Novel turbomachinery vector sealing structure

Abstract

The invention discloses a novel turbomachinery vector sealing structure. A vector sealing cavity is formed between a stator shell containing sealing teeth and a rotor. The vector sealing cavity is of a spray pipe type structure in mirror symmetry, and the spray pipe type structure comprises multiple stages of sealing cavities which are sequentially connected end to end and are provided with double throat parts; the sealing cavity is sequentially divided into an expansion section and a contraction section in the airflow flowing direction, and a tooth tip jet flow bypass is arranged between the contraction section and the throat part adjacent to the downstream of the contraction section; the sealing cavity is designed to be of a thrust vectoring nozzle structure with a bypass channel, by means of the tooth cavity pressure difference generated by the throttling effect, bypass jet flow is spontaneously driven to be mixed with main leakage flow, a leakage path is guided to directionally deflect in the circumferential direction and the radial direction, multi-dimensional reconstruction of a sealing flow field is achieved, and the dual purposes of reducing leakage and restraining fluid excitation are achieved. And a new method is provided for reducing sealing leakage and improving the excitation suppression performance of sealing fluid.

Description

Technical Field

[0001] The invention relates to the technical field of sealing structures, in particular to a novel turbine machinery vector sealing structure. Background Art

[0002] Seals are key components for preventing fluid leakage and improving unit operating efficiency in various types of turbine machinery, such as aircraft engines, gas turbines, steam turbines, compressors, and fans. However, as the parameters of turbine machinery media continue to increase, the problem of fluid excitation caused by seals has become increasingly prominent.

[0003] The further development of advanced sealing technology requires comprehensive consideration of both leakage and fluid excitation performance. In the prior art, a variety of configuration improvement schemes are usually proposed based on the traditional labyrinth seal, such as boss seals, staggered tooth seals, and high and low tooth seals. For example, the patent announcement number CN212407573U discloses a "staggered helical tooth labyrinth seal structure", in which the inclination direction of the sealing teeth is opposite to the flow direction, and the adjacent sealing teeth come from the rotating component steam seal body and the stationary component steam seal body, and are staggered.

[0004] Although this type of labyrinth seal effectively improves leakage performance, it has poor stability and is prone to cause fluid excitation problems.

[0005] Or try to process textures (such as honeycomb, hole type, scallop, etc.) on the sealing surface, divide the traditional circumferentially penetrating sealing cavity into independent chambers to enhance the gap damping effect, such as the "bag-type damping sealing structure with circumferentially divergent chambers" disclosed in patent publication number CN110513154A, stator, sealing teeth and circumferential baffles, wherein the stator is divided into a plurality of alternating basic chambers and secondary chambers by the sealing teeth along the axial direction, and there are multiple circumferential baffles, which penetrate the basic chamber and the secondary chamber and are arranged at intervals along the circumference of each chamber to form a plurality of bag-type chambers, and the distance from the upper top surface of each bag-type chamber to the central axis of the stator increases uniformly along the rotation direction of the rotor, forming a circumferentially divergent wedge-shaped gap structure;

[0006] Although the fluid excitation problem is alleviated to a certain extent, the leakage performance of this method is greatly affected by the matching of texture structure and gap size, and it is difficult to achieve an improvement in comprehensive performance.

[0007] Or from the perspective of flow field regulation, exploration has been conducted, and anti-swirl flow technologies represented by anti-swirl grids and jet anti-swirl have been proposed. For example, the patent announcement number CN113606344B discloses a "labyrinth seal based on anti-swirl plates between teeth to optimize rotor dynamic characteristics". Several groups of anti-swirl plate structures are arranged between the sealing teeth on the sealing stator wall. Each group of anti-swirl plate structures is evenly distributed along the circumference and deflected in the reverse rotation direction on the meridian plane so that the airflow flows downstream in the reverse rotation direction through the guide of the anti-swirl plate structure. At the same time, the sealing gap of the upstream sealing teeth and / or downstream sealing teeth adjacent to the anti-swirl plate structure can be changed to expand the radial height of the inter-tooth jet;

[0008] Although significant results have been achieved in suppressing fluid excitation, this type of technology often ignores the performance of leakage performance, and the leakage suppression effect is even worse than that of traditional labyrinth seals.

[0009] The above existing technologies have proposed a variety of improvement schemes from the two aspects of configuration improvement and flow field control, and have made certain progress, but they still cannot achieve the coordinated improvement of "leakage reduction" and "vibration suppression" performance. Summary of the invention

[0010] The object of the present invention is to provide a novel turbine mechanical vector seal structure to solve the problems raised in the above background technology.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A novel turbine mechanical vector seal structure, including a vector seal cavity formed between a stator housing with seal teeth and a rotor;

[0013] The vector sealing cavity is a mirror-symmetrical nozzle-type structure, and the nozzle-type structure includes multiple stages of sealing cavities connected end to end in sequence and having double throats;

[0014] The sealing cavity is divided into an expansion section and a contraction section in sequence along the airflow direction, and a tooth tip jet bypass is arranged between the contraction section and the throat portion adjacent to the contraction section downstream.

[0015] Preferably, the tooth tip jet bypass is arranged on a stator casing containing sealing teeth.

[0016] Preferably, there are multiple groups of outlets of the tooth tip jet bypass evenly arranged along the circumference of the rotor axis.

[0017] Preferably, the outlet extension directions of the plurality of groups of the tooth tip jet bypasses are located in the same plane and are perpendicular to the axial direction of the nozzle type structure.

[0018] Preferably, in a plane, the jet inclination angle formed between the outlet direction of the tooth tip jet bypass and the rotor is 30°-60°.

[0019] Preferably, the inlet of the tooth tip jet bypass extends straight inward from the middle of the contraction section along the axial direction of the sealing cavity.

[0020] Preferably, the inlet of the tooth tip jet bypass is arranged around the rotor axis.

[0021] Preferably, the ratio of the expansion section to the contraction section along the axial direction of the sealing cavity is 2:1-3:1.

[0022] Preferably, the expansion section expands linearly and incrementally, and the contraction section contracts linearly and incrementally.

[0023] Preferably, the expansion angle of the expansion section is 10°-90°; the contraction angle of the contraction section is 90°-170°.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention designs the sealing cavity as a vector nozzle structure with a bypass channel, and uses the tooth cavity pressure difference generated by the throttling effect to spontaneously drive the bypass jet to mix with the main leakage flow, guide the leakage path to deflect in the circumferential and radial directions, and realize the multi-dimensional reconstruction of the sealing flow field, achieving the dual purpose of reducing leakage and suppressing fluid excitation. It provides a new method for reducing sealing leakage and improving the sealing fluid excitation suppression performance.

[0026] The present invention adopts a mirror-symmetrical double-throat vector nozzle type sealing cavity structure to provide a geometric space for radial-circumferential compound deflection of the leakage flow; counter-rotation inducing jet grooves are arranged at the tips of the sealing teeth at each level, and the tooth tip jet is used to induce the leakage flow to undergo radial-circumferential compound deflection in the sealing cavity; the curved and twisted flow pattern in the cavity induced by the tooth tip jet can extend the leakage path, enhance the dissipation of turbulent kinetic energy in the cavity, and increase the flow resistance in the cavity. At the same time, the tooth tip jet forms an "air curtain barrier" at the entrance of each level of sealing cavity, which effectively improves the local flow resistance of the tooth tip and can further enhance the leakage suppression effect. Vector sealing belongs to the tooth cavity collaborative resistance increase scheme, and its leakage suppression performance will be better than the traditional scheme based on resistance increase at the sealing cavity or sealing teeth.

[0027] The tooth tip jet is injected into the sealing cavity in the counter-rotating direction, and the circumferential flow is offset / reversed by momentum collision, suppressing the generation of fluid excitation from the source. Compared with the traditional anti-rotating flow technology, the vector sealing solution has two major advantages: first, the global flow field control is achieved through the series connection of multiple stages of sealing cavities, breaking through the limitations of traditional local jet control; second, the intensity of the anti-rotating jet is automatically adjusted with the sealing pressure difference, forming an adaptive match for high parameter working conditions. The above two points ensure the effectiveness of the vector seal "vibration suppression" and its robustness in a wide range of working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the three-dimensional structure of the vector seal of the present invention;

[0030] Figure 2 This is a cross-sectional view of the seal meridian of the present invention;

[0031] Figure 3 This is a schematic diagram of the tooth tip jet bypass structure on the sealing chamber of the present invention;

[0032] Figure 4 This is a schematic diagram of the sealing chamber structure of the present invention;

[0033] Figure 5 This is a schematic diagram of a traditional labyrinth seal;

[0034] Figure 6 This is a schematic diagram of vector sealing of the present invention;

[0035] Figure 7 The geometric parameters of the traditional labyrinth seal vector seal;

[0036] Figure 8 Key parameter settings and operating conditions for the numerical method of traditional labyrinth seal and vector seal;

[0037] Fig. 9 It is the streamline radial deflection characteristic of the traditional labyrinth seal;

[0038] Fig.10 The streamline radial deflection characteristic of the vector seal of the present invention;

[0039] Fig.11 It is the streamline circumferential deflection characteristic of the traditional labyrinth seal;

[0040] Fig.12 It is the streamline circumferential deflection characteristic of the vector seal of the present invention.

[0041] The reference numerals in the figure are as follows:

[0042] 1. Air flow inlet; 2. Stator housing with sealing teeth; 3. Tooth tip jet bypass; 4. Vector sealing chamber; 5. Rotor; 6. Air flow outlet. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example:

[0045] A novel turbine mechanical vector seal structure includes: a stator housing 2 with seal teeth, a tooth tip jet bypass 3, a rotor 5, and a vector seal chamber 4 formed by the stator housing 2 with seal teeth and the rotor 5. The stator housing 2 with seal teeth and the rotor 5 are coaxially arranged.

[0046] The vector sealing chamber 4 is a mirror-symmetrical vector nozzle structure, which includes multiple stages of sealing chambers connected end to end and having double throats. The vector nozzle structure is parallel to the rotor 5 axis, and two adjacent sealing chambers share a throat. Figure 3-Figure 4 As shown, the sealing chamber is divided into an expansion section and a contraction section in sequence along the airflow direction, and a corresponding tooth tip jet bypass 3 is arranged from the middle of the contraction section to the throat downstream, and a channel is opened in the stator housing 2 containing the sealing teeth to form the tooth tip jet bypass 3. The inlet of the tooth tip jet bypass 3 is relatively around the axis of the rotor 5, and the inlet of the tooth tip jet bypass 3 is relatively extended from the middle position of the contraction section along the axial direction of the rotor 5 to form a ring structure; the outlet of the tooth tip jet bypass 3 is connected from the inlet and extends in a straight line to the middle position of the throat, and there are multiple groups of outlets of the tooth tip jet bypass 3 that are evenly distributed circumferentially with the rotor 5 as the center,

[0047] The outlet extension direction of the tooth tip jet bypass 3 is relatively perpendicular to the axial direction of the rotor 5. In the plane formed by multiple groups of tooth tip jet bypasses 3, the outlets of the tooth tip jet bypass 3 are inclined toward the rotor 5 to form a jet inclination angle.

[0048] With the inlet end of the tooth tip jet bypass 3 as the center, the outlet extension direction of the tooth tip jet bypass 3, the inlet end of the tooth tip jet bypass 3 and the axis of the rotor 5 as two sides to form a jet inclination angle.

[0049] The ratio of the expansion section to the contraction section is controlled at 2:1-3:1, the expansion angle of the expansion section is controlled at 10°-90°; the contraction angle of the contraction section is controlled at 90°-170°.

[0050] like Figure 1 , Figure 2As shown, the working fluid flows from the air flow inlet 1 to the air flow outlet 6. When the working fluid flows through the sealing tooth tip (throat), a throttling effect is generated, and the pressure energy of the working fluid is converted into kinetic energy, causing the pressure at the tooth tip to be lower than the pressure in the upstream sealing cavity. Driven by the pressure difference, a jet with a reverse rotation direction is formed in the tooth tip bypass. Under the action of the jet, the main leakage flow forms a radial-circumferential composite deflection in the vector sealing cavity 4. Among them, the radial deflection component can effectively enhance the dissipation of turbulent kinetic energy in the cavity and increase the leakage flow resistance, while the circumferential deflection component can suppress the circumferential flow in the seal, thereby suppressing the occurrence of airflow excitation from the source.

[0051] In addition, the control effect of the vector seal is adaptively adjusted as the pressure difference between the seal inlet and outlet changes. Specifically, when the pressure difference between the seal inlet and outlet increases, the pressure drop at each level of the seal teeth increases accordingly, and the throttling effect is enhanced. As the throttling effect increases, the bypass jet intensity generated by the tooth tip jet bypass 3 increases synchronously, and the increase in the bypass jet intensity can further enhance the control effect of the radial and circumferential flow in the seal cavity.

[0052] The present invention realizes the reconstruction of the flow field in the sealing cavity by cooperating with the jet induction and the cavity configuration improvement, and achieves the dual purpose of improving the sealing leakage control and the fluid excitation suppression without the need for external energy input.

[0053] like Figure 5-Figure 12 As shown in the figure, the present invention verifies the performance advantage of vector seal by comparing it with the traditional labyrinth seal. Figure 5 , Figure 6 The specific geometric parameters are as shown in Figure 7 The key parameter settings and operating conditions of the numerical method are shown in Figure 8 shown.

[0054] Leakage reduction performance:

[0055] Fig. 9 and Fig.10 The streamline radial deflection characteristics of the labyrinth seal and the vector seal were compared. In the labyrinth seal, the leakage flow passes through the sealing area at a relatively high speed, the leakage path is in a straight line, and the air permeability effect is obvious; while in the vector seal, the leakage flow undergoes obvious radial deflection under the mixing effect of the tooth tip, forming a complex flow pattern with bending and twisting. This flow pattern not only prolongs the leakage path and suppresses the air permeability effect, but also enhances the dissipation of turbulent kinetic energy in the cavity. At the same time, the "air curtain barrier" formed by the tooth tip jet at the entrance of each level of the sealing cavity effectively increases the local flow resistance and further enhances the leakage suppression effect. The study found that the leakage of the vector seal is reduced by about 36% compared with the labyrinth seal, which verifies the starting point of the vector seal to improve the leakage performance by reconstructing the radial flow field.

[0056] Vibration suppression performance:

[0057] Circumferential flow is the root cause of sealing fluid excitation. Whether the circumferential flow can be suppressed or even reversed is the key to achieve vibration suppression. Fig.11 and Fig.12 The streamline deflection characteristics of vector seals and traditional labyrinth seals were compared. The results show that in the labyrinth seal, with the development of leakage flow, the overall flow field morphology shows a significant circumferential deflection phenomenon in the same direction of rotation; while in the vector seal, under the induction of the counter-rotating jet, the sealing domain as a whole presents a circumferential flow morphology in the opposite direction of rotation, and the circumferential flow is completely reversed. The study found that the effective damping of the vector seal is doubled compared with the labyrinth seal, which verifies the purpose of the vector seal to improve the "vibration suppression" performance by regulating the circumferential flow.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0059] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A novel turbomachinery vector seal structure, comprising a vector seal cavity (4) formed between a stator housing (2) and a rotor (5) including seal teeth, characterized in that: The vector sealing chamber (4) is a mirror-symmetrical vector nozzle-type structure, and the vector nozzle-type structure comprises a plurality of sealing chambers connected end to end in sequence and having double throats; The sealed cavity is divided into an expansion section and a contraction section in sequence along the airflow direction, and a tooth tip jet bypass (3) is provided between the contraction section and the throat section adjacent to the contraction section downstream.

2. A novel turbomachinery vector seal structure according to claim 1, characterized in that: The tooth tip jet bypass (3) is arranged on a stator housing (2) containing sealing teeth.

3. A novel turbomachinery vector seal structure according to claim 2, characterized in that: The outlets of the tooth tip jet bypass (3) are arranged in multiple groups evenly along the circumference of the rotor (5) axis.

4. A novel turbomachinery vector seal structure according to claim 3, characterized in that: The outlet extension directions of the plurality of groups of the tooth tip jet bypasses (3) are located in the same plane and are perpendicular to the axial direction of the nozzle type structure.

5. A novel turbomachinery vector seal structure according to claim 4, characterized in that: The jet inclination angle formed by the outlet direction of the tooth tip jet bypass (3) and the rotor (5) in the plane is 30°-60°.

6. A novel turbomachinery vector seal structure according to claim 2, characterized in that: The inlet of the tooth tip jet bypass (3) extends straight inward from the middle of the contraction section along the axial direction of the sealing cavity.

7. A novel turbomachinery vector seal structure according to claim 6, characterized in that: The inlet of the tooth tip jet bypass (3) is arranged around the axis of the rotor (5).

8. The novel turbomachinery vector seal structure according to claim 1 is characterized by: The ratio of the expansion section to the contraction section along the axial direction of the sealing cavity is 2:1-3:

1.

9. A novel turbomachinery vector seal structure according to claim 8, characterized in that: The expansion section expands linearly and incrementally, and the contraction section contracts linearly and incrementally.

10. A novel turbomachinery vector seal structure according to claim 9, characterized in that: The expansion angle of the expansion section is 10°-90°; the contraction angle of the contraction section is 90°-170°.

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