阅读说明：本技术 一种间冷式高总压比中涵道涡扇发动机 (Indirect cooling type high-total-pressure-ratio middle duct turbofan engine ) 是由 李泳凡 怀时卫 金海� 刘诗尧 周伟朋 周建超 任东 于 2021-11-03 设计创作，主要内容包括：本申请涉及涡扇发动机领域,为一种间冷式高总压比中涵道涡扇发动机,通过在核心机与轴流式风扇之间设置单级离心式中压压气机,高温内涵道气流从轴流式风扇流出后进入到单级离心式中压压气机内,再由单级离心式中压压气机流出后进入到核心机内,多级低压涡轮通过低压涡轮轴能够带动单级离心式中压压气机同步转动,从而使得轴流式风扇、单级离心式中压压气机和核心机配合能够得到较高的总压比,同时航空发动机内部总体的转子级数较少,布局合理；同时将通过单级离心式中压压气机后的高温内涵通道引入到低温外涵通道处进行热交换,降温后的高温内涵排气能够有效满足核心机的使用需求。(The application relates to the field of turbofan engines, in particular to an indirect cooling type high total pressure ratio middle bypass turbofan engine.A single-stage centrifugal medium pressure air compressor is arranged between a core machine and an axial flow fan, high-temperature inner bypass airflow flows out from the axial flow fan and then enters the single-stage centrifugal medium pressure air compressor, then flows out from the single-stage centrifugal medium pressure air compressor and then enters the core machine, a multi-stage low pressure turbine can drive the single-stage centrifugal medium pressure air compressor to synchronously rotate through a low pressure turbine shaft, so that the axial flow fan, the single-stage centrifugal medium pressure air compressor and the core machine are matched to obtain a higher total pressure ratio, and meanwhile, the total number of rotor stages in the aircraft engine is less and the layout is reasonable; meanwhile, a high-temperature content channel passing through the single-stage centrifugal medium-pressure compressor is introduced to the low-temperature content channel for heat exchange, and the use requirement of the core machine can be effectively met by the high-temperature content exhaust after cooling.)

1. The utility model provides a duct turbofan engine in high total pressure ratio of indirect cooling type, includes high-pressure shafting, low pressure shafting and load machine casket, low pressure shafting is including axial fan (2) of locating the front end, low pressure turbine shaft (17) of passing high pressure shafting, the multistage low pressure turbine (13) of locating the rear end, high pressure shafting is located between axial fan (2) and multistage low pressure turbine (13), low temperature culvert passageway (5) and high temperature culvert passageway (6) are drawn forth to axial fan (2) rear end, and high temperature culvert passageway (6) enter into high pressure shafting in, its characterized in that: the high-temperature bypass type air conditioner is characterized in that a single-stage centrifugal medium-pressure air compressor (7) connected with a low-pressure turbine shaft (17) is arranged between the high-pressure shafting and the axial flow fan (2), the multi-stage low-pressure turbine (13) drives the single-stage centrifugal medium-pressure air compressor (7) to synchronously rotate through the low-pressure turbine shaft (17), high-temperature bypass airflow in a high-temperature bypass channel (6) led out by the axial flow fan (2) passes through the single-stage centrifugal medium-pressure air compressor (7) and then enters a low-temperature bypass channel (5) to exchange heat, and finally is led out from the low-temperature bypass channel (5) to enter the high-pressure shafting, and heat exchange mechanisms enabling the low-temperature bypass channel (5) and the high-temperature bypass channel (6) to exchange heat stably are arranged at heat exchange positions.

2. The indirect-cooled high overall pressure ratio ducted turbofan engine of claim 1 wherein: the heat exchange mechanism comprises an indirect cooling heat exchanger (22), a high-temperature culvert channel (6) forms a circular second annular cavity flow channel (23) between the indirect cooling heat exchanger (22) and a single-stage centrifugal medium-pressure compressor (7), a low-temperature heat exchange channel and a high-temperature heat exchange channel are arranged inside the indirect cooling heat exchanger (22), the high-temperature heat exchange channels are all multiple groups, the multiple groups of high-temperature heat exchange channels are uniformly arranged along the circumferential interval of the indirect cooling heat exchanger (22), the low-temperature heat exchange channel is a whole annular channel and surrounds the high-temperature heat exchange channel, and a sealing structure between the high-temperature heat exchange channel and the low-temperature heat exchange channel is made of heat conduction materials.

3. The indirect-cooled high overall pressure ratio ducted turbofan engine of claim 2 wherein: the intercooling heat exchanger (22) is directly connected with the bearing casing, the cross section of the high-temperature heat exchange channel is in an arch bridge shape, and a valve (20) is arranged on the outer wall of the intercooling heat exchanger (22).

4. The indirect-cooled high overall pressure ratio ducted turbofan engine of claim 2 wherein: the bearing casing comprises an intermediate casing (4) and an inter-turbine casing (12), the intermediate casing (4) is arranged between the axial flow fan (2) and the single-stage centrifugal medium-pressure compressor (7), and the inter-turbine casing (12) is arranged between the high-pressure shaft system and the multi-stage low-pressure turbine (13).

5. The indirect-cooled high total pressure ratio ducted turbofan engine of claim 4 wherein: the single-stage centrifugal medium-pressure compressor (7) is rigidly connected with the low-pressure turbine shaft (17), and a second ball bearing (24) is connected between the single-stage centrifugal medium-pressure compressor (7) and the intermediate casing (4).

6. The indirect-cooled high total pressure ratio ducted turbofan engine of claim 4 wherein: the end part of the low-pressure turbine shaft (17) is provided with a gear transmission device (3), the gear transmission device (3) is connected with the axial flow fan (2), the gear transmission device (3) can enable the axial flow fan (2) to rotate at a rotating speed smaller than that of the low-pressure turbine shaft (17), and the gear transmission device (3) is arranged in the bearing case.

7. The indirect-cooled high total pressure ratio ducted turbofan engine of claim 6 wherein: the gear transmission device (3) comprises a small gear connected with the low-pressure turbine shaft (17), a large gear connected with the axial flow fan (2), and a transmission gear arranged between the small gear and the large gear, wherein the small gear and the large gear are coaxially arranged.

8. The indirect-cooled high total pressure ratio ducted turbofan engine of claim 6 wherein: gear (3) are connected with the fan minor axis of coaxial setting, the fan minor axis includes linkage segment, support section and expansion section, support the section and locate between linkage segment and the expansion section, the diameter of linkage segment is greater than the diameter of supporting the end and links to each other with gear (3), the diameter of expansion section is from supporting section one end to the other end crescent.

9. The indirect-cooled high overall pressure ratio ducted turbofan engine of claim 8 wherein: still including locating air inlet machine casket (1) of axial-flow fan (2) front end, be connected with third roller bearing (26) between air inlet machine casket (1) and the fan minor axis, be connected with third ball bearing (25) between intermediary machine casket (4) and the fan minor axis.

10. The indirect-cooled high overall pressure ratio ducted turbofan engine of claim 1 wherein: the high-temperature culvert channel (6) is arranged between the axial flow fan (2) and the high-pressure shaft system in an S shape, the lowest point of the high-temperature culvert channel (6) is positioned at an inlet of the single-stage centrifugal medium-pressure compressor (7), and the highest point of the high-temperature culvert channel is positioned at a heat exchange position of the low-temperature culvert channel (5).

Technical Field

The application belongs to the turbofan engine field, in particular to a ducted turbofan engine in indirect cooling type high total pressure ratio.

Background

The aero-engine adopts a high total pressure ratio as one of the technical means for achieving the low fuel consumption, in the international range, an advanced core engine with a high-pressure compressor with a high pressure ratio is adopted, then the overall configuration of a 'fan' or a 'fan + pressure stage/medium-pressure compressor' with a limited pressure ratio is selected, and in order to further improve the total pressure ratio, the layout of the medium-pressure compressor with the rotating speed between the fan and the high-pressure compressor is adopted, so that the total pressure ratio is further improved.

The invention relates to an aircraft engine, which aims to rapidly develop a medium bypass ratio turbofan engine with the characteristics of high total pressure ratio, limited outline size, mixed exhaust and the like on the basis of a mature core engine with a high-pressure compressor with relatively low pressure ratio; the mature core engine has lower pressure ratio, poorer temperature resistance and the like due to original design, material selection and the like, so that the application potential of the mature core engine is limited, the mature core engine is used as the core engine of the high total pressure ratio aircraft engine, the overall layout of the whole engine needs to be innovated, the characteristics of the minimum number of stages, the relatively compact space, the stage distribution conforming to mixed exhaust and the like are taken as constraints to realize the higher total pressure ratio of the aircraft engine, and the problems of high temperature rise and the like caused by the high total pressure ratio need to be solved on the overall layout.

The most recent implementations of the present invention are the gear drive technology and three-spool layout technology commonly employed in large and medium bypass ratio turbofan engines, and the simple cooling technology used in gas turbines.

The technical scheme of the traditional gear transmission overall layout is that the overall layout of a low-pressure-ratio single-stage fan, a high-pressure-ratio multistage axial-flow type medium-pressure compressor, a high-pressure-ratio multistage high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine is adopted, when the aircraft engine related to the invention contains a mature core machine of the low-pressure-ratio high-pressure compressor, the pressure ratio is improved by adopting a method for increasing the number of stages of the fan/the medium-pressure compressor, firstly, the number of stages is excessive, secondly, the mature core machine cannot bear high temperature rise caused by the high total pressure ratio, and the gear transmission technology is directly adopted, so that the aircraft engine with the high total pressure ratio is difficult to construct under the background of the invention;

the existing technical scheme of 'three-rotor overall layout' mainly solves the problem of high temperature rise caused by constructing an aeroengine with a high total pressure ratio, so that a mature core machine of the aeroengine related to the invention cannot bear the high temperature rise;

the existing technical scheme of 'simple cooling overall layout of a gas turbine' adopts a liquid working medium as a cooling source, a cooling device is huge, and the structural forms of the cooling source and the cooling device cannot be transplanted to an aeroengine.

The prior art is difficult to solve the requirements of high total pressure ratio, less number of rotor stages and less temperature rise of the aero-engine related to the invention, and needs to be solved by the innovative overall layout of the aero-engine provided by the invention.

Disclosure of Invention

The application aims at providing an indirect cooling type high-total-pressure-ratio middle duct turbofan engine to solve the problems that an aero-engine in the existing design is difficult to realize high-total-pressure-ratio, the number of rotor stages is small, and temperature rise is low.

The technical scheme of the application is as follows: the utility model provides an intermediate cooling type high total pressure ratio bypass turbofan engine, includes high-pressure shafting, low pressure shafting and load machine casket, the low pressure shafting is including the axial-flow fan who locates the front end, passes the low pressure turbine shaft of high pressure shafting, locates the multistage low pressure turbine of rear end, the high pressure shafting is located between axial-flow fan and the multistage low pressure turbine, low temperature culvert passageway and high temperature culvert passageway are drawn forth to the axial-flow fan rear end, and the high temperature culvert passageway enters into the high pressure shafting, be equipped with the single-stage centrifugal medium pressure compressor that links to each other with the low pressure turbine shaft between high pressure shafting and the axial-flow fan, multistage low pressure turbine drives single-stage centrifugal medium pressure compressor synchronous revolution through the low pressure, the high temperature culvert air current in the high temperature culvert passageway that the axial-flow fan was drawn forth passes through single-stage centrifugal medium pressure compressor, then enters into the low temperature culvert passageway and carries out the heat transfer, And finally, the heat exchange part of the low-temperature bypass channel and the high-temperature bypass channel is provided with a heat exchange mechanism which can ensure that the low-temperature bypass channel and the high-temperature bypass channel can stably exchange heat.

Preferably, the heat exchange mechanism comprises an indirect cooling heat exchanger, the high-temperature culvert channel forms a circular second annular cavity flow channel between the indirect cooling heat exchanger and the single-stage centrifugal medium-pressure compressor, a low-temperature heat exchange channel and a high-temperature heat exchange channel are arranged inside the indirect cooling heat exchanger, the high-temperature heat exchange channels are multiple groups, the high-temperature heat exchange channels are uniformly arranged along the circumferential direction of the indirect cooling heat exchanger at intervals, the low-temperature heat exchange channel is an integral annular channel, the low-temperature heat exchange channel surrounds the high-temperature heat exchange channel, and a sealing structure between the high-temperature heat exchange channel and the low-temperature heat exchange channel is made of heat conduction materials.

Preferably, the indirect cooling heat exchanger is directly connected with the bearing casing, the cross section of the high-temperature heat exchange channel is in an arch bridge shape, and a valve is arranged on the outer wall of the indirect cooling heat exchanger.

Preferably, the bearing casing comprises an intermediate casing and an inter-turbine casing, the intermediate casing is arranged between the axial flow fan and the single-stage centrifugal medium-pressure compressor, and the inter-turbine casing is arranged between the high-pressure shaft system and the multi-stage low-pressure turbine.

Preferably, the single-stage centrifugal intermediate-pressure compressor is rigidly connected with the low-pressure turbine shaft, and a second ball bearing is connected between the single-stage centrifugal intermediate-pressure compressor and the intermediate casing.

Preferably, a gear transmission device is arranged at the end part of the low-pressure turbine shaft, the gear transmission device is connected with the axial flow fan, the gear transmission device can enable the axial flow fan to rotate at a rotating speed less than that of the low-pressure turbine shaft, and the gear transmission device is arranged in the bearing casing.

Preferably, the gear transmission device comprises a pinion connected with the low-pressure turbine shaft, a gearwheel connected with the axial flow fan, and a transmission gear arranged between the pinion and the gearwheel, and the pinion and the gearwheel are coaxially arranged.

Preferably, the gear transmission device is connected with a fan short shaft which is coaxially arranged, the fan short shaft comprises a connecting section, a supporting section and an expanding section, the supporting section is arranged between the connecting section and the expanding section, the diameter of the connecting section is larger than that of the supporting end and is connected with the gear transmission device, and the diameter of the expanding section is gradually increased from one end of the supporting section to the other end of the expanding section.

Preferably, the axial flow fan further comprises an air inlet casing arranged at the front end of the axial flow fan, a third roller bearing is connected between the air inlet casing and the fan short shaft, and a third ball bearing is connected between the intermediate casing and the fan short shaft.

Preferably, the high-temperature culvert channel is arranged between the axial flow fan and the high-pressure shafting in an S shape, the lowest point of the high-temperature culvert channel is positioned at an inlet of the single-stage centrifugal medium-pressure compressor, and the highest point of the high-temperature culvert channel is positioned at a heat exchange position of the low-temperature culvert channel.

According to the indirect cooling type high total pressure ratio middle bypass turbofan engine, the single-stage centrifugal middle pressure air compressor is arranged between the core machine and the axial flow fan, high-temperature inner bypass airflow flows out of the axial flow fan and then enters the single-stage centrifugal middle pressure air compressor, the single-stage centrifugal middle pressure air compressor flows out of the single-stage centrifugal middle pressure air compressor and then enters the core machine, the multi-stage low-pressure turbine can drive the single-stage centrifugal middle pressure air compressor to synchronously rotate through the low-pressure turbine shaft, so that the axial flow fan, the single-stage centrifugal middle pressure air compressor and the core machine are matched to obtain a high total pressure ratio, the total number of rotor stages in the aircraft engine is small, and the layout is reasonable; meanwhile, a high-temperature content channel passing through the single-stage centrifugal medium-pressure compressor is introduced to the low-temperature content channel for heat exchange, and the use requirement of the core machine can be effectively met by the high-temperature content exhaust after cooling.

Drawings

In order to more clearly illustrate the technical solutions provided by the present application, the following briefly introduces the accompanying drawings. It is to be expressly understood that the drawings described below are only illustrative of some embodiments of the invention.

FIG. 1 is a schematic diagram of the overall structure of the present application;

FIG. 2 is a schematic view of the structure of the indirect cooling heat exchanger of the present application.

1. An air inlet casing; 2. an axial flow fan; 3. a gear transmission; 4. an intermediary case; 5. a low-temperature culvert channel; 6. a high temperature culvert channel; 7. a single-stage centrifugal medium-pressure compressor; 8. an intercooling heat exchange zone; 9. a high pressure compressor; 10. an annular combustion chamber; 11. a high pressure turbine; 12. an inter-turbine casing; 13. a multi-stage low pressure turbine; 14. an exhaust region; 15. a first roller bearing; 16. a second roller bearing; 17. a low-pressure turbine shaft; 18. a first ball bearing; 19. a first annular cavity flow passage; 20. a shutter; 21. a cross-sectional schematic line; 22. an indirect cooling heat exchanger; 23. a second annular cavity flow passage; 24. a second ball bearing; 25. a third ball bearing; 26. and a third rolling rod bearing.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application.

An indirect cooling type middle-duct turbofan engine with high total pressure ratio is shown in figure 1 and comprises a low-pressure shaft system, a high-pressure shaft system and a force bearing casing. The low-pressure shafting passes through the high-pressure shafting, is also the core machine and is located the both sides of high-pressure shafting, and the low-pressure shafting includes axial fan 2, low-pressure turbine shaft 17 and multistage low-pressure turbine 13, and multistage low-pressure turbine 13 is located the rear portion of high-pressure shafting, and axial fan 2 locates the front portion of high-pressure shafting, and low-pressure turbine shaft 17 sets up with aeroengine central line coaxial and passes the high-pressure shafting.

Multistage low-pressure turbine 13 provides power and drives low-pressure turbine shaft 17 and rotate, and low-pressure turbine shaft 17 drives axial fan 2 and rotates, and 2 rear ends of axial fan set up the low temperature culvert passageway 5 and the high temperature culvert passageway 6 that link to each other with axial fan 2, and low temperature culvert passageway 5 is located the outside of high temperature culvert passageway 6, and axial fan 2 steady operation lets in the outer culvert air current of normal atmospheric temperature, lets in the outer culvert air current of high temperature in the high temperature culvert passageway 6 respectively to low temperature culvert passageway 5. The inner culvert airflow of the high-temperature inner culvert channel 6 enters the high-pressure shaft system and is continuously discharged outwards through the high-pressure shaft system; the bypass airflow flows along the low-temperature bypass passage 5, mixes with the bypass airflow at the exhaust area 14 of the aircraft engine outlet, and then flows out.

The high-pressure shafting comprises a multistage high-pressure compressor 9, an annular combustion chamber 10 and a high-pressure turbine 11, wherein the high-pressure turbine 11 drives the multistage high-pressure compressor 9 to work, high temperature and high pressure are provided to drive the annular combustion chamber 10 to burn, and power output is realized.

Wherein the inlet of the aircraft engine is the front end thereof and the outlet is the rear end thereof.

A single-stage centrifugal medium-pressure compressor 7 is arranged between a high-pressure shaft system and an axial flow fan 2, the single-stage centrifugal medium-pressure compressor 7 is connected with the axial flow fan 2, a multi-stage low-pressure turbine 13 drives the single-stage centrifugal medium-pressure compressor 7 to rotate synchronously through a low-pressure turbine shaft 17, high-temperature bypass airflow in a high-temperature bypass channel 6 led out by the axial flow fan 2 passes through the single-stage centrifugal medium-pressure compressor 7 and then enters a low-temperature bypass channel 5 for heat exchange, and finally is led out from the low-temperature bypass channel 5 and enters the high-pressure shaft system, and heat exchange mechanisms enabling the low-temperature bypass channel 5 and the high-temperature bypass channel 6 to exchange heat stably are arranged at heat exchange positions.

The external air is fed from the front end of the aircraft engine, the multistage axial flow fan 2 works to divide the air flow into an inner culvert air flow and an outer culvert air flow and respectively enter a low-temperature outer culvert channel 5 and a high-temperature inner culvert channel 6, and the inner culvert air flow enters a single-stage centrifugal medium-pressure air compressor 7 to be pressurized and then enters the core machine. Because the single-stage centrifugal medium-pressure compressor 7 and the low-pressure turbine shaft 17 rotate synchronously and have higher rotating speed, the single-stage centrifugal medium-pressure compressor 7 works in the self optimal rotating speed interval, the larger supercharging ratio can be stably realized, the higher total pressure ratio of the aircraft engine is comprehensively realized by combining the axial flow fan 2 and the high-pressure compressor 9 in the mature core machine, and the higher total pressure ratio can fully contain the total pressure loss caused by the bending of the flow channel. Meanwhile, the high total pressure ratio is realized by matching the single-stage centrifugal total pressure compressor with the axial flow fan 2 and the high pressure compressor 9, the number of the integral stages is small, and the interior of the aircraft engine is provided with sufficient space to keep each part at the optimal position.

To the high temperature problem that the high total pressure ratio brought, through in 6 crooked and enter into the low temperature culvert passageway with high temperature culvert passageway for the outer duct air current of normal atmospheric temperature carries out heat transfer cooling with the inner duct air current of high temperature, the inner duct air current after the cooling enters into the first ring chamber runner 19 department of core machine front end, then reentrant core built-in, the inner duct air current after the cooling can satisfy the user demand of core machine, realized expanding the utilization by a wide margin to ripe core machine.

To sum up, this application can be when reaching higher total pressure ratio, aeroengine's progression is less, and inner duct air current temperature is lower, has formed good aeroengine overall layout.

As shown in fig. 1 and 2, preferably, the heat exchange mechanism includes an indirect heat exchanger 22, the high-temperature content channel 6 forms an annular second annular channel 23 between the indirect heat exchanger 22 and the single-stage centrifugal medium-pressure compressor 7, a low-temperature heat exchange channel and a high-temperature heat exchange channel are disposed inside the indirect heat exchanger 22, the high-temperature heat exchange channel is of a tubular structure, the high-temperature heat exchange channels are multiple groups, and the high temperature heat exchange channels are uniformly arranged along the circumference of the indirect cooling heat exchanger 22 at intervals, the low temperature heat exchange channels are integral annular channels, and the low temperature heat transfer passageway encircles the high temperature heat transfer passageway, and the low temperature heat transfer passageway forms intercooling heat transfer region 8 with the similar position of high temperature heat transfer passageway like this and carries out the heat transfer, and the enclosed construction between high temperature heat transfer passageway and the low temperature heat transfer passageway adopts the heat conduction material, and high temperature connotation air current begins to disperse and flow into in each high temperature heat transfer passageway when passing through second ring chamber runner 23.

By arranging the indirect cooling heat exchanger 22, the inner duct airflow and the outer duct airflow can flow in a cross way, so that the heat exchange area of the normal-temperature airflow and the high-temperature airflow is large, and the good heat exchange effect is achieved.

Preferably, a first ball bearing 18 is connected between the high-pressure compressor 9 and the bearing casing, so that the core machine can be stably supported by the intermediate casing, a section is arranged at the high-temperature heat exchange channel through a section schematic line 21, the cross section of the high-temperature heat exchange channel is in an arch bridge shape, namely, an outward convex arc structure, so that the flow path of the culvert air flow entering the high-temperature heat exchange channel is increased, the flow area is increased, and the heat exchange efficiency is improved.

Preferably, the intercooling heat exchanger 22 is provided with a valve 20 on the outer wall of the outer culvert area, and the valve 20 can be opened or closed according to the requirements of foreign matter identification and culvert flow regulation, so as to further improve the adjustability of the overall layout and meet the use requirements of complex environments.

Preferably, the force bearing casing comprises an intermediate casing 4 and an inter-turbine casing 12, the intermediate casing 4 is arranged between the axial flow fan 2 and the single-stage centrifugal medium-pressure compressor 7, the inter-turbine casing 12 is arranged between the high-pressure shafting and the multi-stage low-pressure turbine 13, a second roller bearing 16 is connected between the high-pressure turbine 11 and the inter-turbine casing 12, a first roller bearing 15 is connected between the multi-stage low-pressure turbine 13 and the inter-turbine casing 12, and the first roller bearing 18 is externally provided with a support structure directly connected with the intermediate casing 4 so as to stably support the core machine. The axial flow fan 2, the single-stage centrifugal medium-pressure compressor 7 and the core machine are supported through the intermediate casing 4, the core machine and the multi-stage low-pressure turbine 13 are supported through the inter-turbine casing 12, the space arrangement is reasonable, and the structure is stable. The high-temperature heat exchange channel and the indirect cooling heat exchanger 22 are both directly connected with the intermediate casing 4, and the high-temperature heat exchange channel is provided with an opening communicated with the high-temperature culvert channel 6 so as to ensure the supporting strength of the indirect cooling heat exchanger 22.

Preferably, the single-stage centrifugal intermediate-pressure compressor 7 is rigidly connected to the low-pressure turbine shaft 17, so as to ensure the stability of the transmission between the low-pressure turbine shaft 17 and the single-stage centrifugal intermediate-pressure compressor 7, and the second ball bearing 24 is connected between the single-stage centrifugal intermediate-pressure compressor 7 and the intermediate casing 4, so that the single-stage centrifugal intermediate-pressure compressor 7 can be stably supported by the intermediate casing 4.

Preferably, the end of the low-pressure turbine shaft 17 is provided with a gear transmission device 3, the gear transmission device 3 is connected with the axial flow fan 2, the gear transmission device 3 can enable the axial flow fan 2 to rotate at a rotating speed lower than that of the low-pressure turbine shaft 17, and the gear transmission device 3 is arranged in the bearing casing. The gear transmission device 3 realizes the stable work of the axial flow fan 2 in a rotation speed range which is lower than the rotation speed of the low-pressure turbine shaft 17 and is also the optimal rotation speed range of the gear transmission device by speed reduction transmission, and realizes the difference regulation of the rotation speed while transmitting the load; the gear transmission device 3 is arranged at the bearing casing, so that the gear transmission device can ensure that the gear transmission device is stably supported at a better position.

Preferably, the gear transmission device 3 includes a pinion connected to the low-pressure turbine shaft 17, a gearwheel connected to the axial fan 2, and a transmission gear disposed between the pinion and the gearwheel, the pinion and the gearwheel are coaxially disposed and integrally have a planetary gear structure, and the gear transmission device 3 is prior art and will not be described herein.

Preferably, gear 3 is connected with the fan minor axis of coaxial setting, and the fan minor axis includes linkage segment, support section and expansion section, and the support section is located between linkage segment and the expansion section, and the diameter of linkage segment is greater than the diameter of supporting the end and links to each other with gear 3, and the diameter of expansion section is from supporting section one end to the other end and is crescent. Can stably cooperate with gear 3 through setting up the great linkage segment of diameter, the expansion segment sets up the toper structure and can stably be connected and support with axial-flow fan 2.

Preferably, the air inlet device further comprises an air inlet casing 1 arranged at the front end of the axial flow fan 2, a third roller bearing 26 is connected between the air inlet casing 1 and the fan stub shaft, and a third ball bearing 25 is connected between the intermediate casing 4 and the fan stub shaft. The intermediate case 4 can stably support the short shaft of the fan through the third ball bearing 25, and the air inlet case 1 can stably support the intermediate case 4 and the short shaft of the fan through the third roller bearing 26, so as to ensure the stability of the short shaft of the fan.

Preferably, the high-temperature culvert channel 6 is arranged in an S shape between the axial flow fan 2 and the high-pressure shafting, the lowest point of the high-temperature culvert channel 6 is positioned at the inlet of the single-stage centrifugal medium-pressure compressor 7, and the highest point of the high-temperature culvert channel 6 is positioned at the heat exchange position with the low-temperature culvert channel 5. Through setting up to the high temperature content passageway 6 of S-shaped bend structure, can guarantee can be stable admit air at the single-stage centrifugal middling pressure compressor 7 entrance of lower position, have longer route can carry out stable heat exchange in the low temperature content passageway 5 department of higher position.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.