Turbine machinery foil end face gas film sealing element under extreme working condition

Abstract

The invention relates to the technical field of sealing, and provides an extreme working condition turbomachinery foil end face gas film sealing element which comprises a ring base, a plurality of elastic supporting bodies are arranged above the ring base, a back plate is arranged above the elastic supporting bodies, a plurality of bump foil bottom plates are arranged above the back plate, and a plurality of bump foil bottom plates are arranged above the ring base. A plurality of bump foil assemblies are arranged above the bump foil piece bottom plate, a top plate assembly is arranged above the bump foil assemblies, a plurality of elastic flat strips are arranged above the top plate assembly, a plurality of flat foil pieces are arranged above the elastic flat strips, and sealing foil pieces are arranged on the inner diameter sides or the outer diameter sides of the flat foil pieces. According to the invention, the film pressure and the foil deformation distribution can be automatically adjusted when the film thickness is disturbed or the working condition is changed, and the failure problems of end face collision and abrasion, crashing, hot cracking and the like caused by insufficient vibration impact resistance, heat impact resistance and self-adaptive capability of the existing rigid end face seal are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, specifically to a gas film seal for the end face of a foil in turbine machinery operating under extreme conditions. Background Technology

[0002] Foil-face gas film seals are non-contact sealing devices based on a multi-layer flexible foil structure. They achieve efficient sealing by forming a micron-level gas film through elastic deformation. The core principle utilizes the synergistic effect of hydrodynamic pressure and elastic support: during high-speed rotation, the specific geometry of the foil surface guides the gas to form a wedge-shaped gap, generating hydrodynamic pressure to support the sealing end face. Simultaneously, the underlying elastic element provides multi-directional flexibility compensation, dynamically adjusting the gas film gap to adapt to fluctuations in operating conditions. These sealing devices are particularly suitable for extreme environments with wide temperature ranges, high speeds, high vibrations, and severe thermal gradients, such as high-speed, high-temperature turbine machinery like aero engines and gas turbines, as well as industrial equipment such as high-speed centrifugal compressors, turbine expanders, and turbochargers operating with high-temperature or low-temperature media. Compared to traditional sealing methods, their advantages lie in dynamically adjusting the gas film gap through elastic deformation, significantly improving adaptability, effectively controlling leakage, and breaking through the temperature or speed adaptation limits of existing technologies. The lightweight design and improved reliability directly drive performance upgrades for turbine machinery in extreme dynamic scenarios.

[0003] Chinese Patent Publication No. CN104913064B discloses a cantilevered foil end-face air film sealing structure, comprising a dynamic ring and a stationary ring for air film sealing; the sealing end face of at least one of the dynamic or stationary rings is a cantilevered foil end face, the cantilevered foil end face comprising a circular ring body, a foil made of elastic material, and a pin, the inner side of the ring body being raised to form a circular step, the upper surface of the circular step forming a sealing dam; a plurality of foils are laid end-to-end on the outside of the sealing dam. On the concave surface of the annular ring, the foil is fan-shaped and evenly distributed along the circumference. One end of the foil is fixed to the ring body, while the other end is free. The free end of the foil is suspended above the fixed end of the preceding foil. The upper surface of the free end is flush with the sealing dam plane and higher than the upper surface of the fixed end. The circumferential direction from the fixed end to the free end of the foil is consistent with the circumferential direction of the airflow. The foil is radially divided into several small pieces from the free end to the fixed end, with the inner pieces being wider than the outer pieces. The invention features good stability, low wear, long lifespan, high reliability, high temperature resistance, high speed resistance, and strong adaptability.

[0004] In existing technologies, end-face air film seals are prone to problems such as insufficient adaptability to extreme conditions and media leakage under high-speed and high-pressure differential conditions due to the limited self-adaptive ability of rigid sealing dams, or factors such as assembly gaps, uneven film thickness distribution, vibration and thermal deformation.

[0005] In summary, the present invention provides a gas film seal for the end face of a turbine foil under extreme operating conditions to solve the above-mentioned problems. Summary of the Invention

[0006] This invention provides a gas film seal for the end face of a foil in turbine machinery under extreme operating conditions. By using a sealing foil, and with the upper and lower top plates overlapping at the edges to cover the leakage gap that may occur at the flange end, the problem of easy media leakage in the prior art can be solved without sacrificing adaptive performance.

[0007] The specific technical solution of this invention is as follows: An extreme-condition turbine machinery foil end-face air film seal is characterized by comprising: a ring base, a plurality of elastic supports disposed above the ring base, a back plate disposed above the elastic supports, a plurality of corrugated foil base plates disposed above the back plates, a plurality of corrugated foil assemblies disposed above the corrugated foil assemblies, a top plate assembly disposed above the corrugated foil assemblies, a plurality of elastic flat strips disposed above the top plate assembly, a plurality of flat foils disposed above the elastic flat strips, and sealing foils disposed on the inner or outer diameter side of the flat foils.

[0008] In this invention, the ring base serves as the basic load-bearing component of the entire seal and is used to fix the elastic support. The grooves on the ring base form a clearance fit with the top plate assembly, which can meet the axial floating requirements of the top plate assembly. At the same time, through the interference fit with the pin, the U-shaped groove of the back plate restricts the circumferential rotation of the overall structure, ensuring the relative position stability of each component.

[0009] The elastic support is a flexible support component with millimeter-level large deformation capability. It can be made of corrugated foil, circumferentially distributed small springs, wave springs, or other equivalent elastic structures. When corrugated foil is used, its structure is similar to that of the upper and lower corrugated foil layers, and it achieves multi-directional compensation in the axial, radial, and circumferential directions through its own elastic deformation. When circumferentially distributed small springs or wave springs are used, the same compensation function can be achieved through the expansion and contraction deformation of the springs. Regardless of the structure used, the elastic support can buffer disturbances caused by vibration or displacement, and can cooperate with spacers (such as corrugated foil abutting against spacers, spring ends limiting spacers) to prevent sealing system failure due to excessive deformation.

[0010] Furthermore, the material of the elastic support can be a high-temperature alloy or a smart deformable material with temperature response characteristics (such as a temperature-controlled shape memory alloy): when a high-temperature alloy is used, it can meet the requirements of high temperature resistance and fatigue resistance under extreme working conditions; when a temperature-controlled shape memory alloy is used, it can compensate for the loss of preload caused by the degradation of material mechanical properties by adjusting its own deformation force when the temperature changes, which is especially suitable for stable operation in high-temperature environments such as aero engines.

[0011] The back plate is the middle connecting and load-bearing component. It is fixed to the corrugated foil base plate and corrugated foil assembly by spot welding at the top, and cooperates with the elastic support body at the bottom to transfer the load. The U-shaped groove on its outer edge cooperates with the pin to form a circumferential limiting structure to prevent relative circumferential rotation during high-speed rotation.

[0012] The corrugated foil base plate mainly serves to support and strengthen rigidity, directly supporting the upper corrugated foil assembly. It is connected to the corrugated foil and back plate by spot welding, so that the force of the corrugated foil assembly is evenly transferred to the back plate, avoiding unexpected deformation of the corrugated foil due to force concentration.

[0013] In the top plate assembly, the upper top plate is fixed with elastic flat strips, flat foils and sealing foils by spot welding. Its flanged structure design improves machinability, and the segmented design with cut outer edges can reduce thermal deformation stress. The lower top plate is installed in an overlapping manner with the upper top plate. The staggered stacking blocks the leakage gap that may be generated at the flange end, thereby improving leakage control performance.

[0014] The elastic flat strip is spot-welded to the flat foil along the rear edge. Its main function is to raise the horizontal area of ​​the flat foil, so that the sloping area and the horizontal area of ​​the flat foil form a wedge-shaped gap, creating conditions for the generation of hydrodynamic pressure effect.

[0015] The flat foil is divided into a gap area, a ramp area, and a horizontal area. It is spot-welded to the upper top plate through the gap area. Its core function is to generate a dynamic pressure effect. The principle is that when rotating at high speed, the wedge-shaped gap guides the gas to form a fluid dynamic pressure, which pushes the flat foil to separate from the mating surface, forming a load-bearing gas film to achieve non-contact sealing.

[0016] The sealing foil is spot-welded to the upper top plate along the circumference, mainly for sealing. By blocking the leakage path, it forms a multi-level leakage control barrier in conjunction with the overlapping design of the top plate components, thereby enhancing the overall sealing effect.

[0017] In a preferred embodiment, the flat foil includes a gap area, a ramp area, and a horizontal area, the elastic flat strip is disposed below the horizontal area, and the gap area is fixedly connected to the top plate assembly.

[0018] In a preferred embodiment, the top plate assembly includes an upper top plate and a lower top plate. The upper top plate is fixedly connected to an elastic flat strip, a flat foil, and a sealing foil. The lower top plate overlaps with the upper top plate.

[0019] In a preferred embodiment, the corrugated foil assembly includes at least one layer of corrugated foil, the corrugated foil of the corrugated foil assembly being fixedly connected to the lower top plate and to the corrugated foil bottom plate.

[0020] In this invention, the corrugated foil assembly is the core flexible support component. It can be set with one, two, three or more layers of corrugated foil according to the load and deformation requirements under extreme working conditions. Multi-directional flexibility compensation is achieved through elastic deformation to adapt to the dynamic changes in the thickness of the air film.

[0021] When the corrugated foil assembly is a single-layer corrugated foil sheet, one side of the corrugated foil sheet is fixedly connected to the top plate assembly (e.g., fixed by spot welding at the crest), and the other side is fixedly connected to the bottom plate of the corrugated foil sheet (e.g., fixed by spot welding at the trough). It independently undertakes the function of elastic support, and its deformation can directly respond to changes in working load.

[0022] When the corrugated foil assembly consists of two or more layers of corrugated foil, the layers of corrugated foil are stacked sequentially along the axial direction: the corrugated foil closest to the top plate assembly (upper corrugated foil) is fixedly connected to the top plate assembly, and the corrugated foil closest to the bottom plate (lower corrugated foil) is fixedly connected to the bottom plate. The corresponding positions of two adjacent layers of corrugated foil (such as troughs) are fixed by spot welding to form a support structure that deforms as a whole.

[0023] Furthermore, there is a preset difference of 10μm to 50μm in the waveform height of adjacent corrugated foil layers. That is, the peak height of the upper corrugated foil layer is slightly lower than that of the lower corrugated foil layer. This height difference design makes the corrugated foil assembly exhibit a stepped variable stiffness characteristic when subjected to load: when the working load is small, only the upper corrugated foil layer undergoes major deformation, and the overall stiffness is low; as the load increases, the peak of the upper corrugated foil layer gradually contacts the peak of the lower corrugated foil layer, and the lower corrugated foil layer participates in the load bearing. The overall stiffness increases stepwise with the increase of the number of contact layers; if there are 3 or more corrugated foil layers, this process will trigger more corrugated foil layers to participate in the load bearing as the load further increases. Thus, dynamic adaptation from low stiffness to high stiffness is achieved through a step-by-step contact mechanism, ensuring that stable elastic support can be provided under different working conditions, avoiding excessive deformation or rigid impact.

[0024] In a preferred embodiment, the back plate has several U-shaped grooves on its side, and a pin is provided on the side of the U-shaped groove, the pin being interference-fitted with the ring base.

[0025] In a preferred embodiment, a spacer block is fixedly connected to the side of the ring base near the elastic support.

[0026] In a preferred embodiment, the ring base has a groove on the side near the top plate assembly, and the upper and lower top plates are fitted with the groove with a clearance.

[0027] In this invention, the sealing element can be made of high-temperature resistant alloy materials such as Inconel X-750, Inconel 718, and GH145, which have good corrosion resistance and oxidation resistance at high temperatures, and high strength, relaxation resistance, and good forming and welding performance within a certain temperature range. The bottom is provided with a hollow structure to facilitate air film heat dissipation and alleviate the problem of local temperature rise under high speed and high pressure difference. The sealing foil is spot welded to the upper top plate around the circumference to ensure the integrity and reliability of the seal.

[0028] In this invention, the structural parameters can be selected from the following ranges: the thickness of the flat foil is 0.10~0.20mm; the thickness of the elastic flat strip is 0.05~0.10mm; the thickness of the sealing foil is 0.15~0.30mm, and its thickness is equal to the sum of the thickness of the flat foil and the thickness of the elastic flat strip; both the sealing foil and the top of the flat foil need to be coated with a high-temperature resistant and wear-resistant coating with a coating thickness of 25~75μm; the thickness of the corrugated foil used for the upper and lower corrugated foils and the elastic support is 0.10~0.20mm; the thickness of the upper and lower top plates is 0.15~0.25mm; the groove on the ring base forms a clearance fit with the upper and lower top plates, and the bottom of the groove can leave a 3~8mm margin to accommodate the axial floating of the upper and lower top plates.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses flat foil and sealing foil to form a sealing end face and a multi-layer corrugated foil at the bottom to form a flexible support, so that the seal has gradual flexibility in the axial, radial and circumferential directions. It can automatically adjust the contact pressure distribution when the film thickness is disturbed, effectively solving the problems of end face rubbing, instability or even breakage caused by the inability of the rigid structure to self-compensate in existing dry gas seals and rigid end face seals.

[0030] 2. The foil material used in this invention can be high-temperature resistant alloy materials such as Inconel X-750, Inconel 718, and GH145. Combined with the bottom hollow structure, it improves the strength, corrosion resistance, and heat dissipation capacity of the seal at high temperatures, and overcomes the problems of thermal deformation and reduced air film stiffness caused by insufficient heat exchange under high speed and high pressure differential in the existing technology.

[0031] 3. This invention consists of a multi-layered corrugated foil sheet with a small axial dimension and a flexible support structure. It relies on the gas film dynamic pressure effect to achieve sealing and load-bearing, eliminating the need for a heavy rigid ring and a large loading mechanism. This significantly reduces the axial dimension and makes it more suitable for applications with strict space and weight constraints, such as aero engines and compact gas turbines.

[0032] 4. The present invention effectively blocks leakage gaps by overlapping the sealing foil with the upper and lower top plates, thus solving the problem of media leakage caused by assembly gaps and vibration under high speed and large pressure difference in the prior art, and has better leakage control performance. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0034] Figure 2 This is a schematic diagram of the flat foil installation of the present invention.

[0035] Figure 3 This is a schematic diagram of the installation of the elastic flat strip of the present invention.

[0036] Figure 4 This is a schematic diagram of the installation of the top plate assembly of the present invention.

[0037] Figure 5 This is a schematic diagram of the installation of the corrugated foil assembly of the present invention.

[0038] Figure 6 This is a schematic diagram of the installation of the corrugated foil base plate of the present invention.

[0039] Figure 7 This is a schematic diagram of the backplate installation of the present invention.

[0040] Figure 8 This is a schematic diagram of the installation of the elastic support body of the present invention.

[0041] Figure 9 This is a schematic diagram of the trench of the present invention.

[0042] Figure 10 This is a schematic diagram of the gap region of the present invention.

[0043] Figure 11 This is a schematic diagram of the upper top plate of the present invention.

[0044] Figure 12 This is a schematic diagram of the upper wave foil of the present invention.

[0045] Figure 13 This is a schematic diagram of the U-shaped groove of the present invention.

[0046] Figure 14 This is a schematic diagram of the spacer block of the present invention.

[0047] The attached figures are labeled as follows: 1. Ring base; 2. Elastic support; 3. Back plate; 4. Corrugated foil base plate; 5. Corrugated foil assembly; 6. Top plate assembly; 7. Elastic flat strip; 8. Flat foil; 9. Sealing foil; 801. Gap area; 802. Sloping area; 803. Horizontal area; 601. Upper top plate; 602. Lower top plate; 501. Upper corrugated foil; 502. Lower corrugated foil; 301. U-shaped groove; 302. Pin; 102. Spacer block; 101. Groove. Detailed Implementation

[0048] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0049] like Figure 1-14 As shown, the present invention provides a gas film seal for the end face of a foil in a turbine under extreme operating conditions, comprising a ring base 1, a plurality of elastic supports 2 disposed above the ring base 1, a back plate 3 disposed above the elastic supports 2, a plurality of corrugated foil base plates 4 disposed above the back plate 3, a plurality of corrugated foil assemblies 5 disposed above the corrugated foil assemblies 5, a top plate assembly 6 disposed above the corrugated foil assemblies 5, a plurality of elastic flat strips 7 disposed above the top plate assembly 6, a plurality of flat foils 8 disposed above the elastic flat strips 7, and sealing foils 9 disposed on the inner or outer diameter side of the flat foils 8.

[0050] The flat foil 8 includes a gap area 801, a ramp area 802 and a horizontal area 803. The elastic flat strip 7 is disposed below the horizontal area 803. The gap area 801 is fixedly connected to the top plate assembly 6.

[0051] The top plate assembly 6 includes an upper top plate 601 and a lower top plate 602. The upper top plate 601 is fixedly connected to the elastic flat strip 7, the flat foil 8 and the sealing foil 9. The lower top plate 602 is overlapped with the upper top plate 601.

[0052] The corrugated foil assembly 5 includes at least one layer of corrugated foil sheet. The corrugated foil sheet of the corrugated foil assembly 5 is fixedly connected to the lower top plate 602 and to the corrugated foil sheet bottom plate 4.

[0053] The back plate 3 has several U-shaped grooves 301 on its side, and a pin 302 is provided on the side of the U-shaped groove 301. The pin 302 is interference-fitted with the ring base 1.

[0054] A spacer block 102 is fixedly connected to the side of the ring base 1 near the elastic support 2.

[0055] A groove 101 is provided on the side of the ring base 1 near the top plate assembly 6, and the upper top plate 601 and the lower top plate 602 are fitted with the groove 101 with a clearance.

[0056] Example: In this example, the foil material in the seal can be a high-temperature resistant material such as Inconel X-750, Inconel 718, or GH145 to adapt to the high-temperature and high-speed environment of the aero-engine. An annular groove 101 is provided on the inner side of the bottom ring base 1. A 4mm axial allowance is reserved at the bottom of the groove 101 to allow for axial floating adjustment of the upper top plate 601 and the lower top plate 602 during operation, and both maintain a clearance fit with the groove 101.

[0057] Six elastic support bodies 2 are evenly spot-welded to the top of the ring base 1 along the circumference. The elastic support bodies 2 are made of corrugated foil, each with a thickness of 0.15~0.2mm. Six spacer blocks 102 are fixed to the top of the ring base 1 at positions corresponding to the elastic support bodies 2. The spacer blocks 102 have an axial thickness of 4.5mm, while the elastic support bodies 2 have a height of 6.25mm. They absorb radial and circumferential vibrations through their own elastic deformation and are also limited by the spacer blocks 102 to prevent excessive deformation. Three U-shaped grooves 301 are evenly distributed on the outer edge of the back plate 3. A pin 302 is embedded in each groove. One end of the pin 302 is interference-fitted with the ring base 1, and the other end is engaged in the U-shaped groove 301, forming a circumferential anti-rotation structure.

[0058] Six fan-shaped corrugated foil base plates 4 are spot-welded to the upper surface of the back plate 3, with gaps between adjacent fan-shaped corrugated foil base plates 4 in the circumferential direction; each base plate corresponds to a set of corrugated foil assemblies 5, with gaps between adjacent sets of corrugated foil assemblies 5 in the circumferential direction as well; in addition, gaps are also left between adjacent elastic support bodies 2 in the circumferential direction; the above-mentioned circumferential gaps are used to provide radial deformation space for each component: when the seal undergoes radial displacement or deformation due to temperature changes or load under extreme working conditions, the circumferential gaps can prevent adjacent components from squeezing, colliding or getting stuck, prevent structural damage or deformation failure caused by radial interference, and ensure the stable performance of the multi-directional compensation capability of the flexible support.

[0059] Each corrugated foil assembly 5 consists of an upper corrugated foil 501 and a lower corrugated foil 502, both with a thickness of 0.15~0.2mm. The crests of the upper corrugated foil 501 are spot-welded to the lower surface of the lower top plate 602, while the troughs are spot-welded to the troughs of the lower corrugated foil 502 and the upper surface of the corrugated foil base plate 4. This staggered connection forms a flexible support that can deform in multiple directions.

[0060] An upper top plate 601 is stacked on top of a lower top plate 602. The two are installed by overlapping the upper and lower plates to cover any leakage gaps that may occur at the flange end. The outer edge of the upper top plate 601 is divided into 6 sections. Each section has 8 elastic flat strips 7 circumferentially spot-welded to its upper surface. The elastic flat strips 7 are 0.05~0.07mm thick. They are welded to the lower surface of the horizontal area 803 of the flat foil 8 along the rear edge, raising the horizontal area 803 by 0.05~0.07mm, so that the sloping area 802 of the flat foil 8 and the horizontal area 803 naturally form a wedge-shaped gap. The flat foil 8 is 0.1~0.15mm thick. Its gap area 801 is spot-welded to the upper top plate 601, and the top is coated with a 25~75μm thick wear-resistant coating.

[0061] The sealing foil 9 on the inner diameter side of the flat foil 8 is arranged in a circumferential ring with a thickness of 0.15~0.22mm. The top is also coated with a 25~75μm coating, and the inner edge is spot welded to the upper top plate 601 in the entire circumferential direction.

[0062] This embodiment can adapt to the deformation of the shaft and housing caused by thermal effects and dynamic loads, while maintaining a low leakage level. It also has significant performance advantages in adapting to axial displacement of mating surfaces, assembly errors, non-flat deformation, conical deformation, and circumferential deformation.

[0063] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A film seal on the end face of a foil in a turbine machine operating under extreme conditions, characterized in that: The system includes a ring base (1), above which are a plurality of elastic supports (2), above which is a back plate (3), above which are a plurality of corrugated foil base plates (4), above which are a plurality of corrugated foil assemblies (5), above which is a top plate assembly (6), above which are a plurality of elastic flat strips (7), above which are a plurality of flat foils (8), and on the inner or outer diameter side of the flat foils (8) are sealing foils (9).

2. The extreme-condition turbine machinery foil end-face gas film seal according to claim 1, characterized in that: The flat foil (8) includes a gap area (801), a ramp area (802) and a horizontal area (803). The elastic flat strip (7) is disposed below the horizontal area (803). The gap area (801) is fixedly connected to the top plate assembly (6).

3. The extreme-condition turbine machinery foil end-face gas film seal according to claim 1, characterized in that: The top plate assembly (6) includes an upper top plate (601) and a lower top plate (602). The upper top plate (601) is fixedly connected to an elastic flat strip (7), a flat foil (8) and a sealing foil (9). The lower top plate (602) is overlapped with the upper top plate (601).

4. The extreme-condition turbine machinery foil end-face air film seal according to claim 3, characterized in that: The corrugated foil assembly (5) includes at least one layer of corrugated foil, the corrugated foil of the corrugated foil assembly (5) is fixedly connected to the lower top plate (602) and fixedly connected to the corrugated foil bottom plate (4).

5. The extreme-condition turbine machinery foil end-face gas film seal according to claim 1, characterized in that: The back plate (3) has several U-shaped grooves (301) on its side, and a pin (302) is provided on the side of the U-shaped groove (301). The pin (302) is interference-fitted with the ring base (1).

6. The extreme-condition turbine machinery foil end-face gas film seal according to claim 1, characterized in that: The ring base (1) is fixedly connected to a spacer block (102) on the side near the elastic support (2).

7. The extreme-condition turbine machinery foil end-face air film seal according to claim 3, characterized in that: The ring base (1) has a groove (101) on the side near the top plate assembly (6), and the upper top plate (601) and the lower top plate (602) are fitted with the groove (101) with a clearance.

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