A magnetic control plasma based eddy current generating device and design method

Abstract

This invention discloses an eddy current generator and its design method based on magnetron plasma. The device includes an insulating shell with an annular groove on one end face. An integral cathode is embedded in the annular groove. A through-hole is provided at the center of the annular groove, and an anode is placed in the through-hole. A cylindrical magnet is placed inside the insulating shell. The magnet has a hollow structure extending through both ends along its axial direction. The hollow structure overlaps axially with the through-hole of the insulating shell. The upper surface of the cathode, the end face of the insulating shell with the embedded cathode, and the upper surface of the anode are flush with each other. A power line passes through the insulating shell from the other end and connects to the anode and cathode. When active control is required, this invention can achieve active flow control by activating the device. When active control is not required, it consumes no energy, does not change the original flow characteristics of the aircraft, and does not increase the control complexity of the original aircraft.

Description

Technical Field

[0001] This invention belongs to the field of flow control technology, specifically relating to an eddy current generator and design method based on magnetron plasma, which can be used for active flow separation control of aircraft. Background Technology

[0002] Vortex generators are commonly used flow control devices in the aerospace field, achieving lift enhancement and drag reduction by adjusting boundary layer flow separation. Currently, commonly used vortex generators can be divided into passive and active types. Passive vortex generators have a simple structure, require no additional energy, and are installed at specific locations on the aircraft to modify its shape, thereby improving flow separation under specific operating conditions and achieving lift enhancement and drag reduction. However, their flow control effect deviates when the aircraft's attitude and Mach number change, and they may even increase drag. Active vortex generators can be flexibly controlled according to the aircraft's motion conditions, achieving lift enhancement and drag reduction under multiple motion conditions. These mainly include dynamic vortex generators, vortex jets, and plasma vortex generators. Dynamic vortex generators achieve active control by changing the local shape of the aircraft through intelligent drive devices, while vortex jets achieve active control by generating a jet through an additional gas source. These two types of active vortex generators have more complex structures and add extra weight. Plasma vortex generators achieve active control by generating plasma to change the original flow characteristics of the aircraft, and are characterized by small size, light weight, and flexible control. However, current plasma eddy current generators suffer from drawbacks such as small eddy current disturbances and unsatisfactory control effects. Two-electrode or multi-electrode arrays place higher demands on the thermal protection performance of the spacecraft's materials. Long-term discharge at the same location can easily ablate the electrodes. Furthermore, the flow eddy current disturbances generated by the interaction between the thermal effect of electrode discharge and the free flow in this type of eddy current generator are small and cannot be actively controlled. In magnetic rotating plasma eddy current devices with holes, the holes generate additional shock waves, increasing the complexity of active control and affecting its effectiveness. Summary of the Invention

[0003] The purpose of this invention is to design an eddy current generator based on magnetocontrolled plasma. By designing the relative structure of the anode, cathode, and cylindrical magnet, the Lorentz force generated by the magnet controls the rotation of the plasma to generate eddy currents. When active control is required, the device can be activated to achieve active flow control. When active control is not required, it consumes no energy, does not change the original flow characteristics of the aircraft, and does not increase the control complexity of the original aircraft.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An eddy current generator based on magnetron plasma includes an insulating shell. An annular groove is formed on one end face of the insulating shell, and a cathode is embedded within the annular groove. A through-hole is formed at the center of the annular groove, and an anode is placed within the through-hole. A cylindrical magnet is placed inside the insulating shell, and the magnet has a hollow structure extending through both ends along its axial direction. The hollow structure overlaps axially with the through-hole of the insulating shell.

[0006] The upper surface of the cathode, the end face of the insulating shell inlaid with the cathode, and the upper surface of the anode are flush with each other, and the power line passes through the insulator from the other end of the insulating shell and connects to the anode and cathode.

[0007] In the above technical solution, the cylindrical magnet is positioned between the cathode and the anode in a radially relative position.

[0008] A design method for an eddy current generator based on magnetron-controlled plasma includes the following steps:

[0009] S1: The eddy current generator uses a closed-type design, encapsulating the anode, cylindrical magnet, and cathode within an insulator.

[0010] S2: Based on S1, a cylindrical coaxial arrangement is placed between the anode and the annular cathode;

[0011] S3: The anode and cathode are disposed on the surface of the insulating shell, with the upper surfaces of the anode and cathode flush with the surface of the insulating shell. The cylindrical magnet is disposed inside the insulating shell, with an axial gap between the top of the cylindrical magnet and the upper surfaces of the cathode and anode.

[0012] In the above technical solution, the Lorentz force experienced by the plasma discharge channel during uniform rotation is approximately equal to the air resistance:

[0013]

[0014] in: It is 1 / 2 of the inner diameter of the cathode. The drag coefficient for the rotation of the plasma discharge channel. The diameter of the generated plasma discharge channel, The density of the gas medium, The rotation frequency of the plasma discharge channel. The current in the plasma discharge channel, This represents the magnetic field strength of the cylindrical magnet at the plasma discharge channel.

[0015] In the above technical solution, the axial distance between the top of the cylindrical magnet and the upper surfaces of the cathode and anode is obtained by solving the following optimization function:

[0016]

[0017] in: It is half the axial length of the cylindrical magnet. The inner diameter of the cylindrical magnet. The outer diameter of the cylindrical magnet. To solve for the function parameters of L, , The goal of the optimization function is to find the optimal magnetic field position of the discharge plasma in the hollow cylindrical permanent magnet.

[0018] In the above technical solutions, The maximum value corresponds to the axial distance L between the top of the cylindrical magnet and the upper surfaces of the cathode and anode.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0020] Traditional open-type plasma vortex generators produce additional shock waves at the opening. This device is closed-type, and after being embedded in the original aircraft surface, it does not change the original aircraft surface shape and structure, and will not cause additional shock waves.

[0021] In traditional plasma eddy current generators, both the anode and cathode are located inside the hollow cylinder. In this device, the anode is inside the cylinder, and the cathode is outside the magnet. When both the anode and cathode are inside the hollow cylinder, a larger magnet is required. This device reduces the size of the required magnet and the overall size of the device.

[0022] This device generates rotating discharge plasma on the surface of the electrode ring, thereby disturbing the original flow field and achieving active flow control. This disturbance method of the original flow field is different from the traditional single energy deposition or single vortex jet disturbance method by using energy deposition and rotating plasma flow mixing to change the flow characteristics of the original flow field. Attached Figure Description

[0023] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0024] Figure 1 This is a schematic diagram of the structure of the device of the present invention;

[0025] Figure 2 It is the calculation process for the optimal position of the ring magnet;

[0026] Wherein: 1 is the insulating shell, 2 is the cathode, 3 is the anode, 4 is the cylindrical permanent magnet, 5 is the wire, and L is the distance from the anode protruding from the upper surface of the permanent magnet. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] like Figure 1 As shown, this embodiment includes an insulating shell 1. A closed-loop annular groove is provided on the upper surface of the insulating shell 1. A cathode 2 is disposed within the groove, and the cathode 2 is an integral structure forming a closed-loop ring. A recessed hole is provided at the center of the annular groove, axially penetrating the entire insulating shell 1. An anode 3 is disposed within the recessed hole. A permanent magnet 4 is disposed inside the insulating shell 1. The permanent magnet 4 has a cylindrical structure, axially extending through both ends. The permanent magnet 4 is coaxially arranged with the anode 3 within the insulating shell 1, and the through-hole area of ​​the cylindrical permanent magnet 4 corresponds to the position of the recessed hole. External wires 5 pass through the insulating shell 1 and are connected to the cathode 2 and anode 3 respectively.

[0030] The upper surface of the insulating shell 1 is flush with the upper surfaces of the anode 3 and the cathode 2, and all other parts of the anode 3 and the cathode 2 are embedded inside the insulating shell 1. The permanent magnet 4 is disposed inside the insulating shell 1, and there is a gap between the upper surface of the permanent magnet 4 and the upper surface of the insulating shell 1. At the same time, in the radial direction, the permanent magnet 4 is disposed between the anode 3 and the cathode 2.

[0031] The diameter of the anode is 0.2mm~2mm, the inner diameter of the annular cathode is 6mm~70mm, and the thickness of the anode and cathode is 0.2mm~2mm.

[0032] When using this embodiment, the entire eddy current generator device is embedded and fixed inside the aircraft, and the top surface of the high-temperature resistant insulating substrate matches the outer surface of the aircraft.

[0033] When calculating the position of the hollow cylindrical permanent magnet 4, it is necessary to consider various parameters of the plasma discharge channel generated by the electrodes, specifically:

[0034] First, after applying a DC / pulsed / AC high voltage between the anode and cathode, the gas between the two electrodes ionizes to generate discharge plasma. This discharge plasma experiences a Lorentz force within the spatial magnetic field generated by the hollow cylindrical magnet, resulting in rotational motion. The plasma's movement within the gas is subject to gas drag, with the drag increasing at higher speeds. Ultimately, when the Lorentz force on the plasma discharge channel balances the aerodynamic drag, the plasma discharge channel maintains stable rotational motion. At this point, the following formula exists:

[0035] in: It is 1 / 2 of the inner diameter of the cathode. The drag coefficient for the rotation of the plasma discharge channel. The diameter of the generated plasma discharge channel, The density of the gas medium, The rotation frequency of the plasma discharge channel. The current in the plasma discharge channel, This represents the magnetic field strength of the cylindrical magnet at the plasma discharge channel.

[0036] Secondly, based on parameters such as the location, frequency requirements, and size limitations of the aircraft's eddy current generation obtained from CFD calculations or wind tunnel tests, and taking into account the discharge capacity of existing discharge power supplies, the required magnetic field is estimated. The approximate range is determined, and then the required inner diameter of the permanent magnet is calculated based on the theoretical formula for the magnetic field distribution of a cylindrical permanent magnet. , outer diameter and half the height of the cylindrical magnet .

[0037] To ensure the discharge plasma is positioned at the optimal magnetic field location of the hollow cylindrical permanent magnet, the following parameter optimization function is given. hour, The maximum value corresponds to the optimal distance L between the anode and cathode protruding from the upper surface of the permanent magnet.

[0038]

[0039] Finally, after the device design is completed, the discharge current of the plasma is adjusted by controlling the DC / pulse / AC high-voltage discharge power supply to change the rotation frequency of the plasma discharge channel, thereby adapting to different application conditions.

[0040] Example 1

[0041] Assuming CFD calculations show that a disturbance around 36Hz will have a strong control effect on the flow field, and the size of the eddy current generator needs to be less than 25mm, and the existing high-voltage discharge power supply can generate plasma discharge currents of approximately 10mA~30mA, then with I=20mA, f=36Hz, R=11mm, and gas medium density of 1.175kg / m³, 3 d=2mm, Cd=1.1μm 3 The required magnetic field size can be calculated to be approximately 0.1T. Based on the magnetic field distribution characteristics of a hollow cylindrical permanent magnet, a hollow cylindrical magnet with an inner diameter of 3mm, an outer diameter of 20mm, and a height of 20mm can be selected. The curve showing the change with z is obtained. Figure 2 The optimal parameter L=4mm can be calculated. Therefore, the diameter of the single active eddy current generator of the cylindrical structure is 25mm and the thickness is 26mm. By adjusting the high-voltage discharge power supply parameters, the rotation frequency range of the plasma discharge channel can be obtained as 26Hz~44Hz.

[0042] According to application needs, the vortex generator of the present invention can be arranged into an array structure to realize active flow control of the aircraft.

[0043] 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. An eddy current generator based on magnetron-controlled plasma, characterized in that... The device includes an insulating shell, an annular groove on one end face of which a cathode is embedded. A through hole is located at the center of the annular groove, and an anode is located within the through hole. A cylindrical magnet is located within the insulating shell, and the magnet has a hollow structure extending through both ends along its axial direction. The hollow structure overlaps axially with the through hole of the insulating shell. The upper surface of the cathode, the end face of the insulating shell with the embedded cathode, and the upper surface of the anode are flush with each other. A power line passes through the insulating shell from the other end and connects to the anode and cathode.

2. The eddy current generator based on magnetron-controlled plasma according to claim 1, characterized in that... In a radially relative position, the cylindrical magnet is positioned between the cathode and the anode.

3. A design method for an eddy current generator based on magnetized plasma, characterized in that... Includes the following steps: S1: The eddy current generator adopts a closed-type design, encapsulating the anode, cylindrical magnet, and cathode within an insulator. S2: Based on S1, a cylindrical magnet is coaxially positioned between the anode and the annular cathode; S3: The anode and cathode are disposed on the surface of the insulating shell, with the upper surfaces of the anode and cathode flush with the surface of the insulating shell. The cylindrical magnet is disposed inside the insulating shell, with an axial gap between the top of the cylindrical magnet and the upper surfaces of the cathode and anode.

4. The design method of an eddy current generator based on magnetron plasma according to claim 3, characterized in that: The Lorentz force experienced by the plasma discharge channel during uniform rotation is approximately equal to the air resistance. ,in: It is 1 / 2 of the inner diameter of the cathode. The drag coefficient for the rotation of the plasma discharge channel. The diameter of the generated plasma discharge channel, The density of the gas medium, The rotation frequency of the plasma discharge channel. The current in the plasma discharge channel, This represents the magnetic field strength of the cylindrical magnet at the plasma discharge channel.

5. The design method of an eddy current generator based on magnetron-controlled plasma according to claim 3, characterized in that: The axial distance between the top of the cylindrical magnet and the upper surfaces of the cathode and anode is obtained by solving the following optimization function: ,in: It is half the axial length of the cylindrical magnet. The inner diameter of the cylindrical magnet. The outer diameter of the cylindrical magnet. To solve for the function parameters of L , This is the optimization function.

6. The design method of an eddy current generator based on magnetron-controlled plasma according to claim 3, characterized in that: The maximum value corresponds to the axial distance L between the top of the cylindrical magnet and the upper surfaces of the cathode and anode.

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