Method and device for reducing resistance of exhaust nozzle in injection mode in front of exhaust nozzle

Abstract

The invention discloses a method and device for reducing resistance of an exhaust nozzle in an injection mode in front of the exhaust nozzle. The device is located between a combustion chamber and a single-side expansion nozzle. The front end of the tail spraying embedded plate is hinged to the upper side wall of the rear end of the combustion chamber, and the rear end of the tail spraying embedded plate is close to the expansion face of an inlet of the single-side expansion spraying pipe; the front end of the lower wall face adjustable plate is hinged to the lower side wall of the rear end of the combustion chamber, and the rear end of the lower wall face adjustable plate is close to the lower wall face of the single-side expansion spray pipe inlet. The driving mechanism is used for driving the tail spraying embedding plate and the lower wall surface adjustable plate to rotate by taking the corresponding hinge point as the center, so that the tail spraying embedding plate and the lower wall surface adjustable plate are matched with each other and adapt to the incoming flow speed; flow separation around the single-side expansion spray pipe can be reduced, so that the total resistance is reduced, and when the Mach number is increased, the tail spray embedded plate and the lower wall surface adjustable plate can be regulated and controlled by the servo motor to continuously expand so as to adapt to expansion ratios of different modes.

Description

Technical Field

[0001] The present invention belongs to the field of rocket-based combined cycle engines, and particularly relates to a method and device for reducing the drag of a nozzle in an ejector mode before the nozzle. Background Art

[0002] The nozzle is an important component in an engine. For the subsonic combustion ramjet mode, the air flow is decelerated and compressed before entering the combustion chamber, and after combustion, the air flow is discharged at supersonic speed. The nozzle needs to control the exhaust direction and optimize the momentum conversion. In the supersonic combustion ramjet mode, the air flow remains supersonic in the combustion chamber. The nozzle must effectively guide the ultra-high speed and high-temperature exhaust flow, avoid flow separation and maximize the thrust.

[0003] The main function of the nozzle is to accelerate the high-temperature and high-pressure gas discharged from the combustion chamber and generate a backward thrust. Since the RBCC engine needs to handle different flow conditions and combustion characteristics, the nozzle must have the ability of dynamic adjustment. In the low-speed stage (ejector mode), the gas flow velocity is relatively low, and a smaller expansion ratio is required to maintain the thrust. In the hypersonic stage (supersonic combustion ramjet mode) or rocket mode, the air flow velocity is extremely high, and a larger expansion ratio is required to maximize the kinetic energy conversion efficiency of the exhaust. At the same time, the characteristics of the air flow (subsonic, supersonic and hypersonic) are different in different modes, and the nozzle shape must be able to avoid flow separation or pressure fluctuations. Moreover, the nozzle also needs to adapt to different combustion modes. In the rocket mode, the nozzle needs to completely close the intake channel and only handle the rocket combustion exhaust. In the air-breathing mode (ramjet and supersonic combustion ramjet modes), the nozzle needs to consider the flow and combustion expansion of the mixed air flow.

[0004] At present, the variable nozzle plays a central role in multi-modal propulsion systems. For example, the nozzle of NASA's X-43A hypersonic aircraft uses a multi-section sliding variable nozzle. X-43A is an experiment of NASA's hypersonic aircraft, and its RBCC engine combines rocket propulsion and ramjet propulsion technologies. During flight, the engine switches between different operating modes according to the flight phase. To adapt to different speeds, the RBCC engine is equipped with an adjustable nozzle system, including a design similar to a multi-section sliding nozzle. This adjustable nozzle helps optimize flight efficiency, especially during high-speed and hypersonic flights. By adjusting the expansion and contraction of the nozzle, it ensures that the engine can maintain the best thrust and combustion efficiency at different stages. There are also multi-lobe nozzles that can be applied to multi-modal propulsion systems. A multi-lobe nozzle usually consists of multiple adjustable nozzle parts, each of which can be controlled individually, enabling more precise adjustment of the engine's thrust and jet direction. Such a design helps improve the engine's efficiency, especially under high-speed and hypersonic flight conditions. The UK's SABRE engine uses a multi-lobe nozzle to adapt to flight phases from subsonic to hypersonic. This nozzle design not only achieves efficient thrust but also helps optimize aerodynamic performance, especially at different speeds. However, these designs have greatly increased the maintenance cost and adjustment difficulty of the nozzle. At the same time, such complex structures and the application of high-temperature-resistant materials may lead to an increase in the weight of the tail nozzle, thereby affecting the thrust-to-weight ratio of the engine. If a fixed expansion channel is used to simplify the structure, there may be problems such as sudden thrust changes or mismatches during cross-modal transitions. Summary of the Invention

[0005] The object of the present invention is to provide a method and device for reducing the drag of the tail nozzle in the ejector mode before the tail nozzle to solve the problem of excessive under-expanded drag of the tail nozzle in the ejector mode.

[0006] The present invention adopts the following technical solutions: A device for reducing the drag of the tail nozzle in the ejector mode before the tail nozzle, and the device is located between the combustion chamber and the single-sided expansion nozzle;

[0007] The device includes:

[0008] A tail nozzle fitting plate, whose front end is hinged to the upper side wall of the rear end of the combustion chamber, and whose rear end is arranged close to the expansion surface of the single-sided expansion nozzle inlet;

[0009] A lower wall adjustable plate, whose front end is hinged to the lower side wall of the rear end of the combustion chamber, and whose rear end is arranged close to the lower wall surface of the single-sided expansion nozzle inlet;

[0010] A driving mechanism for driving the tail nozzle fitting plate and the lower wall adjustable plate to rotate around the corresponding hinge points, so that the tail nozzle fitting plate and the lower wall adjustable plate cooperate with each other and adapt to the oncoming flow velocity.

[0011] Furthermore, the driving mechanism includes:

[0012] A first servo motor, located above the combustion chamber, whose movable end is hinged with a first transmission rod, and the first transmission rod is hinged with the upper side of the tail nozzle fitting plate, thereby facilitating the first servo motor to drive the tail nozzle fitting plate to rotate.

[0013] Furthermore, the driving mechanism includes:

[0014] A second servo motor, located above the combustion chamber, whose movable end is hinged with a second transmission rod, and the second transmission rod is hinged with the lower side of the lower wall adjustable plate, thereby facilitating the second servo motor to drive the lower wall adjustable plate to rotate.

[0015] Furthermore, the ratio of the outlet area of the single-sided expansion nozzle to the outlet area of the combustion chamber is 2 - 3.

[0016] Furthermore, the initial expansion angle of the single-sided expansion nozzle is 15° - 25°.

[0017] Furthermore, the tail nozzle fitting plate and the lower wall adjustable plate are the same rectangle. The long sides of the tail nozzle fitting plate and the lower wall adjustable plate are arranged along the airflow direction. The length of the tail nozzle fitting plate and the lower wall adjustable plate is equal to the height of the combustion chamber, and its width is equal to the width of the combustion chamber outlet.

[0018] Furthermore, when the Mach number is in the range of (0, 1.2], the tail nozzle fitting plate rotates downward and the angle with the lower wall of the single-sided expansion nozzle is 18°, and the lower wall adjustable plate rotates upward and the angle with the lower wall of the single-sided expansion nozzle is 16°.

[0019] Furthermore, when the Mach number is in the range of (1.2, 2], the tail nozzle fitting plate rotates upward and the angle with the lower wall of the single-sided expansion nozzle is 25°, and the lower wall adjustable plate rotates upward and the angle with the lower wall of the single-sided expansion nozzle is 16°.

[0020] Furthermore, when the Mach number > 2, the tail nozzle fitting plate rotates upward and the angle with the lower wall of the single-sided expansion nozzle is 25°, and the lower wall adjustable plate rotates downward and the angle with the lower wall of the single-sided expansion nozzle is 0°.

[0021] A method for reducing the drag of the tail nozzle in the ejector mode before the tail nozzle, including:

[0022] When the Mach number is in the range of (0, 1.2], drive the first servo motor to drive the tail nozzle fitting plate to rotate downward until the angle with the lower wall of the single-sided expansion nozzle is 18°. At the same time, drive the second servo motor to drive the lower wall adjustable plate to rotate upward until the angle with the lower wall of the single-sided expansion nozzle is 16°;

[0023] When the Mach number is in the range of (1.2, 2], drive the first servo motor to drive the tail nozzle fitting plate to rotate upward until the angle with the lower wall surface of the single-sided expansion nozzle is 25°, and keep the angle between the adjustable plate of the lower wall surface and the lower wall surface of the single-sided expansion nozzle at 16°;

[0024] When the Mach number > 2, keep the angle between the tail nozzle fitting plate and the lower wall surface of the single-sided expansion nozzle at 25°, and drive the second servo motor to drive the adjustable plate of the lower wall surface to rotate downward until the angle with the lower wall surface of the single-sided expansion nozzle is 0°.

[0025] The beneficial effects of the present invention are:

[0026] The present invention can reduce the flow separation around the single-sided expansion nozzle, thereby reducing the total drag. When the Mach number increases, the tail nozzle fitting plate and the adjustable plate of the lower wall surface will continuously expand through the regulation of the servo motor to adapt to different modal expansion ratios, reduce the flow separation around the single-sided expansion nozzle, and reduce the under-expanded drag of the tail nozzle in the ejector mode;

[0027] The present invention realizes the reduction of the under-expanded drag of the single-sided expansion nozzle in the ejector mode by rotating the tail nozzle fitting plate and the adjustable plate of the lower wall surface, and can make the single-sided expansion nozzle reach the required expansion ratio in different modes, which is simple and effective;

[0028] The present invention uses a servo motor to control the tail nozzle fitting plate and the adjustable plate of the lower wall surface, which can accurately position to the specified position with extremely small error, and has a fast response speed. It can complete startup, acceleration, and deceleration in a very short time, and is suitable for scenarios with high-frequency start-stop and high-precision control. Description of the Drawings

[0029] Figure 1 Shows the state of the single-sided expansion nozzle of the present invention in the ejector mode with Ma from 0 to 1.2;

[0030] Figure 2 Shows the state of the single-sided expansion nozzle of the present invention in the ejector mode with Ma from 1.2 to 2;

[0031] Figure 3 Shows the state of the single-sided expansion nozzle of the present invention in the ejector mode with Ma from 2 to 10;

[0032] Figure 4 Shows the Ma diagram of the present invention when the incoming flow Mach number is 0;

[0033] Figure 5 Shows the Pa diagram of the present invention when the incoming flow Mach number is 0;

[0034] Figure 6 Shows the Ma diagram of the present invention when the incoming flow Mach number is 1.6;

[0035] Figure 7 This is the Pa diagram when the incoming flow Mach number of the present invention is 1.6;

[0036] Figure 8 This is the Ma diagram when the incoming flow Mach number of the present invention is 6;

[0037] Figure 9 This is the Pa diagram when the incoming flow Mach number of the present invention is 6.

[0038] Wherein: 10, combustion chamber; 11, single-sided expansion nozzle; 12, tail nozzle fitting plate; 13, lower wall adjustable plate; 14, first servo motor; 15, first transmission rod; 16, second servo motor; 17, second transmission rod. Specific embodiments

[0039] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0040] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more. The "orientation" in the present invention is described based on the orientation of the present invention when it is in the Figure 1 state.

[0041] The present invention discloses a device for reducing the drag of a tail nozzle in an ejector mode before the tail nozzle, as Figure 1-3 shown, the device is located between the combustion chamber 10 and the single-sided expansion nozzle 11.

[0042] The device includes: a tail nozzle fitting plate 12, a lower wall adjustable plate 13, and a driving mechanism.

[0043] The front end of the tail nozzle fitting plate 12 is hinged to the upper side wall of the rear end of the combustion chamber 10, and the rear end of the tail nozzle fitting plate 12 is arranged close to the expansion surface at the entrance of the single-sided expansion nozzle 11.

[0044] The front end of the lower wall adjustable plate 13 is hinged to the lower side wall of the rear end of the combustion chamber 10, and the rear end of the lower wall adjustable plate 13 is arranged close to the lower wall at the entrance of the single-sided expansion nozzle 11.

[0045] The driving mechanism is used to drive the tail nozzle fitting plate 12 and the lower wall adjustable plate 13 to rotate around the corresponding hinge points, so that the tail nozzle fitting plate 12 and the lower wall adjustable plate 13 cooperate with each other and adapt to the oncoming flow velocity.

[0046] The driving mechanism includes: a first servo motor 14, the first servo motor 14 is located above the combustion chamber 10, the movable end of the first servo motor 14 is hinged with a first transmission rod 15, and the first transmission rod 15 is hinged with the upper side of the tail nozzle fitting plate 12, so as to facilitate the first servo motor 14 to drive the tail nozzle fitting plate 12 to rotate.

[0047] As another embodiment, the driving mechanism includes: a second servo motor 16, the second servo motor 16 is located above the combustion chamber 10, the movable end of the second servo motor 16 is hinged with a second transmission rod 17, and the second transmission rod 17 is hinged with the lower side of the lower wall adjustable plate 13, so as to facilitate the second servo motor 16 to drive the lower wall adjustable plate 13 to rotate.

[0048] The ratio of the outlet area of the single-sided expansion nozzle 11 to the outlet area of the combustion chamber 10 is 2 - 3.

[0049] The ratio of the inlet area of the single-sided expansion nozzle 11 to the outlet area of the combustion chamber 10 is 1.4226.

[0050] The initial expansion angle of the single-sided expansion nozzle 11 is 15° - 25°.

[0051] The tail nozzle fitting plate 12 and the lower wall adjustable plate 13 are the same rectangle. The long sides of the tail nozzle fitting plate 12 and the lower wall adjustable plate 13 are arranged along the airflow direction. The length of the tail nozzle fitting plate 12 and the lower wall adjustable plate 13 is equal to the height of the combustion chamber 10, and its width is equal to the width of the outlet of the combustion chamber 10.

[0052] When the Mach number is in the range of (0, 1.2], the tail nozzle fitting plate 12 rotates downward and the angle with the lower wall of the single-sided expansion nozzle 11 is 18°, and the lower wall adjustable plate 13 rotates upward and the angle with the lower wall of the single-sided expansion nozzle 11 is 16°; that is, when the Mach number is in the range of (0, 1.2], the ratio of the front-end opening area to the rear-end opening area of the tail nozzle fitting plate 12 and the lower wall adjustable plate 13 is 0.5 - 0.6.

[0053] When the Mach number is in the range of (1.2, 2], the tail nozzle fitting plate 12 rotates upward and the angle with the lower wall of the single-sided expansion nozzle 11 is 25°, and the lower wall adjustable plate 13 rotates upward and the angle with the lower wall of the single-sided expansion nozzle 11 is 16°; that is, when the Mach number is in the range of (1.2, 2], the ratio of the front-end opening area to the rear-end opening area of the tail nozzle fitting plate 12 and the lower wall adjustable plate 13 is 1.0 - 1.5.

[0054] When the Mach number > 2, the tail nozzle fitting plate 12 rotates downward and the angle with the lower wall surface of the single-sided expansion nozzle 11 is 25°, and the angle of the lower wall surface adjustable plate 13 with the horizontal plane is 0°; that is, when the Mach number > 2, the ratio of the front-end opening area to the rear-end opening area of the tail nozzle fitting plate 12 and the lower wall surface adjustable plate 13 is 2.0 - 3.0.

[0055] The present invention also discloses a method for reducing the drag of the tail nozzle in the ejector mode before the tail nozzle, including:

[0056] When the Mach number is (0, 1.2], drive the first servo motor 14 to drive the tail nozzle fitting plate 12 to rotate downward until the angle with the lower wall surface of the single-sided expansion nozzle 11 is 18°. At the same time, drive the second servo motor 16 to drive the lower wall surface adjustable plate 13 to rotate upward until the angle with the lower wall surface of the single-sided expansion nozzle 11 is 16°.

[0057] When the Mach number is (1.2, 2], drive the first servo motor 14 to drive the tail nozzle fitting plate 12 to rotate upward until the angle with the lower wall surface of the single-sided expansion nozzle 11 is 25°, and keep the angle of the lower wall surface adjustable plate 13 with the lower wall surface of the single-sided expansion nozzle 11 at 16°.

[0058] When the Mach number > 2, keep the angle of the tail nozzle fitting plate 12 with the lower wall surface of the single-sided expansion nozzle 11 at 25°, and drive the second servo motor 16 to drive the lower wall surface adjustable plate 13 to rotate downward until the angle with the lower wall surface of the single-sided expansion nozzle 11 is 0°.

[0059] In the state where the Mach number of the ejector mode is (0, 1.2], the tail nozzle fitting plate 12 rotates downward and the lower wall surface adjustable plate 13 rotates upward. At this time, the expansion ratio of the single-sided expansion nozzle 11 satisfies the expansion ratio in this flight state; in the state where the Mach number of the ejector mode is (1.2, 2], the tail nozzle fitting plate 12 rotates upward and the lower wall surface adjustable plate 13 remains unchanged to meet the increasing expansion ratio as the flight Mach number increases; in the scramjet supersonic combustion mode, as the flight Mach number increases, the tail nozzle fitting plate 12 remains unchanged, and the lower wall surface adjustable plate 13 rotates downward to maintain a horizontal state and the angle with the lower wall surface of the single-sided expansion nozzle 11 is 0° to expand the expansion ratio of the single-sided expansion nozzle 11 and make the flight performance reach the optimal. The following are the results obtained by simulation:

[0060] Table 1

[0061]

[0062] Figure 4 and Figure 5 are the Ma diagram and Pa diagram when the incoming flow Mach number is 0. At this time, the drag of the single-sided expansion nozzle 11 is only 20 N / m 2, there is almost no under-expanded resistance. From the Ma diagram, the flow velocity of the air flow ejected from the combustion chamber 10 continuously decreases towards the surroundings. From the pressure contour diagram, the pressure has expanded to 0.1 MPa when the air flow leaves the edges of the tail nozzle fitting plate 12 and the lower wall adjustable plate 13. Therefore, the single-sided expansion nozzle 11 has almost no under-expansion.

[0063] Figure 6 and Figure 7 are the Ma diagram and Pa diagram when the incoming flow Mach number is 1.6. At this time, the single-sided expansion nozzle 11 provides a large positive thrust of 4489 N / m 2 , and there is no under-expanded resistance. From the Mach number contour diagram, the Mach number of the air flow ejected from the single-sided expansion nozzle 11 can reach 2.4 Ma. From the pressure contour diagram, the air flow expands fully in the single-sided expansion nozzle 11, and there is no under-expansion.

[0064] Figure 8 and Figure 9 are the Ma diagram and Pa diagram when the incoming flow Mach number is 6. At this time, the single-sided expansion nozzle 11 provides a large positive thrust of 5493 N / m 2 . From the Mach number contour diagram, the Mach number of the air flow at the outlet of the single-sided expansion nozzle 11 is 3.5. From the pressure contour diagram, the air flow expands fully in the single-sided expansion nozzle 11, and the pressure at the outlet is close to one standard atmospheric pressure.

[0065] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A device located before the tail nozzle for reducing the drag of the tail nozzle in the ejection mode, characterized in that: The device is located between the combustion chamber (10) and the unilateral expansion nozzle (11); The device comprises: A tail nozzle interlocking plate (12), the front end of which is hinged to the rear end upper side wall of the combustion chamber (10), and the rear end of which is arranged close to the expansion surface of the inlet of the single-side expansion nozzle (11); A lower wall adjustable plate (13), the front end of which is hinged to the rear end lower side wall of the combustion chamber (10), and the rear end of which is arranged close to the lower wall of the inlet of the single-side expansion nozzle (11); The driving mechanism is used to drive the tail jet interlocking plate (12) and the lower wall adjustable plate (13) to rotate around the corresponding hinge point, thereby making the tail jet interlocking plate (12) and the lower wall adjustable plate (13) cooperate with each other and adapt to the incoming flow speed.

2. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1 is characterized in that: The driving mechanism comprises: The first servo motor (14) is located on the upper side of the combustion chamber (10), and a first transmission rod (15) is hinged at its movable end. The first transmission rod (15) is hinged to the upper side of the tail nozzle mosaic plate (12), thereby facilitating the first servo motor (14) to drive the tail nozzle mosaic plate (12) to rotate.

3. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: The driving mechanism comprises: The second servo motor (16) is located on the upper side of the combustion chamber (10), and a second transmission rod (17) is hinged at its movable end. The second transmission rod (17) is hinged to the lower side of the lower wall adjustable plate (13), thereby facilitating the second servo motor (16) to drive the lower wall adjustable plate (13) to rotate.

4. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: The ratio of the outlet area of ​​the unilateral expansion nozzle (11) to the outlet area of ​​the combustion chamber (10) is 2-3.

5. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: The initial expansion angle of the unilateral expansion nozzle (11) is 15°-25°.

6. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: The tail jet interlocking plate (12) and the lower wall adjustable plate (13) are in the same rectangular shape, the long sides of the tail jet interlocking plate (12) and the lower wall adjustable plate (13) are arranged along the direction of the airflow, the length of the tail jet interlocking plate (12) and the lower wall adjustable plate (13) is equal to the height of the combustion chamber (10), and the width thereof is equal to the width of the outlet of the combustion chamber (10).

7. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: When the Mach number is (0, 1.2], the tail jet interlocking plate (12) rotates downward and forms an angle of 18° with the lower wall of the single-sided expansion nozzle (11), and the lower wall adjustable plate (13) rotates upward and forms an angle of 16° with the lower wall of the single-sided expansion nozzle (11).

8. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: When the Mach number is (1.2, 2], the tail nozzle interlocking plate (12) rotates upward and the angle between it and the lower wall of the single-sided expansion nozzle (11) is 25°, and the lower wall adjustable plate (13) rotates upward and the angle between it and the lower wall of the single-sided expansion nozzle (11) is 16°.

9. The device for reducing the drag of the tail nozzle in the ejection mode located before the tail nozzle according to claim 1, characterized in that: When the Mach number is greater than 2, the tail nozzle interlocking plate (12) rotates upward and forms an angle of 25° with the lower wall of the single-sided expansion nozzle (11), and the lower wall adjustable plate (13) rotates downward and forms an angle of 0° with the lower wall of the single-sided expansion nozzle (11).

10. A method for reducing the drag of a tail nozzle in an ejection mode located before the tail nozzle, characterized in that: include: When the Mach number is (0, 1.2], the first servo motor (14) is driven to drive the tail nozzle engaging plate (12) to rotate downward until the angle between the tail nozzle engaging plate (12) and the lower wall surface of the single-sided expansion nozzle (11) is 18°, and at the same time, the second servo motor (16) is driven to drive the lower wall adjustable plate (13) to rotate upward until the angle between the tail nozzle engaging plate (12) and the lower wall surface of the single-sided expansion nozzle (11) is 16°; When the Mach number is (1.2, 2], the first servo motor (14) is driven to drive the tail nozzle engaging plate (12) to rotate upward until the included angle with the lower wall surface of the single-sided expansion nozzle (11) is 25°, and the included angle between the lower wall surface adjustable plate (13) and the lower wall surface of the single-sided expansion nozzle (11) is maintained at 16°; When the Mach number is greater than 2, the included angle between the tail nozzle interlocking plate (12) and the lower wall surface of the single-sided expansion nozzle (11) is maintained at 25°, and the second servo motor (16) is driven to drive the lower wall adjustable plate (13) to rotate downward until the included angle between the tail nozzle interlocking plate (12) and the lower wall surface of the single-sided expansion nozzle (11) is 0°.

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