Adjustable spray pipe suitable for high-frequency time-varying flow field of rotary detonation combined engine

Abstract

The invention discloses an adjustable spray pipe suitable for a high-frequency time-varying flow field of a rotary detonation combined engine, and relates to the field of combined power engines. The spray pipe is composed of a spray pipe inner cone, a spray pipe outer cover, a spray pipe inner cylinder composed of a movable piece and a fixed piece, and an electric push rod. The structure is characterized in that an outer culvert flow channel is designed according to an outlet flow field of the rotary detonation engine and is matched with an annular rotary detonation engine combustion chamber, and high thrust is ensured. The spray pipe inner barrel movable piece serves as a movable plug cone of the plug type spray pipe and slides on the spray pipe inner barrel fixed piece through traction of the electric push rod, and the throat area of the outer culvert and the throat area of the inner culvert are adjusted. According to the design, the engine is allowed to use the inner culvert flow channel to exhaust in a low-altitude low-Mach-number turbine mode and use the outer culvert flow channel to exhaust in a high-altitude high-Mach-number rotating detonation stamping mode. By adjusting the elongation of the electric push rod, the pressure change of the working environment of the engine is matched, the work of the spray pipe is optimized, and the heat-work conversion efficiency of the rotary detonation stamping combined engine in a wide speed domain range is improved.

Description

Technical Field

[0001] The invention relates to the field of combined power engines, in particular to an adjustable nozzle adapted to a high-frequency time-varying flow field of a rotating detonation combined engine. Background Art

[0002] Rotating detonation is a new type of combustion with advantages such as fast heat release rate and self-pressurization. Using a rotating detonation ramjet engine instead of a conventional ramjet engine can further broaden the speed range of the combined engine. The turbine engine mode is used at subsonic speed, and it transitions to the rotating detonation ramjet mode at supersonic speed. The outlet flow field of the rotating detonation combustion chamber is a typical high-frequency time-varying flow field, which requires that the nozzle used for the rotating detonation combustion chamber must be specially designed. Studies have shown that the plug nozzle performs better on the rotating detonation engine. Its annular feature can well connect the annular shape of the rotating detonation combustion chamber, and make the ejected airflow uniform, with better performance. However, the nozzle of the currently designed turbine-based ramjet combined engine is often an integrated design, and is often a two-dimensional design, that is, the nozzle outlet is designed to be square. If it is used for a rotating detonation ramjet engine, its shape is not suitable for the annular rotating detonation combustion chamber, and a transition section needs to be designed, which increases additional flow losses. For a turbine-based rotating detonation ramjet combination engine, it is necessary to design a nozzle that ensures good performance in both turbine and rotating detonation ramjet operating modes.

[0003] Due to the high-frequency time-varying flow field characteristics of rotating detonation, it is necessary to design an adjustable nozzle. The adjustment of the inner duct can ensure good performance of the engine in the turbine mode, while the adjustment of the outer duct can widen the working range of the rotating detonation ramjet mode, and the aircraft can further widen its working envelope. Summary of the invention

[0004] The purpose of the present invention is to provide an adjustable nozzle that adapts to the high-frequency time-varying flow field of a rotating detonation combination engine. Through the separate exhaust of the inner and outer ducts and the adjustability of the throat area, the separate exhaust of the inner and outer ducts of the combination engine can be realized, and the outer duct flow channel can be ensured to be an annular adjustable plug nozzle structure, which is well adapted to the annular rotating detonation engine, thereby ensuring the excellent performance of the aircraft in the rotating detonation ramjet mode, and the inner and outer duct throat areas can be adjusted according to the flight conditions to ensure the matching of the engine flow channels, thereby realizing efficient and stable operation of the combination engine in a wide speed range of flight.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] An adjustable nozzle adapted to the high-frequency time-varying flow field of a rotating detonation combination engine comprises a nozzle inner cone, a nozzle inner barrel, a nozzle outer cover and an electric push rod; the nozzle inner barrel comprises a nozzle inner barrel fixing part and a nozzle inner barrel movable part, and the two parts can slide relative to each other. The two ends of the electric push rod are respectively connected to the nozzle inner barrel fixed part and the nozzle inner barrel movable part to pull the relative sliding between the fixed part and the movable part, and the fixed end of the electric push rod is connected to the nozzle inner barrel fixed part, and the telescopic end of the electric push rod is connected to the nozzle inner barrel movable part; the nozzle inner barrel is arranged in the cavity formed by the nozzle shell and the nozzle outer cover, and the outer wall surface of the nozzle inner barrel fixed part is connected to the nozzle outer cover through six ribs (the outer wall surface refers to the side wall surface away from the central axis of the nozzle, and vice versa, the same below), and the ribs support the gap between the nozzle inner barrel and the nozzle outer cover, as an outer duct for the airflow to flow through in the rotating detonation mode; the nozzle inner cone is arranged in the cavity formed by the nozzle inner barrel, and the nozzle inner cone is connected to the inner wall surface of the nozzle inner barrel fixed part through ribs, supporting the inner duct for the airflow to flow through in the turbine mode. The "outer wall surface" refers to the surface away from the nozzle axis, and the inner wall surface refers to the surface close to the nozzle axis.

[0007] The nozzle outer cover includes a connecting straight section and a plug-type nozzle profile section which are arranged in sequence; the connecting straight section is arranged at the front end of the nozzle outer cover and is used to be fixedly connected to the nozzle inner tube fixing piece using ribs; the plug-type nozzle profile section is designed based on the characteristics of the outlet flow field of the rotating detonation combustion chamber, so that the aircraft can operate with maximum thrust in the rotating detonation ramjet mode, and the specific design includes contraction and expansion profile sections as the outer wall surface of the outer duct.

[0008] The inner cone of the nozzle includes a connecting straight section, an expansion profile section and a contraction profile section which are arranged in sequence; the connecting straight section is arranged at the front end of the inner cone of the nozzle, and is used to be fixedly connected with the nozzle inner tube fixing part using ribs; the expansion and contraction profile section is a structure that expands first and then contracts from front to back, and serves as the inner wall surface of the internal flow channel.

[0009] The nozzle inner barrel includes a nozzle inner barrel fixed part and a nozzle inner barrel movable part, and the nozzle inner barrel movable part includes the outer wall surface of the nozzle inner barrel movable part and the inner wall surface of the nozzle inner barrel movable part. The outer wall surface of the nozzle inner barrel movable part is designed according to the characteristics of the outlet flow field of the rotating detonation combustion chamber, so that the aircraft works with maximum thrust in the rotating detonation ramjet mode, and is similar to the plug cone surface shape of the plug nozzle. The specific design includes a connecting straight section, an expansion profile section and a contraction profile section arranged in sequence; the connecting straight section is arranged at the front end of the nozzle inner barrel movable part, and is used for sliding connection with the nozzle inner barrel fixed part; the expansion and contraction profile section is a structure that expands first and then contracts from front to back, serving as the inner wall surface of the outer duct. The inner wall surface of the movable part of the nozzle inner barrel includes a connecting straight section, a contraction profile section and an expansion profile section which are arranged in sequence; the connecting straight section is arranged at the front end of the movable part of the nozzle inner barrel, and is used for sliding connection with the fixed part of the nozzle inner barrel; the contraction-expansion profile section is a structure that contracts first and then expands from front to back, and serves as the outer wall surface of the inner flow channel.

[0010] The nozzle inner tube fixing part and the nozzle inner tube movable part are connected by balls for sliding to meet the nozzle adjustment requirements. There are six ball grooves, evenly distributed in the circumference; each ball groove has six balls. The nozzle inner tube fixing part is fixedly connected to the nozzle outer cover by six ribs, and is fixedly connected to the nozzle inner cone by four ribs.

[0011] The nozzle outer duct flow channel is formed between the nozzle outer cover and the nozzle inner tube; the nozzle inner duct flow channel is formed between the nozzle inner tube and the nozzle inner cone. Since the nozzle outer cover is a contraction-expansion profile, and the outer wall surface of the nozzle inner tube is an expansion-contraction profile, the outer duct flow channel has a point with the smallest cross-sectional area, namely, the outer duct throat; the outer wall surface of the nozzle inner tube is a contraction-expansion profile, and the nozzle inner cone is an expansion-contraction profile, so the inner duct flow channel has a point with the smallest cross-sectional area, namely, the inner duct throat.

[0012] The movable part of the nozzle inner barrel acts as a movable plug cone of the rotating detonation nozzle, and is designed together with the nozzle outer cover according to the plug nozzle principle. The profiles of the nozzle outer cover and the nozzle inner barrel are designed according to the motion law of the oblique shock wave at the rotating detonation outlet, so that the thrust reaches the optimal value under the rotating detonation mode.

[0013] All fins and the connecting parts on both sides are welded. The six fins used to support the outer duct are designed as flat rhombus columns, that is, the cross-section is a flat rhombus, and the long diagonal is parallel to the average flow direction of the airflow, so as to reduce the total pressure loss under supersonic flow in the rotating detonation mode.

[0014] The beneficial effects achieved by the technical solution of the present invention are:

[0015] By separating the inside and outside, the nozzle shape in the turbine mode and the nozzle shape in the rotating detonation ramjet mode are decoupled during the design, thereby reducing the design difficulty of the combined engine nozzle and making the combined engine work efficiently in both modes as much as possible. Especially for the engine working in the rotating detonation ramjet mode, the present invention can ensure that the outer duct flow channel is annular, and can be designed according to the plug-type nozzle structure, well matching the annular rotating detonation combustion chamber, and achieving higher thrust.

[0016] By adjusting the sliding of the movable parts of the nozzle inner tube, the throat area of ​​the combined engine inner and outer ducts can be adjusted to meet the high performance requirements of the combined engine in a wide working range under the turbine engine mode and the rotating detonation ramjet mode. The basic configuration of the axisymmetric annular converging and diverging nozzle ensures the matching of the engine flow path while achieving a simple adjustment structure and easy adjustment.

[0017] When the combined engine flies at a low Mach number, it is in turbine mode. The exhaust of the combustion chamber is converted into thrust through the inner flow channel of the nozzle. At this time, the electric push rod is extended, the movable part of the inner tube of the nozzle moves backward, and the inner throat area is increased, which can increase the engine flow rate, which is suitable for low-altitude and high-speed flight occasions; the electric push rod is shortened, the movable part of the inner tube of the nozzle moves forward, and the inner throat area is reduced, which can reduce the engine flow rate, which is suitable for high-altitude flight occasions. The throat area adjustment of the inner flow channel can make the mode transition from the turbine mode to the rotating detonation ramjet mode better. When the engine works in the rotating detonation ramjet mode with a wide speed range and high Mach, the exhaust is exhausted through the adjustable outer flow channel of the nozzle, the electric push rod is extended, and the movable part of the inner tube of the nozzle moves backward, reducing the throat area and reducing the engine flow rate; the electric push rod is shortened, and the movable part of the inner tube of the nozzle moves forward, increasing the throat area and increasing the engine flow rate, so as to achieve engine flow channel matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an isometric schematic diagram of the present invention.

[0019] Figure 2 It is the main cross-sectional view of the present invention.

[0020] Figure 3 It is a right side schematic diagram of the present invention.

[0021] Figure 4 It is a schematic diagram of the specific structural identification of the inner flow channel, outer flow channel, etc. and the inner barrel of the nozzle in the cross-sectional diagram.

[0022] Figure 5 A partial enlarged diagram illustrating the changing process and method of the inner and outer culvert throat areas. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0024] The embodiment of the present invention is designed using the following technical solutions:

[0025] 1. Nozzle structure design:

[0026] The nozzle as a whole includes a nozzle inner cone, a nozzle inner barrel (including a nozzle inner barrel fixed part and a nozzle inner barrel movable part), a nozzle outer cover and an electric push rod. The nozzle inner barrel fixed part and the nozzle inner barrel movable part are designed to be a relatively sliding structure, and the two ends of the electric push rod are respectively connected to the two parts to pull the relative sliding between them. The fixed end of the electric push rod is connected to the nozzle inner barrel fixed part, and the telescopic end is connected to the nozzle inner barrel movable part. The nozzle inner barrel is arranged in the cavity formed by the nozzle shell and the nozzle outer cover. The outer wall surface of the nozzle inner barrel fixed part is connected to the nozzle outer cover through ribs, and the ribs support the gap between the nozzle inner barrel and the nozzle outer cover as an outer duct. The nozzle inner cone is arranged in the cavity formed by the nozzle inner barrel, and is connected to the inner wall surface of the nozzle inner barrel fixed part through ribs to support the inner duct.

[0027] 2. Nozzle cover design:

[0028] The nozzle cover is designed to include a connecting straight section and a plug-type nozzle profile section. The connecting straight section is located at the front end of the nozzle cover and is used to be fixedly connected to the nozzle inner tube fixing piece using ribs. The plug-type nozzle profile section is designed based on the characteristics of the outlet flow field of the rotating detonation combustion chamber, including contraction and expansion profile sections, to achieve the maximum thrust of the aircraft in the rotating detonation ramjet mode.

[0029] 3. Nozzle inner cone design:

[0030] The nozzle inner cone is designed to include a connecting straight section, an expansion profile section and a contraction profile section. The connecting straight section is arranged at the front end of the nozzle inner cone and is used to be fixedly connected with the nozzle inner tube fixing part using ribs. The expansion and contraction profile section is designed to be a structure that expands first and then contracts from front to back to realize the inner wall surface of the inner flow channel.

[0031] 4. Design of movable parts of nozzle inner tube:

[0032] The outer wall surface of the movable part of the nozzle inner tube is designed according to the characteristics of the outlet flow field of the rotating detonation combustion chamber, and is similar to the surface shape of the plug cone of the plug nozzle, including a connecting straight section, an expansion profile section and a contraction profile section. The inner wall surface of the movable part of the nozzle inner tube is designed to include a connecting straight section, a contraction profile section and an expansion profile section. Ball bearings are used for sliding connection between the nozzle inner tube fixed part and the movable part of the nozzle inner tube to provide the nozzle adjustment requirements. The ball bearing grooves are evenly distributed circumferentially, and there are multiple balls in each ball bearing groove.

[0033] 5. Throat design:

[0034] Since the nozzle cover is a contraction-expansion profile, and the outer wall of the nozzle inner tube is an expansion-contraction profile, the outer culvert flow channel has its smallest cross-sectional area, which is the outer culvert throat. The outer wall of the nozzle inner tube is a contraction-expansion profile, and the nozzle inner cone is an expansion-contraction profile, so the inner flow channel has its smallest cross-sectional area, which is the inner throat.

[0035] 6. Adjustment mechanism design:

[0036] The telescopic movement of the electric push rod enables the relative sliding between the movable part of the nozzle inner tube and the fixed part of the nozzle inner tube, thereby adjusting the throat area of ​​the inner and outer ducts. According to the requirements of the flight conditions, the telescopic length of the electric push rod is adjusted through the control system to achieve precise adjustment of the throat area.

[0037] like Figures 1 to 5 As shown, the row nozzle of the embodiment of the present invention is composed of a nozzle cover 1, a nozzle inner barrel 2, a nozzle inner cone 3, and an electric push rod 4, and the nozzle inner barrel 2 is composed of a nozzle inner barrel movable part 5 and a nozzle inner barrel fixing part 6. Among these components, the nozzle cover 1 is firmly mounted on the nozzle inner barrel fixing part 6 through 6 ribs 7, and the nozzle inner cone 3 is also firmly mounted on the nozzle inner barrel fixing part 6 through 4 ribs 7. Both sides of each rib 7 are fixed by welding to ensure the stability of the structure. The nozzle inner barrel movable part 5 is connected to the nozzle inner barrel fixing part 6 through a ball 8 to achieve a sliding connection on the nozzle inner barrel fixing part 6. This design enables the nozzle inner barrel movable part 5 to move forward and backward flexibly. The four electrical push rods 4 are respectively connected to the nozzle inner tube fixed part 6 and the nozzle inner tube movable part 5. When the inner and outer ducts need to be adjusted, the electrical push rods 4 pull the nozzle inner tube movable part 5 to move forward and backward to achieve the purpose of adjusting the inner and outer ducts.

[0038] Figure 3 This is a right view of the nozzle of the present invention. Six fins of the annular outer duct and four fins of the annular inner duct can be seen, and the airflow can pass through the gaps between the fins. It can be seen that the airflow can flow through the nozzle cover and the nozzle inner barrel, which is the outer duct flow channel; the airflow can flow through the nozzle inner barrel and the nozzle inner cone, which is the inner duct flow channel.

[0039] like Figure 4As shown, the inner flow channel is composed of the inner cone 3 of the nozzle and the inner wall surface of the nozzle inner tube 2, and the airflow can flow through the inner flow channel. The so-called inner wall surface refers to the surface close to the central axis of the nozzle. For the nozzle inner tube 2, it is a general term for the surface of the fixed part 6 and the movable part 5 close to the nozzle axis. The outer duct flow channel is composed of the outer wall surface of the nozzle outer cover 1 and the inner tube 2 of the nozzle, and the airflow can also flow through the outer duct flow channel.

[0040] The inner and outer walls of the nozzle inner tube 2, the nozzle outer cover 1 and the wall of the nozzle inner cone 3 are all specially designed, so that the nozzle outer cover 1 and the outer wall of the nozzle inner tube movable part 5 are closest to each other on the surface. This place is the place where the outer culvert flow channel has the smallest area, which is called the outer culvert throat (such as Figure 4 ). The outer duct throat is the narrowest place when the outer duct airflow passes through, which limits the flow rate of the outer duct airflow. Similarly, the inner cone 3 of the nozzle and the inner wall surface of the movable part 5 of the inner tube of the nozzle also form an inner duct, and the part with the smallest flow area is called the inner duct throat (such as Figure 4 ), is the narrowest place when the implied airflow passes through, limiting the flow rate of the implied airflow.

[0041] At the same time, the shape of each duct follows the law of first contraction and then expansion, so as to follow the design principle of the Laval nozzle. When the incoming airflow is subsonic, the airflow can be accelerated to supersonic speed after passing through the nozzle of the present invention; when the incoming airflow is the typical coexistence of subsonic and supersonic speeds at the outlet of the rotating detonation combustion chamber, that is, part of the airflow is subsonic in the circumferential direction and the other part is supersonic, after the airflow passes through the nozzle of the present invention, the airflow can be uniformly changed to the speed of sound in the throat, and then accelerated to supersonic speed, thereby improving the thrust of the rotating detonation ramjet mode and reducing its circumferential non-uniformity.

[0042] The engine requires different optimal working flow rates under different working conditions, so the engine flow rate needs to be adjusted. Figure 5 As shown, the areas of the outer culvert throat and the inner culvert throat are variable. The specific change method is to use the electric push rod to pull the nozzle inner barrel movable part to move forward and backward, change the relative position relationship between the nozzle inner barrel movable part and the nozzle outer cover, and between the nozzle inner barrel movable part and the nozzle inner cone, so that the shape of the inner and outer culvert flow channels changes, and the areas of the inner and outer culvert throats change. For example, when the electric push rod pulls the nozzle inner barrel movable part to move forward (forward and backward are based on the direction of fluid flow, Figure 5The specific direction is indicated), the inflection point of the inner wall of the duct moves forward, and the distance from the inflection point of the outer wall of the duct on the nozzle cover becomes farther, the area of ​​the duct throat becomes larger, and a larger flow of gas from the duct can pass through. The reverse is true when moving backward. When the movable part of the nozzle inner tube moves forward, the inflection point of the outer wall of the conduit also moves forward, making it closer to the inflection point of the inner wall of the conduit on the inner cone of the nozzle, and the area of ​​the conduit throat becomes smaller, and a smaller flow of gas from the duct throat can pass through, increasing the pressure of the engine combustion chamber to which the nozzle is connected.

[0043] When the engine is in different working modes, the nozzle of the present invention has different working modes. The first working mode is the working mode of the engine in the turbine working mode, and the second working mode is the working mode of the engine in the rotating detonation ramjet working mode.

[0044] The first working method:

[0045] The engine is in turbine working mode. The airflow is ejected through the inner flow channel of the nozzle of the present invention to generate thrust, while the outer flow channel does not work. Specifically, when the engine is started at zero speed or running at low speed, it works in turbine mode, the turbine core engine in the center of the engine rotates, the airflow flows through the core engine, and is discharged into the atmosphere and generates thrust through the compression-combustion-expansion-exhaust process, wherein the nozzle of the present invention undertakes the exhaust process, and the airflow needs to be discharged from the inner flow channel. The inner flow channel is composed of the inner wall surface of the nozzle inner tube and the inner cone of the nozzle, and is welded and fixed by four ribs to ensure that the shape of the inner flow channel remains stable under the dynamics of the airflow. The cross-sectional area change law and the profile change law of the inner flow channel are set according to the gas dynamics. When the cross-sectional area changes from front to back, it first decreases and then increases, so as to follow the design criteria of the Laval nozzle, so that the airflow flowing through the inner flow channel is accelerated to the speed of sound at the minimum cross-sectional area, and then accelerates to the supersonic speed when the cross-sectional area is expanded, so as to provide greater thrust. At this time, all or almost all of the gas flowing through the nozzle flows through the inner flow channel, and the outer flow channel does not work.

[0046] When the environment changes, such as when the aircraft flies to a high altitude, Figure 5As shown, the movable part of the inner tube of the nozzle is pulled forward by the electric push rod, the shape of the inner flow channel changes, the inner throat area at the smallest cross-sectional area of ​​the inner flow channel becomes smaller, and the engine flow rate decreases. When the aircraft speeds up or flies at a low altitude, the movable part of the inner tube of the nozzle is pulled backward by the electric push rod, the shape of the inner flow channel changes, the inner throat area becomes larger, and the engine flow rate becomes larger. It should be noted that, according to the different relative positions of the inflection points of the inner cone of the nozzle and the inner wall surface of the movable part of the inner tube of the nozzle, the forward or backward movement of the movable part of the inner tube of the nozzle under the action of the electric push rod may cause the change law of the cross-sectional area of ​​the inner throat to be opposite to the above conclusion, and this example is still within the scope of protection of this application. For example, if the inflection point of the inner wall surface of the inner flow channel is before the inflection point of the outer wall surface of the inner flow channel, shortening the electric push rod will cause the inner throat area to expand, while extending the electric push rod will cause the inner throat area to shrink.

[0047] The second working method:

[0048] The engine operates in a rotating detonation ramjet mode. The airflow is ejected through the outer duct of the nozzle of the present invention to generate thrust, while the inner duct does not work. Specifically, after the engine runs in the turbine mode (the nozzle is running in the first working mode) for a period of time, the aircraft is accelerated to the minimum speed requirement for the rotating detonation ramjet mode, and switches to the rotating detonation ramjet mode to improve the engine performance. At this time, the turbine core engine stops, and only the rotating detonation combustion chamber outside the core engine works. The airflow flows through the rotating detonation combustion chamber outside the core engine, and after adding fuel, the rotating detonation combustion process generates combustion gas and is discharged through the outer duct of the nozzle of the present invention. The outer duct is composed of the outer wall of the nozzle cover and the inner barrel of the nozzle, and is welded and fixed by six fins. The cross-section of the fin is a flat rhombus, which is suitable for supersonic airflow. At this time, the airflow flows entirely through the outer duct, and its cross-sectional area change law and profile change law also follow the aerodynamic design, and follow the Laval nozzle design principle of first contraction and then expansion. The design method of the plug nozzle can be used in actual design. At this time, the airflow in front of the nozzle of the present invention is a coexistence of subsonic and supersonic speeds, that is, at different circumferential positions, part of the airflow is subsonic, and the other part is supersonic. The airflow is uniformly changed to the speed of sound at the throat of the culvert, and is accelerated to the supersonic speed in the rear expansion channel. However, the shape of the culvert flow channel is not fixed, and its shape can be changed by moving the movable part of the nozzle inner tube by an electric push rod, especially changing the cross-sectional area of ​​the culvert throat where the cross-sectional area of ​​the culvert flow channel is the smallest. Figure 5As shown, when the electric push rod is controlled to shorten, the movable part of the inner tube of the nozzle moves forward, and the cross-sectional area of ​​the outer throat becomes larger; when the electric push rod is controlled to extend, the movable part of the inner tube of the nozzle moves backward, and the cross-sectional area of ​​the outer throat becomes smaller. When the aircraft is operating at a lower altitude, the ambient pressure is high, and it is necessary to increase the outer throat area of ​​the outer tube through the above method, increase the flow rate of the engine, and reduce the nozzle expansion ratio to reduce the pressure of the rotating detonation combustion chamber so that it can operate normally, and at the same time, match the pressure of the ejected gas with the ambient pressure; similarly, when the aircraft is operating at a higher altitude, the ambient pressure is low, and it is necessary to reduce the outer throat area of ​​the outer tube through the above method, reduce the flow rate of the engine, and increase the nozzle expansion ratio to increase the pressure of the rotating detonation combustion chamber so that it can operate normally, and at the same time, match the pressure of the ejected gas with the ambient pressure. It should be noted that, according to the different relative positions of the inflection points of the outer wall of the nozzle cover and the movable part of the nozzle inner tube, the forward or backward movement of the nozzle cover under the action of the electric push rod may cause the change law of the cross-sectional area of ​​the outer culvert throat to be opposite to the above conclusion, and this example is still within the scope of protection of this application. For example, if the inflection point of the outer wall of the outer culvert flow channel is before the inflection point of the inner wall of the outer culvert flow channel, the shortening of the electric push rod will cause the outer culvert throat area to decrease, while the extension of the electric push rod will cause the outer culvert throat area to expand.

[0049] The embodiment of the present invention provides an adjustable nozzle adapted to the high-frequency time-varying flow field of a rotating detonation combination engine, including a nozzle inner cone, a nozzle outer cover, a nozzle inner barrel and an electric push rod; wherein the nozzle inner barrel is composed of two parts: a nozzle inner barrel movable part and a nozzle inner barrel fixed part. An outer culvert flow channel is formed between the nozzle outer cover and the outer wall surface of the nozzle inner barrel, and an inner culvert flow channel is formed between the inner wall surface of the nozzle inner barrel and the nozzle inner cone. Among them, the profile design of the outer culvert flow channel is designed according to the outlet flow field of the rotating detonation engine, and the movable part of the nozzle inner barrel acts as a movable plug cone of the plug-type nozzle, and the axisymmetric annular outer culvert matches the annular rotating detonation engine combustion chamber, ensuring that the engine achieves high thrust in the rotating detonation mode, while the nozzle can be adjusted under different working conditions of the engine in the rotating detonation mode. The adjustment of the outer culvert throat area depends on the traction of the electric push rod on the movable part of the nozzle inner barrel, which can slide on the nozzle inner barrel fixed part to achieve the purpose of adjusting the outer culvert throat area. At the same time, this adjustment method can also adjust the inner throat area. When the combined engine is in turbine mode at low altitude and low Mach number, the exhaust of the inner flow channel is used to generate thrust. When the combined engine is in rotating detonation ramjet mode at high altitude and high Mach number, the exhaust of the outer flow channel is used to generate thrust. When the engine is working in these two modes, the extension of the electric push rod is adjusted according to the changes in the pressure of the engine working environment, and then the area of ​​the inner and outer throats is adjusted, so that the working conditions of the nozzle are matched with the environmental conditions, so as to improve the heat-to-work conversion efficiency of the rotating detonation ramjet combined engine within a wide speed range.

[0050] The above embodiments are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An adjustable nozzle adapted to the high-frequency time-varying flow field of a rotating detonation combined engine, characterized in that It includes a nozzle inner cone, a nozzle inner barrel, a nozzle outer cover and an electric push rod; The nozzle inner cone is arranged in the cavity formed by the nozzle inner barrel, and the nozzle inner cone includes a connecting straight section, an expansion profile section and a contraction profile section arranged in sequence, the connecting straight section is used to be fixedly connected with the inner wall surface of the nozzle inner barrel fixing part through ribs, and supports the inner flow channel for the airflow to flow through under the turbine mode, and the expansion profile section and the contraction profile section serve as the inner wall surface of the inner flow channel; The nozzle inner barrel comprises two parts, namely, a nozzle inner barrel fixing part and a nozzle inner barrel movable part, which can slide relative to each other. The nozzle inner barrel is arranged in a cavity formed by a nozzle shell and a nozzle outer cover. The outer wall surface of the nozzle inner barrel fixing part is connected to the nozzle outer cover through ribs. The ribs support the gap between the nozzle inner barrel and the nozzle outer cover, which serves as an outer duct for airflow in a rotating detonation mode to flow through. The outer wall surface of the nozzle inner barrel movable part is designed according to the characteristics of the outlet flow field of the rotating detonation combustion chamber, and comprises a connecting straight section, an expansion profile section and a contraction profile section which are arranged in sequence, which serve as the inner wall surface of the outer duct. The inner wall surface of the nozzle inner barrel movable part comprises a connecting straight section, a contraction profile section and an expansion profile section which are arranged in sequence, which serve as the outer wall surface of the inner duct. The nozzle cover comprises a connecting straight section and a plug-type nozzle profile section which are arranged in sequence, wherein the connecting straight section is used to be fixedly connected with the nozzle inner tube fixing member using ribs, and the plug-type nozzle profile section serves as the outer wall surface of the outer duct; The two ends of the electric push rod are respectively connected to the nozzle inner tube fixed part and the nozzle inner tube movable part to pull the relative sliding between the two, the fixed end of the electric push rod is connected to the nozzle inner tube fixed part, and the telescopic end of the electric push rod is connected to the nozzle inner tube movable part; The nozzle inner tube fixing part and the nozzle inner tube movable part are connected by a ball for sliding, the nozzle inner tube fixing part and the nozzle outer cover are connected by a rib for fixed connection, and the nozzle inner cone is connected by a rib for fixed connection.

2. An adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that The movable part of the nozzle inner barrel acts as a movable plug cone of the rotating detonation nozzle, and is designed together with the nozzle outer cover according to the plug nozzle principle. The profiles of the nozzle outer cover and the nozzle inner barrel are designed according to the motion law of the oblique shock wave at the rotating detonation outlet, so that the thrust reaches the optimal value under the rotating detonation mode.

3. An adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that The expansion profile section and the contraction profile section of the nozzle inner cone are structures that expand first and then contract from front to back, and are used to adjust the flow field characteristics of the inner flow channel under the turbine mode.

4. The adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that The expansion profile section and the contraction profile section of the inner wall surface of the movable part of the nozzle inner tube are structures that first contract and then expand from front to back, and are used to further adjust the flow field characteristics of the inner flow channel under the turbine mode.

5. The adjustable nozzle adapted to the high frequency time-varying flow field of the rotating detonation combined engine as claimed in claim 1, characterized in that There are a total of 6 ball grooves between the nozzle inner tube fixed part and the nozzle inner tube movable part, which are evenly distributed in the circumferential direction. There are 6 balls in each ball groove to provide smooth sliding required for nozzle adjustment.

6. An adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that A nozzle duct channel is formed between the nozzle outer cover and the nozzle inner tube, and a nozzle inner tube channel is formed between the nozzle inner tube and the nozzle inner cone. The duct channel and the inner tube channel have their smallest cross-sectional areas, namely, the duct throat and the inner tube throat, respectively.

7. An adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that By adjusting the telescopic adjustment of the electric push rod, the sliding of the movable part of the nozzle inner tube is achieved, thereby adjusting the throat area of ​​the inner and outer ducts to meet the high performance requirements of the combined engine in a wide working range under the turbine engine mode and the rotating detonation ramjet mode.

8. The adjustable nozzle adapted to the high frequency time-varying flow field of the rotating detonation combined engine as claimed in claim 1, characterized in that All fins and the connecting parts on both sides are welded; the six fins used to support the outer duct are designed as flat rhombus columns, that is, the cross-section is a flat rhombus, and the long diagonal is parallel to the average flow direction of the airflow, so as to reduce the total pressure loss under supersonic flow in the rotating detonation mode.

9. The adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that The design of the adjustable nozzle allows the nozzle shape in the turbine mode and the nozzle shape in the rotating detonation ramjet mode to be decoupled during design, thereby reducing the design difficulty of the combined engine nozzle.

10. An adjustable nozzle adapted to the high frequency time-varying flow field of a rotating detonation combined engine as claimed in claim 1, characterized in that The adjustable nozzle ensures that the outer duct is annular through the adjustability of the inner and outer rows and the throat area, and is well adapted to the annular rotating detonation engine, thereby achieving excellent performance of the aircraft in the rotating detonation ramjet mode.

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