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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Nickel-hydrogen LEO cycling at 20 percent - 50 percent DOD

The test setup consists of four major elements: the programmable power supplies and load banks, the data acquisition and control system control computer, and the NiH2 specimen test cells. A simplified block diagram of the test setup is shown. The test setup provides complete battery isolation should a fault occur, and fusing as necessary to protect the battery cells and other equipment. Front panel switches provide for power supply configuration and battery isolation. Front panel meters provide continuous real-time visual monitoring of the voltage and current for each pack of cells. A strip chart recorder provides a hard copy of the voltage and current profiles for each of the packs. The test operates continuously with minimal human interface, except during special tests. The two power supplies are controlled by resistance programming. A bank of resistors and relays was built which can be switched by the control computer to provide control over the charge current to the batteries. The load banks are controlled by the 3497A. The 3497A is equipped with a 0.5 volt programmable power supply which is used to voltage program the load banks. A Hewlett-Packard Vectra 9000 running an HP Basic program is used as the control computer to remotely instruct the 3497A (data acquisition and control) to scan the data channels and retrieve test data. The program then reads, calculates, and stores the data. If an anomaly occurs, the program will disconnect the cells and shut down the test to avoid damage to the cells or equipment.

Lowery, John E.↗
NASA NTRS2005

Solid Hydrogen Experiments for Atomic Propellants: Particle Formation, Imaging, Observations, and Analyses

This report presents particle formation observations and detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium. Hydrogen was frozen into particles in liquid helium, and observed with a video camera. The solid hydrogen particle sizes and the total mass of hydrogen particles were estimated. These newly analyzed data are from the test series held on February 28, 2001. Particle sizes from previous testing in 1999 and the testing in 2001 were similar. Though the 2001 testing created similar particles sizes, many new particle formation phenomena were observed: microparticles and delayed particle formation. These experiment image analyses are some of the first steps toward visually characterizing these particles, and they allow designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

Palaszewski, Bryan↗
DOE OSTI2026

Background-Oriented Schlieren Velocimetry of Helium Coolant Flow in Additively Manufactured Channels

High-pressure helium gas cooling is an attractive solution for thermal management of the fusion blanket first wall, as this coolant is chemically and neutronically inert and separable from hydrogenic species. However, due to the low thermal mass of helium, geometric optimization of these channels is required to provide sufficient cooling at manageable flow rates and pumping burdens. Increasingly, analysis and optimization of these coolant channels rely on computational fluid dynamics (CFD) simulations, and these require relevant experimental data for turbulence model validation. Toward this end, a high-pressure helium gas flow visualization system has been employed to image the flow of helium in flow channels with one-sided heating, mimicking the blanket first wall environment. Flow of helium at 4 MPa pressure and flow rates up to 68 g/s (Reynolds number 57 000) is supplied to rectangular channel test sections, with uniform heating applied to the bottom wall of the channel at heat fluxes varied between roughly 50 and 130 kW/m2. A high-speed camera is used to image index of refraction (IOR) gradients in the fluid via background-oriented schlieren (BOS), and temperature and pressure instrumentation are used to characterize thermal-hydraulic performance of each channel. Cross correlation of time-resolved BOS images is then used to calculate time-averaged 2-D helium velocity fields. Flow in additively manufactured (AM) channels is examined in this manner, including both featureless channels and those containing baffling as a heat transfer enhancement. The flow distribution seen in the featureless case differs significantly from that seen in prior simulations, whereas the flow in the baffled case shows the predicted behavior of flow forced along the heated wall. This augmented flow distribution is seen to increase the heat transfer coefficient in the baffled test section. Here, strategies are discussed for ongoing and future validation of these simulations, with the aim of model deployment for blanket cooling design and optimization.

Additive manufacturing↗
NASA NTRS1990

Transpiration cooling in the locality of a transverse fuel jet for supersonic combustors

The objective of the current work was to determine the feasibility of transpiration cooling for the relief of the local heating rates in the region of a sonic, perpendicular, fuel jet of gaseous hydrogen. Experiments were conducted to determine the interaction between the cooling required and flameholding limits of a transverse jet in a high-enthalpy, Mach 3 flow in both open-jet and direct-connect test mode. Pulsed shadowgraphs were used to illustrate the flow field. Infrared thermal images indicated the surface temperatures, and the OH(-) emission of the flame was used to visualize the limits of combustion. Wall, static presures indicated the location of the combustion within the duct and were used to calculate the combustion efficiency. The results from both series of tests at facility total temperatures of 1700 K and 2000 K are presented.

Northam, G. Burton↗
DOE OSTI2023

Silver nanoparticle enhanced metal-organic matrix with interface-engineering for efficient photocatalytic hydrogen evolution

Integrating plasmonic nanoparticles into the photoactive metal-organic matrix is highly desirable due to the plasmonic near field enhancement, complementary light absorption, and accelerated separation of photogenerated charge carriers at the junction interface. The construction of a well-defined, intimate interface is vital for efficient charge carrier separation, however, it remains a challenge in synthesis. Here we synthesize a junction bearing intimate interface, composed of plasmonic Ag nanoparticles and matrix with silver node via a facile one-step approach. The plasmonic effect of Ag nanoparticles on the matrix is visualized through electron energy loss mapping. Moreover, charge carrier transfer from the plasmonic nanoparticles to the matrix is verified through ultrafast transient absorption spectroscopy and in-situ photoelectron spectroscopy. The system delivers highly efficient visible-light photocatalytic H 2 generation, surpassing most reported metal-organic framework-based photocatalytic systems. This work sheds light on effective electronic and energy bridging between plasmonic nanoparticles and organic semiconductors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1983

On the origin of the 6.1-ms pulsar

A quantitative model is presented to account for the observed features of the binary pulsar PSR1953+53. A lower giant branch star is suggested to have evolved on a nuclear time scale while orbiting a neutron star, with mass transfer to the neutron star commencing when the giant attained its Roche lobe. A radius-core mass relationship was used to examined the processes that occurred after the hydrogen atmosphere was drained off to the neutron star. Tidal dissipation has circularized the orbit of the companion during mass transfer, while the orbit expanded. Accretion torques caused spin-up of the neutron star, which had a magnetic moment of no more than 3 x 10 to the 27th G/cu cm. The drained star became a degenerate dwarf with very faint luminosity, which accounts for no visual companion having been observed to date.

Joss, P. C.↗
NASA NTRS1997

The Definition Study for Implementation of the IMAP Mission

The Small Explorer Mission in intended to provide the first global visualization of Earth's inner magnetosphere. IMAP promises to greatly advance our knowledge of the global distributions and dynamics of near-Earth radiation environment by obtaining first simultaneous images of the plasmasphere at extreme ultraviolet wavelengths, of the extraterrestrial ring current and the earthward portions of the plasma sheet as seen in their emissions of neutral atoms from charge exchange of plasma hot ions with geocoronal hydrogen atoms, and of the aurora in its far-ultraviolet emissions.

Frank, L. A.↗
NASA NTRS1999

Effects of Buoyancy in Hydrogen Jet Diffusion Flames

This project was carried out to understand the effects of heat release and buoyancy on the flame structure of diffusion flames. Experiments were conducted at atmospheric pressure in both normal gravity and microgravity conditions in the NASA LeRC 2.2 s drop tower. Experiments were also conducted in a variable pressure combustion facility in normal gravity to scale buoyancy and thus, to supplement the drop tower experiments. Pure H2 or H2 mixed with He was used as the jet fluid to avoid the complexities associated with soot formation. Fuel jet burning in quiescent air was visualized and quantified by the Rainbow Schlieren Deflectometry (RSD) to obtain scalar profiles (temperature, oxygen concentration) within the flame. Burner tube diameter (d) was varied from 0.3 to 1.19 mm producing jet exit Reynolds numbers ranging from 40 to 1900, and generating flames encompassing laminar and transitional (laminar to turbulent) flow structure. Some experiments were also complemented with the CFD analysis. In a previous paper, we have presented details of the RSD technique, comparison of computed and measured scalar distributions, and effects of buoyancy on laminar and transitional H2 gas-jet diffusion flames. Results obtained from the RSD technique, variable pressure combustion chamber, and theoretical models have been published. Subsequently, we have developed a new drop rig with improved optical and image acquisition. In this set up, the schlieren images are acquired in real time and stored digitally in RAM of an onboard computer. This paper deals with laminar diffusion flames of pure H2 in normal and microgravity.

Agrawal, A. K.↗
NASA NTRS2006

Safe Use of Hydrogen and Hydrogen Systems

This is a viewgraph presentation that is a course for teaching the safe use of hydrogen. The objectives of the course are 1. To familiarize the student with H2 safety properties 2. To enable the identification, evaluations and addressing of H2 system hazards 3. To teach: a. Safe practices for, b. Design, c. Materials selection, d. H2 system operation, e. Physical principles and empirical observations on which these safe practices are based, f. How to respond to emergency situations involving H2, g How to visualize safety concepts through in-class exercises, h. Identify numerous parameters important to H2 safety.

Maes, Miguel↗
NASA NTRS1989

KOH concentration effect on the cycle life of nickel-hydrogen cells. Part 4: Results of failure analyses

KOH concentration effects on cycle life of a Ni/H2 cell have been studied by carrying out a cycle life test of ten Ni/H2 boiler plate cells which contain electrolytes of various KOH concentrations. Failure analyses of these cells were carried out after completion of the life test which accumulated up to 40,000 cycles at an 80 percent depth of discharge over a period of 3.7 years. These failure analyses included studies on changes of electrical characteristics of test cells and component analyses after disassembly of the cell. The component analyses included visual inspections, dimensional changes, capacity measurements of nickel electrodes, scanning electron microscopy, BET surface area measurements, and chemical analyses. Results have indicated that failure mode and change in the nickel electrode varied as the concentration was varied, especially, when the concentration was changed from 31 percent or higher to 26 percent or lower.

Lim, H. S.↗
NASA NTRS1990

KOH concentration effect on the cycle life of nickel-hydrogen cells. IV - Results of failure analysis

Potassium hydroxide concentration effects on the cycle life of a Ni/H2 cell have been studied by carrying out a cycle life test on ten Ni/H2 boiler plate cells which contain electrolytes of various KOH concentrations. Failure analyses of these cells were carried out after completion of the life test, which accumulated up to 40,000 cycles at an 80-percent depth of discharge over a period of 3.7 years. These failure analyses included studies on changes of electrical characteristics of test cells, and component analyses after disassembly of the cell. The component analyses included visual inspections, dimensional changes, capacity measurements of nickel electrodes, scanning electron microscopy, surface area measurements, and chemical analyses. Results have indicated that failure mode and change in the nickel electrode varied as the concentration was varied, especially when the concentration was changed from 31 percent or higher to 26 percent or lower.

Lim, H. S.↗
NASA NTRS1993

A Unique Photon Bombardment System for Space Applications

The innovative Electromagnetic Radiation Collection and Concentration System (EMRCCS) described is the foundation for the development of a multiplicity of space and terrestrial system formats. The system capability allows its use in the visual, infrared, and ultraviolet ranges of the spectrum for EM collection, concentration, source/receptor tracking, and targeting. The nonimaging modular optical system uses a physically static position aperture for EM radiation collection. Folded optics provide the concentration of the radiation and source autotracking. The collected and concentrated electromagnetic radiation is utilized in many applications, e.g., solar spectrum in thermal and associative photon bombardment applications for hazardous waste management, water purification, metal hardening, hydrogen generation, photovoltaics, etc., in both space and terrestrial segment utilization. Additionally, at the high end of the concentration capability range, i.e., 60,000+, a solar-pulsed laser system is possible.

Klein, E. J.↗
NASA NTRS1979

Measurements of the extinction to the molecular hydrogen emission from the Orion Nebula

Observations of the reddening of two pairs of H2 emission lines in the Orion Nebula are presented. A reddening of 0.8 + or - 0.2 mag between 2.12 and 2.42 microns is derived from observations of the intensity ratio of the v = 1-0 S(1) (2.12-micron) line and the Q(3) (2.42-micron) line and a comparison of this ratio with its unreddened value. The result is checked by a measurement of the intensity ratio of the v = 1-0 S(2) (2.03-micron) line and the Q(4) (2.43-micron) line. The total IR and visual extinctions to the emission region are inferred to be 4 + or - 1 mag (2.1 microns) and 40 + or - 10 mag (visual). Previous measurements of the H2 emission lines in Orion are corrected on the basis of these results, yielding a total H2 luminosity of approximately 2000 suns, an average column density of about 3 x 10 to the 20th per sq cm, and essentially equal rotational and vibrational temperatures (2000 K) for the H2. It is concluded that the H2 emission region in Orion lies within the molecular cloud, probably at the same depth as the IR cluster.

Beckwith, S.↗
DOE OSTI2023

Novel gas exposure system for the controlled exposure of plants to gaseous hydrogen fluoride

Abstract Plants can serve as sensitive bioindicators of the presence of contaminant vapors in the atmosphere. This work describes a novel laboratory-based gas exposure system capable of calibrating plants as bioindicators for the detection and delineation of the atmospheric contaminant hydrogen fluoride (HF) as a preparatory step for monitoring release emissions. To evaluate changes in plant phenotype and stress-induced physiological effects attributed to HF alone, the gas exposure chamber must have additional controls to simulate otherwise optimal plant growth conditions including variables such as light intensity, photoperiod, temperature, and irrigation. The exposure system was designed to maintain constant growth conditions during a series of independent experiments that varied between optimal (control) and stressful (HF exposure) conditions. The system was also designed to ensure the safe handling and application of HF. An initial system calibration introduced HF gas into the exposure chamber and monitored HF concentrations by cavity ring-down spectroscopy for a 48-h period. Stable concentrations inside the exposure chamber were observed after approximately 15 h, and losses of HF to the system ranged from 88 to 91%. A model plant species ( Festuca arundinacea ) was then exposed to HF for 48 h. Visual phenotype stress-induced responses aligned with symptoms reported in the literature for fluoride exposure (tip dieback and discoloration along the dieback transition margin). Fluoride concentrations in exposed tissues compared to control tissues confirmed enhanced fluoride uptake due to HF exposure. The system described herein can be applied to other reactive atmospheric pollutants of interest in support of bioindicator research.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1983

A comparison of high resolution optical and radio observations of W3

High resolution maps of the W3 complex for radio continuum and selected optical emission lines are used to derive the visual extinction A(V), the excitation, and the evolutionary state of the component H II regions. A large diffuse H II region in the east, which is the most highly evolved of this type, is found, together with a southern complex of H II regions and a northern complex of young and compact H II regions still embedded in the W3 molecular core. A comparison of the observed dust distribution with ionized and atomic hydrogen and several other molecules in W3 shows the functional relationship between the C-130 column density and A(V) to be in accord with Strohacker's (1978) result for dark clouds.

Dickel, H. R.↗
DOE OSTI2024

Direct evidence from STXM analysis of enhanced oxygen storage capacity in ceria through the addition of Cu and Mg: Correlation of HT-WGS reaction performance

Here, scanning transmission X-ray microscopy (STXM) analysis was utilized to directly present visual evidence of changes in oxygen storage capacity (OSC) when small amounts of an additive were incorporated into CeO2. Specifically, the chemical map measured by STXM analysis differentiated between Cu-rich and Ce-rich areas to derive the proportion of Ce3+. Additionally, we found that the dispersion of Cu significantly influenced the formation of OSC. The findings were applied to the high-temperature water–gas shift reaction for producing high-purity hydrogen from waste-derived syngas, establishing a correlation with catalyst performance. Consequently, the CCM75 (Ce/Mg = 75/25) catalyst demonstrated the highest Cu dispersion and OSC values (6.9 %, 800.3 μmolO/gcat), and it also showed the highest CO conversion (79 % at 450 °C) and stability (−7.7 % at 450 °C after 50 h), attributed to the significant presence of active Cu. This study confirms previously reported interactions between Cu and CeO2 and uncovers the significant roles of Cu and Mg in this catalysis system, providing new understanding of the mechanisms that facilitate OSC improvement.

Lee, Ru-Ri↗
NASA NTRS1987

Giant H II regions in M81

H-alpha and VLA radio continuum observations at wavelengths of 6 and 20 cm are used to study the distribution of extinction and the distribution of giant radio H II regions along the spiral arms in M81. The radial distribution of visual extinction Av in the plane of M81 shows no trend, with an upper limit 0.1 mag/kpc for the radial extinction gradient and a mean Av of 1.1 + or - 0.4 mag. Nearly all the giant radio H II regions lie along the spiral arms or the inner H I ring. The radial distribution of the set of giant radio H II regions exhibits a strong maximum at a galactocentric distance R roughly 300 arcsec. Unless molecular hydrogen in M81 is also concentrated near R roughly 300 arcsec, the data disagree with Visser's (1980) model for star formation associated with a density wave. Some suggestions are made about how to change the ballistic particle model of Leisawitz and Bash to agree with the observed radial distribution of giant radio H II regions.

Kaufman, Michele↗
NASA NTRS1986

Mixing of cryogenic fluids and predicted detonation properties for multiphase liquid oxygen and liquid hydrogen

The mixing and explosion of LOX and LH sub 2 is a concern for Space Transportation System operations. To understand this problem, cryogenic mixing is experimentally studied by pouring 1,2,2 trichloro 2,1,1 trifluoroethane (Freon 113) into LN sub 2, LN sub 2 into LH sub 2, and LH sub 2 into into LN sub 2 in a 1 m by 15 cm cylindrical glass vessel. Data from these experiments is compared with previous studies and a hypothesis is advanced that LOX/LH sub 2 mixing will result in a complex, heterogenous, multiphase aggregation including LOX, SOX, LH sub 2, and VH sub 2 using the multiphase hypothesis. Visual and x ray observations of the process and mass measurements are reported.

Bishop, C. V.↗