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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 NTRS1964

Some Theoretical Aspect of Cryosorption

When a gas or vapor is allowed to come to equilibrium with a solid surface, the concentration of gas molecules is always found to be greater in the immediate vicinity of the surface than in the free gas phase, regardless of the nature of the gas or of the surface. The process by which this surface excess is formed is termed adsorption. In any solid, the atoms at the surface are subject to unbalanced forces of attraction normal to the surface plane; the balance of forces is partially restored by the adsorption of gas molecules. If the forces responsible for adsorption are of van der Waals type, the process is called physical adsorption. Furthermore, if the solid (and its surface) are maintained at relatively low temperatures (say 50°K or below), the term cryosorption is used.

ADSORPTION↗
NASA NTRS1987

Calculating Theromodynamic And Transport Properties Of Fluids

Computer program incorporates van der Waals equation and correction tables. FLUID program developed to calculate thermodynamic and transport properties of pure fluids in both liquid and gas phases. Properties calculated by use of simple gas model, empirical corrections, and efficient numerical interpolation scheme. Produces results that agree very well with measured values. Much faster than older, more complex programs developed for same purpose.

Proctor, Margaret P.↗
NASA NTRS1990

Properties of the ISM - Gas in the halo

The properties of interstellar gas in the galactic halo are reviewed. Halo gas is found to have a wide range of physical conditions with temperatures ranging from less than 170 K to more than 200,000 K. The gas extending away from the plane of the Milky Way has density scale heights ranging from less than 300 pc for certain species in the neutral medium to approximately 3000 pc for the most highly ionized gas. The complex kinematical characteristics of the gas provides important clues about its origin. The gas phase elemental abundances in the neutral halo gas are closer to solar than is found for the highly depleted gas of the Milky Way disk. The possible origin of gas at large distances away from the galactic plane is discussed.

Savage, Blair D.↗
NASA NTRS1992

Feasibility study of a low-energy gamma ray system for measuring quantity and flow rate of slush hydrogen

As part of a study to demonstrate the suitability of an X-ray or gamma ray probe for monitoring the quality and flow rate of slush hydrogen, mass attenuation coefficients for Cd-109 X- and gamma radiation in five chemical compounds were measured. The Ag-109 K rays were used for water and acetic acid, whereas E3 transition from the first excited state at 87.7 keV in Ag-109 provided the probe radiation for bromobenzene, alpha (exp 2) chloroisodurene, and cetyl bromide. Measurements were made for a single phase (gas, liquid, solid) as well as mixed phases (liquid plus solid) in all cases. It was shown that the mass attenuation coefficient for the selected radiations is independent of the phase of the test fluids or phase ratios in the case of mixed phase fluids. Described here are the procedure and the results for the five fluid systems investigated.

Singh, Jag J.↗
NASA NTRS2004

Multiplex coherent raman spectroscopy detector and method

A multiplex coherent Raman spectrometer (10) and spectroscopy method rapidly detects and identifies individual components of a chemical mixture separated by a separation technique, such as gas chromatography. The spectrometer (10) and method accurately identify a variety of compounds because they produce the entire gas phase vibrational Raman spectrum of the unknown gas. This is accomplished by tilting a Raman cell (20) to produce a high-intensity, backward-stimulated, coherent Raman beam of 683 nm, which drives a degenerate optical parametric oscillator (28) to produce a broadband beam of 1100-1700 nm covering a range of more than 3000 wavenumber. This broadband beam is combined with a narrowband beam of 532 nm having a bandwidth of 0.003 wavenumbers and focused into a heated windowless cell (38) that receives gases separated by a gas chromatograph (40). The Raman radiation scattered from these gases is filtered and sent to a monochromator (50) with multichannel detection.

Chen, Peter↗
NASA NTRS2010

Analysis of Flame Deflector Spray Nozzles in Rocket Engine Test Stands

The development of a unified tightly coupled multi-phase computational framework is described for the analysis and design of cooling spray nozzle configurations on the flame deflector in rocket engine test stands. An Eulerian formulation is used to model the disperse phase and is coupled to the gas-phase equations through momentum and heat transfer as well as phase change. The phase change formulation is modeled according to a modified form of the Hertz-Knudsen equation. Various simple test cases are presented to verify the validity of the numerical framework. The ability of the methodology to accurately predict the temperature load on the flame deflector is demonstrated though application to an actual sub-scale test facility. The CFD simulation was able to reproduce the result of the test-firing, showing that the spray nozzle configuration provided insufficient amount of cooling.

Sachdev, Jai S.↗
NASA NTRS1989

Phase-Modulation Gas-Correlation Spectroscopy

Electro-optic phase-modulation gas-correlation spectroscopy demonstrated in laboratory tests promising candidate technique for remote sensing of gases, temperatures, and wind velocities in atmosphere. In technique radiation emitted by sample atmosphere passed through electro-optic phase modulator, and modulated and unmodulated versions of spectrum alternately passed through reference absorption cell containing gas to be detected. Radiation emerging from reference cell band-pass filtered and detected. Correlation signal is difference in intensity between phase-modulated and unmodulated detected signals.

Rider, David M.↗
NASA NTRS2022

Comment on "Observation of Large and All-Season Ozone Losses Over the Tropics" [AIP Advances 12, 075066 (2022)]

As discussed above, and supported by extensive literature, there is no robust, credible observational evidence for substantial ozone depletion (i.e., an “ozone hole”) in the tropics. It is well known that climatological total ozone in the tropics is much lower than that in the mid-latitudes (e.g., Sahai et al., 2000; Weber et al., 2022). Satellite and ozonesonde measurements indicate a 3%–5% per decade decline of tropical lower stratosphere ozone prior to 2000, far smaller than that reported by L2022. The stronger decline reported by L2022 is caused by inappropriate use of the gap-filled version of the TOST ozone dataset, which is based on sparse tropical ozone sondes before the 1990s. This misuse of data (TOST and total column ozone) shows the importance of collaboratively engaging with groups who obtain the measurements and create climatological datasets before performing such analyses. Furthermore, the study by L2022 has multiple flaws in its discussion of atmospheric chemistry and dynamics, particularly in the proposed, and previously refuted (see Sec. III A), cosmicray- driven electron induced (CRE) mechanism. Evidence for the occurrence of tropical stratospheric clouds, as needed for the tropical CRE mechanism, is lacking, nor do CFC-12 observations show signatures of depletion in the tropical lower stratosphere, which could be associated with dissociative electron attachment-induced loss of CFC-12 on particulate matter (i.e., the CRE mechanism). Finally, it is worth reiterating that the CRE mechanism is also not responsible for polar LS ozone depletion. Polar ozone loss can be well explained by the gas phase and heterogeneous chemistry, based on extensive observations and modeling studies documented in many thousands of scientific papers on the topic [e.g., see WMO (2018) and references therein], which is not acknowledged by L2022. L2022’s research paper is a severely flawed one. There is no tropical ozone hole, and the CRE mechanism does not explain observed changes in stratospheric ozone either in the polar regions or in the tropics.

Quality assurance↗
NASA NTRS1996

Electron Impact Excitation of C60 Adducts: Flourescence From C60OH and C60H Species

An investigation concerning possible visible and UV photon emissions by gas phase C(sub 60) ( and C(sub 70)) samples under electron impact excitation was caried out in the 180-750 nm spectral region. Radiation resembling OH (A (sup 2)pi {leads to}X (sup 2){summation}) emission bands and H Balmer series was observed. Based on our investigations, it is concluded that none of the observed emission was associated with the fullerene molecule itself but with the C(sub 60)OH and C(sub 60)H adducts (which are present in the fullerene samples). We also conclude that in these adducts, simultaneous ionization and excitation take place under electron impact and the excited ionic species (C(sub 60)+OH* and C(sub 60)+H*) decay by radiation which was observed in our experiments. These surprising results reveal an interesting new character of buckyball adducts.

gas phase emissions buckyball buckyball adducts fu↗
NASA NTRS2022

The Turning Point of the Aerosol Era

Over the CMIP6 historical period (1850–2014), aerosols provided the largest negative forcing compared to all other climate forcings via their ability to absorb or scatter solar radiation and alter clouds. Aerosols played an important role in counterbalancing warming by greenhouse gases (GHGs). Here we study aerosol forcing trends in the CMIP6 simulations of the NASA Goddard Institute for Space Studies (GISS) ocean-atmosphere ModelE version 2.1 (GISS-E2.1-G) using a fully coupled atmospheric composition configuration, including interactive gas-phase chemistry, and either an aerosol microphysical (MATRIX) or a mass-based aerosol (OMA) module. Simulations of the CMIP6 historical period are analyzed as well as four Shared Socioeconomic Pathway (SSP) future scenarios for 2015–2100: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. The main conclusion of this study is that aerosol forcing in the GISS model has reached its turning point, switching from globally increasing to a decreasing trend in the first decade of the 21st century. This result is robust, independent of which aerosol module or SSP scenario is used. Non-linear aerosol-cloud interactions dominate as a forcing agent over aerosol-radiation interactions. Aerosols' ability to counterbalance GHG forcing on the global scale is today at a level comparable to that at the beginning of the last century. In the 1980s, the decade of largest global aerosol loads, aerosols balanced up to 80% of GHG forcing. As a consequence, global warming of the last decades, which is primarily driven by greenhouse gases, has been augmented by the effect of decreasing aerosol cooling in our model. By the end of this century, following the SSP scenarios, aerosols will only counterbalance 0%–20% of GHG forcing, depending on model and on scenario.

Aerosol forcing↗
NASA NTRS1975

Conversion of laser energy to gas kinetic energy

Techniques for the gas phase absorption of laser radiation for conversion to gas kinetic energy are discussed. Absorption by inverse Bremsstrahlung, in which laser energy is converted at a gas kinetic rate in a spectrally continuous process, is briefly described, and absorption by molecular vibrational rotation bands is discussed at length. High pressure absorption is proposed as a means of minimizing gas bleaching and dissociation, the major disadvantages of the molecular absorption process. A band model is presented for predicting the molecular absorption spectra in the high pressure absorption region and is applied to the CO molecule. Use of a rare gas seeded with Fe(CO)5 for converting vibrational modes to translation modes is described.

Caledonia, G. E.↗
NASA NTRS1979

Measurement in multiphase reacting flows

A survey is presented of diagnostic techniques and measurements made in multiphase reacting flows. The special problems encountered by the presence of liquid droplets, soot and solid particles in high temperature chemically reacting turbulent environments are outlined. The principal measurement techniques that have been tested in spray flames are spark photography, laser anemometry, thermocouples and suction probes. Spark photography provides measurement of drop size, drop size distribution, drop velocity, and angle of flight. Photographs are analysed automatically by image analysers. Photographic techniques are reliable, inexpensive and proved. Laser anemometers have been developed for simultaneous measurement of velocity and size of individual particles in sprays under conditions of vaporization and combustion. Particle/gas velocity differentials, particle Reynolds numbers, local drag coefficients and direct measurement of vaporization rates can be made by laser anemometry. Gas temperature in sprays is determined by direct in situ measurement of time constants immediately prior to measurement with compensation and signal analysis by micro-processors. Gas concentration is measured by suction probes and gas phase chromatography. Measurements of particle size, particle velocity, gas temperature, and gas concentration made in airblast and pressure atomised liquid spray flames are presented.

Chigier, N. A.↗
NASA NTRS1988

Vaporization of ices containing S2 - Implications for comets

An effort is made to ascertain whether the S2 detected in Comet IRAS-Araki-Alcock 1983d can be stored in ices during warming, and is released during the vaporization of its water ice matrix, in view of data on the UV spectrum of S2 in Ar and Kr matrices and water ice in which the ratio of matrix or molecular ice to S2 is of the order of 500:1. The results obtained support the hypothesis that the S2:H2O ratio in the solid phase may not be a predictor of the gas phase ratio. It is concluded that similar vaporization from a cometary nucleus would not release most of the S2 contained in the ice.

Moore, M. H.↗
NASA NTRS1993

The Hubble Space Telescope quasar absorption line key project. III - First observational results on Milky Way gas

Absorption lines found near zero redshift due to Milky Way disk and halo gas in the spectra of 15 quasars observed with the Faint Object Spectrograph (FOS) of the HST at a resolution of about 230 km/s are reported. Results show that Milky Way absorption lines comprise about 44 percent of all absorption lines seen in the first group of Key Project FOS spectra. Milky Way lines were observed for 3C 273 and H1821 + 643. Limits to the Mg-to-H abundance ratio obtained for very high velocity Mg II absorption detections imply gas-phase Mg abundances for the very high velocity gas ranging from more than 0.059 to more than 0.32 times the solar abundance. In all cases where high-velocity H I emission is seen, corresponding high-velocity metal-line absorption is observed.

Savage, Blair D.↗
NASA NTRS1994

The circumstellar environment of IRAS 05338-0624

Millimeter continuum and spectral line observations with 10 sec, 30 sec, and 60 sec resolution are used to characterize the structure and chemistry of the gas around the young, embedded star, IRAS 05338-0624. On arcminute scales, emission from dense gas tracers outline an isolated condensation centered on the IRAS source position. The condensation is characterized by a size of approximately 60 sec, a density of 2 x 10(exp 5)/cc, and a virial mass of 40 solar mass. Interferometric CS J = 2-1 observations show two peaks, one toward the continuum peak and the other toward a position 14 sec west and 8 sec south. Single-dish maps of SO, CH3OH, and SiO show pronounced wing emission to the west of the IRAS source, which interferometer observations reveal to be a compact region of outflow activity. CS emission at redshifted and blueshifted velocities reveals a bipolar outflow oriented with a position angle of 45 deg, while SiO emission appears to be tracing a fast shock interaction region at the CS red-lobe peak, 14 sec west and 8 sec south of the IRAS source. Finally, H(13)CO(+) emission traces clumps of quiescent gas toward the IRAS source and adjacent to the blue lobe of the outflow. Column densities and molecular fractional abundances are derived to explore the interaction between the surrounding condensation and the young stellar object. We find evidence for gas phase depletions within the overall condensation in several gas tracers (CO, CS, HCN, SO) but not in the region immediately around the young stellar object. Enhanced abundances of SO, CH3OH, and SiO (by factors of 4, greater than 100, greater than 1000, respectively) are observed in the shocked gas; these enhancements may be explained in terms of a nondissociative shock liberating mantle materials that contain some amount of refractory materials, a moderate velocity dissociative shock in which only minor sputtering of Si occurs, or a shock that impacts surrounding material with a range of speeds.

Mcmullin, Joseph P.↗
NASA NTRS1994

The abundance of interstellar oxygen toward Orion: Evidence for recent infall?

We present high S/N (greater than 800) Goddard High-Resolution Spectrograph (GHRS) observations of the weak interstellar O I lambda 1356 absorption in the low-density sight lines toward iota Ori and kappa Ori. By comparing these data with observations toward more reddened stars, we find no evidence of density-dependent depletion from the gas phase for oxygen. The derived total oxygen abundance (gas plus grains) towards iota Ori and kappa Ori is consistent with stellar and nebular determinations in Orion at a level that is one-half the solar value. We speculate that the O/H abundance ratio is lower in Orion compared to the Sun because the local Milky Way has suffered a recent infall of metal-poor material, perhaps from the Magellanic Stream.

Meyer, David M.↗
NASA NTRS1995

Fixture For Sampling Volatile Materials In Containers

Fixture based on T-connector enables mass-spectrometric analysis of volatile contents of cylindrical containers without exposing contents to ambient conditions. Used to sample volatile contents of pressurized containers, contents of such enclosed processing systems as gas-phase reactors, gases in automotive emission systems, and gas in hostile environments.

Melton, Donald↗