A floating elastic foil sealing structure with flow-induced separation

Abstract

The present invention discloses a flow-induced separation floating elastic foil sealing structure, comprising a stator assembly and a rotor assembly, wherein the stator assembly comprises a sealing cavity, an elastic sealing mechanism concentrically mounted in the sealing cavity, and a sealing support detachably connected to the high-pressure end of the sealing cavity; the rotor assembly is eccentrically mounted in the sealing cavity, a gap is provided between the rotor assembly and the elastic sealing mechanism, and a dynamic pressure groove is provided on the rotor assembly or the stator assembly. The present invention is used to solve the problem of poor tolerance and insufficient applicability of the rigid floating ring applied to the floating sealing structure in the aerospace field in the prior art, so as to ensure the reliability of high-parameter operation under gas phase and oil-gas two-phase lubrication conditions.

Description

Technical Field

[0001] The invention relates to the field of floating ring seals, and in particular to a flow-induced separation floating elastic foil seal structure. Background Art

[0002] Floating elastic foil seals have great tolerance to radial displacement of the sealing shaft, and therefore have good application prospects in rocket turbo pumps and aero-engine shaft sealing assemblies.

[0003] However, during the operation of an aircraft, slight changes in the pitch angle, yaw angle, and roll angle of the aircraft can induce instability. At the same time, as lubrication methods such as oil mist and oil gas are gradually applied to high-speed and high-temperature extreme environmental conditions, the flow form of different phases of the sealing medium coexisting is more susceptible to random uncertainty excitation caused by environmental factors and its own structure, resulting in seal failure, reduced mechanical work efficiency, and affecting the operation of the entire machine. This is also one of the main factors in the existing technology that restricts the widespread application of floating elastic foil sealing technology in the field of aircraft turboshaft engines. Summary of the invention

[0004] The present invention provides a flow-induced separation floating elastic foil sealing structure to solve the problem that the floating elastic foil sealing technology in the prior art is difficult to be directly applied to the field of aircraft turboshaft engines, thereby achieving the purpose of improving the comprehensive performance of the floating sealing structure under two-phase lubrication operating conditions, improving dynamic stability, and improving sealing reliability under high-speed and high-temperature service environments.

[0005] The present invention is achieved through the following technical solutions:

[0006] A flow-induced separation floating elastic foil sealing structure comprises a stator assembly and a rotor assembly. The stator assembly comprises a sealing cavity, an elastic sealing mechanism concentrically installed in the sealing cavity, and a sealing support detachably connected to the high-pressure end of the sealing cavity; the rotor assembly is eccentrically installed in the sealing cavity, a gap is provided between the rotor assembly and the elastic sealing mechanism, and a dynamic pressure groove is provided on the rotor assembly or the stator assembly.

[0007] In the prior art, due to the poor stability of the aircraft body and the coexistence of multiple phases of sealing media, the floating elastic foil sealing technology is difficult to be directly applied to the field of aircraft turboshaft engines. For this reason, the present invention proposes a flow-induced separation floating elastic foil sealing structure. The structure uses a sealing cavity as the main structure of the stator assembly, and an elastic sealing mechanism is installed on the inner wall of the sealing cavity. The rotor assembly passes through the sealing cavity and is eccentrically installed. Inevitably, the rotor assembly is on the inner side of the elastic seal.

[0008] When the present application is applied to high-speed and high-temperature gas-phase and oil-gas two-phase lubrication shaft end seals in aircraft and other aircraft, high-pressure medium flows in from one end where the dynamic pressure groove is opened, and the stator assembly rotates. Under the dual effects of the convergent wedge effect brought about by the eccentric installation and the dynamic pressure wedge effect brought about by the fluid viscosity, a pressurized fluid film is formed, which ensures that a certain gap is always maintained between the rotor assembly and the elastic sealing mechanism, thereby realizing non-contact sealing.

[0009] Furthermore, the rotor assembly includes a rotating shaft and a sleeve sleeved outside the rotating shaft, wherein the sleeve and the rotating shaft are interference fit to ensure that the sleeve rotates together with the rotating shaft; and a plurality of dynamic pressure grooves are evenly distributed in annular shapes on the outer wall of the sleeve.

[0010] Furthermore, the dynamic pressure groove extends to the end face of the high-pressure end of the sleeve. Those skilled in the art should understand that in the sealing structure of the present application, one end is the high-pressure end and the other end is the low-pressure end along the axial direction. When working, the high-pressure medium needs to flow into the dynamic pressure groove from the high-pressure end. Therefore, the present solution extends the dynamic pressure groove to the end face of the high-pressure end of the sleeve, that is, the dynamic pressure groove is opened with the high-pressure end face of the sleeve as the starting point, so that the dynamic pressure groove is in an open state at the high-pressure end face of the sleeve, which is convenient for the rapid pumping of the high-pressure fluid.

[0011] Furthermore, the sealing support and the sealing chamber are connected by fastening bolts.

[0012] Furthermore, the elastic sealing mechanism includes an annular flat foil and a corrugated foil, the flat foil and the corrugated foil are in contact with each other, and the flat foil is located on the inner diameter side of the corrugated foil; that is, along the radial direction, the outer wall of the flat foil is in contact with the inner end of the corrugated foil, the corrugated foil is clamped between the flat foil and the sealing cavity, and Coulomb friction occurs between the corrugated foil, the flat foil and the sealing cavity.

[0013] Compared with the conventional pure gas phase sealing structure, in the oil-gas two-phase working condition faced by the present application, the physical parameters such as viscosity and density of the lubricating oil are greatly affected by temperature and pressure. The sealing device is affected by thermal loads or external interference, which will destroy the internal flow field and is not conducive to the formation of a stable fluid film. The present application overcomes the above defects through the following principles: due to the load on the surface of the flat foil and the Coulomb friction between the flat foil and the corrugated foil, the entire elastic sealing mechanism can slide from the fixed end to the free end, and at the same time, it can undergo slight deformation in the radial and circumferential directions, so as to perform real-time adaptive adjustment, thereby fully ensuring the stability of the seal, thereby overcoming the failure problem when the sealing medium is multi-phase coexisting.

[0014] Furthermore, the flat foil is provided with an extension portion extending in the outer diameter direction at the high-pressure end, and the extension portion is clamped between the sealing cavity and the sealing support. The extension portion is located at the high-pressure end and extends radially outward, so it can be equivalently understood as a flange structure. The extension portion is put in place before connecting the sealing cavity and the sealing support, so that after the sealing cavity and the sealing support are connected, the extension portion is stably pressed between the two. In this state, the flat foil is fixed at one end on the high-pressure side and free at one end on the low-pressure side, thereby fully ensuring the integrity of the sealing surface.

[0015] Furthermore, the corrugated foil is separated into N mutually independent lobes by N separation boundaries, and one end of each corrugated foil is fixedly connected to the flat foil as a fixed end; wherein N≥2.

[0016] Among them, the separation boundary is related to the motion law of fluid particles. After determining a separation boundary that coincides with the streamline at the maximum fluid pressure, the remaining separation boundaries are obtained through a periodic array method.

[0017] Since the corrugated foil is annular as a whole, N separation boundaries can separate it into N petals. For each petal, one end of the corrugated foil is fixedly connected to the flat foil, which is the fixed end, and the other end opposite to it is the free end of the corrugated foil of the petal. N can be adaptively selected according to the specific working conditions.

[0018] Furthermore, on each lobe of wave foil, a plurality of separation gaps are opened along the circumferential direction on the side away from the fixed end, one end of the separation gap extends to the separation boundary away from the fixed end and the other end is closed; on each lobe of wave foil, the long axis direction of the wave arch is parallel to the separation boundary of the lobe of wave foil.

[0019] In the present solution, for each lobe of corrugated foil, a number of separation gaps are opened from the free end, and each separation gap is opened in the circumferential direction, and the separation gap does not completely penetrate the single lobe of corrugated foil, so that each lobe of corrugated foil still maintains the overall structure at the fixed end, but is divided into a number of small comb-like strips through a number of separation gaps. This arrangement can provide more flow channels for the fluid, significantly improve the heat dissipation efficiency, and prevent the foil from unnecessary deformation under large temperature fluctuations, thereby better adapting to the extremely high temperature operating environment of the turboshaft engine of an aircraft.

[0020] In addition, as is common knowledge in the art, the wave foil has an arc-shaped wave arch, and the wave arch has a major axis and a minor axis. The present solution stipulates that the major axis direction of the wave arch is parallel to the separation boundary of the flap wave foil, so that the arches that are prone to deformation are distributed along the streamline direction, making the deformation of the elastic sealing mechanism more uniform, and thus the flow field more stable.

[0021] This application provides the following two methods to determine the separation boundary.

[0022] Method 1:

[0023] Step 1: Based on the complete and non-separated wave foil, a dynamic pressure lubrication model of the floating elastic foil air film seal structure is established to obtain the flow field pressure control equation:

[0024]

[0025] Where r is the outer radius of the rotating axis, p is the air film pressure, h is the air film thickness, μ is the medium viscosity, z is the axial coordinate, θ is the circumferential coordinate, and ω is the rotation speed;

[0026] Step 2: Obtain the air film thickness control equation based on the dynamic pressure lubrication model:

[0027]

[0028]

[0029] Where h0 is the average air film thickness, h g is the depth of the dynamic pressure groove, ε is the eccentricity, k b is the stiffness of the wave foil, k p is the flat foil stiffness, p o is the pressure on the low pressure side, E b is the elastic modulus of the wave foil, E p is the elastic modulus of the flat foil, t b is the thickness of the foil, t p is the thickness of the flat foil, Ф is the angle of the corrugated foil, l is half the chord length of the corrugated foil, s is the pitch of the corrugated foil, and J is the friction factor μ f and the function of the angle Φ between the wave foil and the wave foil, ν b is the Poisson's ratio of the wave foil, ν p is the Poisson's ratio of the flat foil, d p is the bending stiffness of the flat foil, and x is the coordinate in the circumferential direction;

[0030] Step 3: Input structural parameters, working condition parameters, and mechanical performance parameters, couple and solve the flow field pressure control equation and the air film thickness control equation, and calculate the pressure distribution and thickness distribution;

[0031] Step 4: Calculate the velocity v in the x, y, and z directions of any intermediate layer flow field using the following formula: x 、v y 、v z :

[0032] Where y is the radial coordinate;

[0033] Calculate v x and v y The angle α:

[0034] Step 5: Determine the cylindrical coordinates (θ max , z max ), and the angle β between the x-direction velocity and the y-direction velocity at the maximum pressure;

[0035] Step 6: In one cycle, calculate the watershed to meet , connect the points, and obtain the mathematical expression of the separation boundary in the cylindrical coordinate system; where err is the judgment error.

[0036] Method 2:

[0037] Step A, establishing a solid domain model of a floating elastic foil sealing structure, determining a constraint relationship; calculating the flow field distribution when the sealing surface is not deformed;

[0038] Step B, transferring the calculation results of the fluid domain to the flat foil surface, completing the calculation of the sealing surface shape variable, and transferring the calculation results of the solid domain to the fluid domain, recalculating the flow field parameters after updating the air film thickness, and repeating the cycle until the calculation results of the solid domain and the fluid domain meet the convergence conditions and obtain a stable air film pressure distribution;

[0039] Step C, selecting multiple groups of streamlines or flow velocity vectors passing near the maximum pressure point;

[0040] Step D: According to the obtained streamline or velocity vector, based on image processing and analytical method, a mathematical expression of the separation boundary in the cylindrical coordinate system is obtained.

[0041] Among them, the advantage of method one is that the modeling amount is small, and it can perform accurate calculations for different working conditions and structural parameters, which is conducive to the full matching optimization of different structures and working conditions; the advantage of method two is that it can more accurately describe the interaction between contact elements (bump foil and flat foil, bump foil and sealing cavity), which is conducive to the behavior prediction and performance evaluation of specific structures and working parameters.

[0042] It should be noted that the above two flow-induced separation methods for wave foils can both play the role of pressurization, consumption reduction, heat dissipation and flow stabilization, mainly including:

[0043] (1) The direction from the free end of the foil to the fixed end is consistent with the direction of fluid rotation, that is, the rotor system drives the fluid film to rotate toward the free end of the foil. For each cycle of the flow field, a larger deformation is easily formed at the free end of the foil. On the contrary, the deformation at the fixed end of the foil is smaller, which increases the circumferential wedge degree of the flow field. The secondary wedge effect brought about by this flow-induced separation method can effectively enhance the buoyancy and has better dynamic performance.

[0044] (2) The flow-induced separation mode of the wave foil makes the streamline and the flow surface fit as closely as possible, which can effectively limit the range of the boundary layer. It can prevent the thickening or detachment of the boundary layer of the flow surface, and prevent the fluid protons from intersecting and colliding with the flow surface, thereby reducing or weakening the sudden stagnation or rapid acceleration in the local flow domain. This flow-guiding effect allows the fluid film to maintain the main flow trend, and the higher the rotation speed of the rotor system in the sealing device, the more obvious the effect.

[0045] (3) The flow channel expands after the fluid flows into the dynamic pressure groove, and contracts after the fluid flows out of the dynamic pressure groove. Due to the Rayleigh step effect, eddy currents or retention are likely to occur in the transition area of ​​the dynamic pressure groove. However, the present application suppresses the vortex scale in the transition area through the wave foil flow-induced separation method, and the changes in the flow parameters such as flow field pressure and temperature are more uniform and regular, thereby avoiding the phenomenon of eddy currents or retention of the fluid in the transition area of ​​the dynamic pressure groove.

[0046] (4) Due to the eccentricity of the rotor assembly, the thinnest air film corresponds to the high shear stress area, and compared with simple single-phase lubrication, the multiphase lubrication condition faced by this application will produce more internal friction power consumption. Through the wave foil flow-induced separation method, the velocity vector of the mixed medium can be made tangent to the flow surface, thereby reducing friction resistance and energy consumption, thereby improving sealing efficiency.

[0047] It should also be noted that when the present application is used in practice, different operating conditions can be matched by selecting different numbers of corrugated foil petals and dynamic pressure groove types. The present application does not make any limitation thereto, and any dynamic pressure groove type that can produce a dynamic pressure effect in the prior art can be applied to the present application.

[0048] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0049] 1. The present invention discloses a flow-induced separation floating elastic foil sealing structure, which is applied to high-speed and high-temperature gas-phase and oil-gas two-phase lubrication shaft end sealing of aircraft, etc. When the high-pressure medium flows in from one end where the dynamic pressure groove is opened, the stator assembly rotates, and a pressurized fluid film is formed under the dual effects of the convergence wedge effect brought by the eccentric installation and the dynamic pressure wedge effect brought by the fluid viscosity, so that a certain gap is always maintained between the rotor assembly and the elastic sealing mechanism, thereby realizing non-contact sealing; therefore, the present application can provide a sealing structure with good high-speed stability, a wide temperature application range, and a strong self-regulation capability, which is of great significance to the research and development of aircraft engines.

[0050] 2. The present invention provides a flow-induced separation floating elastic foil sealing structure, which can perform real-time adaptive adjustment under the working condition of oil and gas two-phase sealing medium, so as to fully ensure the stability of the seal, thereby overcoming the failure problem when the sealing medium is multi-phase coexisting.

[0051] 3. The present invention provides a floating elastic foil sealing structure with flow-induced separation. Through flow-induced separation of the wave foil, the direction from the free end of the wave foil to the fixed end is consistent with the direction of fluid rotation, that is, the rotor system drives the fluid film to rotate toward the free end of the wave foil. For each cycle of the flow field, a larger deformation is easily formed at the free end of the wave foil. On the contrary, the deformation at the fixed end of the wave foil is smaller, which increases the circumferential wedge degree of the flow field. The secondary wedge effect brought about by this flow-induced separation method can effectively enhance the buoyancy and has better dynamic performance.

[0052] 4. The present invention provides a floating elastic foil sealing structure with flow-induced separation. By flow-induced separation of the wave foil, the streamlines and the flow surface are made to fit as closely as possible, which can effectively limit the range of the boundary layer. It can prevent the thickening or detachment of the boundary layer of the flow surface, and prevent the intersection and collision of the fluid protons with the flow surface, thereby reducing or weakening the sudden stagnation or rapid acceleration in the local flow domain. This flow-guiding effect enables the fluid film to maintain the main flow trend, and the higher the rotation speed of the rotor system in the sealing device, the more obvious the effect.

[0053] 5. The present invention provides a floating elastic foil sealing structure with flow-induced separation, which suppresses the vortex scale in the transition area of ​​the dynamic pressure groove by flow-induced separation of the wave foil, and makes the changes of airflow parameters such as flow field pressure and temperature more uniform and regular, thereby avoiding the phenomenon of eddy current or retention of the fluid in the transition area of ​​the dynamic pressure groove.

[0054] 6. The present invention provides a floating elastic foil sealing structure with flow-induced separation. Through flow-induced separation of the wave foil, the velocity vector of the mixed medium is made tangent to the flow surface, thereby reducing friction resistance, lowering energy consumption, and thus improving sealing efficiency.

[0055] 7. The present invention provides a flow-induced separation floating elastic foil sealing structure, which divides each flap foil again through a plurality of separation gaps, can provide more flow channels for the fluid, significantly improve the heat dissipation efficiency, and prevent the foil from unnecessary deformation under large temperature fluctuations, thereby better adapting to the extremely high temperature operating environment of the turboshaft engine of aircraft aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0057] Figure 1 is a cross-sectional view of a specific embodiment of the present invention;

[0058] Figure 2 It is a schematic diagram of a partially cutaway structure of a specific embodiment of the present invention;

[0059] Figure 3An exploded view of a specific embodiment of the present invention;

[0060] Figure 4 It is a structural schematic diagram of a sealed cavity in a specific embodiment of the present invention;

[0061] Figure 5 It is a structural schematic diagram of a sealing support in a specific embodiment of the present invention;

[0062] Figure 6 It is a schematic diagram of the structure of a flat foil in a specific embodiment of the present invention;

[0063] Figure 7 It is a schematic diagram of the structure of the shaft sleeve in a specific embodiment of the present invention;

[0064] Figure 8 It is a schematic diagram of the structure of a corrugated foil in a specific embodiment of the present invention;

[0065] Fig. 9 It is a schematic diagram of pressure distribution and streamlines when determining the separation boundary in a specific embodiment of the present invention.

[0066] Marks and corresponding parts names in the attached drawings:

[0067] 1-sealing chamber, 11-positioning protrusion, 12-threaded positioning hole, 2-wavy foil, 21-separation gap, 22-welding point, 23-separation boundary, 3-flat foil, 31-extension section, 4-shaft sleeve, 41-dynamic pressure groove, 5-rotating shaft, 6-sealing support, 61-fixing through hole, 7-tightening bolt. DETAILED DESCRIPTION

[0068] In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the examples and drawings. The schematic embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0069] Embodiment 1:

[0070] like Figures 1 to 3A flow-induced separation floating elastic foil sealing structure shown includes a stator assembly and a rotor assembly. The stator assembly includes a sealing chamber 1, an elastic sealing mechanism concentrically installed in the sealing chamber 1, and a sealing support 6 detachably connected to the high-pressure end of the sealing chamber 1; the rotor assembly is eccentrically installed in the sealing chamber 1, and there is a gap between the rotor assembly and the elastic sealing mechanism, and also includes a dynamic pressure groove 41 arranged on the outer wall of the rotor assembly.

[0071] The rotor assembly includes a rotating shaft 5 and a sleeve 4 sleeved outside the rotating shaft 5, wherein the sleeve 4 and the rotating shaft 5 are interference fit; Figure 7 As shown, a plurality of dynamic pressure grooves 41 are annularly opened on the outer wall of the sleeve 4 , and the dynamic pressure grooves 41 extend to the end surface of the high-pressure end of the sleeve 4 .

[0072] The elastic sealing mechanism comprises an annular flat foil 3 and a corrugated foil 2 . The flat foil 3 and the corrugated foil 2 are in contact with each other, and the flat foil 3 is located on the inner diameter side of the corrugated foil 2 .

[0073] Flat foil 3 Figure 6 As shown, an extension portion 31 extending in the outer diameter direction is provided at the high-pressure end, and the extension portion 31 is clamped between the sealing cavity 1 and the sealing support 6 .

[0074] Preferably, in order to facilitate flanging processing of the extension portion 31, it can be set to a serrated structure.

[0075] In this embodiment, both the corrugated foil 2 and the flat foil 3 are concentric with the sealing cavity 1 .

[0076] Preferably, the sealing support 6 and the sealing chamber 1 are connected by a fixing bolt 7. Figure 4 and Figure 5 As shown, a fixing through hole 61 is provided on the sealing support, and a threaded positioning hole 12 is provided at the high-pressure end of the sealing chamber. The fixing bolt 7 passes through the fixing through hole 61 and is screwed into the threaded positioning hole 12 to realize a detachable connection between the sealing support and the sealing chamber; at the same time, by tightening the fixing bolt 7, the extension part can be fully squeezed and clamped to ensure the effective fixation of the high-pressure end of the flat foil to prevent axial and radial movement.

[0077] Preferably, Figure 4 As shown, a positioning protrusion 11 is provided inside the sealing cavity 1 for positioning the assembly of the elastic sealing mechanism, and the inner diameter of the flat foil 3 is the same as that of the positioning protrusion 11 .

[0078] Preferably, the thickness of the flat foil is 0.25-0.35 mm.

[0079] Preferably, the thickness of the corrugated foil is 0.25-0.35 mm.

[0080] Preferably, the dynamic pressure groove on the sleeve has a depth of 3 to 10 μm.

[0081] Preferably, the dynamic pressure groove can also be set on the surface of the flat foil. In this case, there is no need to set a slotted sleeve. That is, compared with the slotting forming method on the curved surface of the sleeve, the flat foil surface can be slotted and then curled into a ring, which is easier to process.

[0082] Embodiment 2:

[0083] A flow-induced separation floating elastic foil sealing structure, based on Example 1, the corrugated foil 2 is separated into multiple independent lobes by multiple separation boundaries 23, one end of each lobe of corrugated foil is used as a fixed end, welded to the flat foil 3 through a welding point 22, and the other end is a free end.

[0084] like Figure 8 As shown, on each lobe of wave foil, a plurality of separation gaps 21 are opened along the circumferential direction on the side away from the fixed end, one end of the separation gap 21 extends to the separation boundary 23 away from the fixed end, and the other end is closed; on each lobe of wave foil, the long axis direction of the wave arch is parallel to the separation boundary 23 of the lobe of wave foil.

[0085] When this embodiment is applied to high-speed and high-temperature gas-phase and oil-gas two-phase lubrication shaft end seals in aircraft and other aircraft, high-pressure medium flows in from one end where the dynamic pressure groove is set, and the sleeve rotates with the shaft. Under the dual effects of the convergence wedge effect brought by the eccentric installation and the dynamic pressure wedge effect brought by the fluid viscosity, a pressurized fluid film is formed, which makes the sleeve and the flat foil maintain a certain gap, thereby realizing non-contact sealing. In addition, due to the load on the surface of the flat foil and the Coulomb friction between the flat foil and the wave foil, the elastic foil can slide from the fixed end to the free end, and slightly deform in the radial direction and the circumferential direction, so as to perform real-time adaptive adjustment to ensure the stability of the seal. At the same time, the wave foil flow-induced separation method matched with it can play the role of pressurization, consumption reduction, heat dissipation, and flow stabilization.

[0086] Embodiment 3:

[0087] A floating elastic foil sealing structure with flow-induced separation, based on Example 2, the separation boundary 23 in this embodiment is determined by the following method:

[0088] Step 1: Obtain the flow field pressure control equation of the floating elastic foil air film seal

[0089] The wave foil and flat foil structure of the floating elastic foil seal is set to a complete non-separated state, and the remaining parameters are the same as the floating elastic foil seal structure with flow-induced separation in Example 2. By simplifying the NS equation and the continuity equation, the dynamic pressure lubrication model describing the floating elastic foil seal is obtained:

[0090]

[0091] Among them, r is the outer radius of the rotation axis, p is the air film pressure, h is the air film thickness, μ is the medium viscosity, z is the axial coordinate, θ is the circumferential coordinate, and ω is the rotation speed.

[0092] Step 2: Obtain the air film thickness control equation for the floating elastic foil seal

[0093]

[0094] in

[0095] Among them, h0 is the average air film thickness, h g is the depth of the dynamic pressure groove, ε is the eccentricity, k b is the stiffness of the wave foil, k p is the flat foil stiffness, p o is the pressure on the low pressure side, E b is the elastic modulus of the wave foil, E p is the elastic modulus of the flat foil, t b is the thickness of the foil, t p is the thickness of the flat foil, Ф is the angle of the corrugated foil, l is half the chord length of the corrugated foil, s is the pitch of the corrugated foil, and J is the friction factor μ f and the function of the angle Φ between the wave foil and the wave foil, ν b is the Poisson's ratio of the wave foil, ν p is the Poisson's ratio of the flat foil, d p is the bending stiffness of the flat foil, and x is the circumferential coordinate.

[0096] Step 3: Obtain the flow field pressure distribution of the floating elastic foil seal

[0097] Input structure parameters (h g ,s,t b ,t p ,.Φ,l), working parameters (p i , p o ,h0,ε,μ f ), mechanical properties parameters (E b 、E p , ν b , ν p ), couple the pressure equation and thickness equation to calculate the pressure distribution and thickness distribution.

[0098] Among them, p i is the high pressure side pressure.

[0099] Step 4: Obtain the velocity v in the x, y, and z directions of any intermediate layer flow field of the floating elastic foil seal x 、v y 、v z :

[0100] Where y is the radial coordinate;

[0101] At the same time, the formula Calculate the angle α between the x-direction velocity and the y-direction velocity.

[0102] Step 5: Determine the maximum pressure position and velocity angle

[0103] Determine the maximum pressure p max The cylindrical coordinates (θ max , z max ), where the angle between the x-direction velocity and the y-direction velocity is β.

[0104] Step 6: Determine the separation curve equation

[0105] Select a period and calculate the watershed to satisfy The coordinate points (θ, z) are connected to determine the separation curve equation y = y (θ, r B ,z), where err is the judgment error, r B is the outer radius of the foil.

[0106] After completing the above steps, the calculated separation curve is used to separate the whole-circle corrugated foil to form a three-petal separation structure. After separation, each petal of the corrugated foil is again separated into strips along the circumferential direction (i.e., the separation gap), and is welded to the flat foil through the corrugated arch at the fixed end to form a whole.

[0107] Embodiment 4:

[0108] A floating elastic foil sealing structure with flow-induced separation, based on Example 2, the separation boundary 23 in this embodiment is determined by the following method:

[0109] Step 1:

[0110] Using ANSYS APDL commercial software, the solid domain model of the floating elastic foil seal is established, and the constraints such as material parameters and contact are determined; ANSYS Fluent software is used to calculate the fluid domain when the sealing surface is not deformed;

[0111] Step 2:

[0112] The calculation results of the fluid domain are transferred to the flat foil surface to complete the calculation of the sealing surface deformation variable, and the calculation results of the solid domain are transferred to the fluid domain. After the air film thickness is updated, the flow field parameters are recalculated, and the cycle is repeated until the calculation results of the solid domain and the fluid domain meet the convergence conditions and a stable air film pressure distribution is obtained, such as Fig. 9 shown.

[0113] Step 3: Select multiple streamlines or velocity vectors passing near the point of maximum pressure;

[0114] Step 4: Use a combination of image processing and analytical methods to obtain the mathematical expression of the separation curve in the cylindrical coordinate system;

[0115] After completing the above steps, the calculated separation curve is used to separate the whole-circle corrugated foil to form a three-petal separation structure. After separation, each petal of the corrugated foil is again separated into strips along the circumferential direction (i.e., the separation gap), and is welded to the flat foil through the corrugated arch at the fixed end to form a whole.

[0116] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0117] It should be noted that, in this article, terms such as "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, the term "connected" used in this article can be directly connected or indirectly connected via other components without special explanation.

Claims

1. A flow-induced separation floating elastic foil sealing structure, comprising a stator assembly and a rotor assembly, characterized in that: The stator assembly comprises a sealing cavity (1), an elastic sealing mechanism concentrically mounted in the sealing cavity (1), and a sealing support (6) detachably connected to the high-pressure end of the sealing cavity (1); the rotor assembly is eccentrically mounted in the sealing cavity (1), a gap is provided between the rotor assembly and the elastic sealing mechanism, and further comprises a dynamic pressure groove (41) provided on the rotor assembly or the stator assembly; The elastic sealing mechanism comprises an annular flat foil (3) and a corrugated foil (2), the flat foil (3) and the corrugated foil (2) being in contact with each other, and the flat foil (3) is located on the inner diameter side of the corrugated foil (2); The corrugated foil (2) is separated into N mutually independent lobes by N separation boundaries (23), and one end of each corrugated foil is fixedly connected to the flat foil (3) as a fixed end; wherein N≥2; The separation boundary (23) is determined by the following method 1 or method 2: The method 1 comprises: Step 1: Based on the complete and non-separated wave foil, a dynamic pressure lubrication model of the floating elastic foil air film seal structure is established to obtain the flow field pressure control equation: Where r is the outer radius of the rotating axis, p is the air film pressure, h is the air film thickness, μ is the medium viscosity, z is the axial coordinate, θ is the circumferential angle coordinate, and ω is the rotation speed; Step 2: Obtain the air film thickness control equation based on the dynamic pressure lubrication model: Where h0 is the average air film thickness, h g is the depth of the dynamic pressure groove, ε is the eccentricity, k b is the stiffness of the wave foil, k p is the flat foil stiffness, p o is the low pressure side pressure, E b is the elastic modulus of the wave foil, E p is the elastic modulus of the flat foil, t b is the thickness of the foil, t p is the thickness of the flat foil, Ф is the angle of the corrugated foil, l is half the chord length of the corrugated foil, s is the pitch of the corrugated foil, and J is the friction factor μ f and the function of the angle Φ between the wave foil and the wave foil, ν b is the Poisson's ratio of the wave foil, ν p is the Poisson's ratio of the flat foil, d p is the bending stiffness of the flat foil, and x is the coordinate in the circumferential direction; Step 3: Input structural parameters, working condition parameters, and mechanical performance parameters, couple and solve the flow field pressure control equation and the air film thickness control equation, and calculate the pressure distribution and thickness distribution; Step 4: Calculate the velocity v in the x, y, and z directions of any intermediate layer flow field using the following formula: x 、v y 、v z : Where y is the radial coordinate; Calculate v x and v y The angle α: Step 5: Determine the cylindrical coordinates (θ max , z max ), and the angle β between the x-direction velocity and the y-direction velocity at the maximum pressure; Step 6: In one cycle, calculate the watershed that satisfies The coordinate points of the , connect the points, and get the mathematical expression of the separation boundary in the cylindrical coordinate system; where err is the judgment error; The second method comprises: Step A, establishing a solid domain model of a floating elastic foil sealing structure, determining a constraint relationship; calculating the flow field distribution when the sealing surface is not deformed; Step B, transferring the calculation results of the fluid domain to the flat foil surface, completing the calculation of the sealing surface shape variable, and transferring the calculation results of the solid domain to the fluid domain, recalculating the flow field parameters after updating the air film thickness, and repeating the cycle until the calculation results of the solid domain and the fluid domain meet the convergence conditions and obtain a stable air film pressure distribution; Step C, selecting multiple groups of streamlines or flow velocity vectors passing near the maximum pressure point; Step D: According to the obtained streamline or velocity vector, based on image processing and analytical method, a mathematical expression of the separation boundary in the cylindrical coordinate system is obtained.

2. A flow-induced separation floating elastic foil sealing structure according to claim 1, characterized in that: The rotor assembly comprises a rotating shaft (5), a shaft sleeve (4) sleeved outside the rotating shaft (5), the shaft sleeve (4) and the rotating shaft (5) being interference fit; and a plurality of dynamic pressure grooves (41) are evenly distributed in an annular manner on the outer wall of the shaft sleeve (4).

3. A flow-induced separation floating elastic foil sealing structure according to claim 2, characterized in that: The dynamic pressure groove (41) extends to the end surface of the high-pressure end of the shaft sleeve (4).

4. The floating elastic foil sealing structure with flow-induced separation according to claim 1, characterized in that: The sealing support (6) and the sealing chamber (1) are connected via a fixing bolt (7).

5. The floating elastic foil sealing structure with flow-induced separation according to claim 1, characterized in that: The flat foil (3) is provided with an extension portion (31) extending in the outer diameter direction at the high-pressure end, and the extension portion (31) is clamped between the sealing cavity (1) and the sealing support (6).

6. The floating elastic foil sealing structure with flow-induced separation according to claim 1, characterized in that: On each lobe of the wave foil, a plurality of separation gaps (21) are provided along the circumferential direction on a side away from the fixed end, one end of the separation gaps (21) extends to a separation boundary (23) away from the fixed end, and the other end is closed; on each lobe of the wave foil, the long axis direction of the wave arch is parallel to the separation boundary (23) of the lobe of the wave foil.

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