阅读说明：本技术 一种基于间隙逆向补偿的篦齿封严装置 (Labyrinth sealing device based on clearance reverse compensation ) 是由 刘传凯 丁水汀 王家俊 李子俊 邱天 于 2021-08-31 设计创作，主要内容包括：本发明公开一种基于逆向间隙补偿的篦齿封严装置,主要由封严衬套及转轴上轴向布置的多个封严篦齿组成。对于转子件而言,在与正篦齿相反的方向增加倒篦齿；对于静子而言,封严衬套的右端向转轴方向延至略超过倒篦齿齿尖高度后折向篦齿盘方向,与倒篦齿间形成前腔与后腔。当本发明篦齿封严装置中转子件在工作过程中受到载荷影响产生径向位移时,正篦齿、倒篦齿与封严衬套之间的间隙反向变化,形成逆向间隙补偿,减少了径向位移的偏离量造成泄漏量的增大,极大提高了空气系统的鲁棒性。(The invention discloses a labyrinth sealing device based on reverse clearance compensation, which mainly comprises a sealing bush and a plurality of sealing combs axially arranged on a rotating shaft. For the rotor piece, the inverted comb teeth are added in the direction opposite to the positive comb teeth; for the stator, the right end of the sealing bush extends to a position slightly higher than the tooth tip of the inverted labyrinth and then is folded towards the direction of the labyrinth plate towards the direction of the rotating shaft, and a front cavity and a rear cavity are formed between the right end of the sealing bush and the inverted labyrinth. When the rotor member in the labyrinth sealing device is influenced by the load to generate radial displacement in the working process, gaps among the forward labyrinth, the inverted labyrinth and the sealing bush are reversely changed to form reverse gap compensation, so that the increase of leakage caused by the deviation of radial displacement is reduced, and the robustness of an air system is greatly improved.)

1. A labyrinth sealing device based on reverse clearance compensation comprises a labyrinth disc and a sealing bush; more than 2 positive grid teeth are arranged on the grid toothed disc along the axial direction, and the height difference exists among the heights of all the teeth along the axial direction of the rotor and the positive grid teeth are distributed in a step shape; the sealing bush is sleeved outside the rotor, the side wall is axially step-shaped and is matched with the height difference of each tooth in the axial direction of the rotor, the circumferential side wall of each step corresponds to the tooth top of one comb tooth, and a gap is reserved between the tooth top of each tooth and the corresponding step side wall; the method is characterized in that: the grate plate is provided with inverted grates in the direction opposite to the positive grates; meanwhile, the last stage of the sealing bush axially extends to form an axial extension section at the tail end of the bush; further extending along the radial direction of the rotor at the edge of the axial extension section at the tail end of the lining to form a radial section at the tail end of the lining; finally, the edge of the radial section at the tail end of the lining sleeve extends reversely along the axial direction of the rotor to form a reverse extension section at the tail end of the lining sleeve; the axial extension section at the tail end of the lining, the radial section at the tail end of the lining and the reverse extension section at the tail end of the lining are made to wrap the tail end of the grate plate and the grate teeth; a front cavity is formed between the front tooth surface of the inverted comb tooth and the radial section and the reverse extension section of the tail end of the bushing; a rear cavity is formed between the rear tooth surface of the inverted comb and the reverse extension section of the tail end of the bushing;

after sequentially passing through gaps between the tooth tops of the positive labyrinth teeth and the side walls of the sealing bush sleeve, airflow is bent in the rear direction of the rear tooth surface of the final-stage positive labyrinth tooth, flows into the front cavity through the radial sections of the tail end of the labyrinth tooth plate and the tail end of the bush, further flows out after reaching the rear cavity through a gap between the tooth tops of the reverse labyrinth teeth and the reverse extension sections of the tail end of the bush, generates flow resistance through the inter-tooth throttling and the dissipation effect of tooth cavity vortex, and meets the sealing requirement.

2. The labyrinth sealing device based on reverse clearance compensation according to claim 1, characterized in that: the width of the inverted comb tooth top is equal to that of the forward comb tooth top, and the thickness is 0.1-0.3 mm.

3. The labyrinth sealing device based on reverse clearance compensation according to claim 1, characterized in that: the inclination angle of the front tooth surface of the inverted comb tooth is required to be larger than that of the rear tooth surface, the inclination angle of the front tooth surface is designed to be 60-80 degrees, and the inclination angle of the rear tooth surface is designed to be 50-70 degrees.

4. The labyrinth sealing device based on reverse clearance compensation according to claim 1, characterized in that: the section of the inverted comb tooth consists of a large arc, a small arc and two straight lines; the small arc is a transition arc between the root of the front tooth surface of the inverted comb and the grate disc, the radius of the arc is designed to be 1-2 mm, and the corresponding central angle is complementary with the inclination angle of the front tooth surface of the inverted comb; the large circular arc is a circular arc between the root of the back tooth surface of the inverted comb tooth and the comb tooth plate, the radius is designed to be 3-5 mm, and the corresponding central angle is equal to the inclination angle beta of the back tooth surface.

5. The labyrinth sealing device based on reverse clearance compensation according to claim 1, characterized in that: the vertical distance between the top of the inverted comb teeth and the inner side surface of the plate edge of the rear comb tooth plate of the inverted comb teeth is designed to be 5-7 mm, and the vertical distance between the 6 inverted comb teeth and the inner side surface of the plate edge of the front comb tooth plate of the inverted comb teeth is designed to be 4-6 mm.

6. The labyrinth sealing device based on reverse clearance compensation according to claim 1, characterized in that: the thickness of the end plate edge of the grate plate is designed to be 3-4 mm.

Technical Field

The invention relates to the field of aeroengine sealing, in particular to a labyrinth sealing device based on reverse clearance compensation, which can reduce the radial clearance change of a labyrinth.

Background

Along with the development of aviation industry, the performance and the rotating speed of a modern gas turbine engine are continuously improved, the pressure ratio and the turbine inlet temperature are continuously improved, the leakage problem of a sealing system between movable and static parts of the engine is increasingly serious, the quality of a sealing structure directly influences the performance of the engine, the high-quality sealing structure can effectively reduce the leakage of the sealing system, the thrust ratio of the engine is increased, the oil consumption rate is reduced, and the efficiency of the engine is obviously improved. The data show that: the improvement of the performance of the future aeroengine is half of the improvement of the sealing technology and the reduction of the leakage amount; the geometric parameters, the tooth number, the pressure difference before and after the labyrinth and the rotating speed of the labyrinth structure directly influence the flow characteristic and the heat exchange characteristic of the sealed labyrinth in practical application, thereby influencing the efficiency and the fuel consumption rate of an engine device. For commercial aircraft, advanced sealing technology can reduce direct operating costs of aircraft engines by 3% -5% and reduce fuel consumption by 10%. Therefore, advanced sealing technology has become a key factor in terms of fuel consumption, thrust-weight ratio, reliability and durability of the engine.

The traditional stepped labyrinth is a non-contact dynamic sealing structure and is composed of a rotor 1 and a stator 2 as shown in figure 1; the rotor 1 is a grate disc, the inner side surface of the upper disc edge of the rotor is provided with more than 2 grate teeth 3 along the axial direction, and the height difference exists among the height of each grate tooth 3 along the axial direction of the rotor 1 and the grate teeth are distributed in a step shape; a tooth cavity 4 is formed between two adjacent grid teeth 3. The stator 2 is a sealing bush sleeved outside the rotor 1, the side wall of the stator is axially step-shaped and is matched with the height difference of each axial labyrinth of the rotor 1; the circumferential side wall of each stage of step corresponds to the tooth top of one grid tooth 3, and a gap is reserved between the tooth top of each grid tooth 3 and the corresponding step side wall. When the airflow passes through the gap between the tooth top of the grid 3 and the side wall of the step, the airflow is throttled and accelerated to generate a jet flow area, a part of pressure energy is converted into kinetic energy, the airflow collides on the inner wall of the stator to generate a backflow area, and a larger backflow area is generated at the lower part of the tooth cavity 4 due to the structure of the tooth cavity 4. Due to the existence of the backflow areas, the kinetic energy of the airflow is converted into heat energy under the action of turbulent flow and viscous dissipation and is consumed, and finally, the sealing effect is achieved.

In practical application, radial displacement is often generated in the working process of the grate due to load, and the size of the throttling gap is changed, so that the throttling strength is directly influenced, the flow characteristic and the heat exchange characteristic of the grate are directly influenced, the sealing effect of the grate is poor, and harmful accidents such as gas backflow are caused. Theoretically, the smaller the throttling gap, the stronger the sealing effect.

Disclosure of Invention

Aiming at the problems, the invention provides a labyrinth sealing device based on clearance reverse compensation, so that the radial displacement of a labyrinth is reduced, the change of leakage amount is caused, and the device has a remarkable effect on improving the performance and the safety of an engine.

The invention relates to a labyrinth sealing device based on reverse clearance compensation. Wherein, the labyrinth plate is provided with more than 2 positive grates along the axial direction, and the height difference exists between the heights of all the teeth along the axial direction of the rotor, and the positive grates are distributed in a step shape.

The sealing bush is sleeved outside the rotor, the side wall is axially stepped and is matched with the height difference of each tooth in the axial direction of the rotor, the circumferential side wall of each step corresponds to the tooth top of one comb tooth, and a gap is reserved between the tooth top of each tooth and the corresponding step side wall.

The grate plate is also provided with inverted grates in the direction opposite to the positive grates; meanwhile, the last stage of the sealing bush axially extends to form an axial extension section at the tail end of the bush; further extending along the radial direction of the rotor at the edge of the axial extension section at the tail end of the lining to form a radial section at the tail end of the lining; and finally, the edge of the tail end radial section of the lining sleeve extends reversely along the axial direction of the rotor to form a tail end reverse extension section of the lining sleeve. Therefore, the axial extension section at the tail end of the lining, the radial section at the tail end of the lining and the reverse extension section at the tail end of the lining are wrapped on the tail end of the grate plate and the grate teeth; a front cavity is formed between the front tooth surface of the inverted comb tooth and the radial section and the reverse extension section of the tail end of the bushing; the back tooth surface of the inverted comb tooth and the reverse extension section of the tail end of the bushing form a back cavity.

After sequentially passing through gaps between the tooth tops of the positive labyrinth teeth and the side walls of the sealing bush sleeve, airflow is bent in the rear direction of the rear tooth surface of the final-stage positive labyrinth tooth, flows into the front cavity through the radial sections of the tail end of the labyrinth tooth plate and the tail end of the bush, further flows out after reaching the rear cavity through a gap between the tooth tops of the reverse labyrinth teeth and the reverse extension sections of the tail end of the bush, generates flow resistance through the inter-tooth throttling and the dissipation effect of tooth cavity vortex, and meets the sealing requirement.

The invention has the advantages that:

1. compared with the common straight-through shape and the stepped labyrinth, the labyrinth sealing device based on the clearance reverse compensation improves the sealing effect;

2. according to the labyrinth sealing device based on clearance reverse compensation, the reverse clearance compensation structure can reasonably control the leakage flow under the working condition of larger radial clearance, and has an inhibiting effect on the increase of the leakage flow caused by rotor displacement;

3. according to the labyrinth sealing device based on clearance reverse compensation, different tooth top clearances are formed between the upper part and the lower part of the labyrinth, so that the stress of a rotor can be balanced, and the collision and abrasion are reduced;

4. the manufacturing process of the labyrinth sealing device based on clearance reverse compensation is similar to that of a step labyrinth and is simpler.

Drawings

Fig. 1 is a schematic view of a conventional stepped grate structure.

Fig. 2 is a schematic structural view of the labyrinth sealing device of the invention.

FIG. 3 is a schematic view of the flow field of the labyrinth sealing device of the present invention

Fig. 4 is a characteristic diagram of an inverted labyrinth in the labyrinth sealing device of the invention.

Fig. 5 is a comparison graph of the results of the simulated labyrinth sealing device of the invention and the traditional stepped labyrinth under the same conditions.

In the figure:

1-rotor 2-stator 3-comb tooth

4-tooth chamber 5-right comb tooth 6-inverted comb tooth

7-axial extension of the end of the liner 8-radial extension of the end of the liner 9-reverse extension of the end of the liner

10-anterior chamber 11-posterior chamber

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

According to the labyrinth sealing device based on clearance reverse compensation, as shown in fig. 2, compared with the traditional stepped labyrinth, at least one inverted labyrinth 6 opposite to the tooth crest direction of a positive labyrinth 5 is added at the tail end of a rotor 1, the number of the inverted labyrinth 6 is limited by the whole structure, 1-2 inverted labyrinth are preferably designed along the axial direction of the rotor 1, and the inverted labyrinth is designed on the inner side surface of the plate edge of a labyrinth plate. Meanwhile, the tail end of the sealing bush is improved, and the last stage of the sealing bush of the traditional stepped labyrinth is axially extended to form an axial extension section 7 at the tail end of the bush; further extending along the radial direction of the rotor 1 at the edge of the axial extension section 7 at the tail end of the lining to form a radial section 8 at the tail end of the lining; finally, a liner end reverse extension 9 is formed at the edge of the liner end radial section 8 and extends along the axial direction of the rotor 1 in a reverse direction. The tail end of the rotor 1 is wrapped by the designed axial extension section 7 at the tail end of the lining, the radial section 8 at the tail end of the lining and the reverse extension section 9 at the tail end of the lining, so that the inverted comb tooth 6 is positioned in a space surrounded by the three sections. As shown in fig. 3, the front and rear tooth surfaces of each comb tooth on the rotor 1 are distinguished in sequence by airflow, the tooth surface which flows through firstly is a front tooth surface, the tooth surface which flows through secondly is a rear tooth surface, and a front cavity 10 is formed between the front tooth surface of the inverted comb tooth 6 and the radial section 8 and the reverse extension section 9 at the tail end of the bush; a rear cavity 11 is formed between the rear tooth surface of the inverted comb tooth 6 and the reverse extension section 9 at the tail end of the bushing, so that the number of backflow areas is increased, and the flow resistance is increased.

As shown in figure 4, when the labyrinth sealing device is in a reference state (the labyrinth plate is not stressed and does not displace), the size of the gap between the inverted labyrinth 6 and the reverse extension section 9 at the tail end of the lining is equal to the size of the gap between the forward labyrinth 5 and the side wall of the sealing lining sleeve. The tooth top width d of the inverted comb tooth 6 is equal to the tooth top width of the forward comb tooth 5, and the tooth top width d is 0.1-0.3 mm. The inclination angle alpha of the front tooth surface of the inverted comb 6 is designed to be 60-80 degrees, and the inclination angle beta of the rear tooth surface is designed to be 50-70 degrees.

In the labyrinth sealing device, the section of the inverted labyrinth 6 consists of a large arc, a small arc and two straight lines. The small arc is a transition arc between the root of the front tooth surface of the inverted comb tooth 6 and the grate disc, the arc radius Ra is designed to be 1-2 mm, and the corresponding central angle is complementary with the inclination angle alpha of the front tooth surface of the inverted comb tooth 6. The large circular arc is a circular arc between the root of the back tooth surface of the inverted comb 6 and the grate disc, the radius Rb is designed to be 3-5 mm, and the corresponding central angle is equal to the inclination angle beta of the back tooth surface.

The vertical distance a between the top of the inverted comb 6 and the inner side surface of the plate edge of the toothed plate of the rear comb 6 of the inverted comb is designed to be 5-7 mm, and the vertical distance b between the inverted comb 6 and the inner side surface of the plate edge of the toothed plate of the front comb 6 of the inverted comb is designed to be 4-6 mm; the thickness c of the edge of the tail end of the grate disc is designed to be 3-4 mm; the selection mode of the distance e between the bushing tail end radial section 8 and the end face of the grate disc tail end is as follows: the smaller value may be chosen appropriately, taking into account the acceptable axial displacement of the labyrinth plate, i.e. the usual absence of collision with the packing bush.

Under the normal working condition, airflow flows through the front end of the stepped labyrinth and flows into gaps between the tooth tops of all the positive labyrinth 5 and the side wall of the sealing bushing sequentially, the flow direction of the airflow is bent behind the rear tooth surface of the final-stage positive labyrinth 5, the airflow flows into the front cavity 10 through a gap between the tail end of the labyrinth plate and the radial section 8 of the tail end of the bushing and further flows out after reaching the rear cavity 11 through a gap between the tooth top of the inverted labyrinth 6 and the reverse extension section 9 of the tail end of the bushing to generate flow resistance through the inter-tooth throttling and the dissipation effect of tooth cavity vortex, so that the sealing requirement is met. When the labyrinth plate moves radially from a normal working position under the influence of a load, a gap (an upper gap) between the positive labyrinth 5 and the sealing bush is increased, so that the flow capacity of the positive labyrinth 5 is increased, the flow is increased, and the throttling effect is reduced; meanwhile, the clearance (lower clearance) between the inverted labyrinth 6 and the sealing bush is reduced, so that the circulation capacity of the inverted labyrinth 6 is reduced, the throttling effect is increased, a negative feedback mechanism is formed with the positive labyrinth 5, and the increase of the leakage amount caused by the increase of the upper clearance is compensated to a certain extent. Meanwhile, front tooth vortexes and rear tooth vortexes are formed in the front and at the rear of the inverted teeth 6 respectively, the number of vortexes is increased, the flow resistance is further increased, the throttling effect is enhanced, and the condition that the leakage amount is increased due to the fact that the grate disc moves downwards along the radial direction is restrained. In a certain range, the more the grate disc moves downwards, the larger the upper gap is, the more the leakage amount is, but the smaller the lower gap is, the more the reverse gap compensation is, the weaker the flow capacity is, and the larger the flow resistance is. The reverse compensation of the larger gap generated by the inverted comb 6 can still ensure that the leakage amount is in a certain range when the labyrinth plate generates larger radial displacement downwards, and the labyrinth plate can still have good sealing effect when the radial displacement occurs.

Simulation calculation is carried out on the traditional stepped grate and the grate with the clearance reverse compensation designed by the invention within the radial clearance variation range of 0.1-0.7 mm to obtain the comparison result of the leakage coefficients of the two types of grates, as shown in figure 5, the result shows that when the radial displacement of the grate plate is small, the leakage coefficient can be maintained to be basically unchanged; when the radial displacement of the grate plate is larger, the inverted grate 6 is added, so that the effect of gap reverse compensation is generated, the leakage coefficient is reduced along with the increase of the radial gap, the leakage amount is far smaller than that of the traditional stepped grate without the gap reverse compensation, and in a certain range, the larger the radial displacement is, the better the gap reverse compensation effect is, and the lower the leakage amount is. The invention can well meet the sealing requirement even if large radial displacement is generated in the working process.