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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Simulation of a Synthetic Jet in Quiescent Air Using TLNS3D Flow Code

Although the actuator geometry is highly three-dimensional, the outer flowfield is nominally two-dimensional because of the high aspect ratio of the rectangular slot. For the present study, this configuration is modeled as a two-dimensional problem. A multi-block structured grid available at the CFDVAL2004 website is used as a baseline grid. The periodic motion of the diaphragm is simulated by specifying a sinusoidal velocity at the diaphragm surface with a frequency of 450 Hz, corresponding to the experimental setup. The amplitude is chosen so that the maximum Mach number at the jet exit is approximately 0.1, to replicate the experimental conditions. At the solid walls zero slip, zero injection, adiabatic temperature and zero pressure gradient conditions are imposed. In the external region, symmetry conditions are imposed on the side (vertical) boundaries and far-field conditions are imposed on the top boundary. A nominal free-stream Mach number of 0.001 is imposed in the free stream to simulate incompressible flow conditions in the TLNS3D code, which solves compressible flow equations. The code was run in unsteady (URANS) mode until the periodicity was established. The time-mean quantities were obtained by running the code for at least another 15 periods and averaging the flow quantities over these periods. The phase-locked average of flow quantities were assumed to be coincident with their values during the last full time period.

Vatsa, Veer N.↗
NASA NTRS1973

ERTS-1 anomalous dark patches

The author has identified the following significant results. Through combined use of imagery from ERTS-1 and NOAA-2 satellites was found that when the sun elevation exceeds 55 degrees, the ERTS-1 imagery is subject to considerable contamination by sunlight even though the actual specular point is nearly 300 nautical miles from nadir. Based on sea surface wave slope information, a wind speed of 10 knots will theoretically provide approximately 0.5 percent incident solar reflectance under observed ERTS multispectral scanner detectors. This reflectance nearly doubles under the influence of a 20 knot wind. The most pronounced effect occurs in areas of calm water where anomalous dark patches are observed. Calm water at distances from the specular point found in ERTS scenes will reflect no solar energy to the multispectral scanner, making these regions stand out as dark areas in all bands in an ocean scene otherwise comprosed by a general diffuse sunlight from rougher ocean surfaces. Anomalous dark patches in the outer parts of the glitter zones may explain the unusual appearance of some scenes.

Strong, A. E.↗
NASA NTRS2004

Design Analysis and Thermo-Mechanical Fatigue of a Polyimide Composite for Combustion Chamber Support

Polyimide composites are being evaluated for use in lightweight support structures designed to preserve the ideal flow geometry within thin shell combustion chambers of future space launch propulsion systems. Principles of lightweight design and innovative manufacturing techniques have yielded a sandwich structure with an outer face sheet of carbon fiber polyimide matrix composite. While the continuous carbon fiber enables laminated skin of high specific stiffness; the polyimide matrix materials ensure that the rigidity and durability is maintained at operation temperatures of 316 C. Significant weight savings over all metal support structures are expected. The protypical structure is the result of ongoing collaboration, between Boeing and NASA-GRC seeking to introduce polyimide composites to the harsh environmental and loads familiar to space launch propulsion systems. Design trade analyses were carried out using relevant closed form solutions, approximations for sandwich beams/panels and finite element analysis. Analyses confirm the significant thermal stresses exist when combining materials whose coefficients of thermal expansion (CTEs) differ by a factor of about 10 for materials such as a polymer composite and metallic structures. The ramifications on design and manufacturing alternatives are reviewed and discussed. Due to stringent durability and safety requirements, serious consideration is being given to the synergistic effects of temperature and mechanical loads. The candidate structure operates at 316 C, about 80% of the glass transition temperature T(sub g). Earlier thermomechanical fatigue (TMF) investigations of chopped fiber polyimide composites made this near to T(sub g), showed that cyclic temperature and stress promoted excessive creep damage and strain accumulation. Here it is important to verify that such response is limited in continuous fiber laminates.

Thesken, J. C.↗
NASA NTRS2016

Prompt Acceleration of Magnetospheric Electrons to Ultrarelativistic Energies by the 17 March 2015 Interplanetary Shock

Trapped electrons in Earth's outer Van Allen radiation belt are influenced profoundly by solar phenomena such as high-speed solar wind streams, coronal mass ejections (CME), and interplanetary (IP) shocks. In particular, strong IP shocks compress the magnetosphere suddenly and result in rapid energization of electrons within minutes. It is believed that the electric fields induced by the rapid change in the geomagnetic field are responsible for the energization. During the latter part of March 2015, a CME impact led to the most powerful geomagnetic storm (minimum Dst = −223 nT at 17 March, 23 UT) observed not only during the Van Allen Probe era but also the entire preceding decade. Magnetospheric response in the outer radiation belt eventually resulted in elevated levels of energized electrons. The CME itself was preceded by a strong IP shock whose immediate effects vis-a-vis electron energization were observed by sensors on board the Van Allen Probes. The comprehensive and high-quality data from the Van Allen Probes enable the determination of the location of the electron injection, timescales, and spectral aspects of the energized electrons. The observations clearly show that ultrarelativistic electrons with energies E greater than 6 MeV were injected deep into the magnetosphere at L approximately equals 3 within about 2 min of the shock impact. However, electrons in the energy range of approximately equals 250 keV to approximately equals 900 keV showed no immediate response to the IP shock. Electric and magnetic fields resulting from the shock-driven compression complete the comprehensive set of observations that provide a full description of the near-instantaneous electron energization.

radiation belts↗
DOE OSTI2025

Techno-economic feasibility of borehole thermal energy storage system connected to geothermal heat pumps for seasonal heating load of two buildings in Fairbanks, Alaska

Borehole thermal energy storage (BTES) is an effective solution for managing imbalanced heating and cooling loads in cold regions. This study evaluated the long-term feasibility of a BTES system in the Fairbanks area, Alaska, through building energy modeling, resource characterization, and numerical modeling. The system was designed to store waste heat from a nearby coal power plant during summer and provide thermal energy during winter to geothermal heat pumps supplying heating loads in two buildings. Heating load profiles were modeled for the buildings using EnergyPlus, and the results indicated the annual heating load was 5.6 times greater than the cooling load. 40 borehole heat exchangers were pre-designed approximately 100 m away from the two buildings in terms of land availability and regulatorily optimized depth. The 20-year performance of the designed BTES system under two operational scenarios—one with a 5-year preheating period and one without—was numerically modeled using subsurface temperature and properties characterized through the literature review and thermal response tests. Both scenarios demonstrated that the BTES has the capacity to fully cover the heating loads in the two buildings throughout the 20-year lifetime. Production temperatures at central wells were 33 % higher on average than at outer wells in both scenarios. The 5-year preheating period increased subsurface and extraction temperatures, and correspondingly annual average and total thermal energy production was higher for 8 years than in the scenario without the preheating period. These results highlight the long-term reliability and sustainability of the BTES system in meeting heating demands over its lifetime, with the preheating period offering potential performance improvements. Implementing the BTES system in cold regions with high heating demand, such as Fairbanks, Alaska, could provide a long-term, sustainable energy solution for managing imbalanced heating and cooling loads.

15 GEOTHERMAL ENERGY↗
NASA NTRS1991

New observations of the low frequency interplanetary radio emissions

Recent Voyager 1 observations reveal reoccurrences of the low frequency interplanetary radio emissions. Three of the new events are weak transient events which rise in frequency from the range of 2-2.5 kHz to about 3 kHz with drift rates of approximately 1.5 kHz/year. The first of the transient events begins in mid-1989 and the more recent pair of events both were first detected in late 1991. In addition, there is an apparent onset of a 2-kHz component of the emission beginning near day 70 of 1991. The new transient emissions are barely detectable on Voyager 1 and are below the threshold of detectability on Voyager 2, which is less sensitive than Voyager 1. The new activity provides new opportunities to test various theories of the triggering, generation, and propagation of the outer heliospheric radio emissions and may signal a response of the source of the radio emissions to the increased solar activity associated with the recent peak in the solar cycle.

Kurth, W. S.↗
DOE OSTI2016

Materials Assessment of Insulating Foam in the 9977 Shipping Package for Long-Term Storage - Annual Report

The 9977 shipping package is being evaluated for long-term storage applications in the K-Area Complex (KAC) with specific focus on the packaging foam material. A rigid closed cell polyurethane foam, LAST-A-FOAM® FR-3716, produced by General Plastics Manufacturing Company is sprayed and expands to fill the void between the inner container and the outer shell of the package. The foam is sealed in this annular space and is not accessible. During shipping and storage, the foam experiences higher than ambient temperatures from the heat generated by nuclear material within the package creating the potential for degradation of the foam. A series of experiments is underway to determine the extent of foam degradation. Foam samples of three densities have been aging at elevated temperatures 160 °F, 160 °F + 50% relative humidity (RH), 185 °F, 215 °F, and 250 °F since 2014. Samples were periodically removed and tested. After approximately 80 weeks, samples conditioned at 160 °F, 160 °F + 50% RH, and 185 °F have retained initial property values while samples conditioned at 215 °F have reduced intumescence. Samples conditioned at 250 °F have shown the most degradation, loss of volume, mass, absorbed energy under compression, intumescence, and increased flammability. Based on the initial data, temperatures up to 185 °F have not yet shown an adverse effect on the foam properties and it is recommended that exposure of FR-3716 foam to temperatures in excess of 250 °F be avoided or minimized. Testing will continue beyond the 96 week mark. This will provide additional data to help define the long-term behavior for the lower temperature conditions. Additional testing will be pursued in an attempt to identify transition points (threshold times and temperatures) at the higher temperatures of interest, as well as possible benefits of aging within the relatively oxygen-free environment the foam experiences inside the 9977 shipping package.

36 MATERIALS SCIENCE↗
NASA NTRS1977

Optimal low-thrust takeoff from an orbit about an oblate planet

Future space missions to the outer planets may depend upon the use of low-thrust propulsion systems. As these planets are decidedly oblate, the question of the effect of that oblateness on a low-thrust trajectory is of some interest. In this paper the problem of optimal energy increase is attacked under the assumption that the coefficients for the second zonal harmonic, and the nondimensional thrust acceleration are the same order of magnitude. By means of a two-variable asymptotic expansion technique, a near optimal control program is generated and the first-order uniformly valid approximation for the corresponding trajectory is obtained. Tangential thrust is shown to be a good near-optimal thrust program even in the presence of oblateness effects. The optimal control program is found to be oscillatory and quite similar to the optimal control for energy increase in an inverse square gravitational field.

Jacobson, R. A.↗
NASA NTRS1981

Advanced solar concentrator: Preliminary and detailed design

A single reflection point focusing two-axis tracking paraboloidal dish with a reflector aperture diameter of approximately 11 m has a reflective surface made up of 64 independent, optical quality gores. Each gore is a composite of a thin backsilvered mirror glass face sheet continuously bonded to a contoured substrate of lightweight, rigid cellular glass. The use of largely self-supporting gores allows a significant reduction in the weight of the steel support structure as compared to alternate design concepts. Primary emphasis in the preliminary design package for the low-cost, low-weight, mass producible concentrator was placed on the design of the higher cost subsystems. The outer gore element was sufficiently designed to allow fabrication of prototype gores.

Bell, D. M.↗
NASA NTRS1995

Heliospheric 2-3 kHz radio emissions and their relationship to large Forbush decreases

Two intense heliospheric 2-3 kHz radio emission events have been observed by Voyagers 1 and 2, the first in 1983-84 and the second in 1992-93. These radio emission events occurred about 400 days after large Forbush decreases in mid-1982 and mid-1991. Since Forbush decreases are indicative of a strong interplanetary shock propagating outward through the heliosphere, this temporal relationship provides strong evidence that the radio emissions are triggered by the interaction of a shock with one of the outer boundaries of the heliosphere. From the travel time and the known speed of the shock, the distance to the interaction region can be estimated and is well beyond 100 AU. At this great distance the plasma frequency at the terminal shock (100 to 200 Hz) is believed to be too small to explain the observed emission frequencies, which extend up to 3.6 kHz. For this reason, we have proposed that the interaction takes place at or near the heliopause, where remote sensing measurements show that the plasma frequency is in a suitable range (approximately 3 kHz) for explaining the radio emission. From the travel time and shock propagation speed, the radial distance to the heliopause has been calculated for various candidate solar events. After taking into account the likely deceleration of the shock, the heliopause is estimated to be in the range from about 110 to 160 AU.

Gurnett, D. A.↗
NASA NTRS2017

Asymmetric Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3

The youngest Galactic supernova remnant (SNR) G1.9+0.3, produced by a (probable) SN Ia that exploded approximately 1900 CE, is strongly asymmetric at radio wavelengths, much brighter in the north, but bilaterally symmetric in X-rays. We present the results of X-ray expansion measurements that illuminate the origin of the radio asymmetry. We confirm the mean expansion rate (2011-2015) of 0.58% per yr, but large spatial variations are present. Using the nonparametric 'Demons' method, we measure the velocity field throughout the entire SNR, finding that motions vary by a factor of 5, from 0.''09 to 0.''44 per yr. The slowest shocks are at the outer boundary of the bright northern radio rim, with velocities v(sub s) as low as 3600 km per sec (for an assumed distance of 8.5 kpc), much less than v(sub s) = 12,000-13,000 km per sec along the X-ray-bright major axis. Such strong deceleration of the northern blast wave most likely arises from the collision of SN ejecta with a much denser than average ambient medium there. This asymmetric ambient medium naturally explains the radio asymmetry. In several locations, significant morphological changes and strongly nonradial motions are apparent. The spatially integrated X-ray flux continues to increase with time. Based on Chandra observations spanning 8.3 yr, we measure its increase at 1.3% +/- 0.8% per yr. The SN ejecta are likely colliding with the asymmetric circumstellar medium ejected by the SN progenitor prior to its explosion.

ISM: individual objects (G1.9+0.3) ISM: individual↗
DOE OSTI2021

A Multi-criteria CCUS Screening Evaluation of the Gulf of Mexico, USA - Supplementary Data

The Wendt et al. study aims to incorporate multiple and disparate carbon capture, utilization, and storage (CCUS) decision-making criteria into a systematic, quantitative analytical approach to help identify areas with potentially high suitability to serve as offshore CO2 storage or EOR regions. Spatially-distributed data from publicly-available sources within the Gulf of Mexico (GOM) study area (limited to federal waters; state waters were not evaluated) was compiled using the U.S. Department of Energy's (DOE) National Energy Technology Laboratory (NETL) Cumulative Spatial Impact Layers™ (CSIL) tool to easily aggregate data based on evenly-distributed grids across the study region set at a resolution of approximately 25 square miles (65 square kilometers). The data included in this Microsoft Excel™ workbook provide the aggregated scores for each grid point across the study domain as well the weighting for each criterion under the four scenarios evaluated.

CCUS↗
DOE OSTI2016

Composite electron propagator methods for calculating ionization energies

Accurate ionization energies of molecules may be determined efficiently with composite electron-propagator (CEP) techniques. These methods estimate the results of a calculation with an advanced correlation method and a large basis set by performing a series of more tractable calculations in which large basis sets are used with simpler approximations and small basis sets are paired with more demanding correlation techniques. The performance of several CEP methods, in which diagonal, second-order electron propagator results with large basis sets are combined with higher-order results obtained with smaller basis sets, has been tested for the ionization energies of closed-shell molecules from the G2 set. Useful compromises of accuracy and computational efficiency employ complete-basis-set extrapolation for second-order results and small basis sets in third-order, partial third-order, renormalized partial-third order, or outer valence Green’s function calculations. Analysis of results for vertical as well as adiabatic ionization energies leads to specific recommendations on the best use of regular and composite methods. Results for 22 organic molecules of interest in the design of photovoltaic devices, benzo[a]pyrene, Mg-octaethylporphyrin, and C{sub 60} illustrate the capabilities of CEP methods for calculations on large molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1993

Imaging of the Wolf-Rayet galaxy He 2-10

We present B, V, and emission-line CCD images of the Wolf-Rayet galaxy He 2-10. The broad band images reveal the galaxy to consist of two starburst regions at the center of an elliptical stellar envelope about 10 times their size, with a major axis diameter of approximately 3.8 kpc. Previous imaging detected only the starburst regions, leading to the erroneous description of the object as an interacting pair. Morphologically, He 2-10 resembles the majority of blue compact dwarf galaxies (BCDGs), some of which also show Wolf-Rayet features in their spectra. The lack of nearby neighbors to He 2-10 suggests that its star formation is proceeding stochastically, rather than as the result of interaction, and its morphological similarity to other BCDGs suggests that all such galaxies may pass through a Wolf-Rayet phase. The similarity of the outer regions of He 2-10 and other BCDGs to normal dwarf ellipticals also supports models in which the former evolve into the latter.

Corbin, Michael R.↗
NASA NTRS1999

Peroxide-modified titanium dioxide: a chemical analog of putative Martian soil oxidants

Hydrogen peroxide chemisorbed on titanium dioxide (peroxide-modified titanium dioxide) is investigated as a chemical analog to the putative soil oxidants responsible for the chemical reactivity seen in the Viking biology experiments. When peroxide-modified titanium dioxide (anatase) was exposed to a solution similar to the Viking labeled release (LR) experiment organic medium, CO2 gas was released into the sample cell headspace. Storage of these samples at 10 degrees C for 48 hr prior to exposure to organics resulted in a positive response while storage for 7 days did not. In the Viking LR experiment, storage of the Martian surface samples for 2 sols (approximately 49 hr) resulted in a positive response while storage for 141 sols essentially eliminated the initial rapid release of CO2. Heating the peroxide-modified titanium dioxide to 50 degrees C prior to exposure to organics resulted in a negative response. This is similar to, but not identical to, the Viking samples where heating to approximately 46 degrees C diminished the response by 54-80% and heating to 51.5 apparently eliminated the response. When exposed to water vapor, the peroxide-modified titanium dioxide samples release O2 in a manner similar to the release seen in the Viking gas exchange experiment (GEx). Reactivity is retained upon heating at 50 degrees C for three hours, distinguishing this active agent from the one responsible for the release of CO2 from aqueous organics. The release of CO2 by the peroxide-modified titanium dioxide is attributed to the decomposition of organics by outer-sphere peroxide complexes associated with surface hydroxyl groups, while the release of O2 upon humidification is attributed to more stable inner-sphere peroxide complexes associated with Ti4+ cations. Heating the peroxide-modified titanium dioxide to 145 degrees C inhibited the release of O2, while in the Viking experiments heating to this temperature diminished but did not eliminated the response. Although the thermal stability of the titanium-peroxide complexes in this work is lower than the stability seen in the Viking experiments, it is expected that similar types of complexes will form in titanium containing minerals other than anatase and the stability of these complexes will vary with surface hydroxylation and mineralogy.

Review↗
NASA NTRS2007

Investigation of MMOD Impact on Shuttle Payload Bay Door Radiator

Post flight inspections on the Space Shuttle Atlantis conducted after the STS-115 mission revealed a 0.11 inch (2.8 mm) hole in the outer facesheet of the starboard payload bay door radiator panel #4. This hole is the possible result of micrometeoroid/orbiting debris (MMOD) impact. The payload bay door radiators in this region are 0.5 inch (12.7 mm) thick aluminum honeycomb with 0.011 in (0.279 mm) thick aluminum facesheets topped with 0.005 in (0.127 mm) silver-Teflon tape. Inner facesheet damage included a 0.267 in (6.78 mm) long through crack with measurable deformation in the area of 0.2 in (5.1 mm). There was also a 0.031 in (0.787 mm) diameter hole in the rear facesheet. A large approximately 1 in (25 mm) diameter region of honeycomb was also destroyed. Since the radiators are located on the inside of the shuttle payload bay doors which are closed during ascent and reentry, the damage could only have occurred during the on-orbit portion of the mission. This paper will document the data collected from the impact site and will include results of the SEM/EDX analysis. Evidence will be presented that suggests a source of the impact as well as an analysis of the impact site features that indicate projectile directionality. Results of hypervelocity impact testing on representative samples in an attempt to simulate the impact event will be presented and discussed. Finally, the results of a study showing the regions of the orbiter vehicle that would be vulnerable to an equivalent projectile will be given.

Hyde, J. L.↗
NASA NTRS2017

The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

The Wide-field Infrared Survey Explorer (WISE) is a powerful tool for finding nearby brown dwarfs and searching for new planets in the outer solar system, especially with the incorporation of NEOWISE and NEOWISE Reactivation data. However, so far, searches for brown dwarfs in WISE data have yet to take advantage of the full depth of the WISE images. To efficiently search this unexplored space via visual inspection, we have launched anew citizen science project, called "Backyard Worlds: Planet 9," which asks volunteers to examine short animations composed of difference images constructed from time-resolved WISE co adds. We report the first new substellar object discovered by this project, WISEA J110125.95+540052.8, a T5.5 brown dwarf located approximately 34 pc from the Sun with a total proper motion of approx.0. "7/ yr. WISEA J110125.95+540052.8 has a WISE W2 magnitude of W2 = 15.37+/- 0.09; our sensitivity to this source demonstrates the ability of citizen scientists to identify moving objects via visual inspection that are 0.9 mag fainter than the W2 single-exposure sensitivity, a threshold that has limited prior motion-based brown dwarf searches with WISE.

Wide-field Infrared Survey Explorer (WISE)↗
DOE OSTI2022

Data Mining – Image Analysis of Radiography for Zr Redistribution

The research effort described in this report represents a first attempt to investigate the radial redistribution of Zr in ternary fuel alloys U-xPu-10Zr (x = 0, 8, 19) irradiated in the in-reactor fuel experiments during the operation of the U.S. Department of Energy’s (DOE’s) Experimental Breeder Reactor II (EBR-II) at Idaho National Laboratory (INL) using methods of image processing on post-irradiation neutron radiographs. Approximately 130,000 metal fuel pins were irradiated in EBR-II during its 30 years of operation to develop and characterize existing and prospective fuels. For many of the metal fuel irradiation experiments, neutron radiography imaging was performed historically now allowing application of modern image analysis techniques to characterize fuel behavior, such as fuel swelling, fluff formation, and now, fuel alloy constituent redistribution. The redistribution of fuel components depends on the temperature field, radially, within the fuel. Specifically, Zr is expected to redistribute radially towards the center of the pin, as well as towards the outer zones. Currently, direct imaging of a pin cross-section through optical methods or scanning electron microscopy (SEM) is used to study the constituents’ redistribution, which is very time-consuming and can only be applied to a limited number of pins. An automated image processing technique allowing for the investigation of fuel radial redistribution zones would significantly accelerate data analysis. In general, if the fuel temperature is hot enough, three redistribution zones are expected, corresponding to the main fuel components (e.g., U, Pu, Zr). While more assessment will be performed in fiscal year (FY)-2023, it seems possible to differentiate the pins according to their fuel composition using image analysis techniques on neutron radiographs of metallic fuel pins based on the analysis to date.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗