A two-dimensional convergent-divergent nozzle structure with an area-adjustable second stream and its application

Abstract

The present invention relates to a two-dimensional convergent-divergent nozzle structure and application with an adjustable second stream area, which belongs to the field of aviation engines. The structure includes two second stream nozzles arranged on both sides of the two-dimensional convergent-divergent main nozzle, and the adjacent surfaces of the second stream nozzle and the two-dimensional convergent-divergent main nozzle share a common inner wall surface. The outlet end of the second stream nozzle is coupled with a nozzle throat area adjustment mechanism to match the airflow discharge requirements under different flight conditions. The nozzle throat area adjustment mechanism of the present invention uses a movable adjustment plate to control the throat area of ​​the second stream to adjust the second stream flow rate to adapt to different engine operating conditions, and fully utilizes the advantage of the second stream in reducing noise and infrared radiation intensity to solve the problems in the prior art of the complex nozzle cooling structure, the need to significantly adjust the second stream outlet area when coping with wide flight envelope and complex fighter missions, and the poor performance of the second stream under small outlet area.

Description

Technical Field

[0001] The present invention belongs to the field of aviation engines, and in particular relates to a binary convergent-divergent nozzle structure with an area-adjustable second stream and its application. Background Art

[0002] The dual-element convergent-divergent nozzle has a simple structure, is easy to achieve vector propulsion, and is easy to integrate with the rear fuselage of the aircraft. It has received increasing attention. However, the high temperature of the engine tail nozzle wall greatly limits the service life of the nozzle. In addition, the nozzle wall is a strong radiation source of the exhaust system, and often requires certain cooling treatment to reduce the intensity of infrared radiation and increase the life of the nozzle. Currently, the air film cooling method is mostly used in engineering.

[0003] To improve engine performance and reduce exhaust noise, nozzles employ a secondary flow structure. Existing rectangular, single-sided expansion nozzles with a secondary flow form the secondary flow profile by shifting the primary flow profile downward. However, for aircraft with wide flight envelopes and complex, diverse missions, targeted operating modes are required to maximize the performance requirements of different missions. This places higher aerodynamic demands on the engine's secondary flow, requiring greater adjustability and mission adaptability to balance the ratio of the primary and secondary flows under varying operating conditions to achieve optimal thrust performance. However, the wide flight envelope requires a high range of adjustment for the secondary flow area, making it difficult to maintain high thrust performance for nozzles with a small exit area.

[0004] Therefore, the present invention designs a two-dimensional convergent-divergent nozzle structure with an area-adjustable second stream, which can achieve supersonic exhaust, reduce the infrared radiation intensity and noise of the nozzle, improve the service life of the nozzle, and maximize the satisfaction of different engine performance requirements for different tasks with higher performance. Summary of the Invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a two-dimensional convergent-divergent nozzle structure with an area-adjustable second stream. The second stream and the two-dimensional convergent-divergent main nozzle share a side wall facing the nozzle wall to cool the nozzle wall to increase the service life of the nozzle and reduce the infrared radiation intensity. A movable adjusting plate is used to control the throat area of ​​the second stream to regulate the second stream flow rate to adapt to different engine operating conditions, and fully utilize the advantage of the second stream in reducing noise and infrared radiation intensity to solve the problems in the prior art that the nozzle cooling structure is complex, the second stream nozzle needs to significantly adjust the second stream outlet area when coping with complex fighter jets with wide flight envelope missions, and the second stream performance is poor under a small outlet area.

[0007] The technical solution of the present invention is: a two-dimensional convergent-divergent nozzle structure with an area-adjustable second stream, comprising two second stream nozzles arranged on both sides of the two-dimensional convergent-divergent main nozzle, and the adjacent surfaces of the second stream nozzle and the two-dimensional convergent-divergent main nozzle are a common inner wall surface; the outlet end of the second stream nozzle is coupled with a nozzle throat area adjustment mechanism to match the airflow discharge requirements under different flight conditions.

[0008] A further technical solution of the present invention is that the two second stream nozzles are symmetrical structures, and their air inlets are at the same axial position as the inlet of the binary convergent section, and high-pressure compressor cooling air is introduced to cool the walls on both sides of the binary convergent-divergent main nozzle.

[0009] A further technical solution of the present invention is: the second stream nozzle includes an outer wall, an upper wall, a lower wall, a common inner wall, and an auxiliary control inner wall located at the outlet end of the channel that constitute its nozzle channel; the auxiliary control inner wall is an inclined plate installed on the common inner wall, and the starting and ending points of its profile are parallel to the axial direction to reduce local losses in the front airflow and control the direction of the outlet airflow. The middle section of its profile is a straight line with an angle of 10° to 30° to the axial direction, and it smoothly transitions to the starting and ending profiles, which is used to assist in controlling the size of the throat area of ​​the second stream nozzle.

[0010] A further technical solution of the present invention is: the nozzle throat area adjustment mechanism includes a movable adjustment plate sealed and adhered to the outer wall, which is controlled by a driving component to be able to move axially, and the minimum distance between the movable adjustment plate and the auxiliary control inner wall is changed by displacement to control the throat area of ​​the second stream nozzle.

[0011] A further technical solution of the present invention is: the curved profile structure of the movable adjustment plate is that the profile lines at the start and end are parallel to the axial direction, the middle section curve is S-shaped, first bending toward the inside of the second stream nozzle to control the throat area, and then bending toward the outside of the second stream nozzle to control the airflow direction; and the middle section has a smooth transition with the start and end sections.

[0012] A further technical solution of the present invention is that the side wall height of the second stream nozzle is greater than the maximum height of the binary convergent section and the binary divergent section of the binary divergent main nozzle, and the inlet and outlet heights are the same to facilitate the forward and backward movement of the adjustment plate.

[0013] A further technical solution of the present invention is that the outlet ends of the upper and lower walls of the second stream nozzle are widened structures, widened to exceed the outermost side of the movable adjustment plate, so as to avoid thrust loss caused by leakage of the jet on the upper and lower sides in front of the outlet when the movable adjustment plate moves.

[0014] A further technical solution of the present invention is: the driving component includes an actuator cylinder installed on the outer wall, and a pull rod connected to the output end of the actuator cylinder, which is used to control the axial movement of the movable adjusting plate; the actuator cylinder is a linear actuator cylinder, which controls the pull rod to move only in the axial direction, and the pull rod is fixedly connected to the movable adjusting plate.

[0015] A further technical solution of the present invention is: the binary convergent and divergent main nozzle includes a circular-to-square section, a binary convergent section, and a binary divergent section; the inlet of the circular-to-square section is the inlet of the binary convergent and divergent main nozzle, which matches the turbine outlet of the engine, and the cross-sectional shape of the circular-to-square section is changed from a circle to a rectangle. The binary convergent section and the binary divergent section only converge and expand in the longitudinal direction of the nozzle, and there is no expansion angle in the transverse direction.

[0016] A binary convergent-divergent nozzle structure with an area-adjustable second flow is applied to the binary convergent-divergent nozzle. Multiple driving components are arranged in parallel on the outer wall surface, and the axial position of the movable adjustment plate is controlled by starting at the same time to ensure sealing and balance during the movement.

[0017] Beneficial effects

[0018] The beneficial effects of the present invention are as follows: the present invention provides a two-dimensional convergent-divergent nozzle structure with an area-adjustable second stream, wherein the two-dimensional convergent-divergent nozzle and the second stream nozzle share a side wall surface, effectively utilizing the second stream of cold air to cool the main nozzle wall surface, thereby improving the service life of the nozzle, and effectively reducing the jet temperature by wrapping the mainstream hot air with the second stream of cold air and mixing it with the mainstream hot air, thereby reducing the infrared radiation intensity and wall noise of the jet, and at the same time, adjusting the throat area of ​​the second stream by axial movement of the movable adjustment plate to meet the requirements of the nozzle for different engine working conditions, regulating the flow rate of the nozzle mainstream and the second stream, and ensuring high thrust performance under a small outlet area, thereby effectively improving the unit thrust and efficiency of the engine.

[0019] The technical difficulty of the present invention lies in the fact that the movable adjustment plate and the auxiliary adjustment inner wall of the second stream nozzle need to be specially designed with profiles, so that the movable adjustment plate can adjust the throat area of ​​the second stream only by axial movement, reducing the difficulty of adjustment. At the same time, the profile needs to be designed to be as smooth as possible to ensure that the aerodynamic performance of the airflow in the second stream nozzle is high. The design of the profile also needs to take into account the overall length of the auxiliary adjustment inner wall, and take into account that the cooling area of ​​the shared inner wall should not be too small. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of a binary convergent-divergent nozzle structure with an area-adjustable second stream, which is optional in an embodiment of the present invention;

[0021] Figure 2This is a schematic diagram of the auxiliary control inner wall surface and the profile of the adjustable movable blade of a binary convergent-divergent nozzle structure with an area-adjustable second stream, which is optional in an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of a small throat area of ​​a second stream of a binary convergent-divergent nozzle structure with an adjustable second stream area, which is optional in an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of a large throat area of ​​a second stream of a binary convergent-divergent nozzle structure with an adjustable second stream area, which is optional in an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the second stream of a common binary nozzle with a small outlet area;

[0025] Figure 6 Schematic diagram of the spray flow of the second stream nozzle with adjustable area implemented by the present invention when the second stream has a small outlet area;

[0026] Explanation of the accompanying symbols: 1. Binary convergent and divergent main nozzle; 2. Second stream nozzle; 3. Movable adjustment plate; 4. Actuator; 5. Pull rod; 11. Circular rotating square section; 12. Binary convergent section; 13. Binary divergent section; 21. Rear widened upper wall; 22. Outer wall; 23. Common inner wall; 24. Auxiliary control inner wall. DETAILED DESCRIPTION

[0027] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] The existing nozzle secondary flow structures have high requirements for the range of second flow area adjustment due to the wide flight envelope, making it difficult to ensure high thrust performance with a small nozzle outlet area. The present invention provides a dual-convergent nozzle structure with an adjustable second flow area, comprising two secondary flow nozzles disposed on either side of a dual-convergent main nozzle, wherein the adjacent surfaces of the secondary flow nozzles and the dual-convergent main nozzle share a common inner wall surface; the outlet end of the second flow nozzle is coupled with a nozzle throat area adjustment mechanism to match the airflow discharge requirements under different flight conditions.

[0030] The present invention can achieve supersonic exhaust, reduce the infrared radiation intensity and noise of the nozzle, increase the service life of the nozzle, and meet the different requirements of engine performance for different tasks to the maximum extent with higher performance.

[0031] The above technical solution is further described below with reference to the accompanying drawings.

[0032] The embodiment of the present invention is a binary convergent-divergent nozzle structure with an adjustable second flow area, such as Figure 1 、 2 As shown in Figures 3 and 4, it includes: a binary convergent and divergent main nozzle 1, a second stream nozzle 2, a movable adjustment plate 3, an actuator 4, a pull rod 5, a circular rotating square section 11, a binary convergent section 12, a binary expansion section 13, a rear widened upper wall 21, an outer wall 22, a common inner wall 23, and an auxiliary control inner wall 24.

[0033] A binary convergent-divergent nozzle structure with an area-adjustable second stream is applied using the technical solution of the present invention. The binary convergent-divergent nozzle and the second stream nozzle share a side wall surface to effectively utilize the second stream of cold air to cool the wall surface, thereby improving the service life of the nozzle. The second stream of cold air wraps the mainstream hot air and mixes with the mainstream hot air to effectively reduce the jet temperature, reduce the infrared radiation intensity and wall noise of the jet, and at the same time, the throat area of ​​the second stream is adjusted by axial movement of the moving adjustment plate to meet the requirements of the nozzle for different engine working conditions, regulate the flow of the nozzle mainstream and the second stream, and effectively improve the unit thrust and efficiency of the engine.

[0034] Reference Figure 1 As shown, the inlet of the circular-to-square section in this example is the inlet of the binary convergent-divergent main nozzle 1, which matches the turbine outlet of the engine. The cross-sectional shape of the circular-to-square section 11 changes from a circle to a rectangle. The binary convergent section 12 and the binary divergent section 13 only converge and diverge in the longitudinal direction of the nozzle, and there is no expansion angle in the transverse direction. The convergence angle of the binary convergent section 12 has a greater influence on the flow coefficient of the nozzle, and the expansion angle of the binary divergent section 13 has a greater influence on the thrust coefficient of the nozzle. Considering the overall performance of the nozzle, the convergence angle of the binary divergent main nozzle 1 is selected to be less than 60°, and the divergence angle is selected to be less than 40°.

[0035] The two secondary flow channels of the second stream nozzle 2 are located on the left and right sides of the binary convergent-divergent main nozzle 1, respectively. Their inlets are located at the same axial position as the inlets of the binary convergent section 21 of the binary convergent-divergent main nozzle 1. The height of the second stream nozzle 2 is greater than the maximum height of the binary convergent section 12 and divergent section 13 of the binary convergent-divergent main nozzle 1 to prevent the mainstream airflow from overflowing from the left and right sides. The inlet and outlet heights of the second stream nozzle 2 are the same, and it shares a side wall surface, namely, the inner wall 23, with the binary convergent-divergent main nozzle 1 to achieve the effect of cooling the side wall surface of the binary convergent-divergent nozzle 1. The outer wall surface 21 is sealed but not fixedly connected to the movable adjustment plate 3, ensuring that the connection does not leak airflow and that the movable adjustment plate 3 can move axially. The rear widened upper / lower wall surface 22 is widened at the rear side, and the widened width is flush with the maximum lateral position of the movable adjustment plate 3 to prevent unnecessary thrust loss caused by airflow ejected from the upper side when the movable adjustment plate 3 moves.

[0036] Reference Figure 2-3 As shown, the auxiliary control inner wall surface 24 is designed with a profile, and the profile at the beginning and end is along the axial direction, so as to reduce the local loss of the front airflow and control the direction of the outlet airflow. The middle curve forms an angle with the axial direction (preferably the angle is 10° to 30°) to assist in controlling the size of the throat area of ​​the second stream nozzle 2. The curved profile of the movable regulating plate 3 is designed with a profile, and the profile at the beginning and end is along the axial direction, and the middle curve is S-shaped, first bending toward the inside of the second stream nozzle 2 to control the throat area, and then bending toward the outside of the second stream nozzle 2 to control the airflow direction. The profile design of the auxiliary control inner wall surface 24 and the movable regulating plate 3 is as shown in FIG. Figure 2 As shown, the movable adjusting plate 3 moves only in the axial direction to change the minimum distance between the movable adjusting plate 3 and the auxiliary control inner wall 24 to control the throat area of ​​the second stream nozzle 2, so as to match the airflow discharge requirements under different flight conditions.

[0037] Reference Figure 1 As shown, the actuator 4 and the pull rod 5 serve as control devices to control the axial movement of the movable adjusting plate 3. The actuator 4 is a linear actuator and is installed on the outside of the end of the outer wall 22. The control pull rod 5 is connected to the output end of the actuator and only moves axially. The end of the pull rod 5 is fixedly connected to the movable adjusting plate 3. Considering the maximum bearing force on each actuator 4 and the pull rod 5 and the uniformity of the force on the movable adjustment 3, each movable adjusting plate 3 can be equipped with multiple sets of actuators 4 and pull rod 5 devices, and they are evenly distributed in the longitudinal direction.

[0038] In an embodiment of the present invention, air flows enter the binary diverging main nozzle 1 and the second stream nozzle 2 respectively. The air flow in the binary diverging main nozzle 1 comes from the high-temperature combustion gas after the turbine, and the air flow in the second stream nozzle 2 mainly comes from the bleed air of the engine front components. The air flow temperature is low, and the shared inner wall 23 is cooled. The cold air of the second stream nozzle 2 wraps the mainstream hot air and mixes with the mainstream hot air to effectively reduce the jet temperature, reduce the infrared radiation intensity and wall noise of the jet, and when the engine needs the second stream nozzle 2 to reduce the flow rate, the actuator 4 and the pull rod 5 control the adjustable adjustment plate 3 to move axially backward, reducing the throat area of ​​the second stream nozzle 2 and thus reducing the flow rate. Figure 3 As shown, when the engine requires the second stream nozzle 2 to increase the flow rate, the actuator 4 and the pull rod 5 control the adjustable adjustment plate 3 to move axially forward, increasing the throat area of ​​the second stream nozzle 2 and thus increasing the flow rate, as shown in FIG. Figure 4 As shown, it meets the exhaust requirements of the engine in different working states. When the outlet area required by the second stream nozzle is small, the jet of the ordinary two-dimensional nozzle is as follows Figure 5 As shown in FIG, the thrust coefficient is 0.97, but when the area-adjustable second stream nozzle in the embodiment of the present invention is used, the thrust coefficient can reach 0.99, and the jet effect is as follows: Figure 6 As shown, the thrust coefficient can be increased by 1%-2% compared with the ordinary two-dimensional nozzle.

[0039] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A dual convergent-divergent nozzle structure with an area-adjustable second stream, characterized by: The invention comprises two second stream nozzles arranged on both sides of the two-dimensional convergent-divergent main nozzle, and the adjacent surfaces of the second stream nozzles and the two-dimensional convergent-divergent main nozzle share a common inner wall surface; the outlet ends of the second stream nozzles are coupled with a second stream nozzle throat area adjustment mechanism to match the airflow discharge requirements under different flight conditions; The two second flow nozzles are symmetrical in structure, and their air inlets are located at the same axial position as the inlet of the two-dimensional convergent section, and introduce high-pressure compressor cold air to cool the walls of both sides of the two-dimensional convergent-divergent main nozzle; The second stream nozzle includes an outer wall, an upper wall, a lower wall, a common inner wall, and an auxiliary control inner wall located at the outlet end of the second stream nozzle channel; the auxiliary control inner wall is an inclined plate mounted on the common inner wall, and the starting and ending points of its profile are parallel to the axial direction to reduce local airflow losses in the front and control the direction of the outlet airflow. The middle section of its profile is a straight line forming an angle of 10° to 30° with the axial direction, and smoothly transitions to the starting and ending profiles, and is used to assist in controlling the throat area of ​​the second stream nozzle; The throat area adjustment mechanism of the second stream nozzle includes a movable adjustment plate sealed against the outer wall surface, and is controlled by a driving component to be axially displaceable. The minimum distance between the movable adjustment plate and the auxiliary control inner wall surface is changed by the displacement to control the throat area of ​​the second stream nozzle. The curved profile structure of the movable adjustment plate is that the profiles at the start and end are parallel to the axial direction, the middle section curve is S-shaped, first bending toward the inside of the second stream nozzle to control the throat area, and then bending toward the outside of the second stream nozzle to control the airflow direction; and the middle section has a smooth transition with the start and end sections.

2. The dual convergent-divergent nozzle structure with an area-adjustable second stream according to claim 1, characterized in that: The side wall height of the second flow nozzle is greater than the maximum height of the binary convergent section and the binary divergent section of the binary divergent main nozzle, and the inlet and outlet heights are the same to facilitate the forward and backward movement of the adjustment plate.

3. The dual convergent-divergent nozzle structure with an area-adjustable second stream according to claim 2, characterized in that: The outlet ends of the upper and lower walls of the second stream nozzle are widened structures, widening to exceed the outermost side of the movable adjustment plate to avoid thrust loss caused by leakage of the jet on the upper and lower sides in front of the outlet when the movable adjustment plate moves.

4. The dual convergent-divergent nozzle structure with an area-adjustable second stream according to claim 3, characterized in that: The driving component includes an actuator cylinder installed on the outer wall of the second stream nozzle, and a pull rod connected to the output end of the actuator cylinder, which is used to control the axial movement of the movable adjustment plate; the actuator cylinder is a linear actuator cylinder, which controls the pull rod to move only in the axial direction, and the pull rod is fixedly connected to the movable adjustment plate.

5. The dual convergent-divergent nozzle structure with an area-adjustable second stream according to claim 1, characterized in that: The binary convergent-divergent main nozzle includes a circular-to-square section, a binary convergent section, and a binary divergent section; the inlet of the circular-to-square section is the inlet of the binary divergent main nozzle, which matches the turbine outlet of the engine, and the cross-sectional shape of the circular-to-square section changes from a circle to a rectangle. The binary convergent section and the binary divergent section only converge and expand in the longitudinal direction of the nozzle, and there is no expansion angle in the transverse direction.

6. A two-dimensional converging-diverging nozzle structure with an area-adjustable second stream according to any one of claims 1 to 5, applied to a two-dimensional converging-diverging nozzle, characterized in that: A plurality of the driving components are arranged in parallel on the outer wall surface, and are started and controlled to control the axial position of the movable adjustment piece at the same time, so as to ensure the sealing and balance during the movement process.

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