US3515912A - Magnetohydrodynamic apparatus - Google Patents

Description

MAUNETOHYDRODYNAMIC APPARATUS Filed July 17, 1967 3 Sheets-Sheet z United States Patent O 3,515,912 MAGNETOHYDRODYNAMIC APPARATUS Terence Sidwell Wilkinson, Heaton Works, Newcastleupon-Tyne, England, assignor to C. A. Parsons & Company Limited, Newcastle-upon-Tyne, England, a British company Filed July 17, 1967, Ser. No. 653,937 Claims priority, application Great Britain, `luly 28, 1966, 33,932/66 Int. Cl. H02n 4/ 02 U.S. Cl. 310-11 2 Claims ABSTRACT OF THE DISCLOSURE Magnetohydrodynamic apparatus in Which acceleration of an electrically conductive gas is effected along a plurality of flow paths extending in a generally radial direction from an inlet near the axis of a magnet formed as a hollow cylinder to an outlet at the periphery of the magnet.

This invention relates to magnetohydrodynamic apparatus and is concerned in particular with MHD generators although it can also be applied for pumping electrically conductive fluids.

In such apparatus an electrically conductive fluid is driven through a duct across which is formed a magnetic field, with the field being transverse to the direction of fluid flow.

Hitherto, such apparatus has usually taken the form of straight d-ucts in the form of or incorporating a nozzle through Which an electrically conductive gas is accelerated and the magnetic field is formed by poles of an electromagnet formed on opposite sides of the duct.

The object of the invention is to provide magnetohydrodynamic apparatus in which substantially optimum use is made of magnetizing current in a magnetizing coil while the form of the coil is such as to facilitate winding.

The present invention consists in magnetohydrodynamic apparatus comprising at least One magnet in the form of a hollow cylinder and duct means for conveying an electrically conductive fluid in a generally radial direction with respect to the central axis of the magnet, said duct means comprising wall members defining a plurality of flow paths for said fluid from an inlet near the magnet axis to an outlet at the periphery of the magnet.

The invention also consists in apparatus in accordance with the preceding paragraph in which said duct means comprise two opposed wall lying in planes transverse to the magnet axis and spaced apart by further wall members which extend in a generally radial direction.

The invention also consists in apparatus in accordance with the preceding paragraph in which said further wall members have electrodes thereon.

The invention also consists in apparatu in accordance with either of the preceding two paragraphs in which the two opposed walls each have a plurality of radially spaced electrically conductive paths the paths being electrically insulated from one another.

The invention also consists in apparatus in accordance with the preceding paragraph in which the two opposed wall are defined by a plurality of concentric ring conductors each electrically insulated from one another.

The invention also consists in apparatus in accordance with any of the preceding fi ve paragraphs in which there are two cylindrical magnets disposed coaxially but with their ends spaced from one another said duct means lying in the space between the ends of the magnets.

The invention also consists in a magnetohydrodynamic generator comprising two magnets in the form of cylindrical coils disposed coaxially with respect to one another 'ice but with a space between their adjacent ends, duct means in said space for conveying an electrically conductive fluid in a generally radial direction with respect to the common axis of said magnets, said duct means having two opposed walls each disposed transversely with respect to said magnet axis each said *wall having formed thereon a plurality of concentric conductive paths of Circular form separated from one another by electrical insulation, and further walls, substantially perpendicular to said opposed walls, defining a plurality of generally radial flow paths for said fluid, electrodes located on said further walls inlet means substantially co-axial with said magnets for conveying said electrically conductive fluid into said duct means, and outlet means at the periphery of said magnets for collecting electrically conductive fluid leaving said duct means whereby said fluid can flow in a generally radial outward direction across said conductive paths from the inlet to the outlet.

The invention also consists in a magnetohydrodynamic generator in accordance with the preceding paragraph in which the two opposed walls of the duct mean form a convergent-divergent nozzle for the said fluid.

Referring to the accompanying drawings,

FIG. 1 is a section through a magnetohydrodynamic generator in accordance with one embodiment of the invention, the section being on line BB of FIG. 2 which is a section on line AA of FIG. l;

FIG. 3 is an enlarged View of a flow path between two adjacent radially extending walls; and

FIG. 4 is an end View of FIG. 3 looking in the direction of arrow D.

In carrying the invention into effect in the forms illustrated by 'way of example and referring to FIGS. 1 and 2, a magnetohydrodynamic generator comprises two magnets in the form of cylindrical coils 1 and 2. The magnets are disposed co-axially with respect to one another but their adjacent ends are spaced from one another as shown.

In the space between the ends of the magnets is disposed a duct 3 which is adapted to convey an electrically conductive fluid such a a seeded inert gas, for example helium, or seeded combustion products, in a generally radial direction with respect to the common axis CC of the magnets. The duct has two opposed 'walls 3a, 317 which lie in planes transverse to the axis CC as shown and each 'wall has a plurality of concentric closed electrically conductive paths 4.

The paths 4 are represented diagrammatically on FIG. 2 as a plurality of concentric circles. Each circle may represent a solid ring conductor or a tubular ring conductor, with the individual conductors being radially spaced and electrically insulated from one another. In another embodiment, each circle may represent a plurality of spaced modules of electrically conducting material, for example copper, and the individual modules are electrically connected so as to form in effect a ring conductor, with the surfaces of the modules presented to the electrically conductive fluid being insulated from one another and from the modules of adjacent paths. Typical module shapes are indicated in FIG. 2 at 4a.

The conductive paths may be formed on or incorporated in a supporting Wall structure or the paths themselves may constitute the walls 3a and 3b. The paths may, for example, be formed by a plurality of tubular rings, say of copper, with each ring being internally cooled and the ring assembly forming the wall 3a or 3b as the case may be.

Current collection may be from the inner and outer conducting paths.

The conductive paths have been shown as Circular but they may have other regular shapes such as elliptical or be of non-regular shape depending on the desired electrical potential distribution. The provision of such conductive paths is not essential but they have the advantage that they can be used to establish lines of equi-potential in the generator.

Between walls 3a, 3b are located a plurality of further wall members Sa, Sb, Se, Sd which define with the walls 3a, 3b flow paths for the electrically conductive fluid and which flow paths are generally radial.

The walls 5a-5d are shaped so as to direct the fluid in a direction such that a desired radial distribution of electrical potential is achieved. In a preferred, form the conductive paths 4 form concentric circles and represent lines of equi-potential so that there is no potential gradient across any of the walls Sa-Sd. Electrical insulation problems are therefore minimized and only one electrical load need be connected as opposed to the plurality of electrical loads necessary to obtain maximum output from a conventional MHD generator with an axial duct.

It may not in all cases be possible to achieve concentric circles of equi-potential but in general the aim should be to shape the walls Sa-Sd to produce a fluid flow such that the direction of flow is normal to the direction of flow of electric current in the fluid.

The walls Sa-Sd have electrodes 6 associated therewith, electrodes are located on both sides of each wall so that in effect there are four separate ducts in the form shown. More ducts may be provided if desired by using more 'adially extending walls 5. In some instances only two walls 5 may be necessary in which case only two separate ducts need be formed.

In FIG. 2 the electrodes have been shown on only one of the walls, namely Sb, for the sake of clarity, but FIG. 3 shows electrodes on Opposing faces of two adjacent walls Sa and Sb. For the sake of clarity, the electrodes in the reverse sides of walls Sa and Sb have been omitted. The dash lines 7 show diagrammatically electrical connections between electrodes on opposite faces of the walls Sa and 5b. FIG. 3 also shows the connections of the conductive paths and the inner and outer conductive paths formed by modules 4a. The shape of the electrodes can be seen in FIG. 4.

The individual electrodes may be cooled, for example, by means of a liquid such as water. Such cooling may take the form of internal cooling of each electrode in a known manner as for straight ducts in Conventional magnetohydrodynamic apparatus.

The electrically conductive fluid enters duct 3 from an inlet 8 (see FIG. 1) and flows in a generally radial direction to outlets at the periphery of the magnets 1 and 2. The inlet 8 is connected to a duct 9 through which electrically conductive fluid is introduced into the generator. The duct 9 may constitute a combustion chamber the products of combustion of which, when seeded, act as the electrically conductive fluid.

While two magnets have been used in the form illus- 4 trated, in circumstances when one magnet is sufiicient only as need be provided.

The walls on the form shown Sa, 3b are shaped so as to form a convergent-divergent nozzle for the fluid, with the inlet 8 at the throat of the nozzle but such nozzle is not essential.

The outlets for fluid can be arranged to suit the plant in. which the generator is to be incorporated.

By constructing a magnetohydrodynamic generator as described optimum use is made of the magnetizing current applied to the coils 1 and 2. The cylindrical nature of the coil also facilitates winding.

The magnetic field is preferably produced by superconducting coils but Conventional magnetic coils may also be used. The magnet may also have a solid magnetic core, for example of iron.

Additional fluid guiding walls 10, shown in FIG. 2, may be provided if desired so as to provide better control over the flow direction in the outer regions of the duct.

I claim:

1. A magnetohydrodynamc generator comprising two magnets in the form of cylindrical coils disposed coaxially with respect to one another but with a space between their adjacent ends, duct means in said space for conveying an electrically conductive fluid in a generally radial direction with respect to the common axis of said magnets, said duct means having two opposed walls each disposed transversely with respect to said magnet axis each said wall having formed thereon a plurality of concentric conductive paths of circular form separated from one another by electrical insulation, and further walls, substantially perpendicular to said opposed walls, defining a plurality of generally radial flow paths for said fluid, electrodes located on said further walls, inlet means substantailly co-axial with said magnets for conveying said electrically conductive fluid into said duct means, and outlet means at the periphery of said magnets for collecting electrically conductive fiuid leaving said duct means whereby said fluid can flow in a generally radial outward direction across said conductive paths from the inlet to the outlet.

2. The magnetohydrodynamic generator as claimed in claim 1 in which the two opposed walls of the duct means form a convergent-divergent nozzle for said fluid.

References Cited UNITED STATES PATENTS 2,847,936 8/1958 Richter 103-1 3,360,666 12/1967 Klein a 310-11 3,406,301 10/1968 Rosa 310 -11 DAVID X. SLINEY, Primary Examiner U.S. Cl. X.R. 103-1

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