Combustion oscillation suppression structure, suppression method and ramjet engine

Abstract

The invention belongs to the field of ramjet engines, and particularly relates to a combustion oscillation restraining structure and method and a ramjet engine, and the combustion oscillation restraining structure comprises a combustion oscillation forward sensing assembly, a pressure potential energy flow guiding device and a controller; the combustion oscillation forward sensing assembly comprises two pressure sensors arranged between an inlet of the combustion chamber and the injector; the pressure potential energy flow guide device comprises a flow guide pipe and a valve arranged in the flow guide pipe, an inlet of the flow guide pipe communicates with the inner wall of the combustion chamber and is located between the two pressure sensors, and an outlet of the flow guide pipe communicates with the spray pipe; the controller is used for controlling the opening and closing or the opening degree of the valve according to the combustion oscillation condition obtained by the combustion oscillation forward sensing assembly. According to the combustion oscillation suppression structure, combustion oscillation suppression is conducted on the basis of the internal mechanism of combustion oscillation of the ramjet, the pressure potential energy flow guiding device fully utilizes the pressure difference existing in the reaction flow field to adjust the flow field in a self-adaptive mode, and the thermodynamic cycle efficiency cannot be reduced.

Description

Technical Field

[0001] The present invention belongs to the field of ramjet engines, and in particular relates to a combustion oscillation suppression structure, a suppression method and a ramjet engine. Background Art

[0002] Air-breathing ramjets are the most promising propulsion systems for hypersonic cruise vehicles, offering advantages such as a simple structure and no rotating parts. Using the inlet to capture air, fuel is injected separately into the engine's flow field to react with the high-enthalpy airflow. The heat released by combustion within the confined space generates a strong adverse pressure gradient. As the global fuel / air equivalence ratio increases significantly, large-scale separation of the upstream boundary layer occurs, turbulent flames propagate upstream, and even violent combustion oscillations occur, ultimately leading to engine failure.

[0003] Combustion oscillation can lead to unstable operation and even flameout, requiring significant consideration during the engine design phase. To prevent engine misstarts, some researchers have proposed conventional methods for suppressing flow separation, such as optimizing internal flow path profiles and distributed injection (CN117249452A - A Supersonic Combustor and Scramjet Engine for Suppressing Non-Uniform Flow Separation; CN116702646A - A Scramjet Engine Design Method Based on Profile and Heat Release Matching; CN 116971891A - A Wide-Range Scramjet Engine Based on Distributed Fuel Injection). However, the difficulty in adjusting these profiles limits their wide-range application. Others have developed techniques for mitigating combustion oscillations by extracting or injecting inlet air to alter the local flow state of the downstream combustion chamber, a design approach most similar to the present invention. One approach (CN101907042A - A Suction-Type Air-Breathing Engine Combustion Chamber for Eliminating Combustion Oscillations) uses a valve to control the extraction of a small amount of gas from the sudden expansion structure within the combustion chamber. By controlling the timing and amount of the extraction, the reverse vortex in the flow field is destroyed. Similarly, another approach (CN101907038A - A Ramjet Combustion Chamber for Eliminating Combustion Oscillations) injects a small amount of air from the inlet duct into the combustion chamber, continuously injecting it into the rearward step of the combustion chamber to destroy the vortex generated there. Both approaches essentially aim to eliminate large-scale vortices within the combustion chamber, thereby eliminating ramjet combustion oscillations. However, it is important to note that the removal of high-temperature gas from the combustion chamber not only reduces overall engine performance but also presents certain obstacles to the integration of aircraft and engine systems. Taking CN101907038A - A Suction-Type Ramjet Combustion Chamber for Eliminating Combustion Oscillations as an example, this approach injects additional air into the combustion chamber, causing the local equivalence ratio to deviate from its optimal value. In addition, the momentum transfer of the jet flow causes secondary flow field reorganization in the combustion chamber, which enhances viscous dissipation and ultimately leads to a decrease in the thermodynamic cycle efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a combustion oscillation suppression structure, suppression method and ramjet engine that can ensure that the local equivalence ratio in the combustion chamber is always at an optimal value and can maintain the thermodynamic cycle efficiency.

[0005] The present invention provides a combustion oscillation suppression structure, comprising a combustion oscillation front sensing component, a pressure potential energy guide device and a controller; The combustion oscillation front sensing assembly includes two pressure sensors disposed between the combustion chamber inlet and the injector, the two pressure sensors being arranged sequentially from upstream to downstream of the combustion chamber; The pressure potential energy guide device includes a guide pipe and a valve arranged in the guide pipe, the inlet of the guide pipe is connected to the inner wall of the combustion chamber and is located between the two pressure sensors, and the outlet of the guide pipe is connected to the nozzle; The controller is used to control the opening or closing or opening degree of the valve according to the combustion oscillation situation obtained by the combustion oscillation front sensing component. Furthermore, the middle position of the two pressure sensors is located 20% upstream of the combustion chamber.

[0006] Furthermore, the guide pipes and valves are arranged in a circular array along the axis of the combustion chamber. N indivual.

[0007] Furthermore, the number of the guide tubes N and the diameter of a single flow guide tube The flow guide pipe layout model is satisfied, and the flow guide pipe layout model is:

[0008] Where, D is the inlet diameter of the combustion chamber, A is the central cross-sectional area of the combustion chamber.

[0009] Furthermore, the distance between the two pressure sensors is 2 d -3 d .

[0010] Furthermore, the valve is arranged at the upstream end of the flow guide pipe.

[0011] Furthermore, a check valve is provided in the downstream end of the flow guide pipe.

[0012] The present invention also provides a method for suppressing combustion oscillations, using the above-mentioned combustion oscillation suppression structure, comprising the following steps: S1, the controller obtains the values of two pressure sensors, where the value of the pressure sensor near the combustion chamber inlet isP 1, the value of the pressure sensor near the combustion chamber outlet is P 2; S2, the controller P 1 and P 2. Perform analysis: when P 1< P At 2, the controller controls the valve to open or close to a set opening, adjusts the flow channel cross-sectional area of the connected guide pipe, and allows the high-temperature gas at the combustion chamber inlet to pass through the guide pipe into the downstream nozzle, thereby suppressing combustion oscillation; when P 1≥ P 2, the controller controls the valve to close.

[0013] Furthermore, the guide pipe and the valve are arranged in a circular array along the axis of the combustion chamber. N hour; When the controller detects P 2- P 1 is greater than or equal to the set value, the number of valve openings will be increased synchronously, and the valve opening parameters will be increased; on the contrary, when the controller detects that P 2- P When 1 is less than the set value, the number of activated valves to be opened is reduced, and the valve opening parameters are reduced at the same time.

[0014] The present invention also provides a ramjet engine, comprising an air inlet, a combustion chamber and a nozzle arranged in sequence; An injector is provided in the combustion chamber; The ramjet engine also includes the above-mentioned combustion oscillation suppression structure.

[0015] The beneficial effect of the present invention is that the combustion oscillation suppression structure provided by the present invention suppresses combustion oscillation based on the inherent mechanism of the occurrence of combustion oscillation in ramjet engines, and the pressure potential energy guide device fully utilizes the pressure difference existing in the reaction flow field to adaptively adjust the flow field, without causing a decrease in the thermodynamic cycle efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attachment Figure 1 It is a structural schematic diagram of the present invention.

[0017] In the figure, 1-intake duct; 2-combustion chamber; 3-nozzle; 4-injector; 5-pressure sensor; 6-controller; 7-guide tube; 8-valve; 9-check valve. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referenced. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0021] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean mechanical connection, electrical connection, physical connection, or wireless communication connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] As attached Figure 1 As shown, the present invention provides a combustion oscillation suppression structure, including a combustion oscillation front sensing component, a pressure potential energy guide device and a controller 6; The combustion oscillation front sensing assembly includes two pressure sensors 5 disposed between the inlet of the combustion chamber 2 and the injector 4. The two pressure sensors 5 are arranged in sequence from upstream to downstream of the combustion chamber 2. That is, the two pressure sensors 5 are used to detect pressure at two different axial positions on the inlet side of the combustion chamber 2. The pressure potential energy flow guide device includes a flow guide tube 7 and a valve 8 disposed in the flow guide tube 7, wherein the valve 8 controls the opening or closing or opening degree of the flow guide tube 7. The inlet of the flow guide tube 7 is connected to the inner wall of the combustion chamber 2 and is located between the two pressure sensors 5. The outlet of the flow guide tube 7 is connected to the nozzle 3. The flow guide tube 7 is used to introduce the high-temperature combustion gas at the inlet of the combustion chamber 2 into the nozzle 3 during combustion oscillation. The inlet of the flow guide tube 7 is located between the two pressure sensors 5, which can suppress the oscillation of the pressure fluctuation position detected by the combustion oscillation front sensing component. The controller 6 is configured to control the opening and closing, or the degree of opening, of the valve 8 based on the combustion oscillation conditions detected by the combustion oscillation front sensing component. Furthermore, when no combustion oscillation occurs within the combustion chamber 2, the combustion oscillation suppression mechanism is inoperative, and the ramjet operates just like a conventional ramjet. However, when combustion oscillation occurs within the combustion chamber 2, the combustion oscillation suppression mechanism is automatically activated, achieving automated combustion oscillation suppression.

[0024] The combustion oscillation suppression structure provided by the present invention utilizes the inherent mechanism of ramjet combustion oscillation to suppress it. The pressure potential energy flow guide device fully utilizes the inherent pressure differential within the reaction flow field to adaptively adjust the flow field, preventing a decrease in thermodynamic cycle efficiency. Compared to the existing solution (CN101907038A - a jet-based approach to eliminating combustion oscillations in a ramjet combustion chamber) (which injects additional air into the combustion chamber, causing the local equivalence ratio to deviate from its optimal value. Furthermore, the momentum transfer of the jet airflow triggers secondary flow field reorganization in the combustion chamber, enhancing viscous dissipation and ultimately reducing thermodynamic cycle efficiency), the present invention ensures that the local equivalence ratio within the combustion chamber 2 remains optimal and maintains thermodynamic cycle efficiency.

[0025] In one embodiment, considering the constraints of an engine not starting, the combustion oscillation front sensing assembly is positioned as close as possible to the inlet side of the combustion chamber 2. To prevent the influence of the non-uniform flow field in the intake duct 1, the center of the two pressure sensors 5 is located 20% upstream of the combustion chamber 2. Furthermore, the placement of the two pressure sensors 5 upstream of the combustion chamber 2 allows for early capture of oscillation signals, improving response speed.

[0026] In one embodiment, the guide pipe 7 and the valve 8 are arranged in a circular array along the axis of the combustion chamber 2. N This arrangement more effectively covers pressure fluctuations in different directions, as combustion oscillations may propagate as circumferential rotating waves or standing waves. The annular array of flow guides 7 and valves 8 covers 360°, simultaneously intercepting oscillation wave fronts propagating in different angular directions. Furthermore, when the pressure field within combustion chamber 2 is evenly distributed, consistent suppression of combustion oscillations can be achieved throughout combustion chamber 2.

[0027] In a preferred embodiment, the combustion oscillation front sensing components are also arranged in a circular array along the axis of the combustion chamber 2. N , and each group corresponds one-to-one with a flow guide 7. With this arrangement, when the annular array of combustion oscillation front sensing assemblies detects an abnormal pressure distribution within combustion chamber 2, controller 6 selectively opens valves 8 in the corresponding high-pressure areas based on data from the multiple combustion oscillation front sensing assemblies, and thus opens flow guide 7 in the corresponding areas, thus preventing excessive gas loss caused by simultaneous activation of all valves 8. For example, if the oscillation front is located on the left side of combustion chamber 2, valves 8 in the left half of the ring will open first.

[0028] In one embodiment, the number of the flow guide tubes 7 is N and the diameter of a single flow guide tube 7 The flow guide pipe layout model is satisfied, and the flow guide pipe layout model is:

[0029] Where, D is the inlet diameter of combustion chamber 2, A It is the central cross-sectional area of the combustion chamber 2, that is, the central cross-sectional area of the inner flow field.

[0030] In this embodiment, the diameter and number of the flow guide tubes 7 are designed according to the flow guide tube layout model to ensure that when all the flow guide tubes 7 are fully open, the total flow diversion area does not exceed 20% of the internal flow field. In this way, the flow field in the combustion chamber 2 can be significantly changed.

[0031] In one embodiment, the distance between the two pressure sensors 5 is 2 d -3 d Such a setting can prevent the local turbulence at the inlet of the guide tube 7 from affecting the test accuracy of the pressure sensor 5 when the guide tube 7 is opened, thereby ensuring that the pressure sensor 5 can continue to accurately measure pressure throughout the process.

[0032] In one embodiment, the valve 8 is disposed at the upstream end of the flow guide tube 7, thereby minimizing the impact of the flow guide tube 7 on the inner wall of the combustion chamber 2 when combustion oscillation suppression is not required. In a preferred embodiment, the valve 8 includes a valve core that can be inserted into or removed from the inlet opening of the flow guide tube 7 along the axial direction of the combustion chamber 2. In this case, the valve core can be driven by a linear reciprocating drive mechanism. With this arrangement, when the valve 8 is fully closed, the valve core can serve as the inner wall of the combustion chamber 2 without disrupting the internal flow field configuration of the combustion chamber 2. When the valve 8 is open, it only adjusts the opening of the inlet opening of the flow guide tube 7 and does not form a protrusion on the inner wall of the combustion chamber 2, thereby affecting the flow field. In other embodiments, the valve 8 can also be a conventional solenoid valve.

[0033] In one embodiment, in order to prevent the high-temperature gas from flowing back, a check valve 9 is provided in the downstream end of the flow guide pipe 7 .

[0034] The present invention also provides a method for suppressing combustion oscillations, using the above-mentioned combustion oscillation suppression structure, comprising the following steps: S1, the controller 6 obtains the values of the two pressure sensors 5, wherein the value of the pressure sensor 5 near the inlet of the combustion chamber 2 is P 1, the value of the pressure sensor 5 near the outlet of the combustion chamber 2 is P 2; S2, the controller 6 pairs P 1 and P 2. Perform analysis: when P 1< P 2, indicating that the upstream pressure in the combustion chamber 2 is lower than the downstream pressure, indicating that flame backflow occurs in the ramjet engine. The controller 6 controls the valve 8 to open or close to the set opening, and adjusts the flow channel cross-sectional area of the conductive guide pipe 7, so that the high-temperature combustion gas at the inlet of the combustion chamber 2 passes through the guide pipe 7 and enters the downstream nozzle 3, thereby suppressing combustion oscillation. when P 1≥ P 2, indicating that the flame has not been forwarded, the controller 6 controls the valve 8 to close, and the ramjet engine is used in a conventional manner.

[0035] In this embodiment, the control timing is set, if P 1< P 2. Controller 6 outputs a valve 8 open signal, and the high-temperature gas flows through guide pipe 7 into downstream nozzle 3; otherwise, it outputs a valve 8 close signal. It should be noted that valve 8 is closed by default.

[0036] In one embodiment, in order to expand the control capability of the ramjet engine, the guide tube 7 and the valve 8 are arranged in a ring array along the axis of the combustion chamber 2. N At the same time, the working sequence of valve 8 can be further optimized, and the flow rate can be controlled by adopting a multi-stage valve 8 adjustment mechanism. The precise management of the diversion flow can be achieved by adjusting the valve 8 opening parameters and the number of openings and closings. When the controller 6 detects P 2- P 1 is greater than or equal to the set value, that is, when the pressure fluctuation of the combustion chamber 2 is significantly aggravated, the number of valves 8 opened is increased synchronously, and the opening parameter of the valve 8 is increased; on the contrary, when the controller 6 detects that P 2- PWhen 1 is less than the set value, it means that the combustion condition tends to be stable, and the number of valves 8 opened is reduced, and the opening parameter of valve 8 is reduced. This control strategy can effectively match the fluid control requirements under different combustion oscillation intensities and significantly improve the combustion stability control margin. In addition, the combustion oscillation front sensing components are also arranged in a ring array along the axis of the combustion chamber 2. N When the plurality of groups of combustion oscillation front sensing components are used, the controller 6 selectively opens the valve 8 corresponding to the high pressure area to achieve targeted combustion oscillation suppression.

[0037] The present invention also provides a ramjet engine, comprising an air inlet 1, a combustion chamber 2 and a nozzle 3 arranged in sequence; An injector 4 is provided in the combustion chamber 2; The ramjet engine also includes the above-mentioned combustion oscillation suppression structure.

[0038] The above description is merely an embodiment and does not limit the present invention in any way. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make many possible changes, modifications, or modifications to the technical solution of the present invention into equivalent embodiments with equivalent changes using the technical content disclosed above. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A combustion oscillation suppression structure, characterized in that: It includes a combustion oscillation front sensing component, a pressure potential energy guide device and a controller (6); The combustion oscillation front sensing component comprises two pressure sensors (5) arranged between the inlet of the combustion chamber (2) and the injector (4), the two pressure sensors (5) being arranged in sequence from upstream to downstream along the combustion chamber (2); The pressure potential energy flow guide device comprises a flow guide tube (7) and a valve (8) arranged in the flow guide tube (7); the inlet of the flow guide tube (7) is connected to the inner wall of the combustion chamber (2) and is located between the two pressure sensors (5); the outlet of the flow guide tube (7) is connected to the nozzle (3); The controller (6) is used to control the opening and closing or the opening degree of the valve (8) according to the combustion oscillation condition obtained by the combustion oscillation front sensing component.

2. The combustion oscillation suppression structure according to claim 1, wherein: The middle position of the two pressure sensors (5) is located at a position 20% upstream of the combustion chamber (2).

3. The combustion oscillation suppression structure according to claim 1 or 2, wherein: The guide tube (7) and the valve (8) are arranged in a circular array along the axis of the combustion chamber (2). N indivual.

4. The combustion oscillation suppression structure according to claim 2, wherein: The number of the flow guide tubes (7) N and the diameter of a single flow guide tube (7) The flow guide pipe layout model is satisfied, and the flow guide pipe layout model is: Where, D is the inlet diameter of the combustion chamber (2), A is the central cross-sectional area of the combustion chamber (2).

5. The combustion oscillation suppression structure according to claim 4, wherein: The distance between the two pressure sensors (5) is 2 d -3 d .

6. The combustion oscillation suppression structure according to any one of claims 1, 2, 4, and 5, wherein: The valve (8) is arranged at the upstream end of the flow guide pipe (7).

7. The combustion oscillation suppression structure according to claim 6, wherein: A check valve (9) is provided in the downstream end of the flow guide pipe (7).

8. A method for suppressing combustion oscillations, characterized in that: Using the combustion oscillation suppression structure according to any one of claims 1 to 7 comprises the following steps: S1, the controller (6) obtains the values of two pressure sensors (5), wherein the value of the pressure sensor (5) near the inlet of the combustion chamber (2) is P 1, the value of the pressure sensor (5) near the outlet of the combustion chamber (2) is P 2; S2, the controller (6) P 1 and P 2. Perform analysis: when P 1< P At 2, the controller (6) controls the valve (8) to open or close to a set opening, adjusts the flow channel cross-sectional area of the conducting guide pipe (7), and allows the high-temperature combustion gas at the inlet of the combustion chamber (2) to pass through the guide pipe (7) and enter the downstream nozzle (3), thereby suppressing combustion oscillation; when P 1≥ P At 2, the controller (6) controls the valve (8) to close.

9. The combustion oscillation suppression method according to claim 8, wherein The guide tube (7) and the valve (8) are arranged in a circular array along the axis of the combustion chamber (2). N hour; When the controller (6) detects P 2- P 1 is greater than or equal to the set value, the number of valves (8) opened is increased synchronously, and the opening parameter of the valve (8) is increased; on the contrary, when the controller (6) detects P 2- P When 1 is less than the set value, the number of activation valves (8) opened is reduced, and the opening parameter of the valve (8) is reduced at the same time.

10. A ramjet engine, characterized in that: It comprises an air inlet (1), a combustion chamber (2) and a nozzle (3) which are arranged in sequence; An injector (4) is provided in the combustion chamber (2); It also includes the combustion oscillation suppression structure according to any one of claims 1 to 7.

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