Analysis of a two-fluid EHD power generator including effects of compressibility

A detailed analysis and method of calculation is presented for determining the complete thermodynamic cycle of either a one-fluid or a two-fluid electrohydrodynamic (EHD) power generator. The analysis takes fully into account the compressibility of the media. Parameters are included which express the thermodynamic losses in the various components of the overall system. The severe restriction on output created by the electrical breakdown limit of the medium is clearly shown. The method for computing the net-electrical work output per unit mass of primary fluid and the net overall thermal efficiency of the system is carefully developed. The calculation procedure is illustrated by a completely worked out numerical example. The techniques presented here may be used to determine the performance possibilities and limitations of various one-fluid and two-fluid EHD power generators. (Author)Prepared for: U.S. Department of Energyhttp://archive.org/details/analysisoftwoflu00gawaInteragency Agreement No ER-78-A-03-2122N

Gas properties computational procedure suitable for electronic calculators

A calculating procedure is presented, based on a least squares polynomial approximation, for duplicating existing tabular values of selected thermodynamic and transport properties of various important gases. Most of the data refer to ideal gases; however, for functions of both temperature and pressure , the pressure has been specified such that the polynomial approximations have only temperature as the independent variable. Suggested algorithms for polynomial evaluations up to the sixth degree are presented and optimized for hand-held or desk top calculators. Using the suggested polynomial fits and a suitable calculator, it is possible to duplicate existing table values for the various functions of the selected gases without interpolation of reference to the tables per se. The error of the included fits is generally less than 0.5%. With the lowest order approximation the error can be as high as 1%. (Author)The work reported herein is the outcome of a directed study course (AE 4900) in the Department of Aeronautics.http://archive.org/details/gaspropertiescom00andrNAApproved for public release; distribution is unlimited

EHD Research: Final report for the year 1968-69

The research in electrohydrodynamics is concerned with how charged particles can be generated in the laboratory with a potentially useful range of sizes, of charge, and of number density. It is suggested that refined measurement techniques are needed to check on just what is being injected into the flow. The effects of turbulence on the EHD process and, particularly, on breakdown are being studied. The report discusses in some detail the possible role of turbulence on the mean effective mobility of charged particles. On the experimental side, a laboratory facility was built and then improved by the addition of a larger test section and other equipment. Work is proceeding to further develop and refine the instrumentation. Two types of injectors were operated, namely, molecular and two phase, and the latter shows potential for efficient operation. It was concluded tentatively that turbulence in the carrier fluid increases its breakdown potential, and that turbulent air may be a suitable medium for the EHD energy conversion process. (Author)http://archive.org/details/ehdresearchfinal00biblN

Electrogasdynamic Spectral Anemometer

PatentAn electrogasdynamic spectral anemometer including a particle injector and a particle collector that are inserted into a turbulent fluid stream that is under investigation. The injector includes a hollow cylinder into which near saturated steam from an outside source is introduced. The injector also includes a nozzle, a corona needle and an attractor ring which are oppositely charged and located within the nozzle. As the steam passes through the nozzle it supersaturates and condenses into droplets having a size that is primarily determined by the condition of the incoming steam. The droplets are then charged through the corona developed between the corona needle and the attractor ring. Then the charged droplets are ejected from the nozzle and into the stream to be measured where they follow its rapid fluctuations. These charged particles move towards the collector which may be placed downstream of the injector. When a charged particle passes the collector it becomes neutralized and transmits an electrical signal into collector circuitry where it is analyzed to provide information about the intensity of the turbulence at various frequencies. Different droplet sizes are used for different turbulent frequencies of interest depending on the maximum value of the frequency present in the flow

Field-ionization based electrical space ion thruster using a permeable substrate

PatentA field-ionization based electrical ion thruster utilizes a single propellant that can be used in either a high specificimpulse mode, i.e., ion-thruster mode, or a low-specific-impulse mode, i.e., a cold-gas thruster mode. In one embodiment, the high specific impulse mode (ion thruster mode) utilizes a miniaturized positive-ion field-ionization chamber including a permeable substrate infused with properly oriented carbonnanotubes (CNTs), which is fed propellant from a porous injection plug made from permeable carbon or equivalent material. In one embodiment, field-electron emission from a neutralizer, such as a carbon nanotube array neutralizer, positioned after one or more accelerator grids is used for ion neutralization. In one embodiment, the low specific- impulse ( cold-gas mode) uses a conventional supersonic nozzle-expansion to generate thrust. In one embodiment, both the high specific-impulse mode and the low specificimpulse mode thruster embodiments share the same gas propellant, storage propellant tank, and delivery equipment

Temperature dependence of gas properties in polynomial form

Based on a least-squares polynomial approximation, a procedure is introduced for calculating existing tabular values of thermodynamic and transport properties for common gases. The specific heat at constant pressure is given for 238 gases, the thermal conductivity for 55 gases, the dynamic viscocity for 58 gases, and the second and third virial coefficients for 14 gases. At sufficiently low pressures, ideal gas behavior prevails and temperature may be used as the single independent variable. The algorithm for nested multiplication is presented, optimized for hand-held or desktop electronic calculators. Using the polynomial approximations and a suitable calculator, it is possible to duplicate existing reference source tabular values directly, obviating the need for interpolation or further reference to the tables per se. The accuracy of the calculated values can be within 0.5% of the tabular values. The polynomial coefficients are given in the International System of Units (SI). Methods are presented to calculate the temperature corresponding to a given property value. Extrapolation features of the polynomials are discussedThe work presented herein is the result of an attempt to make our earlier report (NPS-57Zi7407lA) more useful. No explicit sponsorship is identifiable.http://archive.org/details/temperaturedepen00and

Optimally loaded electrohydrodynamic power generator

By requiring that the local electrical field strength in an electrohydrodynamic (EHD) power generator be everywhere uniformly close to the critical limit, an optimum channel shape can be established. This shape is based on the one-dimensional flow of a compressible fluid into which are injected unipolar charged particles of negligible mobility. The maximum electrical work output per unit mass of fluid that can be attained in this way is shown to be greater by a factor of two than that of the best comparable channel of uniform areaPrepared for: Department of Energy, Washington, DC.http://archive.org/details/optimallyloadede00biblInter Agency Agreement No. ER-78-A-03-212

Performance of an EHD power generator with a two-fluid ejector

A detailed analysis and method of calculation is presented for determining the complete thermodynamic cycle of a two-fluid electrohydrodynamic (EHD) power generator. The analysis takes fully into account the compressibility of the media. Parameters are included which express the thermodynamic losses in the various components of the overall system. The severe restriction on output created by the electrical breakdown limit of the medium is clearly shown. The method for computing the net-electrical work output per unit mass of primary fluid and the net overall thermal efficiency of the system is carefully developed. A sample output together with the FORTRAN program are included. (Author)The work reported herein was supported by the U.S. Department of Energy, Washington, D.C.http://archive.org/details/performanceofehd00gawaInteragency Agreement No. ER-78-A-0 3-212

Resume of Oscar Biblarz, 1981

Naval Postgraduate School Faculty ResumeIn January, 1968, he joined the faculty of the Naval Postgraduate School, Monterey, California, teaching in the Aeronautics Department

Performance analysis of a type of electrohydrodynamic power generator

This report develops a detailed analysis of a type of electrohydrodynamic power generator which employs an ejector and a so-called 'fluid flywheel' as essential components. The medium is steam containing electrically charged water droplets. The analysis takes into account the experimentally established facts that the maximum strength of the electrical field that can be sustained at incipient breakdown at the most critical location is proportional to the fluid density at that location. It is shown that as a consequence of this fact, the electrical output can be maxmized by designing the primary jet for an exit Mach number of 0.71. Estimates are made of the pump work required, of mixing losses in the ejector and of friction and secondary flow losses. The mathematical analysis is reduced to a fully non-dimensional form and the key dimensionless parameters that govern performance are clearly identified. A preliminary estimate is made of the numerical values of these parameters and the overall performance of the system is esitmated on this basis. (Author)Prepared for: U.S. Department of Energyhttp://archive.org/details/performanceanaly00gawaInter Agency Agreement No. ER-78-A-03-212