Low-hysteresis low-loss variable-thickness fingertip sealing device

Abstract

The invention relates to a low-hysteresis low-loss variable-thickness fingertip sealing device, and belongs to the technical field of fluid mechanical sealing. The sealing device comprises a rotor, a front baffle, a rear baffle and a sealing piece set clamped between the front baffle and the rear baffle, and is characterized in that a back pressure cavity is formed in the rear baffle, and the sealing piece set is formed by stacking at least three layers of sealing pieces with different thicknesses; the sealing piece I, the sealing piece II and the sealing piece III are sequentially arranged in the direction from the high-pressure side to the low-pressure side of fluid. Reasonable regulation and control of rigidity distribution can be effectively achieved, high fluid loads can be stably borne, through the synergistic effect of the back pressure cavity formed in the rear baffle and the rhombic surface texture of the non-contact area, the working environment of the sealing piece can be optimized, the active utilization capacity of pressure energy of high-pressure fluid can be enhanced, and the sealing piece can be used for sealing the high-pressure fluid. The design contradiction of rigidity-flexibility-energy consumption of a traditional equal-thickness fingertip seal can be relieved fundamentally, and the equal-thickness fingertip seal is suitable for high-parameter, long-service-life and high-reliability rotary mechanical seal scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluid mechanical sealing, in particular to a low-hysteresis and low-loss variable-thickness fingertip sealing device. BACKGROUND

[0002] In the field of high-speed rotating machinery such as aero-engines and gas turbines, the sealing performance between the rotor and the stator is a key factor affecting the operating efficiency, reliability and service life of the equipment. The fingertip seal, with its unique flexible structure, can adapt to the displacement fluctuation of the rotor under working condition changes (such as thermal expansion and contraction during start-up and shutdown, and radial vibration during operation) through the elastic deformation of the thin sheet sealing unit, while blocking the leakage of high-pressure fluid from the high-pressure side to the low-pressure side. It has gradually replaced the traditional labyrinth seal and brush seal, and has become an important development direction of high-end rotating machinery sealing technology. The fingertip seal widely used at present generally adopts a sealing sheet structure with equal thickness. This structure has the following inherent defects: the overall stiffness of the sealing sheet group is difficult to balance the pressure resistance of the high-pressure side and the flexible response of the low-pressure side, and significant elastic hysteresis effect is easily generated when the rotor is subjected to cyclic loading, resulting in increased hysteresis and loss; the tracking ability of the dynamic displacement of the rotor is limited, especially when the rotor experiences rapid radial jumping, the sealing sheet cannot timely adhere to the surface of the rotor due to excessive stiffness or insufficient stiffness, resulting in an increase in the instantaneous sealing gap and an increase in the leakage; the pressure energy of the high-pressure fluid is not effectively utilized, and it is only regarded as a load to be passively resisted, falling into the design contradiction of "thinning the sealing sheet to reduce hysteresis but lacking in pressure resistance, and thickening the sealing sheet to enhance sealing but aggravating hysteresis", which seriously restricts its popularization and application in high-parameter and high-reliability rotating machinery. SUMMARY

[0003] The purpose of the present application is to provide a low-hysteresis and low-loss variable-thickness fingertip sealing device, which has a gradient thickness structure with the sealing sheet group being thick on the high-pressure side and thin on the low-pressure side along the direction of fluid pressure, and combines the advantages of the coordinated layout of the back pressure cavity and the surface texture, etc., to solve the problems of significant hysteresis effect, lagging response to the dynamic displacement of the rotor, insufficient leakage control ability and inability to effectively utilize the pressure energy of the high-pressure fluid caused by the single stiffness of the traditional equal-thickness fingertip seal.

[0004] The present application is implemented according to the following technical solution: a low-hysteresis and low-loss variable-thickness fingertip sealing device, comprising a rotor 4, a front baffle 1, a rear baffle 2 and a sealing sheet group 3 sandwiched between the front baffle 1 and the rear baffle 2, characterized in that: a back pressure cavity 21 is formed on the rear baffle 2, the sealing sheet group 3 is composed of at least three layers of sealing sheets with different thicknesses, and is arranged in order as sealing sheet I 301, sealing sheet II 302 and sealing sheet III 303 along the direction of fluid from the high-pressure side 5 to the low-pressure side 6.

[0005] The thickness of the sealing sheet I 301 is 0.35mm-0.50mm, the thickness of the sealing sheet II 302 is 0.20mm-0.35mm, and the thickness of the sealing sheet III 303 is 0.10mm-0.20mm, so that a variable-thickness gradient structure is formed to reduce hysteresis and loss.

[0006] The front baffle 1 and the rear baffle 2 adopt a ring structure with the same size, so that the clamping force is symmetrically and uniformly applied to both ends of the sealing sheet group 3 in the axial direction.

[0007] On the surface of the rear baffle 2 in contact with the sealing sheet group 3, surface texture 7 is arranged at positions other than the back pressure cavity 21 area, and the texture depth is 10-50μm.

[0008] The surface of the back pressure cavity 21 is directly in contact with the sealing sheet group 3, and a spacer 8 is arranged between the front baffle 1 and the sealing sheet group 3 to compensate for thermal expansion deformation.

[0009] The working principle of the variable-thickness fingertip sealing device with low hysteresis and low loss is that the sealing sheet group 3 adopts a thickness gradient decreasing structure from the high-pressure side 5 to the low-pressure side 6 along the fluid pressure direction, the thicker sealing sheet I 301 on the high-pressure side 5 provides sufficient compression stiffness to stably bear high fluid load and ensure sealing reliability in a high-pressure environment, and the thinner sealing sheet III 302 on the low-pressure side 6 reduces stiffness to achieve rapid response capability, so that the rotor 4 can be sensitively adapted to small radial displacement, the hysteresis effect and energy loss caused by repeated elastic deformation are significantly reduced, and dynamic tracking performance is improved. The device also forms a synergistic system through the surface texture 7 of the back pressure cavity 21 and the contact area of the rear baffle 2, the back pressure cavity 21 introduces part of the leakage fluid to form a supporting pressure, effectively reduces the actual contact area and friction resistance between the sealing sheet and the baffle, reduces the bending moment and contact stress of the sealing sheet root, and the surface texture 7 produces a fretting pressure effect under lubrication or gas medium conditions, improves the interface lubrication state and inhibits wear. The combination of the two not only optimizes the working environment of the sealing sheet, but also enhances the active utilization of high-pressure fluid pressure energy, which fundamentally alleviates the design contradiction between “stiffness-flexibility-energy consumption” of the traditional equal-thickness fingertip sealing. In addition, the front baffle 1 and the rear baffle 2 adopt a ring structure with the same size, so that the clamping force is symmetrically and uniformly applied to both ends of the sealing sheet group in the axial direction, avoiding the distortion, local warping or stress concentration of the sealing sheet caused by misalignment or partial load, and further improving the sealing stability and reliability. The overall design significantly reduces the elastic hysteresis loss through gradient stiffness distribution, improves the self-adaptive tracking capability of the rotor 4 thermal deformation and vibration, and relies on the synergistic effect of the back pressure cavity 21 and the surface texture 7 to actively utilize the leakage fluid energy and optimize the interface lubrication state, effectively realizing the comprehensive advantages of high sealing performance, low energy consumption and long service life, and being particularly suitable for high-end rotating machinery such as aero-engines and gas turbines.

[0010] The present application has the following beneficial effects: 1. The low hysteresis and low loss variable thickness finger seal device, by adopting a gradient thickness seal piece group that thins layer by layer from high pressure side to low pressure side, precisely controls the stiffness distribution, not only guarantees the pressure resistance reliability of the high pressure side, but also improves the dynamic response speed of the low pressure side to the rotor displacement, greatly reduces the hysteresis effect and energy loss, and optimizes the operation efficiency of the sealing system.

[0011] 2. The low hysteresis and low loss variable thickness finger seal device, by the synergistic effect of back pressure cavity and surface texture, actively utilizes the leakage fluid pressure to form supporting force, at the same time improves the interface lubrication and reduces friction and wear, fundamentally relieves the design contradiction of traditional seal, and adapts to the long service life use demand of high parameter and high reliability rotating machinery. BRIEF DESCRIPTION OF DRAWINGS

[0012] Fig. 1 It is a structure perspective view of the low hysteresis and low loss variable thickness finger seal device of the present application. Fig. 2 It is a schematic view of the low hysteresis and low loss variable thickness finger seal device of the present application. Fig. 3 It is a schematic view of the front baffle and rear baffle structure of the present application. Fig. 4 It is a schematic view of the rotor structure of the present application. Fig. 5 It is a schematic view of the seal piece I, seal piece II and seal piece III structure of the present application. Fig. 6 It is a schematic view of the surface texture structure of the present application.

[0013] The numbers in the figure are: 1: front baffle, 2: rear baffle, 21: back pressure cavity, 3: seal piece group, 301: seal piece I, 302: seal piece II, 303: seal piece III, 4: rotor, 5: high pressure side, 6: low pressure side, 7: surface texture, 8: spacer. DETAILED DESCRIPTION

[0014] The present application will be further described below in conjunction with the drawings and examples, but the content of the present application is not limited to the scope described.

[0015] Example 1: as Figs. 1-6As shown in the figure, a low hysteresis and low loss variable thickness finger seal device includes a rotor 4, a front baffle plate 1, a rear baffle plate 2 and a seal sheet group 3 sandwiched between the front baffle plate 1 and the rear baffle plate 2, characterized in that: the rear baffle plate 2 is provided with a back pressure cavity 21, the seal sheet group 3 is composed of at least three layers of seal sheets with different thicknesses, and is sequentially provided with seal sheet I 301, seal sheet II 302 and seal sheet III 303 along the direction of fluid from high pressure side 5 to low pressure side 6. The thickness of seal sheet I 301 is 0.35mm, the thickness of seal sheet II 302 is 0.20mm, and the thickness of seal sheet III 303 is 0.10mm, forming a variable thickness gradient structure to reduce hysteresis and loss. The front baffle plate 1 and the rear baffle plate 2 adopt the same annular structure to ensure that the clamping force acts symmetrically and uniformly on both ends of the seal sheet group 3 along the axial direction. Among the surfaces of the rear baffle plate 2 and the seal sheet group 3 in contact, except for the area of the back pressure cavity 21, the rest of the positions are provided with surface texture 7, which is a diamond surface texture, which improves lubrication and reduces friction and wear through the effect of micro motion pressure, and the texture depth is 10μm. The surface of the back pressure cavity 21 directly contacts the seal sheet group 3, and a spacer 8 is provided between the front baffle plate 1 and the seal sheet group 3 to compensate for thermal expansion deformation.

[0016] Example 2: as Figs. 1-6 As shown in the figure, a low hysteresis and low loss variable thickness finger seal device includes a rotor 4, a front baffle plate 1, a rear baffle plate 2 and a seal sheet group 3 sandwiched between the front baffle plate 1 and the rear baffle plate 2, characterized in that: the rear baffle plate 2 is provided with a back pressure cavity 21, the seal sheet group 3 is composed of at least three layers of seal sheets with different thicknesses, and is sequentially provided with seal sheet I 301, seal sheet II 302 and seal sheet III 303 along the direction of fluid from high pressure side 5 to low pressure side 6. The thickness of seal sheet I 301 is 0.45mm, the thickness of seal sheet II 302 is 0.30mm, and the thickness of seal sheet III 303 is 0.15mm, forming a variable thickness gradient structure to reduce hysteresis and loss. The front baffle plate 1 and the rear baffle plate 2 adopt the same annular structure to ensure that the clamping force acts symmetrically and uniformly on both ends of the seal sheet group 3 along the axial direction. Among the surfaces of the rear baffle plate 2 and the seal sheet group 3 in contact, except for the area of the back pressure cavity 21, the rest of the positions are provided with surface texture 7, which is a diamond surface texture, which improves lubrication and reduces friction and wear through the effect of micro motion pressure, and the texture depth is 10-50μm. The surface of the back pressure cavity 21 directly contacts the seal sheet group 3, and a spacer 8 is provided between the front baffle plate 1 and the seal sheet group 3 to compensate for thermal expansion deformation.

[0017] Example 3: as Figs. 1-6As shown, a low hysteresis and low loss variable thickness finger seal device, comprising a rotor 4, a front baffle plate 1, a rear baffle plate 2 and a seal piece group 3 sandwiched between the front baffle plate 1 and the rear baffle plate 2, characterized in that: the rear baffle plate 2 is provided with a back pressure cavity 21, the seal piece group 3 is composed of at least three layers of seal pieces with different thicknesses, and is sequentially provided with a seal piece I 301, a seal piece II 302 and a seal piece III 303 along the direction of fluid from the high pressure side 5 to the low pressure side 6. The thickness of the seal piece I 301 is 0.50 mm, the thickness of the seal piece II 302 is 0.35 mm, and the thickness of the seal piece III 303 is 0.20 mm, forming a variable thickness gradient structure to reduce hysteresis and loss. The front baffle plate 1 and the rear baffle plate 2 adopt an annular structure with the same size, ensuring that the clamping force acts on both ends of the seal piece group 3 symmetrically and uniformly along the axial direction. Among the surfaces of the rear baffle plate 2 in contact with the seal piece group 3, surface texture 7 is provided at positions other than the back pressure cavity 21 area, and the texture depth is 10-50 μm. The surface of the back pressure cavity 21 is in direct contact with the seal piece group 3, and a spacer 8 is provided between the front baffle plate 1 and the seal piece group 3 to compensate for thermal expansion deformation.

[0018] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A low-hysteresis, low-loss variable-thickness fingertip sealing device, comprising a rotor (4), a front baffle (1), a rear baffle (2), and a sealing sheet assembly (3) sandwiched between the front baffle (1) and the rear baffle (2), characterized in that: The back pressure chamber (21) is provided on the rear baffle (2). The sealing sheet group (3) is composed of at least three layers of sealing sheets with different thicknesses, which are arranged in sequence as sealing sheet I (301), sealing sheet II (302) and sealing sheet III (303) along the direction of fluid from high pressure side (5) to low pressure side (6).

2. The low-hysteresis, low-loss variable-thickness fingertip sealing device according to claim 1, characterized in that: The thickness of sealing sheet I (301) is 0.35mm to 0.50mm, the thickness of sealing sheet II (302) is 0.20mm to 0.35mm, and the thickness of sealing sheet III (303) is 0.10mm to 0.20mm, forming a variable thickness gradient structure to reduce hysteresis and loss.

3. The low-hysteresis, low-loss variable-thickness fingertip sealing device according to claim 1, characterized in that: The front baffle (1) and the rear baffle (2) adopt an annular structure with the same external dimensions to ensure that the clamping force is applied symmetrically and evenly along the axial direction to both ends of the sealing plate group (3).

4. The low-hysteresis, low-loss variable-thickness fingertip sealing device according to claim 1, characterized in that: In the surface of the rear baffle (2) that contacts the sealing sheet group (3), except for the back pressure cavity (21) area, the other positions are provided with surface texture (7), and the texture depth is 10-50μm.

5. The low-hysteresis, low-loss variable-thickness fingertip sealing device according to claim 1, characterized in that: The surface of the back pressure chamber (21) is in direct contact with the sealing sheet group (3), and a partition (8) is provided between the front baffle (1) and the sealing sheet group (3) to compensate for thermal expansion deformation.

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