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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

An analysis of spanwise gust gradient data

Plots of winds encountered during flight are presented for severe turbulence cases from flights 6 and 7 of the Joint Airport Weather Studies (JAWS) Project (McCarthy et al., 1982). During run 10 of flight 7, analyzed here in considerable detail, the B-57B Cambera aircraft showed a sharp increase in airspeed of 15 m/sec over a distance of about 130 m and then a more gradual decrease of 20 to 25 m/sec over a distance of about 2 km. This suspected outflow feature was associated with a downdraft exceeding 10 m/sec. The horizontal wind direction changed nearly 180 deg during the pass through the feature. Unexpectedly, the intensity of the velocity differences decreased for all three components within the downdraft. Calculated probability density functions for u, v, and w show a jagged character, whereas delta-u, delta-v, and delta-w show a much smoother, unimodal behavior. The distributions for delta-u, delta-v, and delta-w are distinctly non-Gaussian.

Campbell, W.↗
NASA NTRS1984

SASS wind forecast impact studies using the GLAS and NEPRF systems: Preliminary conclusions

For this project, a version of the GLAS Analysis/Forecast System was developed that includes an objective dealiasing scheme as an integral part of the analysis cycle. With this system the (100 sq km) binned SASS wind data generated by S. Peteherych of AER, Canada corresponding of the period 0000 GMT 7 September 1978 to 1200 GMT 13 September 1978 was objectively dealiased. The dealiased wind fields have been requested and received by JPL, NMC and the British Meteorological Office. The first 3.5 days of objectively dealiased fields were subjectively enhanced on the McIDAS system. Approximately 20% of the wind directions were modified, and of these, about 70% were changed by less than 90 deg. Two SASS forecast impact studies, were performed using the dealiased fields, with the GLAS and the NEPRF (Navy Environmental Prediction Research Facility) analysis/forecast systems.

Kalnay, E.↗
NASA NTRS1984

First global analysis of SEASAT scatterometer winds and potential for meteorological research

The first global wind fields from SEASAT-A scatterometer (SASS) data were produced. Fifteen days of record are available on tape, with unique wind directions indicated for each observation. The methodology of the production of this data set is described, as well as the testing of its validity. A number of displays of the data, on large and small scales, analyzed and gridded, are provided.

Peteherych, S.↗
NASA NTRS1983

NASA B-57B Severe Storms Flight Program

Plots of winds encountered in-flight are presented for a severe turbulence case from JAWS flight 7 (near Denver on the afternoon of July 15, 1982). During the flight the B-57B showed a 30-knot increase in airspeed over a distance of about 426 ft and then a more gradual decrease of 40 to 50 knots over a distance of about 3.2 miles. This suspected outflow feature was associated with downdraft in excess of 20 knots. The horizontal wind direction changed almost 180 deg during the pass through the feature, and the intensity of velocity differences decreased for all three components within the downdraft. Calculated probability density functions for u, v, and w showed a jagged character; and distributions for Delta-u, Delta-v, and Delta-w were distinctly non-Gaussian. Based on skewness and kurtosis values, the data could probably best be modeled by a Pearson type VII (Student's t) distribution.

Painter, W. D.↗
NASA NTRS1985

Estimates of Latent Heat in Clouds

Release of latent heat in formation of clouds and precipitation estimated more accurately with simple technique that merges satellite cloud imagery with rawinsonde (tracked-radiosonde) data on air pressure, temperature, humidity, windspeed, and wind direction. Technique created to improve diagnosis of energy states and transformations in extratropical cyclones.

Smith, P. J.↗
NASA NTRS1985

Transport of Venusian rolling 'stones' by wind?

Simulations of Venusian wind processes are described which show that particles are moved by 'rolling' at wind speeds as much as 30 percent lower than those required for saltation threshold. This mode of wind transport is only observed for sustained periods in water on earth; thus, there are similarities between aqueous fluid transport on earth and atmospheric transport on Venus. The formation of small sand ridges and grooves oriented parallel to the wind direction is associated with the rolling of grains in Venusian simulations and these structures may be unique aeolian features on Venus.

Greeley, R.↗
NASA NTRS1985

Evidence for ion heat flux in the light ion polar wind

Cold flowing hydrogen and helium ions have been observed using the retarding ion mass spectrometer on board the Dynamics Explorer 1 spacecraft in the dayside magnetosphere at subauroral latitudes. The ions show a marked flux asymmetry with respect to the relative wind direction. The observed data are fitted by a model of drifting Maxwellian distributions perturbed by a first order-Spritzer-Haerm heat flux distribution function. It is shown that both ion species are supersonic just equatorward of the auroral zone at L = 14, and the shape of asymmetry and direction of the asymmetry are consistent with the presence of an upward heat flux. At L = 6, both species evolve smoothly into warmer subsonic upward flows with downward heat fluxes. In the case of subsonic flows the downward heat flux implies a significant heat source at higher altitudes. Spin curves of the spectrometer count rate versus the spin phase angle are provided.

Biddle, A. P.↗
NASA NTRS1986

Prediction of the far field noise from wind energy farms

The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

Shepherd, K. P.↗
NASA NTRS1987

Hanging Windmills From Cables

Relatively inexpensive structure enables raising and lowering of windmills. Windmills supported, according to new concept, by hanging from cables. Possible to raise and lower windmills easily for maintenance and to lower them to avoid excessive windspeeds. Airframe consists of fuselage and empennage. Windmill turns shaft driving electrical generator. Device aerodynamically stable so it will rotate in yaw to maintain windmill in downwind position as wind direction changes.

Farmer, Moses G.↗
NASA NTRS1986

Day and night profiles of tropospheric nitrous oxide

Daytime and nighttime vertical profiles of the tropospheric trace gas N2O were determined from grab sample collections off the Atlantic and Gulf coasts of Florida. The grab samples were collected during the week of October 7-13, 1984, from a Lear jet during descent spirals over an altitude range of 12.5-0.3 km in approximately 1.2-km intervals. During this period there were two distinct airflow regimes sampled: (1) the surface boundary layer (less than 2 km), in which the wind direction was typically easterly; and (2) the regime above the boundary layer, which was predominantly characterized by westerly flow. N2O mixing ratios, normalized to dry air, were determined from 148 daytime and nighttime samplings. N2O was found to be uniformly mixed at all altitudes at 301.9 + or - 2.4 parts per billion by volume.

Cofer, Wesley R., III↗
NASA NTRS1987

An analysis of the shocklike electrostatic noise observed during AMPTE solar wind ion releases

Electrostatic waves produced by the interaction of the ion cloud with the solar wind are analyzed in order to explain the shocklike noise detected by the Ion Release Module instruments during the Active Magnetospheric Particle Tracer Explorers solar wind ion releases. The results indicate that the shocklike noise can be generated by two instabilities, an ion-electron instability that occurs for waves propagating parallel to the solar wind velocity and an ion-ion instability that occurs for waves propagating at a large angle to the solar wind direction. Both instabilities give high growth rates for both the lithium and barium releases. The calculated results agree with the observed ones in all main features. In the earlier stage of the ion cloud expansion, both instabilities are likely to occur, while in the later stage the ion-ion instability is more likely to occur.

Ma, T. Z.↗
NASA NTRS1987

A study of the feasibility of using sea and wind information from the ERS-1 satellite. Part 1: Wind scatterometer data

The use of scatterometer and altimeter data in wind and wave assimilation, and the benefits this offers for quality assurance and validation of ERS-1 data were examined. Real time use of ERS-1 data was simulated through assimilation of Seasat scatterometer data. The potential for quality assurance and validation is demonstrated by documenting a series of substantial problems with the scatterometer data, which are known but took years to establish, or are new. A data impact study, and an analysis of the performance of ambiguity removal algorithms on real and simulated data were conducted. The impact of the data on analyses and forecasts is large in the Southern Hemisphere, generally small in the Northern Hemisphere, and occasionally large in the Tropics. Tests with simulated data give more optimistic results than tests with real data. Errors in ambiguity removal results occur in clusters. The probabilities which can be calculated for the ambiguous wind directions on ERS-1 contain more information than is given by a simple ranking of the directions.

Anderson, D.↗
NASA NTRS1987

The magnetosphere of Uranus

The Voyager 2 encounter with Uranus on January 24, 1986, is described. It is noted that the combination of the orientation of the Uranian rotation axis with respect to the solar wind direction, and of the Uranian magnetic dipole axis with respect to the rotation axis, is a unique circumstance in the solar system. The Uranian magnetosphere is neither convection-dominated nor corotation-dominated, but rather a unique combination of both.

Belcher, J. W.↗
NASA NTRS1987

Remote sensing observations of sand movement in the Bahariya Depression, Western Egypt

Aerial photographs taken in the 1940's have been used in combination with recent Landsat MSS and TM data to study dune movement in the Western Desert of Egypt. The El-Ghorabi dunes track northwest to southeast along the eastern edge of the Bahariya Depression. These dunes are of complex longitudinal form with well-defined, lag-covered interdune corridors. Studies using both aerial coverage and multitemporal MSS and TM image data reveal little or no net southward extension or movement of the seifs, although field measurements and remote sensing data indicate small-scale lateral migration of dune crests and interdune corridors through time. The primary process of sand transport for these dunes seems to be in response to seasonal shifts in dominant wind direction, as reflected in the development and rapid response of sand shadows leeward of the main dune masses.

Maxwell, Ted A.↗
NASA NTRS1991

Atmospheric turbulence review of space shuttle launches

Research and analysis on the identification of turbulent regions from the surface to 16 km during Space Shuttle launches are discussed. It was demonstrated that the results from the FPS-16 radar/jimsphere balloon system in measuring winds can indeed indicate the presence or conditions ripe for turbulence in the troposphere and lower stratosphere. It was further demonstrated that atmospheric data obtained during the shuttle launches by the rawinsonde in conjunction with the jimsphere provides the necessary meteorological data to compute aerodynamic parameters to identify turbulence, such as Reynolds number drag coefficient, turbulent stresses, total energy, stability parameter, vertical gradient of kinetic energy, Richardson number, and the turbulence probability index. Enhanced temperature lapse rates and inversion rates, strong vector wind shears, and large changes in wind direction identify the occurrence of turbulence at the troposphere. When any two of the above conditions occur simultaneously, a significant probability of turbulence can occur.

Susko, Michael↗
NASA NTRS1991

NASA/Ames Research Center DC-8 data system

In-flight facility data acquisition, distribution, and recording on the NASA Ames Research Center (ARC) DC-8 are performed by the Data Acquisition and Distribution System (DADS). Navigational and environmental data collected by the DADS are converted to engineering units and distributed real-time to investigator stations once per second. Selected engineering units data are printed and displayed on closed circuit television monitors throughout flights. An in-flight graphical display of the DC-8 flight track (with barbs indicating wind direction and magnitude) has recently been added to the DADS capabilities. Logging of data run starts/stops and commentary from the mission director are also provided. All data are recorded to hard disk in-flight and archived to tape medium post-flight. Post-flight, hard copies of the track map and mission director's log are created by the DADS. The DADS is a distributed system consisting of a data subsystem, an Avionic Serial Data-to-VMEbus (ASD2VME) subsystem, and a host subsystem. Each subsystem has a dedicated central processing unit (CPU) and is capable of stand-alone operation. All three subsystems are housed in a single 20-slot VME chassis and communicate with each other over the VMEbus. The data and host subsystems are briefly discussed, and the DC-8 DADS internal configuration and system block diagram are presented.

Cherniss, S. C.↗
NASA NTRS1991

Terrestrial polarization imagery obtained from the Space Shuttle - Characterization and interpretation

An experiment to measure the polarization of land, sea, haze, and cloud areas from space was carried aboard the Space Shuttle in September 1985. Digitized polarimetric and photometric imagery in mutually perpendicular planes was derived in the red, green, and blue spectral regions from photographs taken with two synchronized Hasselblad cameras using type 5036 Ektachrome film. Digitization at the NASA Houston Video Digital Analysis Systems Laboratory permitted reduction of the imagery into equipolarimetric contours with a relative accuracy of + or - 20 percent for comparison to ground truth. The Island of Hawaii and adjacent sea and cloud areas were the objects of the specific imagery analyzed. Results show that cloud development is uniquely characterized using percent polarization without requiring precision photometric calibration. Furthermore, sea state and wind direction over the sea could be inferred as well as terrestrial soil texture.

Egan, Walter G.↗