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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Deep Solar Activity Minimum 2007-2009: Solar Wind Properties and Major Effects on the Terrestrial Magnetosphere

We discuss the temporal variations and frequency distributions of solar wind and interplanetary magnetic field parameters during the solar minimum of 2007 - 2009 from measurements returned by the IMPACT and PLASTIC instruments on STEREO-A.We find that the density and total field strength were significantly weaker than in the previous minimum. The Alfven Mach number was higher than typical. This reflects the weakness of magnetohydrodynamic (MHD) forces, and has a direct effect on the solar wind-magnetosphere interactions.We then discuss two major aspects that this weak solar activity had on the magnetosphere, using data from Wind and ground-based observations: i) the dayside contribution to the cross-polar cap potential (CPCP), and ii) the shapes of the magnetopause and bow shock. For i) we find a low interplanetary electric field of 1.3+/-0.9 mV/m and a CPCP of 37.3+/-20.2 kV. The auroral activity is closely correlated to the prevalent stream-stream interactions. We suggest that the Alfven wave trains in the fast streams and Kelvin-Helmholtz instability were the predominant agents mediating the transfer of solar wind momentum and energy to the magnetosphere during this three-year period. For ii) we determine 328 magnetopause and 271 bow shock crossings made by Geotail, Cluster 1, and the THEMIS B and C spacecraft during a three-month interval when the daily averages of the magnetic and kinetic energy densities attained their lowest value during the three years under survey.We use the same numerical approach as in Fairfield's empirical model and compare our findings with three magnetopause models. The stand-off distance of the subsolar magnetopause and bow shock were 11.8 R(sub E) and 14.35 R(sub E), respectively. When comparing with Fairfield's classic result, we find that the subsolar magnetosheath is thinner by approx. 1 R(sub E). This is mainly due to the low dynamic pressure which results in a sunward shift of the magnetopause. The magnetopause is more flared than in Fairfield's model. By contrast the bow shock is less flared, and the latter is the result of weaker MHD forces.

solar minimum↗
NASA NTRS2006

Electron Velocity Distribution Function in Magnetic Clouds in the Solar Wind

We present a study of the kinetic properties of the electron velocity distribution functions within magnetic clouds, since they are the dominant thermal component. The study is based on high time resolution data from the GSFC WIND/SWE electron spectrometer and the Berkeley 3DP electron plasma instruments. Recent studies on magnetic clouds have shown observational evidence of anti-correlation between the total electron density and electron temperature, which suggest a polytrope law P(sub e) = alpha(Nu(sub e) (sup gamma)) for electrons with the constant gamma approximates 0.5 < 1. This anti-correlation and small polytropic gamma-values is interpreted in the context of the presence of highly non-Maxwellian electron distributions (i.e. non-thermal) within magnetic clouds. These works suggested that the non-thermal electrons can contribute as much as 50% of the total electron pressure within magnetic clouds. We have revisited some of the magnetic cloud events previously studied and attempted to quantify the nature of the non-thermal electrons by modeling the electron velocity distribution function using a kappa distribution function to characterize the kinetic non-thermal effects. If non-thermal tail effects are the source for the anti-correlation between the moment electron temperature and density and if the kappa distribution is a reasonable representative model of non-thermal effects, then the electron velocity distribution within magnetic clouds should show indication for small K-values when gamma < 1.

Nieves-Chinchil, Teresa↗
DOE OSTI2026

U.S. Department of Energy Competitiveness Improvement Project (CIP) 2024 Inverter Listing Awardee: Eocycle America Corporation

This fact sheet describes the 2024 Competitiveness Improvement Project (CIP) award received by Eocycle America Corporation for Inverter Listing. The U.S. Department of Energy's (DOE's) CIP awards cost-shared subcontracts and technical support to manufacturers of small and medium-sized wind turbines. Managed by NLR on behalf of DOE, CIP helps advance wind energy as a cost-effective, distributed generation technology option.

17 WIND ENERGY↗
NASA NTRS2000

X-Ray Line Spectroscopy of Massive X-Ray Binaries

Spectra from ASCA have provided the most, detailed view to date of the X-ray spectral properties of stellar winds in massive X-ray binaries. Using detailed atomic models that account for recombination cascade kinetics, we have reexamined archival data from Vela X-1 and Cen X-3 in the context of simple models of their wind geometries and velocity distributions. Our approach emphasizes apparent differential emission measure (DEM) distributions, and their dependence on orbital phase and wind parameters. A grid of theoretical DEM distributions is used to generate model spectra, which are compared to the data. We obtain good fits, and derive constraints oil the stellar wind parameters. We provide a summary of the method, and show that, even though the companion stars in Vela X-1 and Cen X-3 have comparable mass-loss rates, the winds in these two systems are dramatically different, in character.

Liedahl, D. A.↗
DOE OSTI2023

Competitiveness Improvement Project (CIP)

Through the Competitiveness Improvement Project (CIP), the U.S. DOE supports small businesses who design and manufacture small or medium wind turbine technology through cost-shared subcontracts awarded via a competitive process. The goals of the CIP are to: improve cost competitiveness with other distributed generation technology through optimized designs and advanced manufacturing processes; increase the number of certified small and medium wind turbine designs across a wide range of sizes; and accelerate deployment of improved, certified distributed wind energy technology. NREL manages the projects through a defined period of performance subcontract, providing technical monitoring and coordinating technical assistance from DOE labs.

advanced manufacturing↗
NASA NTRS2010

The Sensitivity of Simulated Ocean Biogeochemistry to Forcing Fields Derived from NCEP and MERRA Reanalysis Products

Ocean biogeochemistry models are typically forced by atmospheric and oceanic data derived from reanalysis products. For the NASA Ocean Biogeochemistry Model (NOBM) such reanalysis forcing fields include: surface wind stress, sea surface temperature, ice distributions, shortwave radiation, surface wind speeds and surface atmospheric pressure. Additionally, proper computation of ocean irradiance requires reanalysis products of relative humidity and precipitable water (in addition to aerosol and cloud information which is derived from satellite data). The question posed here is, does the choice of reanalysis products make a difference in the representation of ocean biology and biogeochemistry? NOBM was forced by NCEP and MERRA reanalysis products for the period 2002-2009. We find that in 2009 global distributions and abundances of biological variables (total chlorophyll and nutrients) and carbon (dissolved inorganic and organic carbon and surface pCO2) were similar between the two different forcing fields. Global statistical comparisons with satellite and in situ data also showed negligible differences.

Gregg, Watson↗
NASA NTRS1975

An investigation in the NASA MSFC 14-inch trisonic wind tunnel to determine the pressure distribution over the components of a 0.004 scale version of the Rockwell MCR 0074 baseline shuttle ascent configuration (IA32F), volume 1

Data were obtained for Mach numbers from 0.6 to 3.48, angles of attack from -10 to 10 degrees, and angles of sideslip from -10 to 10 degrees at zero angle of attack. Also, -4 and 4 degrees sideslip were run for an angle of attack of -5 and 5 degrees. Aerodynamic configurations of the solid rocket motors, external tank, and orbiter are shown. Graphs of plotted pressure data (pressure coefficients) for the external tank and solid rocket motors are given. A description of the test facility is included.

Ramsey, P. E.↗
NASA NTRS1975

Results of an Investigation of the 0.003-scale Space Shuttle External Tank MSFC Model 460 in the NASA/MSFC 14 x 14-inch Trisonic Wind Tunnel to Determine Static Pressure Distributions During Reentry (TA2F), Volume 1

Objectives of the test were to obtain static pressure distributions for the ET at reentry conditions. Basic configuration of the model was the MCR 0200 ET modified to include a rectangular crossbar at the aft ET/orbiter attach point. Mach numbers were 1.96, 3.48, and 4.96. Reynolds number per foot at these Mach numbers were 6.95 million, 6.42 million, and 4.95 million, respectively. Angle of attack range was -8 to 100 degrees and roll angle was 0 to 315 degrees. Occupancy hours were 104.

Ramsey, P. E.↗
NASA NTRS1975

Results of an investigation of the 0.003-scale space shuttle external tank MSFC model 460 in the NASA/MSFC 14 x 14 inch Trisonic Wind Tunnel to determine static pressure distributions during reentry (TA2F), volume 3

Static pressure distributions for the external tank (ET) at reentry conditions are presented. Basic configuration of the model was the MCR 0200 ET modified to include a rectangular crossbar at the aft ET/orbiter attach point. Mach numbers were 1.96, 3.48, and 4.96. Reynolds number per foot at these Mach numbers were 6.95 million, 6.42 million, and 4.95 million, respectively. Angle of attack range was -8 to 100 degrees and roll angle was 0 to 315 degrees.

Ramsey, P. E.↗
DOE OSTI2020

Distributed Aerodynamic Control using Active Trailing-Edge Flaps for Large Wind Turbines

This work presents a numerical framework to investigate distributed aerodynamic control devices for application in large wind turbines. Tool capabilities were extended to facilitate multiple aerodynamic polar tables. The airfoil aerodynamics characteristics were automatically determined, and blade-pitch, generator-torque, and trailing-edge-flap controllers were tuned in-the-loop according to a specific blade design. This automated workflow allows analysis and optimization of trailing-edge flaps, enabling codesign studies. Results targeted reductions of root-flap-bending moment derivatives. The applied trailing-edge-flap control reduced the standard deviation of root-flap-bending moments by more than 6% and benefit related parameters, e.g., reduce blade-tip deflections, by up to 8%. Because of varying thrust distributions along the blade span, different flap designs have nonlinear characteristics in terms of the control objective and show best performance when located at the radial position with maximum thrust. In general, larger flaps provide a greater influence to reduce the target control objective.

17 WIND ENERGY↗
NASA NTRS1995

Heating and scattering of ring-beam distributions by turbulence

Pickup ions in the solar wind are initially are born in ring-beam distributions, i.e. f(v) varies as delta(v(sub perpendicular) - V(sub sw)sin(Theta)) delta(v(sub parallel) - V(sub sw)cos(Theta)), where Theta is the angle between the solar wind velocity and the IMF(Interplanetary Magnetic Field), and V(sub sw) is the solar wind speed. Often the distribution has been presumed to relax to a distribution that is isotropic in Theta and essentially mono-energetic, a shell or a 'bi-spherical distribution.' However solar wind turbulence is capable of heating the ring distribution on the timescale of a few tens of gyroperiods, a timescale not greatly distinct from that required for pitch angle scattering to a shell. To describe this effect, we have performed test-particle studies of the heating/scattering of the ring beam distribution by MHD turbulence, adopting various models for the MHD fluctuations, including slab and fully dynamic 2D and 3D incompressible turbulence. Furthermore, a system composed of a cold ion ring and a background plasma is unstable to several kinetic plasma instabilities. We carried out kinetic simulations of the ring beam distribution, showing that plasma instabilities also rapidly energize and scatter particles. Results will be presented comparing relaxation and heating rates of the ring-beam distribution by the various mechanisms.

Gray, P. C.↗