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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Hot-wire anemometry for turbulence measurements in helium-air mixtures

The use of extended hot-wire anemometry involving an interfering probe is shown to permit measurements of variable density turbulence such as arises in the mixing of helium and air. The methods of calibration and data reduction leading to time series in one or more velocity components, in the mass fraction of helium, and in the mixture density are described. Typical results in various flows to which the technique has been applied are discussed.

Libby, P. A.↗
NASA NTRS1981

Reduced viscosity interpreted for fluid/gas mixtures

Analysis predicts decrease in fluid viscosity by comparing pressure profile of fluid/gas mixture with that of power-law fluid. Fluid is taken to be viscous, non-Newtonian, and incompressible; the gas to be ideal; the flow to be inertia-free, isothermal, and one dimensional. Analysis assists in design of flow systems for petroleum, coal, polymers, and other materials.

Lewis, D. H.↗
NASA NTRS1981

Thermodynamic and transport properties of air/water mixtures

Subroutine WETAIR calculates properties at nearly 1,500 K and 4,500 atmospheres. Necessary inputs are assigned values of combinations of density, pressure, temperature, and entropy. Interpolation of property tables obtains dry air and water (steam) properties, and simple mixing laws calculate properties of air/water mixture. WETAIR is used to test gas turbine engines and components operating in relatively humid air. Program is written in SFTRAN and FORTRAN.

Fessler, T. E.↗
NASA NTRS1980

Response of selected plant and insect species to simulated SRM exhaust mixtures and to exhaust components from SRM fuels

The possible biologic effects of exhaust products from solid rocket motor (SRM) burns associated with the space shuttle are examined. The major components of the exhaust that might have an adverse effect on vegetation, HCl and Al2O3 are studied. Dose response curves for native and cultivated plants and selected insects exposed to simulated exhaust and component chemicals from SRM exhaust are presented. A system for dispensing and monitoring component chemicals of SRM exhaust (HCl and Al2O3) and a system for exposing test plants to simulated SRM exhaust (controlled fuel burns) are described. The effects of HCl, Al2O3, and mixtures of the two on the honeybee, the corn earworm, and the common lacewing and the effects of simulated exhaust on the honeybee are discussed.

Heck, W. W.↗
NASA NTRS1980

Lasing characteristics of gas mixtures involving UFG: Application to nuclear pumping of lasers

Intense blue-green fluorescence from a structured band centered at lambda approximately 484 nm was observed from Ar, CF3I and NF3 gas mixtures excited by an electron beam. This emission was tentatively assigned to the E yields A transition of the iodine monofluoride (IF) molecule. The fluorescence efficiency of the IF(E yields A) band and the IF (E) state radiative lifetime were estimated to be approximately 6% and 15 ns, respectively. The emission band structure, the short IF(E) radiative lifetime and the Franck-Condon shift between the E and A states suggest that IF is an attractive candidate for a blue-green laser.

Verdeyen, J. T.↗
NASA NTRS1980

Response of selected plant and insect species to simulated solid rocket exhaust mixtures and to exhaust components from solid rocket fuels

The effects of solid rocket fuel (SRF) exhaust on selected plant and and insect species in the Merritt Island, Florida area was investigated in order to determine if the exhaust clouds generated by shuttle launches would adversely affect the native, plants of the Merritt Island Wildlife Refuge, the citrus production, or the beekeeping industry of the island. Conditions were simulated in greenhouse exposure chambers and field chambers constructed to model the ideal continuous stirred tank reactor. A plant exposure system was developed for dispensing and monitoring the two major chemicals in SRF exhaust, HCl and Al203, and for dispensing and monitoring SRF exhaust (controlled fuel burns). Plants native to Merritt Island, Florida were grown and used as test species. Dose-response relationships were determined for short term exposure of selected plant species to HCl, Al203, and mixtures of the two to SRF exhaust.

Heck, W. W.↗
NASA NTRS1980

Ignition of lean fuel-air mixtures in a premixing-prevaporizing duct at temperatures up to 1000 K

Conditions were determined in a premixing prevaporizing fuel preparation duct at which ignition occurred. An air blast type fuel injector with nineteen fuel injection points was used to provide a uniform spatial fuel air mixture. The range of inlet conditions where ignition occurred were: inlet air temperatures of 600 to 1000 K air pressures of 180 to 660 kPa, equivalence ratios (fuel air ratio divided by stoichiometric fuel air ratio) from 0.12 to 1.05, and velocities from 3.5 to 30 m/s. The duct was insulated and the diameter was 12 cm. Mixing lengths were varied from 16.5 to 47.6 and residence times ranged from 4.6 to 107 ms. The fuel was no. 2 diesel. Results show a strong effect of equivalence ratio, pressure and temperature on the conditions where ignition occurred. The data did not fit the most commonly used model of auto-ignition. A correlation of the conditions where ignition would occur which apply to this test apparatus over the conditions tested is (p/V) phi to the 1.3 power = 0.62 e to the 2804/T power where p is the pressure in kPa, V is the velocity in m/e, phi is the equivalence ratio, and T is the temperature in K. The data scatter was considerable, varying by a maximum value of 5 at a given temperature and equivalence ratio. There was wide spread in the autoignition data contained in the references.

Tacina, R. R.↗
NASA NTRS1981

Material response from Mach 0.3 burner rig combustion of a coal-oil mixture

Wedge shaped specimens were exposed to the combustion gases of a Mach 0.3 burner rig fueled with a mixture of 40 weight percent micron size coal particles dispersed in No. 2 fuel oil. Exposure temperature was about 900 C and the test duration was about 44 one hour cycles. The alloys tested were the nickel base superalloys, IN-100, U-700 and IN-792, and the cobalt base superalloy, Mar-M509. The deposits on the specimens were analyzed and the extent of corrosion/erosion was measured. The chemical compositions of the deposits were compared with the predictions from an equilibrium thermodynamic analysis. The experimental results were in very good agreement with the predictions.

Santoro, G. J.↗
NASA NTRS1981

Collisional radiative recombination in high-pressure noble gas mixtures

Rate coefficients are calculated for neutral-assisted collisional radiative recombination in dense, weakly ionized rare-gas mixtures using the quasiequilibrium model developed by Bates. It is shown that the recombination rate can be significantly altered by the presence of a buffer gas. In particular, the presence of helium can enhance the collisional radiative recombination rate coefficient of heavy rare gases by a factor of 5.

Whitten, B. L.↗
NASA NTRS1981

Transport properties for a mixture of the ablation products C, C2, and C3

The ablation of carbon-phenolic heat shields upon entry into the atmosphere of one of the outer planets leads to the injection of large amounts of C, C2, and C3 into the shock layer. These species must be included in the calculation of transport properties in the shock layer. The kinetic theory of gases has been used to obtain accurate results for the transport properties of monatomic carbon. The Hulburt-Hirschelder potential, the most accurate general purpose atom-atom potential for states with an attractive minimum, was used to represent such states and repulsive states were represented by fitting quantum mechanical potential energy curves with the exponential repulsive potential. These results were orientation averaged according to the peripheral force model to obtain transport collision integrals for the C-C2 and C2-C2 interaction. Results for C3 were obtained by ignoring the presence of the central carbon atom. The thermal conductivity, viscosity, and diffusion coefficients for pure C, C2, and C3, and for mixtures of these gases, were then calculated from 1000 K - 25,000 K.

Biolsi, L.↗
NASA NTRS1982

Separating Silicon From Si/NaF Mixtures

New method of extracting silicon from mixture produced when silicon tetrafluoride is reduced by sodium takes advantage of lower melting point of NaF. Method is effective at temperatures up to 400 degrees C below melting point of Si. Results in energy and economic savings: simpler and smaller furnaces, less volatization loss, and high percentage of separation.

Sanjurjo, A.↗
NASA NTRS1982

Solidification of a binary mixture

The time dependent concentration and temperature profiles of a finite layer of a binary mixture are investigated during solidification. The coupled time dependent Stefan problem is solved numerically using an implicit finite differencing algorithm with the method of lines. Specifically, the temporal operator is approximated via an implicit finite difference operator resulting in a coupled set of ordinary differential equations for the spatial distribution of the temperature and concentration for each time. Since the resulting differential equations set form a boundary value problem with matching conditions at an unknown spatial point, the method of invariant imbedding is used for its solution.

Antar, B. N.↗
NASA NTRS1982

Zero-gravity growth of a sodium chloride-lithium fluoride eutectic mixture

Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on Earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convective current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and Earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.

Yue, A. S.↗
NASA NTRS1980

Spectroscopic studies of water and water/regolith mixtures on planetary surfaces at low temperatures

New reflectance spectra of Ganymede, Europe, Callisto, Io, Saturn's rings, and Mars were obtained. The new data is combined with data covering other spectral regions for compositional interpretation. The spectral properties of water and mixtures of water plus other minerals were studied in the laboratory at the low temperatures typical of Mars, the Galilean satellites, and Saturn's rings. High precision reflectance spectra of water ice were studied.

Clark, R. N.↗
NASA NTRS1982

Far infrared spectra of H2 mixtures of H2-CH4 and H2-He

Laboratory measurements of the far infrared absorption of H2 and of mixtures of H2 with CH4 and He are presented, and fits to the pure H2 spectra with a semiempirical line shape are described. Such results are needed in analyzing the thermal emission from the atmospheres of the outer planets.

Birnbaum, G.↗
NASA NTRS1981

Absorption of visible radiation in atmosphere containing mixtures of absorbing and nonabsorbing particles

The presence of a strongly absorbing material, tentatively identified as graphitic carbon, or 'soot', is indicated by measurements of single-scattering albedo of tropospheric aerosols. Although theoretical calculations based on models of the ways in which soot may mix with other aerosol materials yield the single-scattering albedo values of 0.6, accounted for by a minimum 20% soot by volume, in urban regions and 0.8, yielded by 1-5% soot by volume, in rural settings, it is found that these same values can be produced by similar amounts of the iron oxide magnetite. Magnetite is shown to be indistinguishable from soot by optical measurements performed on bulk samples, and calculation of various mixtures of soot indicate the difficulty of determining aerosol composition by optical scattering techniques.

Ackerman, T. P.↗
NASA NTRS1983

Improved 02/H2 Gas Mixture Sensor

Monitor of mixture concentrations uses catalyzed and uncatalyzed temperature probe. Sensor includes Pt-catalyzed temperature probe mounted in line with similar uncatalyzed temperature probe. Use of common temperature probes and standard, flareless, high-pressure tubefittings resulted in design conductive to installation in almost any system. Suitable for use in regenerative fuel cells, life-support systems, and other closed systems.

Moulthrop, L. C.↗