A flexible non-contact sealing device for a gas turbine

Abstract

The present invention provides a flexible non-contact sealing device for a gas turbine. The flexible non-contact sealing device forms a fluid film containing water vapor with the surface of the rotating shaft of the gas turbine. It includes a front baffle (1), a high-pressure fingertip ring (2), a low-pressure fingertip ring (3) and a rear baffle (4). A plurality of axial boots (5) are arranged on the low-pressure fingertip ring (3). The axial boots (5) are arranged along the inner ring circumference of the low-pressure fingertip ring (3) and extend along the axial direction. The axial boot (5) includes a first surface facing the inner ring surface of the rear baffle (4) and a second surface in contact with the flow boundary layer. The second surface is provided with a plurality of microstructures for increasing the bearing capacity of the fluid film and / or collecting water vapor, which can greatly reduce the friction and wear of the contact surface between the seal and the rotor and reduce leakage.

Description

Technical Field

[0001] The present invention relates to a new type of hydrogen-oxygen gas turbine, and more particularly to a flexible non-contact sealing device for a hydrogen-oxygen gas turbine. Background Art

[0002] In aero-engines and gas turbines, it is necessary to seal the internal fluid to reduce leakage and ensure the normal and efficient operation of the gas turbine. The hydrogen-oxygen gas turbine is a new generation of gas turbine with the characteristics of high efficiency and near-zero emissions in the future. Developing a new generation of non-contact sealing technology is regarded as an effective way to improve the efficiency of future gas turbines. However, during the operation of the hydrogen-oxygen gas turbine, due to the participation of high-density and low-viscosity water vapor in the cycle, special problems such as multiphase condensation flow, high-temperature corrosion, and end face friction exist in the sealing gap.

[0003] Researchers at the National Aeronautics and Space Administration of the United States designed a non-contact fingertip seal in order to overcome the inherent defects of contact flexible seals, such as wear and easy heating. An axial boot (5)-like structure is added to the bottom end of the fingertip beam of this seal, and a gas film is formed between the bottom of the sealing boot and the surface of the rotating shaft during operation to achieve non-contact operation. The main difficulty lies in maintaining a stable gas film and effectively suppressing leakage. Among them, Patent CN204921054U discloses a flexible fingertip seal, which includes a front baffle (1). A gasket, a high-pressure fingertip seal piece, a low-pressure fingertip seal piece, and a rear baffle (4) are sequentially connected to the front baffle (1). An arc-shaped fingertip beam b is provided on the high-pressure fingertip seal piece, and an arc-shaped fingertip beam a is provided on the low-pressure fingertip seal piece. A fingertip boot is connected to the low-pressure fingertip seal piece; the notches of the fingertip beam b and the fingertip beam a face the edges of the high-pressure fingertip seal piece and the low-pressure fingertip seal piece respectively. The cross-sections of the fingertip beam b and the fingertip beam a are variable cross-sections, and the cross-section of the fingertip beam b is the largest near the edge of the high-pressure fingertip seal piece, and the cross-section of the fingertip beam a is the largest near the edge of the low-pressure fingertip seal piece. Although the above design improves the bearing capacity of the gas film to a certain extent, due to the limitation of the non-contact seal shape, the improvement degree of the gas film bearing capacity is limited.

[0004] In view of the above problems, the present invention is specifically proposed. Summary of the Invention

[0005] The main object of the present invention is to provide a flexible non-contact sealing device for a gas turbine to solve the problem that the bearing capacity of the gas film in the prior art cannot meet the requirements.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a flexible non-contact sealing device for a gas turbine. The flexible non-contact sealing device forms a fluid film containing water vapor with the surface of the rotating shaft of the gas turbine, and includes a front baffle, a high-pressure fingertip ring, a low-pressure fingertip ring and a rear baffle. A plurality of axial boots are provided on the low-pressure fingertip ring. The axial boots are arranged along the inner circumferential of the low-pressure fingertip ring and extend along the axial direction. The axial boot includes a first surface facing the inner ring surface of the rear baffle and a second surface in contact with the fluid film. The second surface is provided with a plurality of microstructures for increasing the bearing capacity of the fluid film and / or collecting water vapor. That is, the microstructures can be used to increase the bearing capacity of the fluid film, the microstructures for water vapor, or the microstructures that can increase the bearing capacity of the fluid film and water vapor.

[0007] Further, the microstructure includes a first microstructure for increasing the bearing capacity of the fluid film.

[0008] Further, the first microstructure is a converging structure, and the converging structure is a structure with gradually decreasing geometric dimensions. The converging structure is used to improve the bearing capacity of the fluid film and greatly reduce the friction and wear of the contact surface between the seal and the rotor.

[0009] Further, a plurality of converging structures are arranged at the end of the axial boot adjacent to the low-pressure fingertip ring, and the converging direction of the converging structure is the same as the flow direction of the gas in the fluid film.

[0010] Further, the converging structure is in the shape of a water droplet.

[0011] Further, the microstructure further includes a plurality of second microstructures, and the second microstructures can collect water vapor and can realize the collection of water vapor in the gas turbine.

[0012] Further, a plurality of second microstructures are arranged along the flow direction of the gas in the fluid film.

[0013] Further, in the flow direction of the gas in the fluid film, the plurality of second microstructures are arranged in decreasing order of geometric size for reducing the direct-through effect. Moreover, the gas flow generates vortices when entering the hemispherical geometric structure, which is beneficial to dissipating the kinetic energy of the leakage gas and reducing leakage. The arrangement from large to small can gradually change the large-size vortices in the geometric structure into small-size vortices, induce the separation of the flow boundary layer of the gas in the gap, reduce the direct-through effect, and further reduce leakage.

[0014] Further, the center line direction of the second microstructure is the same as that of the first microstructure.

[0015] Further, the second microstructure is a hemispherical structure.

[0016] Further, the axial boot and the low-pressure fingertip ring are integrally formed.

[0017] Further, the high-pressure fingertip ring and the low-pressure fingertip ring are located between the front baffle and the rear baffle.

[0018] Further, the front baffle, the high-pressure fingertip ring, the low-pressure fingertip ring and the rear baffle are riveted by axially uniformly distributed rivets to form a combined structure.

[0019] Applying the technical solution of the present invention, a flexible non-contact sealing device suitable for a new working medium of a hydrogen-oxygen combustor, which is efficient and stable, is designed; the three-dimensional water-drop-shaped convergent structure can generate a significant hydrodynamic pressure effect, increase the air film bearing capacity, and can greatly reduce the friction and wear of the contact surface between the seal and the rotor; the hemispherical geometric structure has the function of collecting water vapor in the hydrogen-oxygen combustor, and the arrangement from large to small can gradually change the large-scale vortices in the geometric structure into small-scale vortices, inducing the separation of the flow boundary layer of the gas in the gap, reducing the direct-through effect, and further reducing leakage. At the same time, the hemispherical geometric structure can generate vortices, which is beneficial to dissipating the kinetic energy of the leaked gas and reducing leakage. Description of the Drawings

[0020] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 Shows a schematic diagram of a flexible non-contact sealing device according to Embodiment 1 of the present invention; and

[0022] Figure 2 Shows according to Figure 1 A partial enlarged schematic diagram;

[0023] Figure 3 Shows according to Figure 2 A B-B cross-sectional view;

[0024] Figure 4 Shows a schematic diagram of an axial boot micro-structure according to Embodiment 2;

[0025] Figure 5 Shows according to Figure 4 A C-C cross-sectional view;

[0026] Figure 6 Shows a schematic diagram of an axial boot micro-structure according to Embodiment 3;

[0027] Figure 7 Shows according to Figure 6 A D-D cross-sectional view.

[0028] Among them, the above-mentioned drawings include the following reference numerals:

[0029] 1. Front baffle; 2. High-voltage fingertip ring; 3. Low-voltage fingertip ring; 4. Rear baffle; 5. Axial boot; Z. Rotor rotation direction; X. Axial direction. Detailed implementation manners

[0030] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0031] The present invention will be further described in detail below in combination with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present invention. The term "comprising" indicates the presence of features when used, but does not exclude the presence or addition of one or more other features; the orientation or positional relationships indicated by the terms "transverse", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for convenience of 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 thus cannot be construed as a limitation on the present invention; in addition, the terms "first", "second", etc. are used to distinguish different objects, rather than to describe a specific order.

[0032] In the description, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In addition, in the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0033] Hydrogen-oxygen gas turbines are the next generation of gas turbines with the characteristics of high efficiency and near-zero emissions. Developing a new generation of non-contact sealing technology is regarded as an effective way to improve the efficiency of future gas turbines. The non-contact sealing structure forms a gap of dozens of microns to hundreds of microns with the rotating shaft, and a fluid film, that is, an air film, is formed under the movement of the rotating shaft. Under the bearing capacity of the air film, the friction and wear between the non-contact sealing structure and the contact surface of the rotating shaft can be reduced. In the existing technical solutions, although non-contact sealing can improve and stabilize the bearing capacity of the air film in the sealing gap and reduce the friction and wear between the seal and the contact surface of the rotor, due to the limitations of the current non-contact sealing shape, the improvement degree of the air film bearing capacity is limited.

[0034] The present invention provides a novel flexible non - contact sealing device. The flexible non - contact sealing device forms a fluid film containing water vapor on the surface of the rotating shaft of a gas turbine, and includes a front baffle 1, a high - pressure fingertip ring 2, a low - pressure fingertip ring 3 and a rear baffle 4. A plurality of axial boots 5 are arranged on the low - pressure fingertip ring 3. The axial boots 5 are sheet - like structures, which are arranged along the inner - ring circumference of the low - pressure fingertip ring 3 and extend along the axial direction X of the flexible non - contact sealing device. In order to improve the air - film bearing capacity of the sealing gap, the axial boots 5 are specially designed, including a first surface facing the inner - ring surface of the rear baffle 4 and a second surface in contact with the fluid film. The second surface is provided with a plurality of micro - structures for increasing the fluid - film bearing capacity and / or collecting water vapor, that is, the micro - structures can be used to increase the fluid - film bearing capacity, the micro - structures for water vapor, or the micro - structures that can increase both the fluid - film bearing capacity and water vapor.

[0035] As Figure 1 shown, the front baffle 1 and the rear baffle 4 are located at both ends of the flexible non - contact sealing device, and the high - pressure fingertip ring 2 and the low - pressure fingertip ring 3 are arranged in the middle. The front baffle 1, the high - pressure fingertip ring 2, the low - pressure fingertip ring 3 and the rear baffle 4 are riveted by axially - evenly - distributed rivets to form a combined structure, where the thickness of the high - pressure fingertip ring 2 is 1 mm; the thickness of the low - pressure fingertip ring 3 is 1 mm; the thickness of the axial boot 5 is 7.5 mm; the thickness of the whole sealing device is about 15 mm. The material is a nickel - based or cobalt - based superalloy with heat resistance, wear resistance, good toughness, elasticity and high mechanical properties.

[0036] Among them, spiral slits are provided on both the high - pressure fingertip ring 2 and the low - pressure fingertip ring 3, and the spiral slits are processed by means such as electric - discharge machining and laser cutting. A flexible fingertip is formed between every two helical lines, thus forming a flexible non - contact sealing device. Figure 1 In the flexible non - contact sealing device shown, the axial boot 5 is integrally formed with the low - pressure fingertip ring 3 and is cut along the helical line by means such as electric - discharge machining and laser cutting to form a series of slits, where the helical - line cutting slits of the low - pressure fingertip ring 3 and the cutting slits of the axial boot 5 have common endpoints. And the number of the axial boots 5 affects the stiffness of the flexible non - contact sealing device. The number range of the axial boots 5 is 20 - 80. When the number of the axial boots 5 is large, the flexibility is good; when the number of the axial boots 5 is small, the stiffness is good.

[0037] The micro - structures in the first embodiment include a first micro - structure and a second micro - structure, as Figure 2As shown. The first microstructure is used to increase the bearing capacity of the fluid film. The first microstructure is a converging structure with gradually decreasing geometric dimensions. A plurality of converging structures are arranged at the end of the axial shoe 5 adjacent to the low-pressure fingertip ring 3, and the converging direction of the converging structure is the same as the flow direction of the gas in the fluid film. The converging structure can improve the hydrodynamic effect and increase the bearing capacity of the fluid film. Among them, the converging structure is a wedge structure, which is arranged at the end of the axial shoe 5 adjacent to the low-pressure fingertip ring 3, that is, at the air inlet on the bottom surface of the axial shoe 5. The converging structure can be designed into a three-dimensional water-drop-shaped converging wedge structure, or can be designed into a triangular structure, a triangular pyramid structure, a trapezoidal structure, etc. This design is conducive to generating a significant hydrodynamic effect, significantly improving the bearing capacity of the gas film, and greatly reducing the friction and wear of the contact surface between the seal and the rotor.

[0038] The second microstructure can collect water vapor. A plurality of second microstructures are arranged along the flow direction of the gas in the fluid film. In the flow direction of the gas in the fluid film, the plurality of second microstructures are arranged in decreasing order of geometric size for reducing the direct-through effect. The center line direction of the second microstructure is the same as that of the first microstructure. Among them, the second microstructure can be designed as a hemispherical structure, an elliptical structure, etc. As Figures 2 - 3 shown, a series of geometric structures arranged from large to small are designed in the air flow direction of the axial shoe 5, which can realize the collection of water vapor in the gas turbine. Moreover, the air flow generates vortices when entering the geometric structure of the hemispherical shape, which is beneficial to dissipating the kinetic energy of the leakage gas and reducing leakage. The arrangement from large to small can gradually change the large-size vortices in the geometric structure into small-size vortices, induce the separation of the flow boundary layer of the gas in the gap, reduce the direct-through effect, and further reduce leakage.

[0039] When the gas turbine rotor rotates, in the case of the non-contact seal structure and the shaft gap, it drives the air flow in the axial direction to form a gas film, and the flow direction of the gas film is the same as the direction of the gas turbine rotor. As Figures 1 - 3 shown, when the rotor turns to Z, when the axial air flow in the seal gap enters the microstructures on the axial shoe 5 of the low-pressure fingertip ring 3, the air flow first enters the three-dimensional water-drop-shaped converging structure, generating a significant hydrodynamic effect, increasing the bearing capacity of the gas film, and greatly reducing the friction and wear of the contact surface between the seal and the rotor. Then, it sequentially enters the geometric structures of the hemispherical shape arranged from large to small, which can collect the water vapor in the gas turbine, and at the same time generate vortices that are beneficial to dissipating the kinetic energy of the leakage gas and reducing leakage. Furthermore, the arrangement from large to small can gradually change the large-size vortices in the geometric structure into small-size vortices, induce the separation of the flow boundary layer of the gas in the gap, reduce the direct-through effect, and further reduce leakage.

[0040] The microstructures in the second embodiment are set to only include the first microstructure, as Figures 4 - 5 shown. This structural design can be selected and used according to specific needs.

[0041] The micro-structure of the third embodiment is set to include only the second micro-structure, such as Figures 6 - 7 shown. This structural design can be selected for use according to specific needs.

[0042] This new type of flexible non-contact sealing device focuses on improving the microporous structure size, significantly reducing the sealing leakage and friction wear, and also enhancing the water vapor collection effect. Moreover, the convergent structure and the hemispherical design structure are relatively conventional, and the processing cost is low.

[0043] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: The present invention designs a flexible non-contact sealing device that is applicable to the new working medium of a hydrogen-oxygen combustion engine, efficient, and stable; the three-dimensional water droplet-shaped convergent structure can generate a significant dynamic pressure effect, increase the air film bearing capacity, and can greatly reduce the friction and wear of the contact surface between the seal and the rotor; the hemispherical geometric structure has the function of collecting water vapor in the hydrogen-oxygen combustion engine. The arrangement from large to small can gradually change the large-scale vortices in the geometric structure into small-scale vortices, induce the separation of the flow boundary layer of the gas in the gap, reduce the direct-through effect, and further reduce leakage. At the same time, the hemispherical geometric structure can generate vortices, which is beneficial to dissipating the kinetic energy of the leaked gas and reducing leakage.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flexible non-contact sealing device for a gas turbine, wherein the flexible non-contact sealing device forms a fluid film mixed with water vapor with the surface of the rotating shaft of the gas turbine, characterized in that: It includes a front baffle (1), a high-voltage fingertip ring (2), a low-voltage fingertip ring (3) and a rear baffle (4). A plurality of axial boots (5) are provided on the low-voltage fingertip ring (3). The axial boots (5) are arranged along the inner circumference of the low-voltage fingertip ring (3) and extend along the axial direction. The axial boot (5) includes a first surface facing the inner surface of the rear baffle (4) and a second surface in contact with the fluid film. The second surface is provided with a plurality of microstructures for increasing the bearing capacity of the fluid film and collecting the water vapor. A spiral slit is provided on the low-voltage fingertip ring (3), and the spiral slit and the cutting slit of the axial boot (5) have a common end point; The microstructure includes a first microstructure for increasing the bearing capacity of the fluid film. The first microstructure is a converging structure, and the converging structure is a structure with gradually decreasing geometric dimensions, which is used to improve the bearing capacity of the fluid film. The microstructure also includes a plurality of second microstructures that can collect the water vapor. The plurality of second microstructures are arranged along the flow direction of the gas in the fluid film. In the flow direction of the gas in the fluid film, the plurality of second microstructures are arranged in descending order of geometric dimensions, inducing the separation of the flow boundary layer of the gas in the fluid film to reduce the direct-through effect.

2. The non-contact sealing device according to claim 1, wherein A plurality of the converging structures are arranged at the end of the axial boot (5) adjacent to the low-voltage fingertip ring (3), and the converging direction of the converging structure is the same as the flow direction of the gas in the fluid film.

3. The non-contact sealing device according to claim 1, characterized in that, The converging structure is in the shape of a water droplet.

4. The non-contact sealing device according to claim 3, wherein The center line direction of the second microstructure is the same as that of the first microstructure.

5. The non-contact sealing device according to claim 3, characterized in that, The second microstructure is a hemispherical structure.

6. The non-contact sealing device according to any one of claims 1-5, characterized in that, The axial boot (5) and the low-voltage fingertip ring (3) are integrally formed.

7. The non-contact sealing device according to claim 1, wherein, The high-voltage fingertip ring (2) and the low-voltage fingertip ring (3) are located between the front baffle (1) and the rear baffle (4).

8. The non-contact sealing device according to claim 7, characterized in that The front baffle (1), the high-voltage fingertip ring (2), the low-voltage fingertip ring (3) and the rear baffle (4) are riveted by axially evenly distributed rivets to form a combined structure.

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