Contains research objectives and reports on three research projects.U. S. Air Force (Research and Technology Division) under Contract AF33(615)-1083 with the Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Ohi

Brown, G. A.

Hoffman, M. A.

Jackson, W. D.

Kerrebrock, J. L.

McCune, James E.

Pierson, E. S.

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XVIII. ENERGY CONVERSION RESEARCHA. Power Systems with Liquid GeneratorsAcademic and Research StaffProf. W. D. Jackson Prof. E. S. PiersonProf. G. A. Brown R. P. PorterGraduate StudentsE. K. LevyR. J. ThomeRESEARCH OBJECTIVES1. Liquid-Metal Magnetohydrodynamic Power GenerationThis phase of our research is concerned with the development of efficient stagnationpressure generators and cycles for use in liquid-metal MHD power systems. The con-densing ejector, a two-phase jet pump, is being studied as a possible stagnation pres-sure generator.Detailed thermodynamic studies of single-stage and multistage condensing ejectorcycles are being carried out and the determination of system weight and MHD generatorcharacteristics is also being undertaken. The stability of the liquid jet and the mixingprocesses in the condensing ejector are being analyzed. The experimental phase of thecondensing-ejector study includes performance measurements for high-efficiency oper-ation and detailed measurements of mixing-section processes.G. A. Brown2. Magnetohydrodynamic Induction GeneratorThe MHD induction machine utilizes the interaction between a traveling magneticfield (such as that produced by a polyphase winding) and a channeled, flowing fluid thatmay be either a plasma or a liquid metal. Only with a liquid metal is the interactionsufficient for a practical generator.The theory has reached the point where the operation of the generator is well under-stood. Effort will be concentrated during the coming year on considering all of the neces-sary factors in designing a practical induction generator. Chief among these are thebest method of minimizing the effect of finite machine length, and including variablechannel area, or variable fluid velocity, in the analysis. Also, a study of the inductionmachine with a mist flow will be finished.The preliminary study of the experimental induction machine with a low-velocity flowloop has been completed. A new flow loop with increased flow rate and available pres-sure is now under construction. After testing the existing machine on the new flow loop,an experimental program to study end effects will be started, which will include thedesign of a new type of coil system and tests on a rotating machine to simulate the lin-ear finite-length machine.W. D. Jackson, E. S. PiersonThis work is supported by the U. S. Air Force (Research and Technology Division)under Contract AF33(615)-1083 with the Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio.QPR No. 80 153(XVIII. ENERGY CONVERSION RESEARCH)STATUS OF RESEARCH1. Liquid-Metal Magnetohydrodynamic Power Generation -Cycle StudiesThe simple single-stage cycle consists of a boiler, condensing ejector, MHD gen-erator and radiator. This cycle will be designated BCEGR cycle. The over-all perform-ance analysis for the condensing ejector has been used with the BCEGR cycle toestimate cycle efficiency. For the BCEGR cycle the efficiency is determined by twoparameters. One parameter is the ratio of vapor velocity to liquid velocity at the mixing-section inlet. The other parameter is a combination of thermodynamic properties of theworking fluid, operating pressure, and MHD generator efficiency. The results of thisstudy will be presented in the next progress report.G. A. Brown2. Experimental Condensing Ejector Studies(i) The coftdensing ejector test facility has been modified to permit more accuratemeasurement of the steam conditions at the steam orifice. Dampers have been obtainedfor the pressure measurement system to reduce the observed pressure oscillations.Additional performance data have been taken under conditions similar to those reportedin Quarterly Progress Report No. 79 (pages 149-151). Agreement with other dataand theoretical predictions was excellent. The design of a higher contraction ratiomixing section has been started.(ii) A visual-flow mixing section has been designed and its fabrication started. Themixing section has a constant diameter, is made of high-temperature (400*F) transparentplastic and will contain instrumentation for obtaining data on the axial pressure and tem-perature histories of the vapor and liquid streams. Wall static taps will be used for pres-sure measurements. Thermocouple probes will be placed at several axial positions. Ata given position, the probes will be displaced in the streams so as to obtain data on theradial temperature profiles. Visual and photographic observations will be made on thejet stability and break-up, drop formation and migration, and so forth. These measure-ments will be compared with predictions from the available mixing-section analysis. Thistest section will serve the purpose of obtaining preliminary detailed data for use in thedesign of later visual-flow test sections and high-efficiency mixing sections.G. A. Brown3. Liquid-Metal Magnetohydrodynamic GeneratorsThe design of the new test loop is completed, and the required parts are under con-struction or on order. It is expected that the flow loop will be in operation and readyfor tests with the existing coil structure by the end of the next quarter.QPR No. 80 154(XVIII. ENERGY CONVERSION RESEARCH)The design study of practical MHD induction generators is progressing. A betterunderstanding of the difficulties and objectives has been obtained.The initial theory of the MHD induction machine with a mist flow includes the inter-action of single drops with the traveling field and equivalent experiments. A refinedsingle-drop theory will give better correlation with the experiments, and the theory willbe extended to include many drops and their mutual interactions.W. D. Jackson, E. S. PiersonQPR No. 80 155XVIII. ENERGY CONVERSION RESEARCHB. Alkali-Metal Magnetohydrodynamic GeneratorsAcademic and Research StaffProf. J. L. KerrebrockProf. M. A. HoffmanProf. G. C. OatesGraduate StudentsR. Decher M. L. Hougen D. J. VasicekR. Dethlefsen G. W. Zeiders, Jr.RESEARCH OBJECTIVESThe principal objective of this research program is to asses the feasibility ofalkali-metal MHD generators for space power generation. Recent experiments and theo-retical work have added greatly to our understanding of the electrical behavior of con-densing alkali vapors. One of our chief objectives for the coming year is to improvethis understanding. Another is to operate a large nonequilibrium MHD generator, withthe use of a seeded noble gas as working fluid. The data obtained from it will allow amore realistic assessment of generators that utilize condensable fluid.J. L. Kerrebrock, M. A. HoffmanSTATUS OF RESEARCH: Alkali-Metal Vapor MHD GeneratorsDuring the past quarter, the thesis of Albert Solbes was completed. 1 We are, atpresent, planning the next series of experiments to be done on the potassium facility.A major portion of our effort has been directed toward the construction and checkoutof the large nonequilibrium generator. The facility has been operated at design massflow (0. 4 kg/sec of He) and at 1600'K. Additional external cooling is needed, and therequired equipment is being procured. The generator channel has been constructed andis being leak tested, at present. We estimate that the generator will be run for the firsttime in the early part of December, 1965.J. L. KerrebrockReferences1. See J. L. Kerrebrock, M. A. Hoffman, and A. Solbes, "Characteristics of a PureAlkali-Metal Vapor Plasma," Quarterly Progress Report No. 79, Research Labora-tory of Electronics, M. I. T., October 15, 1965, pp. 167-174.This work is supported by the U. S. Air Force (Research and Technology Division)under Contract AF33(615)-1083 with the Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio.QPR No. 80 156XVIII. ENERGY CONVERSION RESEARCHC. Hall Instabilities and Their Effect on Magnetohydrodynamic GeneratorsAcademic and Research StaffProf. J. E. McCuneGraduate StudentsW. H. Evers, Jr.RESEARCH OBJECTIVESOur research objective is to obtain further experimental information (using appara-tus already available) on the nature of the electrical fluctuations that appear in slightlyionized gases flowing in the presence of a DC magnetic field, and their apparent effectupon the DC (time-average) behavior of the system. Such fluctuations have been observedby several researchers; recently, more detailed information has been obtained in ourlaboratory. The observed fluctuations are thought to be associated with one or more ofthe mechanisms for instability which have been identified theoretically for plasmas ina strong Hall field. Our immediate aim is to attempt to prove or disprove this relation-ship by isolating the various mechanisms through appropriate choice of the working gas,its density and temperature, as well as appropriate choice of the electrical parameters.Since the scope of the project is limited to the use of existing apparatus, several compro-mises with geometry, and so forth, must be made; nevertheless, we expect that signifi-cant new information can be obtained.J. E. McCuneThis work is supported by the U. S. Air Force (Research and Technology Division)under Contract AF33(615)-1083 with the Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio.QPR No. 80 157

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