bearing. This state can also be regarded as a kind of cavitation phenomenon. In order to study the influence of cavitation on the performance of tilting pad sliding bearings, a system and method suitable for two-phase flow testing of tilting pad sliding bearings is needed to study the influence of preset gas volume fraction in two-phase flow on bearing performance (including oil film pressure, oil film thickness, pad surface temperature, fluid state and friction power consumption, etc.) under different loads and speeds, and then control and optimize the gas volume fraction in the two-phase flow through the test results. At present, there is a lack of relevant test equipment and methods for effective testing, which is not what technical personnel in this field want to see. Summary of the invention

[0005] In view of the above problems, the present invention discloses a two-phase flow test system for a tilting pad directional lubrication bearing, which includes a driving device, a rotating shaft, a loading device, a two-phase flow mixer, a test bearing and a two-phase flow sampling and separation device;

[0006] The driving device is connected to the rotating shaft to drive the rotating shaft, the test bearing is mounted on the rotating shaft, and the loading device is mounted on the test bearing to load a radial load on the test bearing;

[0007] The two-phase flow mixer comprises a mixer body, a compressed air source and an oil pump, an air inlet and an oil inlet are arranged at one end of the mixer body, and a two-phase flow outlet is arranged at the other end, the air source is connected to the air inlet through an air inlet pipe, the oil pump is connected to the oil inlet through an oil inlet pipe, and flow detection devices are arranged on the air inlet pipe and the oil inlet pipe, at least two cavities are arranged in sequence in the mixer body along the flow direction of the oil-gas two-phase flow, and at least one partition with a plurality of through holes is arranged in each of the cavities, and two adjacent cavities are connected through a narrow channel, and the two-phase flow outlet is connected to the test bearing;

[0008] The test bearing includes multiple bearing shells, and an oil hole is opened at the entrance of the bearing shell. The two-phase flow sampling and separation device is connected to the oil hole through a sampling tube, and a stop valve is provided on the sampling tube. The two-phase flow sampling and separation device is used to sample the oil-gas two-phase flow from the oil hole and perform oil-gas separation on the sampled oil-gas two-phase flow.

[0009] Preferably, the two-phase flow sampling and separation device comprises a container, a two-phase flow pipeline and a test tube;

[0010] The container contains water, the test tube is inverted in the container and filled with water, the outlet end of the two-phase flow pipeline extends from the container into the test tube, and the inlet end of the two-phase flow pipeline is connected to the sampling tube.

[0011] Preferably, the test tube is provided with a scale.

[0012] Preferably, the driving device comprises a driving motor and a gear box, the driving motor is connected to the gear box via a coupling, and the gear box is connected to the rotating shaft via a coupling.

[0013] Preferably, the system further comprises a support bearing, and the support bearing is used to support the rotating shaft.

[0014] Preferably, the mixer body is made of metal or glass.

[0015] Preferably, the partition is made of stainless steel.

[0016] Preferably, the diameter of the through holes on the partition is 2.5-3.5 mm.

[0017] Preferably, a leading groove is provided on the bearing shell.

[0018] The present invention also discloses a two-phase flow test method for a tilting pad directional lubrication bearing, wherein, based on the above system, the method comprises the following steps:

[0019] Step S1, turning on the compressed gas source and the oil pump to quantitatively deliver an oil-gas two-phase flow to the test bearing according to a preset first gas volume fraction through the flow detection device and the mixer body;

[0020] Step S2, turning on the driving device and the loading device, wherein the driving device drives the test bearing to rotate via the rotating shaft, and the loading device loads a radial load to the test bearing;

[0021] Step S3, obtaining the relationship between the first gas volume fraction and various bearing performance parameters under different loads and rotation speeds, wherein the various bearing performance parameters include the oil film pressure, oil film thickness, bearing surface temperature, fluid state and friction power consumption of the bearing;

[0022] Step S4, opening the stop valve to sample the oil-gas two-phase flow on the test bearing using the two-phase flow sampling and separation device and obtaining the second gas volume fraction of the sampled oil-gas two-phase flow;

[0023] Step S5, adjusting the first gas volume fraction according to the relationship between the first gas volume fraction and various bearing performance parameters and the second gas volume fraction.

[0024] Compared with the prior art, the above invention has the following advantages or beneficial effects:

[0025] 1. The two-phase flow mixer proposed in the present invention can generate uniform two-phase flow, realizing precise control of the volume fraction of the two-phase flow gas in the bearing experiment, which is crucial to the optimization of bearing performance and realizes the transformation of bearing performance research from qualitative research to quantitative research.

[0026] Second, the present invention proposes a two-phase flow sampling and separation device, which can realize oil-gas separation and is applied to the two-phase flow test of tilting pad directional lubrication bearings, and can realize the accurate measurement of the two-phase flow gas volume fraction at the bearing inlet. The oil-gas mixing phenomenon at the bearing inlet is complex, and accurate two-phase flow gas volume fraction measurement helps to deeply understand and explain the oil-poor phenomenon and its impact on the static and dynamic performance of the bearing.

[0027] 3. The experimental system and method proposed in the present invention provide experimental verification means for the basic theoretical research on oil poverty and cavitation, and will promote the development of the basic theory of oil poverty and cavitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention and its features, appearance and advantages will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings. The same reference numerals indicate the same parts in all the drawings. The drawings are not drawn to scale, and emphasis is placed on illustrating the subject matter of the present invention.

[0029] Figure 1 is a cross-sectional view of a two-phase flow test system for a tilting pad directional lubrication bearing according to an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of the main structure of the two-phase flow test system for the tilting pad directional lubrication bearing according to an embodiment of the present invention;

[0031] Figure 3 is a schematic structural diagram of a two-phase flow mixer in an embodiment of the present invention;

[0032] Figure 4 is a cross-sectional view of a mixer body in an embodiment of the present invention;

[0033] Figure 5 is a schematic structural diagram of a bearing shell in a test bearing in an embodiment of the present invention;

[0034] Figure 6 is a structural schematic diagram of the initial state of the two-phase flow sampling and separation device in an embodiment of the present invention;

[0035] Figure 7 It is a schematic diagram of the structure of the two-phase flow sampling and separation device after oil and gas stratification in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to the accompanying drawings and specific embodiments, but is not intended to be a limitation of the present invention.

[0037] like Figures 1 to 7As shown, the present invention discloses a two-phase flow test system for a tilting pad directional lubrication bearing. Specifically, the two-phase flow test system for a tilting pad directional lubrication bearing comprises a driving device, a rotating shaft 3, a loading device 5 (such as a radial bearing), a two-phase flow mixer 7, a test bearing 6 (the test bearing 6 is a tilting pad directional lubrication bearing) and a two-phase flow sampling and separation device 8; the driving device is connected to the rotating shaft 3 to drive the rotating shaft 3 to rotate, the test bearing 6 is installed on the rotating shaft 3, and the loading device 5 is installed on the test bearing 6 to load a radial load on the test bearing 6; The two-phase flow mixer 7 includes a mixer body 73, a compressed air source 71 and an oil pump 72. The compressed air source 71 includes an air compressor and an air source connected to the air compressor. An air inlet 731 (i.e., a dry gas inlet) and an oil inlet 732 (i.e., a lubricating oil inlet) are provided at one end of the mixer body 73, and a two-phase flow outlet 735 is provided at the other end. The compressed air source 71 is connected to the air inlet 731 through an air inlet pipe, and the oil pump 72 is connected to the oil inlet 732 through an oil inlet pipe. Flow meters 75 are provided on both the air inlet pipe and the oil inlet pipe to measure the flow of the oil. The gas flow rate and lubricating oil flow rate flowing into the mixer body 73 within a certain period of time can be calculated, and then the oil-gas ratio can be controlled to achieve quantitative supply; at least two cavities are arranged in sequence in the mixer body 73 along the flow direction of the oil-gas two-phase flow, and each cavity is provided with at least one partition 733 with multiple through holes, and the two adjacent cavities are connected through a narrow channel 734 (the two adjacent cavities and the narrow channel together form an H-shaped structure), and the two-phase flow outlet 735 is connected to the test bearing 6 to provide the test bearing 6 with a uniformly mixed oil-gas two-phase flow. The test bearing 6 comprises a plurality of bearing shells 31, and an oil hole 312 is provided at the entrance of the bearing shell 31. The two-phase flow sampling and separation device 8 is connected to the oil hole 312 from the side of the bearing shell 31 through a sampling tube 81 (i.e., the mixed liquid flowing into the oil hole 312 on the side of the bearing shell 31 flows out through the sampling tube 81), and a stop valve 82 is provided on the sampling tube 81. The stop valve 82 is used to control the flow of the oil-gas two-phase flow. The above-mentioned two-phase flow sampling and separation device 8 is used to sample the oil-gas two-phase flow from the oil hole 312 and perform oil-gas separation on the sampled oil-gas two-phase flow.

[0038] Specifically, the two-phase flow sampling and separation device 8 includes a container 84, a two-phase flow pipe 83 and a test tube 85; the container 84 is filled with water, the test tube 85 is inverted in the container 84 and filled with water using the communicating vessel principle, the outlet end of the two-phase flow pipe 83 extends from the container 84 into the test tube 85, the inlet end of the two-phase flow pipe 83 is connected to the sampling tube 81, and the oil and gas two-phase flow passes through the pipe and is pressed into the inverted test tube 85 filled with water; a scale is set on the test tube 85 to intuitively obtain the volume ratio of oil and gas in the two-phase flow. When it is necessary to measure the gas volume fraction in the two-phase flow flowing onto the test bearing 6 within a certain period of time, open the stop valve 82, sample the two-phase flow, take samples in the same time period, and after standing for a period of time, the dry gas, lubricating oil and water will be stratified due to different densities (dry gas is at the top, lubricating oil is in the middle, and water is at the bottom), so that the accurate value of the gas volume fraction in the oil-gas two-phase flow can be measured according to the scale of the test tube 85.

[0039] In a preferred embodiment of the present invention, the above-mentioned driving device includes a driving motor 1 and a gear box 2, the driving motor 1 is connected to the gear box 2 through a coupling, and the gear box 2 is connected to the rotating shaft 3 through a coupling, thereby preventing the vibration of the driving motor 1 from being transmitted to the rotating shaft 3 and facilitating speed change.

[0040] In a preferred embodiment of the present invention, the system further comprises a support bearing 4, which is used to support the rotating shaft 3, thereby making the rotation of the rotating shaft 3 more stable. In a preferred embodiment of the present invention, two cavities are respectively arranged on the left and right sides of the mixer body 73, and two baffles 733 with uniform through holes are arranged inside each cavity, and the two cavities are connected by a narrow channel 734; the mixer body 73 is made of metal or glass, and the baffles 733 are made of stainless steel. Specifically, the mixer body 73 is made of aluminum or glass. The two-phase liquid mixer 7 provides an oil-gas two-phase flow to the test bearing 6, so it can also be called an oil-gas two-phase flow supply system for a tilting pad sliding bearing. In the two-phase flow mixer 7, a flow meter 75 and a pressure gauge 74 are installed on the pipeline connected to the gas source 71, and the gas flow rate flowing through a certain period of time can be obtained by calculation. The flow meter 75 and the pressure gauge 74 are installed on the pipeline connected to the oil pump 72, and the lubricating oil flow rate flowing through a certain period of time can be measured. The lubricating oil and dry gas are mixed inside the mixer body 73, and are fully and evenly mixed through a partition 733 with uniform through holes, and finally enter the front groove of each bearing 31 through the oil channel through the two-phase flow outlet (the only outlet), and then flow to the bearing surface, thereby realizing directional and quantitative lubrication of the test bearing 6.

[0041] Specifically, in an embodiment of the present invention, the test bearing 6 has four bearing shells 31, wherein a front groove 311 is provided on the bearing shell 31, and the oil hole 312 is adjacent to the front groove 311, and an oil-gas mixture is drawn out at the oil hole 312 to facilitate sampling and oil-gas separation by the two-phase flow sampling and separation device 8.

[0042] In a preferred embodiment of the present invention, the aperture of the through hole on the partition 733 is 2.5 to 3.5 mm (eg, 2.5 mm, 3 mm, 3.2 mm or 3.5 mm, etc.), which is conducive to the mixing of the two-phase flow.

[0043] In a specific embodiment of the present invention, the bearing structural parameters of the above-mentioned test bearing 6 are: the diameter of the test bearing 6 is 200mm, the width of the bearing 31 is 80mm, the number of bearings 31 is 4, the nominal clearance of the radial bearing is 150μm, the preload is 0, the support position offset is 55%, the support position is (57, 147, 237, 327), the arc length of the bearing 31 is 86°, and the thickness of the bearing 31 is 39mm; the material properties of the bearing 31 and the babbitt alloy layer of the test bearing 6 are 7890 / 7270kg / m 3 , Young's modulus 206 / 54GPa, Poisson's ratio 0.3 / 0.3, thermal expansion coefficient 11 / 22×10 -6 , thermal conductivity 53.15 / 64.06W / m / K, specific heat capacity 460J / (kg K). The lubricating oil in the oil pump 72 is aviation material HP-8A aviation jet lubricating oil, with a density of 885kg / m 3 , specific heat capacity is 1870-1880 J / kg / ℃, viscosity at 20℃ is 26.55 mPa.s, viscosity at 50℃ is 8.3 mPa.s, thermal conductivity is 0.141 W / m / K. The density of dry gas provided by gas source 71 is 1 kg / m 3 , viscosity is 1.81×10 -2 mPa.s.

[0044] In addition, the present invention also discloses a two-phase flow test method for a tilting pad directional lubrication bearing. Specifically, the test method is based on the above-mentioned two-phase flow test system for the tilting pad directional lubrication bearing, and the method comprises the following steps:

[0045] Step S1, turning on the compressed gas source and the oil pump to quantitatively deliver the oil-gas two-phase flow to the test bearing according to a preset first gas volume fraction through the flow meter and the mixer body.

[0046] Specifically, the gas volume fraction is calculated using formula (1):

[0047]

[0048] Among them, Vg is the gas volume, V l is the fluid volume, and α is the gas volume fraction.

[0049] Step S2, turning on the driving device and the loading device, wherein the driving device drives the test bearing to rotate via the rotating shaft, and the loading device applies a radial load to the test bearing;

[0050] Step S3, obtaining the relationship between the first gas volume fraction and various bearing performance parameters under different radial loads and rotation speeds, wherein the performance parameters include the oil film pressure, oil film thickness, bearing surface temperature, fluid state and friction power consumption of the bearing.

[0051] Step S4, opening the stop valve to sample the oil-gas two-phase flow on the test bearing using the two-phase flow sampling and separation device and obtain the second gas volume fraction of the sampled oil-gas two-phase flow.

[0052] Specifically, the second gas volume fraction may also be calculated using the above formula (1).

[0053] It should be noted here that the first gas volume fraction is the preset gas volume fraction of the oil-gas two-phase flow. However, after the two-phase flow enters the test bearing, a small amount of gas will overflow because the bearing chamber cannot be completely sealed. In addition, the oil-gas two-phase flow at the outlet of the previous bearing and the new oil-gas two-phase flow entering the next bearing will affect each other. The actual two-phase flow situation at each bearing inlet is complex and changeable. Therefore, it is necessary to measure the second gas volume fraction at the bearing inlet, which is helpful to understand the oil-poor degree of the tilting pad directional lubrication bearing and optimize the static and dynamic performance.

[0054] Step S5, adjusting the first gas volume fraction according to the relationship between the first gas volume fraction and various bearing performance parameters and the second gas volume fraction.

[0055] It is not difficult to find that this embodiment is a method embodiment corresponding to the embodiment of the two-phase flow test system for tilting pad directional lubrication bearings described above, and this embodiment can be implemented in conjunction with the embodiment of the two-phase flow test system for tilting pad directional lubrication bearings described above. The relevant technical details mentioned in the embodiment of the two-phase flow test system for tilting pad directional lubrication bearings described above are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied in the embodiment of the two-phase flow test system for tilting pad directional lubrication bearings described above.

[0056] In summary, the two-phase flow test system and method for tilting pad directional lubrication bearings disclosed in the present invention can control the gas volume fraction in the two-phase liquid at the inlet of the two-phase flow mixer, and can also detect the gas volume fraction in the mixed liquid after entering the bearing lubrication. On the one hand, it realizes the transformation of bearing performance research from qualitative research to quantitative research, and on the other hand, it helps to deeply understand and explain the oil poverty phenomenon and its influence on the static and dynamic performance of the bearing.

[0057] Those skilled in the art should understand that those skilled in the art can implement variations by combining the prior art and the above embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present invention, and will not be described in detail here.

[0058] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A two-phase flow test system for tilting pad directional lubrication bearings, characterized in that: It includes a driving device, a rotating shaft, a loading device, a two-phase flow mixer, a test bearing and a two-phase flow sampling and separation device; The driving device is connected to the rotating shaft to drive the rotating shaft, the test bearing is mounted on the rotating shaft, and the loading device is mounted on the test bearing to load a radial load on the test bearing; The two-phase flow mixer comprises a mixer body, a compressed air source and an oil pump, an air inlet and an oil inlet are arranged at one end of the mixer body, and a two-phase flow outlet is arranged at the other end, the compressed air source is connected to the air inlet through an air inlet pipe, the oil pump is connected to the oil inlet through an oil inlet pipe, and flow detection devices are arranged on the air inlet pipe and the oil inlet pipe, at least two cavities are arranged in sequence in the mixer body along the flow direction of the oil-gas two-phase flow, and at least one partition with a plurality of through holes is arranged in each of the cavities, and two adjacent cavities are connected through a narrow channel, and the two-phase flow outlet is connected to the test bearing; The test bearing includes multiple bearing shells, and an oil hole is opened at the entrance of the bearing shell. The two-phase flow sampling and separation device is connected to the oil hole through a sampling tube, and a stop valve is provided on the sampling tube. The two-phase flow sampling and separation device is used to sample the oil-gas two-phase flow from the oil hole and perform oil-gas separation on the sampled oil-gas two-phase flow.

2. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The two-phase flow sampling and separation device comprises a container, a two-phase flow pipeline and a test tube; The container contains water, the test tube is inverted in the container and filled with water, the outlet end of the two-phase flow pipeline extends from the container into the test tube, and the inlet end of the two-phase flow pipeline is connected to the sampling tube.

3. The tilting pad directional lubrication bearing two-phase flow test system according to claim 2, characterized in that: The test tube is provided with a scale.

4. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The driving device comprises a driving motor and a gear box, the driving motor is connected to the gear box via a coupling, and the gear box is connected to the rotating shaft via a coupling.

5. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The system further comprises a support bearing for supporting the rotating shaft.

6. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The mixer body is made of metal or glass.

7. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The partition is made of stainless steel.

8. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The through holes on the partition have a diameter of 2.5 to 3.5 mm.

9. The tilting pad directional lubrication bearing two-phase flow test system according to claim 1, characterized in that: The bearing bush is provided with a front groove.

10. A two-phase flow test method for tilting pad directional lubrication bearings, characterized in that: Based on the system according to any one of claims 1 to 9, the method comprises the following steps: Step S1, turning on the compressed gas source and the oil pump to quantitatively deliver an oil-gas two-phase flow to the test bearing according to a preset first gas volume fraction through the flow detection device and the mixer body; Step S2, turning on the driving device and the loading device, wherein the driving device drives the test bearing to rotate via the rotating shaft, and the loading device loads a radial load to the test bearing; Step S3, obtaining the relationship between the first gas volume fraction and various bearing performance parameters under different loads and rotation speeds, wherein the various bearing performance parameters include the oil film pressure, oil film thickness, bearing surface temperature, fluid state and friction power consumption of the bearing; Step S4, opening the stop valve to sample the oil-gas two-phase flow on the test bearing using the two-phase flow sampling and separation device and obtaining the second gas volume fraction of the sampled oil-gas two-phase flow; Step S5, adjusting the first gas volume fraction according to the relationship between the first gas volume fraction and various bearing performance parameters and the second gas volume fraction.

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