An optical combustor for visualizing a sliding arc plasma assisted combustion full process

Abstract

The application belongs to the field of burners, and specifically discloses an optical burner for visualizing the whole process of sliding arc plasma assisted combustion, which comprises a visible furnace body, a low-shielding discharge assembly and an optical correction assembly, wherein: the bottom of the visible furnace body is provided with an air inlet, the inside of the visible furnace body is provided with a fuel pipe, and the visible furnace body is provided with an observation window; the low-shielding discharge assembly is arranged in the inside of the fuel pipe and comprises, from bottom to top, an electrode rod, a high-voltage electrode and a spiral electrode, one end of the electrode rod is connected with a high-voltage power supply, the other end of the electrode rod is connected with the high-voltage electrode, and a cyclone gas ring is arranged outside the electrode rod; one end of the spiral electrode is close to the high-voltage electrode, and the other end of the spiral electrode is connected with a grounding electrode terminal to realize grounding; the inner optical lens of the optical correction assembly is arranged outside the fuel pipe, and the outer optical lens of the optical correction assembly is arranged outside the visible furnace body. The application can realize full-process, full-angle and distortion-free observation of the occurrence-evolution-disappearance of an electric arc, and solves the problem of arc visualization in the inside of the burner.

Description

Technical Field

[0001] This application belongs to the field of burners, and more specifically, relates to an optical burner that visualizes the entire process of sliding arc plasma-assisted combustion. Background Technology

[0002] Zero-carbon, low-activity fuels such as ammonia or low-concentration combustible gases generally suffer from ignition difficulties and poor flame stability. Plasma, with its high chemical reactivity, can generate electrons, ions, and free radicals to improve the combustion of low-activity fuels like ammonia, making it a promising assisted combustion technology. Currently, plasmas used in burners for exciting combustion can be broadly categorized into three types based on their discharge patterns: dielectric barrier discharge, nanosecond pulse discharge, and sliding arc discharge. Among these, sliding arc plasma is gaining increasing attention in the field of plasma-assisted combustion due to its advantages such as high concentration of active substances, ease of generation, and simple equipment. Understanding the control mechanisms of sliding arc-assisted combustion is crucial for designing efficient and low-pollution burners. Currently, a thorough understanding of the control mechanisms of sliding arc-assisted combustion requires three-dimensional modeling and simulation; obtaining accurate sliding arc morphology is a critical aspect of this process. However, sliding arcs typically exist within the burner and between electrodes, making them difficult to observe due to structural obstruction.

[0003] Existing reports have focused on discussing plasma discharge performance and the optimized design of discharge components. For example, Chinese patent CN115597058A discloses a burner and method for suppressing combustion oscillations using rotating sliding arc discharge plasma. This patent uses a central blunt high-voltage electrode and a ground electrode on the burner shell to generate a three-dimensional rotating sliding arc to promote combustion. Combustion oscillations are suppressed by adjusting the discharge frequency to an integer multiple of the flame pulsation frequency. However, this patent aims to suppress combustion oscillations, and the burner and electrode structure design is relatively simple. It only considers structural strength and conductivity by using a fully enclosed metal burner and electrode, failing to achieve the ability to photograph and observe the arc generation and evolution process inside the burner. Chinese patent CN119468250A discloses a circumferentially distributed multi-path sliding arc igniter and its operating method. To improve combustion efficiency, this patent generates multi-path sliding arc plasma by setting multiple high-voltage electrodes along the circumference, increasing the contact area with the fuel and simultaneously improving the total discharge power of the sliding arc, significantly enhancing the ignition capability of the igniter. However, its structure dictates that the generated rotating sliding arc can only be photographed axially from the outside of the burner, not radially. Due to overlapping and obstruction of the field of view, the true morphology and evolution of the sliding arc cannot be reconstructed. Chinese patent CN119393791A discloses a high-power sliding arc igniter based on gas-liquid cooled electrodes and its operating method. To improve the lifespan of the sliding arc electrode, it proposes using a hollow electrode injected with liquid ammonia to cool the electrode, simultaneously achieving functions such as assisting ammonia combustion, reducing electrode temperature to increase electrode lifespan, and increasing discharge power. The rotating sliding arc generated by this plasma burner can be ejected from the burner outlet to further contact the fuel and enhance combustion. However, it can only capture images after the arc is ejected to the outside of the burner, with a high-speed camera positioned axially and radially at the burner outlet to construct the three-dimensional morphology of the sliding arc after it partially detaches from the burner. The breakdown formation and development process of the sliding arc inside the burner cannot be captured, making it impossible to observe and reconstruct the entire three-dimensional development process of the sliding arc.

[0004] In summary, due to structural and material limitations, burners using sliding arc plasma-induced combustion cannot observe the entire process of arc generation, evolution, and combustion activation, thus failing to meet the requirements for experimental and three-dimensional rotating sliding arc simulation. Specifically, the following technical defects exist: First, the electrodes of existing plasma burners cannot simultaneously possess conductivity and transparency, making it impossible to photograph the generated arc or limiting the photographic view to a single angle (i.e., axial direction). Due to overlapping fields of view, the true and complete morphology of the initial arc formation inside the burner cannot be observed. Second, when using transparent materials such as glass tubes to fabricate fuel pipes and other components to make the arc observable, optical distortion inevitably arises due to the non-planar structure of the electrodes or burner components, making it difficult to obtain a true, distortion-free arc morphology. Third, the flame generated by sliding arc plasma burners is unstable and exhibits large fluctuations, making it difficult to capture the flame morphology and free radical distribution using optical diagnostic instruments (such as cameras and laser diagnostics), thus failing to accurately describe the impact of plasma on combustion. Summary of the Invention

[0005] To address the shortcomings or improvement needs of existing technologies, this application provides an optical burner for visualizing the entire process of sliding arc plasma-assisted combustion. This aims to solve the problem that existing sliding arc plasma-excited burners cannot achieve full-angle, distortion-free visualization and monitoring of the entire process of sliding arc plasma generation, evolution, and excitation combustion.

[0006] This application provides an optical burner for visualizing the entire process of sliding arc plasma-assisted combustion, specifically including a visible furnace body, a low-obstruction discharge component, and an optical correction component, wherein: the bottom of the visible furnace body has an air inlet for air to be introduced, and a fuel pipe is provided inside for fuel to be introduced, and the upper part of the visible furnace body and the upper part of the fuel pipe are both made of transparent material to form an observation window;

[0007] The low-obstruction discharge assembly is located inside the fuel tube and includes, from bottom to top, an electrode rod, a high-voltage electrode, a spiral ground electrode, and a ground electrode terminal. One end of the electrode rod is connected to the high-voltage power supply, and the other end is connected to the high-voltage electrode. A swirling gas ring is fitted around the electrode rod to form swirling fuel. The spiral ground electrode is used to make the swirling fuel spiral upward and generate a rotating sliding arc. One end of the spiral ground electrode is close to the high-voltage electrode, and the other end is connected to the ground electrode terminal to achieve grounding. The spiral ground electrode is located in the observation window area.

[0008] The optical correction assembly includes an inner optical lens and an outer optical lens. The inner optical lens is located on the outside of the fuel pipe, and the outer optical lens is located on the outside of the visible furnace body. It is used to correct light distortion, thereby enabling observation of the entire process of the occurrence, evolution, and disappearance of the rotating sliding arc outside the furnace.

[0009] Compared with the prior art, the above-conceptual technical solution of this application introduces a spiral ground electrode and forms a swirling fuel with a swirling gas ring. This allows the light emitted by the electric arc to pass through the spiral gap while forming a rotating sliding arc. After the light distortion is corrected by the optical correction component, it is captured by the optical instrument, thereby realizing the observation of the entire process of the electric arc's occurrence, evolution, and disappearance from all angles without distortion.

[0010] As a further preferred embodiment, the interior of the visible furnace body is provided with a flame stabilizing component, which includes three layers of metal foam and one layer of glass beads. The first and second layers of metal foam are located on the upper and lower sides of the observation window, the third layer of metal foam is located above the air inlet, and the glass beads are located between the second and third layers of metal foam.

[0011] As a further preferred embodiment, the metal foam has a pore diameter of less than 100 μm and a porosity of 60% to 98%, and the thickness of the metal foam is 10 mm to 20 mm.

[0012] As a further preferred embodiment, the diameter of the high-voltage electrode at the end near the spiral ground electrode is 2mm to 3mm larger than the diameter at the end near the electrode rod.

[0013] As a further preferred embodiment, the visible furnace body includes a transparent furnace cylinder, a metal furnace cylinder, a bottom plate, a fixing plate, and an insulating base. The transparent furnace cylinder and the metal furnace cylinder are connected to form the side wall of the visible furnace body. The bottom plate is set at the bottom of the metal furnace cylinder and fixed by the fixing plate. The air inlet is opened on the bottom plate. The insulating base is set below the fixing plate and has a fuel inlet. The fuel inlet is connected to a fuel pipe to deliver fuel.

[0014] As a further preferred embodiment, an insulating quartz tube is sleeved on the outside of the electrode rod to support the swirling gas ring, and a fuel channel is formed between the insulating quartz tube and the fuel tube.

[0015] As a further preferred embodiment, the root-mean-square angle of divergence of the light rays emitted by the inner optical lens and the outer optical lens does not exceed 0.003°.

[0016] As a further preferred embodiment, the swirling air ring has 2 to 4 swirling holes.

[0017] As a further preferred embodiment, the inclination angle of the swirling orifice is 30° to 60°.

[0018] As a further preferred embodiment, the pitch of the spiral ground electrode is 3mm to 5mm, and the ratio of the pitch to the thickness of the spiral ground electrode is not less than 2.

[0019] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0020] 1. This application introduces a spiral ground electrode and combines it with a swirling gas ring to form swirling fuel. This allows the light emitted by the electric arc to pass through the spiral gap while forming a rotating sliding arc. By utilizing the special spiral structure of the spiral ground electrode, the efficient excitation combustion effect of the electric arc is preserved, and the electric arc is made observable. After the light distortion is corrected by the optical correction component, it can be captured by optical instruments without distortion. This enables the observation of the entire process of the electric arc's occurrence, evolution, and disappearance from all angles without distortion, thus solving the problem of electric arc visualization inside the burner.

[0021] 2. In particular, by setting a flame stabilizing component inside the visible furnace body, this application can solve the problems of unstable plasma flame and large flame oscillation amplitude, thereby obtaining a stable flame shape and free radical distribution;

[0022] 3. Furthermore, by optimizing the structure of the high-voltage electrode, this application can further ensure the high-quality generation of the rotating sliding arc. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of an optical burner that provides visualization of the entire sliding arc plasma-assisted combustion process according to an embodiment of this application;

[0024] Figure 2 yes Figure 1 C-section view;

[0025] Figure 3 yes Figure 1 A magnified view of a portion of region AA in the middle;

[0026] Figure 4 This is a schematic diagram of the fuel tube in the optical burner that provides visualization of the entire sliding arc plasma-assisted combustion process according to an embodiment of this application;

[0027] Figure 5 This is an optical path diagram of an optical burner that provides visualization of the entire process of sliding arc plasma-assisted combustion, as provided in the embodiments of this application.

[0028] Figure 6 This is a flowchart of the optical parameter optimization procedure for an optical burner that provides visualization of the entire process of sliding arc plasma-assisted combustion, as provided in this application embodiment.

[0029] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0030] 1: Insulating base; 1-1: Fuel inlet; 2: Sealing gasket; 3: Metal foam; 4: Metal furnace cylinder; 5: Glass bead; 6: Transparent furnace cylinder; 7: External optical lens; 8: Base plate; 8-1: Air inlet; 9: Fixing plate; 10: Sealing ring; 11: Transparent fuel pipe; 12: Internal optical lens; 13: Insulating quartz tube; 14: Swirl gas ring; 15: Spiral ground electrode; 16: Ground electrode terminal; 17: High voltage electrode; 18: Metal fuel pipe; 19: Electrode rod. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] like Figures 1-4 As shown, this application provides an optical burner for visualizing the entire process of sliding arc plasma-assisted combustion, specifically including a visible furnace body, a low-obstruction discharge component, and an optical correction component. The visible furnace body has an air inlet 8-1 at its bottom for air intake, and a fuel pipe inside for fuel intake. The outlet of the fuel pipe extends out of the visible furnace body. During operation, air and fuel are ejected from the upper end of the furnace body and the upper end of the fuel pipe, respectively, and then mixed and combusted. The upper part of the visible furnace body and the upper part of the fuel pipe are both made of transparent material to form observation windows.

[0033] The low-obstruction discharge assembly is located inside the fuel pipe and, from bottom to top, includes an electrode rod 19, a high-voltage electrode 17, and a specially designed low-obstruction spiral ground electrode 15. One end of the electrode rod 19 is connected to a high-voltage power supply, and the other end is threadedly connected to the high-voltage electrode 17, thereby providing high voltage to the high-voltage electrode 17. A swirling gas ring 14 is fitted around the electrode rod 19 to form swirling fuel. One end of the spiral ground electrode 15 is close to the high-voltage electrode 17, and the other end is threadedly connected to a ground electrode terminal 16 for grounding. Simultaneously, the spiral ground electrode 15 is located in the observation window area. The flowing fuel spirals upward along the spiral ground electrode 15 and generates a rotating sliding arc, thereby achieving conductivity and visibility, while also cooling the high-voltage electrode 17. During operation, after the high-voltage electrode 17 is connected to the high voltage, the shortest distance between it and the spiral ground electrode 15 (i.e., the lowest end of the spiral ground electrode 15) breaks down to generate an electric arc. One end of the electric arc spirals upward along the spiral ground electrode 15 under the action of the swirling fuel, and the electric arc is gradually lengthened. When the electric arc is lengthened to a certain length, it breaks down and re-breaks down at the shortest distance between the high-voltage electrode 17 and the spiral ground electrode 15 to form a new electric arc, and so on.

[0034] The optical correction assembly includes an inner optical lens 12 and an outer optical lens 7. The inner optical lens 12 is located on the outside of the fuel pipe and is used to correct the light distortion caused by the fuel pipe. The outer optical lens 7 is located on the outside of the visible furnace body and is used to correct the light distortion caused by the visible furnace body. The light emitted by the rotating sliding arc passes through the fuel pipe (distortion) → inner optical lens (correction) → transparent furnace cylinder (distortion) → outer optical lens (correction) in sequence to reach the external observation camera, thereby realizing the observation of the entire process of the occurrence, evolution and disappearance of the rotating sliding arc outside the furnace.

[0035] This application introduces a spiral ground electrode and, together with the swirling gas ring 14, forms swirling fuel. This allows the light emitted by the electric arc to pass through the spiral gap while a rotating sliding arc is being formed. The light distortion is then corrected by an optical correction component and captured by an optical instrument, thereby enabling the observation of the entire process of the electric arc's occurrence, evolution, and disappearance.

[0036] Furthermore, the visible furnace body and fuel pipe can be made entirely of high-temperature resistant transparent material, or a combination of transparent and metal materials. In a preferred embodiment of this application, the upper half of the visible furnace body is made of transparent material, and the lower half is made of metal material. Similarly, the upper half of the fuel pipe is a transparent fuel pipe 11, and the lower half is a metal fuel pipe 18. The transparent fuel pipe 11 has a stepped protrusion at its lower end, and the metal fuel pipe 18 has a stepped recess at its upper end; the two are connected to each other. The transparent fuel pipe 11 forms an observation window, and the metal fuel pipe 18 is used to fix the entire fuel pipe. The metal fuel pipe 18 and the transparent fuel pipe 11 are fitted with a clearance (preferably with a tolerance grade of H8 / f7), allowing for the insertion of a sealant to prevent air leakage.

[0037] Furthermore, the interior of the visible furnace body is equipped with a flame stabilizing component, which consists of three layers of metal foam 3 and one layer of glass beads 5. The first and second layers of metal foam 3 are located on the upper and lower sides of the observation window, the third layer of metal foam 3 is located above the air inlet 8-1, and the glass beads 5 are located between the second and third layers of metal foam 3. During operation, air is introduced through the air inlet 8-1 on the bottom plate, and then passes through the metal foam 3 and glass beads 5 in sequence. This makes the airflow uniform and stable. At the same time, the fuel generates active substances such as electrons, ions, and free radicals under the action of the spiral sliding arc, which can improve combustion. The airflow carrying active substances is ejected from the fuel pipe and comes into contact with the uniform airflow ejected from the flame stabilizing component, thereby forming a stable diffused flame.

[0038] Furthermore, the swirling gas ring 14 has 2 to 4 swirling holes with an inclination angle of 30° to 60°. The number of swirling holes and their inclination angle are coordinated to keep the rotational speed of the sliding arc within a suitable range of 10 r / s to 100 r / s. Excessive rotational speed of the sliding arc can easily cause it to extinguish, while insufficient rotational speed results in low fuel cracking efficiency. Simultaneously, the pitch of the helical ground electrode (3 mm to 5 mm) needs to be coordinated with the rotational speed of the sliding arc to allow it to extend to a longer length in the shortest possible time (the longer the sliding arc, the more active particles, and the better the effect).

[0039] Furthermore, the pore diameter of the metal foam 3 is less than 100 μm and the porosity is 60%–98%, while the thickness of the metal foam 3 is 10 mm–20 mm, thus ensuring uniform airflow. If the thickness of the metal foam 3 is too large or too small, it will lead to uneven airflow.

[0040] Furthermore, the diameter of the end of the high-voltage electrode 17 near the spiral ground electrode 15 (head) is 2mm to 3mm larger than the diameter of the end near the electrode rod 19 (root). The head and root are connected by a conical transition. This allows a high-velocity swirling airflow to be generated in the annular gap between the head of the high-voltage electrode 17 and the fuel pipe, even if the fuel gas flow rate is small, which provides sufficient power to rotate the electric arc.

[0041] The high-voltage electrode 17 is made of high-temperature resistant metal. The spiral ground electrode 15 consists of an upper metal ring and a lower spiral metal strip. The metal ring is made of high-temperature resistant metal, and its spiral section has a rectangular or circular cross-section with a thickness or diameter between 0.5 and 2 mm. This avoids the electrode from deforming due to heat if the cross-section is too small, and also avoids the cross-section from blocking the arc if it is too large. The pitch is 3 mm to 5 mm. If the pitch is too small, it will block the arc; if the pitch is too large, it will reduce the number of arc rotations and affect efficiency. The ratio of the pitch to the thickness of the spiral ground electrode (i.e., the duty cycle) is not less than 2. If the duty cycle is too small, it will block the arc. The number of rotations is 5 to 8. If the number of rotations is too small, it will reduce the number of arc rotations and affect efficiency; if the number of rotations is too large, it will increase the length of the spiral ground electrode and occupy space. The arc will generally break after 5 to 8 rotations. The outer diameter of the spiral ground electrode 15 is 1mm to 2mm larger than the head diameter of the high-voltage electrode 17. If the outer diameter is too small, the electrode gap will be too large, reducing the flow rate and affecting the normal sliding of the electric arc. If it is too large, the electric arc will be blown out, affecting efficiency. In addition, the vertical distance from the bottom of the spiral ground electrode 15 to the top of the high-voltage electrode 17 does not exceed 2mm. If it is too large, the gas will not be easily broken down, and it will not be easy to form an electric arc. The upper metal ring of the spiral ground electrode 15 has a threaded hole on its side, which can be used in conjunction with the round hole on the side of the transparent fuel tube 11 to insert the ground electrode terminal 16 from the side of the transparent fuel tube 11. At the same time, the upper metal ring can be locked at the stepped hole of the transparent fuel tube 11 to position the spiral ground electrode 15. Due to its special spiral strip structure, the lower spiral metal strip can allow the light emitted by the electric arc to pass through the spiral gap while generating a rotating sliding arc, so that it can be captured by optical instruments.

[0042] The electrode rod 19 is a threaded rod made of 304 stainless steel. The ground electrode terminal 16 is also a threaded rod with a diameter of 1 mm and made of 304 stainless steel. The ground electrode terminal 16 can be screwed into the threaded hole of the annular metal strip of the spiral ground electrode 15 through the small hole on the side of the transparent fuel tube 11. The swirling gas ring 14 is made of polytetrafluoroethylene and has an interference fit with the metal fuel tube 18. The number of swirling holes is 2 to 4, the tilt angle of the swirling holes is preferably 30° to 60°, and the diameter of the swirling holes is 0.5 mm to 1 mm. The inner diameter of the insulating quartz tube 13 is the same as the outer diameter of the electrode rod 19, which is 4 mm to 6 mm. The outer diameter of the insulating quartz tube 13 should ensure that it does not block the swirling gas holes on the swirling gas ring 14.

[0043] The inner diameter of the transparent fuel tube 11 is the same as the outer diameter of the spiral ground electrode 15 and is not less than 10 mm. The transparent fuel tube 11 has a small hole on its side, into which the ground electrode terminal 16 can be inserted.

[0044] Furthermore, the visible furnace body includes a transparent furnace cylinder 6, a metal furnace cylinder 4, a base plate 8, a fixing plate 9, and an insulating seat 1. The transparent furnace cylinder 6 and the metal furnace cylinder 4 are connected to form the side wall of the visible furnace body. The metal furnace cylinder 4 has a stepped recess on top, and the transparent furnace cylinder 6 has a stepped protrusion on the bottom. The two are connected to each other to achieve a clearance fit (preferably with a tolerance grade of H8 / f7), and a sealant can be inserted into the gap to prevent air leakage. The base plate 8 is set at the bottom of the metal furnace cylinder 4 and welded to the metal furnace cylinder 4 to ensure the strength and sealing of the visible furnace body. The fixing plate 9 is used to... For fixation, an air inlet 8-1 is provided on the base plate 8, and the metal furnace cylinder 4 is placed in the stepped recess on the base plate 8. The lower end of the fuel pipe is interference-fitted with the center hole of the fixing plate 9 (preferably with a tolerance grade of H7 / p6) to ensure the coaxiality of the fuel pipe and the center hole of the fixing plate 9 and to effectively prevent air leakage. The fixing plate 9 has four stepped holes for mounting bolts, which are used to fix and connect to the base plate 8 and the insulating seat 1 respectively. The insulating seat 1 is located below the fixing plate 9 and has a fuel inlet 1-1, which communicates with the fuel pipe to supply fuel. The base plate 8 and the fixing plate 9 are sealed with a sealing gasket 2, and the fixing plate 9 and the insulating seat 1 are sealed with a sealing ring 10. The transparent fuel pipe 11 and the transparent furnace cylinder 6 are both made of high-temperature resistant optical transparent material, preferably transparent ceramic (transmittance greater than 95%, melting point greater than 2300K, refractive index 1.76-2.64).

[0045] Furthermore, an insulating quartz tube 13 is fitted over the electrode rod 19. The bottom of the insulating quartz tube 13 contacts the bottom of the central hole of the insulating base 1, supporting the swirling gas ring 14. A fuel channel is formed between the insulating quartz tube 13 and the fuel tube. During operation, fuel is introduced from the fuel inlet 1-1, then rises along the annular gap formed by the fuel tube and the insulating quartz tube 13, and passes through the swirling gas ring 14 to form a swirling flow. When the fuel tube consists of a transparent fuel tube 11 and a metal fuel tube 18, the insulating quartz tube 13 is fitted over the metal fuel tube 18 to prevent energy loss caused by discharge between the electrode rod 19 and the metal fuel tube 18.

[0046] Furthermore, by optimizing the shape, thickness, and placement of the inner optical lens 12 and the outer optical lens 7, the root mean square angle of the emitted light divergence does not exceed 0.003°. The parameter optimization method for the inner optical lens 12 and the outer optical lens 7 is as follows: the light emitted from the rotating sliding arc is distorted after passing through the transparent fuel tube 11. Then, a set of geometric parameters (inner diameter, outer diameter, thickness) for the inner optical lens 12 is calculated using software. If this set of geometric parameters satisfies the condition that 80% of the light rays are essentially parallel, that set of parameters is used; otherwise, iterative calculations continue until it is satisfied. The method for determining the geometric parameters of the outer optical lens 7 is the same as that for the inner optical lens. The optical path diagram and program flowchart are shown below. Figure 5 , Figure 6 .

[0047] Specifically: The deflection angle of light from gas to transparent material or from transparent material to gas is calculated using Snell's law, i.e., equation (1).

[0048] (1)

[0049] in, n 1 represents the refractive index of the medium in which the incident ray is contained. n 2 represents the refractive index of the medium in which the emitted light ray is emitted. θ 1 is the angle of incidence. θ 2 is the emission angle;

[0050] The method for determining the geometric parameters of optical lenses (inner diameter r1, outer diameter r2, thickness L1, inner diameter R1, outer diameter R2, and thickness L2) is as follows: First, give a set of r1, r2, L1, R1, R2, and L2. Then, use Snell's law to calculate whether the root mean square (RMS) of the divergence angle of the light rays emitted from the 12 inner optical lenses and the 6 outer optical lenses exceeds 0.003°. If it does not exceed 0.003°, the geometric parameters of the lens set are considered appropriate. Otherwise, adjust the set of parameters until the condition that the root mean square (RMS) of the divergence angle of the light rays exceeds 0.003° is met.

[0051] The operation method of the optical burner for visualizing the entire process of sliding arc plasma-assisted combustion provided in this application is as follows:

[0052] 1) Introduce fuel and air into fuel inlet 1-1 and air inlet 8-1 respectively, and achieve the set flow rates respectively;

[0053] 2) Turn on the plasma power supply to reach the set power, break down and activate the fuel in the transparent fuel tube 11, and the fuel is ejected and comes into contact with the air for combustion;

[0054] 3) Use two external observation cameras to photograph the electric arc from above the transparent fuel tube 11 and from the front of the external optical lens 7, respectively;

[0055] 4) Use lasers or other optical equipment to diagnose flames.

[0056] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0057] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0059] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical burner for visualizing the entire process of sliding arc plasma-assisted combustion, characterized in that, It includes a visible furnace body, a low-obstruction discharge assembly, and an optical correction assembly, wherein: the bottom of the visible furnace body has an air inlet (8-1) for air to be introduced, and a fuel pipe is provided inside for fuel to be introduced; and the upper part of the visible furnace body and the upper part of the fuel pipe are both made of transparent material to form an observation window. The low-obstruction discharge assembly is located inside the fuel tube and includes, from bottom to top, an electrode rod (19), a high-voltage electrode (17), a spiral ground electrode (15), and a ground electrode terminal (16). One end of the electrode rod (19) is connected to a high-voltage power supply, and the other end is connected to the high-voltage electrode (17). A swirling gas ring (14) is fitted around the electrode rod (19) to form swirling fuel. The spiral ground electrode (15) is used to make the swirling fuel spiral upward and generate a rotating sliding arc. One end of the spiral ground electrode (15) is close to the high-voltage electrode (17), and the other end is connected to the ground electrode terminal (16) to achieve grounding. The spiral ground electrode (15) is located in the observation window area. The optical correction assembly includes an inner optical lens (12) and an outer optical lens (7). The inner optical lens (12) is located on the outside of the fuel pipe, and the outer optical lens (7) is located on the outside of the visible furnace body. It is used to correct light distortion and thus realize the observation of the entire process of the occurrence, evolution and disappearance of the rotating sliding arc outside the furnace.

2. The optical burner as claimed in claim 1, characterized in that, The interior of the visible furnace body is equipped with a flame stabilizing component, which includes three layers of metal foam (3) and one layer of glass beads (5). The first layer of metal foam (3) and the second layer of metal foam (3) are located on the upper and lower sides of the observation window, the third layer of metal foam (3) is located above the air inlet (8-1), and the glass beads (5) are located between the second layer of metal foam (3) and the third layer of metal foam (3).

3. The optical burner as described in claim 2, characterized in that, The metal foam (3) has a pore diameter of less than 100 μm and a porosity of 60% to 98%, and the thickness of the metal foam (3) is 10 mm to 20 mm.

4. The optical burner as claimed in claim 1, characterized in that, The diameter of the high-voltage electrode (17) near the spiral ground electrode (15) is 2 mm to 3 mm larger than the diameter of the end near the electrode rod (19).

5. The optical burner as claimed in claim 1, characterized in that, The visible furnace body includes a transparent furnace cylinder (6), a metal furnace cylinder (4), a bottom plate (8), a fixing plate (9), and an insulating seat (1). The transparent furnace cylinder (6) is connected to the metal furnace cylinder (4) to form the side wall of the visible furnace body. The bottom plate (8) is set at the bottom of the metal furnace cylinder (4) and fixed by the fixing plate (9). The air inlet (8-1) is opened on the bottom plate (8). The insulating seat (1) is set below the fixing plate (9). The insulating seat (1) is provided with a fuel inlet (1-1). The fuel inlet (1-1) is connected to the fuel pipe to deliver fuel.

6. The optical burner as claimed in claim 1, characterized in that, An insulating quartz tube (13) is fitted around the electrode rod (19) to support the swirling gas ring (14), and a fuel channel is formed between the insulating quartz tube (13) and the fuel tube.

7. The optical burner as claimed in claim 1, characterized in that, The root mean square angle of divergence of the light emitted from the inner optical lens (12) and the outer optical lens (7) does not exceed 0.003°.

8. The optical burner as claimed in claim 1, characterized in that, The swirling air ring (14) has 2 to 4 swirling holes.

9. The optical burner as claimed in claim 8, characterized in that, The inclination angle of the vortex orifice is 30° to 60°.

10. The optical burner according to any one of claims 1 to 9, characterized in that, The pitch of the spiral ground electrode (15) is 3mm to 5mm, and the ratio of the pitch to the thickness of the spiral ground electrode (15) is not less than 2.

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