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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

The objectives are to measure laboratory rate coefficients for key reactions of hydrocarbon molecules and radicals at low temperatures, which are relevant to the atmospheric photochemistry of Saturn, Jupiter, and Titan. Upcoming NASA planetary missions, such as Cassini, will probe the atmosphere of Titan in more detail, offering an excellent opportunity to test kinetic models and to establish fiducial standards for using kinetic models to interpret various parameters of the outer planets. Accurate low temperature kinetic data, which are presently lacking, may require crucial revisions to the rates of formation and destruction and are of utmost importance to the success of these efforts. In this program, several key reactions of ethynyl radicals (C2H) with acetylene (C2H2), methane (CH4), and oxygen (O2), down to temperatures of 170 K were successfully investigated. The experimental apparatus developed in our laboratory for measuring reaction kinetics at low temperatures consists of a laser photolysis/infrared probe laser setup. The rate measurements are carried out as a function of (low) temperature with a transverse flow cell designed specifically for these studies. A 193 nm argon fluoride pulsed excimer laser is used to photolyze a suitable precursor molecule, such as acetylene to produce C2H, and a high resolution, tunable infrared F-center laser (2.3-3.35 mu m) probes the transient concentrations of the radical species directly in absorption to extract the kinetic rate coefficients.

Leone, Stephen R.↗
NASA NTRS2005

Morphological Evolution of Directional Solidification Interfaces in Microgravity: An Analysis of Model Experiments Performed on the International Space Station

A series of experiments performed using the Pore Formation and Mobility Investigation (PFMI) apparatus within the glovebox facility (GBX) on board the International Space Station (ISS) has provided video images of the morphological evolution of a three-dimensional interface in a diffusion controlled regime. The experimental samples were prepared on ground by filling glass tubes, 1 cm ID and approximately 30 cm in length, with "alloys" of succinonitrile (SCN) and water in an atmosphere of nitrogen at 450 millibar pressure. The compositions of the samples processed and analyzed are 0.25,0.5 and 1.0 wt% water. Experimental processing parameters of temperature gradient and translation speed, as well as camera settings, were remotely monitored and manipulated from the ground Telescience Center (TSC) at the Marshall !3pace Flight Center. During the experiments, the sample was first subjected to a unidirectional melt back, generally at 10 microns per second, with a constant temperature gradient ahead of the melting interface. Following the melt back, the interface was allowed to stabilize before translation is initiated. The temperatures in the sample were monitored by six in situ thermocouples and the position is monitored by an optical linear encoder. For the experiments performed and analyzed, the gradients ranged from 2.5 - 3.3 K/mm and the initial pulling velocities ranged from 0.7 micron per second to 1 micron per second with subsequent transition velocities of up to 100 microns per second. The data provided by the PFMI for analysis includes near-real-time (NRT) video captured on the ground during the experiment runs, ISS Video Tape Recorder (VTR) data dumped from the VTR at the end of the experiment run and recorded on the ground, telemetry data including temperature and position measurements, and limited flight HI-8 tapes in 2 camera views of experiment runs for which tapes have been returned to the investigators from ISS. Because of limited down mass from the ISS, the majority of the initial analysis has been performed using the NRT and VTR video data but will be supplemented with the HI-8 video as it becomes available. hardware and procedures required to prepare samples for correlation to flight samples is described. Using this ground-based system, a series of experiments have been performed for direct comparison with the flight data. The results of these comparisons as well as implications to future microgravity experiments are presented and discussed. A ground-based thin-sample directional solidification system as well as all associated

Strutzenberg, Louise L.↗
NASA NTRS1988

A predictive monsoon signal in the surface level thermal field over India

The mean monthly surface thermal field over India during the premonsoon months March-May, based on mean monthly-temperature/minimum-temperature/maximum-temperature data from the network of 119 stations, was examined with the objective of locating significant predictor parameters for forecasting Indian monsoon rainfall. The results of linear correlation analysis bring out three areas for which the relationships between Indian monsoon rainfalls and the area average of mean monthly minimum temperature for April or for May were found to be significant. The best correlation was found for the southern peninsular area, where the mean May minimum temperature is significantly related to the 500 mB April ridge, a tendency in the Southern Oscillation Index, and a tendency in eastern equatorial Pacific SST.

Mooley, D. A.↗
NASA NTRS1994

A search for relativistic electron induced stratospheric ozone depletion

Possible ozone changes at 1 mb associated with the time variation and precipitation of relativistic electrons are investigated by examining the NIMBUS 7 SBUV ozone data set and corresponding temperatures derived from NMC data. No ozone depletion was observed in high-latitude summer when temperature fluctuations are small. In winter more variation in ozone occurs, but large temperature changes make it difficult to identify specific ozone decreases as being the result of relativistic electron precipitation.

Aikin, Arthur C.↗
DOE OSTI2024

Utah FORGE: Neubrex Well 16B(78)-32 Fiber Optics Reports - Stimulation and Circulation, 2024

This zip file contains reports discussing the use of fiber optics during well 16B(78)-32 stimulation and circulation tests in the summer of 2024. The reports cover the collection of strain rate and temperature change data during these well events. Theory, methods, and initial data visualizations are included in the reports, highlighting the value of these data types.

15 GEOTHERMAL ENERGY↗
NASA NTRS1984

Airborne measurements of launch vehicle effluent of STS-2 launch on November 12, 1981 at Cape Canaveral, Florida

The second Space Shuttle (STS-2) was launched from the John F. Kennedy Space Center at 1010 EST on November 12, 1981. An instrumented light airplane was used to measure the emitted concentration of Shuttle exhaust products produced during launch. The airplane accomplished 31 passes through and under the exhaust cloud in the 1 hr 45 min immediately following the launch. Measurements included the following: (1) particulate data in the form of a light scattering coefficient obtained from an integrating nephelometer, (2) particulate concentrations and mass concentrations obtained from a spectrometer probe, (3) gaseous HCl and total HCl concentrations obtained from a gas-filter-correlation instrument and a chemiluminescent instrument, respectively, and (4) outside-air temperature and dew-point temperature. These data are presented along with time, altitude, and position for each cloud pass. These data are within the range of values observed during similar measurements made during the first Space Shuttle launch on April 12, 1981.

Maddrea, G. L., Jr.↗
NASA NTRS2000

Development and Application of Tools to Characterize the Oxidative Degradation of AP/HTPB/Al Propellants in a Propellant Reliability Study

The oxidative thermal aging of a crosslinked hydroxyl-terminated polybutadiene (HTPB)/isophorone diisocyanate (IPDI) polyurethane rubber was studied at temperatures between 25 C and 125 C. Changes in tensile elongation, mechanical hardening, polymer network properties, density, O2 permeation, and molecular chain dynamics were investigated as a function of age. The techniques used include solvent swelling, detailed modulus profiling, and NMR relaxation measurements. The Arrhenius methodology, which normally assumes a linear extrapolation of high temperature aging data, is critically evaluated by using extensive data superposition and highly sensitive oxygen consumption measurements. Significant curvature in the Arrhenius diagram of these oxidation rates is observed to be similar to previous results found for other rubber materials that have been evaluated by this technique. Preliminary gel/network properties suggest that crosslinking is the dominant process at higher temperatures. The effect on the oxidation rate of the binder when other constituents found in propellants are present, such as ammonium perchlorate, plasticizer and aluminum powder, is presented.

Celina, Mathew↗
NASA NTRS1989

Hot isostatic pressing of silicon nitride with boron nitride, boron carbide, and carbon additions

Si3N4 test bars containing additions of BN, B4C, and C, were hot isostatically pressed in Ta cladding at 1900 and 2050 C to 98.9 percent to 99.5 percent theoretical density. Room-temperature strength data on specimens containing 2 wt pct BN and 0.5 wt pct C were comparable to data obtained for Si3N4 sintered with Y2O3, Y2O3 and Al2O3, or ZrO2. The 1370 C strengths were less than those obtained for additions of Y2O3 or ZrO2 but greater than those obtained from a combination of Y2O3 and Al2O3. SEM fractography indicated that, as with other types of Si3N4, room-temperature strength was controlled by processing flaws. The decrease in strength at 1370 C was typical of Si3N4 having an amorphous grain-boundary phase. The primary advantage of nonoxide additions appears to be in facilitating specimen removal from the Ta cladding.

Mieskowski, Diane M.↗
NASA NTRS2010

Study of Fabry-Perot Etalon Stability and Tuning for Spectroscopic Rayleigh Scattering

The Fabry-Perot interferometer is a commonly employed instrument for resolving the spectrum of molecular Rayleigh scattered light for the purpose of evaluating flow properties such as gas velocity and temperature. Rayleigh scattered light from a focused laser beam can be directly imaged through a solid Fabry-Perot etalon onto a CCD detector to provide the spectral content of the scattered light. The spatial resolution of the measurements is governed by the locations of interference fringes. The location of the fringes can be changed by altering the etalon?s physical characteristics, such as thickness and index of refraction. For a fused silica solid etalon the physical properties can be adjusted by changing the etalon temperature; hence changing the order of the interference pattern and the physical fringe locations. Controlling the temperature of the etalon can provide for a slow time-response spatial scanning method for this type of etalon system. A custom designed liquid crystal Fabry-Perot (LCFP) can provide for a fast time-response method of scanning the etalon system. Voltage applied to the liquid crystal interface sets the etalon?s properties allowing Rayleigh measurements to be acquired at varying spatial locations across the image of the laser beam over a very short time period. A standard fused silica etalon and a tunable LCFP etalon are characterized to select the system that is best suited for Rayleigh scattering measurements in subsonic and supersonic flow regimes. A frequency-stabilized laser is used to investigate the apparent frequency stability and temperature sensitivity of the etalon systems. Frequency stability and temperature sensitivity data of the fused silica and LCFP etalon systems are presented in this paper, along with measurements of the LCFP etalon?s tuning capabilities. Rayleigh scattering velocity measurements with both etalon systems are presented, in an effort to determine which etalon is better suited to provide optical flow measurements of velocity, temperature, and density.

Clem, Michelle M.↗
NASA NTRS1994

(abstract) Odd Hydrogen in the Atmospheres of Earth and Mars

The Martian atmosphere has many features in common with the terrestrial mesosphere. Both share similar pressure and temperature ranges, and much of the same chemistry operates in each. For example, the radical species H, OH, and H(sub 2)O, which comprise the odd hydrogen family, are of central importance in the catalytic destruction of CO and O(sub 3) in both atmospheres. The inclusion of recent chemical kinetics data, specifically temperature dependent CO(sub 2) absorption cross-sections, into our one dimensional photochemical model of the Martial atmosphere shows that oxidation of CO by odd hydrogen is too efficient. The incorporation of smaller cross sections for CO(sub 2) leads to an enhanced photolysis rate of water vapor, increasing odd hydrogen to the point where the predicted mixing ratio of CO in our model is substantially less than the observed value of 6.5 x 10(sup -4). Interestingly, most photochemical models of the terrestrial mesosphere underestimate the CO and O(sub 3) densities using currently accepted photodissociation and kinetic rate coefficients. This has also been attributed to an overabundance of odd hydrogen in the models. We shall show that agreement between models and observations of CO in the Martian atmosphere as well as of CO and O(sub 3) in the terrestrial mesosphere can be achieved by revising the rate constants for the reactions OH + HO(sub 2) and CO + OH within their published uncertainties. The fact that similar revisions alleviate discrepancies in both the terrestrial and Martian atmospheres warrants a re-evaluation of these key rate constants at the appropriate temperatures and pressures.

dioxide ozone odd hydrogen family pressure tempera↗
NASA NTRS1997

PSP Testing at NASA Ames Research Center

Pressure sensitive paints (PSPs) are now used routinely for measuring surface pressures on wind tunnel models at transonic and supersonic Mach numbers. The method utilizes a surface coating containing fluorescent or phosphorescent materials, the brightness of which varies with the local air pressure on the surface. The present paper will summarize PSP activities (in progress and planned) at the NASA Ames Research Center. One of the main accomplishments at NASA Ames has been the development of a PSP measurement system that is production testing capable. This system has been integrated successfully into the large-scale wind tunnel facilities at Ames. There are several problems related to PSP testing which are unique to large-scale wind tunnel testing. The hardware is often difficult to set-up and must operate under harsh conditions (e.g. high pressures and low temperatures). The data acquisition and reduction times need to be kept to a minimum so that the overall wind tunnel productivity is not compromised. The pressure sensitive paints needs to be very robust; the paints must readily adhere to different surfaces with varying geometries and remain functional for long running times. The paint must have well understood, and preferably minimal, temperature sensitivity since fine control of the tunnel temperature is not easily achievable in the larger wind tunnels. In an effort to improve the overall accuracy of the PSP technique, we are currently evaluating some referenced pressure sensitive paints which contain a pressure- independent luminophor in addition to the one which is affected by the surface pressure. The two luminophors are chosen so that their emission wavelengths are somewhat different. Then by taking two 'wind-on' images with either two cameras (with different filters) or one camera with a rotating filter system, the need for 'wind-off' images can be eliminated. The ratio of the two wind-on images accounts for nonuniform lighting and model motion problems (physical movement of the model under aerodynamic loading) are not a concern any more. The paints and data acquisition and reduction software for this type of a PSI system are currently under development and evaluation. Additional information is contained within the original extended abstract.

Bell, J. H.↗
NASA NTRS1989

Evaluation of a strain-gage load calibration on a low-aspect-ratio wing structure at elevated temperature

The environmental aspect of elevated temperature and its relationship to the science of strain gage calibrations of aircraft structures are addressed. A section of a wing designed for a high-speed aircraft structure was used to study this problem. This structure was instrumented with strain gages calibrated at both elevated and room temperatures. Load equations derived from a high-temperature load calibration were compared with equations derived from an identical load calibration at room temperature. The implications of the high temperature load calibration were studied from the viewpoint of applicability and necessity. Load equations derived from the room temperature load calibration resulted in generally lower equation standard errors than equations derived from the elevated temperature load calibration. A distributed load was applied to the structure at elevated temperature and strain gage outputs were measured. This applied load was then calculated using equations derived from both the room temperature and elevated temperature calibration data. It was found that no significant differences between the two equation systems existed in terms of computing this applied distributed load, as long as the thermal shifts resulting from thermal stresses could be identified. This identification requires a heating of the structure. Therefore, it is concluded that for this structure, a high temperature load calibration is not required. However, a heating of the structure is required to determine thermal shifts.

Reardon, Lawrence F.↗
NASA NTRS2005

An Oil-Free Thrust Foil Bearing Facility Design, Calibration, and Operation

New testing capabilities are needed in order to foster thrust foil air bearing technology development and aid its transition into future Oil-Free gas turbines. This paper describes a new test apparatus capable of testing thrust foil air bearings up to 100 mm in diameter at speeds to 80,000 rpm and temperatures to 650 C (1200 F). Measured parameters include bearing torque, load capacity, and bearing temperatures. This data will be used for design performance evaluations and for validation of foil bearing models. Preliminary test results demonstrate that the rig is capable of testing thrust foil air bearings under a wide range of conditions which are anticipated in future Oil-Free gas turbines. Torque as a function of speed and temperature corroborates results expected from rudimentary performance models. A number of bearings were intentionally failed with no resultant damage whatsoever to the test rig. Several test conditions (specific speeds and loads) revealed undesirable axial shaft vibrations which have been attributed to the magnetic bearing control system and are under study. Based upon these preliminary results, this test rig will be a valuable tool for thrust foil bearing research, parametric studies and technology development.

Bauman, Steve↗
NASA NTRS2011

Understanding Coronal Heating with Emission Measure Distributions

It is widely believed that the cross-field spatial scale of coronal heating is small, so that the fundamental plasma structures (loop strands) are spatially unresolved. We therefore must appeal to diagnostic techniques that are not strongly affected by spatial averaging. One valuable observable is the emission measure distribution, EM(T), which indicates how much material is present at each temperature. Using data from the Extreme-ultraviolet Imaging Spectrograph on the Hinode mission, we have determined emission measure distributions in the cores of two active regions. The distributions have power law slopes of approximately 2.4 coolward of the peak. We compare these slopes, as well as the amount of emission measure at very high temperature, with the predictions of a series of models. The models assume impulsive heating (nanoflares) in unresolved strands and take full account of non equilibrium ionization. A variety of nanoflare properties and initial conditions are considered. We also comment on the selection of spectral lines for upcoming missions like Solar Orbiter.

Klimchik, James A.↗
NASA NTRS2021

The Atacama Cosmology Telescope: Summary of DR4 and DR5 Data Products and Data Access

Two recent large data releases for the Atacama Cosmology Telescope (ACT), called DR4 and DR5, are available for public access. These data include temperature and polarization maps that cover nearly half the sky at arcminute resolution in three frequency bands; lensing maps and component-separated maps covering ∼2100 deg 2 of sky; derived power spectra and cosmological likelihoods; a catalog of over 4000 galaxy clusters; and supporting ancillary products including beam functions and masks. The data and products are described in a suite of ACT papers; here we provide a summary. In order to facilitate ease of access to these data, we present a set of Jupyter IPython notebooks developed to introduce users to DR4, DR5, and the tools needed to analyze these data. The data products (excluding simulations) and the set of notebooks are publicly available on the NASA Legacy Archive for Microwave Background Data Analysis; simulation products are available on the National Energy Research Scientific Computing Center.

Maya Mallaby-Kay↗
DOE OSTI2022

Development of a Data Platform for High-Temperature Gas-cooled Reactor (HTGR) Nuclear Energy University Program (NEUP) Thermal-Fluid Experiments

Since the U.S. Department of Energy (DOE)’s Office of Nuclear Energy (NE) initiated the Nuclear Energy University Program (NEUP) in 2009, a total of 30 NEUP projects focused on High-Temperature Gas-cooled Reactor (HTGR) thermal-fluid experiments were funded up to fiscal year (FY) 2021. This represents a total DOE investment of approximately $23M over the 12-year period, covering thermal fluid phenomena important to both pebble bed and prismatic HTGR designs. The NEUP projects have produced a large amount of high-quality experimental and computational data that were published in final project reports, journal articles, dissertations, and conference proceedings, but in most cases the actual data sets and supporting information such as facility and instrumentation descriptions were not publicly disseminated to the HTGR community. To the authors’ best knowledge, a data platform that organizes and summarizes these NEUP-funded projects for HTGR research does not currently exist. To improve access to this HTGR validation data and optimize the return on the significant investment made by DOE, the Advanced Reactor Technologies (ART) Gas-Cooled Reactor (GCR) program started a survey of completed and ongoing HTGR NEUP projects with the aim of developing a public-access data platform that can be used to retrieve computational fluid dynamics (CFD) and system code validation data and guide future NEUP investments. This paper summarizes the status of the current ART-GCR database, provides an overview of the NEUP-funded HTGR-related research projects from FY2009 to FY2021 and identify validation knowledge gaps still existing in HTGR thermal-fluid research.

42 ENGINEERING↗
DOE OSTI2024

Public Data Set: Initial Characterization of Electron Temperature and Density Profiles in PEGASUS Spherical Tokamak Discharges Driven Solely by Local Helicity Injection

This public data set contains openly-documented, machine readable digital research data corresponding to figures published in G.M. Bodner et al., ‘Initial Characterization of Electron Temperature and Density Profiles in PEGASUS Spherical Tokamak Discharges Driven Solely by Local Helicity Injection,’ Physics of Plasmas 28, 102504 (2021) and its erratum in Physics of Plasmas 31, 129904 (2024).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1994

Land surface temperature measurements for EOS MODIS data

Work accomplished includes: Beta delivery 1 of the MODIS LST product; the first version of MODIS LST ATBD; update of the atmospheric radiative transfer code ATRAD; the development of a new approach look-up table method; and improvement of the TIR spectrometer. Preliminary feasibility analysis of the look-up table approach is presented in terms of showing the effects on the TIR radiance at the top of the atmosphere of the stratospheric and upper atmospheric temperature profiles, the surface emissivity and temperature, the lower atmospheric temperature and water vapor profiles, and the viewing angle.

Wan, Zhengming↗