Liquid super-slippage step type convergent groove sealing ring

Abstract

The invention discloses a liquid super-slippage step type convergent groove sealing ring which comprises a sealing ring body and is characterized in that a plurality of step type convergent spiral grooves are evenly formed in the inner diameter side of the sealing ring body, an annular area close to the outer diameter side of the sealing ring body is a sealing dam, a sealing weir is formed between every two adjacent spiral grooves, the step type convergent spiral grooves are in a step shape, and the step type convergent spiral grooves are formed in the sealing dam. The bottom of each stepped groove is provided with an ultra-sliding surface, and the step convergent spiral grooves are arranged in the radial direction or the circumferential direction; the sealing performance of the liquid film seal under high-pressure, high-speed and other extreme working conditions is improved, the service life of the liquid film seal can be prolonged, the sealing opening force can be remarkably improved, friction heat is reduced, the cavitation rate is reduced, and the sealing operation stability is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical seals, and in particular relates to a liquid super-slip stepped convergent groove sealing ring. Background Art

[0002] After decades of application and development, liquid film sealing technology has gradually matured and has demonstrated excellent sealing performance in many applications. Liquid film sealing is a form of non-contact mechanical sealing. It uses the characteristics of liquid (such as surface tension, power, pressure, etc.) to form a thin liquid film between the sealing surfaces to achieve a sealing effect. This layer of liquid film can effectively prevent the leakage of gas or liquid, while improving the lubrication state and operability of the sealing end face, making the sealing process more stable and reliable. Liquid film seals can be used for shaft seals, parking seals, spare seals, safety seals, high-speed bearing lubricant seals, etc. for rotary pumps of various media, and are particularly suitable for special working conditions that require zero leakage or zero escape.

[0003] When the local pressure of the liquid film decreases, cavitation will occur. Excessive cavitation will reduce the sealing performance, increase friction, produce cavitation, and change the dynamic characteristics of the liquid film, resulting in unstable sealing performance. Therefore, many scientific researchers are committed to improving the liquid film stiffness or reducing the cavitation of the liquid film by increasing the opening force of the liquid film, so as to achieve the purpose of enhancing the stability of the liquid film.

[0004] Liquid film seal is an important type of mechanical seal. Its main function is to prevent fluid or solid particles from leaking from adjacent mating surfaces and to prevent external impurities such as dust and moisture from invading the interior of the machine. The sealing pair of liquid film seal consists of a dynamic ring, a static ring, and a fluid-type groove designed on the sealing ring. Studies have shown that the fluid-type groove can be opened on the static ring or the dynamic ring, and the sealing effect is almost the same, so the influence of the fluid-type groove on different sealing rings can be ignored. The fluid-type groove can be in the form of a spiral groove, a fan-shaped groove, a Tesla groove, etc.

[0005] The applicant has proposed a groove bottom super-slip modification technology that can be applied to liquid film sealing. It forms a solid-liquid super-slip interface to reduce the adhesion shear force of the fluid on the solid surface, which can reduce the viscous friction between the micro-flow field in the sealing gap and the sealing end face, while increasing the flow velocity of the fluid in the groove area, thereby improving the fluid dynamic pressure effect of the micro-flow field. More importantly, the functional coating on the groove bottom will not suffer any wear or damage due to the operation of the friction pair. In order to better cope with extreme working conditions such as high speed, high pressure, and high temperature, we have conducted more in-depth explorations and recently discovered that by combining the groove bottom texture and the super-slip surface design, a new sealing mechanism can be produced, which significantly improves the comprehensive performance of liquid film sealing. Summary of the invention

[0006] The purpose of the present invention is to design a liquid super-slip step-type convergent groove sealing ring, which has the advantages of greater liquid film stiffness, less friction heat and lower cavitation rate, as well as simple processing and convenient installation.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A liquid super-slip stepped convergent groove sealing ring comprises a sealing ring, characterized in that: a plurality of stepped convergent spiral grooves are evenly arranged on the inner diameter side of the sealing ring, an annular area close to the outer diameter side is a sealing dam, and a sealing weir is formed between adjacent spiral grooves, the stepped convergent spiral grooves are stepped, a super-slip surface is provided at the bottom of each stepped groove, and the stepped convergent spiral grooves are arranged radially or circumferentially.

[0008] Furthermore, the radially stepped convergent spiral groove has a step extension direction that is radial, and a step depth that decreases step by step from the inner diameter side to the outer diameter side, forming a convergent gap.

[0009] Furthermore, the circumferentially stepped convergent spiral groove has a step extension direction that is circumferential, and the step depth decreases or increases step by step along the circumference.

[0010] Furthermore, the stepped convergent spiral groove has three steps, the step depths decrease step by step, and the step depths are 12 μm, 9 μm, and 6 μm respectively, and the end face of the sealing ring is made of cemented carbide or ceramic material.

[0011] Furthermore, the main dimensions of the sealing ring include: outer radius 42.5 mm, inner radius 37.5 mm, ring thickness 9 mm, groove root radius 40 mm, groove width ratio 0.5, groove length ratio 0.5, number of grooves 12, and groove area helix angle 18°.

[0012] Furthermore, there are micro-nanoscale gaps on the surface of the groove bottom, and a superlubricant is arranged in the gaps. The liquid superlubricant is injected into the micro-nanoscale gaps and forms a superslip layer after solidification. The superslip layer allows the liquid medium molecules at the interface between the liquid film and the superslip layer to move freely along the bottom surface of the step-convergent spiral groove. The slip speed of the liquid medium molecules approaches the motion speed of the moving surface, and the slip length of the liquid medium molecules approaches positive infinity, forming a superslip surface at the bottom of the step-convergent spiral groove.

[0013] The following beneficial effects can be obtained through the above technical solution: The present invention improves the sealing performance of liquid film seals under extreme working conditions such as high pressure and high speed, can extend the service life of liquid film seals, can significantly increase the seal opening force, reduce frictional heat, reduce cavitation rate, and further improve the sealing operation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a super-slip radial step-type convergent spiral groove sealing ring.

[0015] Figure 2 It is a schematic diagram of a super-slip circumferential step-convergent spiral groove sealing ring.

[0016] Figure 3 It is a schematic diagram of the working process of the super-slip step-type convergent trough.

[0017] Figure 4 It is a schematic diagram of the direction of liquid film rotation.

[0018] Figure 5 This is a schematic diagram comparing the velocity vectors of the super-slip radial step-convergent spiral groove with the circumferential step-convergent spiral groove at the groove bottom.

[0019] Figure 6 It is a comparison diagram of the velocity vectors of the groove section parallel to the groove bottom of the super-slip radial step-type convergent spiral groove relative to the circumferential step-type convergent spiral groove.

[0020] Figure 7 It is a comparison diagram of the velocity vectors of the super-slip circumferential step-convergent spiral groove and the circumferential step-convergent spiral groove at the groove bottom.

[0021] Figure 8 This is a comparison diagram of the cavitation distribution of the super-slip circumferential step-convergent spiral groove versus the circumferential step-convergent spiral groove.

[0022] Fig. 9 These are two types of groove bottom surface structure diagrams. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 1-8 As shown, a liquid super-slip step-type convergent groove sealing ring includes a sealing ring, characterized in that: a plurality of step-type convergent spiral grooves 1 are evenly arranged on the inner diameter side of the sealing ring, the annular area close to the outer diameter side is a sealing dam 2, and a sealing weir 3 is formed between adjacent spiral grooves. The step-type convergent spiral groove is stepped, and each step plane is provided with a super-slip surface 4. The step-type convergent spiral groove is arranged radially or circumferentially. The super-slip surface structure is as follows: the surface of the bottom of the groove has micro-nanoscale voids, and a super-lubricant 5 is arranged in the voids. The liquid super-lubricant is injected into the micro-nanoscale voids, and a super-slip layer is formed after solidification. The super-slip layer allows the liquid medium molecules at the interface of the liquid film and the super-slip layer to move freely along the bottom surface of the step-type convergent spiral groove, and the slip velocity of the liquid medium molecules approaches the motion velocity of the moving surface, and the slip length of the liquid medium molecules approaches positive infinity. A super-slip surface is formed at the bottom of the step-type convergent spiral groove. Wherein Fig. 9 As shown, the surface of the groove bottom is a porous structure 6 or a rough body 7, and the protrusions in the rough body 7 can be in a triangle, arc or other shape.

[0024] The setting method of the stepped convergent spiral groove is specifically to distinguish radial or circumferential according to the step extension direction, wherein the radial step-type convergent groove extends in the radial direction, and the circumferential step-type convergent groove extends in the circumferential direction. It is divided into 3 steps, and the step depth decreases step by step. The main dimensions of the sealing ring include: outer radius 42.5mm, inner radius 37.5mm, ring thickness 9mm, groove root radius 40mm, groove width ratio 0.5, groove length ratio 0.5, number of grooves 12, groove area helix angle 18°, where the groove root radius refers to the radius of the radial intersection of the grooved area and the non-grooved area, the groove width ratio refers to the ratio of the width of the step-type convergent spiral groove to the corresponding arc length on the circumference where it is located, and the groove length ratio refers to the ratio between the radial length of the step-type convergent spiral groove and the radial length of the sealing ring, that is, (groove root radius-inner radius) / (outer radius-inner radius). The step depths are 12μm, 9μm, and 6μm respectively, and are opened on the static ring. The end face of the static ring is made of cemented carbide or ceramic material. When the sealing pair is working, the sealing effect is achieved through the stable liquid film formed between the dynamic ring and the static ring. The liquid film fills the space between the dynamic ring and the static ring and fills the super-slip step-type convergent groove. Twelve super-slip step-type convergent grooves are opened on the surface of the stationary ring.

[0025] Opening a super-slip step-type convergent groove on the static ring is an effective way to achieve liquid film sealing. The design of the super-slip step-type convergent groove is based on the principle of fluid dynamics. It enhances the sealing effect by changing the flow path, flow velocity and pressure distribution of the fluid on the sealing surface. The super-slip step-type convergent groove can change the pressure distribution of the fluid on the sealing surface, so that the micro-flow field forms a local high-pressure area in the groove area. This pressure distribution helps to maintain the stability of the liquid film and inhibit the cavitation of the liquid film. When the fluid flows through the super-slip circumferential step-type convergent groove, the shape and depth of the groove guide the fluid to generate shear flow. This shear flow can generate a fluid dynamic pressure effect, thereby forming a stable and uniform liquid film between the sealing surfaces. Because the super-slip step-type convergent groove has three steps, three local high-pressure areas will be generated. Compared with the super-slip spiral groove, which only generates one local high-pressure area, the opening force of the liquid film is significantly improved and the cavitation effect of the liquid film is weakened; the super-slip circumferential step-type convergent groove has three stepped structures with gradually decreasing depths. This structure forms three different areas in the spiral groove. When the liquid flows through these three areas, due to the change in the geometric shape of the groove, different degrees of pressure accumulation will be generated on each step level, and then a pressure difference will be formed on different step levels. The accumulation of this pressure difference helps to enhance the fluid dynamic pressure effect. When the sealing ring rotates, the fluid flows in the stepped convergent groove. Due to the special structure of the circumferential stepped convergent groove, the fluid will generate vortices and backflow when flowing through the steps. These flow phenomena help to convert the kinetic energy of the fluid into pressure potential energy more efficiently, thereby improving the fluid dynamic pressure effect. The super-slip radial stepped convergent groove has three stepped structures with gradually decreasing depths, and its extension direction is different from that of the circumferential stepped convergent groove. When the radially flowing liquid hits the step surface, the liquid will produce a certain amount of backflow and deflection. The special shape of the groove improves the flow path of the liquid, converts the kinetic energy of the fluid into pressure potential energy, and thus increases the local fluid static pressure. The increase in static pressure can inhibit the leakage of liquid from the high-pressure side to the low-pressure side, thereby reducing the leakage rate; reduce the wear of the sealing surface: due to the existence of the super-slip step-type convergent groove, the direct contact between the sealing surfaces is greatly reduced, which helps to reduce friction heat and wear, thereby extending the service life of the seal. The super-slip surface is opened at the bottom of the step-type convergent groove to reduce the friction coefficient. The super-slip surface can reduce the adhesion shear force between the fluid in the groove area and the groove bottom surface, and can accelerate the flow field in the groove area to the windward side of the spiral groove under the influence of the rotating sealing ring, thereby enhancing the fluid dynamic pressure effect. The combination of the step-type convergent structure and the sliding design can produce a new flow field form, and its working principle is different from that of the step-type convergent groove or sliding groove design. The step-type convergent structure and sliding are not a simple superposition or combination, but through integration, the performance of the complex has a qualitative leap.

[0026] Example 1: Super-slip radial step-type convergent spiral groove sealing ring Figure 1As shown, under high pressure conditions, the radial flow velocity in the liquid film seal micro-flow field is relatively large. For this embodiment, the flow field flows from the high pressure side of the inner diameter of the sealing ring to the low pressure side of the outer diameter, and the sealing ring shown in Example 1 can be used.

[0027] In Example 1, when the rotating mechanical seal system is working, the dynamic ring rotates and the static ring remains stationary, and a relative motion is formed between the dynamic and static rings. Since the flow direction of the liquid in the groove area is from the step area with a large depth to the step area with a small depth, a flow channel convergence area will be formed between the sealing sub-end faces. Under the action of the pressure difference, the liquid enters the micro-scale gap between the dynamic and static rings from the inner diameter side of the sealing ring to form a lubricating liquid film. The relative rotation of the dynamic and static rings causes the liquid film to form a shear flow, and the medium pressure on the inner diameter side causes the liquid film to form a pressure flow. The shear flow and the pressure flow together form the flow path of the liquid film. In Example 1, the step depth of the super-slip radial step-type convergent spiral groove decreases step by step from the inner diameter side to the outer diameter side to form a convergence gap. As Figure 3 As shown in the figure, the liquid flows through the step inlet surface, step surface a, step surface b, and step surface c in sequence. The liquid first enters the step area with the largest depth to produce a certain amount of reflux and deflection, and then enters the next two steps in turn to produce a certain amount of reflux and deflection. The three steps make the flow field in the groove area more orderly, greatly improving the efficiency and performance of the seal. At the same time, the super-slip design of the groove bottom can reduce the friction and wear of the sealing pair. After the three steps, the liquid Figure 3 The pressure peak is formed on the windward side of the c-groove root of the mid-step surface. Figure 3 The mid-step inlet surface forms a low-pressure cavitation zone due to the expansion of the flow channel. The radial step-type convergent structure and sliding design significantly enhance the leakage suppression effect of the liquid film seal by combining the fluid dynamic pressure effect and static pressure effect and improving the fluid flow state. This design not only improves the sealing performance, but also extends the service life of the mechanical seal.

[0028] The following parameters are simulated and analyzed by numerical method: the outer radius of the sealing ring is 42.5mm, the inner radius of the sealing ring is 37.5mm, the ring thickness is 9mm, the groove root radius is 40mm, the groove width ratio is 0.5, the groove length ratio is 0.5, the number of grooves is 12, the groove area helix angle is 18°, the end face film thickness is 3μm, the step area groove depths are 6μm, 9μm and 12μm from small to large, the rotation speed is 6000r / min, and the fluid medium is liquid water. The calculation results show that compared with the super-slip spiral groove, the super-slip radial step-type convergent spiral groove can increase the open-leakage ratio by 2.79% when the pressure difference is 10MPa. When the pressure difference is 5MPa, the open-leakage ratio increases by 2.51%; when the pressure difference is 0MPa, the open-leakage ratio increases by 0.198%. Compared with the non-slip radial step-type convergent spiral groove, the super-slip radial step-type convergent spiral groove increases the open-leakage ratio by 0.31% when the pressure difference is 10MPa. When the pressure difference is 5MPa, the opening force increases by 3.38% and the opening-leakage ratio increases by 1.23%. When the pressure difference is 0MPa, the leakage rate increases by 5.88%, the opening force increases by 8.92%, and the opening-leakage ratio increases by 2.86%. It can be seen that under different pressure differences, the opening-leakage ratio of the super-slip radial step-type convergent spiral groove is greater than the opening-leakage ratio of the super-slip spiral groove and the non-slip radial step-type convergent spiral groove. Among them, the radial step-type convergent design of the groove significantly reduces the leakage rate, and the super-slip design greatly improves the opening force. The complex produced on the basis of the comprehensive design of the super-slip and radial step-type convergent structures can greatly balance the relationship between the opening force and the leakage rate, and further improve the comprehensive performance of the liquid film seal under high-pressure conditions as a whole.

[0029] The following numerical simulation is used to analyze the differences between the radial step-convergent spiral groove and the super-slip radial step-convergent spiral groove: Figure 5 Schematic diagram of the velocity vector comparison of the super-slip radial step-convergent spiral groove relative to the circumferential step-convergent spiral groove at the bottom of the groove, where (a) is the velocity vector diagram of the radial step-convergent spiral groove at the bottom of the groove, and (b) is the velocity vector diagram of the super-slip radial step-convergent spiral groove at the bottom of the groove. Figure 6 The velocity vector comparison diagram of the groove section of the super-slip radial step-type convergent spiral groove and the circumferential step-type convergent spiral groove parallel to the groove bottom, where (a) is the velocity vector diagram of the groove section of the radial step-type convergent spiral groove parallel to the groove bottom, and (b) is the velocity vector diagram of the groove section of the super-slip radial step-type convergent spiral groove parallel to the groove bottom. Figure 5 and Figure 6As shown in the figure, the super-slip radial step-convergent spiral groove has substantial advantages over the radial step-convergent spiral groove. Under the action of the viscous shear resistance at the bottom of the radial step-convergent spiral groove, the flow field is abnormally turbulent, the radial flow of the liquid film is dominant, and the circumferential flow mainly flows along the three step surfaces, which is not conducive to the formation of fluid dynamic pressure. The super-slip radial step-convergent spiral groove avoids this problem, making the flow field in the groove area orderly and the circumferential flow dominant, thereby generating a larger fluid dynamic pressure and improving the opening force. Under the influence of the convergent spiral groove, the flow velocity of the groove area flow field is close to the flow velocity of the liquid film in the non-groove area, while the flow velocity of the radial step-convergent spiral groove area is much smaller than the flow velocity of the liquid film in the non-groove area, which makes the generated opening force smaller. The flow field at the bottom of the super-slip radial step-convergent spiral groove is continuous, without obvious step dividing lines, while the flow field at the bottom of the radial step-convergent spiral groove is affected by the viscous shear resistance of the bottom surface, and the step surface dividing line is clearly visible. The discontinuity of the flow field will reduce the fluid dynamic pressure effect, thereby reducing the opening force of the liquid film. The flow velocity of the radial step-convergent spiral groove area flow field is obviously stratified, and gradually decreases along the step convergence direction. The flow velocity of each level of the flow field is similar, and is greatly affected by the step. The flow velocity of the super-slip radial step-convergent spiral groove area flow field is close, and the flow velocity of the three-step area is stable without significant changes. The kinetic energy generated by the fluid flow can be more efficiently converted into pressure potential energy, thereby improving the fluid dynamic pressure effect. Example 2: Super-slip circumferential step-type convergent spiral groove sealing ring Figure 2 As shown, when the rotation speed is high, the main flow direction of the micro-flow field in the liquid film seal is the circumferential shear flow. The sealing ring shown in Example 2 can be used.

[0030] In Example 2, when the liquid film seal is working, the dynamic ring moves circumferentially with the shaft, and the static ring is stationary. The dynamic ring closely fits the end face of the static ring by relying on the liquid pressure in the sealing cavity and the spring force, forming a stable and extremely thin liquid film in the axial gap between the static ring and the dynamic ring. With the end face of the static ring as the reference system, the liquid film rotates counterclockwise.

[0031] like Figure 2 , Figure 3 and Figure 4As shown in the figure, when the liquid film rotates circumferentially, the microflow field flows through the step inlet surface, step surface a, step surface b, and step surface c in turn. After the liquid enters the super-slip step-convergent spiral groove area, the circumferential flow hits each step surface step by step, and part of the liquid generates backflow. This backflow helps to enhance the dynamic pressure effect of the fluid in the groove, thereby improving the bearing capacity of the sealing surface. Because there are three steps, the liquid flows from the large mouth to the small mouth three times (that is, the liquid flows through the three flow channel convergence areas), thereby generating three fluid dynamic pressure effects, which significantly improves the opening force of the sealing surface. After the pressure accumulation of the three steps, the liquid is subjected to the greatest pressure on the windward side of the groove root, that is, at the step surface c, forming a pressure peak. At the same time, the liquid forms cavitation on the leeward side of the spiral groove, that is, at the step inlet surface a. The three significant fluid dynamic pressure effects increase the pressure in the low-pressure area to above the saturated vapor pressure, reducing the area where cavitation occurs. At the same time, the super-slip design of the groove bottom can reduce the viscous friction between the sealing surface and the liquid, thereby reducing the friction heat of the end surface, improving the sealing reliability, and saving energy. The super-slip design of the groove bottom and the circumferential step-type convergence design can significantly improve the sealing performance of the complex through integration.

[0032] The numerical method is also used to simulate and analyze the following parameters: the outer radius of the sealing ring is 42.5mm, the inner radius of the sealing ring is 37.5mm, the ring thickness is 9mm, the groove root radius is 40mm, the groove width ratio is 0.5, the groove length ratio is 0.5, the number of grooves is 12, the groove area helix angle is 18°, the end face film thickness is 3μm, the step area groove depths are 6μm, 9μm, and 12μm from small to large, the pressure difference is 0MPa, and the fluid medium is liquid water. The calculation results show that compared with the super-slip spiral groove, the super-slip circumferential step-convergent spiral groove has an increase of 6.83% in open-leakage ratio and a decrease of 90.86% in cavitation volume at a speed of 6000r / min; when the speed is 7000r / min, the open-leakage ratio increases by 6.90% and the cavitation volume decreases by 73.16%; when the speed is 8000r / min, the open-leakage ratio increases by 6.98% and the cavitation volume decreases by 56.28%. Compared with the non-slip circumferential step-convergent spiral groove, the open-leakage ratio of the super-slip circumferential step-convergent spiral groove increases by 5.93% and the cavitation volume decreases by 96.34% at a speed of 6000r / min; when the speed is 7000r / min, the open-leakage ratio increases by 9.05% and the cavitation volume decreases by 88.46%; when the speed is 8000r / min, the open-leakage ratio increases by 9.88% and the cavitation volume decreases by 80.71%. It can be seen that compared with the super-slip spiral groove and the non-slip circumferential step-convergent spiral groove, the super-slip circumferential step-convergent spiral groove has a larger open-leakage ratio and a smaller cavitation rate when the speed is higher. Among them, the circumferential step and the super-slip design of the groove bottom can both increase the opening force. Based on the comprehensive design of the groove bottom super-slip and the circumferential step-convergent structure, the comprehensive performance of the liquid film seal under high speed conditions has made a qualitative leap.

[0033] Figure 7 It is a comparison diagram of the velocity vectors of the super-slip circumferential step-convergent spiral groove relative to the circumferential step-convergent spiral groove at the bottom of the groove, where (a) is the velocity vector diagram of the circumferential step-convergent spiral groove at the bottom of the groove, and (b) is the velocity vector diagram of the super-slip circumferential step-convergent spiral groove at the bottom of the groove. Figure 8 It is a comparison diagram of the cavitation distribution of the super-slip circumferential step-convergent spiral groove versus the circumferential step-convergent spiral groove, where (a) is the cavitation distribution cloud diagram of the circumferential step-convergent spiral groove, and (b) is the cavitation distribution cloud diagram of the super-slip circumferential step-convergent spiral.

[0034] from Figure 7 , Figure 8 It can be seen that the super-slip circumferential step-convergent spiral groove is completely different from the circumferential step-convergent spiral groove and has substantial advantages: Under the action of the viscous shear resistance at the bottom of the circumferential step-convergent spiral groove, the flow field is abnormally chaotic, which is not conducive to the formation of fluid dynamic pressure. The super-slip circumferential step-convergent spiral groove avoids this problem, making the flow field in the groove area orderly, thereby generating greater fluid dynamic pressure and opening force.

[0035] For the super-slip circumferential step-convergent spiral groove, when the flow field passes through the first step, part of the liquid generates backflow, and the kinetic energy is converted into pressure potential energy; when passing through the second step, the liquid generates more backflow, and the kinetic energy is more efficiently converted into pressure potential energy, which improves the fluid dynamic pressure effect; when passing through the third step, the liquid generates less backflow, and the liquid flows faster to the windward side and the connection with the pressure inlet. For the circumferential step-convergent spiral groove, when the liquid flows through the three steps successively, the degree of liquid backflow decreases step by step, and the backflow speed is lower than that of the super-slip step-convergent spiral groove.

[0036] Under the influence of the super-slip circumferential step-convergent spiral groove, the flow velocity of the groove area flow field is close to the circumferential flow velocity of the liquid film in the non-groove area, while the flow velocity in the groove area of ​​the circumferential step-convergent spiral groove is much smaller than the flow velocity of the liquid film in the non-groove area, resulting in a smaller opening force.

[0037] The flow field at the bottom of the super-slip circumferential step-convergent spiral groove is continuous without obvious step dividing lines, while the flow field at the bottom of the circumferential step-convergent spiral groove is affected by the viscous shear resistance of the bottom surface, and the step surface dividing lines are clearly visible. The discontinuity of the flow field will reduce the fluid dynamic pressure effect, thereby reducing the opening force of the liquid film.

[0038] The distribution of eddy low-pressure areas in the flow fields of the two is obviously different, that is, the position and shape of the cavitation area are different. The cavitation area of ​​the super-slip circumferential step-convergent spiral groove is distributed in the non-groove area connected to the leeward side of the first step groove (from right to left), and the first step area connected to the leeward side of the second step. The two areas are separated, while the cavitation area of ​​the circumferential step-convergent spiral groove is distributed in the groove area and non-groove area on both sides of the leeward side of the first step groove, and the two areas are connected. The volume of the cavitation area is larger than that of the super-slip circumferential step-convergent spiral groove.

[0039] Therefore, the working mechanisms of the super-slip circumferential step-convergent spiral groove and the circumferential step-convergent spiral groove are essentially different, and the above information cannot be obtained by simple superposition and combination.

[0040] The above are all preferred embodiments of the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, various equivalent modifications to the present invention belong to the protection scope of the claims attached to this application.

Claims

1. A liquid super-slip step-type convergent groove sealing ring, comprising a sealing ring, characterized in that: A plurality of stepped convergent spiral grooves are evenly arranged on the inner diameter side of the sealing ring, the annular area close to the outer diameter side is a sealing dam, and a sealing weir is formed between adjacent spiral grooves. The stepped convergent spiral grooves are stepped, and a super slip surface is provided at the bottom of each stepped groove. The stepped convergent spiral grooves are arranged radially or circumferentially.

2. The liquid super-slip step-type convergent groove sealing ring according to claim 1, characterized in that: The radially stepped convergent spiral groove has a step extension direction that is radial, and the step depth decreases step by step from the inner diameter side to the outer diameter side, forming a convergent gap.

3. The liquid super-slip step-type convergent groove sealing ring according to claim 1, characterized in that: The circumferentially stepped convergent spiral groove has a step extension direction that is circumferential, and the step depth decreases or increases step by step along the circumference.

4. A liquid super-slip stepped convergent groove sealing ring according to claim 1, 2 or 3, characterized in that: The stepped convergent spiral groove has three steps, the step depths decrease step by step, and the step depths are 12 μm, 9 μm, and 6 μm respectively. The end face of the sealing ring is made of hard alloy or ceramic material.

5. The liquid super-slip stepped convergent groove sealing ring according to claim 4, characterized in that: The main dimensions of the sealing ring include: outer radius 42.5mm, inner radius 37.5mm, ring thickness 9mm, groove root radius 40mm, groove width ratio 0.5, groove length ratio 0.5, number of grooves 12, and groove area helix angle 18°.

6. The liquid super-slip step-type convergent groove sealing ring according to claim 1, characterized in that: The structure of the super-slip surface is as follows: there are micro-nanoscale gaps on the surface of the groove bottom, and a super-lubricant is arranged in the gaps. The liquid super-lubricant is injected into the micro-nanoscale gaps and forms a super-slip layer after solidification. The super-slip layer enables the liquid medium molecules at the interface between the liquid film and the super-slip layer to move freely along the bottom surface of the step-type convergent spiral groove, the slip speed of the liquid medium molecules approaches the moving speed of the moving surface, the slip length of the liquid medium molecules approaches positive infinity, and a super-slip surface is formed at the bottom of the step-type convergent spiral groove.

7. The liquid super-slip step-type convergent groove sealing ring according to claim 6, characterized in that: The surface of the groove bottom is porous or rough.

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