A toroidal sliding arc discharge excited plasma ignition and combustion assisting head

Abstract

A plasma ignition and combustion-supporting head excited by an annular sliding arc discharge is disclosed, with a flow-guiding support located on the outer ring of a swirl mount. An insulating component is located on the conical end face of the outlet end of the swirl mount. The combustion chamber ignition and combustion-supporting head generates a sliding arc between the high-voltage electrode ring and the outlet end of the swirl mount, fully coupling with the ejected fuel spray to achieve ignition and combustion support. The converging section of the insulating component is located at the inlet end of the aero-engine combustion chamber, and the expanding section is located at the outlet end. This invention generates a sliding arc between the high-voltage electrode ring and the swirl mount, effectively avoiding electrode ablation and preventing performance degradation of the fuel nozzle due to electrification. The positional relationship between the insulating component and the swirl mount ensures the discharge position and distance, thereby controlling the arc intensity. It can be directly installed in the combustion chamber for use, increasing the average temperature at the combustion chamber outlet and making the temperature distribution more uniform, thus improving combustion efficiency and ensuring more complete fuel combustion.

Description

Technical Field

[0001] This invention relates to plasma ignition and combustion technology in the field of aero-engines, specifically a three-dimensional rotating sliding arc plasma combustion chamber head for aero-engines. Background Technology

[0002] To meet the requirements of next-generation aero-engines, it is urgent to overcome numerous technical bottlenecks that restrict the efficient, stable, reliable, and safe operation of aero-engine combustors. Plasma ignition-assisted combustion technology is a novel technology that can be used to solve the ignition difficulties and combustion instability problems faced by aero-engines in high-altitude, low-pressure environments, and has become a research hotspot for scholars both domestically and internationally. From 2009 to 2014, the United States conducted a multidisciplinary research program on plasma-assisted combustion, aiming to promote the application of plasma technology in engineering. The Air Force Engineering University in China has also conducted extensive research on plasma igniters for aero-engine combustors, laying a solid foundation for the application of plasma technology in aero-engine combustors.

[0003] Current research indicates that applying plasma to the combustion chamber of an aero-engine can promote combustion rate and fuel combustion intensity, improve flame stability and ignition reliability, shorten ignition delay time, and also improve the temperature field distribution at the combustion chamber exit, reducing pollutant emissions. Domestic institutions such as Xi'an Jiaotong University and Beijing University of Aeronautics and Astronautics have also conducted research on sliding arc plasma in aero-engines, finding that sliding arc plasma has significant advantages compared to other plasma generation methods. Three-dimensional rotating sliding arc discharge can generate a larger discharge area, significantly increasing the contact area between fuel and the arc. Furthermore, sliding arc plasma has a high energy utilization rate, using up to 80% of the discharge power to promote fuel chemical reactions, generating a large number of active particles such as oxygen atoms, OH, and CH radicals. Moreover, sliding arc plasma can generate a rotating sliding arc through the rotating airflow within the combustion chamber, and the sliding arc plasma discharge structure can adapt well to the existing combustion chamber structure.

[0004] In 2014, the Air Force Engineering University of the Chinese People's Liberation Army proposed an elongated arc plasma igniter (such as...) in its invention patent application with publication number CN104454290A. Figure 1 As shown in the figure, the discharge between the cathode and the anode constriction section can increase the flame propagation speed and generate more active particles. However, the device generates a high-temperature arc near the cathode tip. Since the cathode tip is relatively sharp, the high-temperature arc can easily ablate the cathode. In addition, the device requires an external air evacuation device, which increases the overall complexity.

[0005] In 2017, the Air Force Engineering University disclosed a plasma combustion actuator (such as...) in its invention patent application with publication number CN107420199A. Figure 2As shown, this exciter generates sliding arc plasma by discharging between the cathode cone electrode and the anode shell. It has a simple structure, which is beneficial for increasing the flame propagation speed and increasing the contact area between the arc and the fuel. However, it also requires an external gas supply device. In addition, the discharge scheme adopted can easily make the entire outer edge of the igniter electrified, which poses certain safety hazards.

[0006] In 2018, the Air Force Engineering University published an invention patent with the publication number CN109057972A, which disclosed a pre-combustion type plasma igniter for aircraft engines (such as...). Figure 3 As shown, this device has a ceramic tube fuel channel installed inside the cathode section, which makes the reaction occur outside the anode, thus protecting the electrode and increasing safety. At the same time, it has multiple air inlets and generates rotating airflow through spiral grooves. Multiple air inlets are evenly opened around the lower outer wall of the outer tube to allow air to enter, and the spiral grooves make the airflow rotate, which acts as a cyclone separator. The structure is simple and easy to process. However, although the device has an insulating layer, some electrodes are still exposed to the air. In addition, the use of jet ignition also reduces the combustion effect to some extent.

[0007] In 2021, Shenyang Aerospace University disclosed a plasma igniter capable of generating a sliding arc in its invention patent application CN113915005A (such as...). Figure 4 As shown, the device uses a multi-electrode discharge method, which generates a sliding arc by rotating the ring electrode itself. It can produce a stable sliding arc, but the discharge structure is complex. At the same time, the multi-electrode structure increases the output power of the power supply and also generates some unnecessary energy loss, reducing the combustion-supporting effect.

[0008] In 2021, the Shenyang Engine Research Institute of Aero Engine Corporation of China disclosed a plasma ignition system (such as...) for axial-flow engines in its invention patent application CN114427497A. Figure 5 As shown, this system can generate a high-temperature, flame-stable plasma torch. However, since the whole system is a circular tube structure, it needs to be installed at the top of the combustion chamber flame tube. Therefore, active particles need to be generated in advance and then injected into the predetermined area of ​​the combustion chamber. The residence time of the active particles is relatively long, which increases the probability of recombination of the active particles and thus reduces the combustion-supporting effect.

[0009] Since conventional ignition, exciter and ignition systems often require external air injection devices and have problems with insufficient coupling between atomized fuel and electric arc, many scholars have carried out research on combustion chamber heads. This invention also designs a combustion chamber head that does not require an air injection device.

[0010] In 2018, the Air Force Engineering University of the Chinese People's Liberation Army disclosed a rotating sliding arc plasma fuel pyrolysis head for an aero-engine combustion chamber in invention patent CN108180075A (such as...). Figure 6 As shown, this device discharges between the anode venturi tube and the cathode horn, using a self-bleeding air method to drive the sliding arc. It has a simple structure and can be adapted to the existing structure of the aero-engine combustion chamber. However, the angle between the discharge area of ​​this device and the horizontal plane is too large, which is not conducive to the coupling of the electric arc and fuel, thus reducing the combustion-supporting effect to some extent.

[0011] In 2021, the Air Force Engineering University of the Chinese People's Liberation Army disclosed a combined dielectric barrier discharge plasma aero-engine combustion chamber head (such as...) in its invention patent application CN113776089A. Figure 7 As shown in the figure, this scheme discharges between the high-voltage electrode and the ground electrode, resulting in a large contact area between the fuel and the electric arc, which enables more complete combustion. It is also applicable to other combustion chambers with similar structures. However, the intake effect is not good, which affects the gas flow in the combustion chamber and results in a smaller discharge area, so there are still defects.

[0012] In 2021, the Air Force Engineering University of the Chinese People's Liberation Army disclosed a sliding arc plasma duty flame head for an aero-engine combustion chamber (such as...) in its invention patent application CN113898974A. Figure 8 As shown, this scheme generates two swirling streams (one forward and one reverse) through a two-stage cyclone separator, eliminating the need for an external air supply device. The swirling streams promote the mixing of fuel and air, and the discharge occurs between the cathode sleeve and the anode venturi tube, creating a discharge area conducive to fuel-arc coupling. However, although this scheme includes a fuel nozzle protection distance, the contact between the cathode sleeve and the nozzle still makes it difficult to solve the nozzle erosion problem. Furthermore, the cable installation method may lead to cable detachment, posing certain safety hazards.

[0013] In 2022, Harbin Institute of Technology disclosed a low-emission combustion chamber head structure for a gas turbine using a mixing cyclone in its invention patent application CN115342383A (e.g., Figure 9 As shown, a stable ignition source is provided through the pre-combustion stage, and a multi-stage cyclone separator is used to suppress combustion instability and reduce pollutant emissions. At the same time, the stability of the airflow at the main combustion stage outlet is ensured. However, the structure is relatively complex. In addition, the main combustion stage outlet does not adopt a convergent expansion structure, which is not conducive to the elongation of the electric arc. The coupling degree between the electric arc and the fuel is low, and the fuel cracking effect is poor.

[0014] In 2022, Beijing University of Aeronautics and Astronautics disclosed a low-emission combustor head design with interstage enhanced cooling in its invention patent application CN115307178A (e.g., Figure 10As shown, this scheme can improve the cooling conditions in the combustion chamber. The combustion chamber head contains multiple air intake holes and has multiple cooling structures, which can significantly improve the cooling effect and effectively avoid the burning damage of the interstage section. However, the axial distance between the fuel nozzle and the cascade section is too small, which can easily cause the atomized fuel to hit the wall of the cascade section, resulting in the accumulation of fuel droplets, which is not conducive to fuel atomization and cracking, and also affects the airflow stability.

[0015] The plasma igniters and exciters proposed in the aforementioned inventions have made certain contributions to improving the ignition performance, combustion efficiency, combustion stability, and fuel atomization effect of aero-engine combustors. However, they all have certain drawbacks, such as: complex devices unsuitable for aero-engine combustors; low fuel-arc coupling leading to poor fuel pyrolysis; and poor arc stability, making them susceptible to incoming flow interference. In summary, none of the inventions can meet the requirements of expanding the ignition boundary and stabilizing the combustion range for next-generation aero-engine combustors. Summary of the Invention

[0016] To overcome the difficulties in applying sliding arc plasma combustion technology to aero-engine combustion chambers, improve the ignition reliability of aero-engine combustion chambers, and broaden the ignition boundary, this invention proposes a plasma ignition and combustion head excited by annular sliding arc discharge.

[0017] This invention includes a fuel nozzle, a swirl mount, a flow guide support, an insulating component, a cable, and a high-voltage electrode ring. The fuel nozzle is located inside the swirl mount. The flow guide support is fitted onto the outer ring of the swirl mount, with the inner wall of the inner cylinder of the flow guide support tightly fitted to the cylindrical surface of the outer ring of the swirl mount. The insulating component is fitted onto the conical end face of the air outlet of the swirl mount, with the outer surface of the expanding section of the insulating component in close contact with the conical surface of the outer cylinder of the flow guide support, and the inner surface of the converging section of the insulating component maintaining close contact with the conical end face of the air outlet of the swirl mount. A cable sleeve on the insulating component extends into a cable sleeve mounting hole in the flow guide support. The high-voltage electrode ring is embedded in an electrode groove on the expanding section of the insulating component. The cable is located inside the cable hole in the insulator; the combustion chamber ignition and combustion-supporting head generates a sliding arc between the high-voltage electrode ring and the conical end face of the swirl mounting seat outlet, the axial distance of which is h7, and the discharge distance S2 = 15-17mm; this sliding arc is fully coupled with the fuel spray ejected from the fuel nozzle, thereby achieving the effect of ignition and combustion support. The conical end face of the swirl mounting seat outlet is in contact with the inner surface of the converging section of the insulator.

[0018] The inner surface of the outer ring is a conical surface with a taper of α2 = 7-9°, and the diameter of the inner surface circle of the air intake end of the outer ring is D2 = 73-76 mm; the outer surface of the outer ring is composed of a cylindrical surface and a conical surface; wherein, the diameter of the cylindrical segment is D3 = 88-92 mm and the axial length is h1 = 52-58 mm; the angle between the conical segment and the horizontal plane is α3, α3 = 42-47°, and the axial projection length of the conical segment on the horizontal plane is h2, h2 = 24-26 mm.

[0019] The airflow guide support includes an inner cylinder and an outer cylinder nested together, with the surface of the guide strips evenly distributed on the outer circumferential surface of the inner cylinder fitting against the inner surface of the outer cylinder. The gaps between adjacent guide strips on the outer circumferential surface of the inner cylinder form a direct-flow air intake channel.

[0020] The tensile strength σ of the flow guide support b ≥390 MPa, yield strength σ s ≥320Mpa, melting point ≥1800℃.

[0021] Nine to 15 guide strips 11 are evenly distributed axially on the outer circumferential surface of the inner cylinder; the radial height of the guide strips d3 = 4.5 to 4.8 mm, and the width L1 = 11 to 16 mm. The maximum axial length of the outer cylinder of the guide support is h3 = 75 to 80 mm, the outer diameter of the outer cylinder D4 = 126 to 134 mm, and the wall thickness of the outer cylinder d4 = 7 to 9 mm.

[0022] A cable sleeve mounting hole with a diameter D5 = 6-8mm is machined on the inner cylinder of the flow guide support. The distance S1 from the center axis of the cable sleeve mounting hole to the center of the flow guide support is 50-52mm.

[0023] The swirl mounting base includes an inner ring, multiple swirl blades, and an outer ring. The swirl blades are fixed between the inner and outer rings of the swirl mounting base, and there is an installation angle between the air inlet and outlet ends of the swirl blades. This installation angle forms the swirl angle α1 of the swirl mounting base, where α1 = 20–35° and the thickness of the swirl blades δ1 = 1.4–1.6 mm. Swirl intake channels are formed between each swirl blade, and incoming air enters the fuel-air premixing zone through each swirl intake channel. The inner diameter of the inner ring of the swirl mounting base is D1 = 8–10 mm, and the inner ring wall thickness is d1 = 4.2–4.4 mm.

[0024] The insulating component is divided into a converging section and an expanding section, forming a rotating body that first converges and then expands. The converging section of the insulating component is located at the air inlet end of the aero-engine combustion chamber, and the expanding section is located at the air outlet end of the aero-engine combustion chamber. Wherein:

[0025] The angle between the converging section of the insulating component and the horizontal plane is the same as the angle between the cylindrical surface and the conical surface on the outer ring of the vortex mounting base, which is 42-47°; the wall thickness of the converging section is δ2 = 6.8-8.0 mm, and its projected length on the horizontal plane is the same as the projected length of the conical ring section of the vortex mounting base on the horizontal plane, which is 24-26 mm; the angle between the expanding section of the insulating component and the horizontal plane is α4 = 72-80°, and this angle is the same as the angle between the conical surface of the outer cylinder of the flow guide support and the horizontal plane; the thickness of the expanding section is δ3 = 10-12 mm, and the projected length of the expanding section on the horizontal plane is h4 = 20-22 mm.

[0026] The expansion section of the insulating component has two rings of evenly distributed swirling holes of the same diameter along its circumference. Each swirling hole is an oblique hole inclined towards the center of the insulating component, ensuring that the air inlet and outlet of each swirling hole are not on the same circumference, and that the central axis of each swirling hole has the same angle with the horizontal plane. The inner ring has 12-14 swirling holes, and the outer ring has 20-24 swirling holes; the diameter of the swirling holes, D6, is 3.5-5.2 mm. The distance between the center of the air inlet end of each inner ring swirling hole and the center of the insulating component is 40-42 mm, and the distance between the center of the air outlet end and the center of the insulating component is 33-35 mm; the distance between the center of the air inlet end of each outer ring swirling hole and the center of the insulating component is 45-47 mm, and the distance between the center of the air outlet end and the center of the insulating component is 38-40 mm.

[0027] The electrode groove is located on the inner surface of the expansion section of the insulating component. The top surface of the electrode groove is parallel to the surface of the expansion section, and there is a clearance fit between the high-voltage electrode ring and the electrode groove. The axial distance h5 from the middle of the bottom of the electrode groove to the air inlet end of the insulating component is 35-38 mm.

[0028] The cable sleeve is located on the expansion section of the insulation component and extends along the axial direction of the insulation component toward the air inlet end of the flow guide support.

[0029] The outer surface of the high-voltage electrode ring is a conical surface, and its external dimensions are adapted to the dimensions of the electrode groove. The high-voltage electrode ring has a thickness δ4 = 3.2~3.5mm, a length L2 = 22~24mm, an inner diameter D8 = 45~47mm, and an outer diameter D9 = 54~57mm.

[0030] The resistivity of the high-voltage electrode ring is ρ = 1.59 * 10⁻⁶. -8 ~1.62*10 -8 Ω·m, elongation δ = 6.5%–7%.

[0031] The insulating component used in this invention contains a cable sleeve with a relatively large wall thickness, which can effectively prevent leakage of the cable due to excessive voltage. At the same time, the high-voltage electrode ring is kept at a certain distance from the non-discharge metal parts, making it easy to control the discharge area.

[0032] This invention employs a discharge scheme that generates a sliding arc between the high-voltage electrode ring and the swirl mounting base. Unlike traditional discharge methods that occur between the fuel injector and the electrode, this effectively avoids electrode erosion and prevents performance degradation of the fuel injector due to electrification. The high-voltage electrode ring is embedded in an electrode groove on an insulating component. The positional relationship between the insulating component and the swirl mounting base ensures the discharge position and distance, thereby controlling the arc intensity.

[0033] This invention provides two air intake methods: a swirling intake channel and a direct intake channel, eliminating the need for a supplementary air device. The first method involves incoming air entering the fuel-air premixing zone through the swirling blades of the swirling mounting base. This intake channel is the swirling intake channel 27. The airflow gradually approaches the center of the rotating body through the inner surface of the outer ring of the swirling mounting base, which has a certain taper, and forms a counter-clockwise rotating swirling gas under the action of the swirling blades. The second method involves incoming air entering through the gaps in the guide strips on the guide support base. This intake channel is the direct intake channel 28. The airflow then flows into the premixing zone through the swirling holes on the insulating component. This portion of the airflow entering through the gaps in the guide strips flows out through the swirling holes on the expansion section of the insulating ceramic component, forming swirling gas. This swirling gas can also cause the electric arc to lengthen, making it a three-dimensional rotating sliding arc, extending towards the center of rotation, thus increasing the contact area between the electric arc and the fuel. After the two airflows enter the premixing zone, they are fully mixed with the fuel to form a uniform fuel-air mixture. The mixture is fully coupled with the three-dimensional rotating sliding arc, thereby improving the temperature field at the combustion chamber outlet and enhancing combustion efficiency.

[0034] This invention is combined with the head of the aircraft engine combustion chamber. Its structural dimensions are completely matched with the combustion chamber, without changing the original size and structure of the combustion chamber, and can be directly installed in the combustion chamber for use.

[0035] This invention enables more complete combustion, improves the overall performance of the combustion chamber, and features a simple structure, convenient manufacturing and installation, and strong versatility. Furthermore, this structure can be applied to other combustion chambers with similar structures, providing a certain approach for ignition and combustion assistance in next-generation aero-engine combustion chambers. This invention relates to plasma ignition and combustion assistance technology in the field of aero-engines, specifically developing a novel three-dimensional rotating sliding arc plasma combustion chamber head for aero-engines. This head can be used to improve the ignition performance of next-generation engine combustion chambers and can improve the combustion chamber outlet temperature field distribution, thereby enhancing combustion stability. Under a fuel-to-air ratio of 1, the combustion chamber outlet temperature field distribution under 200V plasma excitation and conventional combustion conditions are shown below. Figure 19 and Figure 20 As shown. Comparison Figure 19 and Figure 20It can be seen that after applying plasma excitation, the average temperature at the combustion chamber outlet increases and the temperature distribution becomes more uniform. This is because applying plasma-assisted combustion can promote fuel pyrolysis, improve fuel atomization, and thus improve combustion stability.

[0036] An AC high-voltage plasma power supply is applied to a cable connected to the high-voltage electrode ring, forming a breakdown arc between the swirl mount and the high-voltage electrode ring. This invention uses air as the working medium; the incoming air drives the arc to move within the space at the nozzle exit, forming a large-volume plasma excitation region where fuel pyrolysis and combustion occur, accelerating the chemical reaction process and improving combustion performance in the combustion chamber. The combustion efficiency 25 of conventional combustion and the fuel combustion efficiency 26 at a plasma power input of 800W are compared under different residual gas coefficients. Figure 21 As shown. Comparing the two, it is found that applying sliding arc plasma excitation can improve combustion efficiency to varying degrees under different residual gas coefficients. When the residual gas coefficient is equal to 1.6, the combustion efficiency of conventional combustion and the fuel combustion efficiency when the plasma power input power is 800W are 47% and 59%, respectively. At this time, applying plasma excitation improves the combustion efficiency by 25.5% compared with conventional combustion, making the fuel combustion more complete. Attached Figure Description

[0037] Figure 1 It is a long arc plasma igniter developed by the Air Force Engineering University of the Chinese People's Liberation Army.

[0038] Figure 2 It is a rotating sliding arc plasma combustion exciter for aero-engine combustion chambers invented by the Air Force Engineering University.

[0039] Figure 3 It is a pre-combustion plasma igniter for aircraft engines invented by the Air Force Engineering University.

[0040] Figure 4 It is a sliding arc plasma igniter developed by Shenyang Aerospace University.

[0041] Figure 5 It is a plasma ignition system invented by the Shenyang Engine Research Institute that can be used in axial-flow engines.

[0042] Figure 6 This is a rotating sliding arc plasma fuel pyrolysis head for an aero-engine combustion chamber, invented by the Air Force Engineering University.

[0043] Figure 7 This is a combined dielectric barrier discharge plasma aero-engine combustion chamber head invented by the Air Force Engineering University.

[0044] Figure 8This is a sliding arc plasma duty flame head for an aero-engine combustion chamber invented by the Air Force Engineering University.

[0045] Figure 9 This invention, developed by Harbin Institute of Technology, describes a low-pollution combustion chamber head structure for a gas turbine that utilizes a mixing cyclone.

[0046] Figure 10 This is a low-emission combustion chamber head design with enhanced interstage cooling invented by Beijing University of Aeronautics and Astronautics.

[0047] Figure 11 This is a schematic diagram of the structure of the present invention.

[0048] Figure 12 This is a schematic diagram of a fuel nozzle structure.

[0049] Figure 13 This is a schematic diagram of the swirl mounting base; where, Figure 13 'a' is the main view. Figure 13 b is Figure 13 Left view of a Figure 13 c is Figure 13 b is a sectional view from section AA.

[0050] Figure 14 This is a schematic diagram of the flow guide support; in which, Figure 14 'a' is the main view. Figure 14 b is Figure 14 The left view of a.

[0051] Figure 15 This is a schematic diagram of the insulating component; among which, Figure 15 'a' is the main view. Figure 15 b is Figure 15 The left view of a; Figure 15 c is Figure 15 The rear view of a.

[0052] Figure 16 This is a schematic diagram of the cable structure; in which, Figure 16 'a' is the main view. Figure 16 b is Figure 16 The left view of a.

[0053] Figure 17 This is a schematic diagram of the high-voltage electrode ring structure; among which, Figure 17 'a' is the main view. Figure 17 b is Figure 17 The left view of a.

[0054] Figure 18 This is a schematic diagram of the discharge distance between the swirl mounting base and the high-voltage electrode ring.

[0055] Figure 19This is a diagram showing the temperature field distribution at the combustion chamber outlet when the oil-to-gas ratio is 1 and 200V plasma excitation is applied.

[0056] Figure 20 This is the temperature field distribution at the combustion chamber outlet under conventional combustion when the air-fuel ratio is 1.

[0057] Figure 21 These are the combustion efficiencies of conventional combustion and the fuel combustion efficiency when the plasma power input is 800W, under different residual gas coefficients.

[0058] In the diagram: 1. Fuel nozzle; 2. Swirl mount; 3. Flow guide support; 4. Insulator; 5. Cable; 6. High-voltage electrode ring; 7. Inner ring; 8. Swirl blade; 9. Outer ring; 10. Inner cylinder; 11. Flow guide strip; 12. Outer cylinder; 13. Cable sleeve mounting hole; 14. Swirl hole; 15. Cable sleeve; 16. Cable hole; 17. Electrode groove; 18. Sliding arc; 19. Fuel spray; 20. Cylindrical surface of the outer ring of the swirl mount; 21. Conical end face of the outlet of the swirl mount; 22. Conical surface of the outer cylinder of the flow guide support; 23. Inlet end of the insulator; 24. Inner surface of the expansion section of the insulator; 25. Combustion efficiency of conventional combustion; 26. Fuel combustion efficiency when the plasma power input is 800W; 27. Swirl intake channel; 28. Direct current intake channel. Detailed Implementation

[0059] This embodiment is a plasma ignition and combustion aid head excited by an annular sliding arc discharge, including a fuel nozzle 1, a swirl mounting base 2, a flow guide support 3, an insulating component 4, a cable 5, and a high-voltage electrode ring 6. The fuel nozzle 1 is located inside the swirl mounting base 2, and its inlet end is connected to the fuel tank. The flow guide support 3 is fitted onto the outer annular cylindrical surface 20 of the swirl mounting base, and the inner wall surface of the inner cylinder of the flow guide support 3 is in close contact with the outer annular cylindrical surface of the swirl mounting base. The insulating component 4 is slowly fitted onto the conical end face 21 of the vortex mounting base from the outlet end to the inlet end, until the inlet end 23 of the insulating component is parallel to the outlet end face of the inner cylinder of the guide support base. The outer surface of the expanding section of the insulating component is in close contact with the conical surface 22 of the outer cylinder of the guide support base, and the inner surface of the converging section of the insulating component is in close contact with the conical end face 21 of the outlet end of the vortex mounting base. At this time, the cable sleeve 15 on the insulating component extends into the cable sleeve mounting hole 13 of the guide support base and maintains a clearance fit with the cable sleeve mounting hole, that is, the outer surface of the cable sleeve and the surface of the cable sleeve mounting hole are mating surfaces. The high-voltage electrode ring 6 is embedded in the electrode groove 17 machined in the expanding section of the insulating component, and the gap between the electrode groove and the high-voltage electrode ring is filled with high-temperature resistant sealant. The cable 5 is located within the cable hole 16 in the insulating component 4, with one end connected to an external power supply and the other end contacting and energizing the high-voltage electrode ring 6 embedded in the electrode groove 17. The combustion chamber ignition and combustion-supporting head generates a sliding arc 18 between the high-voltage electrode ring and the conical end face of the swirl mounting seat outlet. The position and discharge distance of the sliding arc are determined by the positional relationship between the swirl mounting seat and the insulating component. The axial distance of the generated sliding arc is h7, and the discharge distance S2 = 15-17 mm. The conical end face 21 of the swirl mounting seat outlet is in contact with the inner surface of the converging section of the insulating component. The generated sliding arc 18 fully couples with the fuel spray 19 ejected from the fuel nozzle 1, thereby achieving the effect of ignition and combustion support.

[0060] The swirl mounting base 2 is made of a high-temperature resistant ductile metal alloy, manufactured by 3D printing, machining, or casting, and has a rotating structure. In this embodiment, it is made of iron-carbon alloy material using 3D printing. The swirl mounting base includes an inner ring 7, multiple swirl blades 8, and an outer ring 9. The swirl blades are trapezoidal, made of stainless steel 301, and formed by hot pressing and welded between the inner and outer rings of the swirl mounting base. An installation angle is formed between the air inlet and outlet ends of the swirl blades, creating a swirl angle α1 of the swirl mounting base, where α1 = 20–35°, and the blade thickness δ1 = 1.4–1.6 mm. Swirl intake channels 27 are formed between the blades, allowing incoming air to enter the fuel-air premixing zone. The inner diameter of the inner ring of the swirl mounting base is D1 = 8–10 mm, and the inner ring wall thickness is d1 = 4.2–4.4 mm.

[0061] The inner surface of the outer ring 8 is a conical surface with a taper of α2 = 7-9°, and the diameter of the inner surface circle of the air intake end of the outer ring is D2 = 73-76 mm; the outer surface of the outer ring is composed of a cylindrical surface and a conical surface; wherein, the diameter of the cylindrical segment is D3 = 88-92 mm and the axial length is h1 = 52-58 mm; the angle between the conical segment and the horizontal plane is α3, α3 = 42-47°, and the axial projection length of the conical segment on the horizontal plane is h2, h2 = 24-26 mm.

[0062] The flow guide support 3 is made of high-temperature resistant alloy material, integrally formed by machining or 3D printing technology, and finally subjected to surface hardening treatment. Its tensile strength σ b ≥390 MPa, yield strength σ s ≥320 MPa, melting point ≥1800℃. The flow guide support includes an inner cylinder 10 and an outer cylinder 12, wherein the outer cylinder 12 is fitted onto the inner cylinder 10, and the surfaces of the evenly distributed flow guide strips 11 on the outer circumferential surface of the inner cylinder are in contact with the inner surface of the outer cylinder. The gaps between adjacent flow guide strips on the outer circumferential surface of the inner cylinder form a direct current intake channel 28.

[0063] The inner cylinder 10 has the same inner diameter as the outer diameter of the vortex mounting base 2, and the inner cylinder wall thickness d2 = 15-20 mm. Nine to 15 strip-shaped bosses are evenly distributed axially on the outer circumferential surface of the inner cylinder; each boss is a guide strip 11; the radial height of the guide strip d3 = 4.5-4.8 mm, and the width L1 = 11-16 mm. The outer diameter of the inner cylinder at each guide strip is the same as the inner diameter of the outer cylinder. The maximum axial length h3 of the outer cylinder of the guide support base is 75-80 mm, the outer diameter D4 is 126-134 mm, and the outer cylinder wall thickness d4 = 7-9 mm. Furthermore, the axial lengths of the guide strips, the inner cylinder of the guide support base, and the inner ring of the vortex mounting base are all equal, with a length of 56-64 mm.

[0064] A cable sleeve mounting hole 13 with a diameter D5 = 6-8 mm is machined on the inner cylinder of the flow guide support. The distance S1 from the center axis of the cable sleeve mounting hole to the center of the flow guide support is 50-52 mm. The conical surface 22 of the outer cylinder of the flow guide support is in close contact with the outer surface of the expansion section of the insulating component.

[0065] The insulating component 4 is a hollow rotating body, manufactured in an integrated manner using high-temperature resistant and highly insulating ceramic material through integral ceramic processing, machining, or 3D printing technology. The insulating component includes a swirling orifice, a cable sleeve, an electrode groove, and a cable hole. The longitudinal section of the insulating component is generally V-shaped, consisting of a converging section and an expanding section, forming a rotating body that first converges and then expands. The converging section of the insulating component is located at the air inlet end of the aero-engine combustion chamber, and the expanding section is located at the air outlet end of the aero-engine combustion chamber.

[0066] The angle between the converging section of the insulating component and the horizontal plane is the same as the angle between the cylindrical surface and the conical surface on the outer ring of the vortex mounting base, which is 42-47°. The wall thickness of the converging section is δ2 = 6.8-8.0 mm, and the projected length of the converging section of the insulating component on the horizontal plane is the same as the projected length of the conical ring section of the vortex mounting base on the horizontal plane, which is 24-26 mm. The angle between the expanding section of the insulating component and the horizontal plane is α4 = 72-80°, and this angle is the same as the angle between the conical surface of the outer cylinder of the flow guide support and the horizontal plane. The thickness of the expanding section is δ3 = 10-12 mm, and the projected length of the expanding section on the horizontal plane is h4 = 20-22 mm.

[0067] Two concentric rings of swirling holes 14 of the same diameter are machined on the expansion section of the insulating component. Each swirling hole is an oblique hole inclined towards the center of the insulating component, so that the air inlet and outlet of each swirling hole are not on the same circumference, and the central axis of each swirling hole has the same angle with the horizontal plane. The inner ring has 12-14 swirling holes, and the outer ring has 20-24 swirling holes; the diameter D6 of the swirling holes is 3.5-5.2 mm. The distance between the center of the air inlet end of each inner ring swirling hole and the center of the insulating component is 40-42 mm, and the distance between the center of the air outlet end and the center of the insulating component is 33-35 mm; the distance between the center of the air inlet end of each outer ring swirling hole and the center of the insulating component is 45-47 mm, and the distance between the center of the air outlet end and the center of the insulating component is 38-40 mm. In this embodiment, the number of swirling holes in the inner ring is 12, and the number of swirling holes in the outer ring is 20.

[0068] The inner surface 24 of the expansion section of the insulating component is machined with an electrode groove 17 for installing a high-voltage electrode ring. The bottom surface of the electrode groove is parallel to the surface of the expansion section, and the upper wall surface of the groove is parallel to the surface of the expansion section. The surfaces of the high-voltage electrode ring and the electrode groove are conical surfaces, and the high-voltage electrode ring and the electrode groove are in clearance fit. The depth and length of the electrode groove change with the size of the high-voltage motor ring. In the same vertical plane, the horizontal distance h5 between the bottom of the electrode groove and the air inlet end of the insulating component is 35-38 mm. The cable sleeve 15 is located on the expansion section of the insulating component and extends along the axial direction of the insulating component towards the air inlet end of the flow guide support 3. A cable hole 16 with the same diameter as its inner diameter is machined along the central axis of the cable sleeve and penetrates the entire insulating component for cable installation. When the insulating component is assembled with the flow guide support, the cable sleeve is inserted into the cable sleeve mounting hole 13 on the flow guide support, and the two are in clearance fit.

[0069] During assembly, the inner surface of the converging section of the insulating component is in close contact with the conical end face of the air outlet of the vortex mounting base, and the outer surface of the expanding section of the insulating component is in close contact with the conical surface of the outer cylinder of the flow guide support base. At the same time, the cable sleeve on the insulating component and the cable sleeve mounting hole on the flow guide support base maintain a clearance fit, and the air inlet end face of the cable sleeve and the air inlet end face of the flow guide support base are on the same vertical plane.

[0070] The high-voltage electrode ring 6 is circular and made of a metal foil with good conductivity and ductility, with a resistivity ρ = 1.59 × 10⁻⁶. -8 ~1.62*10 -8 The high voltage electrode ring has an Ω·m elongation of δ = 6.5%–7%. The outer surface of the high voltage electrode ring is conical, and its dimensions are adapted to the dimensions of the electrode groove 17. The high voltage electrode ring has a thickness δ4 = 3.2–3.5 mm, a length L2 = 22–24 mm, an inner diameter D8 = 45–47 mm, and an outer diameter D9 = 54–57 mm.

[0071] The high-voltage electrode ring is embedded in the electrode groove on the insulating component, with its conical surface adhering to the groove wall surface. ZS-1071 high-temperature resistant inorganic adhesive is used to fill the minute gap between the high-voltage electrode ring and the groove surface, thereby fixing the high-voltage electrode ring in place on the insulating component and preventing it from detaching. The outer surface of the high-voltage electrode ring embedded in the electrode groove 17 is adhering to the bottom surface of the groove. The inner surface of the high-voltage electrode ring, after being embedded in the groove, remains flush with the inner surface 24 of the expanded section of the insulating component.

[0072] The high-voltage electrode ring is embedded in the electrode groove on the insulating component from the outlet end to the inlet end, with the larger end of the high-voltage electrode ring facing the outlet end. A high-temperature resistant adhesive is filled in the gap between the high-voltage electrode ring and the electrode groove to fix the position of the high-voltage electrode ring on the insulating component and prevent it from falling off. Furthermore, the inner surface of the high-voltage electrode ring after embedding in the electrode groove remains flush with the outer surface of the expanded section of the insulating component.

[0073] The fuel nozzle 1, swirl mounting base 2, flow guide support 3, insulating component 4, cable 5, and high-voltage electrode ring 6 are coaxial; the air inlet end of the swirl mounting base and the air inlet end of the flow guide support are on the same vertical plane. The fuel nozzle 1 is made of a nickel-based alloy with good corrosion resistance and high-temperature resistance, and is a centrifugal nozzle. The atomization cone angle of the fuel nozzle is 98-123°, and the outer surface of the fuel nozzle is in close contact with the inner surface of the inner ring of the swirl mounting base.

[0074] The cable is manufactured using existing technology. The outer insulation layer material is polyvinyl chloride, polyethylene, etc., which have good insulation and wear resistance. The inner conductor material is non-ferrous metal materials such as copper and tin-clad copper wire, which have excellent conductivity. The cable is installed in the cable hole on the insulation component with a diameter D7 = 3.0~3.3mm and a length h6 = 80~90mm.

[0075] Under different residual gas coefficients, the combustion efficiency 25 of conventional combustion and the fuel combustion efficiency 26 when the plasma power input is 800W are as follows: Figure 21 As shown in the figure, the comparison between the two shows that applying sliding arc plasma excitation can improve combustion efficiency to varying degrees. When the residual gas coefficient is equal to 1.6, the combustion efficiency of conventional combustion and the fuel combustion efficiency when the plasma power input power is 800W are 47% and 59%, respectively. At this time, applying plasma excitation improves the combustion efficiency by 25.5% compared with conventional combustion, making the fuel combustion more complete.

[0076] This invention illustrates its technical solution through three specific embodiments. The structures of each embodiment are identical, differing only in their technical parameters, as detailed in Table 1.

[0077] Table 1

[0078]

[0079]

Claims

1. A plasma ignition and combustion aid head excited by an annular sliding arc discharge, characterized in that, The device includes a fuel nozzle (1), a swirl mount (2), a flow guide support (3), an insulating component (4), a cable (5), and a high-voltage electrode ring (6). The fuel nozzle is located inside the swirl mount. The flow guide support is fitted onto the outer ring of the swirl mount, and the inner wall of the inner cylinder of the flow guide support is in close contact with the cylindrical surface of the outer ring of the swirl mount. The insulating component is fitted onto the conical end face of the outlet end of the swirl mount, and the outer surface of the expanding section of the insulating component is in close contact with the conical surface (22) of the outer cylinder of the flow guide support, and the inner surface of the converging section of the insulating component is in close contact with the conical end face (21) of the outlet end of the swirl mount. A cable sleeve (15) is attached to the insulating component. The cable sleeve is inserted into the cable sleeve mounting hole (13) of the flow guide support seat; the high voltage electrode ring (6) is embedded in the electrode groove (17) on the expansion section of the insulating component; the cable (5) is located in the cable hole (16) in the insulating component (4); the combustion chamber ignition and combustion assisting head generates a sliding arc (18) between the high voltage electrode ring and the conical end face of the gas outlet of the swirl mounting seat, the axial distance of the sliding arc is h7, and the discharge distance S2 = 15~17mm; the sliding arc is fully coupled with the fuel spray (19) sprayed from the fuel nozzle (1), thereby achieving the effect of ignition and combustion assisting; the conical end face (21) of the gas outlet of the swirl mounting seat is in contact with the inner surface of the converging section of the insulating component.

2. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, The inner surface of the outer ring (9) is a conical surface with a taper of α2 = 7~9°, and the diameter of the inner surface circle of the air inlet end of the outer ring is D2 = 73~76mm; the outer surface of the outer ring is composed of a cylindrical surface and a conical surface; wherein, the diameter of the cylindrical section is D3 = 88~92mm and the axial length is h1 = 52~58mm; the angle between the conical section and the horizontal plane is α3, α3 = 42~47°, and the axial projection length of the conical section on the horizontal plane is h2, h2 = 24~26mm.

3. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, The flow guide support includes an inner cylinder (10) and an outer cylinder (12) nested together, with the surface of the flow guide strips (11) evenly distributed on the outer circumferential surface of the inner cylinder in contact with the inner surface of the outer cylinder; the gap between each adjacent flow guide strip on the outer circumferential surface of the inner cylinder forms a direct current intake channel (28); the tensile strength σ of the flow guide support (3) b ≥390 MPa, yield strength σ s ≥320Mpa, melting point ≥1800℃.

4. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, The swirl mounting base includes an inner ring (7), multiple swirl blades (8), and an outer ring (9); wherein the swirl blades are fixed between the inner and outer rings of the swirl mounting base, and there is an installation angle between the air inlet end and the air outlet end of the swirl blades, which forms the swirl angle α1 of the swirl mounting base, α1=20~35°, and the thickness of the swirl blades δ1=1.4~1.6mm; a swirl air inlet channel (27) is formed between each swirl blade, and the incoming air enters the fuel-air premixing zone from each of the swirl air inlet channels; the inner diameter of the inner ring of the swirl mounting base is D1=8~10mm, and the inner ring wall thickness is d1=4.2~4.4mm.

5. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, Nine to fifteen guide strips (11) are evenly distributed along the axial direction on the outer circumferential surface of the inner cylinder; the radial height of the guide strip is d3 = 4.5 to 4.8 mm, and the width is L1 = 11 to 16 mm; the maximum axial length of the outer cylinder of the guide support is h3 = 75 to 80 mm, the outer diameter of the outer cylinder is D4 = 126 to 134 mm, and the wall thickness of the outer cylinder is d4 = 7 to 9 mm.

6. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, A cable sleeve mounting hole (13) with a diameter D5=6~8mm is machined on the inner cylinder of the flow guide support. The distance S1 from the center axis of the cable sleeve mounting hole to the center of the flow guide support is 50~52mm.

7. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, The insulating component (4) is divided into a converging section and an expanding section, forming a rotating body that first converges and then expands through the converging and expanding sections; the converging section of the insulating component is located at the air inlet end of the aero-engine combustion chamber, and the expanding section of the insulating component is located at the air outlet end of the aero-engine combustion chamber; wherein: The angle between the converging section of the insulating component and the horizontal plane is the same as the angle between the cylindrical surface and the conical surface on the outer ring of the vortex mounting base, which is 42~47°; the wall thickness of the converging section is δ2=6.8~8.0mm, and the projected length of the converging section of the insulating component on the horizontal plane is the same as the projected length of the conical ring section of the vortex mounting base on the horizontal plane, which is 24~26mm; the angle between the expanding section of the insulating component and the horizontal plane is α4=72~80°, and this angle is the same as the angle between the conical surface of the outer cylinder of the flow guide support and the horizontal plane; the thickness of the expanding section is δ3=10~12mm, and the projected length of the expanding section on the horizontal plane is h4=20~22mm; Two concentric rings of swirling holes (14) of the same diameter are evenly distributed along the circumference of the expansion section of the insulating component. Each swirling hole is an oblique hole inclined towards the center of the insulating component, so that the air inlet and outlet of each swirling hole are not on the same circumference, and the central axis of each swirling hole has the same angle with the horizontal plane. The number of swirling holes in the inner ring is 12 to 14, and the number of swirling holes in the outer ring is 20 to 24. The diameter of the swirling holes is D6 = 3.5 to 5.2 mm. The distance between the center of the air inlet end of each inner ring swirling hole and the center of the insulating component is 40 to 42 mm, and the distance between the center of the air outlet end and the center of the insulating component is 33 to 35 mm. The distance between the center of the air inlet end of each outer ring swirling hole and the center of the insulating component is 45 to 47 mm, and the distance between the center of the air outlet end and the center of the insulating component is 38 to 40 mm.

8. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 7, characterized in that, The electrode groove (17) is located on the inner surface of the expansion section of the insulating component; the top surface of the electrode groove is parallel to the surface of the expansion section, the high voltage electrode ring and the electrode groove are fitted with a clearance, and the axial distance h5 from the middle of the bottom of the electrode groove to the air inlet end of the insulating component is 35~38mm.

9. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, The cable sleeve is located on the expansion section of the insulation and extends along the axial direction of the insulation towards the air inlet end of the flow guide support (3).

10. The plasma ignition and combustion aid head excited by an annular sliding arc discharge as described in claim 1, characterized in that, The outer surface of the high-voltage electrode ring (6) is conical, and its dimensions are adapted to the dimensions of the electrode groove (17). The high-voltage electrode ring has a thickness δ4 = 3.2~3.5 mm, a length L2 = 22~24 mm, an inner diameter D8 = 45~47 mm, and an outer diameter D9 = 54~57 mm. The resistivity of the high-voltage electrode ring is ρ = 1.59 × 10⁻⁶. -8 ~1.62×10 -8 Ω·m, elongation δ=6.5%~7%.

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