US3268746A

US3268746A - Magnetogasdynamic electric generator

Info

Publication number: US3268746A
Application number: US79405A
Authority: US
Inventors: Crown John Conrad; Edward A Pinsley
Original assignee: United Aircraft Corp
Current assignee: RTX Corp
Priority date: 1960-12-29
Filing date: 1960-12-29
Publication date: 1966-08-23
Anticipated expiration: 1983-08-23

Description

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Aug. 23, 1966 J. c. CROWN ET AL 3,268,746

MAGNETOGASDYNAMIC ELECTRIC GENERATOR Filed Dec. 29, 1960 /NVE'NTOES JOHN CONRAD CROWN EDWARD A. P/NSLEV BY @fwd fz/Lw@ ArolP/VEV United States Patent O 3,268,746 MAGNETOGASDYNAMIC ELECTRIC GENERATOR John Conrad Crown, West Hartford, Conn., and Edward A. Pinsley, Cambridge, Mass., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Dec. 29, 1960, Ser. No. 79,405 8 Claims. (Cl. S10- 11) This invention relates to magnetogasdynamic electric generators and more particularly to generators orf this type wherein the working fluid is ionized substantially only in the region of electrical generation.

In magnetogasdynamic electric generato-rs wherein an ionized working fluid is passed through a magnetic field to produce electric current, a problem arises as to a shortcircuiting of the current in regions immediately upstream or downstream of the generating region thereby introducing losses and reducing the efiiciency of the device.

It is, therefore, a primary object of lthis invention to provide a magnetogasdynamic electric generator in which the short-circuit losses 4are minimized or completely avoided.

It is a further obje-ct of this invention to provide a generator of -the type described wherein the fluid is appreciably ionized only while owing through the generating region.

It is a still further object of this invention to provide a generator of the type described in which an essentially non-ionized fluid is introduced to the generating region and is ionized by some seeding material. The degree oi ionization and hence the electrical c-onductivity of the working liuid is substantially reduced by the introduction of a quenching fluid in the vicinity of the end of the generating region.

These and other objects of this invention will become readily apparent from the following detailed description ofthe drawing in which:

FIG. l is a schematic illustration of a typical magnetogasdynamic electric lgenerator of the prior art;

FIG. 2 is a `schematic illustration of an improved generator according to this invention;

FIG. 3 is an enlarged portion of FIG. 2 illustrating the wall injection apparatus; and

FIGS. 4 and 5 are side-sectional views of a typical nozzle dor internal injection in the generator.

Referring to FIG. l a typical prior art magnetogasdynamic electric lgenerator is generally indicated at as having an inlet 12 for flowing a high-temperature ionized working fluid. The fluid flows through a generating region which has suitable means (not shown) for passing a magnetic eld generally -indicated by the numeral 14 through the generator. The magnetic field is crossed or cut by the electrically conducting flow so as to generate an electrical current in a direction shown by the arrows 16.

Suitable electrodes

18 and 20` collect this -generated electrical current and conduct it to a suitable load 22.

In an arrangement such as that shown in FIG. 1, it has been known that short-circuit paths are encountered such as shown by the

dotted lines

24 and 26 at the upstream and downstream ends of the generating region. These short-circuits are minimized or eliminated according to this invention and as illustrated in FIG. 2.

Referring to FIG. 2, a relatively high-temperature fluid of several thousand degrees R but in a non-ionized state is introduced through the inlet 32. The tempe-rature though relatively high (in the order of A3060" K.) is insufficient to ionize the incoming stream which may be heated air under pressure. Acording to this invention a supply tank 34 is provided and may contain a suitable seeding material such as liquid alkali metals or for example a saturated solution of an alkali salt (eg. potassium nitrite). The vseeding material from the supply line 35 lpasses through a pump 36 and a suitable valve 38 which can conduct the seeding material to either an injection nozzle 4t) or a wall injection manifold 42 or -both or a series of nozzles. The temperature of the Working fluid and the characteristics of the seed material are such that ionization of the seed material will occur at a short distance downstream of the points of injection and the injectors are located such that the ionization will reach equilibrium -at the upstream end 44 of the main generating region 46. A suitable magnetic field identified by the numeral 43 is passed through the generating region and electrical current represented by the lines 50 flows across the electrodes 52 land 54. The electrodes 52 and 54 are in turn connected to a suitable load 58.

In order to sharply reduce the electrical conductivity of the ow in the region 60 at the downstream end of the gener-ating region an injector nozzle 62 or a wall injection manifold 64 or a series of nozzles may provide for the introduction of an appropriate quenching fluid to the device. This quenching fluid may be a coolant (such as Water) which will lower the fluid temperature so that the degree ozf ionization and hence the electrical conductivity decreases markedly. For appropriate Mach numbers of working iluid flow and for cycles in which the exhaust fluid is not to be used in an auxiliary power generator (eg. a turbine), an additional advantage may be obtained since this coolant may actually increase the stagnation pressure because of the aerothermopressor effect. A second mechanism for the reduction of electrical conductivity would be to introduce a quenching iiuid which has a high electron collision cross-section. In such a case the electrical conductivity is decreased although the temperature and hence the degree of ionization may be relatively unchanged. The addition of the seeding material and `the coolant may be accomplished by either or both devices shown. As for example as shown in FIG. 3, an annular manifold 70 may be provided defining an inner chamber 72 which feeds a fluid out of injector passages 74 leading to the interior of the main generating duct. Also as shown in FIGS. 4 and 5, an injector head 8i) may be utilized and this head may include a number of relatively small passa-ges 82 which are fed from a chamber 86 to which fluid is conducted by -a main feed passage 8S.

As a result of this invention it is apparent that a very eliicient maignetogasdynamic electric generator has been provided whereby the losses due to end effects or shortcircnits are substantially eliminated.

Although several embodiments of 4this invention have been illustrated and described herein, it will be yapparent that various changes may be made in the construction and arrangement of the various parts without ldeparting from the scope of the novel concept.

What it is desired by Letters Patent is:

l. A magnetogasdynamic electric generator comprising an elongated passage, means for forcing a relatively hightemperature non-ionized fluid through said passage, means defining a genera-ting region in a portion of said passage, said generating region having upstream and downstream ends, means for injecting a second fluid into said passage adjacent said upstream end to ionize the liuid at a point substantially coincident with the upstream end of said region, means for generating a magnetic electrical field passing through said generating region, means adjacent said generating region for collecting electrical current generated by the passage of the ionized working fluid through the generating region and means for injecting a quenching material into the working fiuid at a point just prior to the working fluids exit from said generating region to reduce the conductivity of the working fluid.

2. A generator according to claim 1 wherein said second fluid is a liquid metal.

3. A generator according to claim 1 wherein said second fluid is a liquid alkali metal.

4. A magetogasdynamic electric generator comprising an elongated passage, means for owing a relatively hightemperature non-ionized Working fluid through said passage, means dening a generating region in a portion of said passage, said generating region having upstream and downstream ends, means for injecting a seeding material into said passage adjacent said upstream end to ionize the fluid passing thereby and cause the working fluid to become conductive immediately adjacent said upstream end, means for generating a magnetic -eld passing through said generating region, means adjacent said generating region for collecting electrical current generated by the passage of the ionized working lluid through the generating region and means for quenching the working fluid immediately adjacent the downstream end of said generating region to reduce the conductivity of the Working uid.

i5. A generator according to claim 4 wherein said means for injection and quenching include nozzles in said working fluid.

6. A generator according to claim 4 wherein said means for injection and quenching include nozzles in the wall of said passage.

7. A magnetogasdynamic electric generator comprising an elongated passage, means for flowing a relatively hightemperature non-ionized Huid through said passage, means defining a generating region in a portion of said passage, said Working region having upstream and downstream ends, means for injecting a second fluid into said passage adjacent said upstream end to ionize the uid immediately adjacent said upstream and, means for generating a magnetic field passing through said generating region, means adjacent said generating region for collecting electrical 4- current generated by the passage of the ionized working fluid through the generating region, and means for injecting a quenching fluid immediately adjacent but upstream of said downstream end to decrease the ionization of the fluid stream.

8. In a magnetohydrodynamic generator, apparatus for reducing short circuit end effects adjacent the downstream terminal point of oppositely disposed electrodes located within a duct for conveying a hot, electrically conductive comprising: means for introducing a nonconducting fluid gas through a magnetic field at an angle to said electrodes into said duct at about the downstream terminal point of said electrodes whereby the conductivity of at least a portion of said gas is reduced.

References Cited by the Examiner UNITED STATES PATENTS 1,717,413 6/ 1929 Rudenberg 310-11 X 2,754,442 7/ 1956 Boutry 313-63 FOREIGN PATENTS 1,161,079 3/ 1958 France.

OTHER REFERENCES Publication: Power Design and Equipment Application Section, November 1959, pp. 62 and 64.

Publication: Fundamental Processes of Electrical Discharge in Gases, by Loeb, John Wiley & Sons (1941), pp. 374 to 377, inclusive.

Publication: MHD Power Generation Using Nuclear Fuel, by Avco Everett Research Laboratory, March 1960, pages 6 and 16.

MILTON Q. HIRSHFIELD, Primary Examiner.

D. X. SLINEY, Examiner.

Claims

1. A MAGNETOGASDYNAMIC ELECTRIC GENERATOR COMPRISING AN ELONGATED PASSAGE, MEANS FOR FORCING A RELATIVELY HIGHTEMPERATURE NON-IONIZED FLUID THROUGH SAID PASSAGE, MEANS DEFINING A GENERATING REGION IN A PORTION OF SAID PASSAGE, SAID GENERATING REGION HAVING UPSTREAM AND DOWNSTREAM ENDS, MEANS FOR INJECTING A SECOND FLUID INTO SAID PASSAGE ADJACENT SAID UPSTREAM END TO IONIZE THE FLUID AT A POINT SUBSTANTIALLY COINCIDENT WITH THE UPSTREAM END OF SAID REGION, MEANS FOR GENERATING A MAGNETIC ELECTRICAL FIELD PASSING THROUGH SAID GENERATING REGION, MEANS ADJACENT SAID GENERATING REGION FOR COLLECTING ELECTRICAL CURRENT GENERATED BY THE PASSAGE OF THE IONIZED WORKING FLUID THROUGH THE GENERATING REGION AND MEANS FOR INJECTING A QUENCHING