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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Non-Maxwellian velocity distribution functions associated with steep temperature gradients in the solar transition region. Paper 1: Estimate of the electron velocity distribution functions

It was shown that, in the presence of the steep temperature gradients characteristic of EUV models of the solar transition region, the electron and proton velocity distribution functions are non-Maxwellian and are characterized by high energy tails. The magnitude of these tails are estimated for a model of the transition region and the heat flux is calculated at a maximum of 30 percent greater than predicted by collision-dominated theory.

Roussel-Dupre, R.↗
NASA NTRS1987

Distribution of total ozone and stratospheric ozone in the tropics - Implications for the distribution of tropospheric ozone

Climatologies of total columnar ozone and integrated stratospheric ozone amounts at low latitudes (15 deg N to 15 deg S), derived from satellite observations, are presented. A significant longitudinal variability in total ozone is present, with highest values generally located between 60 deg W and 60 deg E. The integrated stratospheric component of total ozone, on the other hand, does not exhibit a longitudinal preference for high values. Therefore it is hypothesized that the climatological longitudinal distribution of total ozone reflects the variability of the abundance of tropospheric ozone at low latitudes. Furthermore, it is speculated that in situ photochemical production of ozone resulting from biomass burning may be responsible for the observed enhancement of total ozone at these longitudes.

Fishman, Jack↗
NASA NTRS1988

A reference standard for bidirectional reflection distribution function and bidirectional transmission distribution function measurement

A Lambertian reference standard for uniformly scattering a beam of light is constructed of a plate having a planar surface with a layer of glue disposed on the surface. An evenly packed layer of monodisperse spheres is set in the layer, and when the standard is used for bi-directional (BRDF) measurements, the spheres are coated with a layer of highly relective substance, such as gold or silver. When the standard is used for bi-directional transmittance distribution function (BTDF) measurements, the spheres are of a transparent material and are provided with a roughened surface, as by acid etching. In this case, the layer of glue is an optical cement, and the plate is of glass, with the spheres, the layer, and the plate all possessing a similar refractive index.

Witherow, William K.↗
NASA NTRS1991

Development of a Weibull posterior distribution by combining a Weibull prior with an actual failure distribution using Bayesian inference

A Bayesian inference process for system logistical planning is presented which provides a method for incorporating actual failures with prediction data for an ongoing and improving reliability estimates. The process uses the Weibull distribution, and provides a means for examining and updating logistical and maintenance support needs.

Giuntini, Michael E.↗
NASA NTRS1952

A Comparison of the Chordwise Pressure Distribution and Spanwise Distribution of Loading at Subsonic Speeds on Two Triangular Wings of Aspect Ratio 2 Having NACA 0005 and 0008 Sections

Measurements of the distribution of surface pressures were made on two wing-body combinations employing a triangular wing having an aspect ratio ratio of 2. The first of these combinations had a wing with the NACA 0008-63 section parallel to the air stream while the wing of the second had the NACA 0005-63 section in the stream direction. The measurements were made for Mach numbers from 0.11 to 0.95 at a constant Reynolds number of 3.0 million. Data were also obtained for Reynolds numbers up to 15.0 million at the lower Mach number. A summary of data obtained from previously published force tests of these same models is also included for completeness of the presentation of the effect of wing thickness.

Smith, Donald W↗
NASA NTRS1937

Energy Loss, Velocity Distribution, and Temperature Distribution for a Baffled Cylinder Model, Special Report

In the design of a cowling a certain pressure drop across the cylinders of a radial air-cooled engine is made available. Baffles are designed to make use of this available pressure drop for cooling. The problem of cooling an air-cooled engine cylinder has been treated, for the most part, from considerations of a large heat-transfer coefficient. The knowledge of the precise cylinder characteristics that give a maximum heat-transfer coefficient should be the first consideration. The next problem is to distribute this ability to cool so that the cylinder cools uniformly. This report takes up the problem of the design of a baffle for a model cylinder. A study has been made of the important principles involved in the operation of a baffle for an engine cylinder and shows that the cooling can be improved 20% by using a correctly designed baffle. Such a gain is as effective in cooling the cylinder with the improved baffle as a 65% increase in pressure drop across the standard baffle and fin tips.

Brevoort, Maurice J.↗
DOE OSTI2026

How Distributed Energy Resources Can Support Resilience in Utility Distribution Networks

The goal of this webinar is to engage with electric utilities in the Midwest, particularly small public utilities, to understand the industry's needs for science tools to plan for winter resilience in the future, designing tools that will benefit electric power resilience in all communities. Michigan Tech leads this project with partners from multiple academic, government, and industry groups and asked NLR to present on DERs and laboratory tools and resources.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2025

Comprehensive Analysis of the Relative Dispersion of Droplet-Size Distributions and Their Relationships to Key Physical Fog Processes Under Different Aerosol Conditions and Evolutionary Stages

The relative dispersion of cloud and fog droplets has significant impacts on aerosol indirect effects, radiative transfer, and microphysical processes. However, previous studies have been mostly concerned with clouds, with limited studies on fog, particularly those that examine the combined influences of all key physical processes and their roles during fog evolution. As such, this study aims to conduct a comprehensive investigation by examining the relationships between relative dispersion and other microphysical variables, as well as the underlying microphysical and dynamic processes, based on field fog campaigns in polluted and clean conditions. In polluted fog, droplet concentrations are higher, leading to smaller droplets and increased dispersion. The correlation between dispersion and droplet volume-mean radius is positive in the polluted fog, but shifts to negative in clean fog. Here, we attribute the difference to various microphysical processes like aerosol activation, condensation, collision-coalescence, and entrainment-mixing. In polluted fog, high aerosol concentrations, low supersaturations, and strong turbulence (entrainment-mixing) provide suitable conditions for the simultaneous occurrence of droplet condensation and aerosol activation, resulting in a positive correlation between dispersion and volume-mean radius, especially during the fog formation stage. In contrast, during the mature stage in clean fog, condensation is dominant with weak aerosol activation leading to a negative correlation between relative dispersion and volume-mean radius. The collision-coalescence process is more active in the mature stage, increasing radii and leading to the negative correlation between dispersion and volume-mean radius. This result sheds new light on understanding the relative dispersion and mechanisms in fog under different aerosol backgrounds.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1937

Energy Loss, Velocity Distribution, and Temperature Distribution for a Baffled Cylinder Model

A study has been made of the important principles involved in the operation of a baffle for an engine cylinder and shows that cooling can be improved by 20 percent by using a correctly designed baffle. Such a gain is as effective as a 65 percent increase in pressure drop across the standard baffle, which had a 1/4 inch clearance between baffle and fin tips.

Brevoort, Maurice J↗