An squeeze film damper

Abstract

The present application relates to the technical field of aero-engine, in particular to an extrusion oil film damper, comprising at least one damping unit, the damping unit comprising: a damping cavity, the inside of which is suitable for filling damping liquid, and at least one side of the damping cavity is composed of an elastic film; a liquid inlet gap is arranged on one side of the damping cavity to make the damping cavity communicate with the outside; a flow hole is arranged through the elastic film, and the opening area of the liquid inlet gap is larger than that of the flow hole; under the action of external force, the damping liquid flows into the damping cavity, the elastic film is bulged, and part of the damping liquid is sprayed out of the flow hole to achieve the damping effect. The damping unit realizes the damping effect by cooperating with the damping liquid through the elastic film, the damping unit has simple structure and occupies little space, and when the damping effect and the stiffness are improved, the damping unit density can be increased to realize the improvement, without increasing or changing the structure of the extrusion oil film damper, so that the damping effect of the damper can be ensured.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and more specifically to a squeeze film damper. Background Technology

[0002] Squeeze film dampers are a type of support damping structure device commonly used in rotating machinery. By changing the overall stiffness and damping parameters of the support components, they improve the dynamic characteristics of the rotor system, thereby increasing the rotor system's ability to pass critical speeds, reducing vibration, and reducing the transmission of support forces.

[0003] For rotor systems, a certain degree of imbalance always exists due to processing and installation. During operation, this imbalance acts as an excitation force, causing rotor vibration at a frequency equal to the rotor speed. Extensive engineering practice has shown that for high-performance rotating machinery such as aero engines, the application of squeeze film dampers can effectively suppress rotor vibration and improve the performance, lifespan, structural integrity, and reliability of the rotating machinery. When the squeeze film damper is working, its journal precesses off-center without rotation. As the journal precesses, it approaches the outer ring of the damper at a certain point. The damping fluid within the gap compresses against each other, generating increased pressure. This increased pressure pushes the damping fluid outwards, causing flow. The faster the journal approaches the outer ring of the damper, the faster the damping fluid is displaced, and the higher the pressure within the gap, thus increasing the resistance experienced by the journal. The direction of movement of the journal of the squeeze oil film damper approaching the outer ring of the squeeze oil film damper is opposite to the direction of the oil film pressure on the journal of the squeeze oil film damper, so the squeezing action is a damping action.

[0004] In existing technologies, to further improve the structural parameters such as damping and stiffness of extrusion film dampers, it is often at the cost of increasing additional structural mass, occupying additional space, or increasing external energy consumption. While retaining the original structure of the extrusion film damper, methods such as appropriately reducing the oil film gap or increasing the eccentricity to enhance the extrusion effect to improve damping will lead to a non-linear increase in oil film stiffness along with the increase in oil film damping. Furthermore, the enhanced extrusion effect can also lead to the generation of steam cavitation, which actually reduces the vibration reduction effect. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the existing extrusion oil film damper reduces the vibration reduction effect when improving structural parameters such as damping and stiffness, thereby providing an extrusion oil film damper.

[0006] To solve the above-mentioned technical problems, the present invention provides a squeeze oil film damper, comprising at least one damping unit, wherein the damping unit comprises:

[0007] A damping cavity, the interior of which is adapted to be filled with damping fluid, wherein at least one side of the damping cavity is formed by an elastic membrane;

[0008] An inlet slit is provided on one side of the damping cavity to allow the damping cavity to communicate with the outside world;

[0009] A drain hole is provided through the elastic membrane, and the opening area of ​​the liquid inlet slit is larger than the opening area of ​​the drain hole;

[0010] Under the action of external force, the damping fluid flows into the damping cavity, causing the elastic membrane to bulge, and part of the damping fluid is ejected from the drain hole to achieve the damping effect.

[0011] Optionally, multiple damping units are provided, and the multiple damping units are arranged in an array in the same plane.

[0012] Optionally, it further includes: a damper outer ring, wherein a plurality of damping units are arranged in an array on the inner side surface of the damper outer ring.

[0013] Optionally, it also includes a damper journal, the outer ring of the damper being sleeved and mounted on the outside of the damper journal; a plurality of damping units are arranged in an array on the outer side surface of the damper journal.

[0014] Optionally, the damping unit is polygonal, and at least one side of the elastic membrane of the damping unit is movably disposed to form the liquid inlet slit, while the remaining sides of the elastic membrane of the damping unit are fixedly disposed.

[0015] Optionally, the vent holes of the plurality of damping units are arranged in an alternating orientation.

[0016] Optionally, the inlet slits of the plurality of damping units are arranged in an alternating orientation.

[0017] Optionally, the elastic membrane is made of metal.

[0018] Optionally, the elastic membrane is attached to the substrate layer, and the elastic membrane and the substrate layer enclose the damping cavity.

[0019] The technical solution of this invention has the following advantages:

[0020] 1. The extrusion oil film damper provided by the present invention includes at least one damping unit, the damping unit comprising: a damping cavity, the interior of which is adapted to be filled with damping fluid, at least one side of the damping cavity being formed by an elastic membrane; an inlet slit disposed on one side of the damping cavity to allow the damping cavity to communicate with the outside; and a drain hole penetrating the elastic membrane, the opening area of ​​the inlet slit being larger than the opening area of ​​the drain hole; under the action of external force, the damping fluid flows into the damping cavity, causing the elastic membrane to bulge, and part of the damping fluid is ejected from the drain hole to achieve a damping effect.

[0021] In operation, the damping fluid of the squeeze film damper flows from the inlet slit into the damping cavity, which is initially relaxed and at least one side is composed of an elastic diaphragm. Under inertia, the damping fluid impacts the elastic diaphragm, causing it to bulge slightly, and some of the damping fluid is ejected from the outlet. The damping unit achieves its damping effect through the interaction of the elastic diaphragm and the damping fluid. The damping unit has a simple structure and occupies very little space. Improvements in damping effect and stiffness can be achieved by increasing the density of the damping units without altering the overall structure of the squeeze film damper, thus ensuring its vibration reduction performance.

[0022] 2. The extrusion oil film damper provided by the present invention comprises multiple damping units arranged in an array on the same plane. By setting multiple damping units, the flow direction of the damping fluid flowing within the multiple damping units influences each other, thereby enhancing the damping effect. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the damping unit provided in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of the extrusion oil film damper provided in an embodiment of the present invention.

[0026] Figure 3 for Figure 2 A magnified view of a portion of point A in the middle.

[0027] Figure 4 for Figure 3 A magnified view of a section at point B, where the arrows indicate the direction of the damping fluid's movement.

[0028] Figure 5 This is a schematic diagram of the structure of the outer ring of the damper provided in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached diagram: 1. Damping cavity; 2. Elastic membrane; 3. Liquid inlet slit; 4. Drain hole; 5. Outer ring of the damper; 6. Damper journal. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Example

[0035] Figures 1 to 5 The image shows a squeeze film damper provided in this embodiment, including a damper outer ring 5, a damper journal 6, and multiple damping units. In other embodiments, the number of damping units can be set according to actual damping requirements, and a single damping unit can also be used.

[0036] The damping unit includes a damping cavity 1, an inlet slit 3, and a drain hole 4. The damping cavity 1 is suitable for being filled with damping fluid, and at least one side of the damping cavity 1 is composed of an elastic membrane 2. In this embodiment, the elastic membrane 2 is made of metal. In other embodiments, the elastic membrane 2 can also be a thin film of polymer material. The inlet slit 3 is located on one side of the damping cavity 1 to allow the damping cavity 1 to communicate with the outside. The drain hole 4 is disposed through the elastic membrane 2, and the opening area of ​​the inlet slit 3 is larger than the opening area of ​​the drain hole 4. Under the action of external force, the damping fluid flows into the damping cavity 1, causing the elastic membrane 2 to bulge, and part of the damping fluid is ejected from the drain hole 4 to achieve the damping effect.

[0037] Multiple damping units are arranged in an array on the same plane. Specifically, multiple damping units are arranged in an array on the inner surface of the outer ring 5 of the damper. The outer ring 5 of the damper is sleeved and installed outside the damper journal 6; multiple damping units are arranged in an array on the outer surface of the damper journal 6. The damping units are polygonal, and at least one side of the elastic diaphragm 2 of the damping unit is movably arranged to form a liquid inlet slit 3. The remaining sides of the elastic diaphragm 2 of the damping unit are fixedly welded to the inner surface of the outer ring 5 of the damper or the outer surface of the damper journal 6. The drainage holes 4 of the multiple damping units are arranged in an alternating orientation. The liquid inlet slits 3 of the multiple damping units are arranged in an alternating orientation.

[0038] Barnacles are marine organisms that attach themselves to natural reefs, docks, ship buoys, seawater pipelines, aquaculture facilities, and the bodies of organisms such as whales, sea turtles, and sea snakes. Their outer calcareous shells resemble miniature volcanoes, and they often form dense colonies.

[0039] This embodiment provides a biomimetic barnacle-inspired extrusion film damper, which is extremely lightweight, occupies almost no extra space, requires no external energy drive, is insensitive to impact and friction, is easy to repair, corrosion resistant, has a fast response, can work continuously, and has a flexible design scheme, making it suitable for further optimization of various types of extrusion film dampers.

[0040] The extrusion film damper implementation method provided in this embodiment employs metal thin film technology and micro-nano connection technology. Perforated flexible metal thin films are densely fixed as damping units on a solid metal wall surface that is in direct contact with the damping fluid. Additional damping effect is generated by the interaction between the damping fluid's inertial velocity and the damping units, appropriately increasing the overall oil film damping of the extrusion film damper. The increased damping effect depends on the parameters of the damping units, including their geometry, size, arrangement, thickness, material (elastic modulus), micro-nano connection location (weld), size of the inlet slit 3, and the number, diameter, and location of the outlet holes 4. Therefore, by rationally configuring the various parameters of the damping units, the extrusion film damper can provide high oil film damping and low oil film stiffness.

[0041] To describe the working principle of the damping unit, we take a relatively simple, approximately semi-circular single-outlet 4-damping unit as an example, such as... Figure 1As shown, its structure includes a metal elastic membrane 2, a weld, a liquid inlet 3, and a drain hole 4. The metal elastic membrane 2 is connected to the metal wall of the extrusion oil film damper by a weld, which is arc-shaped. The non-connected part is the liquid inlet 3, which deforms according to the stress state of the damping unit. The liquid inlet 3 is the inlet for the damping fluid to flow into the damping unit, and the drain hole 4 is the outlet for the damping fluid to be ejected from the damping unit. In the working state, the damping fluid flows into the originally relaxed damping unit from the liquid inlet 3. Under the action of inertia, the elastic membrane 2 of the damping unit bulges slightly, and a part of the damping fluid is ejected from the drain hole 4.

[0042] Since the space enclosed by each damping unit and its covering wall can be considered a miniature fluid channel, and the shape of this channel changes between a relaxed and a tensile state with variations in damping fluid pressure and velocity, micro-nano connection technology is not only used to connect the geometric edges of damping units to extrusion film dampers, but also to control the stiffness of the metal film (increasing or decreasing the connection area) and to create more complex, drag-increasing flow environments within the internal space of the damping unit.

[0043] The extrusion oil film damper provided in this embodiment is as follows: Figure 2 As shown, it includes an outer ring 5 of the damper, a journal 6 of the damper, damping fluid within the gap, and a damping unit. The squeeze-film damper consists of an outer ring 5, a journal 6, and damping fluid. A damping unit composed of an elastic membrane 2 is disposed on the inner side of the outer ring 5 and the outer side of the journal 6. The metal elastic membrane 2 forms a sandwich-like micro-element composed of the metal walls on both sides of the gap and the oil film within the gap, as shown... Figure 3 As shown. Before the extrusion film damper starts working, the damping unit is in a relaxed state. When the extrusion film damper works, the damping fluid is squeezed and flows circumferentially along the solid wall. Once the damping fluid and the wall generate relative motion, the damping unit immediately produces a damping effect. The damping fluid flows in from the inlet slit 3 of a damping unit, is decelerated and pressurized, and then ejected from the outlet slit 4, mixing with the damping fluid outside the damping unit, and flowing into an inlet slit 3 on the other side of the wall, causing that damping unit to start working. This cycle continues, continuously providing damping.

[0044] The principle of damping unit resistance increase, such as Figure 4As shown. Further, a "solid-liquid interface" micro-element is taken within the sandwich micro-element, where the oil film contacts a solid on one side. The damping fluid velocity decreases closer to the wall, and some of the damping fluid close to the solid wall flows into the inlet slit 3 formed between the damping unit and the wall. Since the damping unit only has a limited outlet, the drain hole 4, the damping unit is subjected to the impact pressure of the flowing damping fluid and enters a tensioned state, slightly bulging. The approximately wedge-shaped convergence region formed by the damping unit and the solid wall near the weld seam causes the damping fluid velocity to decrease and the pressure to increase, deflecting along the damping unit and the solid wall, and colliding with the subsequent incoming flow, forming an energy-dissipating vortex. Under the tension of the damping unit and the pressure of the incoming flow, the damping fluid with higher pressure inside the membrane will be ejected from the drain hole 4 and disturb the flow of the damping fluid outside the damping unit. In places where the oil film gap is small, it may even directly impact the damping unit and wall on the other side of the damping fluid, hindering the squeezing of the outer ring 5 of the squeezing oil film damper by the journal 6 of the squeezing oil film damper, which means hindering the squeezing effect of the oil film and inhibiting the formation of steam cavitation to a certain extent.

[0045] Because the circumferential flow of the damping fluid in the extrusion film damper is not only circumferential but also radial, the parameters and arrangement of the damping units need to be customized and optimized according to actual needs. After the design is completed, the substrate metal film is first processed to the required thickness, and then small damping units with vent holes 4 are processed using laser cutting and drilling technology. Then, micro-nano connection technology is used to weld all the damping units to the inner side of the outer ring 5 of the extrusion film damper and the surface of the damper journal 6, as well as other locations requiring increased resistance, according to the preset scheme. Figure 5 As shown. Each damping unit is pentagonal, and three pentagonal damping units work together to form a hexagonal damping unit cluster. Multiple hexagonal damping unit clusters are connected at their vertices or adjacent edges to form a ring-shaped hexagonal damping unit array. The ring-shaped hexagonal damping unit array is welded to the inner side of the outer ring 5 of the damper or welded to the outer surface of the damper journal 6. One side of the pentagonal damping unit facing outward from the hexagonal damping unit cluster is movably set as the liquid inlet slit 3, and the remaining sides of the pentagonal damping unit are fixedly connected to the outer ring 5 of the damper or the damper journal 6.

[0046] The precession of the journal 6 of the squeeze film damper is the source of damping provided by the damping unit, and the inertial velocity generated by the compression of the damping fluid is the direct driving force for the operation of the damping unit. The damping unit intercepts a portion of the flowing damping fluid near the wall, forming damping by dissipating the kinetic energy of the damping fluid and hindering the compression effect. The cluster of damping units increases the overall contact area between the damping fluid molecules and the metal, increasing viscous damping. The flow of damping fluid entering the damping unit is restricted, and some of the damping fluid further loses kinetic energy under the tension of the damping unit and the incoming flow behind, resulting in increased pressure. The area of ​​the inlet slit 3 of the damping unit is larger than the area of ​​the outlet vent 4. The damping fluid flowing into the damping unit from the inlet slit 3 and being ejected from the outlet vent 4 will produce a damping effect. The flow direction of the damping fluid ejected from the outlet vent 4 is not consistent with that of the damping fluid outside the damping unit. The damping fluids impact each other, dissipating kinetic energy and producing a damping effect. At locations with higher damping fluid flow rates and smaller oil film gaps, the damping fluid ejected from the vent hole 4 provides stronger resistance to the squeezing action, allowing the damping unit to reach its optimal working state.

[0047] The extrusion film damper provided in this embodiment is suitable for further optimizing various types of extrusion film dampers, providing them with additional damping, with minimal impact on the original design and high structural compatibility. The mass increment of the extrusion film damper caused by the attachment of the damping unit cluster is very small. The damping unit works within the oil film gap, occupying almost no extra space. The precession of the extrusion film damper journal 6 caused by the vibration of the rotor system is the driving force for the damping unit's operation, requiring no external energy drive. Due to the flexible metal membrane's certain deformation capacity, it can withstand the extrusion action. Due to the excellent properties of the metal material itself, minor collisions during the installation and removal of the extrusion film damper will not easily damage the damping unit. Even if some damping units are damaged due to improper operation, they can be reused simply by replacing the damaged parts. The chemically stable metal elastic membrane 2 can, to a certain extent, prevent cavitation from damaging the extrusion film damper. The inertial velocity generated by the extrusion of the damping fluid is the direct driving force for the damping unit's operation. As long as there is relative motion between the damping fluid and the wall surface, the damping unit will operate, with a fast response speed. The ring-shaped distribution of the damping unit cluster ensures that damping units are always operational when the journal 6 of the extrusion oil film damper precesses to any position. The drag-increasing effect of the extrusion oil film damper provided in this embodiment depends on various parameters of the damping units, their arrangement, and micro-nano connection technology, leaving considerable room for customization, optimization, and upgrading of the design scheme.

[0048] As an alternative implementation, if the size limitation of the extrusion oil film damper makes it inconvenient to implement micro-nano connection technology, a "double-layer film scheme" is adopted: a base metal film is prepared in advance as a substrate layer, the geometry of which matches the unfolded shape of the cylindrical surface such as the inner wall of the outer ring 5 of the extrusion oil film damper or the journal surface. Then, the processed damping unit is densely laid on the corresponding position of the base metal film and welded. After that, the whole thing is moved to the inner side of the outer ring 5 of the extrusion oil film damper or the journal surface and fixed. The elastic film 2 is connected to the metal substrate layer, and the elastic film 2 and the substrate layer enclose the damping cavity 1.

[0049] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A squeeze film damper, characterized in that, Includes at least one damping unit, said damping unit comprising: A damping cavity (1) is adapted to be filled with damping fluid, and at least one side of the damping cavity (1) is formed by an elastic membrane (2); The liquid inlet slit (3) is located on one side of the damping cavity (1) so that the damping cavity (1) can communicate with the outside world; The drain hole (4) is provided through the elastic membrane (2), and the opening area of ​​the liquid inlet slit (3) is larger than the opening area of ​​the drain hole (4); Under the action of external force, the damping fluid flows into the damping cavity (1), causing the elastic membrane (2) to bulge, and part of the damping fluid is sprayed out from the drain hole (4) to achieve the damping effect.

2. The extrusion oil film damper according to claim 1, characterized in that, The damping unit is provided in multiple ways, and the multiple damping units are arranged in an array in the same plane.

3. The extrusion oil film damper according to claim 2, characterized in that, Also includes: The damper outer ring (5) has multiple damping units arranged in an array on its inner side surface.

4. The extrusion oil film damper according to claim 3, characterized in that, It also includes a damper journal (6), the outer ring (5) of the damper is sleeved and installed outside the damper journal (6); a plurality of damping units are arranged in an array on the outer surface of the damper journal (6).

5. The extrusion oil film damper according to claim 3, characterized in that, The damping unit is polygonal, and at least one side of the elastic membrane (2) of the damping unit is movably arranged to form the liquid inlet slit (3), while the remaining sides of the elastic membrane (2) of the damping unit are fixed.

6. The extrusion film damper according to any one of claims 2 to 3, characterized in that, The vent holes (4) of the multiple damping units are arranged in an alternating orientation.

7. The extrusion oil film damper according to any one of claims 2 to 3, characterized in that, The inlet slits (3) of the multiple damping units are arranged in an alternating orientation.

8. The extrusion oil film damper according to any one of claims 1 to 3, characterized in that, The elastic membrane (2) is made of metal.

9. The extrusion oil film damper according to any one of claims 1 to 3, characterized in that, The elastic membrane (2) is connected to the substrate layer, and the elastic membrane (2) and the substrate layer enclose the damping cavity (1).

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