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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Basal hydraulic conditions of Ice Stream B

Fifteen boreholes have been drilled to the base of Ice Stream B in the vicinity of UpB Camp. The boreholes are spread over an area of about 500 x 1000 m. Several till cores were retrieved from the bottom of the 1000-m-deep holes. Laboratory tests using a simple shear box revealed a yield strength of basal till of 2 kPa. This agrees well with in-situ measurements using a shear vane. Since the average basal shear stress of Ice Stream B with a surface slope of 0.1 degree is about 20 kPa, the ice stream cannot be supported by till that weak. Additional support for this conclusion comes from the basal water pressure that has been measured in all boreholes as soon as the hot water drill reached bottom. In several boreholes, the water pressure has been continuously monitored; in two of them, over several years. The water pressure varies but stays within 1 bar of flotation where ice overburden pressure and water pressure are equal. The ratio of water and overburden pressure lies between 0.986 and 1.002. This is an extremely high value as compared to other fast-moving ice masses; e.g., Variegated Glacier in surge has a ratio of 0.8, and Columbia Glacier - a fast-moving tidewater glacier - has a ratio of 0.9. It implies that water flow under the glacier occurs in a thin film and not in conduits that would drain away water too rapidly. It also implies that basal sliding must be very effective. Water flow under the glacier was measured in a salt-injection experiment where a salt pulse was released at the bottom of a borehole while 60 m down-glacier, the electrical resistance was measured between two other boreholes. A flow velocity of 7 mm/s was obtained.

Engelhardt, Hermann↗
NASA NTRS1999

The SOHO-Stellar Connection

I discusses practical aspects of the so-called "solar-stellar" connection; namely, the fundamental principles, the tools at the disposal of the stellar astronomer, and a few recent examples of the connection in action. I provide an overall evolutionary context for coronal activity, calling attention to the very different circumstances of low mass main sequence stars like the Sun, which are active mainly early in their lives; compared with more massive stars, whose coronally active phase occurs near the end of their lives, during their brief incursion into the cool half of the Hertzsprung-Russell diagram as yellow and then red giants. On the instrumental slide, I concentrate primarily on spectroscopy, in the ultraviolet and X-ray bands where coronae leave their most obvious signatures. I present an early glimpse of the type of moderate resolution spectra we can expect from the recently launched Chandra observatory, and contemporaneous HST STIS high-resolution UV measurements of the CXO calibration star Capella (alpha Aur; G8 III + G1 III). I compare STIS spectra of solar-type dwarfs-zeta Dor (F7 V), an active coronal source; and alpha Cen A (G2 V), a near twin of the Sun-to a trace obtained with the SOHO SUMER imaging UV spectrometer. I also compare STIS line profiles of the active coronal dwarf to the corresponding features in the mixed-activity "hybrid-chromosphere" bright giant alpha TrA (K2 II) and the archetype "noncoronal" red giant Arcturus (alpha Boo; K2 III). The latter shows dramatic evidence for a "cool absorber" in its outer atmosphere that is extinguishing the "hot lines" (like Si IV lambda1393 and N V lambda1238) below about 1500 A, probably through absorption in the Si I lambda1525 and C I lambda1240 photoionization continua. The disappearance of coronae across the "Linsky-Haisch" dividing line near K1 III thus apparently is promoted by a dramatic overturning in the outer atmospheric structure, namely the coronae of the red giants seem to lie beneath their extended chromospheres, rather than outside as in the Sun. I then discuss an intriguing long-slit STIS low-resolution observation of an X-ray active late-A dwarf in the nearby Hyades cluster: the spatially resolved UV spectroscopy clearly shows that a previously unseen close companion (a dKe or dMe) likely is responsible for the coronal activity, rather than some unexplained departure of the A dwarf from its expected state of X-ray dormancy. Finally, I describe early results from a joint observing campaign involving SOHO SUMER, TRACE, and the Kitt Peak Infrared Imaging Spectrometer, conducted May 1999, to explore the dynamics of the quiet solar atmosphere through the key "magnetic transition zone" that separates the kinetically dominated deep photosphere from the magnetically dominated coronal regime. Linking spatially and temporally resolved solar properties to aspects of the averaged lineshapes (for example: widths, asymmetries, intensity ratios, and Doppler shifts) is a crucial step in carrying any physical wisdom we develop in the solar setting to the distant stars.

Ayres, Thomas R.↗
NASA NTRS2009

Rocketdyne - F-1 Saturn V First Stage Engine

Before I go into the history of F-1, I want to discuss the F-1 engine s role in putting man on the moon. The F-1 engine was used in a cluster of five on the first stage, and that was the only power during the first stage. It took the Apollo launch vehicle, which was 363 feet tall and weighed six million pounds, and threw it downrange fifty miles, threw it up to forty miles of altitude, at Mach 7. It took two and one-half minutes to do that and, in the process, burned four and one-half million pounds of propellant, a pretty sizable task. (See Slide 2, Appendix C) My history goes back to the same year I started working at Rocketdyne. That s where the F-1 had its beginning, back early in 1957. In 1957, there was no space program. Rocketdyne was busy working overtime and extra days designing, developing, and producing rocket engines for weapons of mass destruction, not for scientific reasons. The Air Force contracted Rocketdyne to study how to make a rocket engine that had a million pounds of thrust. The highest thing going at the time had 150,000 pounds of thrust. Rocketdyne s thought was the new engine might be needed for a ballistic missile, not that it was going to go on a moon shot.

Biggs, Robert↗
DOE OSTI2021

A Solution to Asymmetric Marangoni GTA Weld Behavior in a Dissimilar Chemistry Stainless Steel Joint [Slides]

Asymmetric and irregular weld morphology is an issue with the 9516 shipping container GTA weld. Observation of the weld puddle and cross sections showed the weld was biased toward the body side of the joint. This issue is attributed to a difference in the sulfur content and Marangoni fluid flow characteristics of the lid (150 ppm) and body (10 ppm) components of the weld joint. An additional contributing factor in this issue is the large difference in mass between the ½” thick lid and 1/8” thick body. A solution was developed comprised of a preliminary partial penetration weave pass across the joint intended to homogenize the sulfur content prior to the full penetration pass.

42 ENGINEERING↗
NASA NTRS2002

Carbon Nanomaterials as Reinforcements for Composites

Carbon nanomaterials including fellerenes, nanotubes (CNT) and nanofibers have been proposed for many applications. One of applications is to use the carbon nanomaterials as reinforcements for composites, especially for polymer matrices. Carbon nanotubes is a good reinforcement for lightweight composite applications due to its low mass density and high Young's modulus. Two obscures need to overcome for carbon nanotubes as reinforcements in composites, which are large quantity production and functioning the nanotubes. This presentation will discuss the carbon nanotube growth by chemical vapor deposition. In order to reduce the cost of producing carbon nanotubes as well as preventing the sliding problems, carbon nanotubes were also synthesized on carbon fibers. The synthesis process and characterization results of nanotubes and nanotubes/fibers will be discussed in the presentation.

Zhu, Shen↗
NASA NTRSDate not supplied

The “Gravity” of Combustion, Fluid and Soft Matter Research

Over the next year, the National Academies of Science, Engineering and Medicine (NASEM) will be developing the report for the next Decadal Survey on Life and Physical Sciences Research in space 2023-2032. This document will be used by the Science Mission Directorate in the National Aeronautics and Space Administration (NASA) to provide the framework for the vision, priorities, and strategic plan and budget for NASA’s research efforts in the area of biological and physical sciences in space, especially with regards to effects of gravity or the lack thereof. Gravity can affect fluid motion, shapes interfacial boundaries, squeezes compressible volumes by their surroundings, and ultimately affects heat and mass transfer as well as chemical reactions. NASEM will be requesting input from the research community via white papers in order to generate a comprehensive vision and strategy for a decade of transformative science at the frontiers of science space. Note: Accompanying videos are included in this submission and are listed based on there corresponding slide. For viewing you will need to download each mp4 formatted video, total run time 4 mins 2 secs. w/ color/sound.

combustion↗
DOE OSTI2023

SAF Combustion & Soot Processes [Slides]

The atomization, mixing, combustion and emissions characteristics of aviation fuels were measured using a novel approach based on a non-continuous injection scheme called the single-hole atomizer (SHA). High-speed microscopy revealed differences between fuels in terms of evaporation and mixing regimes over conditions relevant to modern and next generation aero-engine combustors. Measurements of liquid and vapor penetration, mixing fields, combustion and emissions metrics (ignition delay, lift-off length, PAH formation, soot mass) highlighted the effects of fuels and combustor conditions. The experimental results are being leveraged to adjust and validate chemical and CFD models. Detailed analysis of sampled soot showed subtle differences in soot morphology between fuels. The results revealed the presence of contaminants potentially affecting surface chemistry and the nucleation propensity of water droplets on particles. Chemical mechanisms for NJFCP A-2, C-1 and C-4 showed good performance over a large parameter space. Spray breakup at relight conditions is vastly different from the atomization observed at high pressure. CFD simulations of the SHA target conditions confirmed the good behavior of the C-1 kinetic mechanism. The simulations support the strong relationship between low and high temperature reactions. New altitude chamber facility to enable detailed characterization of the heterogeneous nucleation process of water on aerosol particles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1996

Lubricous Deposit Formed In Situ Between Wearing Surfaces at High Temperatures

Many components of future aircraft will be constructed from novel high-temperature materials, such as superalloys and ceramic composites, to meet expected operating temperatures in excess of 300 C. There are no known liquid lubricants that can lubricate above 300 C without significant decomposition. Solid lubricants could be considered, but problems caused by the higher friction coefficients and wear rates of the solid lubricant film make this an undesirable approach. An alternative method of lubrication is currently being investigated: vapor phase lubrication. In vapor phase lubrication, an organic liquid (in our studies a thioether was used) is vaporized into a flowing air stream that is directed to sliding surfaces where lubrication is needed. The organic vapor reacts at the concentrated contact sliding area generating a lubricous deposit. This deposit has been characterized as a thin polymeric film that can provide effective lubrication at temperatures greater than 400 C. Initial tribological studies were conducted at the NASA Lewis Research Center and Cleveland State University with a high-temperature friction and wear tribometer. A cast iron rod was loaded (a 4-kg mass was used to generate a contact pressure of 1.2 MPa) against a reciprocating, cast iron plate at 500 C. This system was then lubricated with the vapor phase of thioether.

Source record↗
NASA NTRS2008

SIM-Lite Update

Discussion focus on: SIM-Lite Instrument Update - 6m baseline, 50cm, approximately 900M cost; Technology Update - Systematic errors and floor; SIM-Lite terrestrial planet discovery capability; Double blind multiple planet study summary; and the changing landscape of exoplanet science and the role of SIM-Lite. Slides include technology to flight component engineering; instrumental systematic errors; ultra deep search for Earth clones; double blind test, astrometric detection of Earths in multiplanet systems; the current era of exoplanet science and where SIM-Lite fits in; the next frontier and where SIM-Lite fits in, why SIM is unique in discovering Earths; imaging planet status is uncertain without masses and ages; SIM role in establishing how planetary systems form and evolve; and SIM probes of broad planet mass range around young stars.

exoplanets↗
DOE OSTI2020

Tribochemical changes of alloy 800HT under sliding contact at elevated temperature in impure helium environment

This work investigates the chemical changes of the surface of Alloy 800HT during sliding contact under helium atmosphere in the presence of impurities at 750 °C, which is of interest for the nuclear industry. The alloy samples are exposed to helium (He) atmosphere at high temperature for long duration of 500 h to identify the chemical and topographical changes of the alloy surface. The oxidation rate constant is reported based on the weight change data. For the tribo-experimental samples, the surfaces inside and outside the wear track are studied thoroughly using techniques such as secondary electron microscopy, energy dispersive spectroscopy, x-ray diffraction, Raman spectroscopy and secondary ion mass spectroscopy. The formation and evolution of surface oxides are discussed in He atmosphere, compared with air. The presence of Fe-rich thin layer of oxide on top of a thicker Cr-rich oxide and a mixed spinel-based inner layer on the bulk is found. The persistent presence of thicker Fe3O4 in the wear track in high temperature air proved to be the reason of lower friction property. Pre-oxidation of the samples in air or He does not improve but worsen the tribological behavior in He atmosphere.

36 MATERIALS SCIENCE↗
NASA NTRS2009

Measurement of Trap Length for an Optical Trap

The trap length along the beam axis for an optical trap formed with an upright, oil-immersion microscope was measured. The goals for this effort were twofold. It was deemed useful to understand the depth to which an optical trap can reach for purposes of developing a tool to assist in the fabrication of miniature devices. Additionally, it was desired to know whether the measured trap length favored one or the other of two competing theories to model an optical trap. The approach was to trap a microsphere of known size and mass and raise it from its initial trap position. The microsphere was then dropped by blocking the laser beam for a pre-determined amount of time. Dropping the microsphere in a free-fall mode from various heights relative to the coverslip provides an estimate of how the trapping length changes with depth in water in a sample chamber on a microscope slide. While it was not possible to measure the trap length with sufficient precision to support any particular theory of optical trap formation, it was possible to find regions where the presence of physical boundaries influenced optical traps, and determine that the trap length, for the apparatus studied, is between 6 and 7 m. These results allow more precise control using optical micromanipulation to assemble miniature devices by providing information about the distance over which an optical trap is effective.

Wrbanek, Susan Y.↗
DOE OSTI2020

Gaussian Process Optimization of Sensitivity-Based Similarity Metrics between New Nuclear Applications and New/Existing Benchmarks [Slides]

This presentation discusses Nuclear Criticality Safety (NCS) and how designing safe, new nuclear criticality experiments requires expert judgement, which could take years of experience. Sensitivity/uncertainty (S/U) analysis can be utilized by less experienced individuals to conservatively estimate uncertainties in important parameters, such as k eff , in newly proposed nuclear experiments. The presentation poses the question of how this analysis can be performed and states that the answer lies in matching new nuclear experiments with existing benchmark experiments using similarity metrics. By increasing the criticality safety of the application in this work, higher mass limits could be used in PF-4 operations. Additionally, the presentation discusses MCNP6.2®, Whisper-1.1, the software that can be used in this analysis. Also discussed is the fact that International Criticality Safety Benchmark Evaluation Project (ICSBEP) benchmarks rarely match new nuclear applications and that there are significant differences in given set of materials and/or geometry. If there are no benchmarks that match the application, the presentation discusses the possibility of creating new benchmarks. In conclusion, this work presents a Gaussian process (GP) optimization scheme that was used to generate new benchmarks with the highest sensitivity-based similarity metrics to user-defined nuclear applications. The Gaussian process optimization successfully designed 3 new experimental benchmarks that were highly correlated to the application of interest and had k eff values near critical. Optimization over c k,i-r has shown that investigating specific isotope reactions for different applications is crucial to designing benchmark experiments. Partial contribution from Pu dominates c k similarity metric. Future work includes testing new stand-alone similarity metrics or new combinations of similarity metrics as the design criterion of this optimization – design criterion is application dependent.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2003

Spacecraft Design Thermal Control Subsystem

This slide presentation reviews the functions of the thermal control subsystem engineers in the design of spacecraft. The goal of the thermal control subsystem that will be used in a spacecraft is to maintain the temperature of all spacecraft components, subsystems, and all the flight systems within specified limits for all flight modes from launch to the end of the mission. For most thermal control subsystems the mass, power and control and sensing systems must be kept below 10% of the total flight system resources. This means that the thermal control engineer is involved in all other flight systems designs. The two concepts of thermal control, passive and active are reviewed and the use of thermal modeling tools are explained. The testing of the thermal control is also reviewed.

thermal control↗
DOE OSTI2024

Pretest Modeling A Spent Nuclear Fuel Seismic Shake Test

The U.S. Department of Energy Spent Fuel and Waste Science and Technology (SFWST) program is planning to conduct a series of full-scale shake table tests to simulate hypothetical earthquake conditions and record the response of surrogate spent nuclear fuel (SNF) assemblies in a dry canister storage system mockup. The shake table motions will represent a range of hypothetical earthquake conditions at hypothetical locations in the continental U.S. to generally define the range of mechanical loads that SNF can be expected to experience during extended dry storage periods. This paper describes the pretest predictions made with LS-DYNA models of the mockup storage systems. The test will use two dry storage system configurations, a mockup vertical concrete cask (VCC) and a mockup horizontal storage module (HSM). The test will use a production-quality canister and basket. Within the canister will be four instrumented fuel assemblies with fuel rods containing surrogate mass and 28 instrumented dummy assemblies that are intended to match the mass and outer dimension of a fuel assembly. The finite element models include models of the VCC and HSM on the shake table to calculate the system level dynamic responses and separate single fuel assembly models to calculate stress and strain in fuel assembly components. Both types of models include nonlinear behavior like rod-to-rod contact and the ability for VCC’s to rock and slide. This paper presents the expected response of the VCC, HSM, and fuel assemblies to the shake table testing that is planned to start in April of 2024. The earthquake conditions represent seismic hazards in the 2,000-to-20,000-year return period range. The test data is expected to confirm the expectation that fuel rod cladding will remain intact, fuel assembly structural components like guide tubes will remain intact, and no significant VCC sliding or tipping will occur in the range of conditions to be tested with the shake table.

Klymyshyn, Nicholas A.↗
DOE OSTI2023

Simulation of Molecular Hydrogen Jets and Visualization of Associated Hydrodynamic Features [Slides]

A numerical method is presented for solving the Navier-Stokes equations to represent a steady-state hydrogen jet expanding into a vacuum chamber. This numerical method has been evaluated using three test problems with promising results. Simulations of the hydrogen jet indicate the presence of a low temperature region (less than 15 K) within the jet for the high flow rate case. The high flow rate case also gives rise to a large recirculation region within the jet. The conditions at the minimum temperature point within the jet approach the hydrogen sublimation line when the mass flow rate exceeds 2 g/s, which may allow for the formation of hydrogen ice crystals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2008

The Formation of Filament Threads in a Sheared Magnetic Field

This slide presentation reviews the mechanism that form the filament threads in the sheared magnetic field of the solar photosphere. There are observations of the filaments, a chart showing the magnetic field configuration for the filaments, and charts that show the thermal instability, and thermal conduction. Discussion of the question "How is it possible for a magnetic field to inhibit heat flow in a coronal plasma without simultaneously restricting the mass flow required for the growth of density condensations?" is reviewed. Equations that are used in the model are given. The characteristics of dynamic condensations are reviewed. There are charts that show the density perturbations for principal dynamic condensation mode and 1st harmonic. The characteristics of the kinematic condensations are also discussed. The types of perturbations that were studied are: (1) Generic perturbation with T(sub 0) < T(sub c) (2) Generic perturbation with T(sub 0) = T(sub c) (3) Random perturbation with T(sub 0)< T(sub c).

condensational instability↗
NASA NTRS1990

Lidar and aircraft studies of deep Cirrus systems from the 1986 FIRE IFO

Several NCAR King Air flight missions were conducted during the Wisconsin FIRE IFO experiment in support of the University of Utah polarization lidar observations of deep cirrus cloud systems at the Wausau ground site. Data collected from four cirrus systems are included in this analysis, including those of 22 and 28 October, and 1 and 2 November. Lidar data were generally obtained at 2 min intervals in the zenith direction over observation periods that ranged from approximately 4 to 10 h, bracketing the aircraft missions. The data were processed to yield height-time (HTI) displays of lidar linear depolarization ratio sigma and relative range-normalized return power P. King Air operations consisted of a combination of rapid profiling and Lagrangian spiral descents and stacked racetrack patterns in the vicinity of the field site. From the spiral descents are constructed vertical profiles of ice particle concentration N(sub i) and ice mass content IWC derived from PMS 2-D probe imagery and, when detected, FSSP cloud droplet concentration N(sub W) and liquid water content, LWC. Aircraft flight leg data are presented for the vertical velocity W and the same ice and water cloud content parameters. In addition, aerosol particle concentrations obtained with the ASAS probe are examined, and photographs of ice particles collected in-situ on oil-coated slides are presented to illustrate ice particle habit.

Sassen, Kenneth↗
NASA NTRS2010

X-Ray Optics for the 2020's

X-ray optics is an essential and enabling technology for x-ray astronomy. This slide presentation presents the authors views on the requirements for x-ray optics as progress is made toward building IXO and preparing for the 2020's. The presentation reviews the status of several technologies that are being developed and outlines the steps that we as a community needs to take to move toward x-ray optics meeting the five key requirements: (1) high angular resolution, (2) large effective area, (3) low mass, (4) fast production, and (5) low cost. There is discussion of segmentation vs full shell, size of the mirror segment, mirror segment frabrication, post-slumping figure improvement, and characterization of coating quality.

Zhang, Will↗