Dynamic seal structure and design method for a rotor device

Abstract

The application discloses a dynamic sealing structure and design method of a rotor device, and belongs to the field of rotor devices used for fluid mechanics experiments. The structure comprises a rotor inner cylinder, a rotor outer cylinder and a rotor cover plate with an annular partition. The chamber between the rotor cover plate and the upper edge of the rotor inner cylinder is divided into a first gap and a second gap which are axially adjacent by the partition, and a super-hydrophobic coating is sprayed on the solid wall surface between the two gaps and below the second gap to retain a drag-reducing gas film. The two gaps are respectively filled with sealing oil which has different viscosities, is insoluble in water and has a smaller density than water, forming a layered seal. The application also provides a corresponding design method, which optimizes the sealing structure parameters by establishing an additional torque model and setting the constraints of the rotor speed, the sealing oil viscosity and the sealing oil density. T 0> 50 T 3, can effectively prevent fluid leakage and gas intrusion at high speed rotation, and controls the additional torque introduced by the seal to be below 2% of the main torque, thereby significantly improving the accuracy of high-precision fluid friction torque testing.

Description

Technical Field

[0001] This invention belongs to the field of rotor devices for fluid mechanics experiments, and specifically relates to a dynamic sealing structure and design method for a rotor device. Background Technology

[0002] As a classic experimental device in fluid mechanics, the rotor apparatus creates a controllable laminar or turbulent flow field within its annular gap by driving the relative rotation of coaxially mounted inner and outer cylinders. By measuring the torque experienced by the rotating components using high-precision sensors, the frictional resistance between the fluid and the solid wall can be directly obtained, thus enabling the study of key scientific issues such as drag reduction characteristics and flow regime transitions. Compared to large circulating water tunnels or towed pools, the rotor apparatus offers significant advantages such as compact structure, lower cost, and easy and precise control of experimental parameters, making it an indispensable tool for the accurate measurement of fluid frictional resistance.

[0003] However, as fluid mechanics research advances towards higher Reynolds numbers and more precise resistance measurements, rotor devices face a long-standing core contradiction: the fundamental conflict between the reliability of dynamic sealing and the accuracy of torque measurement. At high speeds, the experimental fluid (often an aqueous solution) within the gap tends to be ejected, and external air may also infiltrate, disrupting the flow field uniformity and leading to measurement failure; therefore, dynamic sealing is essential. On the other hand, to capture minute changes in frictional resistance, any additional torque introduced for non-measurement purposes must be strictly suppressed to an extremely low level.

[0004] Existing conventional dynamic sealing solutions cannot meet this stringent requirement:

[0005] 1. Contact seals (such as O-rings and mechanical seals): Their inherent solid friction introduces unpredictable and unstable additional torque of a considerable or even greater magnitude, completely undermining the basis for micro-torque measurement.

[0006] 2. Labyrinth seal: Although it is a non-contact type, its complex flow channels often require the filling of high-viscosity sealing grease to suppress gas exchange. In narrow sealing gaps of millimeters or even sub-millimeters, high-viscosity grease will generate a non-negligible viscous shear torque, the value of which may be on the same order of magnitude as the torque of the fluid being measured, seriously interfering with the measurement results.

[0007] Therefore, there is an urgent need to invent a completely new dynamic sealing principle and structure to fundamentally reconcile the contradiction between sealing reliability and torque measurement accuracy. Summary of the Invention

[0008] The technical problem to be solved:

[0009] To overcome the shortcomings of existing technologies, this invention provides a dynamic sealing structure and design method for a rotor device, proposing a sealing method that combines superhydrophobic interface airlock drag reduction with a two-stage viscosity difference oil seal. The stable gas film formed by the superhydrophobic coating in the narrow gap fundamentally reduces the effective contact area between the rotating wall and the sealing oil, significantly reducing the source of viscous resistance. Furthermore, the partitioned filling with low-viscosity oil further reduces residual fluid shear force. The synergistic effect of these two methods enables a sealing performance comparable to or even better than traditional seals, while reducing the additional frictional torque by more than an order of magnitude, reaching a negligible level (less than 2%). T 0). This invention overcomes the shortcomings of conventional sealing schemes in existing rotor devices that cannot meet the extremely low additional torque requirements for micro-torque measurement while ensuring sealing reliability under high-speed rotation.

[0010] The technical solution of the present invention is: a dynamic sealing structure for a rotor device, the rotor device comprising a rotor inner cylinder and a rotor outer cylinder concentrically arranged and forming an annular gap between them to accommodate experimental fluid, and a rotor cover plate covering the top of the annular gap; the rotor inner cylinder extends axially toward the inner hole of the rotor cover plate to form a two-section stepped shaft structure, wherein the large-diameter section is located between the small-diameter section and the rotor inner cylinder, and the small-diameter section constitutes the upper edge of the rotor inner cylinder; the dynamic sealing structure is located between the rotor cover plate and the two-section stepped shaft, comprising:

[0011] A partition unit is provided on the inner wall of the rotor cover plate to divide the top sealing cavity formed by the rotor cover plate and the upper edge of the rotor inner cylinder into a first gap and a second gap arranged along the axial direction.

[0012] The layered sealing medium unit includes a first sealing oil filled in a first gap and a second sealing oil filled in a second gap with a viscosity higher than that of the first sealing oil. Both the first sealing oil and the second sealing oil are immiscible with the experimental fluid and have a density lower than that of the experimental fluid.

[0013] The superhydrophobic interface unit is formed on the relative solid wall surface of the separator unit and the upper edge of the rotor inner cylinder, and on the relative solid wall surface of the rotor cover plate and the large diameter section, to retain an air film between the solid wall surface and the sealing medium to reduce the solid-liquid contact area.

[0014] The first gap, the second gap, the superhydrophobic interface unit, and the layered sealing medium unit work together to form a collaborative sealing system that prevents experimental fluid from overflowing and external gas from seeping in under dynamic rotation, while controlling the additional resistance torque introduced by the sealing to below a preset threshold.

[0015] A further technical solution of the present invention is: the partition unit is an annular partition plate disposed on the inner wall of the rotor cover plate; the first gap is the space between the inner wall of the rotor cover plate located above the annular partition plate and the relatively solid wall surface of the upper edge of the rotor inner cylinder; the second gap is the space arranged axially between the lower surface of the annular partition plate and the stepped surface of the two-section stepped shaft.

[0016] A further technical solution of the present invention is: the rotor cover plate is an annular disk structure with an inner hole, and the opening of the outer end face extends radially into the hole to form an annular shielding surface. The inner diameter of the annular shielding surface is smaller than the outer diameter of the upper edge of the rotor inner cylinder, which is used to cover the opening of the top sealing cavity; the outer edge of its inner end face extends radially outward to form a flange structure that is sealed and connected with the rotor outer cylinder.

[0017] A further technical solution of the present invention is: the superhydrophobic interface unit includes a superhydrophobic coating sprayed on the relative solid wall surfaces of the annular partition and the upper edge of the rotor inner cylinder, and on the relative solid wall surfaces of the rotor cover and the large diameter section; an air film is formed in the annular cavity between the first sealing oil and the second sealing oil, and between the second sealing oil and the experimental fluid.

[0018] A further technical solution of the present invention is: the outer radius of the small-diameter segment of the two-section stepped shaft is R 11 The inner radius of the rotor cover plate is R 12 The outer radius of the large-diameter section of the two-section stepped shaft is R 21 Satisfying Relationship: R 11 < R 21 < R 12 , R 11 and R 12 The value range is 1 / 6 R 1 to 1 / 2 R 1, and R 12 - R 11 >2mm, of which R 1 represents the outer radius of the rotor inner cylinder.

[0019] A further technical solution of the present invention is: the height of the sealing oil in the first gap. L 1. Satisfies: 3mm≤ L 1≤10mm; The height h of the sealing oil in the second gap must satisfy: 5mm≤h≤15mm.

[0020] A further technical solution of the present invention is: the viscosity of the low-viscosity sealing oil used to fill the first gap is 0.1 Pa·s to 0.9 Pa·s, and the viscosity of the high-viscosity sealing oil used to fill the second gap is 1 Pa·s to 5 Pa·s.

[0021] A method for designing a dynamic sealing structure for a rotor device includes the following steps:

[0022] Step 1: Determine the main torque reference: Based on the target experimental Reynolds number and rotational speed, determine the dimensions of the rotor inner cylinder and rotor outer cylinder; based on computational fluid dynamics, simulate and calculate the surface friction torque generated solely by the experimental fluid within the predetermined rotational speed range of the rotor device; the main torque is... T 0;

[0023] Step 2: Establish the additional torque model and set constraints: Establish the additional resistance torque generated by the sealing oil in the first and second gaps. T 1 and T 2. Calculation model; setting the total additional torque that the sealing structure must meet. T 3= T 1+ T 2 is much smaller than the main torque T The constraint of 0, i.e. T 0> · T 3, of which, The preset coefficient is much greater than 1;

[0024] Step 3: Collaborative Optimization of Sealing Structure Parameters: Under the constraints described, and prioritizing sealing reliability, the geometric dimensions of the first and second gaps, as well as the viscosity of the first and second sealing oils, are collaboratively and iteratively optimized to achieve the desired total additional torque. T 3 minimize;

[0025] Step 4: Implement the sealing structure: Based on the optimized parameters, process a rotor cover plate with partition units, prepare superhydrophobic interface units on the specified wall surface, and sequentially fill with first sealing oil and second sealing oil of specified viscosity and height.

[0026] A further technical solution of the present invention is: in step 2, a preset coefficient is used. ≥50; Additional resistance torque T 1 and T 2. Calculate using the following formulas respectively:

[0027]

[0028]

[0029] in, R 11The outer radius of the smaller diameter segment of the two-section stepped shaft. R 12 Where is the inner radius of the rotor cover plate. R 21 The outer radius of the large-diameter section of the two-segment stepped shaft. L 1 represents the height of the sealing oil in the first gap. η 1 represents the viscosity of the sealing oil in the first gap; h represents the height of the sealing oil in the second gap. η 2 represents the viscosity of the sealing oil in the second gap; This represents the rotational speed of the rotor's inner cylinder.

[0030] A further technical solution of the present invention is: the specific process of collaborative iterative optimization in step 3 includes:

[0031] In satisfying R 12 - R 11 >2mm, 3mm≤ L Within the feasible engineering range of 1≤10mm, 5mm≤h≤15mm, adjustments can be made. R 11 , R 12 , L 1, h, η 1. η Combinations of values ​​for 2;

[0032] For each set of parameters, calculate its maximum T3 value within the target speed range;

[0033] Filter out all that meet the requirements T 0min > ·max( T 3) parameter combinations, where T 0min This refers to the minimum main torque within the predetermined speed range;

[0034] From the selected combinations, choose the one that makes max( T 3) The smallest parameter combination is taken as the final optimization result.

[0035] Beneficial effects

[0036] The beneficial effects of this invention are as follows: The rotor device dynamic sealing structure and its design method provided by this invention fundamentally solve the long-standing contradiction between "dynamic sealing reliability" and "micro-torque measurement accuracy" in high-precision fluid dynamics testing. Specifically, it includes the following outstanding advantages:

[0037] 1. This invention overcomes the problem of air easily entering the rotor gap during high-speed rotation of the rotor device, affecting experimental accuracy. By employing a dual-stage gap separation structure, the annular gap between the rotor cover plate and the upper edge of the rotor inner cylinder is divided into two sealing chambers: a first gap and a second gap, achieving layered sealing. The inner wall of the rotor cover plate is designed with an annular partition to divide the gap into sections to accommodate different sealing media. A superhydrophobic coating is sprayed on the opposing solid wall surfaces of the annular partition and the upper edge of the rotor inner cylinder, as well as on the opposing solid wall surfaces of the rotor cover plate and the large-diameter section of the two-stage stepped shaft, forming a hydrophobic interface. With the help of the superhydrophobic coating, a stable gas film can be retained in these two narrow gaps, preventing the sealing oil from leaking out under gravity or centrifugal force and preventing liquid from climbing along the interface. Furthermore, an annular shielding surface is provided on the upper surface of the rotor cover plate to cover the gap opening and prevent oil from being thrown out during high-speed rotation. The above optimized design makes the dynamic sealing structure simple, compact, and easy to process and assemble, while achieving efficient and reliable sealing through the synergistic effect of the dual-stage gap and the gas film.

[0038] 2. This invention achieves dynamic sealing by using a simple stepped sealing structure combined with an interface sprayed with a superhydrophobic coating and layered filling with sealing oil, introducing only negligible additional frictional torque. Compared to traditional sealing ring solutions, the increased frictional resistance of this invention's sealing structure is almost negligible and will not affect the accuracy of rotor torque testing. Compared to conventional labyrinth seals and other methods, this structure is simpler and easier to use, and through reasonable structural optimization, it facilitates the quick installation and removal of the rotor cover.

[0039] 3. This invention proposes a liquid dynamic sealing scheme in which two separate gaps are filled with sealing oils of different viscosities: a high-viscosity sealing oil is filled in the second gap closest to the sealed medium, and a low-viscosity sealing oil is filled in the upper first gap. Both selected sealing oils are immiscible with water and have a density less than water, ensuring that the oil floats on the water surface and does not sink, thus preventing contamination of the main medium when the rotor inner cylinder stops rotating. Compared with traditional structures using single grease seals or dry labyrinth seals, this differentiated material combination ensures sealing performance while simplifying the structure and making maintenance easier.

[0040] 4. This invention optimizes various design parameters to achieve extremely low frictional resistance in the dynamic sealing structure while maintaining a good sealing effect. The design limits the dimensions of the first and second gaps and the amount of sealing oil within a reasonable range, avoiding excessive oil thickness which would significantly increase viscous resistance, and also preventing insufficient oil from disrupting the seal continuity. By utilizing the gas film formed by the superhydrophobic coating to reduce the liquid-solid contact area, and combined with the use of low-viscosity oil, the additional frictional torque of the rotor inner cylinder is controlled to a very small range. Actual calculation results show that the total resistance torque introduced by this sealing structure is... T 3 is much smaller than the frictional torque of the fluid in the rotor experiment. T0, satisfying the requirements at all operating speeds. T 0 > 50 T Design requirements 3. The additional torque contributed by the sealing structure is less than 2% of the rotor's own torque, which is negligible and does not affect the accuracy of rotor torque testing.

[0041] like Figure 8 As shown, the torque-time curves of the experimental fluid at a rotational speed of 800 r / min are compared before and after using the sealing method of the present invention: the solid line is the torque curve measured when the sealing structure of the present invention is used, and the dashed line is the torque curve when the sealing structure of the present invention is not used. It can be seen that without proper sealing, the experimental fluid in the gap is continuously thrown out during long-term operation, and air enters the gap, causing the torque value to gradually decrease; while with the sealing structure provided by the present invention, the experimental fluid is effectively confined within the gap, the torque remains stable, and the sealing effect is fully achieved. Attached Figure Description

[0042] Figure 1 This is an overall schematic diagram of the rotor device in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the rotor inner cylinder in an embodiment of the present invention;

[0044] Figure 3 This is a cross-sectional schematic diagram of the rotor cover plate in an embodiment of the present invention;

[0045] Figure 4 This is a top view of the rotor cover plate in an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the sealing structure in an embodiment of the present invention;

[0047] Figure 6 This is a schematic diagram of the rotor outer cylinder in an embodiment of the present invention;

[0048] Figure 7 The main torque of the rotor at different speeds T 0 and the total resistance torque of the sealing oil T 3. Comparison curve;

[0049] Figure 8 The graph shows a comparison of the change in fluid torque over time before and after using the sealing structure of this invention, under the condition of a rotor inner cylinder at a rotational speed of 800 r / min.

[0050] Explanation of reference numerals in the attached drawings: 1 is the rotor cover plate, 2 is the rotor outer cylinder, 3 is the rotor inner cylinder, 4 is the frame, 5 is the rotor shaft, 6 is the upper edge of the rotor inner cylinder, 7 is the first gap, 8 is the annular partition, 9 is the second gap, 10 is the bolt, 11 is the large-diameter section of the two-section stepped shaft, 12 is the third gap, 13 is the liquid inlet, 14 is the experimental fluid in the third gap, 15 is the superhydrophobic coating, 16 is the high-viscosity sealing oil in the second gap, 17 is the low-viscosity sealing oil in the first gap, 18 is the first through hole, 19 is the sealing ring groove, and 20 is the second through hole.

[0051] 21 is the curve of the total torque contributed by the sealing oil at different speeds as a function of rotational speed; 22 is the curve of the total torque of the rotor test at different speeds as a function of rotational speed; 23 is the curve of the experimental fluid torque as a function of time after adopting the sealing structure of the present invention; 24 is the curve of the experimental fluid torque as a function of time when the sealing structure of the present invention is not adopted. At this time, because some fluid is thrown out under high-speed rotation, gas enters the rotor gap, resulting in a gradual decrease in torque over time. Detailed Implementation

[0052] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0054] Existing patents such as JP2015175841A focus on bearing protection, end face correction, or temperature field uniformity improvement, and the sealing methods they employ are still based on traditional approaches. While patents such as CN113959910A and JP2009063505A involve rotation measurement and sealing, their application scenarios (such as drilling fluid measurement and blood viscosity analysis) do not meet the requirements for absolute accuracy of torque measurement and minimization of additional torque that this invention addresses in its fundamental research on fluid mechanics.

[0055] Therefore, existing technologies lack a solution that can ensure reliable sealing of the experimental fluid under high-speed dynamic conditions while keeping the additional frictional torque it introduces to a negligible level. This challenge limits the development of rotor devices towards higher precision and higher speed (corresponding to higher Reynolds numbers) testing capabilities.

[0056] Based on the problems existing in the prior art, this invention proposes a dynamic sealing structure for a rotor device. The rotor device includes an inner rotor cylinder and an outer rotor cylinder concentrically arranged and forming an annular gap between them to accommodate experimental fluid, and a rotor cover plate covering the top of the annular gap. The inner rotor cylinder extends axially into the inner hole of the rotor cover plate to form a two-section stepped shaft structure, wherein the larger diameter section is located between the smaller diameter section and the inner rotor cylinder, and the smaller diameter section constitutes the upper edge of the inner rotor cylinder. The dynamic sealing structure is located between the rotor cover plate and the two-section stepped shaft, including:

[0057] A partition unit is provided on the inner wall of the rotor cover plate to divide the top sealing cavity formed by the rotor cover plate and the upper edge of the rotor inner cylinder into a first gap and a second gap arranged along the axial direction.

[0058] The layered sealing medium unit includes a first sealing oil filled in a first gap and a second sealing oil filled in a second gap with a viscosity higher than that of the first sealing oil. Both the first sealing oil and the second sealing oil are immiscible with the experimental fluid and have a density lower than that of the experimental fluid.

[0059] The superhydrophobic interface unit is formed on the relative solid wall surface of the separator unit and the upper edge of the rotor inner cylinder, and on the relative solid wall surface of the rotor cover plate and the large diameter section, to retain an air film between the solid wall surface and the sealing medium to reduce the solid-liquid contact area.

[0060] The first gap, the second gap, the superhydrophobic interface unit, and the layered sealing medium unit work together to form a collaborative sealing system that prevents experimental fluid from overflowing and external gas from seeping in under dynamic rotation, while controlling the additional resistance torque introduced by the sealing to below a preset threshold.

[0061] This invention creatively uses the additional torque of the sealing structure itself as a core design indicator and strictly controls it. Through the synergistic effect of "superhydrophobic coating solid-gas drag reduction" and "zoned low-viscosity oil seal", the total additional torque introduced by the sealing structure is reduced. T 3. The requirements have been reduced to extremely low levels. Theoretical calculations and experimental verification have shown that the requirements can be met at all operating speeds. T 0 > 50 T The stringent design principle of 3 means that the additional torque is less than 2% of the main fluid torque. This indicator means that the interference of the sealing structure on torque measurement has changed from "non-negligible" in the traditional solution to "near transparent", laying the foundation for obtaining high-fidelity fluid friction resistance data and realizing a fundamental leap in measurement accuracy.

[0062] The above technical solution will be further described below with reference to the accompanying drawings and embodiments:

[0063] In one embodiment, a dynamic sealing structure for a rotor device and its specific design method are provided. This device is primarily designed for high Reynolds numbers (reaching 1.0 × 10⁻⁶). 5 The high-speed (circumferential linear velocity exceeding 8 m / s) fluid dynamics test conditions aim to achieve reliable dynamic sealing while controlling the additional torque introduced by the sealing structure to an extremely low level (less than 2% of the main fluid torque) to meet the requirements of high-precision friction resistance measurement.

[0064] I. Composition of dynamic sealing structure:

[0065] Reference Figure 1 As shown, the dynamic sealing structure of this embodiment is integrated into a coaxial rotor device, which mainly includes a rotor outer cylinder 2, a rotor inner cylinder 3, and a rotor cover plate 1.

[0066] 1. Rotor inner cylinder 3: Refer to Figure 2 As shown, it is a cylindrical shell with a rotor shaft 5 fixedly mounted at the center, which is driven to rotate by an external motor. The top of it is machined with a two-section stepped shaft including a stepped shoulder, wherein the large-diameter section is located between the small-diameter section and the rotor inner cylinder 3, and the small-diameter section forms the upper edge 6 of the rotor inner cylinder.

[0067] 2. Rotor outer cylinder 2: Refer to Figure 6 As shown, it is a hollow cylinder, fixedly installed on the frame 4. Its inner diameter is larger than the outer diameter of the rotor inner cylinder. After the two are installed concentrically, they form an annular third gap 12, which is used to hold the experimental fluid 14 (such as an aqueous solution). The rotor outer cylinder has shoulder planes on the upper and lower edges, and first through holes 18 are evenly opened in the circumference for bolt connection. It also has sealing ring grooves to achieve static sealing.

[0068] 3. Rotor cover plate 1: Refer to Figure 3 and 4 As shown, a ring-shaped disk structure with an inner hole is fixed to the upper edge of the rotor outer cylinder by circumferential bolts. An integrally formed annular partition 8 is provided on the inner wall of the hole. The annular partition 8 is formed by extending radially towards the central axis from the axially central region of the inner wall of the rotor cover plate 1, dividing the annular cavity between the rotor cover plate 1 and the upper edge 6 of the rotor inner cylinder into two gaps in the axial direction, as shown... Figure 5 As shown:

[0069] First gap 7: The space between the inner wall of the rotor cover plate 1 located above the annular partition plate 8 and the relatively solid wall surface of the upper edge 6 of the rotor inner cylinder is the first gap 7.

[0070] The second gap 9 is located below the annular partition 8 and is the space enclosed by the inner wall of the rotor cover plate 1, the upper edge 6 of the rotor inner cylinder, and the stepped surface of the two-section stepped shaft. It is adjacent to the experimental fluid 14. In addition, the orifice on the outer end face of the rotor cover plate extends radially into the hole to form an annular shielding surface. The inner diameter of the annular shielding surface is smaller than the outer diameter of the upper edge 6 of the rotor inner cylinder. It is used to cover the opening of the top sealing cavity to prevent oil from splashing out during high-speed rotation.

[0071] 4. Interface and Media:

[0072] Superhydrophobic coatings are sprayed onto the solid surfaces of the annular partition 8 and the upper edge 6 of the rotor inner cylinder, as well as the solid surfaces of the rotor cover plate 1 and the large-diameter section of the two-section stepped shaft.

[0073] The first gap is filled with a low-viscosity sealing oil (e.g., polybutene oil with a viscosity of about 0.5 Pa·s).

[0074] The second gap is filled with a high-viscosity sealing oil (e.g., dimethyl silicone oil with a viscosity of about 1 Pa·s).

[0075] Both sealing oils are immiscible with water and have a density less than water, ensuring they can float on aqueous solutions.

[0076] An air film is formed in the annular cavity between the first and second sealing oils, and between the second sealing oil and the experimental fluid.

[0077] II. The design method of dynamic sealing structure in rotor device includes the following steps:

[0078] Step 1. Determine the dimensional parameters of the rotor's inner and outer cylinders:

[0079] Based on the target Reynolds number Re and the test torque T Determine the range of 0 and the required measurement accuracy to determine the outer radius of the rotor inner cylinder. R 1. Rotor inner cylinder height H and rotor outer cylinder inner radius R 2. The formula for calculating the Reynolds number is:

[0080] Re= R 1ζd /

[0081] Where ζ represents angular velocity in rad / s; d represents the width of the gap between the inner and outer cylinders of the rotor, d= R 2- R 1. The unit is meters (m). The kinetic viscosity of the experimental fluid within the gap is expressed in m. 2 / s.

[0082] In this embodiment, the design is specifically for high Reynolds number and high speed operating conditions: a Reynolds number of 1.0 × 10⁻⁶ is required.5 The circumferential linear velocity of the rotor inner cylinder exceeds 8 m / s, corresponding to a rotational speed of not less than 800 r / min, and taking... R 1 / R 2 = 0.7~0.9. Rotor inner cylinder height H ≥ 2 R 1.

[0083] In summary, the rotor inner cylinder outer radius requirement meets this condition. R 1≥0.1m.

[0084] Step 2. Determine the torque between the concentric cylinders of the rotor assembly. T 0:

[0085] Based on the dimensional requirements in step 1, a concentric cylindrical flow field model was established. ICEM software was used to generate a structured hexahedral mesh in the flow field region to reduce the number of meshes and accelerate solution convergence. The flow medium was set as water, with the following boundary conditions: the inner wall of the rotor outer cylinder is a stationary wall, and the outer wall of the rotor inner cylinder rotates at a set speed. Steady-state simulation of the coaxial cylindrical flow field was performed using Fluent software. A pressure-based solver and the SST k-ω turbulence model were selected to more accurately simulate the flow near the wall. Through simulation calculations, the frictional torque on the surface of the rotor inner cylinder at different speeds was obtained. The calculation process is as follows:

[0086] Continuity equation:

[0087]

[0088] in, express The instantaneous value of velocity in the direction, in m / s; express Spatial coordinate components of direction, in meters.

[0089] Momentum equation:

[0090]

[0091] in, express Spatial coordinate components of direction, in meters. express The instantaneous value of velocity in the direction, in m / s; Indicates time, in seconds; ρ This indicates fluid density, expressed in kg / m³. 3 , P This represents the average pressure, expressed in Pa. This represents the Reynolds stress term.

[0092] The equations for the SST k-ω model are:

[0093]

[0094]

[0095] in, k Represents turbulent kinetic energy, with units of m. 2 / s 2 ; ω This indicates the specific dissipation rate, with units of 1 / s; P k Represents the turbulent kinetic energy generation term; μ t This represents the final turbulent eddy viscosity, expressed in Pa·s. μ This indicates dynamic viscosity, expressed in Pa·s.

[0096] Turbulent eddy viscosity is calculated using the SST k-ω model, whose basic expression is:

[0097]

[0098] in, This indicates unrestricted turbulent eddy viscosity; α , , β , , σ k , σ ω , σ ω2 The model constants are determined by the mixture function; F 1 represents the first mixture function. F 2 represents the second mixing function. Both are model mixing functions in the SST k-ω turbulence model, used to achieve a smooth transition of model parameters in different regions.

[0099] To avoid excessive eddy viscosity in the free shear flow region, an eddy viscosity limiter is introduced, resulting in the following final turbulent eddy viscosity:

[0100]

[0101] in, The modulus of the strain rate tensor is represented by, where,

[0102]

[0103] =0.31

[0104] Turbulent kinetic energy generation term for:

[0105]

[0106]

[0107] in, Represents the Kronecker symbol; express The instantaneous value of velocity in the direction, in m / s; express Spatial coordinate components of direction, in meters;

[0108] First mixture function F 1 is:

[0109] F 1 = tanh (Φ1) 4 )

[0110]

[0111]

[0112] Second mixture function F 2 is:

[0113] F 2 = tanh (Φ2) 2 )

[0114]

[0115] in, This represents the normal distance to the wall, in meters (m). Indicates the cross-diffusion term; This indicates the kinetic viscosity of the experimental fluid within the gap, expressed in m² / s.

[0116] Determine the model constants:

[0117] Model constants pass F 1. Linear mixture:

[0118] For any model constant : = F 1 1+(1 F 1) 2.

[0119] set up ;

[0120] Therefore: ; .

[0121] The values ​​of the constants in the above equations are shown in the table below:

[0122]

[0123] Wall treatment and low Reynolds number correction:

[0124] Near-wall damping function :

[0125]

[0126] in: Represents the near-wall damping function in the region far from the wall. The limit value of is dimensionless and is taken as 1; , representing the near-wall damping function near the wall. The limit value; This represents the empirical constant of the SST k-ω model; it is dimensionless and takes the value 0.072. Represents the turbulent friction Reynolds number, which is dimensionless and used to describe the ratio of turbulent inertial effects to viscous effects; R k The empirical constant representing the damping function is dimensionless and is taken as 6. All the model constants mentioned above adopt the recommended values ​​from the standard SST k-ω model.

[0127] On the wall surface, FLUENT calculates the shear stress as follows:

[0128] Laminar sublayer with no slip condition:

[0129]

[0130] in, This represents the wall shear stress, and the subscript "wall" indicates that the physical quantity is taken at the rotor surface wall. represents the tangential velocity component, in m / s; r represents the radial coordinate, in m.

[0131] For the SST k-ω model, FLUENT uses automatic wall handling: low Reynolds number formulas are used in viscous layers; wall functions are used in logarithmic layers; and automatic switching is based on mesh size.

[0132] For a rotating wall, the torque is calculated as follows:

[0133]

[0134] in, R 1 represents the outer radius of the rotor inner cylinder. Indicates tangential shear stress. Represents the area of ​​a microelement; θ Represents circumferential angular coordinates, in rad; z This represents the axial coordinate, in meters (m).

[0135] In FLUENT, it is discretized as follows:

[0136]

[0137] in, This represents the number of discrete mesh wall elements on the rotor surface; Indicates the first The tangential shear stress of each wall element, in Pa; Indicates the first The distance from the center of each wall unit to the axis of rotation is expressed in meters (m). Indicates the first Area of ​​each wall unit, in m² 2 .

[0138] The frictional torque on the inner surface of the rotor cylinder at different speeds can be calculated using the above methods. T 0.

[0139] Step 3. Establish the sealing additional torque model and design constraints:

[0140] (I) Calculate the contribution of the filling oil in the first gap to the torque:

[0141] The first gap can be regarded as a small coaxial rotor system. The resistance torque of the oil in the gap on the rotor is calculated according to the following formula:

[0142]

[0143] in, R 11 This indicates the outer radius of the smaller diameter segment of the two-segment stepped shaft. R 12 This indicates the inner radius of the rotor cover plate. L 1 indicates the height of the sealing oil in the first gap. This indicates the rotational speed of the rotor's inner cylinder, expressed in r / min. η 1 indicates the viscosity of the sealing oil in the first gap, in Pa·s. The first gap is filled with sealing oil with a viscosity of 0.1 Pa·s to 0.9 Pa·s.

[0144] (II) Calculate the contribution of the filling oil in the second gap to the torque:

[0145] The second gap can be considered as a system where a hollow disk drives the fluid to rotate. The resistance torque of the oil inside the gap on the rotor is calculated according to the following formula:

[0146]

[0147] in, R 21The outer radius of the large-diameter section of the two-section stepped shaft is represented by h, and the height of the sealing oil in the second clearance is represented by h. η 2 indicates the viscosity of the sealing oil in the second gap, in Pa·s. The second gap is filled with oil with a viscosity of approximately 1 Pa·s to 5 Pa·s as the sealing medium. Considering the influence of oil fluctuations during high-speed rotor rotation, the difference between the inner wall radius of the annular baffle and the shoulder radius of the rotor inner cylinder is set to 1 mm, i.e. R 12 - R 21 =1mm.

[0148] To minimize the impact of the sealing structure on the test results, the design must meet the following requirements. T 0 > 50 T 3, of which T 3= T 1+ T 2.

[0149] Step 4. Collaborative optimization to determine key parameters of the sealing structure:

[0150]

[0151] Simplifying, we get:

[0152]

[0153] Under the constraints and basic sealing requirements mentioned above, the sealing structure parameters are optimized collaboratively:

[0154] 1. Radial dimension: For R 11 and R 12 When its value is too large, the volume of the sealing cavity formed between the upper end face of the rotor inner cylinder and the lower end face of the rotor cover plate is too large, which will introduce a large additional resistance torque after being filled with liquid. And when... R 11 and R 12 If the flow is too small, the localized flow at the top edge of the rotor's inner cylinder may become extremely unstable, potentially causing the internal liquid to be thrown out and affecting the stability of the fluid within the concentric cylinder gap during high-speed operation. Therefore... R 11 and R 12 The range is generally in the range of 1 / 6 R 1~1 / 2 R 1. Furthermore, a superhydrophobic coating needs to be applied between the two, and sealing oil needs to be added; therefore, the constraint conditions are met. R 12 - R 11 >2mm.

[0155] 2. Axial dimension: Height of sealing oil layer L 1 and h have a significant impact on the additional torque and sealing performance. When L When the values ​​of 1 and h are too large, excessive viscous resistance torque will be introduced, affecting the experimental results; while when the values ​​are too small, the amount of sealing oil in the gap will be insufficient, and the oil will easily be thrown out during high-speed rotation, failing to guarantee the sealing effect. Taking into account both the convenience of the oiling operation and the sealing performance requirements, this invention requires 5mm ≤ h ≤ 15mm, 3mm ≤ L 1≤10mm.

[0156] 3. Oil viscosity: Based on calculations, the viscosity of the sealing oil in the first gap is selected. η 1 = 0.5 Pa·s, viscosity of sealing oil in the second gap η 2 = 1 Pa·s.

[0157] Calculations have verified that, within the speed range of 100-800 r / min, the total additional torque... T 3. The maximum value is much smaller than the main torque at the corresponding speed. T 0, fully satisfied T 0>50 T The design requirement for part 3 is that the additional torque contribution rate is less than 2%.

[0158] Based on the above constraints, the feasible range of each parameter can be determined.

[0159] Step 5. Spray a superhydrophobic coating:

[0160] First, a superhydrophobic coating is sprayed onto the relatively solid wall surfaces of the annular partition 8 and the upper edge 6 of the rotor inner cylinder, as well as the relatively solid wall surface of the rotor cover plate 1 and the large-diameter section, as illustrated in the diagram. Figure 5 The thickened black lines in the image should be left to air dry for 12 hours.

[0161] Step 6. Install the rotor assembly:

[0162] Install the rotor outer cylinder 2 onto the frame 4: Place a sealing ring in the sealing groove on the lower edge of the rotor outer cylinder and ensure it seals against the frame 4; then align the eight first through holes 18 on the lower shoulder of the rotor outer cylinder with the corresponding eight threaded holes on the frame 4, insert bolts, and tighten them to secure it. Next, install the rotor inner cylinder 3 onto the bearing at the center liquid inlet of the frame. Finally, mate the rotor cover plate 1 with the rotor outer cylinder 2, place a sealing ring at the contact point and press it down, insert bolts and tighten them while aligning the eight through holes on the upper shoulder of the rotor cover plate 1 and the rotor outer cylinder 2.

[0163] Step 7. Inject the experimental fluid:

[0164] The experimental fluid is injected into the third gap through the inlet below the frame 4 using a diaphragm pump. When the liquid level in the third gap 12 is observed to be flush with the lower surface of the rotor cover plate 1, the diaphragm pump valve is closed to stop the injection.

[0165] Step 8. Add sealing oil to achieve a seal:

[0166] First, high-viscosity sealing oil is added to the second gap 9 through a syringe, with the oil layer height being the designed value h. Then, low-viscosity sealing oil is added to the first gap 7 through a syringe, with the oil layer height being the designed value L1. In this embodiment, dimethyl silicone oil with a viscosity of approximately 1 Pa·s can be used as the high-viscosity oil, and polybutene oil with a viscosity of approximately 0.5 Pa·s can be used as the low-viscosity oil. Thus, the rotor device is sealed, preventing air from entering the third gap 12 during high-speed rotation and causing deviations in the test results.

[0167] In one embodiment, refer to Figure 1 As shown, a dynamic sealing structure for a rotor device includes a rotor cover plate 1, a rotor outer cylinder 2, a rotor inner cylinder 3, a frame 4, and a rotor shaft 5. The rotor outer cylinder 2 has eight first through holes 18 evenly spaced circumferentially on its lower shoulder surface, and the frame 4 has eight internally threaded holes evenly spaced at corresponding positions. The rotor outer cylinder 2 is connected to the frame 4 with bolts, and a sealing ring is installed at the contact point to achieve a seal. The rotor inner cylinder 3 is mounted on the rotor shaft 5, which is mounted on the frame 4 via bearings. An inlet 13 is located below the bearings, allowing experimental fluid to enter a third gap 12. The rotor cover plate 1 has eight second through holes 20 evenly spaced circumferentially, corresponding to the eight first through holes 18 on the upper shoulder surface of the rotor outer cylinder. The rotor cover plate 1 and the rotor outer cylinder 2 are fastened together with bolts 10. A sealing ring groove 19 is also provided on the upper wall of the rotor outer cylinder for placing the sealing ring. When the rotor outer cylinder 2 and the rotor cover plate 1 are tightened with bolts, the sealing ring is compressed to achieve a seal. An annular sealing gap is formed between the rotor cover plate 1 and the upper edge wall of the rotor inner cylinder 3.

[0168] Reference Figure 3 and Figure 4As shown, the rotor cover plate 1 is a rotating structure with eight second through holes 20 evenly spaced circumferentially along its edge for mounting bolts. The center of the rotor cover plate 1 is hollow, and its inner wall has a raised annular wall surface in the middle, serving as an annular partition 8 to divide the gap formed between the rotor cover plate 1 and the upper edge 6 of the rotor inner cylinder into two parts. The inner annular surface of the annular partition 8 is coated with a superhydrophobic coating 15. The superhydrophobic coating 15 is also coated on the opposing solid wall surfaces of the annular partition 8 and the upper edge 6 of the rotor inner cylinder, as well as on the opposing solid wall surfaces of the rotor cover plate 1 and the large-diameter section of the two-section stepped shaft. The upper surface of the rotor cover plate 1 is provided with an annular shielding surface, the inner radius of which is smaller than the outer diameter of the upper edge 6 of the rotor inner cylinder, to cover the opening of the top sealing cavity formed by the rotor cover plate 1 and the upper edge 6 of the rotor inner cylinder, preventing oil from overflowing from the gap when the rotor inner cylinder 3 rotates at high speed.

[0169] Reference Figure 6 As shown, the rotor outer cylinder 2 is a hollow cylinder made of plexiglass, with an inner diameter larger than the outer diameter of the rotor inner cylinder 3. A third gap 12 is formed between the rotor outer cylinder 2 and the rotor inner cylinder 3 for holding the experimental fluid. Eight first through holes 18 are evenly distributed circumferentially on the upper shoulder surface of the rotor outer cylinder 2, and a sealing ring groove 19 is provided on the upper wall surface of the cylinder. Eight first through holes 18 are also evenly distributed circumferentially on the lower shoulder surface of the rotor outer cylinder, and a sealing ring groove is provided, with a sealing ring installed at the connection point with the frame.

[0170] Reference Figure 2 As shown, the rotor inner cylinder 3 is a cylindrical structure, fixedly mounted on the rotor shaft 5. The upper end of the rotor inner cylinder 3 is provided with an upper edge 6, the radius of which is smaller than the radius of the rotor inner cylinder body, for lightweight design. The upper edge 6 is a thin-walled annular structure. The stepped surfaces of the two-section stepped shaft, the upper edge 6 of the rotor inner cylinder, the inner wall of the rotor cover plate 1, and the lower surface of the annular partition 8 form a second gap 9. Simultaneously, a superhydrophobic coating 15 is sprayed onto the opposing solid wall surfaces of the annular partition 8 and the upper edge 6 of the rotor inner cylinder, as well as the opposing solid wall surfaces of the rotor cover plate 1 and the large-diameter section of the two-section stepped shaft.

[0171] One end of the rotor shaft 5 is connected to the frame 4 via a bearing, and the other end is fixedly connected to the rotor inner cylinder 3, thereby driving the rotor inner cylinder 3 to rotate.

[0172] The specific steps of the design method for the dynamic sealing structure using a rotor device proposed in this embodiment are as follows:

[0173] Step 1. Determine the dimensions of the inner and outer cylinders of the rotor assembly:

[0174] Based on the Reynolds number Re, torque T0 measurement range, and measurement accuracy required by the predetermined test, the outer radius of the rotor inner cylinder in this embodiment is determined. R 1. Inner cylinder height H, rotor outer cylinder inner radius is R 2. The formula for calculating the Reynolds number is:

[0175]

[0176] Where ζ represents the rotor angular velocity, in rad / s; d represents the width of the gap between the inner and outer cylinders of the rotor, d= R 2- R 1. The unit is meters (m). The kinetic viscosity of the fluid within the gap is expressed in m. 2 / s.

[0177] This embodiment is designed for high Reynolds number and high speed operating conditions, requiring a Reynolds number of 1.0 × 10⁻⁶. 5 The maximum speed reaches 800 r / min. R 1 / R 2 = 0.9. Rotor inner cylinder height H = 2 R 1. In summary, the parameters in this embodiment are defined as follows: R 1 = 108 mm R 2=120mm, H=216mm.

[0178] Step 2. Determine the torque between the concentric cylinders of the rotor assembly. T 0:

[0179] Establish the inner cylinder radius as R 1 = 108mm, outer cylinder radius is R A concentric cylindrical rotor model with a diameter of 120mm (H=216mm) and an inner and outer cylinder height of H=120mm was used. The flow field region was meshed using structured hexahedral meshing with ICEM, a method that reduces the number of elements and speeds up the solution process. The entire region was defined as a fluid, with water as the fluid medium. The boundary conditions were: the inner wall of the outer cylinder was set as a stationary wall, while the outer wall of the inner cylinder rotated at a given speed. Steady-state simulation of the coaxial flow field between the inner and outer cylinders was performed using Fluent software, employing a pressure-based steady-state solver and the SST k-ω model, which more accurately captures the wall simulation results. Finally, the frictional drag torque on the rotor surface at different speeds was obtained. T 0.

[0180] Step 3. Determine the torque introduced by the sealing structure:

[0181] (I) Calculate the contribution of the filling oil in the first gap 7 to the torque:

[0182] The first gap can be considered as a small coaxial rotor structure, in which the sealing oil generates a resistance torque on the rotor. T 1. Calculate according to the following formula:

[0183]

[0184] in,R 11 This indicates the outer radius along the upper wall of the rotor inner cylinder. R 12 This indicates the radius of the inner hole of the rotor cover plate. L 1 indicates the height of the sealing oil in the first gap. This indicates the rotational speed of the inner cylinder of the rotor, expressed in r / min. η 1 indicates the viscosity of the sealing oil in the first gap, in Pa·s. Polybutene with a viscosity of 0.5 Pa·s and a density of 0.83-0.91 g / cm³ is used as the sealing oil in the first gap. 3 Its density is less than that of water.

[0185] (II) Calculate the contribution of the filling oil in the second gap 9 to the torque:

[0186] The second gap can be viewed as a hollow disk structure that shears fluid motion; the sealing oil inside generates a resistance torque on the rotor. T 2. Calculate according to the following formula:

[0187]

[0188] in, R 21 Indicates the outer radius of the large-diameter section of the two-section stepped shaft, and h represents the height of the sealing oil in the second clearance. η The value 2 indicates the viscosity of the sealing oil in the second gap, expressed in Pa·s. Dimethyl silicone oil with a viscosity of 1 Pa·s and a density of 0.91-0.98 g / cm³ is used as the sealing oil in the second gap. 3 It is also less dense than water. Considering the fluctuations during high-speed rotor rotation, the radius of the rotor cover plate's inner hole is set to differ from the radius of the larger diameter section of the two-section stepped shaft by 1 mm, i.e. R 12 - R 21 =1mm. To minimize the impact of the sealing structure on the test results, the torque introduced by the sealing structure should be as small as possible, typically requiring... T 0 > 50 T 3, of which T 3= T 1+ T 2.

[0189] Step 4. Determine the dimensions of the sealing structure based on the torque relationship:

[0190]

[0191] Simplifying, we get:

[0192]

[0193] When the oil seal heightL When 1 and h are too high, excessive torque will be introduced, affecting the experimental results; when the height is too high... L When both 1 and h are too low, the amount of sealing oil in the gap is small, which can cause oil splashing during high-speed rotation, affecting the sealing effect. Considering the ease of adding oil and the requirements for sealing in actual operation, h is set to 15mm. L 1 = 5mm. For R 11 and R 12 The range is generally in the range of 1 / 6. R 1 to 1 / 2 R 1. Furthermore, a superhydrophobic coating needs to be applied between the two, and sealing oil needs to be added; therefore, the constraint conditions are met. R 12 - R 11 >2mm. This embodiment determines... R 11 Fixed at 20mm, set R 12 It is 25mm, therefore R 21 It is 24mm.

[0194] At rotor speeds of 100, 200, 300, 400, 500, 600, 700, and 800 r / min, the contribution of the sealing oil in the first and second gaps to the rotor torque is as follows: T 3= T 1+ T The values ​​of 2 are 0.000553914, 0.001107829, 0.001661743, 0.002215657, 0.002769572, 0.003323486, 0.0038774, and 0.004431315 N·m, respectively, which meet the above requirements.

[0195] Step 5: Add the experimental fluid into the rotor gap.

[0196] In this embodiment, the experimental fluid is pure water. The pure water is pumped through the inlet 13 directly below the rotor to the third gap 12 of the rotor via a diaphragm pump. The pure water in the rotor gap is observed. When the liquid level is flush with the lower interface of the rotor cover plate 1, the valve of the diaphragm pump is closed, and the diaphragm pump stops pumping pure water.

[0197] Step 6, add sealing oil to seal:

[0198] First, dimethyl silicone oil 16 is added to the second gap 9 through a syringe to a height of h = 15 mm. Then, polybutene 17 is added to the first gap 7 through a syringe to a height of h = 15 mm. L1 = 5mm.

[0199] This achieves the sealing of the rotor device, preventing gas from entering the third gap 12 during high-speed rotation and causing incorrect test results.

[0200] In this embodiment, the total torque of the rotor device filled with water and the total torque contributed by the filling sealing oil were tested and calculated at rotational speeds of 100, 200, 300, 400, 500, 600, 700, and 800 r / min, respectively. The results are as follows: Figure 7 As shown, the hollow circle symbol 21 represents the total torque contributed by the filling sealing oil, and the solid square symbol 22 represents the total torque when filled with water. It can be seen that the total torque is much greater than the total torque contributed by the sealing oil, and the torque contributed by the sealing oil is negligible in the total torque. Figure 8 The results show the change in experimental fluid torque over test time before and after applying this sealing method. Solid line 23 represents the torque test result using the method of this invention, while dashed line 24 represents the torque test result without this sealing method. It can be seen that without a suitable seal, the experimental fluid in the gap is thrown out during the long test, causing air to enter and reducing the torque value. However, with the sealing method described in this embodiment, the experimental fluid is confined within the gap, the torque is stable, and the sealing purpose is achieved. In other words, the method of this invention achieves dynamic sealing of the rotor device while introducing only a very small amount of additional torque. Furthermore, the method is simple and easy to assemble and disassemble the rotor.

[0201] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A dynamic sealing structure for a rotor device, the rotor device comprising an inner rotor cylinder and an outer rotor cylinder concentrically arranged and forming an annular gap between them to accommodate experimental fluid, and a rotor cover plate covering the top of the annular gap, characterized in that: The rotor inner cylinder extends axially into the inner hole of the rotor cover plate to form a two-section stepped shaft, wherein the larger diameter section is located between the smaller diameter section and the rotor inner cylinder, and the smaller diameter section constitutes the upper edge of the rotor inner cylinder; the dynamic sealing structure is located between the rotor cover plate and the two-section stepped shaft, including: A partition unit, disposed on the inner wall of the rotor cover plate, is used to divide the top sealing cavity formed by the rotor cover plate and the upper edge of the rotor inner cylinder into a first gap and a second gap arranged axially; the partition unit is an annular partition plate disposed on the inner wall of the rotor cover plate; the first gap is the space between the inner wall of the rotor cover plate located above the annular partition plate and the relatively solid wall surface of the upper edge of the rotor inner cylinder; the second gap is the space arranged axially between the lower surface of the annular partition plate and the stepped surface of the two-section stepped shaft; The layered sealing medium unit includes a first sealing oil filled in a first gap and a second sealing oil filled in a second gap with a viscosity higher than that of the first sealing oil. Both the first sealing oil and the second sealing oil are immiscible with the experimental fluid and have a density lower than that of the experimental fluid. The superhydrophobic interface unit is formed on the relative solid wall surface of the separator unit and the upper edge of the rotor inner cylinder, and on the relative solid wall surface of the rotor cover plate and the large diameter section, to retain an air film between the solid wall surface and the sealing medium to reduce the solid-liquid contact area. Among them, the first gap, the second gap, the superhydrophobic interface unit and the layered sealing medium unit work together to form a collaborative sealing system that prevents the experimental fluid from overflowing and the external gas from penetrating under dynamic rotation, while controlling the additional resistance torque introduced by the sealing to below a preset threshold. The outer radius of the smaller diameter segment of the two-section stepped shaft is: R 11 The inner radius of the rotor cover plate is R 12 The outer radius of the large-diameter section of the two-section stepped shaft is R 21 Satisfying Relationship: R 11 < R 21 < R 12 , R 11 and R 12 The value range is 1 / 6 R 1 to 1 / 2 R 1, and R 12 - R 11 >2mm, of which R 1 represents the outer radius of the rotor inner cylinder; The height of the sealing oil in the first gap L 1. Satisfies: 3mm≤ L 1≤10mm; The height h of the sealing oil in the second gap must satisfy: 5mm≤h≤15mm; The low-viscosity sealing oil used to fill the first gap has a viscosity of 0.1 Pa·s to 0.9 Pa·s, and the high-viscosity sealing oil used to fill the second gap has a viscosity of 1 Pa·s to 5 Pa·s.

2. The dynamic sealing structure of the rotor device according to claim 1, characterized in that: The rotor cover plate is an annular disk structure with an inner hole. The opening on its outer end face extends radially into the hole to form an annular shielding surface. The inner diameter of the annular shielding surface is smaller than the outer diameter of the upper edge of the rotor inner cylinder, which is used to cover the opening of the top sealing cavity. The outer edge of its inner end face extends radially outward to form a flange structure that is sealed and connected to the rotor outer cylinder.

3. The dynamic sealing structure of the rotor device according to claim 2, characterized in that: The superhydrophobic interface unit includes a superhydrophobic coating sprayed on the relative solid wall surfaces of the annular partition and the upper edge of the rotor inner cylinder, and on the relative solid wall surfaces of the rotor cover and the large-diameter section; an air film is formed in the annular cavity between the first sealing oil and the second sealing oil, and between the second sealing oil and the experimental fluid.

4. A design method for the dynamic sealing structure of the rotor device according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Determine the main torque reference: Based on the target experimental Reynolds number and rotational speed, determine the dimensions of the rotor inner cylinder and rotor outer cylinder; based on computational fluid dynamics, simulate and calculate the surface friction torque generated solely by the experimental fluid within the predetermined rotational speed range of the rotor device; the main torque is... T 0; Step 2: Establish the additional torque model and set constraints: Establish the additional resistance torque generated by the sealing oil in the first and second gaps. T 1 and T 2. Calculation model; setting the total additional torque that the dynamic sealing structure must meet. T 3= T 1+ T 2 is much smaller than the main torque T The constraint of 0, i.e. T 0> · T 3, of which, The preset coefficient is much greater than 1; Step 3: Collaborative Optimization of Sealing Structure Parameters: Under the constraints described, and prioritizing sealing reliability, the geometric dimensions of the first and second gaps, as well as the viscosity of the first and second sealing oils, are collaboratively and iteratively optimized to achieve the desired total additional torque. T 3 minimize; Step 4: Implement the sealing structure: Based on the optimized parameters, process a rotor cover plate with partition units, prepare superhydrophobic interface units on the specified wall surface, and sequentially fill with first sealing oil and second sealing oil of specified viscosity and height.

5. The design method according to claim 4, characterized in that: In step 2, the preset coefficient is... ≥50; Additional resistance torque T 1 and T 2. Calculate using the following formulas respectively: in, R 11 The outer radius of the smaller diameter segment of the two-section stepped shaft. R 12 Where is the inner radius of the rotor cover plate. R 21 The outer radius of the large-diameter section of the two-segment stepped shaft. L 1 represents the height of the sealing oil in the first gap. η 1 represents the viscosity of the sealing oil in the first gap; h represents the height of the sealing oil in the second gap. η 2 represents the viscosity of the sealing oil in the second gap; This represents the rotational speed of the rotor's inner cylinder.

6. The design method according to claim 5, characterized in that: In step 3, the specific process of collaborative iterative optimization includes: In satisfying R 12 - R 11 >2mm, 3mm≤ L Within the feasible engineering range of 1≤10mm, 5mm≤h≤15mm, adjustments can be made. R 11 , R 12 , L 1, h, η 1. η Combinations of values ​​for 2; For each set of parameters, calculate its performance within the target speed range. T 3. Maximum value; Filter out all that meet the requirements T 0min > ·max( T 3) parameter combinations, where T 0min This refers to the minimum main torque within the predetermined speed range; From the selected combinations, choose the one that makes max( T 3) The smallest parameter combination is taken as the final optimization result.

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