CN115898559B - A high-efficiency turbine disc cavity air supply structure with pre-swirl nozzle - Google Patents

Abstract

The invention discloses a high-efficiency turbine disc cavity air supply structure with a pre-rotation nozzle, which comprises a rotatable intermediate shaft and an air inlet cylinder, wherein the air inlet cylinder is sleeved outside the intermediate shaft and a gap is reserved between the air inlet cylinder and the intermediate shaft, one side, close to the intermediate shaft, of the air inlet cylinder is provided with an air outlet groove, and the air outlet groove is internally connected with the pre-rotation nozzle in a clamping way. The flow direction of cooling air is controlled by arranging the pre-rotation nozzle, so that the device has a good guiding effect, excessive air turbulence is avoided in the cold air transmission process, the energy loss is reduced, the cooling air flow speed can be accelerated by the pre-rotation nozzle, the cold air can also obtain the rotation direction in the same direction as the middle shaft in the pre-rotation nozzle, the cooling effect can be improved, the service life of the device is greatly prolonged, meanwhile, the device is clamped and connected for convenient disassembly and replacement, cleaning and maintenance, the system operation stability is improved, the functional integrity of the pre-rotation nozzle is ensured, and the smooth circulation of the cold air is benefited.

Description

A high-efficiency turbine disc cavity air supply structure with pre-swirl nozzle

Technical Field

The invention relates to the field of gas turbine discs, and in particular to a high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle.

Background Art

With the development of turbine disk technology, the high speed increase of turbine disk speed has brought about efficient technological improvement, but it has also led to the problems of effective energy utilization and sustainable utilization of equipment. The turbine disk will be subjected to a large amount of heat transfer during operation. Under high temperature, high pressure and high speed working conditions, the mechanical life of various parts of the turbine disk is seriously affected. Therefore, various cooling measures for the working process of the turbine disk have been paid attention to and developed.

For example, the publication number "CN113638777A" discloses "a turbine outer ring clamp, a cooling structure of a turbine outer ring, a turbine and an engine", including a top circle and a fulcrum; the fulcrum is arranged below the top circle; the turbine outer ring clamp is an annular structure with a notch; the top circle is used to withstand the impact cooling of the cooling gas and to divert the cooling gas; the fulcrum is a positioning point, which is used to support the turbine outer ring clamp. The cooling structure of the turbine outer ring includes a casing, a turbine outer ring, a turbine outer ring clamp and a sealing sheet. The turbine includes a cooling structure of the turbine outer ring. The engine includes a turbine. However, in actual applications, the cooling air will generate turbulence and convection due to the lack of a good guiding device, consuming part of the energy, and the utilization efficiency of the cooling air is low. In addition, the inconsistent positions of the components in the turbine device from the fuel gas will result in different heating conditions of the components. The lack of a guiding device will reduce the utilization efficiency of the cooling air and the cooling effect.

Summary of the invention

In view of the problems in the prior art mentioned in the background technology that the cooling air has no guide device to guide the cooling air, there is convection turbulence, and the cooling efficiency and cooling quality are affected, the present invention provides a high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle, and the pre-swirl nozzle is arranged to control the flow direction of the cooling air so that the cooling air is transferred to the heat higher parts to avoid excessive air turbulence and reduce energy loss. The pre-swirl nozzle can accelerate the cooling air flow rate and improve the cooling effect. At the same time, the snap-fit connection facilitates disassembly, replacement, cleaning and maintenance, thereby improving the system operation stability, ensuring the functional integrity of the pre-swirl nozzle, and facilitating the smooth circulation of cold air.

The second invention objective of the present invention is to make the air intake and outlet of the pre-swirl nozzle smoother, more in line with the flow characteristics of cold air, and reduce the mutual interference between cold air in different air paths.

To achieve the above objectives, the present invention adopts the following technical solutions.

A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle includes a rotatable intermediate shaft and an air intake cylinder. The air intake cylinder is sleeved outside the intermediate shaft with a gap between the air intake cylinder and the intermediate shaft. An air outlet groove is provided on one side of the air intake cylinder close to the intermediate shaft, and a pre-swirl nozzle is snap-connected in the air outlet groove. The pre-swirl nozzle arranged in the air supply system is located between the intake cylinder and the intermediate shaft. After the cold air enters the intake cylinder, the cold air is transmitted to the gap between the intermediate shaft and the intake cylinder through the pre-swirl nozzle arranged in the air outlet groove. The gap extends all the way through the entire turbine disk device, so the cold air can be transmitted along the gap to the inside of each turbine disk. Therefore, the gap is also the cooling passage of the entire device, especially for the parts such as the moving blades that directly contact the combustion gas, to effectively cool down the parts to avoid excessive temperature and reduce the service life of the internal device. At the same time, a plurality of nozzle channels are arranged in the pre-swirl nozzle for transmitting cold air. Since the intake cylinder is fixed and the intermediate shaft rotates around the axis of rotation, the nozzle channel inside the pre-swirl nozzle is oriented in the direction of rotation, so that the cold air can be transmitted more closely to the surface of the center axis. The nozzle channel has a good guiding effect during operation. At the same time, the diameter of the air inlet of the pre-swirl nozzle is generally larger than the diameter of the air outlet, which has an accelerating effect on the cold air.

Preferably, the air inlet cylinder is connected to a sealing cylinder at one end close to the turbine disk, and the pre-swirl nozzle is arranged between the air inlet cylinder and the sealing cylinder. The sealing cylinder is closer to the turbine disk than the air inlet cylinder, and the pre-swirl nozzle is arranged between the air inlet cylinder and the sealing cylinder, which can effectively reduce the loss stroke of the accelerated cold air during the transmission process. The pre-swirl nozzle is arranged between the air inlet cylinder and the sealing cylinder to facilitate the subsequent replacement of the pre-swirl nozzle.

Preferably, a positioning groove is provided in the air inlet cylinder, a boss is provided on the side of the pre-swirl nozzle close to the air inlet cylinder, and the positioning groove and the boss are snap-fitted to each other. The pre-swirl nozzle is snap-fitted to the end of the air inlet cylinder close to the sealing cylinder, which can limit the radial displacement of the pre-swirl nozzle during operation. At the same time, the air inlet cylinder and the sealing cylinder are simultaneously fitted with the first ring and the second ring of the pre-swirl nozzle, which limits the axial movement of the pre-swirl nozzle.

Preferably, an intake cylinder sealing ring is provided on the intake cylinder, a sealing cylinder sealing ring is provided on the sealing cylinder, the intake cylinder sealing ring is arranged on the side of the pre-swirl nozzle away from the sealing cylinder, the sealing cylinder sealing ring is arranged on the side of the pre-swirl nozzle away from the intake cylinder, the intake cylinder sealing ring includes a first sealing ring and a second sealing ring, a second air outlet is provided in the intake cylinder, the second air outlet includes an inlet and an outlet, and the outlet is arranged between the first sealing ring and the second sealing ring. The toothed structure of the sealing ring cooperates with the intermediate shaft, and the sealing ring and the intermediate shaft are filled with cold air, and the entry of external high-temperature gas is isolated by the filled cold air. In addition to the air outlet groove, a second air outlet hole is also provided in the air intake cylinder. The aperture of the second air outlet hole is smaller than that of the air outlet groove to ensure that most of the cold air in the air intake cylinder is accelerated and discharged through the pre-swirl nozzle in the air outlet groove, thereby being transmitted to the cooling passage at the rear. A part of the cold air in the second air outlet hole moves away from the sealing cylinder, and a part moves close to the sealing cylinder, respectively filling the first sealing ring and the second sealing ring, wherein the first sealing ring and the internal cold air can effectively prevent the entry of external high-temperature gas, and the second sealing ring and the internal cold air can play a role of secondary protection. At the same time, the movement direction of the cold air in the second sealing ring is close to the sealing cylinder, which can guide the cold air discharged from the pre-swirl nozzle, avoid part of the cold air discharged from the pre-swirl nozzle from entering the second sealing ring to cause the loss of cold air, improve the overall utilization rate of the cold air, and provide a boost for the cold air discharged from the pre-swirl nozzle to approach the sealing cylinder.

Preferably, the first sealing ring is arranged on the side of the second sealing ring away from the pre-swirl nozzle, and the outlet is closer to the second sealing ring than the inlet. The entire second air outlet is inclined, and the outlet is closer to the second sealing ring, which can effectively guide the cold air and transmit the cold air to the second sealing ring. At the same time, due to the small spacing between the sealing rings, the amount of cold air in the second air outlet is greater than the amount of cold air transmitted in the second sealing ring, and the excess cold air that does not pass through the second sealing ring will enter the first sealing ring in the reverse direction. On the basis of ensuring the sealing performance of the first sealing ring, the cold air flow velocity and flow rate in the second sealing ring are accelerated to avoid the loss of cold air. At the same time, the high flow rate of cold air in the second sealing ring is also conducive to the transmission of cold air in the cooling channel of the pre-swirl nozzle; at the same time, in order to avoid the turbulence of the air flow, the second air outlet can be provided with two outlets, one outlet is inclined toward the second sealing ring, and the other outlet is inclined toward the first sealing ring, which has a good guiding effect on the cold air. At the same time, the caliber of the outlet can be smaller than the caliber of the inlet, which has an acceleration effect on the cold air, and at the same time improves the sealing effect and guiding effect.

Preferably, the pre-swirl nozzle includes a No. 1 ring close to the air inlet cylinder and a No. 2 ring away from the air inlet cylinder, and a plurality of nozzle channels are arranged between the No. 1 ring and the No. 2 ring. The outer ring radius of the No. 2 ring is R1, and the inner ring radius is R2. The outer ring radius of the No. 1 ring is r1, and the inner ring radius is r2, and R1＞r1, R2＞r2. The radii of the No. 1 ring and the No. 2 ring of the pre-swirl nozzle are set differently. Compared with the No. 1 ring and the No. 2 ring of the same radius, the pre-swirl nozzle has a larger orifice area, which can obtain better air intake and exhaust effects. At the same time, the outer ring and the inner ring of the No. 2 ring are larger than the inner ring and the outer ring of the No. 1 ring. As shown in FIG5, the air inlet of the pre-swirl nozzle faces the air intake direction of the air inlet cylinder, and the air outlet of the pre-swirl nozzle faces the sealing cylinder direction. In this way, the airflow can be collected, accelerated, and discharged more efficiently, and the angle between the discharged gas and the discharged gas from the second sealing ring becomes smaller, which reduces The interference between the two air flows can be better transmitted to the cooling channel at the rear; as shown in Figure 6, the orifice planes of the air inlet and the air outlet of the pre-swirl nozzle can also be set to be concave, which can expand the area and have a better guiding effect on the airflow, making the air intake and outlet smoother, reducing the loss of airflow during air intake and outlet, and a guide arc surface is provided on the part of the pre-swirl nozzle located in the air intake cavity, which can gather the airflow and transmit it to the air inlet, avoid the loss of airflow, and reduce the turbulence of airflow. This scheme achieves the second invention purpose of the present invention.

Preferably, the nozzle channel includes a lower nozzle opening close to the intermediate shaft and an upper nozzle opening far from the intermediate shaft, and in the axial direction of the intermediate shaft, the distance between the lower nozzle opening and the sealing cylinder is smaller than the distance between the upper nozzle opening and the sealing cylinder. The lower nozzle opening is closer to the sealing cylinder, so that the airflow in the nozzle channel flows more toward one side of the sealing cylinder, so that the speed of the cold air in the axial direction of the intermediate shaft is faster, and the loss of the cold air speed in the radial direction is reduced.

The beneficial effects of the present invention are as follows:

(1) The cold air is guided by the pre-swirl nozzle to avoid turbulent airflow inside the device, thereby improving the utilization rate of the cold air and the cooling quality of the entire device;

(2) The cold air discharged from the second air outlet is divided into two parts, which creates double protection and isolates the erosion of high-temperature air from the outside. At the same time, the cold air flowing in the second sealing ring can guide the cold air discharged from the pre-swirl nozzle, thereby improving the utilization efficiency of the cold air;

(3) The second air outlet hole is set obliquely or bifurcated to effectively utilize the flexibility of the airflow to produce directional discharge, reduce the useless consumption of cold air between the first sealing ring and the second sealing ring, and accelerate the airflow by reducing the air outlet, thereby producing better sealing and guiding effects;

(4) The inner and outer radii of the No. 1 and No. 2 rings of the pre-swirl nozzle are different, which can expand the air inlet and outlet areas, improve the cold air transmission efficiency, and change the direction of the air inlet and outlet surfaces to better cater to the transmission direction of the airflow;

(5) The obliquely arranged nozzle channel can better increase the axial flow velocity of the cooling air, better adapt to the cooling channel, and reduce the loss of cooling air in the radial direction;

(6) The pre-swirl nozzle is connected to the air inlet cylinder by a boss and a positioning groove, and the end face away from the air inlet cylinder is fitted with the end face of the sealing cylinder, which simplifies the positioning and installation structure of the pre-swirl nozzle, facilitates disassembly and replacement, reduces system parts, and improves the stability of system operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a cross-sectional view of the pre-swirl nozzle in Example 1. FIG.

FIG. 3 is a partial schematic diagram of point A in FIG. 1 .

FIG. 4 is a schematic structural diagram of Embodiment 2.

FIG5 is a schematic structural diagram of Example 3.

FIG. 6 is a schematic structural diagram of Embodiment 4.

In the figure: 1. intermediate shaft, 2. intake cylinder, 21. outlet groove, 22. positioning groove, 23. second outlet hole, 231. inlet, 232. outlet, 3. pre-swirl nozzle, 31. No. 1 ring, 32. No. 2 ring, 33. nozzle channel, 331. lower nozzle opening, 332. upper nozzle opening, 34. boss, 4. sealing cylinder, 5. intake cylinder sealing ring, 51. first sealing ring, 52. second sealing ring, 6. sealing cylinder sealing ring, 7. guide arc surface, 8. moving blade.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

Embodiment 1:

As shown in Figures 1 and 2, a high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle includes a rotatable intermediate shaft 1 and an air intake cylinder 2. The air intake cylinder 2 is sleeved on the outside of the intermediate shaft 1 with a gap, and an air outlet groove 21 is provided on the side of the air intake cylinder 2 close to the intermediate shaft 1, and a pre-swirl nozzle 3 is provided in the air outlet groove 21; a sealing cylinder 4 is connected to the end of the air intake cylinder 2 close to the turbine disc, and the pre-swirl nozzle 3 is arranged between the air intake cylinder 2 and the sealing cylinder 4.

The pre-swirl nozzle 3 provided in the air supply system is located between the intake cylinder 2 and the intermediate shaft 1. After the cold air enters the intake cylinder 2, the cold air is transmitted to the gap between the intermediate shaft 1 and the intake cylinder 2 through the pre-swirl nozzle 3 provided in the air outlet groove 21. The gap extends all the way through the entire turbine disk device, so the cold air can be transmitted along the gap to the inside of each turbine disk. Therefore, the gap is also a cooling passage for the entire device, especially for the parts such as the moving blades 8 that directly contact the combustion gas, to effectively cool down the parts, so as to avoid the internal device from being subjected to excessive temperature and reducing its service life. At the same time, a plurality of nozzle channels 33 are provided in the pre-swirl nozzle 3 for transmitting cold air. Since the intake cylinder 2 is fixed The intermediate shaft 1 rotates around the axis of rotation, so the nozzle channel 33 inside the pre-swirl nozzle 3 is oriented in the direction of rotation, which can transmit the cold air closer to the surface of the central axis. The nozzle channel 33 has a good guiding effect during operation. At the same time, the diameter of the air inlet of the pre-swirl nozzle 3 is generally larger than the diameter of the air outlet and has an accelerating effect on the cold air. The sealing cylinder 4 is closer to the turbine disk than the intake cylinder 2. The pre-swirl nozzle 3 is arranged between the intake cylinder 2 and the sealing cylinder 4, which can effectively reduce the loss stroke of the accelerated cold air during the transmission process. The pre-swirl nozzle 3 is arranged between the intake cylinder 2 and the sealing cylinder 4 for the convenience of subsequent replacement of the pre-swirl nozzle 3.

As shown in Fig. 3, a positioning groove 22 is provided in the air inlet cylinder 2, and a boss 34 is provided on the side of the pre-swirl nozzle 3 close to the air inlet cylinder 2, and the positioning groove 22 is engaged with the boss 34. The pre-swirl nozzle 3 is engaged with the end of the air inlet cylinder 2 close to the sealing cylinder 4, which can limit the radial deviation of the pre-swirl nozzle 3 during operation. At the same time, the air inlet cylinder 2 and the sealing cylinder 4 are simultaneously in contact with the first ring 31 and the second ring 32 of the pre-swirl nozzle 3, which limits the axial movement of the pre-swirl nozzle 3.

As shown in Figures 1 and 3, an intake cylinder sealing ring 5 is provided on the intake cylinder 2, and a sealing cylinder sealing ring 6 is provided on the sealing cylinder 4. The intake cylinder sealing ring 5 is arranged on the side of the pre-swirl nozzle 3 away from the sealing cylinder 4, and the sealing cylinder sealing ring 6 is arranged on the side of the pre-swirl nozzle 3 away from the intake cylinder 2. The intake cylinder sealing ring 5 includes a first sealing ring 51 and a second sealing ring 52. A second air outlet 23 is provided in the intake cylinder 2. The second air outlet 23 includes an inlet 231 and an outlet 232. The outlet 232 is arranged between the first sealing ring 51 and the second sealing ring 52. The toothed structure of the sealing ring cooperates with the intermediate shaft 1, and the space between the sealing ring and the intermediate shaft 1 is filled with cold air, which isolates the entry of high-temperature gas from the outside. In addition to the outlet groove 21, the air inlet cylinder 2 is also provided with a second outlet hole 23. The aperture of the second outlet hole 23 is smaller than that of the outlet groove 21, so as to ensure that most of the cold air in the air inlet cylinder 2 is accelerated and discharged through the pre-swirl nozzle 3 in the outlet groove 21, so as to be transferred to the cooling passage at the rear, and part of the cold air in the second outlet hole 23 moves away from the sealing cylinder 4, and part of the cold air moves close to the sealing cylinder 4, respectively filling The first sealing ring 51 and the second sealing ring 52 are repelled, wherein the first sealing ring 51 and the internal cold air can effectively prevent the entry of external high-temperature gas, and the second sealing ring 52 and the internal cold air can play a role of secondary protection. At the same time, the movement direction of the cold air in the second sealing ring 52 is close to the sealing cylinder 4, which can guide the cold air discharged from the pre-swirl nozzle 3 to avoid part of the cold air discharged from the pre-swirl nozzle 3 from entering the second sealing ring 52 and causing the loss of cold air, thereby improving the overall utilization rate of the cold air and providing a boost for the cold air discharged from the pre-swirl nozzle 3 to be close to the sealing cylinder 4.

The assembly and working process of the high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle in the present embodiment is as follows: In the present embodiment, the pre-swirl nozzle 3 is first engaged in the positioning groove 22 at the end of the intake cylinder 2 through the boss 34, and then the sealing cylinder 4 is bolted to the intake cylinder 2, and the intermediate shaft 1 is arranged in the cavity of the intake cylinder 2 and the sealing cylinder 4. At the same time, a second air outlet is arranged on the left side of the pre-swirl nozzle 3, and the outlet of the second air outlet is arranged between the first sealing ring 51 and the second sealing ring 52. During operation, cold air is transported to the intake cylinder 2 through an external cold air source, and a large part of the cold air is transmitted to the space between the intake cylinder 2 and the intermediate shaft 1 through the nozzle channel 33 in the pre-swirl nozzle 3. Cooling channel, another small part of the cold air enters between the first sealing ring 51 and the second sealing ring 52 through the second air outlet 23, which is used to isolate the high-temperature air from the outside, wherein the cold air in the second sealing ring 52 moves toward the sealing cylinder 4, guiding the gas discharged by the pre-swirl nozzle 3, and then most of the cold air enters the sealing cylinder 4 to cool down the turbine disks at various levels at the rear; during the working process, the intermediate shaft 1 is always in a rotating state, while the intake cylinder 2, the sealing cylinder 4 and the pre-swirl nozzle 3 are all in a stationary state, the nozzle channel 33 is offset in the direction of rotation, and the pre-swirl direction of the cold air is the same as the rotation direction of the intermediate shaft 1, thereby improving the cooling quality and utilization rate of the cold air.

Embodiment 2:

As shown in Figure 4, different from Example 1, in this embodiment, the first sealing ring 51 is arranged on the side of the second sealing ring 52 away from the pre-swirl nozzle 3, and the outlet 232 is closer to the second sealing ring 52 than the inlet 231. In order to avoid airflow turbulence, the second air outlet 23 is provided with two outlets 232, one outlet 232 is inclined toward the second sealing ring 52, and the other outlet 232 is inclined toward the first sealing ring 51, which has a good guiding effect on the cold air. At the same time, the caliber of the outlet 232 can be smaller than the caliber of the inlet 231, which has an acceleration effect on the cold air and improves the sealing effect and the guiding effect.

Embodiment 3:

As shown in FIG5 , different from Example 1, the pre-swirl nozzle 3 in this embodiment includes a No. 1 ring 31 close to the side of the air inlet cylinder 2 and a No. 2 ring 32 away from the side of the air inlet cylinder 2, and a plurality of nozzle channels 33 are arranged between the No. 1 ring 31 and the No. 2 ring 32. The outer ring radius of the No. 2 ring 32 is R1, and the inner ring radius is R2. The outer ring radius of the No. 1 ring 31 is r1, and the inner ring radius is r2. R1＞r1, R2＞r2. The radii of the No. 1 ring 31 and the No. 2 ring 32 of the pre-swirl nozzle 3 are set differently. Compared with the No. 1 ring 31 and the No. 2 ring 32 of the same radius, the pre-swirl nozzle 3 has a larger orifice area, which can obtain better air intake and air outlet effects. At the same time, the outer ring and the inner ring of the No. 2 ring 32 are larger than the inner ring and the outer ring of the No. 1 ring 31. The air inlet of the pre-swirl nozzle 3 faces the air intake direction of the air intake cylinder 2, and the air outlet of the pre-swirl nozzle 3 faces the sealing cylinder 4. In this way, the airflow can be collected, accelerated, and discharged more efficiently, and the angle between the discharged gas and the discharged gas of the second sealing ring 52 becomes smaller, which reduces the interference between the two airflows and can be better transmitted to the cooling channel at the rear.

Embodiment 4:

As shown in Figure 6, different from Example 1, the orifice planes of the air inlet and the air outlet of the pre-swirl nozzle 3 in this embodiment can also be set to be concave, which can expand the area and have a better guiding effect on the airflow, making the air intake and outlet smoother, reducing the loss of the airflow during the air intake and outlet, and a guide arc surface 7 is provided on the part of the pre-swirl nozzle 3 located in the air intake cavity, which can gather the airflow to the air inlet and transmit it to the air inlet, avoid the loss of the airflow, and reduce the turbulence of the airflow; the nozzle channel 33 includes a lower nozzle opening 331 close to the intermediate shaft 1 and an upper nozzle opening 332 away from the intermediate shaft 1, and the lower nozzle opening 331 is closer to the sealing cylinder 4 than the upper nozzle opening 332; the lower nozzle opening 331 is closer to the sealing cylinder 4, so that the airflow in the nozzle channel 33 flows more toward the side of the sealing cylinder 4, so that the speed of the cold air in the axial direction of the intermediate shaft 1 is faster, reducing the loss of the cold air speed in the radial direction.

In addition to the above-mentioned embodiments, within the scope disclosed in the claims and the specification of the present invention, the technical features of the present invention can be reselected and combined to form new embodiments, which can be achieved by those skilled in the art without creative work. Therefore, these embodiments that are not described in detail in the present invention should also be regarded as specific embodiments of the present invention and within the protection scope of the present invention.

Claims (6)

1. A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle, comprising a rotatable intermediate shaft (1), characterized in that it also comprises an air inlet cylinder (2), the air inlet cylinder (2) is sleeved outside the intermediate shaft (1) and a gap is left between the air inlet cylinder (2) and the intermediate shaft (1), the air inlet cylinder (2) is provided with an air outlet groove (21) on the side close to the intermediate shaft (1), the air outlet groove (21) is engaged with a pre-swirl nozzle (3), the pre-swirl nozzle (3) comprises a first ring (31) close to the side of the air inlet cylinder (2) and a second ring (32) away from the side of the air inlet cylinder (2), a plurality of nozzle channels (33) are provided between the first ring (31) and the second ring (32), the outer ring radius of the second ring (32) is R1, and the inner ring radius is R2, the outer ring radius of the first ring (31) is r1, and the inner ring radius is r2, wherein R1>r1, R2>r2. 2. A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle according to claim 1, characterized in that the air inlet cylinder (2) is connected to a sealing cylinder (4) at one end close to the turbine disc, and the pre-swirl nozzle (3) is arranged between the air inlet cylinder (2) and the sealing cylinder (4). 3. A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle according to claim 2, characterized in that a positioning groove (22) is provided in the air intake cylinder (2), a boss (34) is provided on the side of the pre-swirl nozzle (3) close to the air intake cylinder (2), and the positioning groove (22) and the boss (34) are snap-fitted and connected. 4. A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle according to claim 2, characterized in that an intake cylinder sealing ring (5) is provided on the intake cylinder (2), and a sealing cylinder sealing ring (6) is provided on the sealing cylinder (4), the intake cylinder sealing ring (5) is arranged on the side of the pre-swirl nozzle (3) away from the sealing cylinder (4), and the sealing cylinder sealing ring (6) is arranged on the side of the pre-swirl nozzle (3) away from the intake cylinder (2), the intake cylinder sealing ring (5) includes a first sealing ring (51) and a second sealing ring (52), and a second air outlet (23) is provided in the intake cylinder (2), the second air outlet (23) includes an inlet (231) and an outlet (232), and the outlet (232) is arranged between the first sealing ring (51) and the second sealing ring (52). 5. A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle according to claim 4, characterized in that the first sealing ring (51) is arranged on the side of the second sealing ring (52) away from the pre-swirl nozzle (3), and the outlet (232) is closer to the second sealing ring (52) than the inlet (231). 6. A high-efficiency turbine disc cavity air supply structure with a pre-swirl nozzle according to claim 1, characterized in that the nozzle channel (33) includes a lower nozzle opening (331) close to the intermediate shaft (1) and an upper nozzle opening (332) away from the intermediate shaft (1), and in the axial direction of the intermediate shaft (1), the distance between the lower nozzle opening (331) and the sealing cylinder (4) is smaller than the distance between the upper nozzle opening (332) and the sealing cylinder (4).