SEARCH · Search NASA

Results for “surface equivalent surface temperature”

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.

SourceResearch connectionFrom yearThrough year

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

At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

NASA NTRS1993

The Martian valley networks: Origin by niveo-fluvial processes

The valley networks may hold the key to unlocking the paleoclimatic history of Mars. These enigmatic landforms may be regarded as the Martian equivalent of the Rosetta Stone. Therefore, a more thorough understanding of their origin and evolution is required. However, there is still no consensus among investigators regarding the formation (runoff vs. sapping) of these features. Recent climatic modeling precludes warm (0 degrees C) globally averaged surface temperatures prior to 2 b.y. when solar luminosity was 25-30 percent less than present levels. This paper advocates snowmelt as the dominant process responsible for the formation of the dendritic valley networks. Evidence for Martian snowfall and subsequent melt has been discussed in previous studies.

Rice, J. W., Jr.↗

NASA NTRS2011

Hurricane Data Analysis Tool

In order to facilitate Earth science data access, the NASA Goddard Earth Sciences Data Information Services Center (GES DISC) has developed a web prototype, the Hurricane Data Analysis Tool (HDAT; URL: http://disc.gsfc.nasa.gov/HDAT), to allow users to conduct online visualization and analysis of several remote sensing and model datasets for educational activities and studies of tropical cyclones and other weather phenomena. With a web browser and few mouse clicks, users can have a full access to terabytes of data and generate 2-D or time-series plots and animation without downloading any software and data. HDAT includes data from the NASA Tropical Rainfall Measuring Mission (TRMM), the NASA Quick Scatterometer(QuikSCAT) and NECP Reanalysis, and the NCEP/CPC half-hourly, 4-km Global (60 N - 60 S) IR Dataset. The GES DISC archives TRMM data. The daily global rainfall product derived from the 3-hourly multi-satellite precipitation product (3B42 V6) is available in HDAT. The TRMM Microwave Imager (TMI) sea surface temperature from the Remote Sensing Systems is in HDAT as well. The NASA QuikSCAT ocean surface wind and the NCEP Reanalysis provide ocean surface and atmospheric conditions, respectively. The global merged IR product, also known as, the NCEP/CPC half-hourly, 4-km Global (60 N -60 S) IR Dataset, is one of TRMM ancillary datasets. They are globally-merged pixel-resolution IR brightness temperature data (equivalent blackbody temperatures), merged from all available geostationary satellites (GOES-8/10, METEOSAT-7/5 & GMS). The GES DISC has collected over 10 years of the data beginning from February of 2000. This high temporal resolution (every 30 minutes) dataset not only provides additional background information to TRMM and other satellite missions, but also allows observing a wide range of meteorological phenomena from space, such as, hurricanes, typhoons, tropical cyclones, mesoscale convection system, etc. Basic functions include selection of area of interest and time, single imagery, overlay of two different products, animation,a time skip capability and different image size outputs. Users can save an animation as a file (animated gif) and import it in other presentation software, such as, Microsoft PowerPoint. Since the tool can directly access the real data, more features and functionality can be added in the future.

Liu, Zhong↗

NASA NTRSDate not supplied

TECHNO-ECONOMIC ANALYSIS OF A CRYOGENIC FLUX CAPACITOR FOR GRID STORAGE

Joshua Schmitt↗

NASA NTRS1984

The role of surface generated radicals in catalytic combustion

The role of surface generated OH radicals in determining the catalytic ignition characteristics for propane oxidation on platinum were studied. The experiments were conducted in a stacked-plate, catalyst bed. Transient measurements, during catalytic ignition, of the catalyst's axial temperature profile were made and the effect of equivalence ratio, inlet temperature and inlet velocity was investigated. These measurements will provide insights which will be useful in planning and interpreting to OH measurements. Attempts to measure OH concentration in the catalyst bed using resonance absorption spectroscopy were unsuccessful, indicating that OH concentrations are below 10 to the 16th power/cc but still possibly above equilibrium values. Measurements are currently underway using forward scatter laser induced fluorescence which should extend the OH detection limits several orders of magnitude below the equilibrium concentrations.

Santavicca, D. A.↗

NASA NTRS2017

GEER Status Update

History: The Glenn Extreme Environments Rig (GEER) first became operational in the early part of 2015. Since that time GEER has completed a number of scientific tests and has undergone improvements in the chemical delivery system and analytics following a year of operations experience. Recent Updates: In June 2016, the GEER process system was rebuilt to provide a more robust system, higher accuracy and new capabilities. New insulation was installed on the exterior of the pressure vessel and gas lines. The newly revamped GEER plumbing system can provide extremely precise custom gas mixtures using any gas desired by the investigator in any combination. GEER can heat the resulting mixture up to 500 deg C and 1500 psia. The 304 stainless steel vessel walls were polished to reduce corrosion rate and reduce unwanted chemical reactions. The process lines were replaced with high purity Sulfinert coated tubing. The GEER team added the ability to individually boost specialty gases to GEER thus allowing operators to make very precise changes to the gas chemistry inside of GEER during a test while at high temperature and pressure. High accuracy mass flow meters were added to further improve gas mixing accuracy and precision. An in-line, integrated Inficon MicroGC Fusion was added for real time gas analysis along with a high purity gas sampling system, providing fully automated, real time analysis of the gas chemistry inside of GEER in minutes. This complements a co-located mass spectrometer and both are used for regular monitoring of the vessel chemistry. All internal vessel components were replaced with polished 304SS equivalents. Hot vent down capability was increased. Finally, an automated liquid injection system was added and is rated for max vessel operating conditions of (1500 psia, 500 C). Recent Results and Publications: In May 2016, GEER completed a test that exposed high temperature electronics to Venus surface conditions for 21.5 days. This demonstrated the potential for operating robotic spacecraft in the Venus environment without the need for thermal or environmental protection. Results from this test were published in December 2016 and received national media attention. In April 2017 GEER implemented an 80 day test at Venus surface conditions to simulate chemical weathering of expected Venus minerals. This test supported a ROSES award to a team led by Prof. Ralph Harvey of Case Western Reserve University. The test concluded in July 2017 and nearly doubled previous operation record of 42 days at Venus surface conditions. Preliminary results of these and previous experiments were presented at the recent Venus Modeling Workshop. In June 2017, NASA TM2017-219437 "Chemical and Microstructural Changes in Metallic and Ceramic Materials Exposed to Venusian Surface Conditions" was published. This report provides an extensive and valuable resource detailing the behavior of a variety of engineering materials at Venus surface conditions. Community Involvement: An external science advisory panel has been formed.

Kremic, Tibor↗

NASA NTRS2003

Behavior of Three Metallic Alloys under Combined Axial-Shear Stresses at Elevated Temperature

Type 316 stainless steel, Haynes 188, and Inconel 718 samples were subjected to an axial-shear strain controlled loading history while the specimen temperature was held at 650 C to quantify the evolution of material state under a complex biaxial load path when the material is in the viscoplastic domain. Yield surfaces were constructed in the axial-shear stress plane using a sensitive, 30 x 10(exp -6)m/m, equivalent offset strain definition for the yield strain. Subsequent yield surfaces were constructed at various points along the strain path to define the material evolution. These subsequent yield surface translated, expanded, and distorted relative to the initial yield surface. Each of these very different materials exhibited components of isotropic, kinematic and distortional hardening. Furthermore, subsequent yield surfaces for each material have a very well defined front face and a poorly defined, flattened, back side.

Colaiuta, J. F.↗

NASA NTRSDate not supplied

Phase Transitions and Melting in the Venusian Basaltic Crust: Implications for Crustal Recycling

Understanding phase transitions and melting in the Venusian crust and the associated changes in density are critical to constrain crustal thickness, recycling, and remelting processes. For example, average surface conditions on Venus of 92 bars and 460 °C correspond to low-grade metamorphic conditions on Earth equivalent to hornfels- and greenschist-facies. Further, the primary igneous mineralogy in the Venusian crust should be replaced by metamorphic minerals over time and potentially melt, as temperatures and pressures increase with depth along geothermal gradients. Here, we use Perple_X (Connolly, 2005), a Gibbs free energy minimization program to calculates table phase equilibria over a range of pressure and temperature conditions for whole-rock compositions of a dry basalt, alkali basalt, and peridotite. Further, we extract mineral abundancies along five geotherms of 5, 10, 15, 20 and 25 °C/km and calculate the rock density after the extraction of melt. On the coldest geotherm of 5 °C/km, melting would start at ~ 197 km and ~121 km in the basalt and alkali basalt, respectively, and therefore at depths that significantly exceed the estimated thickness of the Venusian crust (8-25 km). A density cross-over, where the crustal density would exceed that of the mantle could potentially induce delamination and is estimated to occur at ~ 40 km for both compositions. On the 10 °C/km geotherm, melting of the basalt starts at 65 km and melt extraction only causes a gradual densification due the formation of initially lower melt proportions. In contrast, the alkali basalt starts to melt at a depth of ~ 57 km and the subsequent densification of the residual composition could trigger delamination at ~ 60km depth. For hotter geotherms (i.e., 25 °C/km gradient), melting would occur at shallower depths of 21 – 23 km. However, the basalt will not get significantly denser than the mantle while the residuum of the alkali basalt would reach a density cross-over at 30 km. Hence, differences in Venusian crustal compositions can significantly influence the thickness of the crust on individual geotherms. Our results demonstrate that phase transitions and melting are strongly dependent on the assumed geotherm and could, combined with geodynamic models, further constrain crustal parameters.

Julia Semprich↗

NASA NTRS1977

Occultation of Epsilon Geminorum by Mars. II - The structure and extinction of the Martian upper atmosphere

The occultation of Epsilon Geminorum by Mars on April 8, 1976, was observed at three wavelengths and 4-ms time resolution with the 91-cm telescope aboard NASA's G. P. Kuiper Airborne Observatory. Temperature, pressure, and number-density profiles of the Martian atmosphere were obtained for both the immersion and emersion events. Within the altitude range 50-80 km above the mean surface, the mean temperature is about 145 K, and the profiles exhibit wavelike structures with a peak-to-peak amplitude of 35 K and a vertical scale of about 20 km. The ratio of the refractivity of the atmosphere at 4500 A and 7500 A is consistent with the atmospheric composition measured by Viking 1. From the 'central flash' - a bright feature in the light curve midway between immersion and emersion - an optical depth at 4500 A of 3.3 + or - 1.7 per km atm (about 0.23 per equivalent Martian air mass) is found for the atmosphere about 25 km above the mean surface near the south polar region. This large value and its weak wavelength dependence rule out Rayleigh scattering as the principal cause of the observed extinction.

Elliot, J. L.↗

DOE OSTI2023

Development of an Advanced Hydrogen Energy Storage System using Aerogel in a Cryogenic Flux Capacitor

The Cryogenic Flux Capacitor (CFC) is a cold, dense fluid storage core with integrated design features that afford the designer flexibility and provide new possibilities for the storage and discharge of energy. The stored energy, in this case, is represented by hydrogen physically bonded within the nanoscale pores within the aerogel composite blanket material, and the process of bonding or debonding is governed by the principles of physical adsorption (physisorption) and thermodynamics. The large surface area afforded by the nanoporous aerogel (~1,000 m 2 /g) allows for storage densities close to, or in some cases exceeding, that of normal boiling point liquids. Its performance easily exceeds what can be achieved via ambient temperature and high-pressure gas storage for an equivalent volume. CFC storage is predicted to be easily scalable, constructed from readily available commercial materials, and lends itself to a range of pressure applications. The project team designed and manufactured the CFC, integrating it into a set of temperature-controlled flow loops. The CFC test setup was validated against existing data from previous NASA work. Tests used bottled hydrogen gas for test validation. A cryogenic fluid, nitrogen, flowed through a metered control system. Hydrogen temperature, pressure, and flow rates, as well as the temperature control targets, provided all necessary control targets. The team analyzed the recorded data and updated the Technology Maturation Plan based on the results of the test, making recommendations for a follow-up test, scale-up, and maturation pathway. For the engineering development and maturation of CFC hydrogen storage technology, a Techno-Economic Assessment (TEA) and Commercialization Plan for the integration of this technology with various power generation assets were produced. A companion analytical model was developed, experimentally validated, compared against performance metric, and used to tune the model and scale up the technology.

08 HYDROGEN↗

NASA NTRS2017

High-Spatial-Resolution OH PLIF Visualization in a Cavity-Stabilized Ethylene-Air Turbulent Flame

High-spatial-resolution OH planar laser-induced fluorescence was measured for a premixed ethylene-air turbulent flame in an electrically-heated Mach 2 continuous-flow facility (University of Virginia Supersonic Combustion Facility, Configuration E.) The facility comprised a Mach 2 nozzle, an isolator with flush-wall fuel injectors, a combustor with optical access, and an extender. The flame was anchored at a cavity flameholder with a backward-facing step of height 9 mm. The temperature-insensitive Q1(8) transition of OH was excited using laser light of wavelength 283.55 nm. A spatial filter was used to create a laser sheet approximately 25 microns thick based on full-width at half maximum (FWHM). Extension tubes increased the magnification of an intensified camera system, achieving in-plane resolution of 40 microns based on a 50% modulation transfer function (MTF). The facility was tested with total temperature 1200 K, total pressure 300 kPa, local fuel/air equivalence ratios of approximately 0.4, and local Mach number of approximately 0.73 in the combustor. A test case with reduced total temperature and another with reduced equivalence ratio were also tested. PLIF images were acquired along a streamwise plane bisecting the cavity flameholder, from the backward facing step to 120 mm downstream of the step. The smallest observed features in the flow had width of approximately 110 microns. Flame surface density was calculated for OH PLIF images.

Geipel, Clayton M.↗

DOE OSTI2023

Commissioning of a two-target DC cylindrical magnetron sputter coater for depositing Nb 3 Sn film on Nb superconducting radiofrequency cavities

A DC cylindrical magnetron sputter coater was commissioned and used to coat Nb 2.6 GHz superconducting radiofrequency (SRF) cavity with Nb 3 Sn. The sputter coater has two identical cylindrical magnetrons that can move, with a controlled speed, along the axis of the SRF cavity to coat the inside surface of the cavity. The design of the sputter coater is discussed, along with its performance. Initially, a sample holder that allows coating on flat substrates at positions similar to the equator and beam tubes of a 2.6 GHz SRF cavity was used to test conditions for fabricating Nb 3 Sn layers. Multilayers of Nb and Sn were sequentially sputtered on flat Nb and sapphire substrates mounted on the equivalent positions of the cavity's beam tubes and the equator using the two identical cylindrical magnetrons. Then, the Nb/Sn multilayers were annealed at 950 °C for 3 h. Here, the ~1.2 μm thick Nb 3 Sn film did not show any other Nb–Sn compounds and had a superconducting transition temperature of 17.61–17.76 K. The 2.6 GHz SRF cavity was coated using similar conditions as flat samples. Cryogenic RF testing of the Nb 3 Sn-coated cavity demonstrated a quality factor of 3.2 × 10 8 at an accelerating gradient of 5 MV/m at 4.4 K.

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

20% of US electricity from wind will have limited impacts on system efficiency and regional climate

Abstract Impacts from current and future wind turbine (WT) deployments necessary to achieve 20% electricity from wind are analyzed using high resolution numerical simulations over the eastern USA. Theoretical scenarios for future deployments are based on repowering (i.e. replacing with higher capacity WTs) thus avoiding competition for land. Simulations for the contemporary climate and current WT deployments exhibit good agreement with observed electricity generation efficiency (gross capacity factors (CF) from simulations = 45–48%, while net CF for WT installed in 2016 = 42.5%). Under the scenario of quadrupled installed capacity there is a small decrease in system-wide efficiency as indicated by annual mean CF. This difference is approximately equal to that from the two simulation years and may reflect saturation of the wind resource in some areas. WT modify the local near-surface climate in the grid cells where they are deployed. The simulated impact on near-surface climate properties at both the regional and local scales does not increase with increasing WT installed capacity. Climate impacts from WT are modest compared to regional changes induced by historical changes in land cover and to the global temperature perturbation induced by use of coal to generate an equivalent amount of electricity.

17 WIND ENERGY↗

DOE OSTI2020

Compiled TBS data from Oliktok Point from ICARUS, AVPOP, and POPEYE

The dataset encompasses QA/QC TBS data, including TBS altitude, atmospheric pressure, dew point, POPs number concentrations and mean aerosol size, relative humidity, temperature, equivalent potential temperature, equivalent temperature, and date and time. These data are provided per day for at least one TBS flight. Supporting data from the AMF3 aligned with the timestamps of the TBS data include cloud base distance from TBS, if the time corresponds to cloud base transit of the TBS, surface-based pressure, surface-based precipitation rate, surface-based UHSAS data, ceilometer cloud base height, KAZR cloud top height, and MWR liquid water content. Both POPS and UHSAS aerosol number concentrations are provided as: (1) absolute (i.e. concentrations for each instrument's total size range) and (2) the overlapping size range (i.e. the same size bins for both instruments).

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1979

The erosion/corrosion of small superalloy turbine rotors operating in the effluent of a PFB coal combustor

Superalloy turbine rotors in a single stage turbine with 6 percent partial admittance were operated in the effluent of a pressurized fluidized bed coal combustor for up to 164 hours. Total mass flow was 300 kg/hr and average particulate loadings ranged from 600 to 2800 ppm for several coal/sorbent combinations. A 5.5 atm turbine inlet gas pressure and inlet gas temperatures from 700 to 800 C yielded absolute gas velocities at the stator exit of about 500 m/s. The angular rotation speed (40,000 rpm) of the six inch diameter rotors was equivalent to a tip speed of about 300 m/s, and average gas velocities relative to the rotating surface ranged from 260 to 330 m/s at mean radius. The rotor erosion pattern reflects heavy particle separation with severe (5 to 500 cm/yr) erosion at the leading edge, pressure side center, and suction side trailing edge at the tip. The erosion distribution pattern provides a spectrum of erosion/oxidation/deposition as a function of blade position. This spectrum includes enhanced oxidation (10 to 100 x air), mixed oxides in exposed depletion zones, sulfur rich oxides in deposition zones, and rugged areas of erosive oxide removal.

Zellars, G. R.↗

NASA NTRS1980

Temporal variations in regional models of the Sargasso Sea from GEOS-3 altimetry

The paper considers temporal variations in regional models of the Sargasso sea from GEOS-3 telemetry. The methods of regional models and the analysis of overlapping passes are utilized, and short-wave maxima and minima in the regional surface models are examined for correlations with surface and remote sensed infrared temperature data supplemented with subsurface expendable bathythermograph data (XBT). The analysis of overlapping passes provide a better picture of instanteneous sea surface height (SSH) variability through wavelengths greater than 30 km. Correlation studies with cyclonic and anticyclonic ocean eddies from infrared imagery and XBT data indicate satisfactory agreement with equivalent SSH features 98% of the time if the time varying factors are allowed for.

Mather, R. S.↗

DOE OSTI2022

Date Release Report for Large Surface Explosion Coupling Experiment (LSECE) Nevada National Security Site

The DTRA sponsored 2020-2022 Large Surface Explosion Coupling Experiment (LSECE) consists of two large ground surface chemical explosions, data collection, analysis and modeling carried out in 2020-2022. The LSECE chemical explosions were carried out at the site of prior NNSA sponsored buried chemical explosions that were part of the Source Physics Experiment (SPE) Phase II in Dry Alluvium Geology (DAG). This report described the data collected under LSECE that is being made publicly available. The prior buried explosion DAG data are described in a separate report (https://www.osti.gov/biblio/1825534) and are also publicly available. The LSECE explosions, data analysis and numerical modeling work sponsored by DTRA were intended to address three objectives: 1) Generate seismo-acoustic data to test and improve numerical models of explosion energy coupling in dry alluvium geology; 2) To improve seismo-acoustic yield estimation techniques as a function of depth and medium properties; 3) To study and improve acoustic propagation modeling under two different atmospheric conditions. The LSECE data that were collected have expanded the prior DAG buried explosion dataset to include surface chemical explosions recorded on a common set of seismo-acoustic stations. They have allowed a more detailed study of above and below surface seismo-acoustic energy coupling with applications to explosion monitoring and assessment. The two approximately 1-ton TNT equivalent yield LSECE explosions were detonated at different times of the day to explore the effects of the different atmospheric conditions. The first chemical explosion “Artemis” was conducted before dawn when temperature inversions were present. The second chemical explosion “Apollo” was conducted on a sunny afternoon when the temperature gradient was more linear. The LSECE chemical explosion data were also collected across a variety of different sensor types to allow evaluation of their effectiveness in recovering useful information. The LSECE instrumentation included fiber optic or Distributed Acoustic Sensing (DAS), a dense array or Large-N array of seismometers, borehole accelerometers, DAS and a velocity meter, airborne acoustic instruments and a variety of visual and remote sensing data.

58 GEOSCIENCES↗

NASA NTRS2017

Chapter 8: Droughts, Floods, and Wildfires

Recent droughts and associated heat waves have reached record intensity in some regions of the United States; however, by geographical scale and duration, the Dust Bowl era of the 1930s remains the benchmark drought and extreme heat event in the historical record (very high confidence). While by some measures drought has decreased over much of the continental United States in association with long-term increases in precipitation, neither the precipitation increases nor inferred drought decreases have been confidently attributed to anthropogenic forcing. The human effect on recent major U.S. droughts is complicated. Little evidence is found for a human influence on observed precipitation deficits, but much evidence is found for a human influence on surface soil moisture deficits due to increased evapotranspiration caused by higher temperatures. Future decreases in surface (top 10 cm) soil moisture from anthropogenic forcing over most of the United States are likely as the climate warms under higher scenarios. Substantial reductions in western U.S. winter and spring snowpack are projected as the climate warms. Earlier spring melt and reduced snow water equivalent have been formally attributed to human-induced warming (high confidence) and will very likely be exacerbated as the climate continues to warm (very high confidence). Under higher scenarios, and assuming no change to current water resources management, chronic, long-duration hydrological drought is increasingly possible by the end of this century. Detectable changes in some classes of flood frequency have occurred in parts of the United States and are a mix of increases and decreases. Extreme precipitation, one of the controlling factors in flood statistics, is observed to have generally increased and is projected to continue to do so across the United States in a warming atmosphere. However, formal attribution approaches have not established a significant connection of increased riverine flooding to human-induced climate change, and the timing of any emergence of a future detectable anthropogenic change in flooding is unclear. The incidence of large forest fires in the western United States and Alaska has increased since the early 1980s and is projected to further increase in those regions as the climate warms, with profound changes to certain ecosystems.

Wehner, M. F.↗

NASA NTRS1982

Development of cast ferrous alloys for Stirling engine application

Low cost cast ferrous base alloys that can be used for cylinder and regenerator housing components of the Stirling engine were investigated. The alloys must meet the requirements of high strength and thermal fatigue resistance to approximately 1500 F, compatibility and low permeability with hydrogen, good elevated temperature oxidation/corrosion resistance, and contain a minimum of strategic elements. The phase constituents of over twenty alloy iterations were examined by X-ray diffraction. These alloy candidates were further screened for their tensile and stress rupture strength and surface stability in air at 1450 and 1600 F, respectively. Two alloys, NASAUT 1G (Fe-10Mn-20Cr-1.5C-1.0Si) and NASAUT 4G (Fe-15Mn-12Cr-3Mo-1.5C-1.0Si-1.0Nb), were chosen for more extensive elevated temperature testing. These alloys were found to exhibit nearly equivalent elevated temperature creep strength and oxidation resistance. Silicon present in these alloys at the 1 w/o level permitted the achievement of oxide scale adherence to 1600 F without loss of strength (or ductility) as was noted for equivalent additions of aluminum.

Lemkey, F. D.↗