A diverging porous oil supply squeeze film damper for inhibiting vapor cavitation

Abstract

The present application relates to a kind of progressive porous oil supply extrusion oil film damper for inhibiting steam cavitation, comprising damper outer ring, damper inner ring and two sealing rings between them, oil film is formed between damper outer ring and inner ring, a plurality of circumferential arrangement oil supply holes are opened on damper outer ring, and the end of oil supply hole close to oil film is gradually increasing hole and gradually increases in diameter to oil film direction.The present application expands circumferential oil supply interval by setting multiple oil supply holes, can supplement lubricating oil in time, effectively inhibits steam cavitation;At the same time, gradually increasing oil supply hole changes oil supply direction, controls oil film pressure distribution, avoids damping due to too many oil supply holes to drop, but improves oil film damping.Simulation results show that, compared with traditional scheme, the present application can reduce oil vapor volume fraction by more than 85%, oil film damping is increased by nearly 20%, realizes the synergistic optimization of inhibiting steam cavitation and increasing damping.

Description

Technical Field

[0001] This invention relates to the field of extrusion oil film damper technology, specifically to a gradually expanding porous oil supply extrusion oil film damper that suppresses steam cavitation. Background Technology

[0002] Squeeze film dampers (SFDs) ensure the smooth operation of rotor systems due to their excellent passive vibration reduction performance. A well-designed SFD can significantly improve vibration reduction and reduce rotor amplitude. However, with the development of aero-engine technology, higher demands are placed on the vibration reduction performance of SFDs. To address this, by using expansion rings as end seals at both axial ends of the SFD, end leakage of lubricating oil is effectively suppressed, thus significantly improving oil film damping. However, as the precession speed of the journal increases, vapor cavitation occurs in expansion ring-sealed SFDs, affecting their damping performance. Furthermore, vapor cavitation can erode the damper surface, reducing the SFD's service life.

[0003] Suppressing steam cavitation in SFD (Surface Mount Die) systems with expansion ring seals typically involves increasing the oil supply pressure. However, in actual engine fuel supply systems, it's difficult to further implement a turbocharging system to provide high oil pressure. Therefore, increasing the number of oil supply holes is another way to suppress SFD steam cavitation. This increases the number of oil supply holes, creating additional lubricating oil flow paths on top of single-hole oil supply, thereby reducing the maximum pressure level of the SFD oil film. Furthermore, increasing the number of oil supply holes expands the circumferential oil supply range, ensuring timely replenishment of lubricating oil to the SFD interior, thus effectively suppressing SFD steam cavitation.

[0004] Therefore, in summary, the squeeze film damper has the following disadvantages during operation: 1. Single-hole oil supply expansion ring seal type SFD is prone to severe steam cavitation.

[0005] For SFDs with expansion ring end seals, using a single-hole oil supply results in a large oil film dynamic pressure range, making them prone to steam cavitation. Furthermore, the limited number of supply holes prevents timely replenishment of lubricating oil within the SFD, further exacerbating steam cavitation. In addition, when steam cavitation reaches a certain level, it reduces the damping performance of the SFD, which is detrimental to the safe and stable operation of the rotor system.

[0006] 2. It is difficult to further increase the fuel supply pressure in actual aircraft engines.

[0007] Increasing the oil supply pressure is an effective technical solution to suppress steam cavitation. However, in the engineering practice of aero engines, the squeeze film damper is supplied with lubricating oil by a branch of the engine lubricating oil system, making it difficult to further set up a pressurization system to provide a higher oil supply pressure.

[0008] 3. Too many oil supply holes will weaken the damping performance of SFD. Increasing the number of oil supply holes has a significant effect on suppressing steam cavitation in SFD and is better than increasing the oil supply pressure. However, too many oil supply holes will reduce the dynamic pressure range of the oil film, which in turn will lead to a decrease in the damping performance of SFD and make it impossible to achieve the synergistic optimization of increasing oil film damping and suppressing steam cavitation. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation.

[0010] This invention is achieved through the following technical solution: a gradually expanding multi-hole oil supply and extrusion film damper for suppressing steam cavitation is provided, comprising an outer ring of the damper, an inner ring of the damper, and two sealing expansion rings located between the outer ring and the inner ring of the damper. An oil film is formed between the outer ring and the inner ring of the damper, located between the two sealing expansion rings. The outer ring of the damper has a plurality of circumferentially arranged oil supply holes, and the end of the oil supply hole near the oil film is a gradually expanding hole with the diameter of the gradually expanding hole gradually increasing towards the oil film.

[0011] This design establishes additional lubricating oil flow paths by setting multiple oil supply holes, expanding the circumferential oil supply range and enabling timely replenishment of lubricating oil into the oil film, effectively suppressing the formation of vapor cavitation. Simultaneously, the ends of the oil supply holes are designed as gradually expanding orifices. This reduces lubricating oil leakage at the supply holes by decreasing the diameter of the upper bottom surface, thereby improving the sealing performance of the SFD and increasing the oil film pressure. Furthermore, it alters the angle between the oil supply direction and the flow direction of the lubricating oil within the oil film, hindering the flow of lubricating oil from the high-pressure zone to the low-pressure zone, delaying the pressure drop in the high-pressure zone and the pressure rise in the low-pressure zone, thus maintaining or even increasing oil film damping while suppressing cavitation.

[0012] As an optimization, the root diameter of the reaming orifice is d, and the end diameter is D, with the ratio of D to d being 1.3-2.5. This solution, by limiting the ratio of the end to root diameter of the reaming orifice to the range of 1.3-2.5, can achieve optimal sealing and pressure regulation while ensuring good oil supply capacity, avoiding increased lubricating oil leakage or processing difficulties caused by excessive flaring.

[0013] As an optimization, the expanding orifice is frustum-shaped with a taper of 1:2-1:5. This design sets the expanding orifice to a frustum shape and limits its taper, which helps to form a smooth oil flow path and makes the oil supply direction and oil film have a suitable tilt angle.

[0014] As an optimization, the outer ring of the inner ring of the damper has two expansion ring mounting grooves. This solution uses the expansion ring mounting grooves to position and fix the sealing expansion ring, ensuring that the expansion ring can stably fit against the outer ring of the damper during operation, forming a reliable end seal and reducing lubricating oil leakage.

[0015] As an optimization, the outer ring of the inner ring of the damper has an annular oil supply groove, and the oil supply hole is arranged opposite to the oil supply groove. The annular oil supply groove can temporarily store the lubricating oil from the oil supply hole and distribute it evenly throughout the interior of the damper, avoiding uneven local oil supply and further improving the stability of the oil film and the damping effect.

[0016] As an optimization, multiple oil supply holes are evenly distributed circumferentially. In this design, the circumferential distribution of oil supply holes allows lubricating oil to enter the oil film uniformly in the circumferential direction, avoiding uneven oil film pressure distribution caused by asymmetrical oil supply, thereby improving the overall working performance of the damper.

[0017] As an optimization, the number of oil supply holes is set to 3-7. Controlling the number of oil supply holes to 3-7 can achieve the best balance between suppressing steam cavitation and maintaining oil film damping, avoiding excessive damping reduction due to too many oil supply holes, while ensuring sufficient oil supply coverage.

[0018] As an optimization, the oil supply hole is located in the middle of the oil film. This allows the lubricating oil to enter from a region with relatively uniform oil film pressure, which is beneficial for rapid oil diffusion and pressure reconstruction, further improving the damper's response speed and vibration reduction effect.

[0019] The beneficial effects of this invention are as follows: This invention provides a gradually expanding multi-hole oil supply and compression oil film damper for suppressing steam cavitation. By increasing the number of oil supply holes and combining them with a gradually expanding oil supply hole structure, it achieves synergistic optimization of suppressing steam cavitation and improving oil film damping. On the one hand, multiple oil supply holes establish additional lubricating oil flow paths and expand the circumferential oil supply range, ensuring timely lubricating oil replenishment. On the other hand, the gradually expanding oil supply holes effectively avoid the damping reduction problem caused by traditional multi-hole oil supply by adjusting the oil film pressure distribution through changing the oil supply direction. Simultaneously, this invention also optimizes the direction of oil film force, increasing the proportion of the tangential force component and decreasing the proportion of the radial force component, further improving the vibration reduction effect. Furthermore, it can adapt to the existing oil supply conditions of aero-engines without the need for an additional pressurization system, demonstrating outstanding engineering practicality and broad application prospects. Attached Figure Description

[0020] Figure 1 This is a cross-sectional schematic diagram of the present invention; Figure 2 This is a partial enlarged view of the present invention; Figure 3 This is a schematic diagram of the expansion ring structure of the present invention; Figure 4This is a schematic diagram of the circumferential distribution of the gradually expanding oil supply holes of the present invention; Figure 5 This is a design flowchart of the present invention; Figure 6 A schematic diagram showing the distribution of oil supply holes for different extrusion oil film dampers; Figure 7 A schematic diagram showing the variation of oil film damping with precession frequency for different extrusion oil film dampers; Figure 8 A schematic diagram showing the variation of oil vapor volume fraction with precession frequency for different extrusion oil film dampers; Figure 9 This is a schematic diagram of the oil film force distribution of the extrusion oil film damper of the present invention; As shown in the figure: 1. Damper outer ring, 2. Damper inner ring, 3. Sealing expansion ring, 4. Oil supply hole, 5. Oil film, 6. Oil supply groove, 7. Bearing, 8. Rotor shaft, 9. Expansion ring mounting groove. Detailed Implementation

[0021] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0022] like Figures 1-9 As shown, the present invention discloses a gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation, comprising an outer ring 1, an inner ring 2, and two sealing expansion rings 3 located between the outer ring 1 and the inner ring 2. An oil film 5 is formed between the outer ring 1 and the inner ring 2, located between the two sealing expansion rings 3.

[0023] Bearing 7 is installed on the inner ring of the damper inner ring 2 to support the rotor shaft 8. The outer ring of the damper inner ring 2 has two expansion ring mounting grooves 9. Two sealing expansion rings 3 are respectively installed in the two expansion ring mounting grooves 9. In the SFD working state, the expansion rings reach the outside of the expansion ring mounting grooves 9 by the pressure of lubricating oil and tightly adhere to the outer ring 1 of the damper through their own elasticity, thereby achieving effective sealing at both ends of the damper's axial direction. The specific structural form of the expansion rings is as follows... Figure 3 As shown.

[0024] The inner ring 2 of the damper also has an annular oil supply groove 6 on its outer ring. The oil supply groove 6 is used to evenly transport and distribute the lubricating oil to the entire circumferential area inside the damper.

[0025] Multiple circumferentially distributed oil supply holes 4 are opened on the outer ring 1 of the damper, and the oil supply holes 4 are located at the axial center of the oil film 5 and are opposite to the oil supply groove 6. The oil supply holes 4 pass through the outer ring 1 of the damper radially.

[0026] The number of oil supply holes 4 is 3 to 7, such as Figure 4As shown, this embodiment uses five oil supply holes as an example for explanation. Figure 2 As shown, the end of the oil supply hole 4 near the oil film 5 is a gradually expanding hole. The diameter of the gradually expanding hole gradually increases towards the oil film 5. That is, the diameter d (root diameter) of the upper bottom surface of the oil supply hole 4 is smaller than the diameter D (end diameter) of the lower bottom surface, thus forming a variable diameter gradually expanding oil supply hole structure.

[0027] The ratio of the diameter D at the end of the gradually expanding hole to the diameter d at the root is 1.3 to 2.5, and the gradually expanding hole is frustum-shaped with a taper of 1:2 to 1:5.

[0028] Because the damper is supplied with lubricating oil by controlling the supply pressure, when the oil film pressure is higher than the supply pressure, the lubricating oil flows out through the supply port 4. Based on this characteristic, increasing the number of SFD supply ports creates additional lubricating oil flow paths, thereby reducing the dynamic pressure range of the oil film and expanding the circumferential supply range, thus suppressing the generation of vapor cavitation. However, an excessive number of supply ports can also reduce the oil film damping. At this time, the gradually expanding supply port 4 reduces the amount of lubricating oil leakage at the supply port by reducing the diameter of the upper bottom surface of the supply port, thereby improving the sealing performance of the SFD and increasing the oil film pressure of the SFD. In addition, for the gradually expanding supply port, its supply direction is at a certain angle to the oil film, which causes the supply direction to be opposite to the flow direction of the lubricating oil inside the oil film, hindering the flow of lubricating oil from the high-pressure area to the low-pressure area. This obstruction increases the difficulty of lubricating oil delivery to the low-pressure area, causing high-pressure lubricating oil to be unable to flow out of the high-pressure area in time, thus slowing down the drop in lubricating oil pressure in the high-pressure area. At the same time, the lubricating oil with higher pressure cannot flow into the low-pressure area in time, thus delaying the rise in lubricating oil pressure in the low-pressure area as well. In summary, by controlling the oil film pressure distribution through multiple gradually expanding oil supply holes, the aim is to increase oil film damping and suppress steam cavitation.

[0029] The design process of the progressively expanding porous oil supply SFD of the present invention is as follows: Figure 5 As shown. In practical engineering applications, the most reasonable optimization scheme can be selected by flexibly adjusting parameters such as the number of oil supply holes, the diameter ratio D / d of the involute hole, and the taper, according to the working conditions and performance requirements of the rotor system. This can achieve synergistic optimization of suppressing steam cavitation and increasing oil film damping, thereby improving the damping performance and operational stability of the SFD.

[0030] To verify the technical effectiveness of this invention, CFD numerical simulation models of three different SFDs were established for comparative experiments: single-hole oil supply SFD, five-hole oil supply SFD, and five-hole oil supply SFD using a gradually expanding oil supply orifice (i.e., the scheme of this invention). The distribution of the oil supply orifices in the different SFDs is as follows: Figure 6 As shown.

[0031] Numerical simulations were performed on all three SFDs under conditions of a precession frequency of 50–350 Hz and an eccentricity of 0.5. The results are as follows: Figure 7and Figure 8 As shown. By Figure 7 and Figure 8 Numerical simulation results show that, compared with traditional single-hole oil supply SFD and ordinary multi-hole oil supply SFD, the vapor cavitation phenomenon of the progressively expanding multi-hole oil supply SFD of this invention is significantly suppressed, and the problem of reduced oil film damping caused by too many oil supply holes is clearly avoided. Taking 250Hz as an example, compared with single-hole oil supply SFD, the oil vapor volume fraction of the traditional five-hole oil supply SFD is reduced from 16.20% to 1.50%, but the oil film damping is also reduced by 4.12%. In contrast, the oil vapor volume fraction of the progressively expanding multi-hole oil supply SFD is 3.15%, a reduction of 85.56%, and the oil film damping is increased by 19.17%. Compared with the traditional five-hole oil supply SFD, the damping increase reaches 24.29%.

[0032] Thanks to the regulating effect of increasing the number and type of oil supply holes on the oil film pressure distribution in SFD, the direction of the oil film force in the gradually expanding multi-hole oil supply SFD changes compared to the single-hole oil supply SFD. The proportion of the tangential force component increases while the proportion of the radial force component decreases. Figure 9 As shown, F1 is the oil film force of a single-hole oil supply SFD, and F2 is the oil film force of a gradually expanding multi-hole oil supply SFD.

[0033] Numerical simulation results verify that the gradually expanding multi-hole oil supply SFD retains the advantage of increasing the number of oil supply holes to suppress steam cavitation, and significantly increases oil film damping, thereby improving the damping performance and stability of the SFD, demonstrating the effectiveness and feasibility of this invention patent.

[0034] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation, comprising an outer ring (1), an inner ring (2), and two sealing expansion rings (3) located between the outer ring (1) and the inner ring (2), wherein an oil film (5) is formed between the two sealing expansion rings (3) between the outer ring (1) and the inner ring (2), characterized in that: The outer ring (1) of the damper has multiple circumferentially arranged oil supply holes (4). The end of the oil supply hole (4) near the oil film (5) is a gradually expanding hole, and the diameter of the gradually expanding hole gradually increases towards the oil film (5).

2. The gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation according to claim 1, characterized in that: The root diameter of the reaming hole is d, and the end diameter of the reaming hole is D. The ratio of D to d is 1.3-2.

5.

3. The gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation according to claim 1, characterized in that: The expanding hole is frustum-shaped with a taper of 1:2-1:

5.

4. The gradually expanding porous oil supply and extrusion film damper for suppressing steam cavitation according to claim 1, characterized in that: The inner ring (2) of the damper has two expansion ring mounting grooves (9) on its outer ring, and two sealing expansion rings (3) are respectively set in the two expansion ring mounting grooves (9).

5. The gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation according to claim 1, characterized in that: The inner ring (2) of the damper has an annular oil supply groove (6) on its outer ring, and the oil supply hole (4) is arranged opposite to the oil supply groove (6).

6. The gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation according to claim 1, characterized in that: Multiple oil supply holes (4) are evenly distributed circumferentially.

7. The gradually expanding porous oil supply extrusion film damper for suppressing vapor cavitation according to claim 1, characterized in that: The oil supply hole (4) is provided with 3-7 holes.

8. The gradually expanding porous oil supply extrusion film damper for suppressing steam cavitation according to claim 1, characterized in that: The oil supply hole (4) is located in the middle of the oil film (6).

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