CN114060108A - Water-lubricated bearing of turbine type energy recovery all-in-one machine - Google Patents
Water-lubricated bearing of turbine type energy recovery all-in-one machine Download PDFInfo
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- CN114060108A CN114060108A CN202111264483.2A CN202111264483A CN114060108A CN 114060108 A CN114060108 A CN 114060108A CN 202111264483 A CN202111264483 A CN 202111264483A CN 114060108 A CN114060108 A CN 114060108A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/16—Arrangement of bearings; Supporting or mounting bearings in casings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/18—Lubricating arrangements
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- General Engineering & Computer Science (AREA)
- Sliding-Contact Bearings (AREA)
Abstract
The invention discloses a water-lubricated bearing of a turbine type energy recovery all-in-one machine, wherein 4-12 grooves are uniformly distributed on the inner surface of the bearing, and the grooves are through grooves and are communicated with a pump end and a turbine end; the molded line of the groove is a lower convex parabolic segment, a first inclined straight segment, a second inclined straight segment and an upper convex parabolic segment which are connected end to end from the pump end to the turbine end in sequence; the first inclined straight line section and the second inclined straight line section are positioned in the middle section of the bearing in the axial direction and are both straight line sections inclined at 45 degrees; one ends of the first inclined straight line section and the second inclined straight line section are connected to form an included angle, and the opening direction of the included angle faces to the rotating direction of the bearing. The inner wall surface of the bearing is in clearance fit with the main shaft, and a water film between the bearing and the main shaft is used as a lubricating medium; the circumferential positions of the two ends of the groove are different, dynamic pressure is generated to resist the pressure difference of the two ends when the rotor rotates, and the water film is driven to flow back from the lower turbine end to the higher pump end, so that the effect of reducing leakage amount is achieved.
Description
Technical Field
The invention relates to a water-lubricated bearing, in particular to a groove type water-lubricated bearing suitable for a turbine type energy recovery all-in-one machine.
Background
The turbine type energy recovery all-in-one machine is an important device for recovering pressure energy in high-pressure strong brine, reducing system energy consumption and guaranteeing economy in a reverse osmosis seawater desalination system, and can be widely applied to small and medium reverse osmosis seawater desalination systems. Through the coaxial integrated design of a booster pump and an energy recovery turbine, the turbine is utilized to recover the pressure energy in the high-pressure strong brine intercepted by the reverse osmosis membrane, and the impeller of the drive pump is used for boosting the fresh seawater, so that the energy recovery is realized.
The rotor is a core component of the turbine type energy recovery all-in-one machine, consists of a turbine impeller, a main shaft and a pump impeller, and is supported by a water lubrication bearing. The water lubricated bearing of the all-in-one machine takes water conveyed by the bearing as a lubricating medium, so that frictional wear can be obviously reduced, high-frequency vibration is improved, the pollution of the conveyed water by lubricating oil is avoided, the energy recovery efficiency is improved, and the service life of equipment is prolonged.
The working environment of the water lubricating bearing of the all-in-one machine has the following characteristics: (1) the rotating speed is high, and generally can reach thousands of turns to tens of thousands of turns; (2) the pressure is high, and the working pressure is up to more than 5 MPa; (3) the pressure difference exists at the two ends of the bearing, the bearing gap is communicated with the pump cavity and the turbine cavity, the pressure at the pump end is often higher than that at the turbine end, and the pressure difference can reach 0.1MPa at most. Characteristics (1) and (2) put forward higher requirements for rotor stability, and characteristic (3) has decided that the traditional stability-improving groove and tilting pad structure is difficult to be applied, otherwise, leakage amount can be seriously increased, and the original seawater at the pump end directly leaks to the turbine cavity from the bearing gap, which affects the efficiency of the seawater desalination system. Therefore, how to take stability and dynamic sealing into consideration is an important problem in the design of the water lubrication bearing of the all-in-one machine.
Disclosure of Invention
Based on the prior art, the invention provides the water-lubricated bearing of the turbine type energy recovery all-in-one machine, which overcomes the influence of high-pressure water environment, can ensure the stable operation of a rotor at high rotating speed, and can obviously reduce the leakage.
The present invention achieves the above-described object by the following technical means.
The water lubrication bearing of the turbine type energy recovery all-in-one machine is characterized in that 4-12 grooves are uniformly distributed on the inner surface of the bearing, and the grooves are through grooves and communicate a pump end with a turbine end; the molded line of the groove is a parabolic line section with an upward opening, a first inclined straight line section, a second inclined straight line section and a parabolic line section with a downward opening which are connected end to end in sequence from the pump end to the turbine end; the first inclined straight line section and the second inclined straight line section are positioned in the middle section of the bearing in the axial direction and are both straight line sections inclined at 45 degrees; one ends of the first inclined straight line section and the second inclined straight line section are connected to form an included angle, and the opening direction of the included angle faces to the rotating direction of the bearing.
Furthermore, the included angle of the first inclined straight line section and the second inclined straight line section is a right angle; the connection positions of the parabolic line segment with the upward opening and the first inclined straight line segment and the connection positions of the second inclined straight line segment and the parabolic line segment with the downward opening are in tangent relation.
Further, expanding the inner surface of the bearing along the circumferential direction, and taking the vertex of the connection of the first inclined straight line section and the second inclined straight line section of the groove profile as an origin O; the axial direction of the bearing is taken as the y axis, and the direction of the pump end is taken as the positive direction; the circumferential direction is an x axis and the rotation direction of the rotor is a positive direction; x is equal to R θ, where R is the inner diameter of the bearing, and θ is the circumferential angle corresponding to the distance x from the origin O toward the rotation direction of the rotor; the expression for the trench profile is:
wherein, L is the width of the bearing, a is a variable parameter, and the value range is more than 0 and less than 0.6.
Further, the value of a is related to the pressure difference at two ends of the bearing and the dynamic sealing performance requirement, the larger the pressure difference at two ends of the bearing is, the higher the dynamic sealing performance requirement is, and the larger the optimal value of a is; determining the value of a by the following formula:
a＝0.6-0.6×e-kp
the parameter k is 1.178 x 10-7Pa-1And p is the pressure difference between the two ends of the bearing under the rated working condition.
Further, the reserved gap between the bearing and the shaft is 0.05-0.1 mm.
Furthermore, the cross section of the groove is rectangular, and the depth of the groove is 4 times of the reserved gap between the bearing and the shaft.
Further, the width b of the trenchgDetermined by the following formula:
wherein n is the number of grooves, KgFor variable parameters, generally take Kg＝0.8～1。
Further, the surface roughness of the ridge region 2 between the grooves is less than ra0.8.
Furthermore, the bearing material is TC4 titanium alloy, and the thickness is 10-20 mm.
The water-lubricated bearing for the turbine type energy recovery all-in-one machine improves the shape of a groove on the inner surface of the bearing, introduces a variable parameter a into the curve of a groove profile, and determines the value of the variable parameter a according to the pressure difference at two ends of the bearing and the dynamic sealing performance requirement. Introducing variable parameter K into groove width determination formulagDetermining the variable parameter K according to the requirement for tightnessgThe value of (a). The bearing clearance is determined based on the rotating speed and the sealing performance, and is taken at a value of 0.05-0.1 mm; the higher the rotating speed, the lower the sealing requirement and the larger the optimal value of the radius clearance. Therefore, the working environment with large pressure difference at two ends of the main shaft bearing of the turbine type energy recovery all-in-one machine can be effectively aimed at, the dynamic sealing performance is improved while the stability of the high-speed rotor is guaranteed, the leakage generated by the pressure difference is remarkably reduced, and the stable and efficient operation of the all-in-one machine is guaranteed.
Drawings
FIG. 1 is a schematic view of a water lubricated bearing according to the present invention;
FIG. 2 is an expanded view of the water lubricated bearing groove structure provided by the present invention;
FIG. 3 is a schematic view of a groove profile design for a water lubricated bearing provided by the present invention;
FIG. 4 is a water film pressure distribution cloud chart of the water lubricated bearing provided by the invention;
FIG. 5 is a graph comparing the performance of a water lubricated bearing provided by the present invention with a non-grooved bearing, 45 degree herringbone groove bearing.
In the figure:
1-groove, 2-land.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.
As shown in figure 1, the water-lubricated bearing of the turbine type energy recovery all-in-one machine is made of TC4 titanium alloy, the inner diameter and the width are determined by a main shaft, and the thickness is 10-20 mm. The inner wall surface of the bearing is in clearance fit with the main shaft, a water film between the bearing and the main shaft is used as a lubricating medium, bearing capacity is formed by means of the hydrodynamic lubrication effect of the water film, and a special groove structure is arranged on the inner surface of the bearing. The number of the grooves on the inner surface of the bearing is 4-12, and the grooves are uniformly distributed. The groove is a through groove and is communicated with the pump end and the turbine end; the molded line of the groove is a parabolic line section with an upward opening, a first inclined straight line section, a second inclined straight line section and a parabolic line section with a downward opening which are connected end to end in sequence from the pump end to the turbine end; the first inclined straight line section and the second inclined straight line section are positioned in the middle section of the bearing in the axial direction and are both straight line sections inclined at 45 degrees; one ends of the first inclined straight line section and the second inclined straight line section are connected to form an included angle, and the opening direction of the included angle faces to the rotating direction of the bearing. The included angle of the first inclined straight line section and the second inclined straight line section is a right angle, so that local high pressure is generated at the position, and the bearing performance is improved. The connection positions of the parabolic line section with the upward opening and the first inclined straight line section and the connection positions of the second inclined straight line section and the parabolic line section with the downward opening are in tangent relation, so that the water flow resistance is reduced, and the water guide efficiency is improved. The phase difference of two ends of each groove is formed in the circumferential direction through the two sections of parabolas, and when the all-in-one machine operates, water in the grooves has the tendency of flowing into the pump cavity from the turbine cavity under the action of the acting force of the grooves, so that the dynamic seal is formed by resisting the pressure difference of the two ends.
Expanding the inner surface of the bearing along the circumferential direction, and taking the vertex of the connection of the first inclined straight line section and the second inclined straight line section of the groove profile as an origin O as shown in FIG. 2; the axial direction of the bearing is taken as the y axis, and the direction of the pump end is taken as the positive direction; the circumferential direction is an x axis and the rotation direction of the rotor is a positive direction; then x is R θ, where R is the inner diameter of the bearing and θ is the circumferential angle corresponding to the distance x from the origin O toward the direction of rotation of the rotor.
As shown in fig. 3, the length of the parabola segment with the upward opening in the axial direction of the bearing is L/3; the length of the first inclined straight line section in the axial direction is L/6; the length of the second inclined straight line section in the axial direction is L/3; the length of the parabolic line segment with the downward opening in the axial direction is L/6. The expression for the trench profile is then:
wherein, L is the width of the bearing, a is a variable parameter, and the value range is more than 0 and less than 0.6. Specifically, the value of a is related to the pressure difference and the dynamic sealing performance requirements at two ends of the bearing, and the larger the pressure difference at two ends of the bearing is, the higher the dynamic sealing performance requirement is, and the larger the optimal value of a is; determining the value of a by the following formula:
a＝0.6-0.6×e-kp
the parameter k is 1.178 x 10-7Pa-1And p is the pressure difference between the two ends of the bearing under the rated working condition. For the condition of 50kPa pressure difference across the bearing, a may be 0.267, and one profile coordinate of this condition is shown in table 1.
TABLE 1
| y/mm | 0.00 | 2.00 | 4.00 | 6.00 | 8.00 | 10.00 | 12.00 | 14.00 | 16.00 | 18.00 |
| Rθ/mm | -18.33 | -18.29 | -18.09 | -17.74 | -17.21 | -16.52 | -15.64 | -14.57 | -13.29 | -11.78 |
| y/mm | 20.00 | 22.00 | 24.00 | 26.00 | 28.00 | 30.00 | 32.00 | 34.00 | 36.00 | 38.00 |
| Rθ/mm | -10.00 | -8.00 | -6.00 | -4.00 | -2.00 | 0.00 | -2.00 | -4.00 | -6.00 | -8.00 |
| y/mm | 40.00 | 42.00 | 44.00 | 46.00 | 48.00 | 50.00 | 52.00 | 54.00 | 56.00 | 58.00 |
| Rθ/mm | -10.00 | -12.00 | -14.00 | -16.00 | -18.00 | -20.00 | -22.16 | -24.68 | -27.67 | -31.23 |
The reserved clearance between the bearing and the shaft is 0.05-0.1 mm, the higher the rotating speed is, the lower the sealing requirement is, and the larger the optimal value of the reserved clearance is. The cross section of the groove is rectangular, the depth of the groove is 4 times of the reserved gap between the bearing and the shaft, and the groove has the function of guiding the water film to flow. The surface roughness requirement of the land region 2 is ra0.8.
Width b of groovegDetermined by the following formula:
wherein n is the number of grooves, KgFor variable parameters, generally take KgWhen the sealing property is particularly high, K may be selected as 1g＝0.8。
According to the invention, through the groove profile design, the circumferential positions of two ends of the groove are different, and dynamic pressure is generated to resist the pressure difference of the two ends when the rotor rotates, so that a water film is driven to flow back from a turbine end with lower pressure to a pump end with higher pressure, and the effect of reducing the leakage amount is achieved.
As shown in fig. 4, when the pressure difference between both ends of the bearing is 50kPa, the pressure gradient characteristic determined by the pressure difference between both ends can be clearly seen from the water film pressure distribution, but the influence of the groove structure on the pressure distribution can still be seen, and the groove moves the high-pressure region backward in the rotation direction, thereby improving the stability of the rotor.
The bearing of the present invention is compared to conventional herringbone groove bearings, spiral groove bearings and smooth bearings without grooves, as shown in figure 5. Under the condition that other design parameters are not changed, the critical rotating speed of the bearing is only slightly lower than that of a herringbone groove bearing, and is obviously higher than that of a spiral groove bearing and a smooth bearing. Under the working condition that the pressure difference between the two ends is 50kPa, the leakage rate of the bearing is only higher than that of a smooth bearing and is obviously lower than that of a herringbone groove bearing. The bearing has the advantages of both stability and dynamic sealing performance and optimal comprehensive performance.
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.
Claims (9)
1. The water lubrication bearing of the turbine type energy recovery all-in-one machine is characterized in that 4-12 grooves are uniformly distributed on the inner surface of the bearing, and the grooves are through grooves and communicate a pump end with a turbine end; the molded line of the groove is a parabolic line section with an upward opening, a first inclined straight line section, a second inclined straight line section and a parabolic line section with a downward opening which are connected end to end in sequence from the pump end to the turbine end; the first inclined straight line section and the second inclined straight line section are positioned in the middle section of the bearing in the axial direction and are both straight line sections inclined at 45 degrees; one ends of the first inclined straight line section and the second inclined straight line section are connected to form an included angle, and the opening direction of the included angle faces to the rotating direction of the bearing.
2. The turbine-type energy recovery all-in-one water lubricated bearing as recited in claim 1, wherein the included angle of the pair of the first inclined straight line segment and the second inclined straight line segment is a right angle; the connection positions of the parabolic line segment with the upward opening and the first inclined straight line segment and the connection positions of the second inclined straight line segment and the parabolic line segment with the downward opening are in tangent relation.
3. The turbine-type energy recovery all-in-one water-lubricated bearing of claim 1, wherein the inner surface of the bearing is expanded in the circumferential direction, and the vertex at which the first inclined straight line segment and the second inclined straight line segment of the groove profile are connected is taken as an origin O; the axial direction of the bearing is taken as the y axis, and the direction of the pump end is taken as the positive direction; the circumferential direction is an x axis and the rotation direction of the rotor is a positive direction; x is equal to R θ, where R is the inner diameter of the bearing, and θ is the circumferential angle corresponding to the distance x from the origin O toward the rotation direction of the rotor; the expression for the trench profile is:
wherein, L is the bearing width, a is variable parameter, and the value range is 0< a < 0.6.
4. The water-lubricated bearing of the turbine type energy recovery all-in-one machine according to claim 1, wherein the value of a is related to the pressure difference and dynamic sealing performance requirements of two ends of the bearing, and the larger the pressure difference of the two ends of the bearing is, the higher the dynamic sealing performance requirement is, and the larger the optimal value of a is; determining the value of a by the following formula:
a＝0.6-0.6×e-kp
the parameter k is 1.178 x 10-7Pa-1And p is the pressure difference between the two ends of the bearing under the rated working condition.
5. The turbine type energy recovery all-in-one machine water-lubricated bearing as claimed in claim 1, wherein the clearance between the bearing and the shaft is 0.05-0.1 mm.
6. The turbine type energy recovery all-in-one machine water lubricated bearing as claimed in claim 5, wherein the cross section of the groove is rectangular, and the depth is 4 times of the reserved clearance between the bearing and the shaft.
7. The turbine energy recovery all-in-one water lubricated bearing according to claim 3 wherein the width b of the groovegDetermined by the following formula:
wherein n is the number of grooves, KgFor variable parameters, generally take Kg＝0.8～1。
8. The turbine energy recovery all-in-one water lubricated bearing according to claim 1, wherein the surface roughness of the ridge areas (2) between the grooves is less than ra0.8.
9. The turbine type energy recovery all-in-one water-lubricated bearing as claimed in claim 1, wherein the bearing material is TC4 titanium alloy, and the thickness is 10-20 mm.
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| CN202111264483.2A CN114060108A (en) | 2021-10-28 | 2021-10-28 | Water-lubricated bearing of turbine type energy recovery all-in-one machine |
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| CN202111264483.2A CN114060108A (en) | 2021-10-28 | 2021-10-28 | Water-lubricated bearing of turbine type energy recovery all-in-one machine |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115573939A (en) * | 2022-11-14 | 2023-01-06 | 江苏大学 | Self-pressurization type water lubrication bearing of seawater desalination energy recovery all-in-one machine |
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| CN108869377A (en) * | 2018-07-12 | 2018-11-23 | 江苏大学 | A kind of permanent magnetism axial force adaptive equalization device |
| CN110821950A (en) * | 2019-09-23 | 2020-02-21 | 西安交通大学 | Liquid dynamic pressure lubrication herringbone groove bearing with variable groove depth structure |
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| CN112762095A (en) * | 2021-02-26 | 2021-05-07 | 河海大学常州校区 | Water-lubricated radial bearing |
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2021
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202348954U (en) * | 2011-08-29 | 2012-07-25 | 姚文雪 | Hydrodynamic bearing and hydrodynamic rotary shaft with improved structure |
| CN106194989A (en) * | 2016-09-27 | 2016-12-07 | 西安科技大学 | A kind of mixing channel water lubricated rubber bearing peculiar to vessel |
| CN108869377A (en) * | 2018-07-12 | 2018-11-23 | 江苏大学 | A kind of permanent magnetism axial force adaptive equalization device |
| CN110821950A (en) * | 2019-09-23 | 2020-02-21 | 西安交通大学 | Liquid dynamic pressure lubrication herringbone groove bearing with variable groove depth structure |
| CN112580158A (en) * | 2020-11-25 | 2021-03-30 | 东南大学 | Static and dynamic performance design method for high-speed water lubrication dynamic pressure spiral groove radial bearing |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115573939A (en) * | 2022-11-14 | 2023-01-06 | 江苏大学 | Self-pressurization type water lubrication bearing of seawater desalination energy recovery all-in-one machine |
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