A magnetic control double-arc reverse motion type eddy current generating device and design method

Abstract

This invention discloses a magnetically controlled dual-arc reverse motion eddy current generator and its design method, comprising a magnet, an insulating medium, and an electrode assembly. The electrode assembly is embedded within the insulating medium, with the lower surface of the insulating medium adhering to the surface of the magnet. The electrode assembly includes an anode, a first electrode adjacent to the anode, a cathode, and a second electrode adjacent to the cathode, arranged in an array. The four electrodes are embedded within the insulating medium, with their upper surfaces flush with the surface of the insulating medium. This invention can effectively delay or suppress boundary layer flow separation in aerodynamics. It can be activated and deactivated according to aircraft operating conditions, and the eddy current intensity and arc speed can be adjusted according to flow control needs, achieving real-time active and precise control. By changing the electrode length, a certain degree of wall drag reduction can be achieved by utilizing the arc's spanwise motion while generating eddies.

Description

Technical Field

[0001] This invention relates to the field of plasma flow control, specifically to a magnetically controlled dual-arc reverse motion eddy current generator and its design method. Background Technology

[0002] Vortex generators are a common means of controlling aerodynamic interferences such as shock waves / boundary layer disturbances and flow separation in aerodynamics. The high-energy vortices generated by the vortex generators are fully mixed with the downstream boundary layer flow field, allowing the boundary layer flow field in the adverse pressure gradient to gain additional energy and continue to adhere to the surface of the aircraft without separating, thereby achieving the effect of increasing lift and reducing drag.

[0003] Currently, commonly used eddy current generators are divided into passive and active types. Passive eddy current generators are installed at specific locations on the aircraft surface. Under certain conditions, they can delay boundary layer separation, thereby increasing lift and reducing drag. However, under other specific operating conditions, they may increase additional drag. Active eddy current generators can adjust their parameters according to changes in aircraft operating conditions and flow states. They can achieve increased lift and reduced drag under specific operating conditions without increasing additional flight drag under other operating conditions, making them a very flexible active flow control strategy. Among them, plasma-based eddy current generators are typical active eddy current generators, and they have been widely studied and applied due to their simple structure, flexible operation, low power consumption, and rapid response. For example, "Plasma Eddy Current Generator, CN103213675B" generates flow vortices by adjusting the angle between the induced jet and the controlled incoming flow through a plasma exciter, while "Dielectric Barrier Discharge Plasma Eddy Current Generator, CN203081914U" generates eddy currents by mixing a plasma-synthesized jet with the controlled incoming flow. These types of vortex generators all generate vortices by mixing the jets produced by one or more plasma exciters with the mainstream. The exciters themselves do not directly generate vortices, which leads to problems such as weak momentum exchange with the controlled incoming flow and unsatisfactory control effects. Summary of the Invention

[0004] The purpose of this invention is to design an electrode structure capable of generating a double electric arc, and to use the Lorentz force generated by the magnetic field of a permanent magnet to control the reverse motion of the electric arc to generate eddy currents.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A magnetically controlled dual-arc reverse motion eddy current generator includes a magnet, an insulating medium, and an electrode assembly. The electrode assembly is embedded in the insulating medium, and the lower surface of the insulating medium is attached to the surface of the magnet.

[0007] The electrode assembly includes an anode, a first electrode plate adjacent to the anode, a cathode, and a second electrode plate adjacent to the cathode. The four electrodes are arranged in an array, and the first and second electrode plates are connected.

[0008] Four electrodes are embedded in an insulating medium, with the upper surface of the electrodes flush with the surface of the insulating medium.

[0009] The anode has protruding arc-starting points on the side opposite to the first electrode plate, and the cathode has protruding arc-starting points on the side opposite to the second electrode plate.

[0010] The anode and the protruding arc-starting point on the first electrode sheet are positioned opposite each other, and the two do not contact each other;

[0011] The cathode and the protruding arc-starting point on the second electrode are positioned opposite each other, and the two do not contact each other.

[0012] The magnet comprises, from the inside out, a permanent magnet, a magnetic shielding layer, and an insulating layer. The permanent magnet, except for its upper surface, is encapsulated within the magnetic shielding layer and the insulating layer.

[0013] One end face of the magnet is open, and the permanent magnet at the opening is attached to the surface of the insulating medium.

[0014] A design method for a magnetically controlled dual-arc reverse motion eddy current generator includes the following steps:

[0015] S1: Design four independent planar electrodes, which are arranged in an array, wherein:

[0016] The cathode and anode are arranged side by side, and the first electrode plate and the second electrode plate are arranged side by side, with the first electrode plate and the second electrode plate located on the same side of the cathode and anode;

[0017] S2: Each electrode is provided with a protruding arc-starting point. Taking the center point of the distribution of the four electrodes as the reference, the arc-starting point is set at the far end of the electrode. From the arc-starting point to the center point, the electrodes are distributed in an extended or parallel state.

[0018] S3: Define the distance between the anode and the two protruding arc-starting points on the first electrode plate as... The distance between the two protruding arc-starting points on the anode and cathode is The relative distance between the anode and cathode sides is The minimum distance between the anode and the first electrode plate, excluding the arc initiation point, is The relative positions of the four electrodes satisfy the following mathematical relationship: .

[0019] The Lorentz force generated by the magnetic field of the permanent magnet on the electric arc is The electric arc is subjected to the Lorentz force generated by the magnetic field of the electrodes themselves. The calculation formula is as follows: , ,in: This refers to the Z-direction magnetic field component generated by the permanent magnet. and These are the two components of the magnetic field generated by the electromagnetic induction of the discharge electrode plates. and These are the two components of the arc current. This is the length of the electric arc.

[0020] The approximate formula for calculating the air resistance experienced by the electric arc is: ,in, This is the aerodynamic drag coefficient. For charge density, The speed of the electric arc. The diameter of the discharge arc.

[0021] The axial force caused by the change in gas pressure is:

[0022] The entire process of the electric arc from its generation to its dissipation must meet the following conditions:

[0023]

[0024] in: For arc quality, , This refers to the acceleration during the electric arc's motion.

[0025] In the above technical solution, the eddy current generator can be driven by two different power sources.

[0026] When the driving power supply is a high-voltage pulse power supply, the electrode structure dimensions satisfy the following mathematical relationship: , This represents the distance the electric arc travels from its generation to its dissipation.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] This invention can effectively delay or suppress boundary layer flow separation in aerodynamics;

[0029] This invention uses a high-voltage DC / pulse power supply to drive the arc discharge, and the Lorentz force generated by the permanent magnet array drives the arc to move in the opposite direction. It does not require an additional air source and the control system is simple.

[0030] The electrode assembly of the present invention can be processed into any curved surface and attached to the surface of the aircraft. It has the characteristics of simple structure, easy installation, low power consumption, fast response, and no change to the original shape of the aircraft.

[0031] This invention can be turned on and off according to the operating conditions of the aircraft, and can adjust the eddy current intensity and arc motion speed according to the needs of flow control, so as to achieve real-time active control and precise control.

[0032] When the electrode assembly of the present invention is placed along the spanwise direction, the wall drag reduction effect can be achieved to a certain extent by changing the electrode length, generating eddy currents and utilizing the arc moving in the spanwise direction. Attached Figure Description

[0033] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0034] Figure 1 This is a schematic diagram of the overall structure of this embodiment;

[0035] Figure 2 This is a schematic diagram of the first possible electrode layout;

[0036] Figure 3 This is a schematic diagram of the second electrode layout;

[0037] Figure 4 This is a schematic diagram of the third electrode layout.

[0038] Figure 5 This is a schematic diagram of the magnet module structure;

[0039] Figure 6 This is a schematic diagram of a high-voltage DC power supply driving the reverse motion of two electric arcs;

[0040] Figure 7 This is a schematic diagram of a high-voltage pulse power supply driving the reverse motion of two electric arcs;

[0041] Wherein: 1 is the power supply, 2 is the magnet module, 21 is the permanent magnet, 22 is the shielding layer, 23 is the insulating layer, 3 is the electrode module, 31 is the anode, 32 is the first electrode plate, 33 is the second electrode plate, 34 is the cathode, and 35 is the insulating medium. Detailed Implementation

[0042] All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.

[0043] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0044] like Figure 1 As shown, the overall device in this embodiment consists of a power supply and drive circuit, a magnet module, and an electrode module. The power supply can be either a high-voltage DC power supply or a high-voltage pulse power supply. The two different power supplies can drive the electric arc in different ways. The magnet module is attached to the electrode module.

[0045] like Figure 2 As shown, in this embodiment, the structure of the electrode module 3 includes an electrode and an insulating medium 35, wherein the electrode is embedded in the insulating medium 35, and the upper surface of the electrode is flush with the upper surface of the insulating medium 35.

[0046] In this embodiment, the thickness of the electrode sheet is 0.1mm~2mm, the width of the electrode sheet is 0.2mm~10mm, and the length of the electrode sheet can be selected according to the actual application. The protrusion distance of the arc-starting point on the electrode is 0.1mm~5mm. The electrode sheet can be made of materials such as tungsten, copper, or tungsten-copper alloy. The distance between the protrusion of the arc-starting point of the anode 31 and the first electrode sheet 32 ​​is... The distance between the cathode 34 and the protruding arc-starting point of the second electrode plate 2 is The relative distance between the sides of the anode 31 and the cathode 32 is ,exist More than 2 times The mathematical relationship, excluding the arc initiation point, is that the minimum distance between the anode 31 and the first electrode plate 32 is... The minimum distance between the cathode 34 and the second electrode plate 33, excluding the arc ignition point, is ,exist Greater than The mathematical relationship. The distance between the protruding arc-starting points of anode 31 and cathode 34 is... The distance between the protruding arc initiation points of the first electrode plate 32 and the second electrode plate 33 is ,exist Greater than The mathematical relationship.

[0047] like Figure 5As shown, in this embodiment, the magnet module 2 comprises three layers from the inside out. The innermost layer is a permanent magnet 21, which can be a neodymium iron boron magnet. The middle layer is a shielding layer 22, made of an open-type high-permeability material with a thickness of 0.1mm to 3mm. The outermost layer is a non-metallic high-temperature insulating layer 23 with a thickness of 0.1mm to 2mm. The layers are sealed together with high-temperature silicone adhesive, with a spacing of 0.1mm to 0.5mm between layers. The neodymium iron boron magnet can be a single magnet or multiple permanent magnets arranged in a specific manner to form a single-sided magnetic field enhancement array. The high-permeability material can be permalloy, and the non-metallic high-temperature insulating medium can be PPS plastic, boron nitride ceramic, etc.

[0048] This embodiment has two operating modes. When the power supply is a high-voltage DC power supply, the process of generating eddy currents includes three stages: double arc generation, double arc reverse motion, and double arc merging. Figure 6 As shown, specifically:

[0049] Dual arc generation stage: The air at the protruding arc initiation points on the two sets of electrodes is broken down by high voltage, and an electric arc plasma is formed at the moment of discharge. The gas is heated, and the energy deposition induces a shock wave.

[0050] The reverse motion phase of the dual arcs: Due to the relatively low initial velocity of the arcs during generation, the aerodynamic drag they experience is less than the Lorentz force, causing the dual arcs to accelerate in the reverse direction along the electrode surface towards the center of the electrode plate array. Simultaneously, the heated gas near each arc channel rapidly expands towards the main flow, gradually evolving into a vortex-shaped jet structure under the influence of the incoming flow's compressibility, and moves along the electrode surface with the arcs towards the center of the electrode plate array. Furthermore, a depressurization zone forms behind the hot gas zone, leading to the intake of surrounding gas. Therefore, after the formation of the vortex-shaped main jet, a secondary flow with comparable velocity is generated at the rear of the arc. As the arc velocity increases, the aerodynamic drag and Lorentz force gradually reach equilibrium, and the dual arcs enter a near-uniform reverse motion phase. The duration of this phase is closely related to the electrode structure dimension d4; the larger d4 is, the longer the near-uniform motion time, and vice versa.

[0051] The merging and dissipation stage of the two electric arcs: at the moment the two electric arcs meet, the anode and cathode of the electrode plate array are connected, the two electric arcs merge into one electric arc, and then spread to the outside of the electrode plate array under the action of Lorentz force, and finally are broken by the action of Lorentz force, and re-enter the double electric arc generation stage.

[0052] For a high-voltage DC power supply dual-arc reverse motion eddy current generator, the electrode structure dimensions can be designed according to the actual application scenario, based on the above basic dimensional relationships (i.e., d2>2d1, d4>d2, d3>d1).

[0053] When the power supply is a high-voltage pulse power supply, the process of generating eddy currents includes two stages: the generation of a double electric arc and the reverse motion of the double electric arc, such as... Figure 7 As shown, specifically:

[0054] Dual arc generation stage: The air at the protruding arc initiation points on the two sets of electrodes is broken down by high voltage, and an electric arc plasma is formed at the moment of discharge. The gas is heated, and the energy deposition induces a shock wave.

[0055] The reverse motion phase of the double arcs: Due to the large pulse discharge current at the moment of arc generation, the Lorentz force on the double arcs is greater than the aerodynamic drag, resulting in a large acceleration. This causes the double arcs to accelerate in the reverse direction along the electrode surface towards the center of the electrode plate array. As the discharge current weakens, the Lorentz force on the double arcs becomes less than the aerodynamic drag, and the double arcs enter the deceleration phase. As the discharge current further weakens to zero, the double arcs dissipate before meeting and re-enter the double arc generation phase. During the arc motion, the heated gas near each arc channel rapidly expands towards the main flow, gradually evolving into a vortex-shaped jet structure under the influence of the compressibility of the incoming flow, and moves along the electrode surface with the arc towards the center of the electrode plate array. In addition, a depressurization zone is formed behind the hot gas zone, leading to the intake of surrounding gas. Therefore, after the formation of the vortex-shaped main jet, a secondary flow with a similar velocity is generated at the rear of the arc. After the current terminates, the movement of the density disturbance slows down, the opposing vortices move towards each other, and gradually deform and elongate in the vertical direction within the collision area, forming a flow similar to a wall jet structure, which propagates from the collision area along the wall normal direction.

[0056] For a high-voltage pulse power supply dual-arc reverse motion eddy current generator, its electrode structure dimensions, in addition to satisfying the above basic dimensional relationships (i.e., d2 > 2d1, d4 > d2, d3 > d1), must also satisfy... ,in The distance the electric arc travels from its generation to its dissipation is calculated using the force formula during the arc's motion and the discharge parameters of the high-voltage pulse power supply.

[0057] The electrodes in this embodiment can also be as follows: Figure 3 The electrodes are distributed in a pattern, with the four electrodes extending from both ends towards the middle. For example... Figure 4 As shown, the anode and cathode are arranged side by side in parallel, while the first and second electrode plates are distributed in an extended manner on one side of the cathode and anode. That is, the arc-starting point is located at the far end of the electrode, and from the far end to the center, the electrodes are parallel or extended to each other, and cannot be distributed in a contracted state.

[0058] Example 1

[0059] A single rectangular permanent magnet is used to construct the permanent magnet control module. The permanent magnet has a size of 10mm (10mm (80mm)) and generates a magnetic field of approximately 0.3T on the electrode surface of the eddy current generator. The anode, cathode, first electrode plate, and second electrode plate are arranged in parallel. The parallel spacing between the anode and the first electrode plate is 7mm, the parallel spacing between the cathode and the second electrode plate is 7mm, the spacing between the protruding arc-initiating points of the anode and the first electrode plate is 1mm, and the spacing between the protruding arc-initiating points of the cathode and the second electrode plate is 1mm. A high-voltage pulse power supply drives the dual arcs to move in reverse. The peak discharge current of the electrodes in air can reach 50A, the discharge pulse period is 130μs, the peak discharge power can reach 7kW, and the peak arc velocity reaches 210m / s. After the arc dissipates, the reverse gas vortices move towards each other and gradually deform and elongate in the vertical direction within the collision area, forming a flow structure similar to a wall jet.

[0060] Example 2

[0061] Driven by a high-voltage DC power supply, the anode, cathode, first electrode plate, and second electrode plate are arranged in parallel. The distance between the protruding arc-initiating points of the anode and the first electrode plate is 2 mm, the distance between the protruding arc-initiating points of the cathode and the second electrode plate is 2 mm, the lateral relative distance between the anode and the cathode is 10 mm, the parallel distance between the anode and the first electrode plate is 7 mm, and the parallel distance between the cathode and the second electrode plate is 7 mm. The distance between the protruding arc-initiating points of the anode and the cathode is 30 mm, and the distance between the protruding arc-initiating points of the first electrode plate and the second electrode plate is 30 mm. A permanent magnet control module is constructed using four cuboid permanent magnets, each with a size of 8 mm², which generate a magnetic field of approximately 0.3 T on the electrode surface of the eddy current generator.

[0062] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A magnetically controlled dual-arc reverse motion eddy current generator, characterized in that: It includes a magnet, an insulating medium, and an electrode assembly, wherein the electrode assembly is embedded in the insulating medium, and the lower surface of the insulating medium is attached to the surface of the magnet. The electrode assembly includes an anode, a first electrode plate adjacent to the anode, a cathode, and a second electrode plate adjacent to the cathode. The four electrodes are arranged in an array, and the first and second electrode plates are connected. The anode has protruding arc-starting points on its side opposite to the first electrode plate, and the cathode has protruding arc-starting points on its side opposite to the second electrode plate. Four electrodes are embedded in an insulating medium, with the upper surface of the electrodes flush with the surface of the insulating medium.

2. The magnetically controlled dual-arc reverse motion eddy current generator according to claim 1, characterized in that: The anode and the protruding arc-starting point on the first electrode sheet are positioned opposite each other, and the two do not contact each other; The cathode and the protruding arc-starting point on the second electrode are positioned opposite each other, and the two do not contact each other.

3. The magnetically controlled dual-arc reverse motion eddy current generator according to claim 1, characterized in that: The magnet comprises, from the inside out, a permanent magnet, a magnetic shielding layer, and an insulating layer. The permanent magnet, except for its upper surface, is encapsulated within the magnetic shielding layer and the insulating layer.

4. The magnetically controlled dual-arc reverse motion eddy current generator according to claim 3, characterized in that: One end face of the magnet is open, and the permanent magnet at the opening is attached to the lower surface of the insulating medium.

5. A design method for a magnetically controlled dual-arc reverse motion eddy current generator, characterized in that... Includes the following steps: S1: Design four independent planar electrodes, which are arranged in an array, wherein: The cathode and anode are arranged side by side, and the first electrode plate and the second electrode plate are arranged side by side, with the first electrode plate and the second electrode plate located on the same side of the cathode and anode; S2: Each electrode is provided with a protruding arc-starting point. Taking the center point of the distribution of the four electrodes as the reference, the arc-starting point is set at the far end of the electrode. From the arc-starting point to the center point, the electrodes are distributed in an extended or parallel state. S3: Define the distance between the anode and the two protruding arc-starting points on the first electrode plate as... The distance between the two protruding arc-starting points on the anode and cathode is The relative distance between the anode and cathode sides is The minimum distance between the anode and the first electrode plate, excluding the arc initiation point, is The relative positions of the four electrodes satisfy the corresponding mathematical relationship: .

6. The design method of a magnetically controlled dual-arc reverse motion eddy current generator according to claim 5, characterized in that: When the driving power supply is a high-voltage pulse power supply, the electrode structure dimensions satisfy the following mathematical relationship: , This represents the distance the electric arc travels from its generation to its dissipation.

7. The design method of a magnetically controlled dual-arc reverse motion eddy current generator according to claim 5, characterized in that... The motion of a discharge arc from its generation to its dissipation must meet the following conditions: ， in: For arc quality, This refers to the Lorentz force experienced by the electric arc as it moves within the magnetic field of the permanent magnet. The Lorentz force is generated by the magnetic field of the electrode itself. The axial force is caused by changes in gas pressure. The air resistance encountered by the electric arc motion, This refers to the acceleration during the electric arc's motion.

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