Turbofan engine based on multi-stage fan

Abstract

The invention relates to a turbofan engine based on a multi-stage fan, which belongs to the technical field of aviation turbofan engines and comprises an inner duct, an outer duct, a high-pressure compressor system, a low-pressure compressor system, a high-pressure turbine, a low-pressure turbine and a multi-stage fan module. The high-pressure turbine drives the high-pressure compressor through the first transmission shaft, and the low-pressure turbine drives the low-pressure compressor and the multi-stage fan module through the second transmission shaft. And the multi-stage fan module comprises at least three stages of fans, transmits power and performs speed regulation and direction conversion through a gear set arranged on a second transmission shaft, so that the rotation directions of the odd-stage fans and the even-stage fans are opposite, and the rotation speeds of the odd-stage fans and the even-stage fans meet a certain proportional relation. The thrust load of the fan is dispersed to multiple stages of fan blades, so that the load of the fan blades is effectively reduced, the total thrust and the propulsive efficiency of the engine are improved, and meanwhile, the noise is favorably reduced.

Description

Technical Field

[0001] This invention belongs to the field of aviation turbofan engine technology, specifically relating to a turbofan engine based on a multi-stage fan. Background Technology

[0002] As the core power unit of an aircraft, the performance of the aero-engine directly affects the performance of the aircraft. Improving the thrust and thrust-to-weight ratio of the engine, enhancing operational stability, and reducing noise are continuous goals pursued in the field of aero-engines.

[0003] Existing turbofan engines primarily rely on a large, single-stage fan driven by a single shaft for their bypass thrust. In this architecture, the fan is designed and driven as a single component, and its technological optimization mainly focuses on the blade profile, materials, and structure of the single-stage blades. Structural optimization schemes that involve multi-stage, grouped components within the fan and achieve deep aerodynamic coupling have not become mainstream. Existing multi-stage fan designs, deviating from the classic turbofan configuration and lacking a clear internal and external bypass duct separation structure, result in airflow organization and structural layouts significantly different from combustion-driven turbofan engines. These engines can only be driven by electric motors, resulting in lower power density, lower thrust, and the inability to directly transplant fuel-powered applications.

[0004] Therefore, since the bypass thrust is highly dependent on the single-stage fan, the fan bears an extremely high aerodynamic load, which makes it difficult for the fan to operate continuously near the optimal efficiency point, increases the risk of airflow separation, and limits the improvement of total thrust; at the same time, the high load also makes the fan the main source of noise. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a turbofan engine based on a multi-stage fan. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a turbofan engine based on a multi-stage fan, characterized in that it includes: an inner duct, an outer bypass duct, a high-pressure compressor system, a low-pressure compressor system, a high-pressure turbine, a low-pressure turbine, and a multi-stage fan module; wherein, the high-pressure turbine drives the high-pressure compressor system via a first drive shaft, and the low-pressure turbine drives the low-pressure compressor system and the multi-stage fan module via a second drive shaft; the multi-stage fan module includes at least three stages of fans; a gear set is provided between the second drive shaft and the multi-stage fan module, the gear set being used to reverse the direction of the unidirectional rotational power output from the second drive shaft, such that the rotation directions of adjacent two-stage fans are opposite.

[0006] In one embodiment of the present invention, the multi-stage fan module includes a multi-stage fan arranged coaxially in series along the airflow direction.

[0007] In one embodiment of the present invention, the fan in the multi-stage fan module includes an odd-numbered fan and an even-numbered fan, wherein the odd-numbered fans rotate in the same direction, the even-numbered fans rotate in the same direction, the odd-numbered fans rotate in opposite directions to the even-numbered fans, and the rotation speeds of the odd-numbered fans and the even-numbered fans satisfy a certain proportional relationship.

[0008] In one embodiment of the present invention, the high-pressure compressor system includes a high-pressure compressor, the low-pressure compressor system includes a low-pressure compressor, and the low-pressure compressor and the high-pressure compressor are arranged sequentially in the airflow direction within the inner duct.

[0009] In one embodiment of the present invention, the high-pressure compressor and the high-pressure turbine are connected via the first drive shaft; the low-pressure compressor and the low-pressure turbine are connected via the second drive shaft.

[0010] In one embodiment of the present invention, the first drive shaft and the second drive shaft rotate independently.

[0011] In one embodiment of the present invention, the gear set is disposed on the second transmission shaft and includes at least two sets of reducers. The reducers are connected to any stage of the fan and are used to make the rotation directions of adjacent two stages of the fan opposite.

[0012] In one embodiment of the present invention, the reducer corresponds one-to-one with the number of fans that need to be driven in the multi-stage fan, and the input end of each reducer is connected to the second drive shaft, and the output end is connected to the fan.

[0013] In one embodiment of the present invention, the outer bypass duct is cylindrical, and the inner bypass duct, high-pressure compressor system, low-pressure compressor system, high-pressure turbine, low-pressure turbine, gear set and multi-stage fan module are all disposed in the outer bypass duct, and the inlet of the inner bypass duct starts downstream of the multi-stage fan module.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention relates to a multi-stage fan-based turbofan engine. By incorporating a multi-stage fan module containing at least three stages of fans and employing a gear set to transmit and redirect the power from the low-pressure turbine, the total thrust of the engine is distributed across the multiple fan stages. This significantly reduces the aerodynamic load on each fan stage, enabling operation closer to its peak efficiency point and effectively reducing the risk of airflow separation. Under the same size constraints, a higher total pressure ratio and total thrust are achieved. Furthermore, thrust distribution also means that noise sources are dispersed, contributing to noise reduction.

[0015] The turbofan engine based on multi-stage fans of this invention can more effectively straighten the swirling flow generated by the preceding stage by having each fan rotate in opposite directions, reducing the circumferential velocity and making the airflow closer to the ideal axial flow. This results in less kinetic energy loss in the exit airflow and further improves propulsion efficiency. In addition, the multi-stage fans also help to disperse and counteract the gyroscopic torque generated by high-speed rotation, improving propulsion efficiency and enhancing the engine's handling stability during maneuvering flight.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a turbofan engine based on a multi-stage fan, provided by an embodiment of the present invention.

[0018] Reference numerals: 100-Inner duct; 200-Outer bypass duct; 300-High pressure compressor system; 400-Low pressure compressor system; 500-High pressure turbine; 600-Low pressure turbine; 700-Gear set; 800-Multi-stage fan module. Detailed Implementation

[0019] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following describes in detail a turbofan engine based on a multi-stage fan according to the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0020] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0021] Example 1 like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a turbofan engine based on a multi-stage fan, provided by an embodiment of the present invention.

[0022] In this embodiment, the turbofan engine based on a multi-stage fan includes: an inner duct 100, an outer bypass duct 200, a high-pressure compressor system 300, a low-pressure compressor system 400, a high-pressure turbine 500, a low-pressure turbine 600, a gear set 700, and a multi-stage fan module 800. The outer bypass duct 200 is cylindrical. The inner duct 100, high-pressure compressor system 300, low-pressure compressor system 400, high-pressure turbine 500, low-pressure turbine 600, gear set 700, and multi-stage fan module 800 are all disposed within the outer bypass duct 200. The inlet of the inner duct 100 begins downstream of the multi-stage fan module 800.

[0023] Specifically, the high-pressure turbine 500 drives the high-pressure compressor system 300 through the first drive shaft, and the low-pressure turbine 600 drives the low-pressure compressor system 400 and the multi-stage fan module 800 through the second drive shaft; the multi-stage fan module 800 includes at least three stages of fans; a gear set 700 is provided between the second drive shaft and the multi-stage fan module 800, and the gear set 700 is used to transmit and change the direction of the unidirectional rotational power output by the second drive shaft, so that the rotation directions of adjacent two-stage fans are opposite.

[0024] It is worth noting that the multi-stage fan structure can accommodate larger airflow, making it particularly suitable for high-bypass-ratio engines. By optimizing the number and size of the fan blades, more air enters the outer bypass duct 200. The airflow within the outer bypass duct 200 is accelerated through multiple stages before being discharged, becoming the main source of total thrust. Simultaneously, based on the load distribution across multiple fan stages, the span of a single fan rotor is shorter, the critical speed is lowered, and the response speed is faster. Furthermore, because thrust is distributed across more fan blades, the lift pulsations (the main noise source) generated by each fan stage are weaker, and noise energy is dispersed across more frequencies, contributing to noise reduction.

[0025] In one optional embodiment, the multi-stage fan module 800 includes four, five, six or more stages of fans arranged coaxially in series along the airflow direction; wherein the fans in the multi-stage fan module 800 include odd-numbered fans and even-numbered fans, the odd-numbered fans rotate in the same direction, the even-numbered fans rotate in the same direction, and the odd-numbered fans rotate in opposite directions to the even-numbered fans.

[0026] For example, the multi-stage fan module 800 has four fan stages. The first and third stage fans rotate in the same direction, the second and fourth stage fans rotate in the same direction, and the first stage fan rotates in the opposite direction to the second stage fan, thus forming a multi-stage counter-rotation. This multi-stage counter-rotation has multiple fan blades connected in series, each stage performing work on the air, accelerating it progressively. The stage load is relatively low, allowing each fan stage to operate near its highest efficiency point. Furthermore, by matching the speeds of the multiple fan stages, turbulence is effectively reduced, resulting in highly efficient operation of the multi-stage fans. This significantly improves the overall propulsion efficiency of the engine. At the same fuel consumption rate, the gear set 700 matches the speeds of the odd-numbered and even-numbered fan stages, and by ensuring a certain proportional relationship between their speeds, greater thrust can be generated, further improving the overall propulsion efficiency of the engine.

[0027] Understandably, a higher number of fan stages results in a more even load distribution and the ability to handle greater thrust, but this increases structural complexity. The number of fan stages in the multi-stage fan module 800 can be determined based on thrust requirements and power input; this embodiment does not impose such a limitation. Furthermore, the reduction ratio configuration of the first and second reducers matches the rotational speeds of odd-numbered and even-numbered fan stages, allowing both stages to operate near their highest efficiency points. The actual reduction ratio configuration is a standard technique in aero-engine transmission system design; those skilled in the art can determine the specific ratio based on the fan's aerodynamic design objectives, such as the optimal efficiency point speeds of each stage, and the transmission system layout; therefore, it is not elaborated upon.

[0028] In one optional embodiment, the high-pressure compressor system 300 includes a high-pressure compressor, and the low-pressure compressor system 400 includes a low-pressure compressor. The low-pressure compressor and the high-pressure compressor are arranged sequentially in the airflow direction within the inner duct 100. The high-pressure compressor is connected to the high-pressure turbine 500 via a first drive shaft, and the low-pressure compressor is connected to the low-pressure turbine 600 via a second drive shaft. The first drive shaft and the second drive shaft rotate independently.

[0029] In an optional embodiment, the gear set 700 is disposed on the second drive shaft and includes at least two sets of reducers. The reducers are connected to any stage of the fan and are used to make the rotation directions of adjacent two stages of the fan opposite, and to make the speeds of the odd-numbered stage fans and the even-numbered stage fans satisfy a certain proportional relationship.

[0030] For example, the reducer can be a planetary gear reduction and reversing mechanism, which is disposed between two adjacent fan stages to change the rotation direction of one of the fan stages and to make the speeds of the odd-numbered and even-numbered fan stages satisfy a certain proportional relationship. Specifically, the multi-stage fan module 800 has four fan stages, where the first-stage fan and the third-stage fan rotate in the same direction, and the second-stage fan and the fourth-stage fan rotate in the same direction. Their speeds are matched by a gear set 700. Simultaneously, driven by the first and second drive shafts, the first-stage fan rotates in the opposite direction to the second-stage fan, thus forming a multi-stage counter-rotation.

[0031] Furthermore, the planetary gear reduction and reversing mechanism corresponds one-to-one with the number of fans requiring reversing drive in a multi-stage fan system, such as odd-numbered or even-numbered fan stages. The input end of each planetary gear reduction and reversing mechanism is connected to a second drive shaft, and the output end is connected to the corresponding number of fans. Each planetary gear reduction and reversing mechanism can adopt a structure with a fixed planetary carrier, a sun gear input, and a ring gear output, or a structure with a fixed ring gear, a sun gear input, and a planetary carrier output. Additionally, the first and second reducers can also be shock wave reducers; this invention does not impose any limitations on this.

[0032] It is worth noting that by using gear set 700 to receive power from low-pressure turbine 600 and complete the reversal, there is no need to set up an independent power source for each stage fan, which significantly simplifies the layout of the transmission system and improves the reliability of the transmission chain.

[0033] The working principle of the turbofan engine based on multi-stage fans of the present invention is as follows: it includes a multi-stage fan module 800, a compressor system, a combustion chamber, a turbine system, and an exhaust nozzle arranged sequentially along the airflow direction. The high-pressure turbine 500 drives the high-pressure compressor and the odd-numbered stage fans to rotate via a first drive shaft that rotates in reverse, while the low-pressure turbine 600 drives the low-pressure compressor and the even-numbered stage fans to rotate via a second drive shaft that rotates in the forward direction.

[0034] Thus, by gradually increasing the axial velocity of the airflow through a four-stage relay-style work, while reducing aerodynamic losses, a cumulative increase in thrust and efficiency is ultimately achieved. After entering through the duct lip, the airflow flows sequentially through each stage of the fan. The preceding fan performs work on the airflow, initially accelerating it and simultaneously generating a circumferential rotational component. The subsequent fan rotates in the opposite direction, recovering the circumferential rotational kinetic energy of the preceding airflow and converting it into axial thrust, while also continuing to accelerate the airflow. The fans work synergistically through aerodynamic coupling, drawing in a large amount of air and diverting a portion of it to the inner duct 100 (where air sequentially enters the compressor, combustion chamber, and turbine, participating in combustion) and the outer bypass duct 200 (where air does not participate in combustion, is directly accelerated by the fans, and then expelled, generating the main thrust). The outer bypass duct 200 constrains the flow field, reduces induced drag, and stabilizes the airflow, ultimately resulting in a high-speed, high-pressure airflow exiting from the duct outlet to generate continuous thrust.

[0035] To enable those skilled in the art to fully understand and implement this invention, the specific implementation principle of this invention will be further explained below in conjunction with a specific application scenario.

[0036] The multi-stage fan module 800 is located at the very front of the engine. Within this module, the blades of different stages rotate in opposite directions, effectively reducing the blade speed and thus dispersing and counteracting the gyroscopic torque generated by high-speed rotation. This also reduces the counter-torque exerted by the power unit on the aircraft. Therefore, it significantly improves propulsion efficiency and enhances the engine's handling stability during maneuvering flight. The following example uses a four-stage fan, but in actual operation, six, eight, or even more stages can be used.

[0037] Air entering the engine is first accelerated by the multi-stage fan module 800. The multi-stage fan is a key component for the intake and initial thrust increase of the turbofan engine. It adopts a four-stage fan configuration, in which the first and third stages are coaxial and rotate in reverse, while the second and fourth stages are coaxial and rotate in forward. A large amount of air is drawn in by the fan and diverted to the inner duct 100 for combustion, and diverted to the outer bypass duct 200 to generate the main thrust.

[0038] The gear set 700 includes two reducers located between the multi-stage fan module 800 and the compressor system. It is used to transmit and change the direction of the unidirectional rotational power output from the second drive shaft, so that the rotation direction of the odd-numbered fans is opposite to that of the even-numbered fans.

[0039] The combustion chamber, as the area where air and fuel are mixed and burned, is the core area for energy conversion. Fuel is injected into the combustion chamber, mixes with compressed air, and then ignites to produce high-temperature and high-pressure gas.

[0040] This invention achieves increased thrust and propulsion efficiency through a multi-stage fan, the principle of which is as follows: As the airflow passes through the rotating first-stage fan, a negative pressure field is created within the duct, accelerating the inflow of external air. The airflow then passes through the second-stage fan, which rotates in the opposite direction to the first. After the first-stage fan performs its work, the airflow carries circumferential rotational kinetic energy in the same direction as the fan's rotation, resulting in aerodynamic losses. The secondary counter-rotating fan directly receives this rotating airflow; its blade angle of attack matches the airflow's rotation direction, converting the circumferential kinetic energy into axial thrust. It further accelerates the airflow, increasing its pressure and axial velocity, thereby increasing thrust. The airflow then passes through the third-stage fan, which rotates in the opposite direction to the second. Although the airflow has been corrected by the second-stage fan, a small amount of residual circumferential disturbance still exists. The fourth stage effectively reduces this circumferential disturbance.

[0041] On one hand, the third-stage fan continues to absorb the residual circumferential kinetic energy of the airflow discharged from the second-stage fan, converting it entirely into axial thrust, thus focusing all the airflow's energy in the propulsive direction. Since the first two stages of the fan have already achieved initial airflow stabilization, and the third-stage fan also suppresses secondary backflow within the duct, reducing reverse flow losses between stages and ensuring that all airflow is transferred backward, preparing for the acceleration of the fourth-stage fan. Finally, the airflow flows to the fourth-stage fan, which, as the final power unit, rotates in the opposite direction to the third-stage fan. This maximizes the outlet momentum of the airflow and reduces exhaust losses; its blade design incorporates both speed-increasing and rectification functions.

[0042] The fourth-stage fan provides a final acceleration to the high-pressure airflow processed by the third-stage fan and completely eliminates any remaining minute circumferential components through rectification, allowing the airflow to exit in a purely axial manner. Simultaneously, the fourth-stage fan reduces diffusion losses during exhaust, preventing widespread diffusion of the exhaust airflow and ensuring that every unit of airflow energy is efficiently converted into thrust. Each fan stage only bears a portion of the total thrust and also performs a part of the acceleration and circumferential flow reduction function. Therefore, its blade aerodynamic load can be designed to be lower, and the low-load design allows each fan stage to operate near its higher efficiency point. It is understood that the specific blade shape, installation angle, and other aerodynamic and structural design parameters of the fan blades of each stage of the multi-stage fan module 800 of the present invention can be determined and optimized based on the required stage load, flow rate, and efficiency targets, with reference to the existing aerodynamic design theories and engineering methods of aero-engine fans / compressors, and can be implemented with reference to relevant existing technologies, therefore, they are not described in detail.

[0043] This invention achieves airflow efficiency enhancement through the inner bypass duct 100, outer bypass duct 200, and multi-stage fan module 800. The principle is as follows: the airflow in the outer bypass duct 200 is accelerated four times by four stages of fans and then flows to the exhaust nozzle in a stable state; the airflow in the inner bypass duct 100 is pressurized by a high-pressure compressor, combusted in the combustion chamber, drives the turbine to do work, and then flows to the exhaust nozzle. The two types of airflow are mixed and accelerated before being discharged, generating thrust through reaction force. Simultaneously, due to the small airflow disturbance, operating noise and fuel consumption are further reduced.

[0044] The turbofan engine based on multi-stage fans of the present invention has two rotor systems internally. The high-pressure compressor drives the first-stage fan and the third-stage fan to reverse in the same direction under the drive of the high-pressure turbine 500; the low-pressure compressor drives the second-stage fan and the fourth-stage fan to reverse in the same direction under the drive of the low-pressure turbine 600.

[0045] The following is a further explanation of the specific working process of the present invention: After the engine starts, driven by the low-pressure turbine 600 and the high-pressure turbine 500, the four-stage fans rotate at high speed in opposite directions, drawing in a large amount of air from the outside. The air first undergoes initial acceleration and gains kinetic energy through the first-stage fan, then enters the second-stage counter-current fan, where the circumferential rotation of the airflow is corrected and the pressure is increased again. The air then enters the third-stage fan, where it is accelerated again to gain kinetic energy. Finally, the airflow passes through the fourth-stage counter-current fan, where its circumferential rotation is corrected, allowing the airflow to be discharged axially. Simultaneously, the third-stage fan reduces diffusion losses during exhaust, preventing large-scale diffusion after exhaust and ensuring that every unit of airflow energy is efficiently converted into thrust. The airflow is then divided into outer bypass airflow and inner bypass airflow by the splitter ring. The outer bypass airflow flows steadily towards the exhaust nozzle, while the inner bypass airflow enters the low-pressure compressor for compression.

[0046] The airflow entering the inner duct 100 passes through the multi-stage blades of the low-pressure compressor, where its pressure and temperature are initially increased. Simultaneously, the airflow is organized into a stable axial flow, providing uniform intake conditions for the high-pressure compressor. After being compressed by the low-pressure compressor, the airflow enters the high-pressure compressor and is pressurized to the pressure required for combustion. The high-speed rotor of the high-pressure compressor allows the multi-stage blades to deeply compress the airflow, ultimately increasing the air pressure to 20-40 times that of atmospheric pressure and the temperature to 500-600℃. The high density of the high-pressure air allows for more complete combustion of subsequent fuels, releasing more energy.

[0047] The airflow then enters the combustion chamber, where the fuel nozzle atomizes and injects fuel, which mixes thoroughly with the airflow and ignites, forming a high-temperature, high-pressure gas. The gas expands and accelerates, impacting the turbine blades at high speed and driving the high-pressure turbine 500 to rotate at high speed. The high-pressure turbine 500 is rigidly connected to the high-pressure compressor via the first drive shaft, so the rotation of the high-pressure turbine 500 directly drives the high-pressure compressor to operate continuously.

[0048] After the high-pressure turbine 500 has performed work, the gas still retains a significant amount of energy and continues to flow to the low-pressure turbine 600. The gas impacts the blades of the low-pressure turbine 600, driving it to rotate. The low-pressure turbine 600 is connected to the low-pressure compressor and fan via a second drive shaft. Therefore, the rotation of the low-pressure turbine 600 drives the low-pressure compressor and the second and fourth-stage fans to rotate synchronously. Power is transmitted through the gear set 700 and reversed, causing the first and third-stage fans to rotate in opposite directions. During this process, the temperature, pressure, and flow rate of the gas are significantly reduced, and the energy is fully utilized.

[0049] The airflow accelerated by the four-stage fan in the outer bypass duct 200 mixes with the exhaust gas after it has been powered by the turbine in the inner bypass duct 100 at the exhaust nozzle. The mixed airflow is further accelerated under the constraint of the exhaust nozzle and finally discharged from the engine at high speed. The high-speed exhaust creates a velocity difference with the surrounding air, generating forward thrust to propel the aircraft forward. Air in the outer bypass duct 200 that does not participate in combustion is directly accelerated by the fan and discharged, providing continuous thrust for the aircraft.

[0050] The present invention relates to a multi-stage fan-based turbofan engine. By incorporating a multi-stage fan module containing at least three stages of fans and employing a gear set to transmit and redirect the power from the low-pressure turbine, the total thrust of the engine is distributed across the multiple fan stages. This significantly reduces the aerodynamic load on each fan stage, enabling operation closer to its peak efficiency point and effectively reducing the risk of airflow separation. Under the same size constraints, a higher total pressure ratio and total thrust are achieved. Furthermore, thrust distribution also means that noise sources are dispersed, contributing to noise reduction.

[0051] The turbofan engine based on multi-stage fans of this invention can more effectively straighten the swirling flow generated by the preceding stage by having each fan rotate in opposite directions, reducing the circumferential velocity and making the airflow closer to the ideal axial flow. This results in less kinetic energy loss in the exit airflow and further improves propulsion efficiency. In addition, the multi-stage fans also help to disperse and counteract the gyroscopic torque generated by high-speed rotation, improving propulsion efficiency and enhancing the engine's handling stability during maneuvering flight.

[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0053] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A turbofan engine based on a multi-stage fan, characterized in that, include: Inner bypass duct, outer bypass duct, high-pressure compressor system, low-pressure compressor system, high-pressure turbine, low-pressure turbine and multi-stage fan module; The high-pressure turbine drives the high-pressure compressor system via a first drive shaft, and the low-pressure turbine drives the low-pressure compressor system and the multi-stage fan module via a second drive shaft. The multi-stage fan module includes at least three stages of fans; A gear set is provided between the second drive shaft and the multi-stage fan module. The gear set is used to reverse the direction of the unidirectional rotational power output by the second drive shaft, so that the rotation directions of adjacent two stages of the fan are opposite.

2. The turbofan engine based on a multi-stage fan according to claim 1, characterized in that, The multi-stage fan module includes multiple stages of fans arranged coaxially in series along the airflow direction.

3. The turbofan engine based on a multi-stage fan according to claim 2, characterized in that, The multi-stage fan module includes odd-numbered fans and even-numbered fans, wherein the odd-numbered fans rotate in the same direction, the even-numbered fans rotate in the same direction, the odd-numbered fans rotate in opposite directions to the even-numbered fans, and the rotation speeds of the odd-numbered fans and the even-numbered fans satisfy a certain proportional relationship.

4. The turbofan engine based on a multi-stage fan according to claim 1, characterized in that, The high-pressure compressor system includes a high-pressure compressor, and the low-pressure compressor system includes a low-pressure compressor. The low-pressure compressor and the high-pressure compressor are arranged sequentially along the airflow direction within the inner duct.

5. The turbofan engine based on a multi-stage fan according to claim 4, characterized in that, The high-pressure compressor and the high-pressure turbine are connected via the first drive shaft; the low-pressure compressor and the low-pressure turbine are connected via the second drive shaft.

6. The turbofan engine based on a multi-stage fan according to claim 1, characterized in that, The first drive shaft rotates independently of the second drive shaft.

7. The turbofan engine based on a multi-stage fan according to claim 1, characterized in that, The gear set is mounted on the second drive shaft and includes at least two reducers. The reducers are connected to any one of the fan stages and are used to make the rotation directions of adjacent fan stages opposite.

8. The turbofan engine based on a multi-stage fan according to claim 7, characterized in that, The reducer corresponds one-to-one with the number of fans that need to be driven in the multi-stage fan. The input end of each reducer is connected to the second drive shaft, and the output end is connected to the corresponding fan.

9. The turbofan engine based on a multi-stage fan according to claim 1, characterized in that, The outer bypass duct is cylindrical, and the inner bypass duct, high-pressure compressor system, low-pressure compressor system, high-pressure turbine, low-pressure turbine, gear set and multi-stage fan module are all located inside the outer bypass duct. The entrance of the inner bypass duct starts downstream of the multi-stage fan module.

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