A turbofan engine duct airflow distribution mechanism and control method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AECC SICHUAN GAS TURBINE RES INST
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-02
Smart Images
Figure CN122129361A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of overall structural design of aero-engines, and discloses an aero-engine ducted airflow distribution mechanism and its control method. Background Technology
[0002] Aero engines are classified into various types, including turbofan engines, turbojet engines, and turboshaft engines. Compared to turbojet engines, turbofan engines have an additional bypass duct, allowing them to drive more air to generate thrust, which helps reduce fuel consumption. However, because turbofan engines do not significantly heat the airflow through the bypass duct, the difference between the exhaust velocity and the ambient atmospheric velocity decreases as flight speed increases, leading to a rapid drop in thrust. Therefore, the maximum speed of a turbofan engine is often lower than that of a turbojet engine, and the higher the bypass ratio, the lower the maximum speed. To address this contradiction, variable flow path engines, which operate in turbofan mode with an bypass duct at low speeds and in turbojet mode with the bypass duct shut off at high speeds, can combine the advantages of low fuel consumption at low speeds (like turbofan engines) and high thrust at high speeds (like turbojet engines), representing a promising future direction in aero-engine development.
[0003] Figure 1 A schematic diagram of a variable flow path engine mechanism is shown. Figure 1 The components include: fan 1, supercharger 2, high-pressure compressor 3, combustion chamber 4, high-pressure turbine 5, low-pressure turbine 6, bypass duct 7, mixer 8, tail nozzle 9, high-pressure shaft, and low-pressure shaft. Figure 1 The upper and middle sections operate in turbofan mode, where the engine behaves like a conventional turbofan engine. The lower section operates in turbojet mode, where the bypass duct is closed and the airflow is redirected into the internal duct. Simultaneously, the flow path components are adjusted to reduce the compressor flow rate and pressure ratio, making the overall engine operation resemble that of a turbojet engine. Figure 1 The middle arrow indicates the direction of airflow. However, existing variable flow path engines still have many problems to be solved in terms of duct airflow distribution and regulation. For example, most common duct flow path regulation schemes currently use an external drive mechanism to rotate a flap to cut off the outer duct. This type of drive structure requires additional engine nacelle space, which increases the overall weight of the engine and offsets the performance gains brought by the variable flow path design. At the same time, the external mechanism works in the high temperature and high pressure environment of the engine nacelle for a long time, which is prone to failures such as sealing failure and jamming of moving parts, and the reliability is difficult to meet the requirements of long-term flight. Summary of the Invention
[0004] The purpose of this invention is to provide an airflow distribution mechanism and control method for an aero-engine duct, which can support the requirements of variable flow path aero-engines to operate in turbofan engine mode at low flight speeds and turbojet mode at high flight speeds, thus broadening the flight speed range of conventional turbofan engines and achieving a balance between high economy at low speeds and high thrust at high speeds.
[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:
[0006] An airflow distribution mechanism for an aircraft engine duct, comprising: The first support plate is disposed inside the engine's outer bypass duct. The first support plate is formed by combining a split first front edge and a first rear edge. The first front edge is radially fixed between the split casing and the outer ring casing that form the outer bypass duct. The first rear edge is a groove-shaped structure with an open front end and a closed rear end. The second support plate is disposed in the engine inner cavity corresponding to the axial position of the first support plate. The second support plate is formed by combining a split second front edge and a second rear edge. The second front edge is fixed radially between the inner ring casing and the split casing that form the inner cavity. The second rear edge is a groove-shaped structure with an open front end and a closed rear end. A rotating casing is coaxially mounted on the diverter casing, and the first trailing edge and the second trailing edge are fixed on the rotating casing. The first trailing edge and the second trailing edge are used to drive the first trailing edge and the second trailing edge to rotate synchronously, so as to adjust the flow area of the outer duct flow channel at the first support plate position and the inner duct flow channel at the second support plate position. The first air vent is disposed on the rotating casing corresponding to the first trailing edge groove structure; The second air vent is disposed in the flow divider casing and is used to maintain a misalignment with the first air vent when both the outer bypass channel at the first support plate position and the inner bypass channel at the second support plate position are in the open state, and to radially coincide with the first air vent when both the outer bypass channel at the first support plate position and the inner bypass channel at the second support plate position are in the closed state, so as to connect the inner cavity of the first trailing edge groove structure with the inner bypass channel.
[0007] Furthermore, when the rotating casing rotates the first trailing edge to the corresponding first leading edge axial position, the first trailing edge and the corresponding first leading edge combine to form a complete stator blade, and the second trailing edge and the corresponding second leading edge combine to form a complete stator blade.
[0008] Furthermore, when the rotating casing rotates the first trailing edge to a downstream position between two adjacent first leading edges, the two upstream end faces of the first trailing edge contact and seal with the corresponding two tail end faces of the first leading edge, and the two upstream end faces of the second trailing edge contact and seal with the corresponding two tail end faces of the second leading edge.
[0009] Furthermore, both the first leading edge and the second leading edge have a streamlined shape, and the flow area blockage ratio of the first leading edge and the second leading edge is greater than or equal to 50%.
[0010] Furthermore, the radial height distribution function at each axial position on the deflection wall curve of the first trailing edge is: ,in Indicates the axial position on the deflection wall curve of the first trailing edge. radial height at that location , The effective axial transition length of the internal guiding cavity of the first trailing edge groove structure. The radial height of the deflection wall curve at the inlet is the first trailing edge. The radial height of the deflection wall curve at the first trailing edge at the outlet.
[0011] Furthermore, the radial height distribution function at each axial position on the deflection wall curve of the second trailing edge is: ,in Indicates the axial position on the deflection wall curve of the second trailing edge. radial height at that location , The effective axial transition length of the internal guiding cavity of the second trailing edge groove structure. The radial height of the deflection wall curve at the inlet is the second trailing edge. The radial height of the deflection wall curve at the outlet is the second trailing edge.
[0012] To achieve the above technical effects, the present invention also provides a control method for an aero-engine ducted airflow distribution mechanism, the method being based on the aforementioned aero-engine ducted airflow distribution mechanism, comprising: According to the operating conditions or working mode of the aero-engine, the rotating casing is adjusted to synchronously drive the first trailing edge and the second trailing edge to rotate around the engine axis, so as to synchronously adjust the flow area of the outer bypass duct at the first support plate position and the inner bypass duct at the second support plate position.
[0013] Furthermore, the aero-engine includes a fan, compressor, combustion chamber, turbine, outer bypass duct, inner bypass duct, and nozzle; When the aero-engine is in turbofan operating mode, the rotating casing is controlled to axially align the first trailing edge and the first leading edge of the first support plate to form a complete guide stator blade in the outer bypass duct; and the second trailing edge and the second leading edge of the second support plate are axially aligned to form a complete guide stator blade in the inner bypass duct. After the aero-engine reaches a preset Mach number, the drive rotating casing rotates the first trailing edge to a downstream position between two adjacent first leading edges, so that the two upstream end faces of the first trailing edge contact and seal with the two tail end faces of the corresponding first leading edge, and the two upstream end faces of the second trailing edge contact and seal with the two tail end faces of the corresponding second leading edge, jointly blocking the axial flow section of the outer bypass duct corresponding to the first support plate and the axial flow section of the inner duct corresponding to the second support plate, and making the first air bleed hole and the second air bleed hole connect the inner cavity of the first trailing edge groove structure with the inner duct, guiding the air in the outer bypass duct to the engine inner duct, so that the aero-engine is in turbojet working mode.
[0014] Compared with the prior art, the beneficial effects of this invention are: this invention can support the requirement of variable flow path aero engines to operate in turbofan engine mode at low flight speeds and turbojet mode at high flight speeds, effectively expanding the flight speed range of conventional turbofan engines and achieving a balance between high economy at low speeds and high thrust at high speeds; moreover, the entire switching process only requires driving the rotating casing to rotate a small angle, and the flow path can be quickly switched without large-stroke axial movement, resulting in a more compact overall structure and effectively reducing the overall weight and structural complexity of the engine. Attached Figure Description
[0015] Figure 1 A schematic diagram of a variable flow path starting mechanism; Figure 2 This is a schematic diagram of the airflow distribution mechanism of the aero-engine duct in the embodiment; Figure 3 This is a schematic diagram of the turbofan mode with the inner and outer bypass ducts fully open in the embodiment. Figure 4 This is a schematic diagram illustrating the engagement of the first leading edge and the first trailing edge in the embodiment; Figure 5 This is a schematic diagram showing the inner and outer bypass ducts of the turbojet mode in the embodiment being closed. Figure 6 This is a schematic diagram of the engine flow channel cross-section when the inner and outer bypass ducts are closed in the turbojet mode of the embodiment; Among them, 1. Fan; 2. Supercharger compressor; 3. High-pressure compressor; 4. Combustion chamber; 5. High-pressure turbine; 6. Low-pressure turbine; 7. Outer bypass duct; 8. Mixer; 9. Tail nozzle; 10. First leading edge; 11. First trailing edge; 12. Streamer casing; 13. Outer ring casing; 14. Channel structure; 15. Inner duct; 16. Second leading edge; 17. Second trailing edge; 18. Inner ring casing; 19. Rotating casing; 20. First bleed port; 21. Second bleed port. Detailed Implementation
[0016] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.
[0017] Example See Figures 1 to 6 An airflow distribution mechanism for an aircraft engine duct, comprising: The first support plate is disposed in the outer bypass duct 7 of the engine. The first support plate is formed by combining a split first front edge 10 and a first rear edge 11. The first front edge 10 is radially fixed between the flow divider casing 12 and the outer ring casing 13 that form the outer bypass duct 7. The first rear edge 11 is a groove-shaped structure 14 with an open front end and a closed rear end. The second support plate is disposed in the engine inner channel 15 corresponding to the axial position of the first support plate. The second support plate is formed by combining a split second front edge 16 and a second rear edge 17. The second front edge 16 is fixed radially between the inner ring casing 18 and the split casing 12 that form the inner channel 15. The second rear edge 17 is a groove-shaped structure 14 with an open front end and a closed rear end. The rotating casing 19 is coaxially sleeved on the diverting casing 12, and the first trailing edge 11 and the second trailing edge 17 are fixed on the rotating casing 19. The rotating casing 19 is used to drive the first trailing edge 11 and the second trailing edge 17 to rotate synchronously, so as to adjust the flow area of the outer duct 7 at the first support plate position and the inner duct 15 at the second support plate position. The first air vent 20 is disposed on the rotating casing 19 corresponding to the groove structure 14 of the first rear edge 11; The second air vent 21 is disposed in the flow divider casing 12. It is used to maintain a misalignment with the first air vent 20 when the outer duct 7 at the first support plate position and the inner duct 15 at the second support plate position are both in the open state, and to radially coincide with the first air vent 20 when the outer duct 7 at the first support plate position and the inner duct 15 at the second support plate position are both in the closed state, so as to connect the inner cavity of the groove structure 14 of the first trailing edge 11 with the inner duct 15.
[0018] In this embodiment, by integrating the air intake structure and flow path control structure into the support plate structure of the rotating casing 19 and the inner and outer bypass ducts 7, the first trailing edge 11 of the first support plate in the outer bypass duct 7, the second trailing edge 17 of the second support plate in the inner bypass duct 15, and the circumferential rotation of the rotating casing 19 enable the leading and trailing edges of the corresponding support plates of the outer bypass duct 7 and the inner bypass duct 15 to match in turbofan mode, resulting in smooth flow in the inner and outer bypass ducts 7. In turbojet mode, the first trailing edge 11 of the first support plate in the outer bypass duct 7 is driven by the actuator of the rotating casing 19 to move along the... The first support plate rotates circumferentially by half an angle between the first support plates, thus misaligning with the first leading edge 10 of the first support plate and blocking the flow section of the outer bypass duct 7. Simultaneously, the second trailing edge 17 of the second support plate within the inner bypass duct 15, driven by the actuator of the rotating casing 19, rotates circumferentially by half an angle between the second support plates, thus misaligning with the second leading edge 16 of the second support plate and blocking the flow section of the inner bypass duct 15. This exposes the air vent at the location of the hollow slot structure 14 of the first support plate of the outer bypass duct 7, guiding the airflow originally blocked by the outer bypass duct 7 into the inner bypass duct 15. This invention supports the requirement for variable flow path aero-engines to operate in turbofan mode at low flight speeds and turbojet mode at high flight speeds, broadening the flight speed range of conventional turbofan engines and achieving a balance between high economy at low speeds and high thrust at high speeds. Compared to traditional structures that adjust the opening of the ducted air intake, the first air intake vent 20 in this embodiment always rotates synchronously with the rotating casing 19. It only aligns and connects with the hollow slot of the first trailing edge 11 when the turbojet mode needs to be activated. This eliminates the need for an additional independent opening and closing valve to control the air intake passage, further reducing unnecessary moving parts, lowering the probability of mechanism failure, and improving the reliability of the entire ducted air intake adjustment mechanism. This makes it more suitable for stable operation under long-term high-speed flight conditions. Moreover, the entire switching process only requires rotating the rotating casing 19 by a small angle, achieving rapid flow path switching without large-stroke axial movement. The overall structure is more compact, effectively reducing the overall weight and structural complexity of the engine.
[0019] It should be noted that the splitter casing 12 divides the engine flow channel into an inner bypass duct 15 and an outer bypass duct 7, and has the function of constraining the airflow in the inner and outer bypass ducts 7. It can also cooperate with the rotating casing 19 to perform axial positioning and fix the shaft center.
[0020] In this embodiment, both the first leading edge 10 and the second leading edge 16 have streamlined shapes, and the flow area blockage ratio of the first leading edge 10 and the second leading edge 16 is greater than or equal to 50%. When the rotating casing 19 rotates the first trailing edge 11 to the corresponding axial position of the first leading edge 10, the first trailing edge 11 and the corresponding first leading edge 10 combine to form a complete stator blade, and the second trailing edge 17 and the corresponding second leading edge 16 combine to form a complete stator blade.
[0021] In this embodiment, when the rotating casing 19 rotates the first trailing edge 11 to a downstream position between two adjacent first leading edges 10, the two upstream end faces of the first trailing edge 11 contact and seal with the corresponding two tail end faces of the first leading edge 10, and the two upstream end faces of the second trailing edge 17 contact and seal with the corresponding two tail end faces of the second leading edge 16. This ensures the sealing effect of the outer bypass duct 7. When the rotating casing 19 rotates in the opposite direction by half the included angle between the first support plates and returns to the initial position, the upstream end face of the first trailing edge 11 will completely fit with the downstream end face of the first leading edge 10 of the adjacent first support plate, and the second trailing edge 17 will similarly completely fit with the second leading edge 16 of the second support plate. At this time, the flow channel walls of the entire outer bypass duct 7 and inner bypass duct 15 are complete and smooth streamlined curved surfaces. When the airflow flows along the streamlined wall surface, almost no additional boundary layer separation loss is generated. This ensures the aerodynamic efficiency of the independent flow of the inner and outer bypass ducts 7 in turbofan mode, and does not increase the overall wind resistance of the engine due to the additional flow passage structure, thus adapting to the fuel economy requirements at low flight speeds.
[0022] When the engine is in turbojet mode, the airflow needs to cross radially from the outer bypass duct 7 through the internal cavity of the first support plate to the inner bypass duct 15. If a conventional straight-line chamfered (Z-shaped) flow path is used, the airflow will encounter extremely strong centrifugal force abrupt changes and adverse pressure gradients at sharp turns, leading to boundary layer separation, the generation of large-area vortex zones (dead water zones), and consequently, a significant reduction in effective flow area and total fluid pressure loss. Therefore, in this embodiment, a quintic polynomial is used to construct an S-shaped flow path. At this time, the radial height distribution function at each axial position on the deflection wall curve of the first trailing edge 11 is: ,in Indicates the axial position on the deflection wall curve of the first trailing edge 11. radial height at that location , The effective axial transition length of the internal guiding cavity of the first trailing edge 11 groove structure 14 is given by [the relevant data point]. The radial height of the deflection wall curve at the inlet of the first trailing edge 11 is given by [reference to a specific feature]. The radial height of the deflection wall curve of the first trailing edge 11 at the outlet. This higher-order function can strictly ensure that the flow direction of the airflow at the inlet (outer bypass 7 side) and outlet (inner bypass 15 side) is completely parallel to the engine axis (first derivative is 0), and that the wall curvature is absolutely continuous (second derivative is 0), thus ensuring smooth airflow.
[0023] Similarly, in this embodiment, the radial height distribution function at each axial position on the deflection wall curve of the second trailing edge 17 is: ,in Indicates the axial position on the deflection wall curve of the second trailing edge 17. radial height at that location , The effective axial transition length of the internal guiding cavity of the second trailing edge 17 groove structure 14. The radial height of the deflection wall curve of the second trailing edge 17 at the inlet. The radial height of the deflection wall curve of the second trailing edge 17 at the outlet.
[0024] It should be noted that the relevant polynomial coefficients in the deflection wall curve of the first trailing edge 11 and the deflection wall curve of the second trailing edge 17 are the same. Sharing this set of coefficients ensures that the two ends of the curve are tangent to the wall (first derivative is 0) and the curvature is continuous (second derivative is 0), resulting in a smooth transition of the curve. The actual steepness and length of the curve are adjusted by the radial height difference and axial length values in the formula (equivalent to stretching and scaling).
[0025] Based on the same inventive concept, this embodiment also provides a control method for an aero-engine ducted airflow distribution mechanism, the method being based on the aforementioned aero-engine ducted airflow distribution mechanism, comprising: According to the operating conditions or working mode of the aero-engine, the rotating casing 19 is adjusted to synchronously drive the first trailing edge 11 and the second trailing edge 17 to rotate around the engine axis, so as to synchronously adjust the flow area of the outer bypass duct 7 at the first support plate position and the inner bypass duct 15 at the second support plate position.
[0026] As described in this embodiment, the aircraft engine includes a fan 1, a booster compressor 2, a high-pressure compressor 3, a combustion chamber 4, a high-pressure turbine 5, a low-pressure turbine 6, an outer bypass duct 7, a mixer 8, and a tail nozzle 9. When the aero-engine is in turbofan operating mode, the rotating casing 19 is controlled to axially align the first trailing edge 11 and the first leading edge 10 of the first support plate, forming a complete guide stator blade inside the outer bypass duct 7; and axially align the second trailing edge 17 and the second leading edge 16 of the second support plate, forming a complete guide stator blade inside the inner bypass duct 15; at this time, the first air vent 20 and the second air vent 21 are misaligned, and the airflow in the outer bypass duct 7 cannot pass through, making the airflow in the inner and outer bypass ducts 7 independent of each other; After the aero-engine reaches a preset Mach number, the drive rotating casing 19 rotates the first trailing edge 11 to a downstream position between two adjacent first leading edges 10, so that the two upstream end faces of the first trailing edge 11 contact and seal with the two tail end faces of the corresponding first leading edge 10, and the two upstream end faces of the second trailing edge 17 contact and seal with the two tail end faces of the corresponding second leading edge 16, jointly blocking the axial flow section of the outer bypass duct 7 corresponding to the first support plate and the axial flow section of the inner duct 15 corresponding to the second support plate, and making the first air bleed hole 20 and the second air bleed hole 21 connect the inner cavity of the groove structure 14 of the first trailing edge 11 with the inner duct 15, guiding the air in the outer bypass duct 7 to the engine inner duct 15, realizing the distribution of the flow from the outer bypass duct 7 to the inner duct 15, so that the aero-engine is in turbojet working mode.
[0027] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A bypass airflow distribution mechanism for an aircraft engine, characterized in that, include: The first support plate is disposed inside the engine's outer bypass duct. The first support plate is formed by combining a split first front edge and a first rear edge. The first front edge is radially fixed between the split casing and the outer ring casing that form the outer bypass duct. The first rear edge is a groove-shaped structure with an open front end and a closed rear end. The second support plate is disposed in the engine inner cavity corresponding to the axial position of the first support plate. The second support plate is formed by combining a split second front edge and a second rear edge. The second front edge is fixed radially between the inner ring casing and the split casing that form the inner cavity. The second rear edge is a groove-shaped structure with an open front end and a closed rear end. A rotating casing is coaxially mounted on the diverter casing, and the first trailing edge and the second trailing edge are fixed on the rotating casing. The first trailing edge and the second trailing edge are used to drive the first trailing edge and the second trailing edge to rotate synchronously, so as to adjust the flow area of the outer duct flow channel at the first support plate position and the inner duct flow channel at the second support plate position. The first air vent is disposed on the rotating casing corresponding to the first trailing edge groove structure; The second air vent is disposed in the flow divider casing and is used to maintain a misalignment with the first air vent when both the outer bypass channel at the first support plate position and the inner bypass channel at the second support plate position are in the open state, and to radially coincide with the first air vent when both the outer bypass channel at the first support plate position and the inner bypass channel at the second support plate position are in the closed state, so as to connect the inner cavity of the first trailing edge groove structure with the inner bypass channel.
2. The airflow distribution mechanism for an aero-engine duct according to claim 1, characterized in that, When the rotating casing rotates the first trailing edge to the corresponding first leading edge axial position, the first trailing edge and the corresponding first leading edge combine to form a complete stator blade, and the second trailing edge and the corresponding second leading edge combine to form a complete stator blade.
3. The airflow distribution mechanism for an aero-engine duct according to claim 2, characterized in that, When the rotating casing rotates the first trailing edge to a downstream position between two adjacent first leading edges, the two upstream end faces of the first trailing edge contact and seal with the two tail end faces of the corresponding first leading edge, and the two upstream end faces of the second trailing edge contact and seal with the two tail end faces of the corresponding second leading edge.
4. The airflow distribution mechanism for an aero-engine duct according to claim 1, characterized in that, Both the first leading edge and the second leading edge have a streamlined shape, and the flow area blockage ratio of the first leading edge and the second leading edge is greater than or equal to 50%.
5. The airflow distribution mechanism for an aero-engine duct according to claim 1, characterized in that, The radial height distribution function at each axial position on the deflection wall curve of the first trailing edge is: ,in Indicates the axial position on the deflection wall curve of the first trailing edge. radial height at that location , The effective axial transition length of the internal guiding cavity of the first trailing edge groove structure. The radial height of the deflection wall curve at the inlet is the first trailing edge. The radial height of the deflection wall curve at the first trailing edge at the outlet.
6. The airflow distribution mechanism for an aero-engine duct according to claim 1, characterized in that, The radial height distribution function at each axial position on the deflection wall curve of the second trailing edge is: ,in Indicates the axial position on the deflection wall curve of the second trailing edge. radial height at that location , The effective axial transition length of the internal guiding cavity of the second trailing edge groove structure. The radial height of the deflection wall curve at the inlet is the second trailing edge. The radial height of the deflection wall curve at the outlet is the second trailing edge.
7. A control method for an aero-engine ducted airflow distribution mechanism, the method being based on the aero-engine ducted airflow distribution mechanism according to any one of claims 1-6, characterized in that, include: According to the operating conditions or working mode of the aero-engine, the rotating casing is adjusted to synchronously drive the first trailing edge and the second trailing edge to rotate around the engine axis, so as to synchronously adjust the flow area of the outer bypass duct at the first support plate position and the inner bypass duct at the second support plate position.
8. The control method for the airflow distribution mechanism of an aero-engine duct according to claim 7, characterized in that, The aero-engine includes a fan, compressor, combustion chamber, turbine, outer bypass duct, inner bypass duct, and nozzle; When the aero-engine is in turbofan operating mode, the rotating casing is controlled to axially align the first trailing edge and the first leading edge of the first support plate to form a complete guide stator blade in the outer bypass duct; and the second trailing edge and the second leading edge of the second support plate are axially aligned to form a complete guide stator blade in the inner bypass duct. After the aero-engine reaches a preset Mach number, the drive rotating casing rotates the first trailing edge to a downstream position between two adjacent first leading edges, so that the two upstream end faces of the first trailing edge contact and seal with the two tail end faces of the corresponding first leading edge, and the two upstream end faces of the second trailing edge contact and seal with the two tail end faces of the corresponding second leading edge, jointly blocking the axial flow section of the outer bypass duct corresponding to the first support plate and the axial flow section of the inner duct corresponding to the second support plate, and making the first air bleed hole and the second air bleed hole connect the inner cavity of the first trailing edge groove structure with the inner duct, guiding the air in the outer bypass duct to the engine inner duct, so that the aero-engine is in turbojet working mode.