A variable area rear duct ejector with controllable airflow alternating structure for a variable cycle engine

Abstract

A variable-area rear duct ejector with a controllable alternating airflow structure for a variable-cycle engine relates to a variable-cycle engine. It comprises a rectangular alternating mixer, a large-area and small-area regulating valve body, a central cone, a drive unit, and a gear transmission mechanism. In single-outer duct mode, the small-area regulating valve body corresponds to the long lobes, while the large-area regulating valve body blocks the short-lobed flow path, allowing the outflow flow to mix entirely with the inner flow through the long lobes. In dual-outer duct mode, the regulating valve body overlaps with the upper rectangular lobes, without affecting the outflow flow. The long lobes have high penetration, transporting the cold outflow flow to the inner core to promote mixing. The large-area regulating valve body is tilted in the outflow duct, matching the inclination angle of the upper rectangular lobes. One end is equipped with a slide for easy movement, and the other end is connected to a rack. Driven by a drive unit and gear transmission mechanism, it adjusts the flow area, with a rotation range of 0 to 12 degrees. After passing through the rectangular alternating mixer, the airflow generates a directional vortex, promoting mixing and achieving a uniform flow field, improving combustion efficiency and engine performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of variable cycle engine structure design, and specifically 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 thermodynamic cycle parameters by changing the geometry, size or position of some adjustable components of the engine, so that the engine has suitable thermodynamic cycle parameters under various operating conditions, greatly improving aircraft performance.

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

[0004] After passing through the rear duct ejector, the gas in the outer duct is mixed with the inner and outer duct flows. The effect of this mixing significantly affects the combustion efficiency of the afterburner and, consequently, the engine's thrust performance. Traditional translational and rotational area adjustment schemes rely solely on the shearing effect of a single airflow contact surface, resulting in poor mixing. However, the proposed alternating mixer significantly improves the mixing efficiency of the inner and outer duct flows, and its rectangular vanes are more easily manufactured.

[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 topic 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 the rectangular alternating mixer and long rectangular lobes of the rectangular alternating mixer, and the lobes are arranged around the central cone and extend to the inner duct and the 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 endorheic tract;

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

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

[0014] Design parameters include the inclination angle of the area-adjusting valve body of the rear duct ejector relative to the horizontal direction, the inner and outer duct inclination angles of the rectangular leaflets of the rectangular alternating mixer, and the number, width, shape and geometric distribution of the large and small area-adjusting 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 rules of the large area regulating valve body corresponding to the inner rectangular short leaflet and the small area regulating valve body corresponding to the inner rectangular long leaflet, 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 leaflet 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 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 leaflet of the rectangular alternating mixer is always greater than the inclination angle of the short rectangular leaflet 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 a semicircular slideway on the inner wall of the duct, while the upper end is engaged in a circumferentially movable slideway reserved on the outer wall of the duct. Its exposed portion is designed as a circumferential rack, tightly meshing with the gear transmission mechanism. The inclination angle and number of the area-regulating valve body with the horizontal plane are consistent with those of the rectangular lobes in the duct. The inclination angle and number of the area-regulating valve body with the horizontal plane are the same as those of the rectangular lobes in the duct. The duct airflow flows into the gap between adjacent rectangular lobes, reducing pressure loss.

[0018] 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-adjusting 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 rotation of the gear transmission mechanism, thereby driving the rotation of the area regulating valve body to achieve effective adjustment of the flow area.

[0020] The windward surfaces of the large and small control valve bodies are triangular in shape to optimize airflow guidance and minimize flow losses. The circumferential angle occupied by each rectangular leaflet is determined by the total number of leaflets and remains consistent to ensure even airflow distribution.

[0021] When the variable cycle engine is in single-bypass mode, the small-area regulating valve body corresponds to the long flap of the alternating mixer, while the large-area regulating valve body corresponds to the short flap. The large-area regulating valve body blocks the flow path of the short flap, allowing the entire bypass airflow to flow through the long flap into the bypass and mix with the bypass airflow. When the variable cycle engine is in dual-bypass mode, the large and small-area regulating valve bodies overlap with the upper rectangular flap, without affecting the flow of the bypass 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 airflow, thereby better promoting 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 vane of the rectangular alternating mixer. One end of the area valve body is placed on the inner wall of the outer duct and a slide is set in it 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 adjustment valve body to achieve the purpose of adjusting the flow area of ​​the outer duct. The rotation range of the large and small area adjustment 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 flap located in the outer duct, and the outer duct airflow flows into the long and short rectangular flaps of the rectangular alternating mixer, effectively reducing the pressure loss. The windward surfaces of the large and small area regulating valve bodies are both set to a triangular structure to enable good drainage. At this time, the area regulating mechanism will not bring any unnecessary 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 drives the gear mechanism to rotate, which in turn 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 high penetration rate in the inner duct, which 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 intensity and range of the flow vortices generated by the long and short rectangular vanes are inconsistent, the interaction between adjacent flow vortex systems will 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 ducted ejector with a controllable airflow alternating structure.

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

[0026] Figure 3 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 This is a schematic diagram of the connection structure of the two ends of the area control valve body. Among them, a-the upper end clamping and fixing structure diagram, b-the lower end clamping and fixing structure diagram.

[0031] The marks in the figure are: 1-external duct inlet, 2-endoduct inlet, 3-center cone, 4-short rectangular lobes of rectangular alternating mixer, 5-long rectangular lobes 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 clear, the following embodiments will be combined with the accompanying drawings to further illustrate the present invention. 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 solution made on the essence and scope of the present invention as defined by the claims.

[0033] Combine 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 and guides 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 and is used to reduce the resistance of the airflow when passing through.

[0034] The variable-area rear duct ejector with a controllable airflow alternating structure for a variable cycle engine according to 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. These lobes are arranged around a central cone 3 and extend into the inner and outer ducts. Through precise arrangement and angle design, the short rectangular lobes 4 and the long rectangular lobes 5 can effectively guide and mix the airflow from the outer and inner ducts.

[0036] In this embodiment, the rectangular alternating mixer is equipped with a total of 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 their angle with the horizontal plane is designed to be 5 to 20 degrees according to actual needs. The rectangular lobes of the inner duct are alternately and evenly distributed 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 with the horizontal plane is designed to be 5 to 25 degrees, and the angle of the long rectangular lobes 5 of the rectangular alternating mixer with the horizontal plane is 10 to 40 degrees. 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 degrees. 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 degrees.

[0037] When the variable-cycle engine switches to dual-bypass mode, the large-area regulating valve body 8 and the small-area regulating valve body 9 are positioned directly behind the upper rectangular lobes of the duct. This means that the large-area regulating valve body 8 and the small-area regulating valve body 9 are moved to overlap with the upper rectangular lobes (i.e., the extensions of the long rectangular lobes 5 or the short rectangular lobes 4 of the rectangular alternating mixer in the duct), ensuring that the flow of duct air through the lower rectangular lobes is not obstructed. The area regulating valve body rotates within a range of 0 to 12 degrees. Drive device 7 drives the gear transmission mechanism 6, which in turn drives the rotation of the area regulating valve body, effectively adjusting the flow area.

[0038] When the engine switches to single-outer flow mode, the area-regulating valve body begins to move circumferentially, gradually reducing the flow area between the lower rectangular lobes until the flow path corresponding to the short rectangular lobes 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 path of the short rectangular lobes 4 of the inner rectangular alternating mixer, while the small-area regulating valve body 9 corresponds to and covers the area surrounding the long rectangular lobes 5 of the inner rectangular alternating mixer. Both are evenly distributed at the outer flow outlet of the variable-cycle engine based on the arrangement of the long and short lobes of the rectangular alternating mixer. This forces the outer flow to be completely redirected from the long rectangular lobes 5 of the rectangular alternating mixer into the core area of ​​the inner flow, thereby achieving precise regulation of the outer flow area.

[0039] The lower end of the area-control valve body is fixed in a semicircular slideway on the inner wall of the duct, while the upper end is engaged in a circumferentially movable slideway reserved on the outer wall of the duct. Its exposed portion is designed as a circumferential rack, and rack 10 is tightly meshed with gear transmission mechanism 6. The inclination angle and number of the area-control valve body with respect to the horizontal plane are consistent with those of the rectangular leaflets of the duct, aiming to reduce pressure loss when the duct airflow flows through the gaps between adjacent rectangular leaflets.

[0040] The drive mechanism 7 has forward and reverse rotation capabilities, driving the gear mechanism to rotate clockwise or counterclockwise, which in turn drives the valve body via the circumferential rack structure at the upper end of the area-adjusting valve body. The final position of the valve body is determined by the operating 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 rotate and move 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 leaflet 5 of the rectangular alternating mixer, while the large area regulating valve body 8 accurately covers the short rectangular leaflet 4 of the rectangular alternating mixer. By physically blocking the flow path of the short rectangular leaflet 4 of the rectangular alternating mixer, the outer duct airflow is forced to be redirected to flow through the long rectangular leaflet 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, neither the large area regulating valve body 8 nor the small area regulating valve body 9 interferes with any leaflet 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, due to their high flow field penetration rate, can effectively guide the cold airflow of the outer duct to the core area of ​​the inner duct airflow, 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, ensuring a smooth transition of the airflow. One end of the two valve bodies is flexibly moved through the slide 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] Based on the engine's modal conversion requirements, the drive unit 7 is activated at the appropriate time, precisely controlling the movement of the rack on the outer wall of the duct via the gear transmission mechanism 6. This in turn drives the large-area regulating valve body 8 and the small-area regulating valve body 9 to rotate or translate within a range of 0 to 12 degrees, achieving fine adjustment of the duct's flow area. This design not only optimizes airflow mixing but also significantly improves afterburner combustion efficiency, thereby comprehensively enhancing the engine's overall performance.

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

[0046] Initial State: When the engine is started and in dual bypass mode, both the large-area regulating valve body 8 and the small-area regulating valve body 9 are in their initial positions, not interfering with any of the lobes of the rectangular alternating mixer. At this point, the duct airflow can smoothly pass through the gaps between the lobes of the rectangular alternating mixer, while the duct airflow is guided by the central cone 3 for preliminary mixing with the duct airflow.

[0047] Mode conversion: When the engine needs to convert from dual-external mode to single-external mode, the drive device 7 starts working, driving 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 flow channel corresponding to 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 some flaps 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 single duct mode, precise adjustment of the large-area regulating valve body 8 and the small-area regulating valve body 9 directs the airflow from the duct into the corresponding flow path of the rectangular alternating mixer's long rectangular lobes 5 in the duct, where it is efficiently mixed with the airflow from the duct. Furthermore, the sealing effect of the large-area regulating valve body 8 on the short rectangular lobes 4 of the rectangular alternating mixer prevents unnecessary airflow loss and interference.

[0049] During the entire process, the engine control system can adjust and optimize the drive device 7 and the gear transmission mechanism 6 based on 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] This invention successfully implements a variable-area rear duct ejector with a controllable alternating airflow structure for a variable-cycle engine. By precisely controlling the movement of the large-area regulating valve body 8 and the small-area regulating valve body 9, as well as the arrangement and angle design of the rectangular alternating mixer, this ejector efficiently manages and optimizes the engine's airflow in different modes.

[0051] Figure 1 This 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 positions 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 valve bodies of the variable area rear duct ejector in the dual outer duct mode of the controllable airflow alternating structure. In the dual outer duct mode of the variable cycle engine, 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 leaflet 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 used for area regulation. The driving device drives the valve body to rotate in the circumferential direction to realize the change of its spatial position. It cooperates with the rectangular alternating mixer to change the flow area of ​​the outer duct. Figure 5The rectangular alternating mixer generates a directional vortex structure when the airflow flows through it. Because the intensity and range of the directional vortices generated by the long and short rectangular blades are inconsistent, the interaction between the long and short adjacent directional vortices promotes the mixing of the inner and outer airflows over a larger range, making the inner and outer airflows more evenly mixed, 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. This further improves the conditions at the inlet of the afterburner, increases the efficiency of the afterburner, and thus enhances the performance of the entire variable cycle engine. The design of the rectangular alternating mixer allows the directional vortices generated by the long and short rectangular blades to differ in intensity and range. This difference promotes the interaction between adjacent directional vortices, thereby promoting the mixing of the inner and outer airflows over a larger range.

[0053] Compared with the existing rear duct ejector area adjustment scheme, the present invention adopts a rectangular alternating mixer and is equipped with a matching large and small area adjustment valve body. 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 through the long leaflet into the inner duct. 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. 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 in the single outer duct mode of single outer duct, the outer duct airflow passes through the long rectangular leaflet into the inner duct and mixes with the inner duct airflow. Due to the presence of long rectangular leaflets, the alternating mixer has a higher penetration rate in the inner duct than the general moment mixer and wave lobe mixer. It can send 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 an 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 should not 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 patent 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, each of which is divided into short rectangular lobes and long rectangular lobes. These lobes are arranged around a central cone and extend to the inner and outer ducts. The rectangular alternating mixer is equipped with a total of 36 rectangular lobes, 18 of which are located in the outer duct and the other 18 in the inner duct. The lobes in the outer duct are evenly distributed, while the rectangular lobes in the inner duct are alternately and evenly distributed, consisting of 9 long rectangular lobes and 9 short rectangular lobes. 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 tract; A driving device, used for providing power to drive the gear transmission mechanism and the area regulating valve body; The gear transmission mechanism is 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-adjusting valve body of the rear duct ejector to the horizontal direction, the inner and outer duct inclination angles of the rectangular leaves of the rectangular alternating mixer, and the number, width, shape and geometric distribution of the area-adjusting valve bodies; In single-outer duct mode, the area control valve body evenly distributes the long rectangular lobes and short rectangular lobes of the rectangular alternating mixer at the outer duct outlet of the variable cycle engine according to the distribution pattern that the large-area control valve body corresponds to the short rectangular lobes inside, and the small-area control valve body corresponds to the long rectangular lobes inside. When the variable cycle engine is in dual-outer duct mode, the area control valve body overlaps with the rectangular lobes on the rectangular alternating mixer, without affecting the circulation of the outer duct airflow. The rotation angle of the area control valve body is 0 to 12 degrees, and the rotation drive device drives the gear transmission mechanism to rotate, thereby driving the rotation of the area control valve body to achieve area adjustment. When the variable cycle engine is in the dual-outer duct mode, the area of ​​the outer duct is at its largest state, and the large-area regulating valve body and the small-area regulating valve body coincide with the upper rectangular leaflet located in the outer duct, ensuring that the flow of the outer duct airflow through the lower rectangular leaflet is not hindered. At this time, the area adjustment mechanism will not cause any unnecessary pressure loss to the flow field; when the variable cycle engine switches to the single-outer duct mode, the area adjustment valve body begins to move circumferentially, gradually reducing the flow area between the lower rectangular leaflets until the flow channel corresponding to the short rectangular leaflet of the rectangular alternating mixer is completely closed by the large-area regulating valve body, forcing the outer duct airflow to be completely redirected from the long rectangular leaflet of the rectangular alternating mixer into the core area of ​​the inner duct airflow, thereby realizing precise adjustment of the outer duct area.

2. The variable area rear duct ejector with controllable airflow alternating structure for a variable cycle engine according to claim 1, characterized in that: The angle between the rectangular alternating mixer and the horizontal plane is designed to be 5° to 20° according to actual needs, the angle between the short rectangular lobe of the rectangular alternating mixer and the horizontal plane is designed to be 5° to 25°, and the angle between the long rectangular lobe of the rectangular alternating mixer and the horizontal plane is 10° to 40°. The inclination angle of the long rectangular lobe of the rectangular alternating mixer is always greater than the inclination angle of the short rectangular lobe of the rectangular alternating mixer, and the angle difference between the two does not exceed 20°.

3. The variable area rear duct ejector with controllable airflow alternating structure for a variable cycle engine according to claim 1, 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, which is tightly engaged with the gear transmission mechanism. The inclination angle and number of the area regulating valve body to the horizontal plane are consistent with those of the rectangular leaflets of the outer duct; the inclination angle and number of the area regulating valve body to the horizontal plane are the same as the inclination angle of the rectangular leaflets located in the outer duct to the horizontal, and the outer duct airflow flows into the gap between adjacent rectangular leaflets to reduce pressure loss.

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

6. The variable area rear duct ejector with controllable airflow alternating structure for a variable cycle engine according to claim 1, 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 loss.

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

Images