Dual disk channel liquid metal magnetohydrodynamic generator

Abstract

The application provides a double-disc channel liquid metal MHD generator, which is cylindrical and consists of coaxial disc liquid metal generator channels and a cylindrical permanent magnet, wherein the disc liquid metal generator channels are embedded in the cylindrical permanent magnet; the disc liquid metal generator channels have two coaxial disc generator channels, which are respectively located in two annular working air gaps of the cylindrical permanent magnet, and each disc generator channel is provided with a pair of plate-shaped electrodes arranged in the radial direction; the cylindrical permanent magnet is a cylinder with a central through hole, has two annular working air gaps coaxial with the central through hole, and generates same-direction axial magnetic fields in the two working air gaps; in the two disc generator channels, the liquid metal flows in the radial direction and in opposite directions, the magnetic field directions are axial and same, the generated circumferential induced currents are in opposite directions; and the electrodes of the two disc generator channels are connected in series.

Description

Technical Field

[0001] This invention relates to a liquid metal magnetohydrodynamic generator, and more particularly to a conductive liquid metal magnetohydrodynamic generator with two disc-type power generation channels. Background Technology

[0002] Liquid metal magnetohydrodynamic (MHD) generators are widely used in variable displacement automotive engines, distributed power supply in residential areas, space thermoelectric conversion, and direct ocean energy generation. Based on the different modes of electromagnetic field interaction, MHD generators are classified into conductive and inductive types. In conductive MHD generators, the liquid metal moves in a transverse magnetic field, and the generated electrical energy is directly output through electrodes. This type has a simple structure, wide application range, and is currently a research hotspot. The induced electromotive force (EMF), or open-circuit voltage, of a conductive MHD generator is proportional to the liquid metal flow velocity, the magnetic flux density of the applied magnetic field, and the characteristic distance. Currently, the commonly used linear rectangular cross-section power generation channel has an applied magnetic field characteristic distance equal to the electrode spacing, typically on the order of 10⁻⁶. -2 -10 -1 The external magnetic field of a liquid metal magnetohydrodynamic generator is typically generated by a permanent magnet, with a magnetic flux density of approximately 1 T within the generator channel and a liquid metal flow velocity on the order of 10 m. 1 m / s. Therefore, the magnitude of the induced electromotive force in current conductive liquid metal magnetohydrodynamic generators is generally on the order of 10. -1- 10 0 V, the output voltage is typically on the order of 10. -1 The current voltage (V) cannot meet the requirements for subsequent high-efficiency power conversion, severely affecting the practicality of its output electrical energy. How to improve the output voltage of the conductive liquid metal magnetohydrodynamic generator and achieve its efficient power conversion and output is a pressing technical problem that needs to be solved. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention proposes a conductive liquid metal magnetohydrodynamic generator with two disc-shaped power generation channels. The perimeter of the disc-shaped power generation channel is approximately equal to the characteristic distance of the applied magnetic field, and the electrodes of the two power generation channels are connected in series, thereby improving the induced electromotive force and output voltage of the liquid metal magnetohydrodynamic generator.

[0004] The technical solution of this invention is: a dual-disc channel liquid metal magnetohydrodynamic generator, wherein the liquid metal magnetohydrodynamic generator is cylindrical and consists of coaxial disc-shaped liquid metal power generation channels and cylindrical permanent magnets. The disc-shaped liquid metal power generation channels are embedded in the cylindrical permanent magnets. The disc-shaped liquid metal power generation channels are flow channels through which liquid metal flows in and out axially. There are two coaxial disc-shaped power generation channels located in the two annular working air gaps of the cylindrical permanent magnets. A pair of flat plates are arranged radially in each disc-shaped power generation channel. The surface of the electrodes in contact with the liquid metal in the disc-shaped power generation channel is a conductive surface, and the remaining non-conductive surfaces are electrically insulated. The central angle between the conductive surfaces of the two electrodes is... Let θ1 be the angle between the non-conductive surfaces of the two electrodes corresponding to the conductive surfaces, and let θ2 be the central angle occupied by the two electrodes and the insulating plate between them. Let θ1 + θ2 = 360° and θ1 / θ2 ≥ 3. The cylindrical permanent magnet is a cylinder with a central through hole and two annular working air gaps coaxial with the central through hole. An axial magnetic field is generated in the two annular working air gaps, and the magnetic field direction is the same. The disk-type liquid metal current generation channel is coaxially located in the central through hole and the two working air gaps. In the two disk-type power generation channels, the liquid metal flows radially in opposite directions. The magnetic field direction is axial and the direction is the same. The induced current generated is circumferential and the direction is opposite. The electrodes of the two disk-type power generation channels are connected in series.

[0005] The disc-shaped liquid metal power generation channel consists of a central inlet, an upper disc-shaped power generation channel, an annular flow channel, a lower disc-shaped power generation channel, a central outlet, four electrodes, and two insulating plates. The two insulating plates are located between the two electrodes of the upper and lower disc-shaped power generation channels, and at their circumferential relative positions within the annular flow channel. The central inlet, upper disc-shaped power generation channel, annular flow channel, lower disc-shaped power generation channel, and central outlet are coaxial and connected in series, forming a connected flow space in which the liquid metal flows. The liquid metal flows axially into the central inlet, radially from the inside to the outside in the upper disc-shaped power generation channel, and circumferentially into the annular flow channel at its end, where it flows axially. The lower plate-type power generation channel flows radially from the outside to the inside and flows axially out from the central outlet; the central angle of the flow space of the upper plate-type power generation channel and the lower plate-type power generation channel is θ1, and the central angle of the flow space of the annular channel is slightly larger than θ1; the central inlet and the central outlet coaxially pass through the central through hole of the cylindrical permanent magnet, the upper plate-type power generation channel coaxially passes through the upper working air gap of the cylindrical permanent magnet, the lower plate-type power generation channel coaxially passes through the lower working air gap of the cylindrical permanent magnet, and the annular channel is coaxially located outside the two working air gaps and the middle magnetic ring of the cylindrical permanent magnet; two radial through holes are set at 180° intervals in the circumferential direction of the annular channel, one of which is axially located between the two insulating plates.

[0006] The cylindrical permanent magnet is a cylinder with a central through hole, consisting of an upper yoke, a lower yoke, an annular yoke, an upper magnetic ring, an upper working air gap, a middle magnetic ring, a lower working air gap, a lower magnetic ring, a central through hole, and two support rods. The upper yoke, lower yoke, upper magnetic ring, upper working air gap, middle magnetic ring, lower working air gap, and lower magnetic ring are all annular, with a circular air gap of equal diameter forming the central through hole. The upper yoke, annular yoke, and lower yoke form the cylindrical yoke frame. The upper magnetic ring, upper working air gap, middle magnetic ring, lower working air gap, lower magnetic ring, central through hole, and two support rods are symmetrically arranged within the cylindrical interior space of the cylindrical yoke frame. The upper and lower magnetic rings are coaxially arranged between the upper and lower yokes. The upper magnetic ring is coaxially and tightly attached to the inner surface of the upper yoke, the lower magnetic ring is coaxially and tightly attached to the inner surface of the lower yoke, and the middle magnetic ring is coaxially arranged between the upper and lower working air gaps and fixed to the annular yoke by two support rods. The magnetization direction of the upper, middle, and lower magnetic rings is axial and the same. A closed magnetic circuit is formed in any RZ plane by the sequence: upper magnetic ring → upper working air gap → middle magnetic ring → lower working air gap → lower magnetic ring → lower yoke → annular yoke → upper yoke → upper magnetic ring. This generates an axially symmetric magnetic field in the same direction within the upper and lower working air gaps. A hole is made at an appropriate position on the annular yoke for the cable connecting the electrodes to pass through.

[0007] The two support rods of the cylindrical permanent magnet are made of non-magnetic material, are 180° apart in the circumferential direction and pass through two through holes in the annular flow channel of the disk-type liquid metal current generation channel in the radial direction. The radial length of each support rod is greater than the sum of the axial heights of the upper working air gap and the lower working air gap.

[0008] The disc-shaped liquid metal current-generating channel is made of non-conductive and non-magnetic material, or is made of non-magnetic material with its inner surface electrically insulated.

[0009] The insulating board is made of a non-magnetic and non-conductive material.

[0010] Using the above technical solution, for a disc-type power generation channel with an average diameter of D, the average circumference L = πD. If the circumferential thickness of the electrodes and insulating plate is not considered, the distance between the conductive surfaces of the two electrodes is approximately equal to L. Under the same spatial dimensions, the maximum electrode spacing in a linear power generation channel is D. L / D ≈ 3.14. Under the same conditions of magnetic flux density, liquid metal flow velocity, and load factor, the induced electromotive force and output voltage generated by the disc-type power generation channel are significantly increased, reaching 3.14 times that of the linear channel. Connecting the electrodes of two disc-type power generation channels in series doubles the induced electromotive force and output voltage, meeting the requirements for efficient subsequent energy conversion and output. Furthermore, the cylindrical permanent magnet generates an axially symmetric magnetic field within the annular working air gap, eliminating the magnetic field end gradient and energy loss generated in the linear power generation channel, further improving the performance of the liquid metal magnetohydrodynamic generator. Attached Figure Description

[0011] Figure 1 This is a three-dimensional diagram of a specific embodiment of the present invention, wherein the origin of the coordinate system is at the geometric center of the embodiment: 1. Disk-shaped liquid metal current generation channel; 2. Cylindrical permanent magnet.

[0012] Figure 2 This is a specific embodiment of the present invention: a disc-type liquid metal current generation channel; 1-1 center inlet, 1-3 annular channel, 1-5 center outlet, 1-6-1 electrode plate A, 1-6-2 electrode plate B, 1-6-3 electrode plate C, 1-6-4 electrode plate D, 1-7-1 insulating plate A, 1-7-2 insulating plate B.

[0013] Figure 3 This is a three-dimensional cross-sectional view of a cylindrical permanent magnet according to a specific embodiment of the present invention, wherein the annular yoke is cut in quarter section; 2-1 upper yoke, 2-2 upper magnetic ring, 2-3 middle magnetic ring, 2-4 lower magnetic ring, 2-5 lower yoke, 2-6 annular yoke, 2-7-1 support rod A, 2-7-2 support rod B, 2-8-1 upper working air gap, 2-8-2 lower working air gap, 2-9 central through hole;

[0014] Figure 4 This is a specific embodiment of the present invention. Figure 1 Three-dimensional cross-sectional view of the YZ plane: 1-1 Central inlet, 1-2 Upper plate-type power generation channel, 1-3 Annular channel, 1-4 Lower plate-type power generation channel, 1-5 Central outlet, 1-6-1 Electrode plate A, 1-6-2 Electrode plate B, 1-7-1 Insulating plate A, 1-7-2 Insulating plate B, 2-1 Upper yoke, 2-2 Upper magnetic ring, 2-3 Middle magnetic ring, 2-4 Lower magnetic ring, 2-5 Lower yoke, 2-6 Annular yoke, 2-7-1 Support rod A, 2-7-2 Support rod B;

[0015] Figure 5 This is a specific embodiment of the present invention. Figure 1 Three-dimensional cross-sectional view of the XY plane: 1-3 Annular channel, 1-6-2 Electrode plate B, 1-6-4 Electrode plate D, 2-3 Middle magnetic ring, 2-5 Lower yoke, 2-6 Annular yoke, 2-7-1 Support rod A, 2-7-2 Support rod B. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] Figures 1-5 In a specific embodiment of the present invention, the origin of the Cartesian coordinate system is located at the geometric center of the dual-disc channel liquid metal magnetohydrodynamic generator, and the Z-axis is the axial direction. Figure 4 The arrows in the diagram indicate the flow direction of the liquid metal in the disc-type liquid metal power generation channel; N and S are the magnetic pole directions of the cylindrical permanent magnet ring.

[0018] like Figure 1 As shown, the dual-disc channel liquid metal magnetohydrodynamic generator is cylindrical and consists of a coaxial disc-type liquid metal power generation channel 1 and a cylindrical permanent magnet 2. The disc-type liquid metal power generation channel 1 is embedded in the cylindrical permanent magnet 2.

[0019] The disc-type liquid metal power generation channel 1 is a flow channel for liquid metal to flow in and out axially. It consists of a central inlet 1-1, an upper disc-type power generation channel 1-2, an annular channel 1-3, a lower disc-type power generation channel 1-4, a central outlet 1-5, electrodes A1-6-1, B1-6-2, C1-6-3, D1-6-4, an insulating plate A1-7-1, and an insulating plate B1-7-2. The central inlet 1-1, upper plate-type power generation channel 1-2, annular flow channel 1-3, lower plate-type power generation channel 1-4, and central outlet 1-5 are coaxial and connected in series to form a connected flow space in which liquid metal flows. Electrodes A1-6-1 and C1-6-3 are arranged radially in the upper plate-type power generation channel 1-2, and electrodes B1-6-2 and D1-6-4 are arranged radially in the lower plate-type power generation channel 1-4. Insulating plate A1-7-1 is located between electrodes A1-6-1 and C1-6-3 in the upper plate-type power generation channel 1-2 and at a corresponding position circumferentially in the lower annular flow channel 1-3. Insulating plate B1-7-2 is located between electrodes B1-6-2 and D1-6-4 in the lower plate-type power generation channel 1-4 and at a corresponding position circumferentially in the upper annular flow channel 1-3. The annular flow channel 1-3 has two radial through holes spaced 180° apart in the circumferential direction. One of the through holes is axially located between insulating plates A1-7-1 and B1-7-2. Electrodes A1-6-1, B1-6-2, C1-6-3, and D1-6-4 are flat plates. The surfaces of electrodes A1-6-1 and C1-6-3 that contact the liquid metal in the upper disk-type power generation channel 1-2 are conductive surfaces; the remaining non-conductive surfaces are electrically insulated. The central angle θ1 between the conductive surfaces of electrodes A1-6-1 and C1-6-3, and the central angle θ2 occupied by electrodes A1-6-1, insulating plate A1-7-1, and electrode C1-6-3 satisfy θ1 + θ2. = 360° and θ1 / θ2≥3; the surfaces of electrodes B1-6-2 and D1-6-4 that contact the liquid metal in the lower plate-type power generation channel 1-4 are conductive surfaces, and the remaining non-conductive surfaces are electrically insulated. The central angle between the conductive surfaces of electrodes B1-6-2 and D1-6-4 is also θ1, and the central angle occupied by electrodes B1-6-2, insulating plate B1-7-2, and electrodes D1-6-4 is also θ2. θ1 and θ2 also satisfy θ1+θ2=360° and θ1 / θ2≥3. The central angle of the flow space in the upper plate-type power generation channel 1-2 and the lower plate-type power generation channel 1-4 is also θ1, and the central angle of the flow space in the annular flow channel 1-3 is slightly larger than θ1.

[0020] The cylindrical permanent magnet 2 is a cylinder with a central through hole 2-9, consisting of an upper yoke 2-1, an upper magnetic ring 2-2, a middle magnetic ring 2-3, a lower magnetic ring 2-4, a lower yoke 2-5, an annular yoke 2-6, support rods A 2-7-1 and B 2-7-2, an upper working air gap 2-8-1, a lower working air gap 2-8-2, and a central through hole 2-9. The upper yoke 2-1, annular yoke 2-6, and lower yoke 2-5 form the cylindrical yoke frame. The upper magnetic ring 2-2, upper working air gap 2-8-1, middle magnetic ring 2-3, lower working air gap 2-8-2, lower magnetic ring 2-4, central through hole 2-9, and support rods A 2-7-1 and B 2-7-2 are also present. 2-7-2 are symmetrically arranged within the cylindrical interior space of the cylindrical yoke frame; the upper yoke 2-1, upper magnetic ring 2-2, upper working air gap 2-8-1, middle magnetic ring 2-3, lower working air gap 2-8-2, lower magnetic ring 2-4, and lower yoke 2-5 are annular, with a central through hole 2-9 formed by a circular air gap of equal diameter in the middle. The upper magnetic ring 2-2, upper working air gap 2-8-1, middle magnetic ring 2-3, lower working air gap 2-8-2, and lower magnetic ring 2-4 are coaxially arranged between the upper yoke 2-1 and lower yoke 2-5. The upper magnetic ring 2-2 is coaxially and tightly attached to the inner surface of the upper yoke 2-1, the lower magnetic ring 2-4 is coaxially and tightly attached to the inner surface of the lower yoke 2-5, and the middle magnetic ring 2-3 is coaxially arranged between the upper working air gap 2-8-1 and lower working air gap 2-8-2, and is supported by support rod A 2-7-1 and support rod B. 2-7-2 is fixed on the annular yoke 2-6; the magnetization direction of the upper magnetic ring 2-2, the middle magnetic ring 2-3 and the lower magnetic ring 2-4 is in the -Z direction. On any RZ plane, a closed magnetic circuit is formed by upper magnetic ring 2-2 → upper working air gap 2-8-1 → middle magnetic ring 2-3 → lower working air gap 2-8-2 → lower magnetic ring 2-4 → lower yoke 2-5 → annular yoke 2-6 → upper yoke 2-1 → upper magnetic ring 2-2. An axial magnetic field with axisymmetry is generated in the upper working air gap 2-8-1 and the lower working air gap 2-8-2 and the magnetic field direction is in the -Z direction.

[0021] Support rod A 2-7-1 and support rod B 2-7-2 are made of non-magnetic material and are 180° apart in the circumferential direction. The radial length of support rod A 2-7-1 and support rod B 2-7-2 is greater than the sum of the axial heights of the upper working air gap 2-8-1 and the lower working air gap 2-8-2.

[0022] like Figure 4 and Figure 5As shown, the central inlet 1-1 and the central outlet 1-5 coaxially pass through the central through hole 2-9 of the cylindrical permanent magnet 2. The upper plate-type power generation channel 1-2 coaxially passes through the upper working air gap 2-8-1 of the cylindrical permanent magnet 2. The lower plate-type power generation channel 1-4 coaxially passes through the lower working air gap 2-8-2 of the cylindrical permanent magnet 2. The annular flow channel 1-3 is coaxially located outside the upper working air gap 2-8-1, the middle magnetic ring 2-3, and the lower working air gap 2-8-2 of the cylindrical permanent magnet 2. The support rod A 2-7-1 radially passes through the through hole of the annular flow channel 1-3 located between the insulating plate A1-7-1 and the insulating plate B1-7-2. The support rod B 2-7-2 passes through another through hole of the annular flow channel 1-3. Electrodes A1-6-1 and B1-6-2 are connected, and electrodes C1-6-3 and D1-6-4 are connected to cables, which can be led out through the perforations on the annular yoke 2-6. Liquid metal flows axially into the central inlet 1-1, radially from the inside to the outside in the upper plate-type power generation channel 1-2, axially downwards in the annular flow channel 1-3, and radially from the outside to the inside in the lower plate-type power generation channel 1-4, finally flowing axially out from the central outlet 1-5. The central angle of the flow spaces in the upper plate-type power generation channel 1-2, the lower plate-type power generation channel 1-4, and the annular flow channel 1-3 is less than 360°, and the central angle of the flow spaces in the upper plate-type power generation channel 1-2 and the lower plate-type power generation channel 1-4 is θ1. In the upper plate-type power generation channel 1-2, the liquid metal flows away from the center, the magnetic field is in the -Z direction, and looking down from +Z, the induced current is counterclockwise. Electrode A1-6-1 is the negative electrode and electrode C1-6-3 is the positive electrode. In the lower plate-type power generation channel 1-4, the liquid metal flows towards the center, the magnetic field is in the -Z direction, and looking down from +Z, the induced current is clockwise. Electrode B1-6-2 is the positive electrode and electrode D1-6-4 is the negative electrode.

[0023] Insulating plates A1-7-1 and B1-7-2 are made of non-magnetic and non-conductive materials; the central inlet 1-1, upper plate-type power generation channel 1-2, annular channel 1-3, lower plate-type power generation channel 1-4, and central outlet 1-5 are made of non-conductive and non-magnetic materials; the upper yoke 2-1, lower yoke 2-5, and annular yoke 2-6 are made of magnetic materials, such as Q235; the upper magnetic ring 2-2, middle magnetic ring 2-3, and lower magnetic ring 2-4 are made of permanent magnet materials, such as neodymium iron boron N50.

[0024] The average diameter D of the upper plate-type power generation channel 1-2 and the lower plate-type power generation channel 1-4 is 0.1m, the average magnetic flux density B is 1.0T, the liquid metal flow velocity u is 20m / s, and the central angle θ1 between the conductive surfaces of electrodes A1-6-1 and C1-6-3 and between the conductive surfaces of electrodes B1-6-2 and D1-6-4 is 330°. Therefore, the sum of the induced electromotive forces generated by the upper plate-type power generation channel 1-2 and the lower plate-type power generation channel 1-4 is U0d = 5.76V × 2 = 11.51V. With a load factor K = 0.8, the output voltage Ud = 9.21V. Under the same spatial dimensions, the maximum electrode spacing of a single linear power generation channel is D = 0.1m, generating an induced voltage of 2.0V. The induced electromotive force of two linear power generation channels connected in series is U0l = 4.0V, with a load factor K = 0.8, and the output voltage is Ul = 3.2V. Ud / Ul = 2.88, meaning that under the same conditions, the induced electromotive force and output voltage generated by the disc-type power generation channel are 2.88 times that of the linear type, which greatly improves the induced electromotive force and output voltage, and greatly facilitates the efficient conversion and output of subsequent electrical energy.

[0025] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-disc channel liquid metal magnetohydrodynamic generator, characterized in that: The liquid metal magnetohydrodynamic generator is cylindrical, consisting of a coaxial disc-shaped liquid metal power generation channel and a cylindrical permanent magnet. The disc-shaped liquid metal power generation channel is embedded in the cylindrical permanent magnet. The disc-shaped liquid metal power generation channel is a flow channel for axial inflow and axial outflow of liquid metal, with two coaxial disc-shaped power generation channels located within the two annular working air gaps of the cylindrical permanent magnet. Each disc-shaped power generation channel has a pair of flat plates arranged radially. The surface of the electrode in contact with the liquid metal in the disc-shaped power generation channel is the conductive surface, while the remaining non-conductive surfaces are electrically insulated. The conductive surfaces of the two electrodes are separated by... The central angle θ1 and the central angle θ2 occupied by the two electrodes and the insulating plate between them satisfy θ1+θ2=360° and θ1 / θ2≥3; the cylindrical permanent magnet is a cylinder with a central through hole and two annular working air gaps coaxial with the central through hole. An axial magnetic field is generated in the two working air gaps and the magnetic field direction is the same. The disk-type liquid metal power generation channel passes coaxially through the central through hole and the two working air gaps; in the two disk-type power generation channels, the liquid metal flows radially and the flow direction is opposite. The magnetic field direction is axial and the direction is the same. The induced current generated is circumferential and the direction is opposite; the electrodes of the two disk-type power generation channels are connected in series. The disc-type liquid metal power generation channel consists of a central inlet, an upper disc-type power generation channel, an annular channel, a lower disc-type power generation channel, a central outlet, and electrodes A, B, C, and D. It consists of insulating plate A and insulating plate B; the central inlet, upper plate-type power generation channel, annular flow channel, lower plate-type power generation channel and central outlet are coaxial and connected in series to form a connected flow space in which liquid metal flows. The central angle of the flow space of the upper plate-type power generation channel and the lower plate-type power generation channel is θ1, and the central angle of the flow space of the annular flow channel is slightly greater than θ1; electrodes A and C are arranged radially in the upper plate-type power generation channel, and electrodes B and D are arranged radially in the lower plate-type power generation channel; insulating plate A is located between electrodes A and C in the upper plate-type power generation channel and at a corresponding position in the circumferential direction of the lower annular flow channel, and insulating plate B is located between electrodes B and D in the lower plate-type power generation channel and at a corresponding position in the circumferential direction of the upper annular flow channel; there are two radial through holes spaced 180° apart in the circumferential direction of the annular flow channel, one of which is axially located between insulating plate A and insulating plate B.

2. The dual-disc channel liquid metal magnetohydrodynamic generator according to claim 1, characterized in that: The cylindrical permanent magnet is a cylinder with a central through hole, consisting of an upper yoke, an upper magnetic ring, a middle magnetic ring, a lower magnetic ring, a lower yoke, an annular yoke, support rods A and B, an upper working air gap, a lower working air gap, and a central through hole. The upper yoke, annular yoke, and lower yoke form the cylindrical yoke frame. The upper magnetic ring, upper working air gap, middle magnetic ring, lower working air gap, lower magnetic ring, central through hole, and support rods A and B are symmetrically arranged inside the cylindrical yoke frame. The upper yoke, upper magnetic ring, upper working air gap, middle magnetic ring, lower working air gap, lower magnetic ring, and lower yoke are all annular, with a central through hole formed by a circular air gap of equal diameter in the middle. The upper magnetic ring, upper working air gap, and middle magnetic ring... The lower working air gap and the lower magnetic ring are coaxially arranged between the upper and lower yokes. The upper magnetic ring is coaxially and tightly arranged on the inner surface of the upper yoke, and the lower magnetic ring is coaxially and tightly arranged on the inner surface of the lower yoke. The middle magnetic ring is coaxially arranged between the upper and lower working air gaps and is fixed to the annular yoke by support rods A and B. The magnetization direction of the upper, middle, and lower magnetic rings is axial and the magnetization direction is the same. In any RZ plane, a closed magnetic circuit is formed by upper magnetic ring → upper working air gap → middle magnetic ring → lower working air gap → lower magnetic ring → lower yoke → annular yoke → upper yoke → upper magnetic ring. An axial magnetic field with axisymmetry is generated in the upper and lower working air gaps and the magnetic field direction is the same.

3. The dual-disc channel liquid metal magnetohydrodynamic generator according to claim 2, characterized in that: Support rods A and B are made of non-magnetic material and are 180° apart in the circumferential direction. Their radial length is greater than the sum of the axial heights of the upper and lower working air gaps, and they pass radially through two through holes in the annular flow channel.

4. The dual-disc channel liquid metal magnetohydrodynamic generator according to any one of claim 1 or claim 2, characterized in that: Insulating plate A and insulating plate B are made of non-magnetic and non-conductive materials; the central inlet, upper plate-type power generation channel, annular channel, lower plate-type power generation channel and central outlet are made of non-magnetic and non-conductive materials, or non-magnetic materials with their inner surfaces electrically insulated; the upper yoke, lower yoke and annular yoke are made of magnetic materials; the upper magnetic ring, middle magnetic ring and lower magnetic ring are made of permanent magnet materials.

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