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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 307 records · Page 17
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NASA NTRS1977

Solar wind nitrogen - Mechanisms for isotopic evolution

Isotope systematics of nitrogen implanted in the lunar regolith indicate that the N-15/N-14 ratio at the source of the nitrogen has increased substantially with time. This source is most plausibly identified as the solar wind reservoir. However, rigorous testing of possible mechanisms for isotopic evolution of the solar convective zone shows that they all fail, by large factors, to explain the observed effect. Evolutionary processes on the lunar surface may be similarly eliminated, leaving the lunar nitrogen isotope anomaly currently unexplained.

Kerridge, J. F.↗
NASA NTRS1978

Carbon, nitrogen and sulfur in Apollo 15, 16 and 17 rocks

Carbon, nitrogen and sulfur contents, as well as carbon isotopic compositions, were determined for seven lunar rocks from the Apollo 15, 16 and 17 missions. Sequential combustion at three temperatures was used to resolve terrestrial contamination from indigenous lunar volatiles. Nitrogen abundances averaged 0.4 micrograms/gram in the samples. The results of the sequential combustion analysis suggested that all the samples contained variable amounts of terrestrial carbon contamination prior to examination. Indigenous lunar carbon abundances ranging from 2.5 to 6 micrograms/gram were found. Thus the moon appears to be substantially depleted in nitrogen and carbon relative to the earth and C and H meteorites.

Des Marais, D. J.↗
NASA NTRS1979

Carbon and nitrogen abundances in red giant stars in the globular cluster 47 Tucanae

The effects of changes in temperature, gravity, overall metal abundance, and carbon and nitrogen abundances have been investigated for model stellar spectra and colors representing globular-cluster giants of moderate metal deficiency. The results are presented in the form of spectral atlases and theoretical color-color diagrams. Using these results, approximate abundances of carbon and nitrogen have been derived for some red giant stars in 47 Tuc, from intermediate- and low-dispersion spectra and from intermediate- and narrow-band photometry. In all the normal giants studied, nitrogen is overabundant by up to about a factor of 5 (the precise value depends on the adopted carbon abundance), with different enhancements for different giants. The observational material is not sufficient to distinguish between a normal carbon abundance and a slight carbon depletion for the giant-branch stars, but carbon appears to be somewhat depleted in stars on the asymptotic giant branch. A most probable value of M/H = -0.8 for the overall cluster metal abundance is suggested from analysis of Stromgren photometry of red horizontal-branch stars.

Dickens, R. J.↗
NASA NTRS1979

Oxides of nitrogen and the clouds of Venus

Nitric oxide may be produced in the atmosphere of Venus by lightning storms in the clouds. The paper suggests that the odd nitrogen thus formed may play an important part in the chemistry of the clouds. Specifically, production rates for NO2 in the limiting case of high NO concentrations are estimated. If the NO density is high, it is suggested that NO2 may catalyse the production of sulfuric acid aerosol from sulfur dioxide and water vapor, and may also form nitrogen-sulfur compounds such as nitrosyl sulfuric acid, NOHSO4. The large partricles seen by the Pioneer Venus sounder probe may contain considerable quantities of NOHSO4. If this is the case, odd nitrogen must be present in the atmosphere in at least a parts-per-million mixing ratio.

Watson, A. J.↗
NASA NTRS1980

Mechanisms of nitrogen heterocycle influence on turbine fuel stability

Lewis bases were extracted from a Utah COED syncrude via ligand exchange. Addition of this extract to Jet A at levels as low as 5 ppm N produced deterioration of stability in both JFTOT and accelerated storage tests (7 days at 394 K with 13:1air to fuel ratio). Comparable effects on Jet A stability were obtained by addition of pyridine and quinoline, while pyrrole and indole were less detrimental at the same concentration level. The weight of deposit produced accelerated storage tests was found to be proportional to the concentration of added nitrogen compound. Over the narrow temperature range accessible with the experimental method, Arrhenius plots obtained by assuming specific rate to be proportional to the weight of material deposited in seven days exhibit greater slopes in the presence of those nitrogen compounds producing the greater deposition rates. It is shown that despite variation in appearance the elemental composition and spectral characteristics of the deposits are unaffected by addition of the nitrogen compounds. The linearity of the Arrhenius plots and of a plot of Arrhenius slope versus intercept for all the compounds suggests a constancy of mechanism over the range of temperature and heterocycles studied.

Daniel, S. R.↗
NASA NTRS1981

Effect of fuel nitrogen and hydrogen content on emissions in hydrocarbon combustion

The results of an investigation of the effect of operating conditions and fuel properties on emission for the two-stage combustion of fuels with significant organic nitrogen content are presented. The way in which the emissions of nitrogen oxides and carbon monoxide are affected by the decreased hydrogen content and the increased organic nitrogen content of coal-derived fuels is discussed. Limited measurements of smoke from the rich-lean combustion of simulated syncrude fuels indicate relatively high smoke emissions in spite of the very lean second-stage burning. This fact, together with the high observed carbon monoxide emissions, suggests that trade-offs will be necessary between the conditions that minimize NOx and those that control CO and smoke emissions.

Bittker, D. A.↗
NASA NTRS1981

The Limb Infrared Monitor of the Stratosphere /LIMS/ experiment - Temperature and nitrogen dioxide results

The Limb Infrared Monitor of the Stratosphere (LIMS) is a satellite-borne radiometer which scans across the earth's limb, measuring infrared radiation emitted by specific atmospheric gases in a number of broad channels. Instrumentation includes a folded telescope, which focuses the radiation from the limb onto an array of six mercury-cadmium-telluride detectors. A scan mirror within the telescope sweeps the fields of view across the horizon, with each up or down scan lasting 12 seconds. The measurements are inverted to yield distributions of temperature and nitrogen dioxide. The temperature is determined from two channels covering the intervals 595-739 per cm and 645-673 per cm of the 15 micron bands of CO2, with maximum signal to noise ratio of 500-1000. Nitrogen dioxide is determined from measurements in a channel from 1580-1613 per cm, with an S/N of approximately 100. Results show that the LIMS temperature and nitrogen dioxide data are characterized by high precision.

Gille, J. C.↗
NASA NTRS1982

Effect of some nitrogen compounds thermal stability of jet A

The effect of known concentrations of some nitrogen containing compounds on the thermal stability of a conventional fuel, namely, Jet A was investigated. The concentration range from 0.01 to 0.1 wt% nitrogen was examined. Solutions were made containing, individually, pyrrole, indole, quinoline, pyridine, and 4 ethylpyridine at 0.01, 0.03, 0.06, and 0.1 wt% nitrogen concentrations in Jet A. The measurements were all made by using a standard ASTM test for evaluating fuel thermal oxidation behavior, namely, ASTM D3241, 'thermal oxidation stability of turbine fuels (JFTOT procedure).' Measurements were made at two temperature settings, and 'breakpoint temperatures' were determined. The results show that the pyrrole and indole solutions have breakpoint temperatures substantially lower than those of the Jet A used.

Antoine, A. C.↗
NASA NTRS1982

Preprototype nitrogen supply subsystem development

The design and development of a test stand for the Nitrogen Generation Module (NGM) and a series of tests which verified its operation and performance capability are described. Over 900 hours of parametric testing were achieved. The results from this testing were then used to design an advanced NGM and a self contained, preprototype Nitrogen Supply Subsystem. The NGM consists of three major components: nitrogen generation module, pressure controller and hydrazine storage tank and ancillary components. The most important improvement is the elimination of all sealing surfaces, achieved with a total welded or brazed construction. Additionally, performance was improved by increasing hydrogen separating capability by 20% with no increase in overall packaging size.

Heppner, D. B.↗
NASA NTRS1982

Stratospheric nitrogen dioxide in the vicinity of Soufriere, St. Vincent

In April 1979, measurements of nitrogen dioxide in the upper atmosphere were made near Soufriere Volcano by twilight optical-absorption techniques. The derived value of 5 x 10 to the 15th molecules per square centimeter column implies an enhancement of 25 percent over earlier abundances measured in the same latitudinal regions. This enhancement may represent the normal stratospheric variability of nitrogen dioxide in the equatorial region, but in any case may be considered an upper limit to the volcano's effect on the total nitrogen dioxide abundance.

Romick, G. J.↗
NASA NTRS1984

Nitrogen Supply Uses Hydrazine

Liquid hydrazine dissociated and residual gas removed to produce almost pure nitrogen. Nitrogen-generation module catalytically dissociates liquid hydrazine then dissociates and separates product gases to yield almost pure nitrogen.

Heppner, D. B.↗
NASA NTRS1984

Nitrogen threshold experiment

In order to obtain data on Earth geologic processes associated with wind erosion, Mar's and Venus' atmospheres were simulated. Experiments were designed to observe the effects of pressure, gravity, and density on sand movement. An experiment designed to test the operator variance was a comparative test between nitrogen and carbon dioxide. Pressure and therefore density was increased until threshold was noted. Threshold was determined at precisely the same densities of the two gases. If viscosity were a contributing factor in grain saltation the effect would be noted at low pressures. The experiment showed no such variance between carbon dioxide and nitrogen runs for low pressure (density). The largest difference in viscosity between carbon dioxide and nitrogen occurs at low pressures (densities).

Treat, C. L.↗
NASA NTRS1984

The global distribution of thermospheric odd nitrogen for solstice conditions during solar cycle minimum

A two-dimensional model of odd nitrogen in the thermosphere and upper mesosphere is described. The global distributions of nitric oxide and atomic nitrogen are calculated for the solstice period for quiet and moderate magnetic activity during the solar minimum period. The effect of thermospheric transport by winds is investigated along with the importance of particle-induced ionization in the auroral zones. The results are compared with rocket and satellite measurements, and the sensitivity of the model to eddy diffusion and neutral winds is investigated. Downward fluxes of NO into the mesosphere are given, and their importance for stratospheric ozone is discussed. The results show that the summer-to-winter pole meridional circulation transports both NO and N(S-4) across the solar terminator into the polar night region where there is a downward vertical transport toward the mesosphere. The model shows that odd nitrogen densities at high winter latitudes are entirely controlled by particle precipitation and transport processes.

Gerard, J.-C.↗
NASA NTRS1984

The case for a Martian origin of the shergottites - Nitrogen and noble gases in EETA 79001

Nitrogen and noble gases have been measured in samples of a glass inclusion and its surrounding basaltic matrix in an Antarctic shergottite meteorite (EETA 79001). The nitrogen component was found trapped in the glass, but not the matrix, having a value of delta 15-N = +190 per mil. Ratios between abundances of Ar-40 and N-14, N-15 and N-14 in the glass are consistent with the dilution of a Martian atmospheric component. The trapped noble gases in the glass are similar to elemental and isotopic compositions measured in Mars atmosphere by the Viking lander, and are in general agreement with previous measurements. It is suggested that a sample of Martian atmosphere has been caught in the EETA 79001 glass, and that other shergottite, nakhilite, and chassignite meteorites with similar features probably also originated on Mars. A table is presented which lists the abundances of nitrogen and the noble gases found in the non-glassy matrix and in the EETA 79001 glass.

Becker, R. H.↗
NASA NTRS1984

Powder containing 2H-type silicon carbide produced by reacting silicon dioxide and carbon powder in nitrogen atmosphere in the presence of aluminum

The production of powder which contains silicon carbide consisting of 40% of 2H-type silicon carbide, beta type silicon carbide and less than 3% of nitrogen is discussed. The reaction temperature to produce the powder containing 40% of 2H-type silicon carbide is set at above 1550 degrees C in an atmosphere of aluminum or aluminum compounds and nitrogen gas or an antioxidation atmosphere containing nitrogen gas. The mixture ratio of silicon dioxide and carbon powder is 0.55 - 1:2.0 and the contents of aluminum or aluminum compounds within silicon dioxide is less than 3% in weight.

Kuramoto, N.↗
NASA NTRS1984

Flow of nitrogen-pressurized Halon 1301 in fire extinguishing systems

Halon 1301 which is a halocarbon fire extinguishing agent (CBrF3) used by the U.S. Army for vehicle fire suppression is discussed. Halon 1301 is discharged under nitrogen pressure, and the Halon-nitrogen mixture is a two phase, two component mixture that obeys compressible fluid laws and exhibits choking effects. A computer model was developed to analyze the discharge of Halon and nitrogen from a storage bottle through pipes and nozzles. The model agrees well with data from Halon 1301 discharge tests. The discharge time depends mainly on nozzle area and pipe volume, for given initial conditions. Graphs were developed for estimating discharge times. A nozzle employing multiple concentric converging/diverging nozzles was developed which gave hemispherical coverage.

Elliott, D. G.↗
NASA NTRS1984

Lightning - Estimates of the rates of energy dissipation and nitrogen fixation

The nitrogen needed by plants can normally not be directly obtained from the nitrogen present in molecular form in the atmosphere. The reason for this situation is related to the great energy required to break the N-N bond. Only a few organisms, such as algae and certain bacteria, can 'fix' nitrogen. An abiological process for breaking the N-N bond is provided by lightning. The present investigation is concerned with this possibility. It is found that lightning produces approximately 2.6 x 10 to the 9th kg N per year. There are, however, uncertainties, which are mainly related to the energy of a lightning flash.

Borucki, W. J.↗
NASA NTRS1987

Agreement between experimental and theoretical effects of nitrogen gas flowrate on liquid jet atomization

Two-phase flows were investigated by using high velocity nitrogen gas streams to atomize small-diameter liquid jets. Tests were conducted primarily in the acceleration-wave regime for liquid jet atomization, where it was found that the loss of droplets due to vaporization had a marked effect on drop size measurements. In addition, four identically designed two-fluid atomizers were fabricated and tested for similarity of spray profiles. A scattered-light scanner was used to measure a characteristic drop diameter, which was correlated with nitrogen gas flowrate. The exponent of 1.33 for nitrogen gas flowrate is identical to that predicted by atomization theory for liquid jet breakup in the acceleration-wave regime. This is higher than the value of 1.2 which was previously obtained at a sampling distance of 4.4 cm downstream of the atomizer. The difference is attributed to the fact that drop-size measurements obtained at a 2.2 cm sampling distance are less effected by vaporization and dispersion of small droplets and therefore should give better agreement with atomization theory. Profiles of characteristic drop diameters were also obtained by making at least five line-of-sight measurements across the spray at several horizontal positions above and below the center line of the spray.

Ingebo, Robert D.↗