Variable-area rear duct ejector of controllable airflow alternating structure for variable-cycle engine

Abstract

The invention discloses a variable-area rear duct ejector of a controllable airflow alternating structure for a variable-cycle engine, and relates to a variable-cycle engine. Comprising a rectangular alternating mixer, a large-area and small-area adjusting valve body, a central cone, a driving device and a gear transmission mechanism. In the single outer culvert mode, the small-area adjusting valve body corresponds to the long valve leaflet, and the large-area adjusting valve body blocks the short valve leaflet flow channel, so that the outer culvert airflow is mixed with the inner culvert airflow through the long valve leaflet. In the double-outer-culvert mode, the adjusting valve body coincides with the upper rectangular valve leaflet, and outer-culvert airflow is not affected. The long valve leaflet is high in penetration rate, and outer culvert cold air flow is conveyed to an inner culvert core to promote mixing. The large and small area adjusting valve body inclines in the outer duct and has the same inclination angle with the upper rectangular valve leaflet, one end is arranged in a slide way to facilitate movement, the other end is connected with a rack and is driven by a driving device and a gear transmission mechanism to move and adjust the circulation area, and the rotation range is 0-12 degrees. The airflow generates a flow direction vortex after passing through the rectangular alternating mixer, mixing is promoted, a uniform flow field is obtained, and the combustion efficiency and the engine performance are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of variable cycle engine structure design, and in particular relates to a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine. Background Art

[0002] As the power unit of the next generation of fighter jets, the variable cycle engine combines the low fuel consumption of a large bypass ratio turbofan engine under subsonic flight conditions and the high thrust of a turbojet engine under supersonic conditions. It adjusts the engine's thermal cycle parameters by changing the geometry, size or position of some adjustable components of the engine, so that the engine has suitable thermal cycle parameters under various operating conditions, greatly improving the aircraft performance.

[0003] The rear variable area duct ejector is one of the important adjustable components of the variable cycle engine to change the thermal cycle parameters. It is similar to a variable area mixer. It changes the area ratio of the inner and outer ducts of the engine, thereby adjusting the flow rate of the inner and outer ducts, and matches with the mode selection valve and the front duct ejector to achieve the purpose of adjusting the thermal cycle parameters of the variable cycle engine.

[0004] The gas in the outer duct is mixed with the inner and outer duct airflow after passing through the rear duct ejector. The mixing effect will greatly affect the combustion efficiency of the afterburner and thus affect the thrust performance of the engine. In the traditional translational and rotational area adjustment scheme, the mixing between the inner and outer duct airflows only relies on the shearing effect of one airflow contact surface, and the mixing effect is poor. The introduction of the alternating mixer greatly improves the mixing efficiency of the inner and outer duct airflows, and the rectangular flap processing is more convenient.

[0005] In recent years, research on variable area rear duct ejectors has been carried out both at home and abroad, but most of the adjustment schemes only consider completing area adjustment and do not achieve high thermal mixing efficiency; therefore, proposing a rear duct ejector that can effectively adjust the area while achieving high thermal mixing efficiency and low total pressure loss has become a hot spot and difficulty in current research. Summary of the invention

[0006] The purpose of the present invention is to address the above-mentioned technical problems existing in the prior art and to provide a variable-area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine. The invention aims to achieve efficient mixing and flexible adjustment of the inner and outer duct airflows by introducing a rectangular alternating mixer and a large and small area regulating valve body matching it, and by precisely controlling the movement of the area regulating valve body of the rear duct ejector and the rectangular alternating mixer, thereby meeting the performance requirements of the variable cycle engine in different modes and reducing the total pressure loss.

[0007] To achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows.

[0008] A variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, comprising: a rectangular alternating mixer, a large and small area regulating valve body, a central cone, a driving device, and a gear transmission mechanism;

[0009] A rectangular alternating mixer, comprising a plurality of rectangular lobes, wherein the rectangular lobes are divided into short rectangular lobes of a rectangular alternating mixer and long rectangular lobes of a rectangular alternating mixer, and the lobes are arranged around a central cone and extend to an inner duct and an outer duct;

[0010] The large and small area regulating valve bodies include a large area regulating valve body and a small area regulating valve body, which are used to adjust the area of ​​the rear duct ejector. The large area regulating valve body and the small area regulating valve body are connected to the driving device through a gear transmission mechanism and can be rotated and moved as needed;

[0011] The central cone is located at the center of the entrance of the endogenous channel;

[0012] A driving device, used for providing power to drive the gear transmission mechanism and the area regulating valve body;

[0013] A gear transmission mechanism, used to transmit the power of the driving device to the area regulating valve body to realize its rotation and movement;

[0014] The design parameters include the inclination angle of the area regulating valve body of the rear duct ejector to the horizontal direction, the inner and outer duct inclination angles of the rectangular flaps of the rectangular alternating mixer, and the number, width, shape and geometric distribution of the large and small area regulating valve bodies;

[0015] In single outer duct mode, the large and small area regulating valve bodies are evenly distributed at the outer duct outlet of the variable cycle engine according to the distribution law of the large area regulating valve body corresponding to the inner rectangular short petal and the small area regulating valve body corresponding to the inner rectangular long petal, and the long and short petal settings of the rectangular alternating mixer are set; when the variable cycle engine is in double outer duct mode, the area regulating valve body overlaps with the rectangular petal on the rectangular alternating mixer, and does not affect the circulation of the outer duct airflow; the rotation angle of the area regulating valve body is 0~12°, and the rotation drive device drives the gear mechanism to rotate, thereby driving the rotation of the area regulating valve body to realize area regulation.

[0016] The rectangular alternating mixer is equipped with a total of 36 rectangular leaflets, 18 of which are located in the outer duct and the other 18 are located in the inner duct. The leaflets in the outer duct are evenly distributed, and their angles with the horizontal plane are designed to be 5° to 20° according to actual needs. The rectangular leaflets in the inner duct are alternately and evenly distributed by 9 long rectangular leaflets of the rectangular alternating mixer and 9 short rectangular leaflets of the rectangular alternating mixer. The angles of the short rectangular leaflets of the rectangular alternating mixer with the horizontal plane are designed to be 5° to 25°, and the angles of the long rectangular leaflets of the rectangular alternating mixer with the horizontal plane are 10° to 40°. The inclination angle of the long rectangular leaflets of the rectangular alternating mixer is always greater than the inclination angle of the short rectangular leaflets of the rectangular alternating mixer, and the angle difference between the two does not exceed 20°.

[0017] The lower end of the area regulating valve body is fixed in the semicircular slideway located on the inner wall of the outer duct, and the upper end is clamped in the circumferential movable slideway reserved on the outer wall of the outer duct, and its exposed part is designed as a circumferential rack shape, which is tightly meshed with the gear transmission mechanism. The inclination angle and number of the area regulating valve body and the horizontal plane are consistent with the rectangular petals of the outer duct. The inclination angle and number of the area regulating valve body and the horizontal plane are the same as the inclination angle of the rectangular petals located in the outer duct and the horizontal plane. The outer duct airflow flows into the gap between adjacent rectangular petals to reduce pressure loss.

[0018] The driving device has the function of forward and reverse rotation, and can drive the gear mechanism to rotate clockwise or counterclockwise, and then drive the valve body to rotate through the circumferential rack structure at the upper end of the area adjustment valve body. The final position of the valve body in space is determined according to the working state of the variable cycle engine and the required minimum bypass ratio.

[0019] The rotation angle range of the area regulating valve body is set to 0° to 12°. The driving device drives the gear transmission mechanism to rotate, thereby driving the rotation of the area regulating valve body to achieve effective regulation of the flow area.

[0020] The windward surfaces of the large-area regulating valve body and the small-area regulating valve body are set to a triangular structure to optimize the airflow guiding effect and reduce flow loss. The circumferential angle occupied by each rectangular leaflet is determined according to the total number of leaflets and remains consistent to ensure uniform distribution of airflow.

[0021] When the variable cycle engine is in single outer saccade mode, the position of the small-area regulating valve body corresponds to the long flap of the alternating mixer, and the large-area regulating valve body corresponds to the short flap. The large-area regulating valve body blocks the flow passage of the short flap, thereby allowing the outer saccade airflow to flow through the long flap into the inner saccade and mix with the inner saccade airflow. When the variable cycle engine is in double outer saccade mode, the large and small-area regulating valve bodies overlap with the upper rectangular flap, which does not affect the circulation of the outer saccade airflow. The long vanes of the rectangular alternating mixer have a high penetration rate in the flow field of the inner duct, and can transport the cold airflow of the outer duct to the core of the inner duct to better promote the mixing of the inner and outer duct airflows. The large and small area valve bodies are placed in the outer duct, and their inclination angle in the outer duct is consistent with the inclination angle of the upper rectangular vanes of the rectangular alternating mixer. One end of the area valve body is placed on the inner wall of the outer duct and is provided in a slideway for easy movement, and the other end is connected to the rack clamped on the outer wall of the outer duct. According to the modal change requirements of the variable cycle engine, the self-rotating actuator is started, and then the rack outside the outer wall of the outer duct is driven to move through the gear transmission mechanism, thereby driving the movement of the area regulating valve body to achieve the purpose of adjusting the flow area of ​​the outer duct. The rotation range of the large and small area regulating valve bodies is 0~12°. After the inner and outer duct airflows flow through the rectangular alternating mixer, the flow vortex generated further promotes the mixing of the inner and outer duct airflows, obtains a uniform flow field, improves the combustion efficiency of the afterburner, and thus improves the engine performance.

[0022] The present invention has the following beneficial effects:

[0023] In a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, a rectangular alternating mixer is introduced. In the dual outer duct mode, the large and small area regulating valve bodies basically overlap with the upper rectangular flaps located in the outer duct, and the outer duct airflow flows into the long and short rectangular flaps of the rectangular alternating mixer, which effectively reduces the pressure loss. The windward surfaces of the large and small area regulating valve bodies are set to a triangular structure to be able to guide the flow well. At this time, the area regulating mechanism will not bring any extra pressure loss to the flow field, and has very high thermal mixing efficiency and low pressure loss. When the mode of the variable cycle engine changes from the dual outer duct mode to the single outer duct mode, the drive device starts to rotate and drive the gear mechanism to rotate, and then drives the rack of the area regulating valve to rotate, thereby driving the rotation of the large and small area regulating valve bodies, blocking the flow channel corresponding to the short rectangular flap, so that the outer duct airflow can only flow into the inner duct from the long rectangular flap. The long rectangular vanes of the alternating mixer have a higher penetration rate in the inner duct, and can send the airflow of the outer duct to the core of the inner airflow, better promoting the mixing of the inner and outer duct airflows. In addition, when the inner and outer duct airflows flow through the rectangular alternating mixer, a flow vortex structure will be generated. And because the strength and range of the flow vortices generated by the long and short rectangular vanes are inconsistent, the adjacent flow vortex systems will interact with each other to promote the mixing of the inner and outer duct airflows in a larger range, creating excellent inlet conditions for the afterburner, thereby improving the overall performance of the variable cycle engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the overall assembly diagram of the variable area rear duct ejector with controllable airflow alternating structure.

[0025] Figure 2 It is a schematic diagram of the external duct airflow flow in the double external duct mode of the variable area rear duct ejector with controllable airflow alternating structure.

[0026] Figure 3 It is a schematic diagram of the external duct airflow flow in a single external duct mode of a variable area rear duct ejector with a controllable airflow alternating structure.

[0027] Figure 4 It is a schematic diagram of the structure of the large and small area regulating valve body.

[0028] Figure 5 Schematic diagram of the rectangular alternating mixer structure.

[0029] Figure 6 It is a structural diagram of the gear transmission mechanism.

[0030] Figure 7 The diagram is a schematic diagram of the connection structure of the two ends of the area regulating valve body. Among them, a-upper end clamping fixed structure diagram, b-lower end clamping fixed structure diagram.

[0031] The marks in the figure are: 1-external duct inlet, 2-internal duct inlet, 3-center cone, 4-short rectangular flaps of rectangular alternating mixer, 5-long rectangular flaps of rectangular alternating mixer, 6-gear transmission mechanism, 7-driving device, 8-large area regulating valve body, 9-small area regulating valve body, 10-rack. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following embodiments will further illustrate the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims.

[0033] Combination Figures 1 to 7 An embodiment of the present invention provides a variable-area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine. The outer duct inlet 1 is annular and is used to introduce airflow from the external environment. The inner duct inlet 2 is located inside the outer duct inlet 1 to guide the airflow from the inside of the engine into the ejector. The central cone 3 is located at the center of the inner duct inlet 2 to reduce the resistance of the airflow when passing through.

[0034] The variable area rear duct ejector with controllable airflow alternating structure for variable cycle engine of the present invention comprises a rectangular alternating mixer, a large area regulating valve body 8, a small area regulating valve body 9, a central cone 3, a driving device 7, and a gear transmission mechanism 6;

[0035] The rectangular alternating mixer is composed of a plurality of rectangular lobes, including short rectangular lobes 4 and long rectangular lobes 5 of the rectangular alternating mixer; the short rectangular lobes 4 and long rectangular lobes 5 of the rectangular alternating mixer are arranged around the central cone 3 and extend to the inner duct and the outer duct. Through precise arrangement and angle design, the short rectangular lobes 4 and long rectangular lobes 5 of the rectangular alternating mixer can effectively guide and mix the airflow from the outer duct and the inner duct.

[0036] In this embodiment, the rectangular alternating mixer is equipped with 36 rectangular lobes, 18 of which are located in the outer duct and the other 18 are located in the inner duct. The lobes of the outer duct are evenly distributed, and the angle with the horizontal plane is designed to be 5 to 20° according to actual needs. The rectangular lobes of the inner duct are evenly distributed alternately by 9 long rectangular lobes 5 of the rectangular alternating mixer and 9 short rectangular lobes 4 of the rectangular alternating mixer. The angle of the short rectangular lobes 4 of the rectangular alternating mixer and the horizontal plane is designed to be 5 to 25°, and the angle of the long rectangular lobes 5 of the rectangular alternating mixer and the horizontal plane is 10 to 40°, and the inclination angle of the long rectangular lobes 5 of the rectangular alternating mixer is always greater than the inclination angle of the short rectangular lobes 4 of the rectangular alternating mixer, and the angle difference between the two does not exceed 20°. The circumferential angle occupied by each lobe is determined according to the total number of lobe leaves and remains consistent. For example, in this embodiment, the circumferential angle occupied by each lobe is 10°.

[0037] When the variable cycle engine switches to the dual duct mode, the large area regulating valve body 8 and the small area regulating valve body 9 are located exactly on the back of the rectangular flap on the duct, that is, the large area regulating valve body 8 and the small area regulating valve body 9 are moved to overlap with the upper rectangular flap (that is, the extension of the long rectangular flap 5 of the rectangular alternating mixer or the short rectangular flap 4 of the rectangular alternating mixer in the duct part), ensuring that the duct airflow is not hindered from flowing through the lower rectangular flaps. The rotation angle range of the area regulating valve body is set to 0-12°, and the gear transmission mechanism 6 is driven by the driving device 7 to rotate, thereby driving the rotation of the area regulating valve body to achieve effective adjustment of the flow area.

[0038] When the engine switches to the single outer duct mode, the area regulating valve body begins to move circumferentially, gradually reducing the flow area between the lower rectangular flaps, until the flow channel corresponding to the short rectangular flap 4 of the rectangular alternating mixer is completely closed by the large area regulating valve body 8, that is, the large area regulating valve body 8 corresponds to and covers the flow channel of the short rectangular flap 4 of the inner rectangular alternating mixer, and the small area regulating valve body 9 corresponds to and covers the peripheral area of ​​the long rectangular flap 5 of the inner rectangular alternating mixer, and the two are evenly distributed at the outer duct outlet of the variable cycle engine according to the setting of the long and short flaps of the rectangular alternating mixer. The outer duct airflow is forced to be redirected from the long rectangular flap 5 of the rectangular alternating mixer into the core area of ​​the inner duct airflow, thereby realizing the precise adjustment of the outer duct area.

[0039] The lower end of the area regulating valve body is fixed in a semicircular slideway located on the inner wall of the outer duct, and the upper end is clamped in a circumferential movable slideway reserved on the outer wall of the outer duct, and its exposed part is designed as a circumferential rack, and the rack 10 is tightly meshed with the gear transmission mechanism 6. The inclination angle and number of the area regulating valve body with the horizontal plane are consistent with the rectangular leaflets of the outer duct, aiming to reduce the pressure loss when the outer duct airflow flows through the gap between adjacent rectangular leaflets.

[0040] The driving device 7 has the function of forward and reverse rotation, and can drive the gear mechanism to rotate clockwise or counterclockwise, and then drive the valve body to rotate through the circumferential rack structure at the upper end of the area adjustment valve body. The final position of the valve body is determined according to the working state of the variable cycle engine and the required minimum bypass ratio.

[0041] The large-area regulating valve body 8 and the small-area regulating valve body 9 are used to adjust the area of ​​the rear duct ejector. The large-area regulating valve body 8 and the small-area regulating valve body 9 are connected to the driving device 7 through the gear transmission mechanism 6 and can be rotated and moved as needed.

[0042] The core variable area function of the ejector of the present invention is realized by the rectangular alternating mixer and the large and small area regulating valve bodies. When the engine operates in the single outer duct mode, the small area regulating valve body 9 precisely corresponds to the position of the long rectangular flap 5 of the rectangular alternating mixer, and the large area regulating valve body 8 accurately covers the short rectangular flap 4 of the rectangular alternating mixer, and physically blocks the flow path of the short rectangular flap 4 of the rectangular alternating mixer, forcing the outer duct airflow to be completely redirected to flow through the long rectangular flap 5 of the rectangular alternating mixer, and then fully mixed with the inner duct of the inner duct. When the engine switches to the dual outer duct mode, the large area regulating valve body 8 and the small area regulating valve body 9 do not interfere with any flap of the rectangular alternating mixer, ensuring that the outer duct airflow can flow freely.

[0043] The design of the rectangular alternating mixer is particularly ingenious. The long rectangular leaflets 5 of the rectangular alternating mixer can effectively guide the cold airflow of the outer duct to the core area of ​​the inner duct airflow due to its high flow field penetration rate, greatly promoting the mixing efficiency of the inner and outer duct airflows. The large-area regulating valve body 8 and the small-area regulating valve body 9 are cleverly installed in the outer duct. Their inclination angles perfectly match the inclination angles of the long rectangular leaflets 5 of the rectangular alternating mixer to ensure a smooth transition of the airflow. One end of the two valve bodies can be flexibly moved through the slideway on the inner wall of the outer duct, and the other end is firmly connected to the rack on the outer wall of the outer duct.

[0044] According to the engine's mode conversion requirements, the drive device 7 is started in time, and the movement of the rack on the outer wall of the outer duct is accurately controlled through the gear transmission mechanism 6, thereby driving the large-area regulating valve body 8 and the small-area regulating valve body 9 to rotate or translate within the range of 0 to 12 degrees to achieve fine adjustment of the flow area of ​​the outer duct. This design not only optimizes the mixing effect of the airflow, but also significantly improves the combustion efficiency of the afterburner, thereby comprehensively enhancing the overall performance of the engine.

[0045] The working principle of the present invention is given below:

[0046] Initial state: When the engine is started and in the dual duct mode, the large-area regulating valve body 8 and the small-area regulating valve body 9 are both in the initial position and do not interfere with any flap of the rectangular alternating mixer. At this time, the airflow of the duct can smoothly pass through the flap gap of the rectangular alternating mixer, while the airflow of the inner duct is preliminarily mixed with the airflow of the duct through the guidance of the central cone 3.

[0047] Mode conversion: When the engine needs to be converted from the dual-outer duct mode to the single-outer duct mode, the drive device 7 starts to work, and drives the large-area regulating valve body 8 and the small-area regulating valve body 9 to rotate and move through the gear transmission mechanism 6. The large-area regulating valve body 8 will move to the position corresponding to the short rectangular flap 4 of the inner duct rectangular alternating mixer, and completely close it, thereby preventing the airflow of the corresponding flow channel of the short rectangular flap 4 of the rectangular alternating mixer from passing through. At the same time, the small-area regulating valve body 9 will also move to the position corresponding to the long rectangular flap 5 of the inner duct rectangular alternating mixer and the flap of the outer duct, and change the area and airflow direction of the flow channel corresponding to these flaps by adjusting their rotation angle and position.

[0048] Airflow mixing and regulation: In the single outer duct mode, through the precise regulation of the large-area regulating valve body 8 and the small-area regulating valve body 9, the airflow in the outer duct is guided to the corresponding flow channel of the rectangular alternating mixer long rectangular leaflet 5 of the inner duct, and is efficiently mixed with the airflow from the inner duct. At the same time, due to the sealing effect of the large-area regulating valve body 8 on the short rectangular leaflet 4 of the rectangular alternating mixer, unnecessary airflow loss and interference are avoided.

[0049] During the whole process, the engine control system can adjust and optimize the drive device 7 and the gear transmission mechanism 6 according to the real-time monitored airflow parameters and engine performance data to ensure that the airflow management of the rear duct ejector reaches the optimal state.

[0050] The present invention successfully realizes a variable-area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine. The ejector achieves efficient management and optimization of the airflow of the engine in different modes by precisely controlling the movement of the large-area regulating valve body 8 and the small-area regulating valve body 9 and the arrangement and angle design of the rectangular alternating mixer.

[0051] Figure 1 The figure is an overall assembly diagram of a variable area rear duct ejector with controllable internal and external duct airflow according to an embodiment of the present invention, which mainly illustrates the spatial position of the internal and external ducts and the driving mechanism of the variable area duct ejector. Figure 2 This is a schematic diagram of the distribution of the area adjustment large and small valve bodies of the variable area rear duct ejector with a controllable airflow alternating structure in the dual outer duct mode. In the variable cycle engine dual outer duct mode, the area of ​​the outer duct is at its largest state. At this time, the position of the large and small area adjustment valve bodies along the circumferential distribution basically coincides with the upper rectangular leaflets located in the outer duct. The airflow in the outer duct flows along the gaps between the rectangular leaflets located in the outer duct, that is, along the long and short rectangular leaflets located in the inner duct, gradually to the core of the inner airflow, and better mixes with the inner airflow. When the mode of the variable cycle engine changes, the gear structure is driven to rotate by the rotation of the drive device, which in turn drives the rack at the upper end of the area adjustment valve body to rotate, thereby realizing the rotation of the valve body, such as Figure 3 Schematic diagram of the distribution of the area regulating valve body of the variable-area rear duct ejector in the near-transition mode for efficient mixing of the inner and outer duct airflows. The rotation of the large and small area regulating valve bodies blocks the flow channel corresponding to the short rectangular leaflet, so that the outer duct airflow can only flow into the inner duct from the long rectangular leaflet.

[0052] Figure 4 The valve body is an area regulating valve body. The driving device drives the valve body to rotate in the circumferential direction to achieve the change of its spatial position, and cooperates with the rectangular alternating mixer to change the flow area of ​​the outer duct. Figure 5It is a rectangular alternating mixer. When the airflow flows through the rectangular alternating mixer, a flow vortex structure will be generated. Because the strength and range of the flow vortices generated by the long and short rectangular blades are inconsistent, the interaction between the long and short adjacent flow vortices will promote the mixing of the inner and outer airflows in a larger range, making the inner and outer airflows mixed more evenly to a greater extent, greatly reducing the mixing distance, and solving the problem of the difficulty of mixing the inner and outer airflows caused by the increase in the outer flow rate in the near-turbofan mode, further improving the conditions at the inlet of the afterburner, improving the efficiency of the afterburner, and thus improving the performance of the entire variable cycle engine. The design of the rectangular alternating mixer can make the flow vortices generated by the long and short rectangular blades different in strength and range. This difference promotes the interaction between adjacent flow vortices, thereby promoting the mixing of the inner and outer airflows in a larger range.

[0053] Compared with the existing rear duct ejector area adjustment scheme, the present invention adopts a rectangular alternating mixer and sets a large and small area adjustment valve body that matches it. Most of the cold airflow in the outer duct flows through the rectangular leaflets located in the outer duct. In the single outer duct mode, the large area adjustment valve body corresponds to the short leaflet, and the small area adjustment valve body corresponds to the long leaflet. Most of the outer duct airflow flows into the inner duct through the long leaflet. In the double outer duct mode, the position of the large and small area adjustment valve body coincides with the upper rectangular leaflet, which does not affect the flow of the outer duct airflow, and the windward surface of the large and small area adjustment valve body is set to a triangular structure, which can effectively reduce the flow loss caused by the large and small area valve body to the outer duct airflow, and guide the airflow into the lower rectangular leaflet and then into the inner duct. The flow area between the upper rectangular leaflets of the outer duct is controlled by circumferential rotation to control the flow of the outer duct. The outer duct airflow flows through the area adjustment valve body and then flows through the rectangular alternating mixer. The large and small area adjustment valve body can ensure that the outer duct airflow passes through the long rectangular leaflet to enter the inner duct and mix with the inner duct airflow in the single outer duct mode of the single outer duct. Due to the presence of long rectangular leaflets, the alternating mixer has a higher penetration rate in the inner duct than general moment mixers and wave lobe mixers. It can deliver the cold flow of the outer duct to the hot flow of the inner duct, thereby greatly improving the mixing efficiency of the inner and outer ducts. In addition, the alternating mixer will have interaction between the flow vortices induced by the long and short rectangular leaflets in the double outer duct mode and transition mode, which can promote the mixing of the inner and outer duct airflows in a larger range.

[0054] The above embodiments are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: include: Rectangular alternating mixer, area regulating valve body, center cone, drive device, gear transmission mechanism; A rectangular alternating mixer, comprising a plurality of rectangular lobes, wherein the rectangular lobes are divided into short rectangular lobes of a rectangular alternating mixer and long rectangular lobes of a rectangular alternating mixer, and the lobes are arranged around a central cone and extend to an inner duct and an outer duct; The area regulating valve body includes a large area regulating valve body and a small area regulating valve body, which are used to adjust the area of ​​the rear duct ejector. The large area regulating valve body and the small area regulating valve body are connected to the driving device through a gear transmission mechanism and can be rotated and moved as needed; The central cone is located at the center of the entrance of the endorheic channel; A driving device, used for providing power to drive the gear transmission mechanism and the area regulating valve body; A gear transmission mechanism, used to transmit the power of the driving device to the area regulating valve body to realize its rotation and movement; The design parameters include the inclination angle of the area regulating valve body of the rear duct ejector to the horizontal direction, the inclination angle of the inner and outer ducts of the rectangular flaps of the rectangular alternating mixer, and the number, width, shape and geometric distribution of the area regulating valve body; In single outer duct mode, the area regulating valve body is evenly distributed at the outer duct outlet of the variable cycle engine according to the distribution law of the internal rectangular short leaflets corresponding to the large area regulating valve body and the internal rectangular long leaflets corresponding to the small area regulating valve body, and the long and short leaflets of the rectangular alternating mixer are set; when the variable cycle engine is in double outer duct mode, the area regulating valve body coincides with the rectangular leaflets on the rectangular alternating mixer and does not affect the circulation of the outer duct airflow; the rotation angle of the area regulating valve body is 0~12°, and the rotation drive device drives the gear mechanism to rotate, thereby driving the rotation of the area regulating valve body to realize area regulation.

2. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: The rectangular alternating mixer is equipped with 36 rectangular leaflets, 18 of which are located in the outer duct and the other 18 in the inner duct. The leaflets in the outer duct are evenly distributed, and their angle with the horizontal plane is designed to be 5° to 20° according to actual needs. The rectangular leaflets in the inner duct are alternately and evenly distributed by 9 long rectangular leaflets of the rectangular alternating mixer and 9 short rectangular leaflets of the rectangular alternating mixer. The angle of the short rectangular leaflets of the rectangular alternating mixer with the horizontal plane is designed to be 5° to 25°, and the angle of the long rectangular leaflets of the rectangular alternating mixer with the horizontal plane is 10° to 40°. The inclination angle of the long rectangular leaflets of the rectangular alternating mixer is always greater than the inclination angle of the short rectangular leaflets of the rectangular alternating mixer, and the angle difference between the two does not exceed 20°.

3. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: The lower end of the area regulating valve body is fixed in the semicircular slide located on the inner wall of the outer duct, and the upper end is clamped in the circumferential movable slide reserved on the outer wall of the outer duct, and its exposed part is designed to be a circumferential rack shape, which is tightly engaged with the gear transmission mechanism. The inclination angle and number of the area regulating valve body and the horizontal plane are consistent with the rectangular leaflets of the outer duct; the inclination angle and number of the area regulating valve body and the horizontal plane are the same as the inclination angle of the rectangular leaflets located in the outer duct and the horizontal, and the outer duct airflow flows into the gap between adjacent rectangular leaflets to reduce pressure loss.

4. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: The driving device has the function of forward and reverse rotation, which can drive the gear mechanism to rotate clockwise or counterclockwise, and then drive the valve body to rotate through the circumferential rack structure at the upper end of the area adjustment valve body. The final position of the valve body in space is determined according to the working state of the variable cycle engine and the required minimum bypass ratio.

5. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: The rotation angle range of the area regulating valve body is set to 0° to 12°. The driving device drives the gear transmission mechanism to rotate, thereby driving the rotation of the area regulating valve body to achieve effective regulation of the flow area.

6. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: When the variable cycle engine is in the dual-circuit mode, the area of ​​the duct is at its largest state, and the large-area regulating valve body and the small-area regulating valve body overlap with the upper rectangular flaps located in the duct, ensuring that the flow of the duct airflow through the lower rectangular flaps is not hindered. At this time, the area regulating mechanism will not cause any unnecessary pressure loss to the flow field; when the variable cycle engine switches to the single-circuit mode, the area regulating valve body begins to move circumferentially, gradually reducing the flow area between the lower rectangular flaps until the flow channel corresponding to the short rectangular flaps of the rectangular alternating mixer is completely closed by the large-area regulating valve body, forcing the duct airflow to be completely redirected from the long rectangular flaps of the rectangular alternating mixer into the core area of ​​the internal airflow, thereby realizing precise adjustment of the duct area.

7. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: The windward surfaces of the large-area regulating valve body and the small-area regulating valve body are set to a triangular structure to optimize the airflow guiding effect and reduce flow losses.

8. According to claim 1, a variable area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine, characterized in that: The circumferential angle occupied by each rectangular leaflet is determined based on the total number of leaflets and remains consistent to ensure uniform distribution of airflow.

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