Low infrared signature adaptive variable cycle engine plug exhaust system

Abstract

The application belongs to the field of engine exhaust system, and particularly relates to a self-adaptive variable cycle engine plug exhaust system with low infrared characteristic, which comprises an outer engine case, a third engine case, an outer bypass engine case, a booster cylinder, a third channel, an inner bypass engine case, an outer bypass channel, a center cone, an inner bypass channel and a heat shield, and is characterized in that the self-adaptive variable cycle engine plug exhaust system further comprises an outer plug cone, an inner plug cone A, an inner plug cone B, an actuating cylinder A, an adjusting sleeve, an actuating cylinder B, an expansion adjusting sheet, a baffle, a ring sleeve A and a ring sleeve D, wherein the third channel with a closed end is connected with the spindle-shaped outer plug cone located in the middle of the tail nozzle and having an opening at the tail through a plurality of tail branch plates uniformly distributed in the circumferential direction. In the application, the airflow speed behind the main flow throat is high and the pressure is low, and the low-pressure airflow in the third channel is discharged from the airflow outlet of the third channel and mixed with the main flow airflow, so that the temperature of the main flow airflow is reduced and the infrared radiation signal of the tail jet flow is weakened.

Description

Technical Field

[0001] This invention belongs to the field of engine exhaust systems, and particularly relates to an adaptive variable cycle engine plug exhaust system with low infrared signature. Background Technology

[0002] In 2021, the first and only adaptive variable cycle engine to enter the testing phase announced the completion of testing. This engine has two different modes: high thrust and high efficiency. Analysis revealed that this adaptive variable cycle engine also has a maximum thrust-to-weight ratio mode and a conventional turbofan mode. This results in a 25% increase in loiter time, a 25% increase in fuel efficiency, a 35% increase in range, and a 10% increase in thrust for fighter jets equipped with this engine. The test results are consistent with the predictions, indicating that the new generation of foreign fighter jets equipped with the XA100 engine have adaptive variable cycle propulsion capabilities.

[0003] Plug exhaust systems are used in aviation and aerospace fields due to their unique aerodynamic performance. Since the 1950s, research has been conducted on the thrust performance and external drag characteristics of non-adjustable axisymmetric plug nozzles. The results show that plug nozzles have high thrust characteristics when working in a large pressure ratio range. At the same time, in the range of Mach number of the outflow, the drag coefficient of plug nozzles is lower than that of traditional axisymmetric convergent nozzles and axisymmetric divergent nozzles.

[0004] In a plug nozzle, the low-temperature plug cone shields the high-temperature components inside the engine's rear cavity, which helps reduce infrared radiation signature. At the same time, the pressure on the plug nozzle wall is lower than the pressure on the internal high-temperature components, so the required cooling air bleed pressure is lower when cooling measures are taken, and cooling bleed air is easier to implement. This gives plug nozzles a considerable advantage in infrared suppression.

[0005] Domestic and international literature discloses the flow channel configuration of adaptive variable cycle engines with plug-type exhaust systems, but does not specifically disclose the adjustment method of the flow channel. For example, in patent EP1533510B1, the airflow in the third bypass duct is discharged between the outer and inner plug cones, and the flow rate can be adjusted by moving the inner plug cone. The mainstream airflow is discharged from the nozzle, and the mainstream airflow and the third bypass airflow are mixed downstream of the nozzle but not mixed inside the nozzle. This configuration is equivalent to the mainstream airflow and the third bypass airflow being discharged independently. At the same time, the mainstream throat and mainstream outlet are both adjusted by moving the sleeve. This adjustment structure of the mainstream throat and mainstream outlet is much simpler than that of the regulating plate type adjustment.

[0006] The infrared suppression effect of the exhaust system in patent EP1533510B1 is not ideal, specifically in the following two aspects:

[0007] The airflow in the third duct only begins to mix with the mainstream airflow downstream of the nozzle, resulting in a poor cooling effect on the tail jet.

[0008] The main airflow outlet is adjusted by a sleeve. Under different conditions, the exposed size of the plug cone varies greatly, resulting in a stronger infrared signal when more of the plug cone is exposed. The overall infrared suppression effect is unstable and poor.

[0009] This invention designs an adaptive variable cycle engine plug exhaust system with low infrared signature to solve the above problems. Summary of the Invention

[0010] To address the aforementioned deficiencies in the prior art, this invention discloses an adaptive variable cycle engine plug exhaust system with low infrared signature, which is implemented using the following technical solution.

[0011] An adaptive variable cycle engine plug exhaust system with low infrared signature includes an outer plug cone, an inner plug cone A, an inner plug cone B, an actuator A, an adjusting sleeve, an actuator B, an expansion adjusting plate, a baffle plate, a ring sleeve A, and a ring sleeve D. A third duct, closed at its end, is connected to a spindle-shaped outer plug cone located in the center of the exhaust nozzle and open at its tail end via several circumferentially evenly distributed tail support plates. An inner plug cone A, forming an annular throat of the third duct, is supported and installed inside the outer plug cone. An inner plug cone B, which adjusts the throat and outlet area of ​​the third duct under the drive of the actuator A, slides axially sealed within the inner plug cone A. The third duct is equipped with a... The inner ring D has an axially sealed sliding mechanism driven by four circumferentially evenly distributed actuators B, which is used to adjust the main flow throat. The adjusting sleeve has a telescopic structure between itself and the end of the third duct that does not obstruct the main flow. The end of the ring D is hinged with several circumferentially evenly distributed expansion adjustment plates that adjust the nozzle exit area. The end of the inner ring A of the outer casing has several baffles that correspond one-to-one with the expansion adjustment plates. The end of each baffle is hinged to the end of the corresponding expansion adjustment plate. The ring D and the expansion adjustment plates have a structure that drives the expansion adjustment plates to swing synchronously inward or outward.

[0012] As a further improvement of this technology, a connecting rod A is hinged to the fixed rod on the outer side of the expansion adjustment plate, and a connecting rod B is hinged to the end of the connecting rod A. The connecting rod B is hinged to the actuating ring A nested and sliding in the ring sleeve D. The actuating ring A is driven by four actuating cylinders C that are circumferentially and evenly installed on the outer side of the ring sleeve D.

[0013] As a further improvement to this technology, an actuating ring B is installed on the outer side of the adjusting sleeve, and the actuating ring B is driven by four actuating cylinders B evenly distributed circumferentially on the inner side of the ring sleeve D.

[0014] As a further improvement to this technology, the adjusting sleeve has an axially sealed sliding ring B, and the ring C at the end of the third duct slides on the ring B, with the ring B and the ring C forming a telescopic structure.

[0015] As a further improvement to this technology, the inner side of the outermost expansion adjustment piece in all the expansion adjustment pieces has a locking piece that cooperates with the adjacent expansion adjustment pieces on both sides.

[0016] As a further improvement to this technology, the inner side of the outermost baffle in all the baffles has a locking tab that cooperates with the adjacent baffles on both sides.

[0017] As a further improvement to this technology, the tail opening end of the outer plug cone is circumferentially uniformly distributed with lobes that increase the mixing degree between the third duct airflow and the mainstream.

[0018] As a further improvement to this technology, the angle between the central axis of the tail support plate and the generatrix of the front end of the outer plug cone is 60-90 degrees.

[0019] As a further improvement to this technology, the angle between the front generatrix of the spindle-shaped outer plug cone and its axis is 30 degrees.

[0020] As a further improvement to this technology, the angle between the rear generatrix of the spindle-shaped outer plug cone and its axis is 20 degrees.

[0021] Compared to traditional aircraft engine exhaust systems, the airflow behind the main jet throat in this invention has a high speed and low pressure. The low-pressure airflow in the third duct mixes with the main jet after being discharged from the third duct outlet, thereby reducing the temperature of the main jet and weakening the infrared radiation signal of the tail jet.

[0022] The outer plug cone, inner plug cone A, and inner plug cone B in this invention not only provide the fighter jet engine with good infrared suppression but also good high-altitude characteristics. The outer plug cone, inner plug cone A, and inner plug cone B effectively shield high-temperature components such as the center cone or turbine, thereby reducing the infrared radiation from these components. Simultaneously, the outer plug cone, inner plug cone A, and inner plug cone B, which shield high-temperature components such as the center cone or turbine, themselves become new sources of infrared radiation. Because they are located at the nozzle where the airflow velocity is high and the static pressure is low, they are cooled by the low-pressure cold air, achieving the effect of effectively suppressing the infrared radiation from the outer plug cone, inner plug cone A, and inner plug cone B.

[0023] This invention adjusts the size of the main flow throat by adjusting the movement of the sleeve along the axial direction of the nozzle, making the main flow throat adjustment structure simpler. The nozzle exit size in this invention is adjusted by the swinging of the expansion adjustment plate, ensuring that the exposed size of the inner plug cone B does not change significantly during nozzle exit adjustment, thereby minimizing the change in the infrared radiation signal of the inner plug cone B and improving the overall infrared suppression effect of the engine.

[0024] The adjustment methods for the main throat and the nozzle outlet in this invention are implemented with a relatively simple structure, so that this invention has a stable infrared suppression effect.

[0025] In this invention, when the airflow in the third duct passes through the outer plug cone, it cools the outer plug cone and wraps around the inner plug cone A and inner plug cone B, thereby reducing the infrared radiation signal of the outer plug cone, inner plug cone A and inner plug cone B.

[0026] This invention has a simple structure and good performance. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional view of the present invention and its overall structure.

[0028] Figure 2 This is a schematic cross-sectional view of the structure at the nozzle exit of the present invention.

[0029] Figure 3 This is a schematic diagram of the distribution of the expansion adjustment plate and baffle.

[0030] Figure 4 This is a schematic diagram of the expansion adjustment plate's operation.

[0031] Figure 5 This is a schematic diagram of the cross-section of the outer plug cone.

[0032] Figure 6 It is a cross-sectional schematic diagram of the cooperation between adjacent expansion adjustment plates and adjacent baffles.

[0033] The labels in the diagram are as follows: 1. Outer casing; 2. Third casing; 3. Outer duct casing; 4. Power cylinder; 5. Third duct; 6. Inner casing; 7. Outer duct; 8. Center cone; 9. Inner duct; 10. Heat shield; 11. Tail support plate; 12. Outer plug cone; 13. Lobe; 14. Support; 15. Inner plug cone A; 16. Inner plug cone B; 17. Actuator A; 18. Adjusting sleeve; 19. Actuator B; 20. Expansion adjusting plate; 21. Locking plate; 22. Fixed rod; 23. Connecting rod A; 24. Connecting rod B; 25. Actuating ring A; 26. Actuating cylinder C; 27. Baffle; 28. Ring sleeve A; 29. ​​Ring sleeve B; 30. Ring sleeve C; 31. Ring sleeve D; 32. Actuating ring B. Detailed Implementation

[0034] The accompanying drawings are schematic diagrams illustrating embodiments of the present invention to facilitate understanding of the structural operating principle. Specific product structures and dimensions can be determined based on the usage environment and conventional technologies.

[0035] like Figure 1 , 2 As shown in Figure 4, it also includes an outer plug cone 12, an inner plug cone A15, an inner plug cone B16, an actuating cylinder A17, an adjusting sleeve 18, an actuating cylinder B19, an expansion adjusting plate 20, a baffle plate 27, a ring sleeve A28, and a ring sleeve D31, wherein... Figure 1 , 2 As shown, the third duct 5, which is closed at its end, is connected to a spindle-shaped outer plug cone 12 located in the middle of the tail nozzle and open at its tail end through several circumferentially evenly distributed tail support plates 11. An inner plug cone A15, forming an annular throat of the third duct 5, is supported and installed inside the outer plug cone 12. An inner plug cone B16, which is axially sealed and slides within the inner plug cone A15, adjusts the throat and outlet area of ​​the third duct 5 under the drive of the actuating cylinder A17. Figure 1 , 2 As shown in Figure 4, an adjusting sleeve 18, driven by four circumferentially evenly distributed actuating cylinders B19 and used to adjust the main flow throat, is axially sealed and slidable inside the ring sleeve D31 installed at the end of the third duct 5. The adjusting sleeve 18 has a telescopic structure between it and the end of the third duct 5 that does not obstruct the main flow; several circumferentially evenly distributed expansion adjusting plates 20 are hinged to the end of the ring sleeve D31 to adjust the nozzle exit area; as shown in Figure 4. Figure 3 , 4 As shown in Figure 6, the end of the axially sealing sliding ring A28 at the end of the outer casing 1 is hinged with several baffles corresponding to the expansion adjustment plate 20. The end of each baffle 27 is hinged to the end of the corresponding expansion adjustment plate 20. The ring D31 and the expansion adjustment plate 20 have a structure that drives the expansion adjustment plate 20 to swing synchronously in a contracting or expanding manner.

[0036] like Figure 2 , 4 As shown, a connecting rod A23 is hinged to the fixed rod 22 on the outer side of the expansion adjustment plate 20, and a connecting rod B24 is hinged to the end of the connecting rod A23. The connecting rod B24 is hinged to the actuating ring A25 nested and sliding on the ring sleeve D31. The actuating ring A25 is driven by four actuating cylinders C26 that are circumferentially and evenly installed on the outer side of the ring sleeve D31.

[0037] like Figure 2 , 4 As shown, an actuating ring B32 is installed on the outer side of the adjusting sleeve 18, and the actuating ring B32 is driven by four actuating cylinders B19 that are evenly distributed circumferentially on the inner side of the ring sleeve D31.

[0038] like Figure 2 , 4As shown, the adjusting sleeve 18 has an axially sealed sliding ring B29 inside, and the ring C30 at the end of the third duct 5 is nested and slidable on the ring B29. The rings B and C form a telescopic structure.

[0039] like Figure 3 , 6 As shown, the inner side of the outermost expansion adjustment piece 20 has a locking piece 21 that cooperates with the adjacent expansion adjustment pieces 20 on both sides.

[0040] like Figure 3 , 6 As shown, the outermost baffle 27 has a locking piece 21 on its inner side that cooperates with the adjacent baffles 27 on both sides.

[0041] like Figure 2 , 4 As shown in Figure 5, the outer plug cone 12 has lobes 13 evenly distributed circumferentially at the tail opening end to increase the mixing degree between the third duct airflow and the mainstream.

[0042] like Figure 4 As shown, the angle between the central axis of the tail support plate 11 and the generatrix of the front end of the outer plug cone 12 is 60-90 degrees.

[0043] like Figure 4 As shown, the angle between the front generatrix of the spindle-shaped outer plug cone 12 and its axis is 30 degrees.

[0044] like Figure 4 As shown, the angle between the rear generatrix of the spindle-shaped outer plug cone 12 and its axis is 20 degrees.

[0045] The workflow of this invention: Different flight states of a fighter jet have different requirements for the engines it is equipped with. The engines themselves adjust the airflow throat and airflow outlet area of ​​their exhaust systems to meet the different flight state requirements of the fighter jet.

[0046] In the aircraft engine, the airflow from the inner duct 9 and the airflow from the outer bypass duct 7 mix in the afterburner 4 to form the mainstream airflow. The mainstream airflow exits through the annular mainstream throat formed between the outer plug cone 12 and the regulating sleeve 18, and through the outlet formed by the outer plug cone 12 and the expansion regulating vane 20. Meanwhile, the airflow in the third bypass duct 5 enters the outer plug cone 12 through the tail support plate 11 and exits through the throat formed between the inner plug cone A15 and the outer plug cone 12, and through the outlet formed by the inner plug cone B16 and the upper lobe 13 of the outer plug cone 12. The exited airflow from the third bypass duct 5 is mixed in the space between the inner plug cone B16 and the expansion regulating vane 20 at the nozzle tail and exits from the nozzle tail.

[0047] This invention adjusts the throat and outlet area of ​​the third duct 5 by activating actuator A17 to drive the inner plug cone B16 axially relative to the inner plug cone A15. It also adjusts the main flow throat by activating four actuators B19 to drive the adjusting sleeve 18 axially relative to the outer plug cone 12. Furthermore, it adjusts the angle between the expanding adjusting plate 20 and the central axis by activating actuator C26 to drive the expanding adjusting plate 20 to swing, thereby adjusting the outlet area of ​​the main flow. The adjustment of the main flow outlet area by the expanding adjusting plate 20 ensures minimal change in the exposed dimensions of the inner plug cone B16, thus minimizing changes in the infrared radiation signal of the inner plug cone B16.

[0048] In summary, the beneficial effects of the present invention are as follows: the airflow behind the main throat is fast and low pressure. After the low-pressure airflow in the third duct 5 is discharged from the airflow outlet of the third duct 5, it mixes with the main airflow, thereby reducing the temperature of the main airflow and weakening the infrared radiation signal of the tail jet.

[0049] The outer plug cone 12, inner plug cone A15, and inner plug cone B16 in this invention not only provide the fighter jet engine with good infrared suppression but also good high-altitude characteristics. The outer plug cone 12, inner plug cone A15, and inner plug cone B16 effectively shield high-temperature components such as the center cone 8 or turbine, thereby reducing the infrared radiation from these components. Simultaneously, the outer plug cone 12, inner plug cone A15, and inner plug cone B16, which shield the center cone 8 or turbine and other high-temperature components, themselves become new sources of infrared radiation. Because they are located at the nozzle where the airflow velocity is high and the static pressure is low, the outer plug cone 12, inner plug cone A15, and inner plug cone B16 are cooled by the low-pressure cold air, achieving the effect of effectively suppressing the infrared radiation of the outer plug cone 12, inner plug cone A15, and inner plug cone B16.

[0050] This invention adjusts the size of the main flow throat by adjusting the movement of the sleeve 18 along the axial direction of the nozzle, making the main flow throat adjustment structure simpler. The nozzle exit size in this invention is adjusted by the swinging of the expansion adjustment plate 20, ensuring that the exposed size of the inner plug cone B16 does not change significantly during nozzle exit adjustment, thereby minimizing the change in the infrared radiation signal of the inner plug cone B16 and improving the overall infrared suppression effect of the engine.

[0051] The adjustment methods for the main throat and the nozzle outlet in this invention are implemented with a relatively simple structure, so that this invention has a stable infrared suppression effect.

[0052] In this invention, when the airflow in the third duct 5 passes through the outer plug cone 12, it cools the outer plug cone 12 and wraps around the inner plug cone A15 and the inner plug cone B16, thereby reducing the infrared radiation signal of the outer plug cone 12, the inner plug cone A15 and the inner plug cone B16.

Claims

1. A low-infrared-signature adaptive variable-cycle engine plug exhaust system, comprising an outer casing, a third casing, an outer bypass casing, an afterburner, a third bypass duct, an inner casing, an outer bypass duct, a center cone, an inner duct, and a heat shield, characterized in that: It also includes an outer plug cone, inner plug cone A, inner plug cone B, actuating cylinder A, adjusting sleeve, actuating cylinder B, expansion adjusting plate, baffle plate, ring sleeve A, and ring sleeve D. The third duct, closed at its end, is connected to a spindle-shaped outer plug cone located in the middle of the tail nozzle and open at its tail end via several circumferentially evenly distributed tail support plates. The inner plug cone A, forming an annular throat with the outer plug cone, is supported and installed inside the outer plug cone. The inner plug cone B, which adjusts the throat and outlet area of ​​the third duct under the drive of actuating cylinder A, slides axially within the inner plug cone A in a sealing manner. The ring sleeve D installed at the end of the third duct slides axially in a sealing manner. There is an adjusting sleeve driven by four circumferentially evenly distributed actuators B, which is used to adjust the main flow throat. The adjusting sleeve has a telescopic structure between itself and the end of the third duct that does not obstruct the main flow. The end of the ring sleeve D is hinged with several circumferentially evenly distributed expansion adjusting plates that adjust the nozzle exit area. The end of the ring sleeve A, which is axially sealed and sliding inside the end of the outer casing, is hinged with several baffles that correspond one-to-one with the expansion adjusting plates. The end of each baffle is hinged to the end of the corresponding expansion adjusting plate. The ring sleeve D and the expansion adjusting plates have a structure that drives the expansion adjusting plates to swing synchronously inward or outward.

2. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: A connecting rod A is hinged to the fixed rod on the outside of the expansion adjustment plate, and a connecting rod B is hinged to the end of the connecting rod A. The connecting rod B is hinged to the actuating ring A, which is nested and slides on the ring sleeve D. The actuating ring A is driven by four actuating cylinders C that are circumferentially and evenly installed on the outside of the ring sleeve D.

3. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: An actuating ring B is installed on the outside of the adjusting sleeve, and the actuating ring B is driven by four actuating cylinders B evenly distributed circumferentially inside the ring sleeve D.

4. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: The adjusting sleeve has an axially sealed sliding ring B inside, and the ring C at the end of the third duct slides nested on the ring B. The ring B and the ring C form a telescopic structure.

5. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: All of the expansion adjustment plates described herein have locking tabs on their inner sides that cooperate with the adjacent expansion adjustment plates on both sides.

6. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: All of the baffles described herein have locking tabs on their inner sides that cooperate with the adjacent baffles on both sides.

7. The low-infrared adaptive variable cycle engine plug exhaust system according to claim 1, characterized in that: The outer plug cone has lobes evenly distributed circumferentially at its tail opening end to increase the mixing degree between the third duct airflow and the mainstream.

8. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: The angle between the central axis of the tail support plate and the generatrix of the front end of the outer plug cone is 60-90 degrees.

9. The low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: The angle between the front generatrix of the spindle-shaped outer plug cone and its axis is 30 degrees.

10. A low-infrared-signature adaptive variable-cycle engine plug exhaust system according to claim 1, characterized in that: The angle between the rear generatrix of the spindle-shaped outer plug cone and its axis is 20 degrees.

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