Exhaust nozzle and aircraft

Abstract

Embodiments of this specification provide an exhaust nozzle and an aircraft. The exhaust nozzle may include: a ramjet airflow channel corresponding to a ramjet engine, the ramjet airflow channel including a convergent section and a divergent section; a cooling channel including a cooling section, a jet section, and a valve, the cooling section being provided with a first outlet, the jet section being provided with a second outlet, and the valve being used to control the flow of cooling air from the cooling section into the jet section. When the ramjet engine is operating, the valve is closed, and cooling air from the cooling section enters the convergent section through the first outlet. When the ramjet engine is not operating, the valve is open, and cooling air from the cooling section enters the jet section through the valve, and cooling air from the jet section enters the divergent section through the second outlet. Embodiments of this specification can improve the aerodynamic performance of the exhaust nozzle.

Description

Technical Field

[0001] The embodiments of this specification relate to the field of aerospace technology, and in particular to an exhaust nozzle and an aircraft. Background Art

[0002] The flight speed range of hypersonic aircraft spans subsonic, transonic, supersonic and hypersonic ranges.

[0003] In related technologies, turbine engines and ramjets each operate only within a narrow flight speed range. To achieve wide-speed flight, turbine engines and ramjets can be combined to form a turbine-based combined cycle engine. The exhaust nozzle of a turbine-based combined cycle engine can be a combined exhaust nozzle. The combined exhaust nozzle includes a ramjet airflow channel corresponding to the ramjet and a turbine airflow channel corresponding to the turbine engine.

[0004] The inventors have discovered that the above-mentioned related technologies have at least the following technical problems.

[0005] During low-speed flight, the turbine engine operates while the ramjet does not, but the ramjet channel remains open. This results in a low inlet pressure at the ramjet channel, causing the outlet pressure to fall below atmospheric pressure, leading to overexpansion. This overexpansion can degrade the aerodynamic performance of the exhaust nozzle, for example, reducing its thrust. Summary of the Invention

[0006] The purpose of the embodiments of this specification is to provide an exhaust nozzle and an aircraft to improve the aerodynamic performance of the exhaust nozzle.

[0007] The technical solutions of the embodiments of this specification are as follows.

[0008] In a first aspect of the embodiments of this specification, an exhaust nozzle is provided, comprising:

[0009] A ramjet airflow channel corresponding to a ramjet engine, wherein the ramjet airflow channel includes a convergent section and a divergent section;

[0010] A cooling channel, the cooling channel comprising a cooling section, a jet section and a valve, the cooling section being provided with a first outlet, the jet section being provided with a second outlet, and the valve being used to control the cooling airflow in the cooling section to enter the jet section;

[0011] When the ramjet engine is working, the valve is in a closed state, and the cooling airflow in the cooling section enters the convergent section through the first outlet. When the ramjet engine is not working, the valve is in an open state, and the cooling airflow in the cooling section enters the jet section through the valve, and the cooling airflow in the jet section enters the expansion section through the second outlet.

[0012] According to a second aspect of the embodiments of this specification, an aircraft is provided, comprising:

[0013] A turbine-based combined cycle engine, wherein the turbine-based combined cycle engine comprises a ramjet engine and a turbine engine;

[0014] an exhaust nozzle, the exhaust nozzle comprising a ramjet airflow channel corresponding to the ramjet engine, a turbine airflow channel corresponding to the turbine engine, and a cooling channel; wherein the ramjet airflow channel comprises a convergent section and a divergent section, and the cooling channel comprises a cooling section, a jet section, and a valve; the cooling section is provided with a first outlet, the jet section is provided with a second outlet, and the valve is used to control the cooling airflow in the cooling section to enter the jet section;

[0015] When the ramjet engine is working, the valve is in a closed state, and the cooling airflow in the cooling section enters the convergent section through the first outlet. When the ramjet engine is not working, the valve is in an open state, and the cooling airflow in the cooling section enters the jet section through the valve, and the cooling airflow in the jet section enters the expansion section through the second outlet.

[0016] It can be seen from the technical solutions provided in the above embodiments of this specification that, in the embodiments of this specification, the cooling airflow in the cooling section is used to introduce a jet into the over-expanded ramjet airflow channel through the second outlet, inducing flow separation at the jet position, thereby regulating the separation area to a position that causes less damage to the aerodynamic performance. In addition, since the cooling airflow of the jet section is introduced by the cooling section, the integrated design of the jet section and the cooling section is facilitated. As a result, the cooling channel can achieve the cooling function under high-speed conditions, and can also have the function of regulating the position of the separation area under low-speed conditions. In addition, the embodiments of this specification can use the cooling channel to improve the low-speed aerodynamic performance of the ramjet airflow channel in the exhaust nozzle. And there is no need to introduce complex mechanical structures such as additional actuating devices, nor is there a need to design a separate air bleed channel, so the aerodynamic performance of the exhaust nozzle can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 This is a schematic structural diagram of an exhaust nozzle according to an embodiment of this specification;

[0019] Figure 2 This is a schematic structural diagram of an exhaust nozzle according to an embodiment of this specification;

[0020] Figure 3 This is a schematic diagram of the position of the separation area in the ram air flow channel after the jet is introduced into the embodiment of this specification;

[0021] Figure 4 This is a schematic diagram of the pressure in the ram air flow channel after the jet is introduced in the embodiment of this specification.

[0022] Description of reference numerals:

[0023] 1. Fuselage; 2. Turbine airflow channel; 3. Ram airflow channel; 31. Converging section; 32. Diverging section; 33. Throat; 4. Inlet adjustment plate; 5. Adjustment plate of turbine airflow channel; 6. Lower belly plate; 7. Expansion surface; 8. Cooling channel; 81. Cooling section; 811. First outlet; 82. Jet section; 821. Second outlet; 83. Valve; 17. Oblique shock wave; 18. Bow shock wave; 19. Primary vortex; 20. Secondary vortex; 21. Separation area; 22. Wall pressure distribution curve of lower belly plate 6 after jet introduction; 23. Reference line of external atmospheric pressure; 24. Wall pressure distribution curve of lower belly plate 6 when no jet is introduced. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the embodiments described are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts should fall within the scope of protection of this specification.

[0025] Flow separation, also known as boundary layer separation, occurs when a fluid, under the combined effects of wall friction and adverse pressure differential, slows down until it stops or even reverses, forcing the main flow away from the wall. Flow separation significantly impacts flow resistance and flow losses, making it one of the most common flow phenomena encountered by engineers.

[0026] The exhaust nozzle of the aircraft can adopt the form of a single expansion ramp nozzle (SERN). In the form of a single expansion ramp nozzle, the length of the expansion surface is greater than the lower belly plate of the aircraft. By adopting the form of a single expansion ramp nozzle, a higher expansion ratio can be obtained. Under the low-speed operating conditions of the aircraft, the turbine engine is working and the ramjet engine is not working, but the ramjet airflow channel remains in a flow state. In this way, the inlet pressure of the ramjet airflow channel is low, so that the pressure at the outlet of the ramjet airflow channel is lower than the external atmospheric pressure, resulting in an over-expansion phenomenon. The over-expansion phenomenon causes flow separation in the ramjet airflow channel, and the area where flow separation occurs (hereinafter referred to as the separation area) is usually located on the expansion surface side of the aircraft. On the one hand, this will reduce the thrust of the exhaust nozzle, and on the other hand, it will produce an undesirable nose-up torque, which is not conducive to the control of the aircraft.

[0027] In related technologies, the aerodynamic performance of the exhaust nozzle is often improved based on the angle of eliminating the separation area. For example, the aerodynamic performance of the exhaust nozzle is improved by using methods such as an adjustable lower belly plate, external combustion, and injection. However, all of the above methods have certain problems. The adjustable lower belly plate requires the introduction of an additional action device, which increases the weight of the aircraft, and after the lower belly plate is deflected, a separation area will be formed on the rear body of the aircraft, increasing the outflow resistance. The external combustion method increases fuel consumption and is difficult to control. The injection method requires the additional design of an air intake system, and a large amount of air is drawn from the air inlet, engine, etc., which reduces the engine's operating efficiency.

[0028] The inventors discovered that flow separation within the ramjet airflow channel is difficult to eliminate under low-speed aircraft conditions. However, the location of the separation zone can be controlled. Different locations of the separation zone have varying degrees of detriment to the aerodynamic performance of the exhaust nozzle. If the separation zone can be adjusted to a position that minimizes the detriment, the effects of flow separation can be reduced, improving the aerodynamic performance of the exhaust nozzle.

[0029] See also Figure 1 and Figure 2 The embodiments of this specification provide an exhaust nozzle.

[0030] The exhaust nozzle may be provided on an aircraft. The aircraft may include a cruise missile, an airplane, a spacecraft, or the like. The aircraft may include a hypersonic aircraft. The flight speed range of a hypersonic aircraft spans the subsonic, transonic, supersonic, and hypersonic ranges. The aircraft may include a turbine-based combined cycle engine. The turbine-based combined cycle engine may include a turbine engine and a ramjet engine. The turbine engine and the ramjet engine are placed side by side in an upper and lower arrangement. When the aircraft is flying at a low speed, the turbine engine operates and the ramjet engine does not operate. When the aircraft is flying at a high speed, the turbine engine does not operate and the ramjet engine operates. In this way, the turbine-based combined cycle engine enables the aircraft to achieve flight over a wide speed range.

[0031] The exhaust nozzle may include the exhaust nozzle of a turbine-based combined cycle engine. Considering the relatively low atmospheric pressure at cruising altitude, the exhaust nozzle may be a single-slope expansion nozzle. In a single-slope expansion nozzle, the expansion surface 7 is longer than the lower belly 6 of the aircraft. This single-slope expansion nozzle achieves a higher expansion ratio.

[0032] In some embodiments, the exhaust nozzle may include a ramjet airflow channel 3. The ramjet airflow channel 3 corresponds to a ramjet engine and can be used as an exhaust channel of the ramjet engine. The ramjet airflow channel 3 may be in a convergent-divergent form. The cross-sectional area of the ramjet airflow channel 3 first converges and then expands. The ramjet airflow channel 3 may include a convergent section 31 and an expander section 32. The convergent section 31 is used to accelerate the main airflow in the ramjet airflow channel 3. By accelerating, the speed of the main airflow can reach a set speed, for example, the speed of the main airflow reaches the speed of sound. The expander section 32 is used to further accelerate and discharge the accelerated main airflow. The convergent section 31 and the expander section 32 may be separated by a throat 33. Along the flow direction of the main airflow in the ramjet airflow channel 3, the convergent section 31 is located in front of the expander section 32. By adopting a convergent-divergent form, the exhaust nozzle can generate good thrust.

[0033] In some embodiments, when the ramjet engine is operating, the temperature in the ramjet airflow channel 3 is relatively high. To reduce the temperature, the exhaust nozzle may further include a cooling channel 8. The portion of the cooling channel 8 located below the convergent section 31 may be referred to as a cooling section 81. The cooling section 81 is used to cool the convergent section 31. In practical applications, a first outlet 811 may be provided on the cooling section 81. The cooling channel 8 may introduce cooling airflow from a cold end (e.g., a turbine engine compressor, an air inlet, etc.). The cooling airflow in the cooling section 81 may enter the convergent section 31 through the first outlet 811. This achieves cooling of the main airflow in the convergent section 31.

[0034] The number of the first outlets 811 can be one or more. The first outlets 811 can be holes or slits. The first outlets 811 can pass through the wall of the cooling section 81 and communicate with the convergent section 31 to facilitate the cooling airflow in the cooling section 81 to enter the convergent section 31.

[0035] In some embodiments, considering that when a jet is introduced into the air flow channel, the main air flow in the air flow channel will be obstructed, flow separation will occur behind the jet position. And flow separation can be induced by a small flow jet. To this end, the cooling section 81 can be extended. The extended portion can pass through the throat 33 to the expansion section 32. The extended portion can be called a jet section 82. The jet section 82 can be located below the expansion section 32, and is used to introduce a small flow jet into the expansion section 32 to induce flow separation in the expansion section 32. In actual applications, a second outlet 821 can be provided on the jet section 82. The cooling airflow in the jet section 82 can enter the expansion section 32 through the second outlet 821. The cooling airflow ejected from the second outlet 821 can form a jet. Flow separation will occur behind the jet position of the expansion section 32. This allows the position of the separation zone within the ram flow channel 3 to be regulated, positioning the separation zone to a location that minimizes the impact on thrust and torque, reducing the damage to the exhaust nozzle's aerodynamic performance caused by flow separation due to overexpansion and improving the nozzle's aerodynamic performance. Specifically, the cooling airflow ejected from the second outlet 821 can form a jet, adjusting the position of the separation zone within the ram flow channel 3 to the lower belly plate 6 of the aircraft. Compared to a separation zone positioned on the expansion surface 7, a separation zone positioned on the lower belly plate 6 generates a smaller nose-up moment, facilitating aircraft trim. Furthermore, a separation zone positioned on the lower belly plate 6 also minimizes the negative impact on the exhaust nozzle's thrust performance.

[0036] The cooling section 81 can be extended to a position not far from the throat 33, so that the distance between the second outlet 821 and the throat 33 is within a set range. This allows the induced separation region to be closer to the throat 33, resulting in a higher wall pressure within the separation region, which has a smaller negative impact on the exhaust nozzle thrust performance and improves the exhaust nozzle's aerodynamic performance.

[0037] The second outlet 821 can be located at the end of the jet section 82 and communicate with the expansion section 32, facilitating the cooling airflow within the jet section 82 into the expansion section 32. The second outlet 821 can be a hole or a slit. The direction of the second outlet 821 can be perpendicular to the direction of the main airflow within the expansion section 32. The second outlet 821 can be in a converging configuration, such that the jet ejected from the second outlet 821 can reach a set velocity. The set velocity can include the speed of sound, a velocity less than the speed of sound, or the like.

[0038] In some specific examples, the jet section 82 can start from the throat 33 of the exhaust nozzle and end at a set position of the lower web 6. The set position can be 20% to 50% of the length of the lower web 6. A second outlet 821 is provided at the end of the jet section 82. The size of the second outlet 821 can be a set size. The second outlet 821 can be a slit, a discrete hole, multiple rows of slits, etc. The size of the second outlet 821 can be the width of the slit or the diameter of the hole, etc. The set size can be 1% to 2% of the length of the lower web 6. The pressure of the cooling airflow at the second outlet 821 can be adjusted by a pressure regulating system at the cold end. Through the pressure regulating system, the pressure at the second outlet 821 when the jet is introduced can be greater than the pressure when the jet is not introduced. For example, through the pressure regulating system, the ratio of the pressure of the cooling airflow at the second outlet 821 to the external atmospheric pressure can be 4:1.

[0039] In some embodiments, the cooling channel 8 may further include a valve 83. The valve 83 may be located below the throat 33 formed by the converging section 31 and the diverging section 32. The valve 83 connects the cooling section 81 with the jet section 82, thereby controlling the flow of cooling air from the cooling section 81 into the jet section 82. During high-speed flight, the turbine engine is inoperative and the ramjet is in operation. The valve 83 is closed. The cooling air from the cooling section 81 can enter the converging section 31 through the first outlet 811, thereby cooling the main airflow within the converging section 31. During low-speed flight, the turbine engine is inoperative and the ramjet is inoperative. The valve 83 is open. During this time, the ramjet channel 3 remains open. As the main airflow continuously expands within the ramjet channel 3, the pressure in the converging section 31 is greater than that in the diverging section 32, while the pressures in the cooling section 81 and the jet section 82 are close. Due to the pressure differential, the majority of the cooling air from the cooling section 81 enters the jet section 82 through the valve 83. The cooling airflow in the jet section 82 can enter the expansion section 32 through the second outlet 821 , thereby inducing flow separation in the expansion section 32 .

[0040] In some embodiments, the exhaust nozzle may further include a turbine airflow channel 2. The turbine airflow channel 2 corresponds to the turbine engine and can be used as the exhaust channel of the turbine engine. The turbine airflow channel 2 may be in a convergent-divergent form. By adopting a convergent-divergent form, the exhaust nozzle can generate good thrust. An adjustment plate 5 may be provided at the end of the turbine airflow channel 2. The adjustment plate 5 can move between an open position and a closed position. When the turbine engine is working, the adjustment plate 5 can be deflected to the open position to open the turbine airflow channel 2. When the turbine engine is not working, the adjustment plate 5 can be deflected to the closed position to close the turbine airflow channel 2. In the closed position, the adjustment plate 5 can form an expansion surface 7 with the fuselage 1 of the aircraft. The length of the expansion surface 7 is greater than the lower belly plate 6 of the aircraft. Thus, a single-slope expansion nozzle is formed.

[0041] It is worth noting that the air inlet of the turbine airflow channel 2 may also be provided with an adjustment plate 4. The adjustment plate 4 can move between an open position and a closed position. The adjustment plate 4 cooperates with the adjustment plate 5 to realize the opening or closing of the turbine airflow channel 2. Specifically, under the low-speed operating condition of the aircraft, the turbine engine is working, and the adjustment plate 4 and the adjustment plate 5 can be deflected to the open position to open the turbine airflow channel 2. Under the high-speed operating condition of the aircraft, the turbine engine is not working, and the adjustment plate 4 and the adjustment plate 5 can be deflected to the closed position to close the turbine airflow channel 2. Figure 1 In the embodiment, the regulating plate 4 and the regulating plate 5 are located in the open position.

[0042] It is worth noting that, in addition to the cooling section 81 located below the convergent section 31 and the jet section 82 located below the divergent section 32, the cooling channel 8 may also include other sections. For example, the cooling channel 8 may also include a section located above the upper wall of the ram airflow channel 3. This section may also be provided with an outlet. The cooling airflow in the cooling channel 8 may also enter the ram airflow channel 3 through this outlet to cool the main airflow in the ram airflow channel 3.

[0043] It is worth noting that, in addition to the cooling channel 8 for cooling the ram airflow channel 3, the exhaust nozzle may also include other cooling channels. For example, the exhaust nozzle may also include a cooling channel for cooling the turbine airflow channel 2. This cooling channel may be located above the upper wall of the ram airflow channel 3 and below the turbine airflow channel 2. This cooling channel may also draw cooling air from a cold end (e.g., a turbine engine compressor or air inlet).

[0044] It is worth noting that the ram airflow channel 3 can be located below the turbine airflow channel 2. The ram airflow channel 3 and the turbine airflow channel 2 can be separated by a partition plate and are not connected to each other. The cooling channel 8 can be connected to the ram airflow channel 3 through the first outlet 811 and the second outlet 821.

[0045] The exhaust nozzle of the embodiment of this specification utilizes the cooling airflow in the cooling section to introduce a jet into the over-expanded ramjet airflow channel through the second outlet, inducing flow separation at the jet position, thereby regulating the separation area to a position that is less detrimental to the aerodynamic performance. In addition, since the cooling airflow of the jet section is introduced by the cooling section, the integrated design of the jet section and the cooling section is facilitated. As a result, the cooling channel can achieve a cooling function under high-speed conditions, and can also have the function of regulating the position of the separation area under low-speed conditions. In addition, the jet section 82 is obtained by extending the cooling section 81. In this way, the existing cooling channel 8 can be used to improve the low-speed aerodynamic performance of the ramjet airflow channel 3 in the exhaust nozzle. And there is no need to introduce complex mechanical structures such as additional actuating devices, nor is there a need to design a separate air bleed channel, so the aerodynamic performance of the exhaust nozzle can be improved.

[0046] For some specific examples, see Figure 3 and Figure 4 . The jet section 82 is obtained by extending the cooling section 81. The second outlet 821 of the jet section 82 is used to introduce the jet. The introduction of the jet hinders the main airflow in the expansion section 32, and the separation area 21 is introduced behind the second outlet 821. When the ram airflow channel 3 is in an over-expanded state, the separation area 21 can extend to the trailing edge of the exhaust nozzle. The pressure at the location of the separation area 21 is basically the same as the external atmospheric pressure, and is greater than the pressure at this location when the jet is not introduced. In addition, a separation area can also be introduced in front of the second outlet 821, and a primary vortex 19 and a secondary vortex 20 can be formed in the separation area. Due to the obstruction of the primary vortex 19 and the secondary vortex 20, an oblique shock wave 17 can be formed. At the same time, due to the obstruction of the jet itself, a bow shock wave 18 will also be formed. The oblique shock wave 17 and the bow shock wave 18 propagate to the expansion surface 7, which will increase the pressure on the expansion surface 7. The pressure change reduces the thrust loss caused by flow separation in the overexpanded exhaust nozzle on the one hand, and reduces the nose-up moment on the other hand, thereby facilitating the control of the aircraft.

[0047] exist Figure 4 In the figure, the origin is the throat 33, the vertical axis represents pressure, and the horizontal axis represents distance. The horizontal axis is axial to the aircraft and points toward the tail of the aircraft. Reference numeral 22 represents the pressure distribution curve on the wall of the lower web 6 after the jet is introduced, reference numeral 23 represents the reference line for the ambient atmospheric pressure, and reference numeral 24 represents the pressure distribution curve on the wall of the lower web 6 without the jet.

[0048] In some specific examples, before the cooling section 81 is extended (i.e., before the jet is introduced into the expansion section 32), the integrated axial thrust coefficient of the exhaust nozzle can be expressed as Among them, F x represents the actual thrust of the ram airflow channel 3, F id represents the ideal thrust of the ram airflow channel 3, Before extending the cooling section 81 (i.e., before introducing the jet into the expansion section 32), the thrust vector angle of the exhaust nozzle can be expressed as Among them, F y represents the component of the vector thrust in the y direction, F x represents the component of the vector thrust in the x-direction. For example, the x-direction may be the flight direction of the aircraft, and the y-direction may be a direction perpendicular to the flight direction and pointing upward.

[0049] After extending the cooling section 81 (i.e., after introducing the jet in the expansion section 32), the comprehensive axial thrust coefficient of the exhaust nozzle can be expressed as Among them, F x,inj represents the actual thrust of the ram airflow channel 3, F id represents the ideal thrust of the ram airflow channel 3 before the jet is introduced, F x,id represents the ideal thrust of the ramjet flow channel 3 after the jet is introduced. After the cooling section 81 is extended (i.e., after the jet is introduced into the expansion section 32), the thrust vector angle of the exhaust nozzle can be expressed as Among them, F y,inj It represents the component of the vector thrust in the y direction after the jet is introduced, F x represents the component of the vector thrust in the x-direction after the jet is introduced. For example, the x-direction may be the flight direction of the aircraft, and the y-direction may be a direction perpendicular to the flight direction and pointing upward.

[0050] Through analysis and comparison, after the cooling section 81 is extended (i.e., after the jet is introduced into the expansion section 32), the comprehensive axial thrust coefficient of the exhaust nozzle is improved (i.e., C fx,inj Greater than C fx ), while the thrust vector angle is reduced (i.e., θ f,inj Less than θ f This improves the aerodynamic performance of the exhaust nozzle. For example, when the pressure drop ratio of the ramjet airflow channel 3 is within the range of 1.8 to 4.5, the introduction of the jet can increase the overall axial thrust coefficient by an average of 7.3% and reduce the thrust vector angle by 34.8%.

[0051] The embodiments of this specification also provide an aircraft accordingly.

[0052] The aircraft may include a cruise missile, an airplane, a spacecraft, etc. The aircraft may include a hypersonic aircraft. The flight speed range of a hypersonic aircraft spans the subsonic, transonic, supersonic and hypersonic ranges.

[0053] The aircraft may include a turbine-based combined cycle engine. The turbine-based combined cycle engine may include a turbine engine and a ramjet. The turbine engine and the ramjet are placed side by side, one above the other. During low-speed flight, the turbine engine operates, while the ramjet does not. During high-speed flight, the turbine engine does not operate, while the ramjet operates. This turbine-based combined cycle engine enables the aircraft to achieve flight over a wide speed range.

[0054] The aircraft may include an exhaust nozzle of a turbine-based combined cycle engine. The exhaust nozzle may include a ram airflow channel 3. The ram airflow channel 3 may include a convergent section 31 and a divergent section 32. The convergent section 31 is used to accelerate the main airflow within the ram airflow channel 3, and the divergent section 32 is used to further accelerate and discharge the accelerated main airflow. The convergent section 31 and the divergent section 32 are separated by a throat 33. Along the flow direction of the main airflow within the ram airflow channel 3, the convergent section 31 is located in front of the divergent section 32.

[0055] The exhaust nozzle may further include a cooling channel 8. The cooling channel 8 may include a cooling section 81. The cooling section 81 may be located below the converging section 31 and is used to cool the converging section 31. The cooling section 81 may be provided with one or more first outlets 811. The cooling section 81 may introduce cooling airflow from a cold end (e.g., a turbine engine compressor, an air inlet, etc.). The cooling airflow within the cooling section 81 may enter the converging section 31 through the first outlet 811, thereby cooling the main airflow within the converging section 31.

[0056] The cooling channel 8 may also include a jet section 82. The jet section 82 is located below the expansion section 32 and is used to introduce a jet with a small flow rate into the expansion section 32. Flow separation will occur behind the jet position of the expansion section 32, thereby adjusting the separation area of the ramjet airflow channel 3 to a position that causes less damage to the thrust and torque. A second outlet 821 may be provided on the jet section 82. The cooling airflow in the jet section 82 may enter the expansion section 32 through the second outlet 821. The second outlet 821 may be used as a jet outlet. The jet ejected from the jet outlet may induce flow separation in the expansion section 32. In this way, by regulating the position of the separation area in the ramjet airflow channel 3, the damage to the aerodynamic performance of the exhaust nozzle caused by the flow separation caused by over-expansion may be reduced.

[0057] The cooling channel 8 may further include a valve 83. The valve 83 may be located below the throat 33. The valve 83 is used to connect the cooling section 81 and the jet section 82, thereby controlling the cooling airflow in the cooling section 81 to enter the jet section 82. When the aircraft is flying at high speed, the turbine engine is not operating and the ramjet is operating. The valve 83 is in a closed state. The cooling airflow in the cooling section 81 can enter the convergent section 31 through the first outlet 811. This achieves cooling of the main airflow in the convergent section 31. When the aircraft is flying at low speed, the turbine engine is operating and the ramjet is not operating. The valve 83 is in an open state. The cooling airflow in the cooling section 81 can enter the jet section 82 through the valve 83. The cooling airflow in the jet section 82 can enter the divergent section 32 through the second outlet 821. This induces flow separation in the divergent section 32, and enables the separation area to be regulated to a position that minimizes damage to aerodynamic performance.

[0058] The exhaust nozzle may further include a turbine airflow channel 2. The turbine airflow channel 2 corresponds to the turbine engine and can be used as the exhaust channel of the turbine engine. An adjustment plate 5 may be provided at the end of the turbine airflow channel 2. The adjustment plate 5 is movable between an open position and a closed position. When the turbine engine is working, the adjustment plate 5 may be deflected to the open position to open the turbine airflow channel 2. When the turbine engine is not working, the adjustment plate 5 may be deflected to the closed position to close the turbine airflow channel 2. In the closed position, the adjustment plate 55 may form an expansion surface 7 with the fuselage 1 of the aircraft. The length of the expansion surface 7 is greater than the lower belly plate 6 of the aircraft. Thus, a single-slope expansion nozzle is formed.

[0059] Those skilled in the art will understand that the descriptions of the various embodiments have different focuses, and for portions not described in detail in one embodiment, reference can be made to the relevant descriptions of other embodiments. Furthermore, it is also understood that after reading this specification, those skilled in the art may, without inventive effort, conceive of any combination of some or all of the embodiments listed in this specification, and such combinations are also within the scope of disclosure and protection of this specification.

[0060] Although the present specification has been described with reference to the embodiments, those skilled in the art will appreciate that there are many modifications and variations to the present specification, and it is intended that the appended claims encompass such modifications and variations without departing from the spirit of the present specification.

Claims

1. An exhaust nozzle, characterized in that: include: A ramjet airflow channel corresponding to a ramjet engine, wherein the ramjet airflow channel includes a convergent section and a divergent section; A cooling channel, the cooling channel comprising a cooling section, a jet section and a valve, the cooling section being provided with a first outlet, the jet section being provided with a second outlet, and the valve being used to control the cooling airflow in the cooling section to enter the jet section; When the ramjet engine is working, the valve is in a closed state, and the cooling airflow in the cooling section enters the convergent section through the first outlet. When the ramjet engine is not working, the valve is in an open state, and the cooling airflow in the cooling section enters the jet section through the valve, and the cooling airflow in the jet section enters the expansion section through the second outlet.

2. The exhaust nozzle according to claim 1, characterized in that: When the ramjet engine is not working, the ramjet airflow channel remains in a flowing state.

3. The exhaust nozzle according to claim 1, characterized in that The cooling section is located below the convergent section, the jet section is located below the divergent section, and the valve is located below the throat formed by the convergent section and the divergent section.

4. The exhaust nozzle according to claim 1, characterized in that Also includes: Corresponding to the turbine air flow channel of the turbine engine, the ram air flow channel is located below the turbine air flow channel.

5. The exhaust nozzle according to claim 4, characterized in that: An adjustment plate is provided at the end of the turbine airflow channel, and the adjustment plate can move between an open position and a closed position. The open position is used to open the turbine airflow channel when the turbine engine is working, and the closed position is used to close the turbine airflow channel when the turbine engine is not working.

6. The exhaust nozzle according to claim 5, characterized in that: In the closed position, the adjustment plate and the fuselage of the aircraft form an expansion surface, and the length of the expansion surface is greater than the lower belly plate of the aircraft.

7. The exhaust nozzle according to claim 1, characterized in that The second outlet is opened at the end of the jet section and communicates with the expansion section.

8. The exhaust nozzle according to claim 1 or 7, characterized in that: The second outlet is a convergent outlet, the direction of the second outlet is perpendicular to the flow direction of the main airflow in the expansion section, and the second outlet is a slit or a hole.

9. The exhaust nozzle according to claim 1 or 5, characterized in that: The first outlet passes through the wall of the cooling section and communicates with the convergent section. There are multiple first outlets, and the first outlets are slits or holes.

10. An aircraft, characterized in that: include: A turbine-based combined cycle engine, wherein the turbine-based combined cycle engine comprises a ramjet engine and a turbine engine; an exhaust nozzle, the exhaust nozzle comprising a ramjet airflow channel corresponding to the ramjet engine, a turbine airflow channel corresponding to the turbine engine, and a cooling channel; wherein the ramjet airflow channel comprises a convergent section and a divergent section, and the cooling channel comprises a cooling section, a jet section, and a valve; the cooling section is provided with a first outlet, the jet section is provided with a second outlet, and the valve is used to control the cooling airflow in the cooling section to enter the jet section; When the ramjet engine is working, the valve is in a closed state, and the cooling airflow in the cooling section enters the convergent section through the first outlet. When the ramjet engine is not working, the valve is in an open state, and the cooling airflow in the cooling section enters the jet section through the valve, and the cooling airflow in the jet section enters the expansion section through the second outlet.

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