Hybrid enhancement device and method for pulse perturbation using plasma excitation

Abstract

The application relates to the technical field of fluid mechanics control, and discloses a mixing enhancement device and method for realizing pulse disturbance by using plasma excitation, which comprises a combustion chamber metal structure, a fuel injection hole arranged at the upstream of the inner cavity of the combustion chamber metal structure, an electrode assembly arranged in the inner cavity of the combustion chamber metal structure, and an electrical switch arranged at the downstream of the combustion chamber metal structure; the electrical switch is electrically connected to the electrode assembly outside the combustion chamber metal structure; fuel is injected into the inner cavity of the combustion chamber metal structure through the fuel injection hole and mixed with airflow, and the electrode assembly is controlled and adjusted through the electrical switch, so that the generation and annihilation of a multi-channel sliding arc plasma discharge region are realized through high frequency, high-frequency pulse disturbance of the flow field is realized, and the mixing of fuel and airflow is enhanced. The synergistic design of the fuel injection hole and the plasma excitation applies high-frequency pulse disturbance to the flow field to enhance fuel mixing, so that the technical problems of heavy structure and poor reliability are solved.

Description

Technical Field

[0001] This invention relates to the field of fluid dynamics control technology, and in particular, to a hybrid enhancement device and method for realizing pulse perturbation using plasma excitation. Background Technology

[0002] In the field of high-speed aerodynamics and propulsion systems, fuel mixing and combustion stability under high-speed airflow conditions are key factors limiting propulsion performance. In high-speed combustion chambers, airflow velocities are extremely high, and fuel residence time is typically on the order of milliseconds. Limited by the compressibility of high Mach number airflows, the shear layer stability within the combustion chamber is strong, resulting in low diffusion mixing efficiency between fuel and oxidizer. Therefore, effectively enhancing fuel-airflow mixing within an extremely short time is a core technical challenge for improving combustion efficiency and propulsion performance.

[0003] In existing technologies, methods for enhancing fuel mixing are mainly divided into two categories: passive enhanced mixing and active enhanced mixing. Passive enhanced mixing technology typically improves mixing efficiency by setting fixed geometric structures (such as supports, ramps, cavities, vortex generators, etc.) inside the combustion chamber or optimizing the arrangement of fuel injection orifices, utilizing aerodynamic characteristics. This type of technology has a simple structure and requires no external energy input, but its mixing enhancement effect is limited by fixed geometric parameters, making it difficult to adjust in real time according to operating conditions, and may introduce significant aerodynamic drag.

[0004] Active mixing enhancement technology involves actively intervening in the flow field or fuel jet during fuel injection to further improve mixing efficiency. Pulse injection is a typical active control technology. Its principle is to control the fuel injection timing, applying periodic disturbances to the flow field at a specific frequency and duty cycle, thereby altering the flow field wave system structure, generating large-scale vortices, and ultimately enhancing fuel diffusion and entrainment. Pulse injection is primarily implemented through two methods: solenoid valve control and mechanical control.

[0005] Solenoid valve control achieves periodic fuel injection by controlling the on / off state of the solenoid valve, offering advantages such as simple system structure and easy-to-implement control logic. However, limited by the response speed of the solenoid valve itself, its injection frequency is typically low (generally in the range of 1Hz to 4Hz), making it difficult to meet the requirements for high-frequency disturbances during the millisecond-level residence time of the high-speed combustion chamber.

[0006] Mechanical control methods (such as rotary injection devices) achieve high-frequency injection through the periodic movement of mechanical structures, with injection frequencies ranging from 1.6 kHz to 10 kHz, which can better match the time scale of high-speed flow fields. However, such devices have problems such as complex structure, large size and weight, easy wear of mechanical parts, and limited reliability. Moreover, when achieving wide-range frequency adjustment, mechanical parts often need to be replaced, resulting in poor flexibility.

[0007] In summary, existing pulse injection solutions have limitations in achieving high-frequency disturbances: solenoid valve solutions have excessively low frequencies, while mechanical solutions are bulky and unreliable. Therefore, there is an urgent need for a fast-responding, compact, reliable, and easily controllable mixing enhancement solution to address the technical challenge of achieving efficient fuel mixing in a very short time under high-speed combustion conditions. Summary of the Invention

[0008] This invention provides a mixing enhancement device and method for pulse perturbation using plasma excitation. By setting a multi-channel sliding arc plasma discharge region downstream of the fuel injection orifice and controlling the generation and annihilation of high-frequency plasma through an electrical switch, high-frequency pulse perturbation is applied to the flow field to enhance fuel mixing. This solves the technical problem that existing pulse injection technology cannot meet the high-frequency perturbation requirements of the combustion chamber within the millisecond-level residence time due to the low frequency of the solenoid valve or the bulky and unreliable structure of the mechanical device.

[0009] According to one aspect of the present invention, a hybrid enhancement device for pulse perturbation using plasma excitation is provided, comprising a combustion chamber metal structure, a fuel injection port provided upstream of the combustion chamber metal structure cavity, and an electrode assembly and an electrical switch provided downstream of the combustion chamber metal structure. The electrode assembly is disposed within the combustion chamber metal structure cavity, and the electrical switch is electrically connected to the electrode assembly from outside the combustion chamber metal structure. Fuel is injected into the combustion chamber metal structure cavity through the fuel injection port and mixed with the airflow. Simultaneously, the electrode assembly is controlled and adjusted by the electrical switch, thereby generating and annihilating a multi-channel sliding arc plasma discharge region at a high frequency, achieving high-frequency pulse perturbation of the flow field, and enhancing the mixing of fuel and airflow.

[0010] Furthermore, multiple fuel injection holes are arranged in a linear array, which is perpendicular to the airflow direction.

[0011] Furthermore, the fuel injection holes are arranged at an angle to the airflow direction, and the fuel injected from the fuel injection holes is injected into the airflow and flows downstream with the airflow.

[0012] Furthermore, the electrode assembly includes an electrode cathode, an electrode anode, and an insulating bushing. The electrode cathode and / or electrode anode are connected and fixed to the inner wall of the combustion chamber metal structure via the insulating bushing. When energized, the electrode anode generates an electric arc that flows into the electrode cathode.

[0013] Furthermore, the cathode and anode electrodes are arranged alternately and spaced apart on the same straight line.

[0014] Furthermore, the arrangement of the cathode and anode electrodes is perpendicular to the airflow direction.

[0015] Furthermore, a recessed cavity device is provided on the wall surface of the combustion chamber metal structure cavity downstream of the electrode assembly. The recessed cavity device is used to increase the mixing of fuel and airflow and stabilize combustion.

[0016] Furthermore, the cavity device adopts a front step device or a rear step device.

[0017] According to another aspect of the present invention, a hybrid enhancement method for pulse perturbation using plasma excitation is also provided. The hybrid enhancement device for pulse perturbation using plasma excitation described above includes the following steps: using electrical control to realize the periodic switching of energization and de-energization of electrode components to generate sliding arc plasma; using the effect of sliding arc plasma on the flow field to induce periodic generation of plasma-induced oblique shock waves, thereby realizing pulse perturbation of the downstream flow field of fuel injection and promoting fuel mixing.

[0018] Furthermore, the method has two injection states: conventional injection and plasma-induced injection. In the conventional injection state, the electrode assembly is not energized and no sliding arc plasma is generated. This injection state is the conventional flat plate injection. After fuel injection, it enters the downstream cavity shear layer and mixes with the mainstream and recirculation zone as the shear layer rolls up. In the plasma-induced injection state, the electrode assembly is energized, generating sliding arc plasma between the electrode anode and electrode cathode. The high temperature effect of the sliding arc causes the gas in the affected area to expand, producing a physical ramp-like effect. An oblique shock wave is generated at the front of the plasma. When the fuel trajectory passes through the plasma-induced oblique shock wave with the gas flow, it will deflect away from the wall, thereby increasing the height of fuel diffusion and thus improving fuel distribution.

[0019] The present invention has the following beneficial effects:

[0020] 1. High-frequency pulse disturbance is achieved, effectively matching the high-speed combustion time scale: By controlling the electrode components through electrical switches, the generation and annihilation of multi-channel sliding arc plasma discharge regions can be achieved at high frequencies (kHz level). This high-frequency characteristic enables the device to generate pulse disturbances that match the millisecond-level fuel residence time in the high-speed combustion chamber, overcoming the defect of existing electromagnetic valve pulse injection that cannot effectively intervene in the flow field due to its low frequency (usually Hz level).

[0021] 2. Enhanced fuel mixing through plasma-induced flow field changes: Under plasma-excited injection conditions, the high-temperature effect generated by the sliding arc discharge causes local gas expansion, creating a physical ramp-like effect in the flow field and inducing oblique shock waves. When the fuel jet flows through this region, its trajectory is deflected, increasing the fuel penetration depth and diffusion range in the flow field. By periodically generating and disappearing this physical effect, high-frequency pulse perturbation is applied to the downstream flow field of the fuel. Utilizing the mechanism that pulse perturbation can excite large-scale vortex structures and enhance fluid entrainment and diffusion, the mixing efficiency of fuel and gas flow is significantly improved.

[0022] 3. Simple structure, flexible control and high reliability: Relying on electrical switch control and electrode assembly discharge, there is no need for complex mechanical moving parts (such as rotating mechanisms), avoiding the problems of bulky structure, easy wear and inconvenient adjustment of mechanical pulse injection devices; the frequency and pulse width of pulse disturbance can be flexibly changed by adjusting the electrical control signal, with low adjustment cost, fast system response speed, and the life and reliability of electronic components are better than those of mechanical parts.

[0023] 4. Facilitates integration with other plasma technologies and enhances overall system performance: Based on plasma excitation, it can share hardware facilities (such as electrode components) with plasma-assisted ignition and plasma flame stabilization. Pulse perturbation-enhanced mixing can be achieved simply by adjusting the control strategy, which is beneficial to improving the overall performance of the combustion system in terms of ignition, flame stabilization and mixing. It has good technical integration and engineering application prospects.

[0024] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 This is a schematic diagram of the structure of a hybrid enhancement device for pulse perturbation using plasma excitation, according to a preferred embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of conventional injection mixing according to a preferred embodiment of the present invention;

[0028] Figure 3 This is a typical flow field velocity cloud diagram (simulation result) under conventional injection in a preferred embodiment of the present invention.

[0029] Figure 4This is a diagram of the morphology of a sliding arc plasma in a high-speed gas flow under electrode energized conditions, according to a preferred embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the jet mixing state under sliding arc plasma excitation according to a preferred embodiment of the present invention;

[0031] Figure 6 This is a velocity cloud diagram (simulation result) of the jet mixing state flow field under sliding arc plasma excitation according to a preferred embodiment of the present invention.

[0032] Legend:

[0033] 1. Fuel injection orifice; 2. Insulating bushing; 3. Electrode cathode; 4. Electrode anode; 5. Cavity device; 6. Combustion chamber metal structure; 7. Cable at the rear end of the electrode; 10. Airflow direction; 20. Bow-shaped shock wave; 30. Fuel trajectory; 40. Cavity leading edge shock wave; 50. Cavity shear layer; 60. Sliding arc plasma; 70. Plasma-induced oblique shock wave; 80. High-temperature plasma region. Detailed Implementation

[0034] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0035] like Figure 1As shown, this embodiment of the hybrid enhancement device for pulse perturbation using plasma excitation includes a combustion chamber metal structure 6. A fuel injection port 1 is located upstream of the combustion chamber metal structure 6, and an electrode assembly and an electrical switch are located downstream of the combustion chamber metal structure 6. The electrode assembly is located within the combustion chamber metal structure 6, and the electrical switch is electrically connected to the electrode assembly from outside the combustion chamber metal structure 6. Fuel is injected into the combustion chamber metal structure 6 through the fuel injection port 1 and mixed with the airflow. Simultaneously, the electrical switch controls and adjusts the electrode assembly, thereby generating and annihilating a multi-channel sliding arc plasma discharge region at a high frequency, achieving high-frequency pulse perturbation of the flow field and enhancing the mixing of fuel and airflow. This invention utilizes a plasma excitation-based hybrid enhancement device for pulse perturbation. Through the control of the electrode assembly by the electrical switch, it can achieve the generation and annihilation of a multi-channel sliding arc plasma discharge region at a high frequency (kHz level). This high-frequency characteristic allows the device to generate pulse perturbations that match the millisecond-level fuel residence time in a high-speed combustion chamber, overcoming the shortcomings of existing electromagnetic valve-type pulse injection systems, which cannot effectively intervene in the flow field due to excessively low frequencies (typically Hz levels). Under plasma-excited injection conditions, the high-temperature effect generated by the sliding arc discharge causes local gas expansion, creating a slope-like effect in the flow field and inducing oblique shock waves. As the fuel jet flows through this region, its trajectory deflects, increasing the fuel's penetration depth and diffusion range within the flow field. Through the periodic generation and dissipation of this physical effect, high-frequency pulse perturbations are applied to the downstream flow field. Utilizing the mechanism that pulse perturbations can excite large-scale vortex structures and enhance fluid entrainment and diffusion, the mixing efficiency of the fuel and gas flow is significantly improved. Relying on electrical switch control and electrode assembly discharge, complex mechanical moving parts (such as rotating mechanisms) are eliminated, avoiding the problems of bulky structure, easy wear, and inconvenient adjustment inherent in mechanical pulse injection devices. The frequency and pulse width of the pulse perturbation can be flexibly changed by adjusting the electrical control signal, resulting in low adjustment costs, fast system response, and superior lifespan and reliability of electronic components compared to mechanical parts. Based on plasma excitation, this device can share hardware facilities (such as electrode components) with plasma-assisted ignition and plasma flame stabilization. It only requires adjustments to the control strategy to achieve pulse perturbation-enhanced mixing, which is beneficial for improving the overall performance of the combustion system in ignition, flame stabilization, and mixing. It has good technological integration and engineering application prospects. This invention utilizes a plasma-excited pulse perturbation mixing enhancement device, achieving high-frequency pulse perturbation through electrical control. It provides a fuel mixing enhancement method with fast response, compact structure, flexible control, and high reliability, effectively solving the problem of improving combustion efficiency caused by extremely short fuel residence time and high mixing difficulty in high-speed combustion environments. Optionally, the electrode component is connected to an electrical switch outside the combustion chamber metal structure 6 via a cable 7 at the rear end of the electrode. Optionally, the cable 7 at the rear end of the electrode is used to connect the electrode component to electrical equipment such as a power supply and a switch.

[0036] In this embodiment, multiple fuel injection holes 1 are arranged in a linear array, perpendicular to the airflow direction. This linear array arrangement allows for a wider initial coverage area of ​​the fuel across a cross-section perpendicular to the airflow direction. Compared to a single nozzle or nozzles arranged in the same direction as the airflow, this vertically arranged array creates a large contact surface with the high-speed airflow in the initial stage of fuel injection into the combustion chamber, providing more favorable starting conditions for subsequent diffusion mixing. Because the linear array is perpendicular to the high-speed airflow direction, the fuel jet ejected from each nozzle forms a transverse shear layer with the mainstream. This transverse shearing helps to rapidly generate vortex structures downstream of the nozzles. The entrainment and stretching effects of these vortices accelerate the mixing process between the fuel and the surrounding air, thereby creating multiple interacting mixing regions in the flow field and improving overall mixing efficiency. Multiple fuel injection orifices 1 are uniformly arranged in an array. Combined with the global pulse disturbance generated by plasma excitation, this helps to achieve a more uniform fuel distribution across the width of the combustion chamber. This reduces localized over-rich (rich fuel) or under-rich (lean fuel) phenomena caused by a single injection position or uneven distribution, thus improving combustion stability and efficiency. The fuel injection orifices 1 are arranged in a linear array perpendicular to the airflow. Working synergistically with the high-frequency pulse disturbance generated by plasma excitation, this further optimizes the fuel-airflow mixing process from three aspects: expanding the initial contact area, enhancing transverse shear mixing, and achieving uniform distribution.

[0037] In this embodiment, the fuel injection orifice 1 is arranged at an angle to the airflow direction. The fuel injected through the fuel injection orifice 1 is injected into the airflow and flows downstream with the airflow. By setting the fuel injection orifice 1 at a certain angle to the airflow direction, when the fuel jet is injected into the high-speed airflow, the component of its axial momentum perpendicular to the airflow direction can overcome the airflow resistance. This momentum exchange allows the fuel jet to penetrate towards the central region of the combustion chamber or the opposite side wall, thereby increasing the fuel distribution height (i.e., penetration depth) in the flow field and preventing the fuel from accumulating only near the wall, which is beneficial for the fuel to fully contact the mainstream air. The fuel jet cuts into the high-speed airflow at a certain angle, forming a strong velocity gradient at the interface between the jet and the mainstream, producing a significant shear effect. This shear effect is the direct driving force for the generation of large-scale vortex structures (such as horseshoe vortices, flow vortices, etc.). The entrainment and stretching effects of the vortex structure can quickly entrain the surrounding air into the fuel jet and promote the diffusion of fuel to the surroundings, thereby accelerating the mixing process. Compared to injection along the airflow direction, injection at a certain angle allows the fuel jet to undergo a longer mixing path perpendicular to the airflow direction while flowing downstream. This three-dimensional mixing path effectively increases the contact time between fuel and air, achieving more thorough mixing within the limited length of the combustion chamber and creating favorable conditions for subsequent combustion reactions. The fuel injection orifice 1 is arranged at an angle to the airflow direction, further improving the mixing efficiency of fuel and airflow by enhancing fuel penetration depth, strengthening shear vortex generation, and extending effective mixing time.

[0038] In this embodiment, the electrode assembly includes an electrode cathode 3, an electrode anode 4, and an insulating bushing 2. The electrode cathode 3 and / or electrode anode 4 are connected and fixed to the inner wall of the combustion chamber metal structure 6 via the insulating bushing 2. When energized, the electrode anode 4 generates an electric arc that flows into the electrode cathode 3. By fixing the electrode cathode 3 and electrode anode 4 to the wall of the combustion chamber metal structure 6 through the insulating bushing 2, reliable electrical isolation between the electrode and the combustion chamber metal shell is ensured, effectively preventing high-voltage discharge current leakage to the main structure of the combustion chamber, avoiding the risk of short circuit, and ensuring the long-term safe and stable operation of the device under high temperature, high pressure, and high-speed airflow environment. The electrode anode 4 and electrode cathode 3 maintain a relatively fixed gap under the positioning of the insulating bushing 2, and a stable electric arc channel can be formed in this gap after energization. The electric arc slides along the electrode surface under the blowing of the high-speed airflow (i.e., sliding arc discharge), thereby generating a continuous and stable plasma in a specific area, providing a basis for applying effective thermal and chemical effects to the flow field. The electrode assembly is positioned downstream of the fuel injection orifice 1, and its fixed position is designed to ensure that the generated sliding arc plasma is located in the critical mixing region of the fuel jet. This arrangement allows the plasma-induced shock wave and high-temperature expansion effect to directly act on the fuel jet, altering its trajectory and enhancing its mixing with the surrounding airflow, thus achieving close coordination between the electrode discharge and fuel mixing processes. The electrode assembly employs a fixed structure including an insulating bushing 2, ensuring stable generation of sliding arc plasma while maintaining electrical safety and structural stability. Furthermore, by optimizing the electrode position, the plasma excitation can be precisely applied to the critical region of fuel mixing. Optionally, the insulating bushing 2 is a ceramic bushing.

[0039] In this embodiment, the cathode 3 and anode 4 are arranged alternately and intermittently along the same straight line. This alternating arrangement of cathodes 3 and anodes 4 allows for the formation of multiple independent discharge channels between adjacent cathodes 3 and anodes 4 after energization. This "cathode-anode-cathode-anode…" alternating arrangement creates a series of linearly distributed plasma discharge regions along the width of the combustion chamber, thereby perturbing the flow field over a larger spatial area, avoiding localized effects caused by a single discharge point, and improving the overall coverage of the enhanced mixing. Because the discharge points are uniformly distributed along a straight line, the thermal and shock wave effects generated by the plasma also tend to homogenize the flow field. This uniformly distributed perturbation helps the fuel achieve more uniform diffusion and mixing across the cross-section of the combustion chamber, reducing mixing dead zones and improving combustion stability and efficiency. The alternating arrangement of cathode and anode on the same straight line results in a more regular electric field distribution between adjacent discharge channels, reducing electric field distortion. This optimized electric field distribution helps maintain the stability of the sliding arc discharge in each channel, ensuring that each discharge point can generate effective and continuous plasma excitation, thereby guaranteeing the reliability of the overall pulse perturbation effect. The cathode 3 and anode 4 are arranged alternately on the same straight line, forming a multi-channel, uniformly distributed plasma discharge region, which expands the flow field perturbation range, improves mixing uniformity, and optimizes discharge stability, thus achieving efficient and reliable mixing enhancement.

[0040] In this embodiment, the arrangement of the cathode 3 and anode 4 is perpendicular to the airflow direction. Setting the straight line formed by the alternating arrangement of the cathode 3 and anode 4 perpendicular to the high-speed airflow direction ensures that the plasma excitation region generated by multiple discharge channels covers the entire width of the combustion chamber cross-section. This ensures that the disturbance effect on the flow field is uniformly distributed across the width of the combustion chamber, thereby enabling comprehensive and thorough intervention in the lateral diffusion process of the fuel jet, effectively improving the overall mixing integrity of fuel and airflow across the entire cross-section of the combustion chamber. The fuel injection orifices 1 are also arranged in a linear array perpendicular to the airflow direction; the electrode arrangement is perpendicular to the airflow direction, ensuring that the disturbance wavefront generated by plasma excitation remains parallel to the initial jet distribution surface formed by fuel injection. This geometrical matching relationship facilitates the maximum spatial interaction between plasma-induced shock waves, high-temperature expansion effects, etc., and the fuel jet, thereby more effectively changing the fuel trajectory, exciting vortex structures, and enhancing the mixing effect. If the electrode assembly is arranged along the airflow direction, the plasma excitation generated by the downstream electrode may be affected by the already disturbed flow field upstream, causing the disturbance effect to gradually decrease along the flow direction. However, the vertical arrangement ensures that the disturbances generated by all electrodes act on the same flow direction position almost simultaneously, avoiding the disturbance intensity loss that may occur with the forward arrangement, and ensuring that the strongest pulse disturbance can be applied at the key position downstream of the fuel injection. The arrangement of the cathode 3 and anode 4 is perpendicular to the airflow direction. By coordinating with the arrangement of the fuel injection hole 1, uniform disturbance is achieved across the entire width of the combustion chamber, avoiding disturbance attenuation and ensuring efficient and uniform mixing across the entire width of the combustion chamber.

[0041] In this embodiment, a recessed cavity device 5 is formed on the wall downstream of the electrode assembly within the combustion chamber metal structure 6. The recessed cavity device 5 is used to increase the mixing of fuel and airflow and stabilize combustion. The recessed cavity device 5 forms a certain geometric volume downstream of the electrode assembly. When the high-speed airflow flows through the cavity opening, a stable low-speed recirculation zone is formed inside the cavity. This recirculation zone can capture some fuel and burned particles, allowing them to circulate and mix within the cavity for a longer period. This mechanical passive mixing mechanism complements the active plasma pulse disturbance generated by the upstream electrode assembly, further enhancing the mixing process of fuel and airflow in both spatial and temporal dimensions. The recirculation zone formed by the recessed cavity device 5 can serve as a stable ignition source and flame maintainer. The burned particles within the recirculation zone have a high temperature, which can continuously ignite the newly entering fuel-air mixture, thereby effectively stabilizing the flame, preventing flameout under the high strain rate of the high-speed airflow, and improving the combustion stability of the combustion chamber. The concave cavity device 5 is located downstream of the electrode assembly, allowing the pulsed disturbances (such as shock waves and high-temperature jets) generated by plasma excitation to directly act on the shear layer upstream of the cavity, altering its stability and promoting the entrainment of fuel jets into the cavity. Simultaneously, the cavity provides a favorable flow field environment for plasma-assisted ignition and flame stabilization, enabling plasma technology and cavity flame stabilization technology to work synergistically, forming a composite hybrid enhancement and combustion stabilization mechanism of "active pulsed disturbance + passive cavity flame stabilization." By placing the concave cavity device 5 downstream of the electrode assembly, a stable recirculation zone is formed, further enhancing fuel mixing and stabilizing the combustion process. Furthermore, it achieves a good synergistic effect with the upstream plasma pulsed disturbance technology, thereby realizing efficient and stable combustion.

[0042] In this embodiment, the cavity device 5 employs either a front-step device or a rear-step device. Whether it's a front-step device (with a protrusion on the upstream wall of the cavity) or a rear-step device (with a protrusion on the downstream wall of the cavity), its step structure induces flow separation in the high-speed airflow. This separated flow forms a shear layer above the cavity and induces a stable recirculation zone inside the cavity. This recirculation zone effectively entrains and retains the fuel-air mixture, providing a longer residence time for mixing and combustion, thereby enhancing the mixing effect and stabilizing combustion. The front-step and rear-step devices differ in their flow field structure. The front-step device primarily induces flow separation through the upstream protrusion, and its shear layer is closer to the upstream of the cavity, which is beneficial for the rapid entrainment of fuel injected upstream. The rear-step device, on the other hand, induces separation through the downstream protrusion, and its shear layer structure helps stabilize the flow field behind the cavity. By selecting a front-step or rear-step structure, the flame stabilization performance of the cavity can be optimized according to the specific flow field characteristics of the combustion chamber (such as mainstream velocity, fuel injection position, etc.), making it better adaptable to different operating conditions. The concave cavity device 5 is located downstream of the electrode assembly. The periodic pulse perturbations (such as shock waves and high-temperature jets) generated by plasma excitation can directly act on the shear layer generated by the step device. This perturbation can change the stability of the shear layer, stimulate the generation and development of vortex structures, thereby promoting the entrainment of fuel into the concave cavity and enhancing fuel mixing in and downstream of the concave cavity. At the same time, the stable recirculation zone provided by the concave cavity also provides favorable conditions for plasma-assisted ignition and flame stabilization, forming a synergistic enhancement mechanism of plasma pulse perturbation and stepped concave cavity flame stabilization. The concave cavity device 5 adopts a front-step or rear-step structure, which utilizes the flow separation generated by the steps to form a stable shear layer and recirculation zone, and works synergistically with the upstream plasma pulse perturbation technology to further enhance the fuel mixing effect and combustion stability.

[0043] This embodiment utilizes a plasma-excited method for hybrid enhancement of pulsed perturbations, employing the aforementioned plasma-excited device for hybrid enhancement of pulsed perturbations. The method includes the following steps: using electrical control to periodically switch the energization and de-energization of the electrode assembly, generating a sliding arc plasma; utilizing the effect of the sliding arc plasma on the flow field, causing the plasma to induce periodic generation of oblique shock waves, thereby creating pulsed perturbations in the downstream flow field of fuel injection and promoting fuel mixing. The method uses electrical switch control to periodically switch the energization and de-energization of the electrode assembly, thus controlling the periodic generation and annihilation of the sliding arc plasma. Due to the extremely fast response speed of the electrical control (up to the microsecond level), this method can achieve high-frequency pulsed perturbations in the kHz range, effectively overcoming the shortcomings of existing electromagnetic valve-type pulsed injection frequencies that are too low (Hz level). This allows the period of the pulsed perturbation to match the millisecond-level residence time of the fuel in the high-speed combustion chamber, thus effectively intervening in the flow field within a limited time. During the energizing phase, the electrode assembly generates a sliding arc plasma. Its high-temperature effect causes localized gas expansion, creating a slope-like effect in the flow field and inducing a sloping shock wave. As the fuel jet flows through this region, its trajectory deflects, increasing its penetration depth. During the de-energizing phase, the plasma annihilates, the shock wave disappears, and the flow field recovers. Through this periodic generation and dissipation of physical effects, a high-frequency pulse disturbance is applied to the downstream flow field of the fuel. Utilizing the mechanism that pulse disturbance can excite large-scale vortex structures and enhance fluid entrainment and diffusion, the mixing efficiency of the fuel and gas flow is significantly improved. The method primarily relies on the adjustment of electrical control signals to control the frequency and pulse width of the pulse disturbance, without requiring changes to the mechanical structure. This allows for flexible adjustment at minimal cost. Furthermore, the method can share hardware facilities such as the electrode assembly with existing technologies such as plasma-assisted ignition and flame stabilization. Enhanced mixing through pulse disturbance can be achieved simply by adjusting the control strategy, demonstrating good technological integration and engineering application prospects. The method of this invention realizes high-frequency pulse perturbation of plasma excitation through electrical control, and provides a fuel mixing enhancement method with fast response speed, flexible control and high reliability. It effectively solves the problem of improving combustion efficiency caused by the extremely short fuel residence time and the difficulty of mixing in high-speed combustion environment.

[0044] In this embodiment, the method has two injection states: conventional injection and plasma-induced injection. In the conventional injection state, the electrode assembly is not energized and no sliding arc plasma is generated. This injection state is the conventional flat plate injection. After fuel injection, it enters the downstream concave cavity shear layer and mixes with the mainstream and recirculation zone as the shear layer rolls up. In the plasma-induced injection state, the electrode assembly is energized, and a sliding arc plasma is generated between the electrode anode 4 and the electrode cathode 3. The high temperature effect of the sliding arc causes the gas in the affected area to expand, generating a physical ramp-like effect. An oblique shock wave is generated at the front of the plasma. When the fuel trajectory passes through the plasma-induced oblique shock wave with the airflow, it will deflect away from the wall, thereby increasing the height of fuel diffusion and thus improving fuel distribution. By controlling the energization and de-energization of the electrode assembly, the method can switch between conventional injection and plasma-excited injection states. The conventional injection state provides a basic, continuous mixing process, ensuring a fundamental mixing effect of the fuel without additional intervention. The plasma-excited injection state, on the other hand, provides active and enhanced mixing intervention. These two states can be selected or combined according to the actual operating conditions of the combustion chamber (such as different flight Mach numbers, equivalence ratios, etc.), enhancing the device's adaptability to different operating conditions. In the plasma-excited injection state, the sliding arc plasma generated by energization utilizes its high-temperature effect to cause local gas expansion, producing a physical ramp-like effect and inducing a sloping shock wave at its front. This physical effect forces the fuel jet trajectory to deflect away from the wall, significantly increasing the fuel penetration depth (i.e., diffusion height), thereby improving the uniformity of fuel distribution across the combustion chamber cross-section and preventing fuel from accumulating only near the wall, creating favorable conditions for complete combustion. In conventional injection mode, the fuel jet enters the downstream concave cavity shear layer, where it undergoes initial mixing with the mainstream and recirculation zones through the entrainment effect of the shear layer. In plasma-excited injection mode, this mixing process is further enhanced by the periodically applied plasma effect. This combination of conventional and active intervention, working at different levels (continuous mixing and pulsed perturbation, near the wall and in the central region), optimizes the fuel mixing effect. This invention provides a mixing mode that combines basic and enhanced approaches by setting two injection states: conventional and plasma-excited. It significantly improves fuel distribution by utilizing the unique physical effects of the plasma-excited state, and works synergistically with the conventional state, thereby achieving multi-dimensional optimization of the fuel mixing process and effectively improving mixing efficiency and combustion performance.

[0045] During implementation, a hybrid enhancement scheme using plasma excitation to achieve pulse perturbation was proposed. The multi-channel sliding arc plasma discharge region was set downstream of the fuel injection orifice. Through electrical switch control, the generation and annihilation of the multi-channel sliding arc plasma discharge region were achieved at high frequency, thereby realizing high-frequency pulse perturbation of the flow field and enhancing fuel mixing. This scheme has low weight and volume costs, and high-frequency control can be achieved solely through electrical switch control, showing good application prospects.

[0046] The working principle of the hybrid enhancement device that uses plasma excitation to achieve pulse perturbation: The device operates in two states: conventional injection and plasma-excited injection.

[0047] In conventional injection mode: the electrodes are not energized, and no sliding arc plasma is generated. This injection mode is equivalent to conventional flat-plate injection. After fuel injection, it enters the downstream concave cavity shear layer 50. The coiled portion of the concave cavity shear layer 50 mixes with the mainstream and recirculation regions. Figure 2 This is a schematic diagram illustrating the principle of conventional injection; specifically, Figure 2 The flow characteristics of the airflow along the flow direction (airflow direction 10) through the conventional injection area are shown. The airflow first encounters the fuel injection hole, and the fuel is injected into the mainstream to form a mixing region and form an arc-shaped shock wave 20. The fuel trajectory 30 continues to flow downstream with the mainstream and encounters the front edge of the cavity, generating a front edge shock wave 40. At the same time, a cavity shear layer 50 is formed above the cavity. This cavity shear layer 50 separates the mainstream from the backflow region inside the cavity, forming a typical shock wave-shear layer-cavity coupled flow structure. Figure 3 The results are from a flow field simulation of a conventional injection. Figure 3 The cloud map shows that the fluid velocity decreases from left to right within the flow channel. The left region is red and orange, corresponding to the high-speed flow region, while the right region gradually transitions to blue and green, corresponding to the low-speed region. The distribution of velocity contour lines is clearly visible within the flow field. The overall velocity field distribution pattern conforms to the basic physical characteristics of fluid shear layer development and velocity decay under conventional jetting conditions, providing a comparative benchmark for subsequent flow field changes in plasma-excited jetting.

[0048] Plasma-excited jet state: The electrodes are energized, generating a sliding arc plasma 60 between the anode and cathode, such as... Figure 4 As shown, the high-temperature effect of the sliding arc plasma 60 causes the gas in the affected area to expand, creating a physical ramp-like effect and generating an oblique shock wave in the plasma front. When the fuel trajectory 30 passes through the plasma-induced oblique shock wave 70 with the airflow (airflow direction 10), it will deflect away from the wall, thereby increasing the height of fuel diffusion (i.e., penetration depth), which is beneficial to improving fuel distribution. Figure 5This is a schematic diagram illustrating the principle of plasma-excited jet mixing. When the gas flow passes through the plasma-excited jet region along the flow direction (flow direction 10), it is affected by the sliding arc plasma 60 generated by the electrode energization. Due to the high temperature effect, the gas in the affected area (high temperature plasma region 80) of the sliding arc plasma 60 expands, producing an effect similar to a physical ramp, forming a plasma-induced oblique shock wave 70 at the front of the plasma. When the fuel trajectory 30 passes through the plasma-induced oblique shock wave 70 with the gas flow, it deflects away from the wall, thereby increasing the height of fuel diffusion (i.e., penetration depth), which is beneficial to improving fuel distribution. At the same time, the sliding arc plasma 60 itself... Figure 4 It appears as a bright, periodic arc shape, and its presence is accompanied by the formation of a high-temperature plasma region 80, which as a whole reflects the flow control mechanism of jet mixing under plasma excitation. Figure 6 The results are from a flow field simulation of a conventional injection. Figure 6 The cloud map shows that under the influence of plasma, the velocity distribution of the flow field exhibits significant spatial differences. The left region is dominated by red and orange, corresponding to the high-speed zone, with a velocity peak (approximately 1395 units) visible at the core, accompanied by a clear distribution of high-speed contour lines. The velocity in the middle and right regions gradually transitions to green and blue, indicating a significant velocity decay. Meanwhile, the black streamlines reveal a complex flow structure, including flow direction deflection and possible downstream vortex characteristics. Overall, this reflects that plasma excitation effectively promotes the mixing of fuel jets with air and energy distribution by inducing shock waves and altering the local flow field.

[0049] Pulse-induced perturbation-enhanced mixing mechanism: By utilizing electrical control to achieve periodic switching of electrode energization and de-energization, the effect of sliding arc plasma on the flow field can be leveraged to induce periodic oblique shock waves, thereby creating pulse perturbations in the downstream flow field of fuel injection and promoting fuel mixing. According to the pulse injection mixing enhancement mechanism, the mixing effect under pulse injection and flow field pulse perturbation is stronger than that under continuous injection, and a superior mixing enhancement effect can be obtained under appropriate period and bandwidth.

[0050] The advantages of a hybrid enhancement device that utilizes plasma excitation to achieve pulse perturbation:

[0051] (1) Compared with continuous conventional injection and stable plasma-excited injection, the fuel mixing effect under pulse perturbation is better, which is a promising and effective fuel mixing enhancement technology.

[0052] (2) The solution can control and adjust the frequency and bandwidth of the pulse disturbance through electrical control, with low adjustment cost and no additional burden on weight or space. At the same time, the electrical control can achieve higher frequencies (in the kHz range), has a long component life, and has good prospects for engineering applications;

[0053] (3) The scheme can be integrated with plasma-assisted ignition, plasma flame stabilization, plasma mixing enhancement and other technical schemes. Without changing the hardware facilities, pulse disturbance can be achieved by adjusting the control strategy, which can further enhance the mixing of fuel and effectively improve the effect of plasma-enhanced mixing and assisted combustion.

[0054] Matters not covered in this invention are common knowledge.

[0055] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hybrid enhancement device for pulsed perturbation using plasma excitation, comprising a combustion chamber metal structure (6), characterized in that, The combustion chamber metal structure (6) has a fuel injection hole (1) upstream of its inner cavity and an electrode assembly and an electrical switch downstream of its inner cavity. The electrode assembly is located in the inner cavity of the combustion chamber metal structure (6) and the electrical switch is connected to the electrode assembly from the outside of the combustion chamber metal structure (6). Multiple fuel injection holes (1) are arranged in a linear array. The linear array is arranged perpendicular to the airflow direction, and the fuel injection holes (1) are arranged at an angle to the airflow direction. The fuel injected by the fuel injection holes (1) is injected into the airflow and flows downstream with the airflow. The multiple fuel injection holes (1) are evenly arranged in an array. With the global pulse disturbance generated by plasma excitation, it helps to achieve a more uniform distribution of fuel in the width direction of the combustion chamber and reduces the phenomenon of local fuel being too rich or too lean due to a single injection position or uneven distribution. The electrode assembly includes an electrode cathode (3), an electrode anode (4), and an insulating bushing (2). The electrode cathode (3) and / or electrode anode (4) are connected and fixed to the inner wall of the combustion chamber metal structure (6) via the insulating bushing (2), ensuring reliable electrical isolation between the electrode and the combustion chamber metal shell, preventing high-voltage discharge current from leaking into the main structure of the combustion chamber, avoiding short-circuit risks, and ensuring long-term safe and stable operation of the device under high temperature, high pressure, and high-speed airflow environments. After being energized, the electrode anode (4) generates an electric arc that flows into the electrode cathode (3), forming multiple arcs between adjacent electrode cathodes (3) and electrode anodes (4). Each independent discharge channel forms a series of plasma discharge regions distributed along a straight line in the width direction of the combustion chamber; the electrode cathode (3) and electrode anode (4) are arranged alternately and spaced on the same straight line; the arrangement of the electrode cathode (3) and electrode anode (4) is perpendicular to the airflow direction, so that the plasma excitation region generated by multiple discharge channels can cover the entire width direction of the combustion chamber cross section, ensuring that the disturbance effect on the flow field is evenly distributed in the width of the combustion chamber, and the disturbance generated by all electrodes acts on the same flow direction position almost simultaneously, avoiding the possible loss of disturbance intensity caused by the unidirectional arrangement; A concave cavity device (5) is provided on the wall of the combustion chamber metal structure (6) downstream of the electrode assembly. The concave cavity device (5) adopts a front step device or a rear step device to increase the mixing of fuel and airflow and stabilize combustion. The concave cavity device (5) forms a certain geometric volume downstream of the electrode assembly. When the high-speed airflow flows through the concave cavity opening, a stable low-speed recirculation zone will be formed inside the concave cavity. This recirculation zone can capture some fuel and already burned particles, allowing them to circulate and mix in the concave cavity for a longer time. Fuel is injected into the inner cavity of the combustion chamber metal structure (6) through the fuel injection hole (1) and mixed with the airflow. At the same time, the electrode assembly is controlled by an electrical switch to generate and annihilate the multi-channel sliding arc plasma discharge region through high frequency, thereby realizing high-frequency pulse disturbance of the flow field and enhancing the mixing of fuel and airflow. When the electrode is energized, the high temperature effect of the sliding arc causes the gas in the affected area to expand, generating a physical slope-like effect. An oblique shock wave is generated in the front of the plasma. When the fuel trajectory passes through the plasma-induced oblique shock wave with the airflow, it will deflect away from the wall, thereby increasing the height of fuel diffusion and improving fuel distribution. When the electrode is de-energized, the plasma annihilates, the shock wave disappears, and the flow field recovers. Through the physical effect of periodic generation and disappearance, a high-frequency pulse disturbance is applied to the downstream flow field of the fuel. By utilizing the mechanism that pulse disturbance can excite large-scale vortex structure and enhance fluid entrainment and diffusion, the mixing efficiency of fuel and airflow is significantly improved.

2. A hybrid enhancement method for pulse perturbation using plasma excitation, characterized in that, The hybrid enhancement device for pulse perturbation using plasma excitation as described in claim 1 includes the following steps: Using electrical control, the periodic switching of the electrode assembly between power on and power off is realized to generate sliding arc plasma. When the electrode is powered on, sliding arc plasma (60) is generated between the electrode anode (4) and the electrode cathode (3). The high temperature effect of the sliding arc causes the gas in the affected area to expand, generating a physical slope-like effect, and generating a sloping shock wave in the front of the plasma. When the electrode is de-powered, the plasma annihilates, the shock wave disappears, and the flow field recovers. Through the periodic generation and disappearance of the physical effect, a high-frequency pulse disturbance is applied to the downstream flow field of the fuel. By utilizing the effect of sliding arc plasma on the flow field, plasma-induced oblique shock waves are generated periodically, which pulses and disturbs the downstream flow field of fuel injection, promoting fuel mixing. When the fuel trajectory passes through the plasma-induced oblique shock wave with the airflow, it deflects away from the wall, thereby increasing the height of fuel diffusion and improving fuel distribution. The method has two injection states: conventional injection and plasma-excited injection. In the conventional injection state, the electrode assembly is not energized and no sliding arc plasma is generated. After fuel injection, it enters the downstream cavity shear layer and mixes with the mainstream and recirculation zone as the shear layer rolls up. In the plasma-excited injection state, the electrode assembly is energized, and sliding arc plasma is generated between the electrode anode (4) and electrode cathode (3). The high temperature effect of the sliding arc causes the gas in the affected area to expand, generating a physical ramp-like effect. Oblique shock waves are generated in the front of the plasma. When the fuel trajectory passes through the plasma-induced oblique shock wave with the airflow, it deflects away from the wall, thereby increasing the height of fuel diffusion and thus improving fuel distribution.

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