Search NASA⌕ Search

SEARCH · Search NASA

Results for “GAS TRANSPORT”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Quantifying Methane Leak Emissions by Fused Airborne Imaging Spectroscopy with in Situ Surface Mobile and Airborne Observations of a California Producing Oil Field

Methane (CH4) emission budgets remain uncertain and are projected to grow as oil and gas production from short-lived wells increases and their subsequent transport through aging gas distribution networks. Orders-of-magnitude variations in temporal, spatial, and emission scales present a key challenge to leak detection and quantification. Also, the probability distributions for large and stochastic, leaky systems such as geological reservoirs (by natural migration-seeps) and petroleum production from those reservoirs remain largely unknown, needed to address current approach limitations. The scale of many petroleum systems favors remote sensing, but the sensitivity of such systems often precludes detection of weak emissions. Consequently, an accurate evaluation requires that the relative contribution from the emission "tails" of small leaks also be quantified, which is best carried out using high-sensitivity in situ methods. Fusion of remote sensing and in situ approaches leverages complementary capabilities to address these limitations. We show results from mobile surface (AMOG) and airborne in situ (AJAX) and thermal-infrared (TIR) hyperspectral imaging spectroscopy (Mako) data applied to a producing oil field in the California Central Valley near Bakersfield. AMOG is an automobile-based mobile lab that measures 13 trace gases, aerosol size distributions and vertical profiles, 3D winds and other meteorology, and atmospheric column measurements by solar spectroscopy at highway speeds. AJAX measures 5 trace gases and 3D winds at ~140 m/s. Mako is a broad-area TIR imaging spectrometer that can discriminate multiple gases present in each pixel acquired. In situ-derived, total field emissions were 31±16 Gg/yr CH4. This was compared with Mako-derived emissions from all plumes identified across the study site. We found that super-emitters were not the dominant emissions mode and the spatial pattern of plume locations from production infrastructure was correlated to geological structures.

Leifer, Ira↗
NASA NTRS1981

Representative equations for the thermodynamic and transport properties of fluids near the gas-liquid critical point

A survey is presented of representative equations for various thermophysical properties of fluids in the critical region. Representative equations for the transport properties are included. Semi-empirical modifications of the theoretically predicted asymtotic critical behavior that yield simple and practical representations of the fluid properties in the critical region are emphasized.

Sengers, J. V.↗
NASA NTRS2018

Collisionless Relaxation of the Ion Ring Distribution in Space Plasma

Energetic processes often produce transversely-heated angular distributions of the magnetized core (lowest energy) plasma. This characteristic is found in solar wind ion pickup, resulting from cometary or interstellar gas ionization, in Earths' ionosphere, and with hot ions formed around the Space Transportation System during gas releases. We investigate the thermalization of O+ ion pickup using the 2.5D hybrid simulation method (with fluid electrons and kinetic ions) of the ion pickup (ring) distributions, formed in the auroral ionosphere, with a range of ring velocities and thermal to magnetic pressure ratios. We find that in the unstable collisonless regime the anisotropy of the non-thermal distribution produces the ion-cyclotron instability, and the nonlinear relaxation is accompanied by wave-particle scattering that results in an emitted power of EMIC waves. We conclude that ionospheric pickup thermalization is slow due to the small ring speed compared to the thermal and Alfven speeds, while in the solar wind and other space plasmas regions with larger ion-ring velocity the collisionless relaxation and thermalization is rapid in terms of O+ ion gyro-period.

Ofman, Leon↗
NASA NTRSDate not supplied

True Zero Emission Electric Aircraft Propulsion Transport Technology

This work establishes and describes a new electric aircraft propulsion technology category for achieving true zero greenhouse gas emission with transport aircraft. This new category is enabled by a recently invented Closed Strayton Quad Generator and recently developed megawatt-scale electric propulsor motors that enable staged contra-rotating ducted fans in a single nacelle. After a brief review of the existing state of practice, a new electric aircraft propulsion system is described that is quiet, clean, efficient, reliable, safe and supports the global transition from jet fuel and sustainable aviation fuel to future green hydrogen fuel with the goal of achieving truly zero impact on the environment. A detailed design of this propulsion system is presented along with a performance and mass comparison to current state of practice.

Closed↗
NASA NTRSDate not supplied

True Zero Emission Electric Aircraft Propulsion Transport Technology

This work establishes and describes a new electric aircraft propulsion technology category for achieving true zero greenhouse gas emission with transport aircraft. This new category is enabled by a recently invented Closed Strayton Quad Generator and recently developed megawatt-scale electric propulsor motors that enable staged contra-rotating ducted fans in a single nacelle. After a brief review of the existing state of practice, a new electric aircraft propulsion system is described that is quiet, clean, efficient, reliable, safe and supports the global transition from jet fuel and sustainable aviation fuel to future green hydrogen fuel with the goal of achieving truly zero impact on the environment. A detailed design of this propulsion system is presented along with a performance and mass comparison to current state of practice.

Closed↗
NASA NTRS1983

Analysis of STS-3 Get Away Special (GAS) flight data and vibration specification for gas payloads

During the Space Transportation System (STS)-3 mission, a Get Away Special (GAS) canister was flown. In order to determine the flight environment for GAS payloads, triaxial accelerometers and a microphone were installed inside the GAS canister. Data from these accelerometers and the microphone were analyzed. The microphone data is presented as overall sound pressure level (SPL) and one-third octave band time history plots. And the accelerometer data is provided in the forms of instantaneous time history, RMS time history and power spectral density plots. Also based on this flight data, vibration test specification for GAS payloads was developed and the recommended specification is presented here.

Talapatra, D. C.↗
NASA NTRS1997

Bulk Growth of Wide Band Gap II-VI Compound Semiconductors by Physical Vapor Transport

The mechanism of physical vapor transport of II-VI semiconducting compounds was studied both theoretically, using a one-dimensional diffusion model, as well as experimentally. It was found that the vapor phase stoichiometry is critical in determining the vapor transport rate. The experimental heat treatment methods to control the vapor composition over the starting materials were investigated and the effectiveness of the heat treatments was confirmed by partial pressure measurements using an optical absorption technique. The effect of residual (foreign) gas on the transport rate was also studies theoretically by the diffusion model and confirmed experimentally by the measurements of total pressure and compositions of the residual gas. An in-situ dynamic technique for the transport rate measurements and a further extension of the technique that simultaneously measured the partial pressures and transport rates were performed and, for the first time, the experimentally determined mass fluxes were compared with those calculated, without any adjustable parameters, from the diffusion model. Using the information obtained from the experimental transport rate measurements as guideline high quality bulk crystal of wide band gap II-VI semiconductor were grown from the source materials which undergone the same heat treatment methods. The grown crystals were then extensively characterized with emphasis on the analysis of the crystalline structural defects.

Su, Ching-Hua↗
NASA NTRS1997

Bulk Growth of Wide Band Gap II-VI Compound Semiconductors by Physical Vapor Transport

The mechanism of physical vapor transport of II-VI semiconducting compounds was studied both theoretically, using a one-dimensional diffusion model, as well as experimentally. It was found that the vapor phase stoichiometry is critical in determining the vapor transport rate. The experimental heat treatment methods to control the vapor composition over the starting materials were investigated and the effectiveness of the heat treatments was confirmed by partial pressure measurements using an optical absorption technique. The effect of residual (foreign) gas on the transport rate was also studies theoretically by the diffusion model and confirmed experimentally by the measurements of total pressure and compositions of the residual gas. An in-situ dynamic technique for the transport rate measurements and a further extension of the technique that simultaneously measured the partial pressures and transport rates were performed and, for the first time, the experimentally determined mass fluxes were compared with those calculated, without any adjustable parameters, from the diffusion model. Using the information obtained from the experimental transport rate measurements as guideline high quality bulk crystal of wide band gap II-VI semiconductor were grown from the source materials which undergone the same heat treatment methods. The grown crystals were then extensively characterized with emphasis on the analysis of the crystalline structural defects.

Su, Ching-Hua↗
NASA NTRS2008

Fan Performance Testing and Oxygen Compatibility Assessment Results for Future Space Suit Life Support Systems

An advanced portable life support system (PLSS) for the space suit will require a small, robust, and energy-efficient system to transport the ventilation gas through the space suit for lunar Extravehicular Activity (EVA) operations. A trade study identified and compared ventilation transport technologies in commercial, military, and space applications to determine which technologies could be adapted for EVA use. Based on the trade study results, five commercially available, 24volt fans were selected for performance testing at various pressures and flow rates. Measured fan parameters included fan delta-pressures, input voltages, input electrical currents, and in some cases motor windings electrical voltages and currents. In addition, a follow-on trade study was performed to identify oxygen compatibility issues and assess their impact on fan design. This paper outlines the results of the fan performance characterization testing, as well as the results from the oxygen compatibility assessment.

Jennings, Mallory A.↗
NASA NTRS2009

Fan Performance Testing and Oxygen Compatibility Assessment Results for Future Space Suit Life Support Systems

An advanced portable life support system (PLSS) for the space suit will require a small, robust, and energyefficient system to transport the ventilation gas through the space suit for lunar Extravehicular Activity (EVA) operations. A trade study identified and compared ventilation transport technologies in commercial, military, and space applications to determine which technologies could be adapted for EVA use. Based on the trade study results, five commercially available, 24-volt fans were selected for performance testing at various pressures and flow rates. Measured fan parameters included fan delta-pressures, input voltages, input electrical currents, and in some cases motor windings electrical voltages and currents. In addition, a follow-on trade study was performed to identify oxygen compatibility issues and assess their impact on fan design. This paper outlines the results of the fan performance characterization testing, as well as the results from the oxygen compatibility assessment.

Paul, Heather L.↗
NASA NTRS1991

Chemical vapor deposition modeling: An assessment of current status

The shortcomings of earlier approaches that assumed thermochemical equilibrium and used chemical vapor deposition (CVD) phase diagrams are pointed out. Significant advancements in predictive capabilities due to recent computational developments, especially those for deposition rates controlled by gas phase mass transport, are demonstrated. The importance of using the proper boundary conditions is stressed, and the availability and reliability of gas phase and surface chemical kinetic information are emphasized as the most limiting factors. Future directions for CVD are proposed on the basis of current needs for efficient and effective progress in CVD process design and optimization.

Gokoglu, Suleyman A.↗
NASA NTRS2009

Integrated High Payoff Rocket Propulsion Technology (IHPRPT) SiC Recession Model

SiC stability and recession rates were modeled in hydrogen/oxygen combustion environments for the Integrated High Payoff Rocket Propulsion Technology (IHPRPT) program. The IHPRPT program is a government and industry program to improve U.S. rocket propulsion systems. Within this program SiC-based ceramic matrix composites are being considered for transpiration cooled injector faceplates or rocket engine thrust chamber liners. Material testing under conditions representative of these environments was conducted at the NASA Glenn Research Center, Cell 22. For the study described herein, SiC degradation was modeled under these Cell 22 test conditions for comparison to actual test results: molar mixture ratio, MR (O2:H2) = 6, material temperatures to 1700 C, combustion gas pressures between 0.34 and 2.10 atm, and gas velocities between 8,000 and 12,000 fps. Recession was calculated assuming rates were controlled by volatility of thermally grown silica limited by gas boundary layer transport. Assumptions for use of this model were explored, including the presence of silica on the SiC surface, laminar gas boundary layer limited volatility, and accuracy of thermochemical data for volatile Si-O-H species. Recession rates were calculated as a function of temperature. It was found that at 1700 C, the highest temperature considered, the calculated recession rates were negligible, about 200 m/h, relative to the expected lifetime of the material. Results compared favorably to testing observations. Other mechanisms contributing to SiC recession are briefly described including consumption of underlying carbon and pitting. A simple expression for liquid flow on the material surface was developed from a one-dimensional treatment of the Navier-Stokes Equation. This relationship is useful to determine under which conditions glassy coatings or thermally grown silica would flow on the material surface, removing protective layers by shear forces. The velocity of liquid flow was found to depend on the gas velocity, the viscosity of gas and liquid, as well as the thickness of the gas boundary layer and the liquid layer. Calculated flow rates of a borosilicate glass coating compared well to flow rates observed for this coating tested on a SiC panel in Cell 22.

Opila, E. J.↗
NASA NTRS1989

Theoretical studies in support of the 3M-vapor transport (PVTOS-) experiments

Results are reported for a preliminary theoretical study of the coupled mass-, momentum-, and heat-transfer conditions expected within small ampoules used to grow oriented organic solid (OS-) films, by physical vapor transport (PVT) in microgravity environments. It is show that previous studies made restrictive assumptions (e.g., smallness of delta T/T, equality of molecular diffusivities) not valid under PVTOS conditions, whereas the important phenomena of sidewall gas creep, Soret transport of the organic vapor, and large vapor phase supersaturations associated with the large prevailing temperature gradients were not previously considered. Rational estimates are made of the molecular transport properties relevant to copper-phthalocyanine monomeric vapor in a gas mixture containing H2(g) and Xe(g). Efficient numerical methods have been developed and are outlined/illustrated here to making steady axisymmetric gas flow calculations within such ampoules, allowing for realistic realistic delta T/T(sub)w-values, and even corrections to Navier-Stokes-Fourier 'closure' for the governing continuum differential equations. High priority follow-on studies are outlined based on these new results.

Rosner, Daniel E.↗