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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

High pressure combustion of liquid fuels

Measurements were made of the burning rates and liquid surface temperatures for a number of alcohol and n-paraffin fuels under natural and forced convection conditions. Porous spheres ranging in size from 0.64-1.9 cm O.D. were emloyed to simulate the fuel droplets. The natural convection cold gas tests considered the combustion in air of methanol, ethanol, propanol-1, n-pentane, n-heptane, and n-decane droplets at pressures up to 78 atmospheres. The pressure levels of the natural convection tests were high enough so that near critical combustion was observed for methanol and ethanol vaporization rates and liquid surface temperature measurements were made of droplets burning in a simulated combustion chamber environment. Ambient oxygen molar concentrations included 13%, 9.5% and pure evaporation. Fuels used in the forced convection atmospheric tests included those listed above for the natural convection tests. The ambient gas temperature ranged from 600 to 1500 K and the Reynolds number varied from 30 to 300. The high pressure forced convection tests employed ethanol and n-heptane as fuels over a pressure range of one to 40 atmospheres. The ambient gas temperature was 1145 K for the two combustion cases and 1255 K for the evaporation case.

Canada, G. S.↗
NASA NTRS1991

The high-pressure melting curve of iron - A technical discussion

The melting curve of iron is reliably determined to 105 GPa using the laser-heated diamond cell, in close agreement with independent measurements using piston-cylinder and large-volume presses or shock-wave experiments. In order to obtain reliable melting data from the internally heated diamond cell, whether by laser or Joule heating, temperature gradients across the sample must be quantitatively measured; otherwise, such 'wire heating' experiments can lead to significant underestimates of the melting temperature and its pressure dependence. The best estimate of the high-pressure melting curve of iron, as derived from the laser-heated diamond cell and Hugoniot temperature measurements, yields melting temperatures of 4800 + or - 200 K and 6700 + or - 400 K at 133 GPa and 243 GPa, respectively.

Williams, Quentin↗
NASA NTRS1984

Feedthrough Seal For High-Pressure Vessel

Combination of ceramic and plastic withstands many depressurizations. Stack of washers surrounds leadthrough electrode. Under pressure washers expand to fill leadthrough hole in high-pressure vessel. Seal thus formed withstands 20 or more pressurization/depressurization cycles. Seal composed of neoprene, polytetrafluoroethylene, nylon and high-purity, high-density commercial alumina ceramic.

Williams, R.↗
NASA NTRS1981

Apparatus for high-pressure and low-temperature experiments

A new type of apparatus for high-pressure experiments at low temperature (1.5 K) is presented. It uses a flat diamond anvil with a spherical indentor. It utilizes a load ring placed under the sample, so that the load (and hence pressure) can be measured in situ at low temperature. The apparatus was successfully used to investigate the high-conductivity state of sulphur. It can be used to investigate other thin film samples.

Golopentia, D. A.↗
NASA NTRS1978

Influence of high pressure hydrogen on cyclic load crack growth in metals

The effect of high pressure hydrogen on the crack growth rate of various nickel-base alloys was studied at ambient temperature. Considerable enhancement of the cyclic flaw growth rate was observed for Inconel 718, wrought and cast, and Waspaloy, a nickel-base alloy similar to Inconel 718. Only slight enhancement of the flaw growth rate for Alloy 903 was observed.

Jewett, R. P.↗
NASA NTRS1992

Prospects for high pressure imaging gas scintillation drift chambers

The current developmental status and future potential of a promising hard X-ray and gamma ray detector are presented: the high pressure xenon gas scintillation imaging drift chamber. A scheme for reading out the scintillation light waveshifting fibers, which allows operation at pressures at least as high as 20 atmospheres, is used. This technique combines excellent spatial resolution (approximately 200 rms allowing 1.5 arcminute mapping resolution), very good energy resolution (within a factor of three of Ge detectors), good time resolution (approximately 100 ns), and extremely high sensitivity because of excellent background rejection capabilities; it also offers possibilities for extrapolation to large area detectors. Results from tests with a prototype chamber are presented. The design of a scientific instrument for a balloon flight planned in 1995 is described. This instrument, the Scintillation Imaging Gas filled Hard X-ray Telescope (SIGHT), is optimized for detecting 30 to 300 keV X-rays. It has an active area of 1140 sq cm, with a stopping power of between 2.0 and 2.7 g/sq cm of xenon at 20 atmospheres. Possible future evolutionary tracks of the technology leading to innovative satellite applications are discussed.

Edberg, T. K.↗
NASA NTRS1972

Lattice model calculation of elastic and thermodynamic properties at high pressure and temperature

The elastic constants and the entire frequency spectrum were calculated up to high pressure for the alkali halides in the NaCl lattice, based on an assumed functional form of the inter-atomic potential. The quasiharmonic approximation is used to calculate the vibrational contribution to the pressure and the elastic constants at arbitrary temperature. By explicitly accounting for the effect of thermal and zero point motion, the adjustable parameters in the potential are determined to a high degree of accuracy from the elastic constants and their pressure derivatives measured at zero pressure. The calculated Gruneisen parameter, the elastic constants and their pressure derivatives are in good agreement with experimental results up to about 600 K. The model predicts that for some alkali halides the Grunesen parameter may decrease monotonically with pressure, while for others it may increase with pressure, after an initial decrease.

Demarest, H. H., Jr.↗
NASA NTRS2010

Metal/Silicate Partitioning at High Pressures and Temperatures

The behavior of siderophile elements during metal-silicate segregation, and their resulting distributions provide insight into core formation processes. Determination of partition coefficients allows the calculation of element distributions that can be compared to established values of element abundances in the silicate (mantle) and metallic (core) portions of the Earth. Moderately siderophile elements, including W, are particularly useful in constraining core formation conditions because they are sensitive to variations in T, P, oxygen fugacity (fO2), and silicate composition. To constrain the effect of pressure on W metal/silicate partitioning, we performed experiments at high pressures and temperatures using a multi anvil press (MAP) at NASA Johnson Space Center and laser-heated diamond anvil cells (LHDAC) at the University of Maryland. Starting materials consisted of natural peridotite mixed with Fe and W metals. Pressure conditions in the MAP experiments ranged from 10 to 16 GPa at 2400 K. Pressures in the LHDAC experiments ranged from 26 to 58 GPa, and peak temperatures ranged up to 5000 K. LHDAC experimental run products were sectioned by focused ion beam (FIB) at NASA JSC. Run products were analyzed by electron microprobe using wavelength dispersive spectroscopy. Liquid metal/liquid silicate partition coefficients for W were calculated from element abundances determined by microprobe analyses, and corrected to a common fO2 condition of IW-2 assuming +4 valence for W. Within analytical uncertainties, W partitioning shows a flat trend with increasing pressure from 10 to 16 GPa. At higher pressures, W becomes more siderophile, with an increase in partition coefficient of approximately 0.5 log units.

Shofner, G.↗
NASA NTRS1988

The simulation of the alternate turbopump development high pressure oxygen and fuel turbopumps for the space shuttle main engine using the Shaberth computer program

The Space Shuttle Main Engine (SSME) is basically comprised of a combustion chamber and nozzle, high and low pressure oxygen turbopumps and high and low pressure fuel turbopumps. In the current configuration, the high pressure fuel (HPTFP) and high pressure oxygen turbopumps (HPOTP) have experienced a history of ball bearing wear. The wear problem can be attributed to numerous factors including the hydrodynamic axial and radial loads caused by the flow of liquid oxygen and liquid hydrogen through the turbopump impellers and turbine. Also, friction effects between the rolling elements, races, and cage can create thermally induced bearing geometry changes. To alleviate some of the current configuration problems, an alternate turbopump development (ATD) was proposed. However, the ATD HPOTP and HPTFP are constrained to operate interchangeably with the current turbopumps, thus, the operation conditions must be similar. The ATD configuration features a major change in bearings used to support the integrated shaft, impeller, and turbine system. A single ball and single roller will replace the pump-end and turbine and duplex ball bearings. The Shaft-Bearing-Thermal (SHABERTH) computer code was used to model the ATD HPOTP and ATD HPFTP configurations. A two bearing model was used to simulate the HPOTP and HPFTP bearings and shaft geometry. From SHABERTH, a comparison of bearing reaction loads, frictional heat generation rates, and Hertz contact stresses will be attempted with analysis at the 109 percent and 65 percent power levels.

Mcdonald, Gary H.↗
NASA NTRS1968

High pressure helium purifier Patent

Apparatus and method capable of receiving large quantity of high pressure helium, removing impurities, and discharging at received pressure

Hauser, J. A.↗
NASA NTRS1972

Determination of impact sensitivity of materials at high pressures

Compact device is used to determine impact sensitivity of material in static, high pressure, gaseous environment. It can also be instrumented to monitor and record pressure, temperature, and striker impact force. Device is used in conjunction with commercially available liquid oxygen impact tester which provides impact energy.

Davis, L.↗