Damping and noise-reducing duct structure of turbofan engine and duct damping and noise-reducing method thereof

Abstract

The invention discloses a turbofan engine shock absorption and noise reduction duct structure and a duct shock absorption and noise reduction method thereof.An additional J duct is additionally arranged between an outer duct and a turbofan engine outer shell, the first inner wall face of the additional J duct is in the shape of the inner circumferential wall face of the turbofan engine outer shell, and the second inner wall face of the additional J duct is the outer circumferential wall face of the outer duct; the tip end of the turbofan blade is aligned to the air inlet at the front end of the additional J duct, and is positioned in the area surrounded by the circumferential dimension of the air inlet at the front end of the additional J duct; the air inlet duct openings of the additional J ducts are perpendicular to the air inlet duct openings of the inner ducts and the air inlet duct openings of the outer ducts in space to form three duct air flow structures, and the blade tips of the turbofan blades face the air inlet duct openings of the additional J ducts. Blade rotation resistance is reduced, collision between airflow and the shell is avoided, turbulent flow, turbulent flow and wind cutting harm phenomena are eliminated, airflow fluency is improved, the turbofan air supply amount and efficiency are improved, and the turbofan output power stability is improved.

Description

Technical Field

[0001] The present invention relates to a turbofan engine, and more particularly to an air flow passage of a turbofan engine, for eliminating the turbulence or turbulent flow formed between the tip of the turbofan blade and the inner wall of the housing, and a shock absorption and noise reduction duct structure of the turbofan engine for local crosswind. Background Art

[0002] In existing turbofan engines, the turbulence and turbulent flow between the tip of the turbofan blade and the barrel-shaped housing (casing) is a complex hydrodynamic phenomenon (see Figure 5 ), which mainly involves the following aspects: 1. Tip clearance flow: When the turbofan blade rotates, there is a small clearance between the tip and the housing (casing), resulting in high-pressure air leakage from the pressure side through the tip clearance to the suction side, forming a tip leakage flow 421. This flow is usually unstable and prone to turbulent flow.

[0003] 2. Turbulence generation: The high-speed shear interaction between the leakage flow and the mainstream, the rotation effect of the turbofan blade 50, and the action of the centrifugal force and Coriolis force generated by the blade rotation form a shear layer near the tip, which will generate a vortex flow 422 and turbulent or turbulent flow 423 on the tip surface of the fan blade. The vortex flow and turbulent flow are further broken, thus forming a turbulent zone 423. Turbulence 423 will increase the dissipation of air flow energy and reduce the engine efficiency.

[0004] 3. Vibration and fatigue: The unsteady aerodynamic load caused by turbulent flow may lead to the vibration of the blade and the housing, and long-term action may cause fatigue damage, affecting the engine life.

[0005] 4. Turbulent flow generates resistance: Turbulent flow acts on the blade, not only generating resistance to the blade rotation, but also causing rotational separation or stall phenomena, resulting in blade surging, increasing noise and other problems, especially more obvious for large twist angle turbine blades. If the separation phenomenon caused by turbulent flow occurs in the blade passage of the fan, it will cause blockage of the blade passage, increase the resistance of the blade passage, and at the same time the air pressure will also decrease. As a result, the air delivery volume of the turbofan is reduced, the air delivery efficiency of the turbofan is reduced, the output power of the turbofan fluctuates, and the aerodynamic force received by the turbofan engine becomes unstable, thus affecting the power output.

[0006] In order to counter phenomena such as turbulent flow and turbulent flow and improve the output power of the turbofan engine, engineers usually start from multiple aspects such as optimizing the fan design, optimizing the tip clearance, material innovation, advanced manufacturing processes, and aerodynamic optimization to increase the bypass ratio. Among them, aerodynamic optimization is to perform aerodynamic optimization on parts such as the intake duct and nozzle of the engine, reduce the air flow resistance, and improve the air flow utilization efficiency.

[0007] However, since there must be a gap between the blade tip of the wind turbine and the housing (casing), the generation of turbulent flow is inevitable. Therefore, the defect of turbulent flow phenomenon still exists. Moreover, the above measures are rigid means and a method of forced containment. Implementing these measures will also consume its own power, and it is difficult to eradicate the generation of turbulent flow between the blade tip of the wind turbine and the housing (casing).

[0008] The publicly disclosed patent number ZL 2023112690933 with a publication date of January 2, 2024 discloses a quickly-starting missile turbo-fan engine, including an engine body. The engine body successively forms a core duct and a bypass duct from the inside to the outside. The downstream of the outer wall of the bypass duct is connected to the annular solid rocket engine. The rear nozzle of the annular solid rocket engine is connected to the duct at the front end through an internal pipeline. The other end of the duct forms a nozzle, and the nozzle points to the auxiliary turbine blades of the fan. When the annular solid rocket engine operates and ejects gas backward, a part of the gas enters the duct at the same time; a compressor is provided in the core duct. One end of the compressor is fixedly connected to the turbine, and the other end is equipped with a fan. A combustion chamber is also provided in the core duct. The quickly-starting missile turbo-fan engine described in the present invention can quickly switch from the rocket engine to the thrust output of the turbo-fan engine. However, this solution also has the problems that turbulent flow and chaotic flow are easily formed between the blade tips of the turbo-fan blades and the inner wall of the housing (casing), and even local wind-cutting phenomena will occur, resulting in rotational separation or stall phenomena, causing the blades to surge and increasing the noise, etc. Summary of the Invention

[0009] The present invention provides a shock-absorbing and noise-reducing duct structure for a turbo-fan engine to solve the problems existing in the air flow channel of the existing turbo-fan engine, such as the turbulent flow, chaotic flow and local wind-cutting phenomena formed between the blade tips of the turbo-fan blades and the inner wall of the housing (casing), which lead to resistance to the rotation of the blades, and also cause rotational separation or stall phenomena, resulting in blade surging, increased noise, reduced air delivery volume and air delivery efficiency of the turbo-fan, fluctuating output power of the turbo-fan, unstable aerodynamic force on the turbo-fan engine, and thus affecting power output. The structure can reduce the rotational resistance of the blades, avoid the collision of the air flow with the housing, eliminate the turbulent flow, chaotic flow and the harm of wind-cutting phenomena, increase the smoothness of the air flow, improve the air delivery volume and air delivery efficiency of the turbo-fan, and improve the stability of the turbo-fan output power.

[0010] The specific technical solution adopted by the present invention to solve the above technical problems is as follows: A shock-absorbing and noise-reducing duct structure for a turbofan engine, including a turbofan blade, a turbofan engine outer casing, its inner duct and outer duct. The turbofan blade is arranged inside the intake port of the turbofan engine. It is characterized in that: An additional J duct is additionally arranged between the outer duct and the turbofan engine outer casing. The first inner wall surface of the additional J duct is in the shape of the inner peripheral wall surface of the turbofan engine outer casing, and the second inner wall surface of the additional J duct is the outer peripheral wall surface of the outer duct. The additional J duct has a large circumferential dimension at the front intake port and gradually transitions and becomes smaller from the front intake port to the end outlet; The blade tip of the turbofan blade is aligned with the front intake port of the additional J duct and is within the circumferential dimension surrounding area of the front intake port of the additional J duct, and the blade tip of the turbofan blade extends into the front intake port of the additional J duct; The intake duct opening of the additional J duct is perpendicular to the intake duct opening of the inner duct and the intake duct opening of the outer duct in space, forming three duct airflow structures, and the blade tip of the turbofan blade is arranged towards the intake duct opening of the additional J duct. By adopting the scheme of additionally arranging an additional J duct between the outer duct and the outer casing, a part of the leakage flow that pushes the turbofan (Coriolis force) towards the inner wall of the turbofan engine outer casing is introduced into the additional J duct, avoiding the generation of turbulence and chaotic flow between the blade tip and the inner wall of the casing (cylinder block), so as to eliminate the harm of turbulence, chaotic flow and cutting wind between the blade tip of the turbofan blade and the inner wall of the casing, thereby achieving the purpose of improving the power of the turbofan engine; It can reduce the blade rotation resistance, increase the airflow smoothness, improve the turbofan air supply volume and turbofan air supply efficiency, and improve the stability of the turbofan output power.

[0011] Preferably, a plurality of support plates are distributed in the inner cavity of the additional J duct. The support plates connect and support the first inner wall surface and the second inner wall surface of the additional J duct. The head of each support plate is at the front intake port, and each support plate extends along the inner wall of the additional J duct from the head of the support plate to the end of the additional J duct, dividing the inner cavity of the additional J duct into several additional J duct sub-duct air channels. Improve the stable, reliable and effective support and fixation between the outer duct and the turbofan engine outer casing (that is, the first inner wall surface and the second inner wall surface of the additional J duct). By means of the support plates forming several additional J duct sub-duct air channels, further better maintain and ensure the smooth and stable flow of the air flow in the additional J duct to the rear section of the outer duct.

[0012] Preferably, a plurality of through holes are distributed on the support plates. The plurality of through holes are distributed along the length direction of the support plates from the front end of the head of the support plates to the end of the support plates. The plurality of through holes communicate the adjacent additional J duct sub-duct air channels formed by the support plates. On the basis of the support plates playing the roles of fixing, supporting and connecting the inner walls of the additional J duct, the weight of the support plates is reduced, the airflow connection effect between the adjacent additional J duct sub-duct air channels is improved, and the airflow smoothness and stability in the inner cavity of the additional J duct are improved.

[0013] Preferably, the first inner wall surface of the additional J duct is the inner peripheral wall surface of the outer casing of the turbofan engine with an arc shape arching outward, and the second inner wall surface of the duct of the additional J duct is the outer wall surface of the outer wall of the outer duct, and the outer wall of the outer duct is an outer wall structure with two sections completely separated by sections, or the outer wall of the outer duct is an outer wall structure with separated through holes, and the outer wall structure of the outer duct with separated through holes forms a plurality of outer wall structures with two front and rear separated wall bodies; wherein the outer duct The outer wall of the first section of the outer duct is located at the inlet duct of the additional J duct, and the outer wall of the first section of the outer duct is within the coverage of the arc section of the outer peripheral wall of the turbofan engine casing that arches outward in an arc shape. The outer peripheral wall of the second section of the outer duct is sealed and connected to the end of the inner peripheral wall of the turbofan engine casing. The end outlet of the additional J duct turns from the separation of the outer duct outer wall formed by the first section of the outer duct outer wall and the second section of the outer duct outer wall to merge into the outer duct. While satisfying the purpose of improving the effectiveness of the additional J duct in introducing leakage flow from the tip clearance to the suction surface to form leakage flow, and avoiding the harm caused by turbulent flow; the airflow in the additional J duct can be merged into the outer duct earlier, thereby achieving the effect of improving the airflow efficiency of the outer duct. The inlet duct of the additional J duct is connected with the inner cavity of the additional J duct by an arc transition or an inclined transition, which better avoids the vertical collision of the airflow with the inner wall of the additional J duct to cause swirling flow.

[0014] Preferably, the turbofan engine outer shell has a split outer shell connection structure, forming a split turbofan engine outer shell connection structure composed of a front split outer shell and a rear split outer shell, wherein the front split outer shell is an arc-segment engine outer shell structure, and the circumference of the front air inlet of the additional J duct is within the range covered by the arc-segment engine outer shell of the front split outer shell. After the front split outer shell is disassembled, it is convenient for the disassembly and maintenance of the turbofan blades. Improve the convenience, simplicity and effectiveness of the disassembly and maintenance of the turbofan blades. The arc segment of the additional J duct inlet duct port and the additional J duct inner cavity arc transition or bevel transition connection can better avoid the vertical collision of the airflow with the inner wall of the additional J duct to cause swirl flow.

[0015] Preferably, a valve is provided at the connection between the end of the additional J duct and the rear section of the outer duct, and the valve is opened toward the front of the additional J duct. The degree of opening of the valve decreases with the increase of the airflow thrust of the additional J duct. The airflow of the additional J duct has a reverse push effect on the valve to close the valve, but the airflow thrust of the additional J duct is always insufficient to completely push the valve to close, that is, the valve can be kept in a state of connecting the end of the additional J duct and the rear section of the outer duct under the maximum airflow thrust of the additional J duct. The effectiveness of regulating the airflow flow of the additional J duct connected to the airflow of the outer duct is improved, and the additional J duct is better prevented from becoming a leak channel.

[0016] Preferably, the first inner wall surface of the duct of the additional J-duct is arc-shaped and hooked upwards towards the inner wall of the turbofan engine housing from the air inlet at the front end of the hooked end, and gradually transitions into the outer peripheral side shape structure of the additional J-duct that narrows towards the end air outlet in the direction of the turbofan engine combustion chamber. This improves the effect of the additional J-duct in eliminating the hazards of turbulence, chaotic flow, and crosswind between the tip of the turbofan blade and the inner wall of the housing. The air inlet duct opening of the additional J-duct is connected to the inner cavity of the additional J-duct through an arc transition or an inclined plane transition, which better avoids the formation of swirling flow caused by the perpendicular collision of the air flow with the inner wall surface of the additional J-duct. The air inlet duct opening of the additional J-duct is connected to the inner cavity of the additional J-duct through an arc-shaped hooked and arched transition or an inclined plane transition, which better avoids the formation of swirling flow caused by the perpendicular collision of the air flow with the inner wall surface of the additional J-duct.

[0017] Preferably, the shape of the duct of the additional J-duct is an overall J-shaped duct structure without the horizontal part at the top of the J. The hooked part of the J shape is the front air inlet end of the additional J-duct. The front air inlet of the additional J-duct is connected to the air inlet of the turbofan engine, and the central axis or central plane of the front air inlet of the additional J-duct is perpendicularly arranged in space with the central axis or central plane of the air inlet of the turbofan engine; this forms an additional J-duct with an overall J-duct structure having an arc-shaped hooked body structure, and the hooked end of the arc-shaped hooked body is the circumferential additional J-duct air inlet duct opening inside the front air inlet end of the turbofan engine. This improves the effect of the additional J-duct in eliminating the hazards of turbulence, chaotic flow, and crosswind between the tip of the turbofan blade and the inner wall of the housing.

[0018] Preferably, the additional J-duct communicates with the rear section of the outer duct at its end air outlet and is located in front of the end of the outer wall of the outer duct, forming a siphon air outlet structure. The air flow in the outer duct is used to siphon the air flow in the additional J-duct, increasing the air flow smoothness at the end air outlet of the additional J-duct and combining it with the air flow in the rear section of the outer duct. After eliminating the negative energy of the turbulent and chaotic flow, it is converted into kinetic energy to improve the thrust of the air flow at the outlet of the outer duct. This improves the air flow smoothness at the end air outlet of the additional J-duct and enhances the air flow-driven siphon force.

[0019] Preferably, a deflector is provided for the turbofan blade. The deflector is arranged at the front air inlet of the additional J-duct, and the air flow at the tip of the blade is guided into the front air inlet of the additional J-duct by the deflector. This improves the reliability and effectiveness of guiding the turbulent and chaotic air mass into laminar flow and introducing it into the front air inlet of the J-duct, and avoids the formation of air resistance caused by the turbulent and chaotic air mass in the J-duct.

[0020] Another object of the present invention application is to provide a method for reducing vibration and noise of the turbofan engine duct, which is characterized in that the turbofan engine vibration and noise reduction duct structure described in one of the above technical solutions is adopted, and the following duct vibration and noise reduction measures are implemented: A1. When the turbofan engine is operating, the turbofan blades rotate. While the air flow is pushed into the inlet of the core duct and the inlet of the bypass duct from the air inlet of the turbofan engine housing, due to the gap between the tip of the turbofan blade and the turbofan engine housing, it is introduced into the front inlet of the additional J duct. Therefore, the high-pressure air flow at the tip of the turbofan blade also enters the front inlet of the additional J duct through the guide vane from the tip of the turbofan blade. A2. In the above step A1, there is a tiny tip gap between the tip of the turbofan blade and the front inlet of the additional J duct. The high-pressure air flow leaks from the pressure surface through the tip gap to the front inlet of the additional J duct and forms a leakage flow. It is introduced into the additional J duct before turbulence or chaotic flow is formed, avoiding the harm caused by turbulence or chaotic flow, thereby achieving the purpose of increasing the power of the turbofan engine, making the rotation of the turbofan blades more stable, reducing vibration, and lowering noise. A3. In the above step A1, the guide vane at the front inlet of the additional J duct cuts the turbulent or chaotic flow at the end of the blade, so that this part of the turbulent or chaotic flow at the front inlet of the additional J duct is cut and shredded by the guide vane before being introduced into the additional J duct, achieving the purpose of avoiding the harm caused by turbulence or chaotic flow; after being cut and shredded, it then smoothly enters the additional J duct from the front inlet of the additional J duct, avoiding the collision of this part of the air flow with the inner wall of the turbofan engine housing, eliminating the turbulence or chaotic flow and the harm of cutting wind between the tip of the turbofan blade and the inner wall of the turbofan engine housing, thereby achieving the purpose of increasing the power of the turbofan engine, making the rotation of the turbofan blades more stable, reducing vibration, and lowering noise. A4. In the above steps A1 - A3, during the process of pushing the air flow from the front end to the end outlet of the additional J duct, several support plates arranged in the additional J duct divide the inner cavity of the additional J duct into several additional J duct sub-duct airways. The air flow after the above shock absorption and noise reduction treatment steps is output from each additional J duct sub-duct airway to the end outlet of each additional J duct sub-duct airway, further thoroughly maintaining the smoothness of the air flow in the additional J duct and outputting it to the cavity of the rear section of the bypass duct. A5. In the above steps A1 - A4, the rear section of the bypass duct is connected to the end outlet of the additional J duct to form a siphon port. The air flow in the bypass duct is used to siphon the air flow in the additional J duct, increasing the smoothness of the air flow at the end outlet of the additional J duct, and combining with the air flow in the rear section of the bypass duct to form a thrust. After eliminating the negative energy of the turbulent or chaotic flow, it is converted into kinetic energy to increase the thrust of the air flow at the outlet of the bypass duct. In the above steps A1 - A5, during the process of the air flow being pushed from the front end to the end air outlet of the additional J - duct, the opening degree of the valve arranged at the end air outlet of the additional J - duct decreases as the air flow thrust of the additional J - duct increases. The air flow thrust of the additional J - duct has a reverse pushing effect on the valve to close the valve, but the air flow thrust of the additional J - duct is always not sufficient to completely close the valve, that is, the valve can still maintain the state of connecting the end of the additional J - duct and the rear section of the outer duct under the action of the maximum air flow driving force of the additional J - duct; when the rotational speed of the turbofan blades decreases, the thrust effect of the air flow thrust of the additional J - duct on the valve also decreases, and the opening degree of the valve arranged at the end air outlet of the additional J - duct increases accordingly, achieving the effect of regulating the size of the air flow entering the rear section of the outer duct from the additional J - duct, so that the dynamic air pressure thresholds of the additional J - duct and the outer duct are kept consistent, thereby effectively ensuring the air supply volume and air supply efficiency of the outer duct and the inner duct.

[0021] The beneficial effects of the present invention are as follows: By adopting the scheme of adding an additional J - duct between the outer duct and the outer casing, a part of the leakage flow pushed by the turbofan (Coriolis force) towards the inner wall of the turbofan engine outer casing is introduced into the additional J - duct, avoiding the generation of turbulence and chaotic flow between the tip of the turbofan blade and the inner wall of the casing (cylinder), so as to eliminate the harm of turbulence, chaotic flow and shear wind between the tip of the turbofan blade and the inner wall of the casing, thereby achieving the purpose of improving the power of the turbofan engine; it can reduce the rotational resistance of the blades, increase the smoothness of the air flow, improve the air supply volume and air supply efficiency of the turbofan, and improve the stability of the turbofan output power. The present invention uses the method of guiding and dredging for turbulence and chaotic flow, not only without consuming its own power, but also converting the negative energy of this part of the turbulence and chaotic flow into kinetic energy, which is beneficial to expanding the bypass ratio of the turbofan engine. The front part of the tip of the turbofan blade extends into the intake port of the additional J - duct to eliminate the adverse effects caused by the gap between the tip of the turbofan blade and the inner wall of the casing (cylinder), leading this gap into the inner cavity of the J - duct, avoiding the high - speed shear action between the leakage flow and the mainstream, and the generation probability of turbulence and chaotic flow is low. The inner cavity space of the additional J - duct is relatively large. Even if turbulence and chaotic flow are generated, they are inside the additional J - duct and will not affect the smooth flow of the main air flow in the inner and outer ducts. The intake duct opening of the additional J - duct is connected to the inner cavity of the J - duct through an arc - shaped section or an inclined surface with an arc - shaped transition, avoiding the generation of swirling flow caused by the perpendicular collision of the air flow with the inner wall surface of the additional J - duct. BRIEF DESCRIPTION OF THE DRAWINGS The following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0023] Figure 1 is a schematic structural diagram of the shock - absorption and noise - reduction duct structure of the turbofan engine of the present invention.

[0024] Figure 2 is a partial structural schematic diagram of a duct sketch of the shock - absorption and noise - reduction duct structure of the turbofan engine of the present invention.

[0025] Figure 3 It is a partial structural schematic diagram of another duct sketch of the duct structure for shock absorption and noise reduction of the turbofan engine of the present invention.

[0026] Figure 4 It is a schematic diagram of the support plate of the duct structure for shock absorption and noise reduction of the turbofan engine of the present invention and the divided duct air passages formed thereby.

[0027] Figure 5 It is a partial structural schematic diagram of a duct sketch in the prior art. Detailed implementation manners

[0028] Example 1: Figure 1 、 Figure 3 In the illustrated embodiment, a duct structure for shock absorption and noise reduction of a turbofan engine includes a turbofan blade 50, a turbofan engine outer casing 40, its inner duct 20 and outer duct 10. The turbofan blade 50 is installed inside the intake port 42 of the turbofan engine. An additional J-duct 30 is added between the outer duct 20 and the turbofan engine outer casing 40. The first inner wall surface 41 of the additional J-duct 30 has the shape of the inner peripheral wall surface of the turbofan engine outer casing, and the second inner wall surface 133 of the additional J-duct is the outer peripheral wall surface of the outer duct. The additional J-duct 30 has a large circumferential dimension at the front intake port 31 and gradually transitions and becomes smaller from the front intake port to the end outlet. The blade tip 51 of the turbofan blade 50 is aligned with the front intake port 31 of the additional J-duct and is within the circumferential dimension surrounding area of the front intake port 31 of the additional J-duct. The blade tip 51 of the turbofan blade 50 extends into the front intake port 31 of the additional J-duct or is at the front intake port of the additional J-duct. The intake duct opening 31 of the additional J-duct is perpendicular to the inner duct intake duct opening 22 and the outer duct intake duct opening 11 in space, forming three duct air flow structures. The blade tip 51 of the turbofan blade 50 is arranged facing the intake duct opening 31 of the additional J-duct. The additional J-duct 30 formed between the outer wall of the outer duct 20 and the turbofan engine outer casing 40 can be fixed by adopting or borrowing various flexible fixing modes in the prior art, including but not limited to fixing by bracket connection, fixing by link connection, fixing by front and rear end connection, etc.

[0029] A plurality of through holes 91 are distributed on the support plate 90. The plurality of through holes 91 extend along the length direction of the support plate 90 from the front end of the head of the support plate to the end of the support plate, and the plurality of through holes 91 communicate with the adjacent additional J-duct divided duct air passages 35 formed by the support plate.

[0030] The first inner wall surface 41 of the duct of the additional J-duct 30 is hooked and arched in an arc shape from the front end of the intake port at the hooking end towards the inner wall of the turbofan engine housing, and gradually transitions into the shape structure of the outer peripheral side surface of the additional J-duct that narrows towards the combustion chamber of the turbofan engine and towards the outlet at the end.

[0031] The additional J-duct is hooked and extended in an arc from the inlet end and connected to the rear section of the outer duct. The inner wall surface of the turbofan engine housing in the rear section of the outer duct is arranged with a parallel small inclination angle with the overall outer duct, that is, the inner wall surface of the turbofan engine housing in the rear section of the outer duct is inclined and narrowed from the inner wall surface of the turbofan engine housing at the outlet end of the additional J-duct to the outlet end of the rear section of the outer duct with a small inclination angle reduction. This improves the siphon fluidity effect of the rear section of the outer duct on the outlet air of the additional J-duct and increases the air flow fluidity at the outlet of the additional J-duct.

[0032] Embodiment 2: Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 In the shown embodiment, a number of support plates 90 are distributed and installed in the inner cavity of the additional J-duct. The support plates 90 connect and support the first inner wall surface 41 and the second inner wall surface 133 of the duct of the additional J-duct 30. The head of each support plate 90 is at the front intake port 31, and each support plate 90 extends along the inner wall of the additional J-duct 90 from the head of the support plate to the end of the additional J-duct, dividing the inner cavity of the additional J-duct into several additional J-duct sub-duct air passages 35 (see Figure 4 ); the others are the same as in Embodiment 1.

[0033] Embodiment 3: Figure 1 、 Figure 2 、 Figure 4In the illustrated embodiment, the first inner wall surface 41 of the duct of the additional J-duct 30 is the inner peripheral wall surface of the turbofan engine housing that is arched outward in an arc shape. The second inner wall surface of the additional J-duct is the outer wall surface of the outer duct. The outer wall of the outer duct 10 is a structure of the outer wall body that is completely segmented into two sections (the separation point 133), or the outer wall of the outer duct is a structure of the outer wall body with a separated through-hole (i.e., the separation point 133), and the outer wall body structure with the separated through-hole forms a structure of the outer wall body with multiple front and rear separated wall bodies; among them, the first outer wall body 131 of the outer duct is located at the air inlet of the additional J-duct 31, and the first outer wall body 131 of the outer duct is within the range covered by the arc section 41A that arches outward of the inner peripheral wall surface of the turbofan engine housing. The outer peripheral wall surface of the second outer wall body 132 of the outer duct is hermetically connected to the end section 42A of the inner peripheral wall surface of the turbofan engine housing. The end outlet of the additional J-duct 30 turns and merges into the outer duct from the separation point 133 of the outer wall of the outer duct formed by the first outer wall body and the second outer wall body of the outer duct (see Figure 2 the arrow flow direction shown). The rest is the same as in Embodiment 1 and Embodiment 2.

[0034] Embodiment 4: Figure 1 、 Figure 3 In the illustrated embodiment, the turbofan engine housing 40 has a split housing connection structure, forming a split turbofan engine housing connection structure assembled and disassembled by a front split housing 41B and a rear housing 42B. Among them, the front split housing 41B is an arc-section engine housing structure, and the circumferential dimension of the front air inlet 31 of the additional J-duct is within the range covered by the arc-section engine housing of the front split housing 41B. After the front split housing 41B is disassembled, it is convenient for the disassembly, assembly and maintenance of the turbofan blades 50. The rest is the same as in Embodiment 1 and Embodiment 2.

[0035] Embodiment 5: Figure 1 、 Figure 2 、 Figure 3 、 Figure 4In the embodiment shown, a valve 32 is installed and connected at the connection point between the end of the additional J duct and the rear section of the outer duct. The valve 32 is opened toward the front of the additional J duct 30. The opening degree of the valve 32 decreases with the increase of the airflow thrust of the additional J duct 30. The airflow of the additional J duct 30 has a reverse push to close the valve, but the airflow thrust of the additional J duct 30 is always insufficient to completely push the valve to close, that is, the valve can be kept in a state of connecting the end of the additional J duct with the rear section of the outer duct under the maximum airflow thrust of the additional J duct; the opening degree of the valve is adjusted according to the airflow pressure (i.e., airflow thrust) in the additional J duct to adjust the airflow, and the opening degree of the valve is adjusted to keep the air pressure of the J duct consistent with that of the outer duct, so as to prevent the J duct from becoming a leaking channel. The reverse closing valve function of the valve 32 can be achieved by using components such as pressure springs or torsion springs, and the maximum airflow thrust is obtained by experiments or tests to match the parameters of the components such as the pressure springs or torsion springs used. The opening of the valve can also be controlled by pneumatic, hydraulic or electric control, or a pressure balance valve can be used instead of the valve to achieve airflow regulation.

[0036] Embodiment 6: Figure 1 , Figure 2 , Figure 3 , Figure 4 In the illustrated embodiment, the duct shape of the additional J-duct 30 is a J-shaped duct structure as a whole, but without a J-shaped top cross body, the J-shaped hook portion is the front air inlet end of the additional J-duct, the front air inlet of the additional J-duct is connected to the air inlet of the turbofan engine, and the central axis or central axis plane of the front air inlet 31 of the additional J-duct is spatially perpendicular to the central axis or central axis plane of the air inlet of the turbofan engine; the additional J-duct is formed as a whole to be a J-duct structure with an arc-shaped hook body structure, and the hook end of the arc-shaped hook body is the additional J-duct air inlet duct opening circumferentially inside the front air inlet end of the turbofan engine. In addition, the "J" of the additional J duct is also the pinyin initials of "Ji". From the perspective of military and sports competition rankings, Ji ranks third, which means the third duct; at the same time, "J" is also the pinyin initials of "jia", which can be understood as adding a duct on the basis of the inner and outer ducts of the turbofan engine. Therefore, the above duct shape and the two names are combined into one, referred to as "J duct", and thus defined as the additional J duct 30. The rest is the same as that of Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, and Embodiment 5.

[0037] Embodiment 7: Figure 1 , Figure 2 , Figure 3 , Figure 4In the illustrated embodiment, the additional J-duct 30 communicates with the rear section 12 of the outer duct at its end air outlet, and is located in front of the end of the outer wall of the outer duct, forming a siphon air outlet structure 33. The airflow in the outer duct is used to siphon the airflow in the additional J-duct 30, increasing the airflow smoothness at the end air outlet of the additional J-duct, and merging with the airflow in the rear section of the outer duct. After eliminating the negative energy of the turbulent airflow, it is converted into kinetic energy to improve the thrust of the airflow at the outer duct outlet. The rest is the same as in Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, Embodiment 5, Embodiment 6.

[0038] Embodiment 8: Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 In the illustrated embodiment, a deflector 60 is provided for the fan blades. The deflector 60 is installed at the front end air inlet 31 of the additional J-duct, and the airflow at the blade tip 51 is guided into the front end air inlet 31 of the additional J-duct by the deflector 60. The rest is the same as in Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, Embodiment 5, Embodiment 6, Embodiment 7.

[0039] Embodiment 9: Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 In the illustrated embodiment, a method for reducing vibration and noise of a turbofan engine duct adopts the turbofan engine duct structure for reducing vibration and noise described in one of the above embodiments, and performs the following duct vibration and noise reduction measures: A1. When the turbofan engine is operating, the fan blades rotate. While the airflow is pushed from the air inlet 42 of the turbofan engine housing to enter the inner duct air inlet and the outer duct air inlet, due to the gap between the blade tip 51 of the fan blades 50 and the turbofan engine housing 40 being introduced into the front end air inlet of the additional J-duct (see the arrow flow direction shown in Figure 2 、 Figure 3 ), thus the high-pressure airflow at the blade tip of the fan blades also enters the front end air inlet of the additional J-duct through the deflector from the blade tip of the fan blades; A2. In the above step A1, due to the small tip gap between the blade tip 51 of the fan blades and the front end air inlet 31 of the additional J-duct, the high-pressure airflow leaks from the pressure surface through the tip gap to form a leakage flow at the front end air inlet of the additional J-duct. Before the formation of turbulent or chaotic flow, the leakage flow has been formed and introduced into the additional J-duct, avoiding the harm caused by turbulent or chaotic flow, thereby achieving the purpose of improving the power of the turbofan engine, making the rotation of the fan blades of the turbofan engine more stable, reducing vibration, and lowering noise; A3. In the above step A1, the deflector at the front air inlet of the additional J duct cuts the turbulent flow or eddy current at the end of the blade, so that this part of the turbulent flow or eddy current at the front air inlet of the additional J duct is cut and shredded by the deflector before being introduced into the additional J duct, so as to avoid the harm caused by the turbulent flow or eddy current; after being cut and shredded, it is smoothly introduced into the additional J duct from the front air inlet of the additional J duct, avoiding the collision of this part of the air flow with the inner wall surface of the fan engine housing, so as to eliminate the turbulent flow or eddy current and the harm of the cutting wind between the tip of the fan blade and the inner wall of the fan engine housing, thereby achieving the purpose of improving the power of the fan engine, making the rotation of the fan blades of the fan engine more stable, reducing vibration and noise; A4. In the above steps A1 to A3, during the process of pushing the air flow from the front end of the additional J duct to the end air outlet of the additional J duct, several support plates arranged in the additional J duct divide the inner cavity of the additional J duct into several additional J duct sub-duct air channels, and the air flow after the above shock absorption and noise reduction treatment steps is output from each additional J duct sub-duct air channel to the output port at the end of each additional J duct sub-duct air channel, further thoroughly maintaining and ensuring the smoothness and fluency of the air flow in the additional J duct output to the cavity of the rear section of the outer duct; A5. In the above steps A1 to A4, the rear section of the outer duct is connected to the end air outlet of the additional J duct to form a siphon port 33, and the air flow in the outer duct is used to siphon the air flow in the additional J duct, increasing the fluency of the air flow at the end air outlet of the additional J duct, and combining with the air flow in the rear section of the outer duct to form a thrust, eliminating the negative energy of the turbulent flow or eddy current and converting it into kinetic energy to improve the thrust of the air flow at the outlet of the outer duct; A6. In the above steps A1 to A5, during the process of pushing the air flow from the front end of the additional J duct to the end air outlet at the front end of the additional J duct, the opening degree of the valve arranged at the end air outlet of the additional J duct decreases as the air flow thrust of the additional J duct increases. The air flow thrust of the additional J duct has a reverse pushing and closing effect on the valve, but the air flow thrust of the additional J duct is always not enough to completely close the valve 32, that is, the valve can still be kept in a state of connecting the end of the additional J duct and the rear section of the outer duct under the maximum air flow driving force of the additional J duct; when the rotational speed of the fan blade decreases, the thrust of the air flow of the additional J duct on the valve also decreases, and the opening degree of the valve arranged at the end air outlet of the additional J duct increases accordingly, achieving the effect of adjusting the size of the air flow of the additional J duct entering the rear section of the outer duct, so that the dynamic air pressure thresholds of the additional J duct and the outer duct are kept consistent. The valve 32 can also use a pneumatic balance valve to adjust the air flow and air pressure of the additional J duct, thereby effectively ensuring the air supply volume and air supply efficiency of the outer duct and the inner duct.

[0040] The others are the same as those in Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, Embodiment 5, Embodiment 6, Embodiment 7, and Embodiment 8.

[0041] In the description of the positional relationship of the present invention, terms indicating orientation or positional relationship such as "inner", "outer", "upper", "lower", "left", "right", etc. are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the embodiments and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention.

[0042] The above content and structural description have described the basic principles, main features and advantages of the product of the present invention, which should be understood by those skilled in the art. What is described in the above examples and specifications only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A vibration and noise reduction duct structure for a turbofan engine, comprising a turbofan blade, a turbofan engine outer shell and an inner duct and an outer duct thereof, wherein the turbofan blade is arranged on the inner side of the turbofan engine air inlet, and is characterized in that: An additional J duct is added between the outer duct and the outer casing of the turbofan engine. The first inner wall surface of the additional J duct is in the shape of the inner peripheral wall surface of the outer casing of the turbofan engine, and the second inner wall surface of the additional J duct is in the outer peripheral wall surface of the outer duct. The additional J duct has a large circumference size of the front air inlet and gradually transitions from the front air inlet to the terminal air outlet; the blade tip of the turbofan blade is aligned with the front air inlet of the additional J duct and is located in the area surrounded by the circumference size of the front air inlet of the additional J duct, and the blade tip of the turbofan blade extends into the front air inlet of the additional J duct or is located at the front air inlet of the additional J duct; the air inlet duct opening of the additional J duct is perpendicular to the air inlet opening of the inner duct and the air inlet duct opening of the outer duct in space, respectively, to form three duct airflow structures, and the blade tip of the turbofan blade is arranged toward the air inlet duct opening of the additional J duct.

2. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: A plurality of support plates are distributed in the inner cavity of the additional J duct, the support plates are connected to support the first inner wall surface and the second inner wall surface of the duct of the additional J duct, the head of each support plate is at the front air inlet, and each support plate extends from the head of the support plate along the inner wall of the additional J duct to the end of the additional J duct, dividing the inner cavity of the additional J duct into a plurality of additional J duct sub-duct air ducts; a plurality of through holes are distributed on the support plates, and the plurality of through holes are arranged on the support plates along the length direction of the support plates extending from the front end of the support plate head to the end of the support plate, and the plurality of through holes connect adjacent additional J duct sub-duct air ducts formed by the support plates.

3. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: The first inner wall surface of the additional J duct is the inner peripheral wall surface of the outer casing of the turbofan engine with an arc shape and arched outward, and the second inner wall surface of the duct of the additional J duct is the outer wall surface of the outer wall of the outer duct. The outer wall of the outer duct is an outer wall structure with two sections completely separated by sections, or the outer wall of the outer duct is an outer wall structure with separated through holes, and the outer wall structure of the outer duct with separated through holes forms a plurality of outer wall structures with two separated walls in front and behind; wherein the outer wall of the outer duct A section of the outer wall of the outer duct is located at the air inlet port of the additional J duct, the first section of the outer wall of the outer duct is within the coverage of the arc section of the inner peripheral wall of the outer casing of the turbofan engine, the outer peripheral wall of the second section of the outer wall of the outer duct is sealed and connected to the end section of the inner peripheral wall of the outer casing of the turbofan engine, and the terminal outlet of the additional J duct turns from the separation of the outer wall of the outer duct formed by the first section of the outer wall of the outer duct and the second section of the outer wall of the outer duct to merge and enter the outer duct.

4. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: The turbofan engine outer casing has a split outer casing connection structure, forming a split turbofan engine outer casing connection structure composed of a front split outer casing and a rear split outer casing, wherein the front split outer casing is an arc-section engine outer casing structure, and the circumferential size of the front air inlet of the additional J duct is within the range covered by the arc-section engine outer casing of the front split outer casing. After the front split outer casing is disassembled, it is convenient for disassembly and maintenance of the turbofan blades.

5. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: A valve is provided at the connection between the end of the additional J duct and the rear section of the outer duct. The valve is opened toward the front of the additional J duct. The degree of opening of the valve decreases with the increase of the airflow thrust of the additional J duct. The airflow of the additional J duct has a reverse pushing effect on the valve to close the valve, but the airflow thrust of the additional J duct is always insufficient to completely push the valve to close, that is, the valve can be kept in a state of connecting the end of the additional J duct and the rear section of the outer duct under the action of the maximum airflow thrust of the additional J duct.

6. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: The first inner wall surface of the additional J duct is hooked in an arc shape from the air inlet at the front end of the hook end toward the inner wall of the turbofan engine casing, and gradually transitions into the additional J duct outer peripheral side shape structure that narrows toward the turbofan engine combustion chamber toward the end air outlet.

7. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: The duct shape of the additional J-duct is a J-shaped duct structure as a whole, but without a J-shaped top cross body, the J-shaped hook portion is the front air inlet end of the additional J-duct, the front air inlet of the additional J-duct is connected to the air inlet of the turbofan engine, and the central axis or central axis plane of the front air inlet of the additional J-duct is spatially perpendicular to the central axis or central axis plane of the air inlet of the turbofan engine; the additional J-duct is formed as a whole to be a J-duct structure with an arc-shaped hook body structure, and the hook end of the arc-shaped hook body is the additional J-duct air inlet duct opening circumferentially inside the front air inlet end of the turbofan engine.

8. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: The additional J duct is connected to the rear section of the outer duct at its terminal air outlet and is located in front of the terminal end of the outer wall of the outer duct, forming a siphon outlet structure. The outer duct airflow is used to siphon the airflow in the J duct, thereby increasing the airflow smoothness at the terminal air outlet of the additional J duct and merging the two with the airflow at the rear section of the outer duct, thereby eliminating the negative energy of the turbulent flow and converting it into kinetic energy to increase the thrust of the airflow at the outer duct outlet.

9. The vibration and noise reduction duct structure of a turbofan engine according to claim 1, characterized in that: A guide plate is provided for the turbofan blade, and the guide plate is arranged at the front air inlet of the additional J duct. The guide plate is used to guide the airflow at the tip of the blade into the front air inlet of the additional J duct.

10. A method for reducing vibration and noise of a turbofan engine duct, characterized in that: The turbofan engine vibration reduction and noise reduction duct structure according to any one of claims 1 to 9 is adopted to implement the following duct vibration reduction and noise reduction measures: A1. When the turbofan engine is working, the turbofan blades rotate, and the airflow pushes the air from the air inlet of the turbofan engine outer shell into the inner duct air inlet duct and the outer duct air inlet duct. At the same time, due to the gap between the tip of the turbofan blade and the turbofan engine outer shell, the airflow is introduced into the front air inlet of the additional J duct. Therefore, the high-pressure airflow at the tip of the turbofan blade is also introduced from the tip of the turbofan blade into the front air inlet of the additional J duct through the guide plate; A2. In the above step A1, there is a tiny gap between the tip of the turbofan blade and the front air inlet of the additional J duct. When the high-pressure airflow leaks from the pressure surface through the tip gap to the front air inlet of the additional J duct, a leakage flow is formed. The leakage flow is introduced into the additional J duct before turbulence or turbulence is formed, thereby avoiding the harm caused by turbulence or turbulence, thereby achieving the purpose of improving the power of the turbofan engine, making the fan blades of the turbofan engine rotate more smoothly, reducing vibration and noise; A3. In the above step A1, the guide plate at the front air inlet of the additional J duct cuts off the turbulent flow or turbulence at the end of the blade, so that this part of the turbulent flow or turbulence at the front air inlet of the additional J duct is cut and shredded by the guide plate before being introduced into the additional J duct, thereby avoiding the harm caused by the turbulent flow or turbulence; after cutting and shredding, it is smoothly introduced from the front air inlet of the additional J duct and then enters the additional J duct, thereby avoiding the collision of this part of the airflow with the inner wall of the turbofan engine casing, thereby eliminating the turbulent flow or turbulence between the tip of the turbofan fan blade and the inner wall of the turbofan engine casing and the harm of cutting wind, thereby achieving the purpose of improving the power of the turbofan engine, making the fan blades of the turbofan engine rotate more smoothly, reducing vibration and reducing noise; A4. In the above steps A1 to A3, when the airflow is pushed from the front end of the additional J duct to the air outlet at the end of the additional J duct, a plurality of support plates arranged in the additional J duct divide the inner cavity of the additional J duct into a plurality of additional J duct sub-duct air ducts, and the airflow after the above vibration reduction and noise reduction processing steps is output from each additional J duct sub-duct air duct to the output port at the end of each additional J duct sub-duct air duct, so as to further better maintain and ensure the smoothness and flow of the airflow in the additional J duct to the rear section of the outer duct; A5. In the above steps A1 to A4, the rear section of the outer duct is connected to the terminal air outlet of the additional J duct to form a siphon port, and the airflow of the outer duct is used to siphon the airflow in the additional J duct, thereby increasing the smoothness of the airflow at the terminal air outlet of the additional J duct, and combining the airflow with the airflow of the rear section of the outer duct to form a thrust, eliminating the negative energy of turbulence or turbulence and converting it into kinetic energy, thereby increasing the thrust of the airflow at the outlet of the outer duct; A6. In the above steps A1 to A5, in the process of pushing the airflow from the front end of the additional J duct to the air outlet at the end of the additional J duct, the opening degree of the valve arranged at the end air outlet of the additional J duct decreases with the increase of the airflow thrust of the additional J duct. The airflow thrust of the additional J duct has a reverse pushing effect on the valve to close the valve, but the airflow thrust of the additional J duct is always insufficient to completely close the valve, that is, the valve can be kept in a state of connecting the end of the additional J duct with the rear section of the outer duct under the action of the maximum airflow thrust of the additional J duct; when the speed of the turbofan blades decreases, the thrust effect of the airflow thrust of the additional J duct on the valve is also reduced, and the opening degree of the valve arranged at the end air outlet of the additional J duct increases accordingly, so as to adjust the airflow size of the airflow of the additional J duct entering the rear section of the outer duct, so that the dynamic air pressure thresholds of the additional J duct and the outer duct remain consistent, thereby effectively ensuring the air supply volume and air supply efficiency of the outer duct and the inner duct.

Images