An adjustable nozzle adapted to the high frequency time-varying flow field of a rotary detonation combined engine

Abstract

An adjustable nozzle adapting to high-frequency time-varying flow field of rotary detonation combined engine relates to the field of combined power engine. It is composed of a nozzle inner cone, a nozzle outer cover, a nozzle inner cylinder composed of a movable part and a fixed part, and an electric push rod. Its characteristics are that the outer channel flow is designed according to the outlet flow field of the rotary detonation engine, matched with the annular rotary detonation engine combustion chamber, and high thrust is ensured. The movable part of the nozzle inner cylinder is a movable plug cone of the plug nozzle, which slides on the nozzle inner cylinder fixed part through the traction of the electric push rod, so as to realize the adjustment of the area of the outer channel and the inner channel throat. The design allows the engine to use the inner channel flow exhaust in the low-altitude low-Mach number turbine mode and the outer channel flow exhaust in the high-altitude high-Mach number rotary detonation ram mode. By adjusting the extension amount of the electric push rod, the working environment pressure change of the engine is matched, the nozzle working is optimized, and the thermal power conversion efficiency of the rotary detonation ram combined engine in a wide speed range is improved.

Description

Technical Field

[0001] This invention relates to the field of combined-power engines, specifically to an adjustable nozzle that adapts to the high-frequency time-varying flow field of a rotating detonation combined-power engine. Background Technology

[0002] Rotating detonation is a novel combustion form with advantages such as rapid heat release rate and self-pressurization. Replacing conventional ramjet engines with rotating detonation ramjet engines can further broaden the speed range of combined engines. The turbine engine mode is used at subsonic speeds, transitioning to the rotating detonation ramjet mode at supersonic speeds. The exit flow field of the rotating detonation combustor is a typical high-frequency, time-varying flow field, requiring specially designed nozzles. Studies show that plug-type nozzles perform well in rotating detonation engines; their annular characteristics can effectively connect with the annular shape of the rotating detonation combustor, resulting in a more uniform and efficient exhaust flow. However, currently designed turbine-based ramjet combined engine nozzles are often integrated designs and are frequently two-dimensional, with a square nozzle exit. If used in a rotating detonation ramjet engine, their shape is unsuitable for the annular rotating detonation combustor, necessitating a transition section and increasing flow losses. For a turbine-based rotary detonation ramjet combined engine, it is necessary to design a nozzle that can ensure good performance in both turbine and rotary detonation ramjet operating modes.

[0003] Due to the high-frequency, time-varying flow field characteristics of rotating detonation, an adjustable nozzle needs to be designed. Adjusting the inner bypass duct can ensure good engine performance in turbine mode, while adjusting the outer bypass duct can broaden the operating range of rotating detonation ramjet mode, further expanding the aircraft's operating envelope. Summary of the Invention

[0004] The purpose of this invention is to provide an adjustable nozzle that adapts to the high-frequency time-varying flow field of a rotating detonation combined engine. By separating the exhaust from the inner and outer bypass ducts and adjusting the throat area, the combined engine can achieve separate exhaust from the inner and outer bypass ducts, while ensuring that the outer bypass duct is an annular adjustable plug nozzle structure, which is well-matched with the annular rotating detonation engine. This ensures the aircraft's excellent performance in the rotating detonation ramjet mode. Furthermore, the throat area of ​​the inner and outer bypass ducts can be adjusted according to flight conditions to ensure engine flow channel matching, enabling the combined engine to operate efficiently and stably over a wide speed range.

[0005] To achieve the above objectives, 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 rotary detonation combined engine includes an inner cone, an inner cylinder, an outer cover, and an electric push rod; the inner cylinder comprises two parts: a fixed part and a movable part, which can slide relative to each other. The electric push rod is connected at both ends to the nozzle inner cylinder fixing component and the nozzle inner cylinder movable component, respectively, to pull the relative sliding between the fixing component and the movable component. The fixed end of the electric push rod is connected to the nozzle inner cylinder fixing component, and the telescopic end of the electric push rod is connected to the nozzle inner cylinder movable component. The nozzle inner cylinder is located in the cavity formed by the nozzle shell and the nozzle outer cover. The outer wall surface of the nozzle inner cylinder fixing component and the nozzle outer cover are connected by six ribs (the outer wall surface refers to the wall surface away from the nozzle central axis, and vice versa). The ribs support the gap between the nozzle inner cylinder and the nozzle outer cover, serving as an outer bypass channel for the airflow under the rotating detonation mode. The nozzle inner cone is located in the cavity formed by the nozzle inner cylinder, and the nozzle inner cone is connected to the inner wall surface of the nozzle inner cylinder fixing component by ribs, supporting the inner bypass channel for the airflow under 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 arranged in sequence; the connecting straight section is located at the front end of the nozzle outer cover and is used to fix it to the nozzle inner cylinder fixing component using ribs; the plug-type nozzle profile section is designed according to the characteristics of the flow field at the exit of the rotating detonation combustion chamber, so that the aircraft can work with maximum thrust under the rotating detonation ramjet mode. In the specific design, it includes contraction and expansion profile sections as the outer wall surface of the bypass channel.

[0008] The nozzle inner cone includes a connecting straight section, an expanding surface section, and a contracting surface section arranged sequentially. The connecting straight section is located at the front end of the nozzle inner cone and is used to fix it to the nozzle inner cylinder fixing component using ribs. The expanding and contracting surface section has a structure that expands and then contracts from front to back, serving as the inner wall surface of the inner flow channel.

[0009] The nozzle inner cylinder includes a fixed part and a movable part, and the movable part includes an outer wall surface and an inner wall surface. The outer wall surface of the movable part is designed according to the flow field characteristics of the rotary detonation combustion chamber exit, so that the aircraft can operate with maximum thrust under the rotary detonation ramjet mode. It is similar to the surface shape of the plug cone of a plug nozzle. Specifically, it includes a connecting straight section, an expanding section, and a contracting section arranged in sequence. The connecting straight section is located at the front end of the movable part and is used for sliding connection with the fixed part. The expanding and contracting section is a structure that expands and then contracts from front to back, serving as the inner wall surface of the outer bypass channel. The inner wall surface of the movable part of the nozzle inner cylinder includes a connecting straight section, a contraction-shaped surface section and an expansion-shaped surface section arranged in sequence; the connecting straight section is located at the front end of the movable part of the nozzle inner cylinder and is used to make a sliding connection with the fixed part of the nozzle inner cylinder; the contraction-expansion-shaped surface section is a structure that contracts first and then expands from front to back, serving as the outer wall surface of the inner flow channel.

[0010] The nozzle inner cylinder fixing component and the nozzle inner cylinder movable component are slidably connected by ball bearings to provide nozzle adjustment. There are a total of six ball bearing grooves, evenly distributed circumferentially; each ball bearing groove contains six balls. The nozzle inner cylinder fixing component is fixedly connected to the nozzle outer cover by six ribs and to the nozzle inner cone by four ribs.

[0011] The nozzle outer casing and the nozzle inner cylinder form an outer flow channel; the nozzle inner cylinder and the nozzle inner cone form an inner flow channel. Since the nozzle outer casing has a contraction-expansion profile and the outer wall of the nozzle inner cylinder has an expansion-contraction profile, the outer flow channel has a minimum cross-sectional area, i.e., the outer throat. Similarly, the outer wall of the nozzle inner cylinder has a contraction-expansion profile and the nozzle inner cone has an expansion-contraction profile; therefore, the inner flow channel has a minimum cross-sectional area, i.e., the inner throat.

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

[0013] All ribs and side connectors are welded. The six ribs used to support the outer bypass channel are designed as flat rhomboid prisms, that is, the cross-section is flat rhomboid 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 this invention are:

[0015] By separating the nozzles into inner and outer sections, the nozzle shape in turbine mode and rotating detonation ramjet mode are decoupled during the design process, thereby reducing the design difficulty of the combined engine nozzle and enabling the combined engine to operate efficiently in both modes. Especially for the engine operating in rotating detonation ramjet mode, this invention can ensure that the bypass channel is annular and can be designed according to the plug nozzle structure, which can be well matched with the annular rotating detonation combustion chamber and achieve higher thrust.

[0016] By sliding and adjusting the movable parts of the nozzle inner cylinder, the throat area of ​​the inner and outer bypass ducts of the combined engine can be adjusted, meeting the high-performance requirements of the combined engine over a wide operating range under both turbine engine mode and rotating detonation ramjet mode. Its axisymmetric annular converging-diverging nozzle configuration ensures engine flow channel matching while achieving simplicity in the adjustment structure and ease of adjustment.

[0017] When the combined engine flies at low Mach numbers, it operates in turbine mode. The exhaust gas from the combustion chamber is converted into thrust through the nozzle's internal flow channels. In this mode, extending the electric pushrod moves the movable part of the nozzle inner cylinder rearward, increasing the throat area and thus increasing engine flow, suitable for low-altitude, high-speed flight. Conversely, shortening the electric pushrod moves the movable part of the nozzle inner cylinder forward, decreasing the throat area and thus reducing engine flow, suitable for high-altitude flight. Adjusting the throat area of ​​the internal flow channels allows for a smoother transition from turbine mode to rotating detonation ramjet mode. When the engine operates in a wide-speed-range, high-Mach rotating detonation ramjet mode, exhaust gas is exhausted through the adjustable outer bypass channel of the nozzle. Extending the electric pushrod moves the movable part of the nozzle inner cylinder rearward, reducing the throat area and decreasing engine flow; shortening the electric pushrod moves the movable part of the nozzle inner cylinder forward, increasing the throat area and increasing engine flow, thus achieving engine flow channel matching. Attached Figure Description

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

[0019] Figure 2 This is a front sectional view of the present invention.

[0020] Figure 3 This is a right-side view of the present invention.

[0021] Figure 4 This is a schematic diagram showing the specific structural markings of the inner flow channel, outer flow channel, and nozzle inner cylinder in the cross-sectional view.

[0022] Figure 5 This is a partially enlarged diagram illustrating the process and manner of change in the area of ​​the inner and outer culvert throats. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects of this invention clearer and more understandable, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of this invention and should not be construed as limiting the scope of protection of this invention.

[0024] The embodiments of the present invention are designed using the following technical solutions:

[0025] 1. Nozzle structure design:

[0026] The nozzle assembly comprises an inner cone, an inner cylinder (including a fixed component and a movable component), an outer casing, and an electric actuator. The fixed and movable components of the inner cylinder are designed to slide relative to each other, with the electric actuator connecting these two parts at both ends to facilitate this relative sliding. The fixed end of the electric actuator connects to the fixed component, and the telescopic end connects to the movable component. The inner cylinder is located within the cavity formed by the nozzle housing and the outer casing. The outer wall of the fixed component connects to the outer casing via ribs, which support the gap between the inner cylinder and the outer casing, serving as an outer flow channel. The inner cone is located within the cavity formed by the inner cylinder and connects to the inner wall of the fixed component via ribs, supporting the inner flow channel.

[0027] 2. Nozzle outer cover design:

[0028] The nozzle casing 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 casing and is used to securely connect to the nozzle inner cylinder using ribs. The plug-type nozzle profile section is designed based on the flow field characteristics at the exit of the rotating detonation combustion chamber, and includes contraction and expansion profile sections to achieve maximum thrust for the aircraft in the rotating detonation ramjet mode.

[0029] 3. Nozzle internal cone design:

[0030] The nozzle inner cone is designed to include a connecting straight section, an expanding surface section, and a contracting surface section. The connecting straight section is located at the front end of the nozzle inner cone and is used to fix it to the nozzle inner cylinder using ribs. The expanding-contracting surface section is designed to expand and then contract from front to back to achieve the inner wall surface of the inner flow channel.

[0031] 4. Design of movable parts in the nozzle inner cylinder:

[0032] The outer wall surface of the movable part of the nozzle inner cylinder is designed to resemble the surface shape of a plug cone in a plug nozzle, based on the flow field characteristics at the exit of the rotating detonation combustion chamber. It includes a connecting straight section, an expanding section, and a contracting section. The inner wall surface of the movable part of the nozzle inner cylinder is designed to include a connecting straight section, a contracting section, and an expanding section. A ball bearing is used for sliding connection between the fixed part of the nozzle inner cylinder and the movable part to accommodate nozzle adjustment needs. Ball bearing grooves are evenly distributed circumferentially, with multiple balls in each groove.

[0033] 5. Throat design:

[0034] Because the nozzle outer casing has a contraction-expansion profile and the outer wall of the nozzle inner cylinder has an expansion-contraction profile, the outer bypass channel has a minimum cross-sectional area, which is the outer bypass throat. Similarly, the outer wall of the nozzle inner cylinder has a contraction-expansion profile and the nozzle inner cone has an expansion-contraction profile; therefore, the inner bypass channel has a minimum cross-sectional area, which is the inner bypass throat.

[0035] 6. Regulation mechanism design:

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

[0037] like Figures 1-5 As shown, the multi-row nozzle of this embodiment of the invention consists of a nozzle outer cover 1, a nozzle inner cylinder 2, a nozzle inner cone 3, and an electric push rod 4. The nozzle inner cylinder 2 is composed of a movable nozzle inner cylinder 5 and a fixed nozzle inner cylinder 6. In these components, the nozzle outer cover 1 is securely mounted to the nozzle inner cylinder fixed cylinder 6 by six ribs 7, while the nozzle inner cone 3 is similarly securely mounted to the nozzle inner cylinder fixed cylinder 6 by four ribs 7. Each rib 7 is fixed by welding on both sides to ensure structural stability. The movable nozzle inner cylinder 5 is connected to the nozzle inner cylinder fixed cylinder 6 by ball bearings 8, achieving a sliding connection on the nozzle inner cylinder fixed cylinder 6. This design allows the movable nozzle inner cylinder 5 to move flexibly back and forth. Four electric push rods 4 are respectively connected to the nozzle inner cylinder fixed part 6 and the nozzle inner cylinder movable part 5. When it is necessary to adjust the inner and outer flow channels, the electric push rods 4 pull the nozzle inner cylinder movable part 5 to move back and forth, so as to achieve the purpose of adjusting the inner and outer flow channels.

[0038] Figure 3 This is a right view of the nozzle of the present invention. Six ribs of the annular outer bypass duct and four ribs of the annular inner bypass duct can be seen, with the airflow passing through the gaps between the ribs. Airflow can be seen flowing between the nozzle outer casing and the nozzle inner cylinder; this is the outer bypass duct. Airflow can also flow between the nozzle inner cylinder and the nozzle inner cone; this is the inner bypass duct.

[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 inner cylinder 2 of the nozzle, through which airflow can pass. The inner wall surface refers to the surface near the central axis of the nozzle; for the inner cylinder 2, it is the collective term for the surfaces of the fixed part 6 and the movable part 5 near the nozzle axis. The outer flow channel is composed of the outer cover 1 of the nozzle and the outer wall surface of the inner cylinder 2 of the nozzle, through which airflow can also pass.

[0040] The inner and outer walls of the nozzle inner cylinder 2, the nozzle outer cover 1, and the inner cone 3 of the nozzle are all specially designed. This results in the nozzle outer cover 1 and the outer wall of the movable part 5 of the nozzle inner cylinder having the closest point on the surface. This point is the area of ​​the outer bypass channel with the smallest area, called the outer bypass throat (e.g., Figure 4 The bypass throat is the narrowest point where the bypass airflow passes through, limiting the flow rate. Similarly, the inner cone 3 of the nozzle and the inner wall of the movable part 5 of the nozzle inner cylinder also form an inner flow channel, the point of which has the smallest flow area is called the inner throat (e.g., Figure 4 ( ) is the narrowest point through which the internal airflow passes, limiting the flow rate of the internal airflow.

[0041] Meanwhile, the shape of each duct follows the rule of first contracting and then expanding, in accordance with 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 this invention. When the incoming airflow is a typical case of subsonic and supersonic coexistence 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, the airflow can uniformly change to sonic speed in the throat after passing through the nozzle of this invention, and then be accelerated to supersonic speed, thereby improving the thrust of the rotating detonation ramjet mode and reducing its circumferential non-uniformity.

[0042] An engine requires different optimal flow rates under different operating conditions, therefore the engine's flow rate needs to be adjusted. For example... Figure 5 As shown, the areas of the outer and inner throats are variable. Specifically, this variation occurs by using an electric actuator to move the movable part of the nozzle inner cylinder forward and backward, altering the relative positions between the movable part and the nozzle outer casing, and between the movable part and the nozzle inner cone. This results in changes to the shapes of the inner and outer flow channels, as well as the areas of the inner and outer throats. For example, when the electric actuator moves the movable part of the nozzle inner cylinder forward (forward and backward refer to the direction of fluid flow), Figure 5(With a specific direction indicated), the inflection point of the outer bypass duct's inner wall profile moves forward, increasing the distance between it and the inflection point of the outer bypass duct's outer wall profile on the nozzle cover. This increases the area of ​​the outer bypass throat, allowing a larger flow rate of gas to pass through. Conversely, moving backward has the opposite effect. When the moving part of the nozzle's inner cylinder moves forward, the inflection point of the inner bypass duct's outer wall profile also moves forward, bringing it closer to the inflection point of the inner bypass duct's inner wall profile on the nozzle's inner cone. This reduces the area of ​​the inner bypass throat, allowing a smaller flow rate of gas to pass through the outer bypass throat, thus increasing the pressure in the engine combustion chamber to which the nozzle is connected.

[0043] The nozzle of this invention operates in different modes depending on the engine's operating conditions. The first mode is when the engine is in turbine mode, and the second mode is when the engine is in rotary detonation ramjet mode.

[0044] The first working method:

[0045] The engine operates in turbine mode. Airflow is ejected through the inner channel of the nozzle of this invention, generating thrust, while the outer bypass channel remains inactive. Specifically, when the engine starts at zero speed or runs at low speed, it operates in turbine mode. The turbine core in the center of the engine rotates, and airflow flows through the core, undergoing compression-combustion-expansion-exhaust processes before being discharged into the atmosphere, generating thrust. The nozzle of this invention handles the exhaust process, and the airflow exits through the inner channel. The inner channel is formed by the inner wall of the nozzle inner cylinder and the nozzle inner cone, and is fixed by four welded ribs to ensure the stability of the inner channel's shape under aerodynamic forces. The cross-sectional area and profile of the inner channel are designed according to gas dynamics. The cross-sectional area decreases first and then increases from front to back, following the design principles of Laval nozzles. This ensures that the airflow accelerates to sonic speed at the point of minimum cross-sectional area in the inner channel, and then accelerates to supersonic speed as the cross-sectional area expands thereafter, providing greater thrust. At this time, all or almost all of the gas flowing through the nozzle passes through the inner channel, and the outer bypass channel remains inactive.

[0046] When the environment changes, such as when an aircraft flies to a high altitude, Figure 5As shown, the electric actuator pulls the movable part of the nozzle inner cylinder forward, changing the shape of the inner flow channel. The area of ​​the inner throat, where the cross-sectional area of ​​the inner flow channel is the smallest, decreases, resulting in a reduction in engine flow. When the aircraft accelerates or flies at low altitude, the electric actuator pulls the movable part of the nozzle inner cylinder backward, changing the shape of the inner flow channel, increasing the area of ​​the inner throat, and increasing engine flow. It should be noted that, depending on the relative position of the inflection point of the inner cone of the nozzle and the inner wall surface of the movable part of the nozzle inner cylinder, the forward or backward movement of the movable part of the nozzle inner cylinder under the action of the electric actuator may lead to a change in the cross-sectional area of ​​the inner throat that is contrary to the above conclusions. 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 actuator will lead to an increase in the area of ​​the inner throat, while extending the electric actuator will lead to a decrease in the area of ​​the inner throat.

[0047] The second working method:

[0048] The engine operates in rotating detonation ramjet mode. Airflow is ejected through the outer bypass duct of the nozzle of this invention, generating thrust, while the inner bypass duct remains inactive. Specifically, after the engine operates in turbine mode (where the nozzle operates in the first operating mode) for a period of time, the aircraft accelerates to the minimum speed required for rotating detonation ramjet mode operation and switches to rotating detonation ramjet mode to improve engine performance. At this time, the turbine core engine stops, and only the rotating detonation combustion chamber surrounding the core engine operates. Airflow flows through the rotating detonation combustion chamber surrounding the core engine, and after fuel is added, it generates combustion gas through the rotating detonation combustion process and is discharged through the outer bypass duct of the nozzle of this invention. The outer bypass duct is formed by the outer wall of the nozzle casing and the inner cylinder of the nozzle, and is fixed by welding six ribs. The cross-section of the ribs is a flat rhombus shape to suit supersonic airflow. At this time, all airflow flows through the outer bypass duct, and its cross-sectional area change law and profile change law also follow aerodynamic design, following the Laval nozzle design principle of first contraction and then expansion. In actual design, a plug-type nozzle design method can be adopted. At this point, the airflow passing through the nozzle of this invention exhibits both subsonic and supersonic speeds. Specifically, at different circumferential positions, part of the airflow is subsonic, while another part is supersonic. The airflow uniformly changes to sonic speed at the outer throat and accelerates to supersonic speed in the subsequent expansion channel. However, the shape of the outer channel is not fixed and can be altered by moving the movable part of the nozzle inner cylinder using an electric push rod, particularly changing the cross-sectional area of ​​the outer throat—the point where the cross-sectional area of ​​the outer channel is smallest. For example... Figure 5As shown, when the electric push rod is shortened in a controlled manner, the movable part of the nozzle inner cylinder moves forward, and the cross-sectional area of ​​the outer bypass throat increases; when the electric push rod is extended in a controlled manner, the movable part of the nozzle inner cylinder moves backward, and the cross-sectional area of ​​the outer bypass throat decreases. When the aircraft operates at a lower altitude, the ambient pressure is higher, and the outer bypass throat area needs to be increased to increase the engine flow rate and reduce the nozzle expansion ratio in order to reduce the pressure of the rotating detonation combustion chamber and ensure its normal operation, while also matching the pressure of the ejected gas with the ambient pressure. Similarly, when the aircraft operates at a higher altitude, the ambient pressure is lower, and the outer bypass throat area needs to be reduced to decrease the engine flow rate and increase the nozzle expansion ratio in order to increase the pressure of the rotating detonation combustion chamber and ensure its normal operation, while also matching the pressure of the ejected gas with the ambient pressure. It should be noted that, depending on the relative positions of the inflection points of the outer wall surfaces of the nozzle outer casing and the movable parts of the nozzle inner cylinder, the forward or backward movement of the nozzle outer casing under the action of the electric push rod may cause the change in the cross-sectional area of ​​the duct throat to be contrary to the above conclusions. This example is still within the scope of protection of this application. For instance, if the inflection point of the outer wall surface of the duct is before the inflection point of the inner wall surface of the duct, shortening the electric push rod will cause the duct throat area to shrink, while extending the electric push rod will cause the duct throat area to expand.

[0049] This invention provides an adjustable nozzle adapted to the high-frequency time-varying flow field of a rotating detonation combined engine, comprising an inner nozzle cone, an outer nozzle cover, an inner nozzle cylinder, and an electric push rod. The inner nozzle cylinder consists of a movable component and a fixed component. An outer bypass channel is formed between the outer walls of the outer nozzle cover and the inner nozzle cylinder, while an inner bypass channel is formed between the inner wall of the inner nozzle cylinder and the inner nozzle cone. The profile of the outer bypass channel is designed according to the outlet flow field of the rotating detonation engine, and the movable component of the inner nozzle cylinder acts as a movable plug cone for a plug-type nozzle. The axisymmetric annular outer bypass channel matches the annular combustion chamber of the rotating detonation engine, ensuring that the engine achieves high thrust in the rotating detonation mode while the nozzle is adjustable under different operating conditions of the engine in the rotating detonation mode. The adjustment of the outer bypass throat area depends on the electric push rod traction of the movable component of the inner nozzle cylinder, which can slide on the fixed component of the inner nozzle cylinder to adjust the outer bypass throat area. Simultaneously, this adjustment method can also adjust the area of ​​the inner throat. When the combined engine is flying at low altitude and low Mach number in turbine mode, thrust is generated by exhaust from the inner channel. When the combined engine is flying at high altitude and high Mach number in rotating detonation ramjet mode, thrust is generated by exhaust from the outer bypass channel. When the engine is operating in these two modes, the extension of the electric pushrod is adjusted according to the change in the engine's operating environment pressure, thereby adjusting the area of ​​the inner and outer throats. This allows the nozzle operation to match the environmental conditions, improving the heat-to-work conversion efficiency of the rotating detonation ramjet combined engine over a wide speed range.

[0050] The above embodiments are merely preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A variable nozzle adapted to accommodate the high frequency time varying flow field of a rotating detonation combined engine, characterized in that Includes the nozzle inner cone, nozzle inner cylinder, nozzle outer cover, and electric push rod; The nozzle inner cone is disposed in the cavity formed by the nozzle inner cylinder. The nozzle inner cone includes a connecting straight section, an expanding surface section and a contracting surface section arranged in sequence. The connecting straight section is used to be fixedly connected to the inner wall surface of the nozzle inner cylinder fixing member by ribs, supporting the inner flow channel through which the airflow passes under turbine mode. The expanding surface section and the contracting surface section serve as the inner wall surface of the inner flow channel. The nozzle inner cylinder comprises two parts: a fixed part and a movable part, which can slide relative to each other. The nozzle inner cylinder is located in the cavity formed by the nozzle shell and the nozzle outer cover. The outer wall of the fixed part is connected to the nozzle outer cover by ribs, which support the gap between the nozzle inner cylinder and the nozzle outer cover, serving as an outer bypass channel for the airflow under the rotating detonation ramming mode. The outer wall of the movable part is designed according to the flow field characteristics of the rotating detonation combustion chamber outlet, including a connecting straight section, an expanding surface section, and a contracting surface section arranged in sequence, serving as the inner wall of the outer bypass channel. The inner wall of the movable part includes a connecting straight section, a contracting surface section, and an expanding surface section arranged in sequence, serving as the outer wall of the inner bypass channel. The nozzle outer cover includes a connecting straight section and a plug-type nozzle profile section arranged in sequence. The connecting straight section is used to fix the nozzle inner cylinder fixing member with ribs, and the plug-type nozzle profile section serves as the outer wall surface of the outer bypass channel. The two ends of the electric push rod are respectively connected to the nozzle inner cylinder fixing component and the nozzle inner cylinder movable component to pull the relative sliding between the two. The fixed end of the electric push rod is connected to the nozzle inner cylinder fixing component, and the telescopic end of the electric push rod is connected to the nozzle inner cylinder movable component. The nozzle inner cylinder fixing component and the nozzle inner cylinder movable component are slidably connected by ball bearings, the nozzle inner cylinder fixing component and the nozzle outer cover are fixedly connected by ribs, and the nozzle inner cylinder fixing component and the nozzle inner cone are fixedly connected by ribs. The movable part of the nozzle inner cylinder acts as the movable plug cone of the rotating detonation nozzle. It is designed together with the nozzle outer cover according to the plug nozzle principle. The profile of the nozzle outer cover and the nozzle inner cylinder is designed according to the motion law of the oblique shock wave at the rotating detonation outlet, so that the thrust under the rotating detonation stamping mode reaches the optimal value. The expansion and contraction sections of the nozzle inner cone are structured to expand from front to back and then contract, which is used to adjust the flow field characteristics of the inner channel in turbine mode. The expanding and contracting sections of the inner wall of the movable part of the nozzle inner cylinder are structured to contract first and then expand from front to back, which is used to further adjust the flow field characteristics of the inner channel in turbine mode. When the engine is in turbine operating mode, the airflow is ejected through the inner channel of the nozzle to generate thrust, while the outer channel is not working; when the engine is in rotating detonation ramjet mode, the airflow is ejected through the outer channel of the nozzle to generate thrust, while the inner channel is not working.

2. The adjustable nozzle for accommodating the high frequency time varying flow field of a rotary detonation combined engine of claim 1, wherein There are a total of 6 ball grooves between the nozzle inner cylinder fixing component and the nozzle inner cylinder movable component, which are evenly distributed circumferentially. Each ball groove contains 6 balls to provide the smooth sliding required for nozzle adjustment.

3. The adjustable nozzle for adapting to the high-frequency time-varying flow field of a rotary detonation combined engine as described in claim 1, characterized in that... All ribs and side connectors are welded; the six ribs used to support the outer channel are designed as flat rhomboid prisms, that is, the cross-section is flat rhomboid 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 impingement mode.

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