Rotating machinery shaft end fluid pressure adjusting device

Abstract

A rotary mechanical shaft end fluid pressure adjusting device comprises a circular ring and axial flow guide grooves, the axial flow guide grooves are evenly distributed in the inner surface of the circular ring in the circumferential direction, the groove shapes are logarithmic spiral lines or parabolas or involutes, and the number of the axial flow guide grooves is 30-120. The circular ring is used for being fixed to the inner surface of the stator, and a radial gap is formed between the circular ring and the rotor. According to the invention, the pressure of the flowing fluid at the shaft end can be reduced or increased in the axial direction, the adjusted pressure can further meet the performance requirements of subsequent sealing or other parts, and the function completeness and stability of the whole machine are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of rotating components, and particularly relates to a fluid pressure regulating device at the shaft end of a rotating machine, which can be used in equipment such as high-speed aero-engines, steam turbines, high-speed oil pumps, compressors, blowers, etc. Background Art

[0002] Rotating machinery is a mechanical device that transfers energy or moves substances through rotation, and its main components usually include rotors, bearings, machine bases, gears, etc. Rotating machinery is widely used in industrial sectors such as power, aerospace, metallurgy, and petrochemical industries. Common rotating machinery includes steam turbines, centrifugal compressors, generators, water pumps, fans, electric motors, etc. Generally, fluids involved in energy conversion, lubrication, and sealing are filled inside rotating machinery. Due to the often large pressure difference formed between the inside of rotating machinery and the environment, the fluid is prone to axial or radial leakage, which has a serious impact on the design of subsequent functional components, the environment, or society. For example, once a large pressure difference appears, it will directly seriously affect the design of subsequent sealing components. Furthermore, once there is no sealing unit that meets the performance requirements, it is very likely to lead to the realization of the functions of the entire machine system, and in severe cases, it will cause great harm to the environment or society. With the development of rotating machinery equipment or systems in various engineering fields towards high speed, high pressure, and high reliability, the change in the fluid pressure distribution at the shaft end is of great value for subsequent sealing design or other unit development, and will also play an important role in promoting the stable and safe operation of the entire machine.

[0003] Currently, many patents have described devices and equipment for changing the fluid flow field at the shaft end of rotating machinery. For example, the patent named "A Centrifugal Pump Seal Ring with Axial Flow Channels" (Publication No. CN108869379A) discloses a centrifugal pump seal ring with axial flow channels installed between the volute and the impeller. The seal ring consists of a circular ring and axial flow channels. A plurality of axial flow channels are evenly arranged along the circumferential direction on the inner side wall of the circular ring. The presence of the guide vanes causes the rotating liquid to generate a directional flow, and the flow direction is opposite to the movement direction of the leaking fluid, thereby achieving the purpose of reducing the circumferential leakage of the fluid. This invention focuses on the guiding effect of the fluid. The fluid channels formed between the guide plates are relatively large in the radial direction and cannot form a converging gap, and thus cannot effectively utilize the dynamic pressure effect of the fluid, and the ability to regulate the pressure of the fluid at the shaft end is limited.

[0004] The patent with the title "A novel tooth seal structure capable of enhancing the sealing performance" (publication number CN112112976A) presents a novel tooth seal structure capable of enhancing the sealing performance. In this novel tooth seal structure, spiral teeth are directly arranged on the rotor component or stator component of a rotating machine. By setting the helix direction of the spiral groove, the fluid is made to flow in a directional manner, and the directional flow direction is opposite to the leakage direction, so as to achieve the purpose of reducing the leakage amount. This patent takes into account the pumping effect generated by the spiral groove and arranges baffles in the spiral groove to guide the fluid flow direction. However, the depth of the spiral groove opened in this patent is relatively deep. When the fluid flows in the spiral groove, the hydrodynamic pressure effect is not significant. At the same time, the cross-sectional area of the spiral groove opened in the flow direction is the same as the groove width, and no convergent or divergent region is formed, which further reduces the role of the hydrodynamic pressure effect.

[0005] The labyrinth seal introduced in the patent with publication number CN113606344A, which optimizes the rotor dynamic characteristics based on anti-rotation plates between teeth, is a labyrinth seal that optimizes the rotor dynamic characteristics based on anti-rotation plates. This seal consists of a seal stator and a seal rotor, and several groups of anti-rotation plates are circumferentially arranged between the seal teeth on the seal stator. The presence of the anti-rotation plates weakens the circumferential swirl inside the labyrinth seal chamber and reduces the cross stiffness, thereby achieving the purpose of enhancing the sealing stability. This invention focuses on guiding the airflow passing through the anti-rotation plate structure in the reverse rotation direction to increase the sealing stability, but does not consider using the diversion to change the pressure distribution of the flow field to reduce the fluid mass flow rate and thus reduce the leakage.

[0006] The patent with publication number WO2016140056A1 presents a sealing ring installed in an annular groove provided on the outer circumference of a shaft, which can reduce the rotational torque and is not affected by the eccentricity of the shaft relative to the housing. This sealing ring is used to seal the annular gap between the shaft and the housing. It is characterized in that two hydrodynamic pressure generating grooves are opened on the outer peripheral surface of the sealing ring. By opening the two hydrodynamic pressure grooves, the force-bearing area of the fluid pressure received by the sealing ring is reduced, and at the same time, the generation of hydrodynamic pressure is promoted to make the sealing ring away from the shaft hole, thereby reducing the rotational torque. This invention realizes enhancing the pressure of the fluid in the sealing area by constructing the hydrodynamic pressure generating grooves, but lacks the guidance of the fluid rotation direction and flow direction. Since it is a sealing structure and focuses on reducing the leakage of the sealing fluid, it also lacks the structural design to promote the fluid pressure drop. At the same time, the sealing ring described in this patent is installed on a rotating shaft provided with an annular groove, but the fluid leakage between the sealing ring and the rotating shaft is not considered.

[0007] Except for the sealing structure, Patent Publication No. US6318896B1 introduces an annular fluid film bearing formed by a stator ring and a rotatable element concentrically installed within the stator ring, and describes a diffuser and an inlet guide vane adjacent to the inlet end of the annular bearing gap. The diffuser enhances the static pressure of the fluid before it enters the annular gap, and the guide vane gives the fluid a tangential velocity opposite to the rotation direction of the rotatable element, thereby providing radial support for the rotatable element and stiffness and damping for the bearing. This invention focuses on changing the fluid flow direction through the guide vane and enhancing the static pressure effect of the fluid through the diffuser to change the axial fluid pressure. The guide vane and diffuser described in this invention result in a relatively large total pressure loss of the fluid flowing into the gap and a significant reduction in the reverse tangential flow velocity of the fluid, which is not conducive to reducing the axial swirl within the sealing gap. The fluid flow velocity and pressure loss can be further reduced by constructing a converging gap.

[0008] In summary, current research results on changing the pressure distribution and flow characteristics of the fluid flow field at the shaft end of rotating machinery along the axial direction mainly focus on setting anti-rotation plates and developing new-structured labyrinth seals, etc. The common drawback is that the fluid flow channels formed by the guide structures or guide grooves proposed in the form of anti-rotation plates are too deep to meet the formation conditions of the fluid dynamic pressure effect, that is, the fluid flow channels formed by the guide plates or guide grooves do not form a converging or diverging region, and the effective utilization of the dynamic pressure effect is insufficient; while the labyrinth seal focuses on forming a local high-pressure region for sealing, but lacks a structure to promote fluid pressure drop, resulting in the seal being unable to withstand large pressure drops before and after. Therefore, in view of the deficiencies in the above research and to adapt to the increasingly complex shaft end working conditions of rotating machinery, it is necessary to develop devices or components that can effectively regulate the pressure distribution of the fluid flow field at the shaft end of rotating machinery. Summary of the Invention

[0009] To overcome the shortcomings of the above prior art, the purpose of the present invention is to provide a fluid pressure regulating device for the shaft end of a rotating machinery, which can realize the regulation of pressure reduction or increase of the flowing fluid at the shaft end along the axial direction. The regulated pressure can further meet the performance requirements of subsequent seals or other components, ensuring the integrity and stability of the overall machine's functions.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is:

[0011] A fluid pressure regulating device for the shaft end of a rotating machinery, comprising a circular ring and axial guide grooves. The axial guide grooves are evenly distributed circumferentially on the inner surface of the circular ring. The circular ring is used to be fixed on the inner surface of the stator and has a radial gap with the rotor.

[0012] By constructing the shape of the fluid gap, guiding the fluid flow direction, or utilizing the hydrodynamic pressure effect to change the axial pressure distribution of the flow field, the present invention can be directly used as a radial seal to reduce leakage, or can be installed in front of the axial seal to reduce the axial seal inlet pressure and improve the axial seal performance; moreover, the structure of this device is simple, easy to process, and has high reliability.

[0013] In one embodiment, the ring, the axial guide groove, and the rotating shaft are coaxial. A clearance fit is adopted between the ring and the rotating shaft, and the fit range is 0.1-1‰ of the rotor diameter.

[0014] In one embodiment, the inner wall radius R of the ring = (D / 2) + [(0.1-1)D / 1000], that is, there is a radial clearance of (0.1-1)D / 1000 between the inner side wall of the ring and the rotor surface, where D is the diameter of the rotor. The axial length L of the ring = (0.06-0.1)R, and the radial thickness e of the ring = (0.01-0.02)R; the depth h of the axial guide groove in the radial direction does not exceed 0.6-0.9 times the radial thickness e of the ring to ensure the structural strength.

[0015] In one embodiment, the axial guide grooves are uniformly formed on the inner surface of the ring, and the number is 30-120, so as to guide the fluid at the shaft end to generate a directional flow or form a hydrodynamic pressure effect to adjust the axial pressure distribution of the fluid at the shaft end.

[0016] In one embodiment, the depth of the axial guide groove is in the micron level, forming a micron-level shallow groove convergent wedge-shaped region that meets the formation conditions of the hydrodynamic pressure effect. When the fluid at the shaft end has a certain rotational speed as the rotor rotates, the fluid at the shaft end is brought into the convergent wedge-shaped gap between the shaft and the pressure regulating device to form a hydrodynamic pressure effect, forming a local high-fluid pressure region.

[0017] In one embodiment, the depth of the axial guide groove is 2-15 μm.

[0018] In one embodiment, the depth of the axial guide groove is in the millimeter level, which plays a guiding role for the fluid at the shaft end; when the rotation direction of the rotor is the same as the helix direction of the groove, it promotes the fluid to flow in the axial direction; when the rotor direction is opposite to the groove direction, it inhibits the fluid from flowing in the axial direction; by promoting or inhibiting the axial flow of the fluid, the pressure distribution of the fluid flow field at the shaft end is changed.

[0019] In one embodiment, the depth of the axial guide groove is 0.1-10 mm.

[0020] In one embodiment, the groove shape of the axial guide groove is a logarithmic spiral, a parabola, or an involute.

[0021] In one embodiment, when the axial flow guiding groove adopts a logarithmic spiral, the polar coordinate equation of the logarithmic spiral is r = r0exp(θcotβ), where r is the polar radius; r0 is the starting polar radius; β is the spiral angle; θ is the circumferential angle between the logarithmic spiral at the polar radius and the starting point; points are evenly taken on the circumference with a radius of L as the starting points of the logarithmic spiral and multiple logarithmic spirals are drawn, and L is used to intercept two adjacent spirals as the groove profile definition line of the axial flow guiding groove;

[0022] When the axial flow guiding groove adopts a parabola, the parametric form of the parabola is where t is the circumferential angle between the parabola at the polar radius and the starting point, p is the focal parameter, and the starting radius is the axial length L of the ring; points are evenly taken on the circumference with a radius of L as the starting points of the parabola and multiple parabolas are drawn, and L is used to intercept two adjacent parabolas as the groove profile definition line of the axial flow guiding groove;

[0023] When the axial flow guiding groove adopts an involute, the polar coordinate equation of the involute is θ k is the involute angle of development, r k is the radius vector on the involute, α k is the pressure angle on the involute; points are evenly taken on the circumference with a radius of L as the starting points of the involute and multiple involutes are drawn, and L is used to intercept two adjacent involutes as the groove profile definition line of the axial flow guiding groove.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention can be installed at the end of the rotating machine shaft. When the rotor rotates to drive the fluid to rotate and flow, due to the shape characteristics of the provided flow guiding groove or the formed divergent (convergent) region, the fluid flow direction is guided, and the dynamic pressure effect of the fluid flow is obvious, which can effectively change the fluid flow state, and then change the pressure distribution and flow characteristics of the flow field to achieve the function of fluid pressure regulation.

[0026] 2. The present invention can adapt to different pressure regulation requirements by setting different flow guiding structure shapes, quantities, and rotation directions. The spatial conditions of the clearance regions formed by the flow guiding structures with different shapes, quantities, and rotation directions are different, which in turn affect the dynamic pressure effect generated when the fluid flows through the clearance and the degree of being guided by the flow guiding structure. By reasonably setting the flow guiding structure, the fluid pressure can be effectively regulated.

[0027] 3. The present invention has a wide range of uses. It can directly act as a radial seal to prevent axial leakage, or can be arranged before the axial seal to regulate the fluid pressure, which helps to improve the sealing performance of the axial seal. Brief Description of the Drawings

[0028] Figure 1Schematic structural diagram of the present invention with deep axial diversion grooves opened.

[0029] Figure 2 Schematic installation diagram for the implementation of the present invention.

[0030] Figure 3 is Figure 1 Schematic diagram of the ring structure in

[0031] Figure 4 Structural diagram of the present invention with shallow axial diversion grooves opened. Specific implementation mode

[0032] The implementation mode of the present invention will be described in detail below in conjunction with the drawings and embodiments.

[0033] The present invention relates to a fluid pressure regulating device for the shaft end of a rotating machine. By opening axial diversion grooves to guide the fluid flow direction, or by constructing convergent or divergent gaps to form or enhance the fluid dynamic pressure effect, the flow field distribution is changed, and the pressure regulation of the fluid at the shaft end of the rotating machine is realized.

[0034] As Figure 1 shown, the present invention mainly consists of a ring 1 and axial diversion grooves 2. There are multiple axial diversion grooves 2, which are evenly distributed on the inner surface of the ring 1 along the circumferential direction. Obviously, the central axis of the distribution of all the axial diversion grooves 2 is preferably collinear with the central axis of the ring 1. In the present invention, the axial diversion grooves 2 penetrate the inner surface of the ring 1. Here, the axial direction is a general concept, not the straight axial direction of a narrow mechanical shaft, but any direction that can penetrate both ends of the inner surface of the ring 1.

[0035] As Figure 2 shown, the implementation mode of the present invention is to coaxially install the ring 1 and the axial diversion grooves 2 with the rotor 3. The ring 1 and the axial diversion grooves 2 are fixed as a whole on the stator of the rotating machine and are coaxial with the rotating shaft. Preferably, an interference fit can be adopted between the ring 1 and the stator, and a clearance fit can be adopted between the ring 1 and the rotating shaft. The specific cooperation range can be set to 0.1 - 1‰ of the rotor diameter. There is a radial clearance between the inner surface of the ring 1 and the rotor 3, and the clearance size is obtained according to the diameter D of the rotor 3, and the value range is (0.1 - 1)D / 1000.

[0036] The number of the axial diversion grooves 2 of the present invention is preferably 30 - 120, so as to guide the fluid at the shaft end to generate a directional flow or form a dynamic pressure effect to regulate the axial pressure distribution of the fluid at the shaft end.

[0037] As Figure 3As shown, the dimensional parameters of the circular ring 1 in the present invention include its inner wall radius R, radial thickness e, and axial length L. Among them, the inner wall radius R is determined by the diameter D of the rotor 3, and numerically it is (D / 2) + [(0.1 - 1)D / 1000]; the radial thickness e is 0.01 - 0.02 times the radius R; the axial length L is 0.06 - 0.1 times the radius R.

[0038] As Figure 4 shown, the outer shape of the axial flow guide groove can be defined by a logarithmic spiral, or can be defined by a parabola, an involute, etc. The value of the depth h of the axial flow guide groove 2 in the radial direction does not exceed 0.6 - 0.9 times the aforementioned radial thickness e to ensure the structural strength of the circular ring 1.

[0039] Referring again to Figure 1 , the groove depth (i.e., the depth h in the radial direction) of the axial flow guide groove 2 is in the millimeter range, with a range of 0.1 - 10 mm (specifically calculated based on the hydrostatic throttling equation). At this time, the axial flow guide groove 2 is a deep groove structure. Compared with the micron-level shallow groove structure, the hydrodynamic effect of the millimeter-level deep groove is weak; due to the pumping effect, it guides the fluid at the shaft end. When the rotation direction of the rotor is the same as the helical direction of the groove opening, it promotes the fluid to flow along the axial direction; when the rotor direction is opposite to the groove opening direction, it inhibits the fluid from flowing along the axial direction. The promotion or inhibition of the axial fluid flow can change the flow field characteristics of the fluid along the axial direction, and further change the pressure distribution of the fluid flow field at the shaft end.

[0040] Referring again to Figure 4 , the groove depth (i.e., the depth h in the radial direction) of the axial flow guide groove 2 is in the micron range, distributed on the inner surface of the circular ring 1 to form a micron-level shallow groove converging wedge-shaped region, and this wedge-shaped region can meet the formation conditions of the hydrodynamic effect. The design range of its groove depth is preferably 2 - 15 μm (specifically calculated based on the hydrodynamic lubrication control equation). At this time, the axial flow guide groove 2 is a shallow groove structure. When the fluid at the shaft end has a certain rotational speed as the rotor rotates, the fluid at the shaft end is brought into the converging wedge-shaped gap between the shaft and the pressure regulating device to form a hydrodynamic effect, and the fluid pressure gradually rises along the direction of the converging gap, and a local high-fluid-pressure area can be formed.

[0041] The following are two specific embodiments of the present invention.

[0042] Embodiment 1

[0043] Aiming at the target of regulating the fluid pressure at the shaft end of a rotating machine with a rotor diameter of 1000 mm, a device for regulating the fluid pressure at the shaft end of a rotating machine is proposed. The following will further describe it in detail with reference to the accompanying drawings.

[0044] Referring to Figure 1, a fluid pressure regulating device at the shaft end of a rotating machine in this embodiment includes a ring 1 and axial flow guiding grooves 2, and the axial flow guiding grooves 2 are uniformly distributed axially on the inner surface of the ring 1.

[0045] Referring to Figure 2 , for the fluid pressure regulating device at the shaft end of a rotating machine in this embodiment, the ring 1 and the axial flow guiding grooves 2 are coaxially installed with the rotor 3, and a gap of 0.6 mm is formed between the inner wall surface of the ring 1 and the rotor 3.

[0046] Referring to Figure 1 , a fluid pressure regulating device at the shaft end of a rotating machine in this embodiment includes a ring 1 and axial flow guiding grooves 2, wherein: the ring 1 is a hollow cylinder, the inner wall radius R of the ring 1 is 500.6 mm, the radial thickness e of the ring 1 is 5.8 mm, and the axial length L of the ring 1 is 34.6 mm; the axial flow guiding grooves 2 are uniformly distributed axially on the inner surface of the ring 1, and the depth h of the guiding flow guiding grooves 2 in the radial direction is 3 mm. At this depth, the hydrodynamic pressure effect is not significant, and the flow guiding grooves play a role in guiding the fluid flow.

[0047] In this embodiment, the groove shape of the axial flow guiding grooves 2 is defined by a logarithmic spiral, and the polar coordinate equation of the logarithmic spiral is r = r0exp(θcotβ), where r is the polar radius; r0 is the starting polar radius; β is the spiral angle; θ is the circumferential angle between the logarithmic spiral at the polar radius and the starting point. If the parametric coordinate form is adopted, the curve can be expressed as The parameter a is equal to the axial length L of the ring, and b is the exponential factor. In this embodiment, the starting polar radius a of the adopted logarithmic spiral is 34.6 mm, and the exponential factor b of the spiral is 0.4 respectively. Under this parameter, the axial flow guiding grooves 2 are uniformly distributed circumferentially on the inner surface of the ring 1. Under the same fluid region and the same boundary conditions, the number of axial flow guiding grooves 2 opened on the ring 1 can enhance the pumping effect. At the same time, the increase in the number of grooves will also bring complexity in processing and affect the quality of the curve. Therefore, through simulation optimization, the number of grooves is selected as 72 in this embodiment.

[0048] The groove shape of the axial flow guiding grooves 2 in this embodiment is spiral. When the fluid flows into the axial flow guiding grooves 2, the fluid is guided by the axial flow guiding grooves 2 to generate a directional flow, promoting or inhibiting the fluid flow in the axial direction, and thus achieving the purpose of regulating the fluid pressure at the shaft end.

[0049] Embodiment 2

[0050] Aiming at the fluid pressure regulation target at the shaft end of a high-speed rotating machine with a rotor diameter of 1000 mm, a fluid pressure regulating device at the shaft end of a rotating machine is proposed. The following will be described in further detail with reference to the accompanying drawings.

[0051] Referring to Figure 4, a fluid pressure regulating device at the shaft end of a rotating machine in this embodiment includes a ring 1 and axial flow guide grooves 2, and the axial flow guide grooves 2 are circumferentially and evenly distributed on the inner surface of the ring 1.

[0052] Refer to Figure 2 , the installation method of this embodiment is the same as that of Embodiment 1, and will not be elaborated here.

[0053] Refer to Figure 4 , a fluid pressure regulating device at the shaft end of a rotating machine in this embodiment includes a ring 1 and axial flow guide grooves 2, where: the ring 1 is a hollow cylinder, the inner wall radius R of the ring 1 is 500.6 mm, the radial thickness e of the ring 1 is 5.8 mm, and the axial length L of the ring 1 is 34.6 mm; the axial flow guide grooves 2 are axially and evenly distributed on the inner surface of the ring 1, and the depth h of the guide flow grooves 2 in the radial direction is 5 μm. At this groove depth, when the fluid flows through the gap area formed by the flow guide grooves, the hydrodynamic pressure effect is significant.

[0054] The groove shape of the axial flow guide grooves 2 in this embodiment is defined by an involute, and the polar coordinate equation of the involute is θ k is the involute angle of the involute, r k is the radius vector on the involute, α k is the pressure angle on the involute; the parametric equation is where θ is the circumferential angle between the involute at the polar radius and the starting point, and r b is the base circle radius, and the value is taken as the axial length L of the ring. In this embodiment, the base circle radius r b of the involute adopted is 34.6 mm. Under this parameter, an obvious convergent gap can be formed between the axial flow guide grooves 2, and due to the groove depth being in the micron level, the hydrodynamic pressure effect of the fluid flowing through the convergent gap is significant. The axial flow guide grooves 2 are circumferentially and evenly distributed on the inner surface of the ring 1, and the number is 72. A convergent gap is formed between the axial flow guide grooves 2. When the fluid flows forward (the fluid channel gradually converges) through the formed convergent gap, due to the hydrodynamic pressure effect, a local fluid high-pressure area is formed between the convergent gaps, which hinders the axial flow of the fluid, and thus changes the fluid pressure distribution at the shaft end. When the fluid flows reversely (the fluid channel gradually diverges) into the convergent gap, the pressure of the fluid rapidly decreases along the flow direction, which is convenient for assembling a sealing device behind the flow pressure regulating device.

Claims

1. A fluid pressure regulating device for the shaft end of a rotating machine, characterized in that, It includes a ring (1) and axial flow guiding grooves (2). The axial flow guiding grooves (2) are evenly distributed circumferentially on the inner surface of the ring (1). The ring (1) is used to be fixed on the inner surface of the stator and has a radial gap with the rotor (3).

2. The fluid pressure regulating device at the shaft end of a rotating machine according to claim 1, characterized in that The ring (1), the axial flow guiding grooves (2) and the rotating shaft are coaxial. A clearance fit is adopted between the ring (1) and the rotating shaft, and the fit range is 0.1 to 1‰ of the diameter of the rotor (3).

3. The fluid pressure regulating device at the shaft end of the rotary machine according to claim 1, wherein The inner wall radius R of the ring (1) = (D / 2) + [(0.1 - 1)D / 1000], that is, there is a radial gap of (0.1 - 1)D / 1000 between the inner side wall of the ring and the surface of the rotor. Where D is the diameter of the rotor (3), the length L of the ring (1) in the axial direction = (0.06 - 0.1)R, and the radial thickness e of the ring (1) = (0.01 - 0.02)R; the depth h of the axial flow guiding grooves (2) in the radial direction does not exceed 0.6 to 0.9 times the radial thickness e of the ring to ensure the structural strength.

4. The fluid pressure regulating device at the shaft end of the rotating machine according to claim 1, characterized in that, The axial flow guiding grooves (2) are evenly formed on the inner surface of the ring (1), and the number is 30 to 120, so as to guide the fluid at the shaft end to generate a directional flow or form a hydrodynamic pressure effect to adjust the pressure distribution of the fluid at the shaft end along the axial direction.

5. The fluid pressure regulating device at the shaft end of the rotating machine according to claim 1, characterized in that, The groove depth of the axial flow guiding grooves (2) is in the micron level, forming a micron-level shallow groove convergent wedge region that meets the formation conditions of the hydrodynamic pressure effect. When the fluid at the shaft end has a certain rotational speed as the rotor (1) rotates, the fluid at the shaft end is brought into the convergent wedge gap between the shaft and the pressure regulating device to form a hydrodynamic pressure effect, forming a local high fluid pressure area.

6. The fluid pressure regulating device at the shaft end of a rotating machine according to claim 5, characterized in that The groove depth of the axial flow guiding grooves (2) is 2 to 15 μm.

7. The fluid pressure regulating device for the shaft end of a rotating machine according to claim 1, wherein The groove depth of the axial flow guiding grooves (2) is in the millimeter level, which plays a role in guiding the fluid at the shaft end; when the rotation direction of the rotor (3) is the same as the helix direction of the grooves, it promotes the fluid to flow along the axial direction; when the direction of the rotor (3) is opposite to the groove direction, it inhibits the fluid from flowing along the axial direction; by promoting or inhibiting the axial flow of the fluid, the pressure distribution of the fluid flow field at the shaft end is changed.

8. The fluid pressure regulating device at the shaft end of the rotating machine according to claim 5, characterized in that, The groove depth of the axial flow guiding grooves (2) is 0.1 to 10 mm.

9. The fluid pressure regulating device at the shaft end of the rotary machine according to claim 1, characterized in that The groove shape of the axial flow guiding grooves (2) is a logarithmic spiral, a parabola or an involute.

10. The fluid pressure regulating device for the shaft end of a rotating machine according to claim 9, wherein When the axial flow guiding grooves (2) adopt a logarithmic spiral, the polar coordinate equation of the logarithmic spiral is r = r0exp(θcotβ), where r is the polar radius; r0 is the starting polar radius; β is the spiral angle; θ is the circumferential angle between the logarithmic spiral at the polar radius and the starting point; points are evenly taken on the circumference with a radius of L as the starting points of the logarithmic spiral and multiple logarithmic spirals are drawn, and L is used to intercept the adjacent two spirals as the groove type definition line of the axial flow guiding grooves (2); When the axial diversion groove (2) adopts a parabola, the parametric form of the parabola is where t is the circumferential angle between the parabola at the polar radius and the starting point, p is the focal parameter, and the starting radius is the axial length L of the ring (1); points are evenly taken on the circumference with a radius of L as the starting points of the parabolas, and multiple parabolas are drawn. The adjacent two parabolas are intercepted by L to serve as the groove profile defining lines of the axial diversion groove (2). When the axial flow guiding groove (2) adopts an involute, the polar coordinate equation of the involute is θ k is the involute expansion angle, r k is the radius vector on the involute, α k is the pressure angle on the involute; points are evenly taken on the circumference with a radius of L as the starting points of the involute, and multiple involutes are drawn. The distance between adjacent involutes intercepted by L is used as the groove profile definition line of the axial flow guiding groove (2).

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