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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Pressure distribution in a converging-diverging nozzle during two-phase choked flow of subcooled nitrogen

Choked flow rates and axial pressure distributions were measured for subcooled nitrogen in a converging-diverging nozzle with a constant area section in the throat region. Stagnation pressures ranged from slightly above saturation to twice the thermodynamic critical pressure. Stagnation temperatures ranged from 0.75 to 1.03 times the thermodynamic critical temperature. The choking plane appears to be at the divergence end of the constant area throat section. At high stagnation pressures the fluid appears to stay liquid well into the constant area throat region; however, at near saturation stagnation pressures it appears that vaporization occurs at or before the entrance to the constant area throat region. The throat-to-stagnation pressure ratio data exhibits an anomalous flat region. This anomaly appears to be fundamentally related to the two-phase process and not merely to the present specific nozzle geometry. The fluid appears to be metastably all liquid below the saturation pressure. The data are compared to various flow models. No model adequately describes the whole range of the experiment.

Simoneau, R. J.↗
NASA NTRS1976

A technique for accelerating iterative convergence in numerical integration, with application in transonic aerodynamics

A technique is described for the efficient numerical solution of nonlinear partial differential equations by rapid iteration. In particular, a special approach is described for applying the Aitken acceleration formula (a simple Pade approximant) for accelerating the iterative convergence. The method finds the most appropriate successive approximations, which are in a most nearly geometric sequence, for use in the Aitken formula. Simple examples are given to illustrate the use of the method. The method is then applied to the mixed elliptic-hyperbolic problem of steady, inviscid, transonic flow over an airfoil in a subsonic free stream.

Martin, E. D.↗
NASA NTRS1976

Total attenuation measurements of the Intertropical Convergence Zone by satellite altimeter

The 13.9-GHz radar altimeter operating aboard Skylab detected incidences of intense attenuation during a passage over the Intertropical Convergence Zone (ITCZ). The signal returned to the instrument from the surface was reduced by 4.5 and 6 dB over two distinct meteorological disturbances near 8 deg N, 27.5 deg W. Although it is impossible to deduce the vertical composition of the ITCZ cloud band from these data, the usefulness of the radar altimeter as a meteorological sensor of total atmospheric attenuation is demonstrated.

Parsons, C. L.↗
NASA NTRS1977

Limitations of the narrow-angle convergent pair

Spatial triangulations and topographies of the Martian surface derived from Viking Orbiter pictures depend on the use of symmetric narrow-angle convergent pairs. The overlap in each pair is close to 100 percent and the ground principal points virtually coincide. The analysis of this paper reveals a high degree of indeterminacy in such pairs and at least in part explains the rather disappointing precision of the associated spatial triangulations.

Arthur, D. W. G.↗
NASA NTRS1977

Moisture convergence from a combined mesoscale moisture analysis and wind field for 24 April 1975

Precipitable water values inferred from the Vertical Temperature Profile Radiometer data of the polar orbiting NOAA-4 satellite are used in conjunction with wind-field analyses obtained from Synchronous Meteorological Satellite visible-channel data to study the moisture convergence in the boundary layer immediately preceding a storm. This combination of data simulates the information that will be available from the Visible and Infrared Spin-Scan Radiometer on board the GOES-D satellite, which is scheduled to begin operation in the 1980s. Serviceable representations of boundary layer flow are developed through analysis of the satellite infrared cumulus velocities, although the flow representations are not exactly located in the vertical.

Negri, A. J.↗
NASA NTRS1979

The 1977 intertropical convergence zone experiment

Data are presented from the 1977 Intertropical Convergence Zone (ITCZ) Experiment conducted in the Panama Canal Zone in July 1977. Measurements were made daily over a 16-day period when the ITCZ moved across the Canal Zone. Two aircraft (Learjet and U-2) flew daily and provided data from horizontal traverses at several altitudes to 21.3 km of ozone, temperature, pressure, water vapor, aerosols, fluorocarbons, methane, nitrous oxide, nitric oxide, and nitric acid. Balloonsondes flown four times per day provided data on ozone, wind fields, pressure, temperature, and humidities to altitudes near 30 km. Rocketsondes provided daily data to altitudes near 69 km. Satellite photography provided detailed cloud information. Descriptions of individual experiments and detailed compilations of all results are provided.

Poppoff, I. G.↗
NASA NTRS1979

The intertropical convergence zone experiment: Background and summary

The Intertropical Convergence Zone Experiment (ITCZ) was the first in an anticipated series of observational programs designed to explore the nature and magnitude of troposphere-stratosphere exchange processes. The overall meteorological background and motivations for a measurement program in the ITCZ are summarized and the nature of the field experiments are briefly described.

Holton, J. R.↗
NASA NTRS1979

Notes on the meteorology of the intertropical convergence zone during the July 1977 experiment

The stratosphere and troposphere are large-scale open systems which exchange mass and trace constituents. If averaged over all longitudes, mass exchange can be expressed as products of the means and the mean of the product of the deviations from the mean. At high latitudes, the mass exchange is dominated by the deviations from the mean. At low latitudes, in the tropics, it is generally assumed that the mass exchange is caused by the mean motion. Figures are presented which depict: Northern Hemisphere mean motion; Convergence Zone motion; clouds and their motions; surface pressure variations; and meteorological parameters such as temperature, relative humidity, and ozone mixing ratios.

Danielson, E. F.↗
NASA NTRS1979

Balloon-borne ozonesonde and rocket temperature and wind data gathered during the July 1977 intertropical convergence zone experiment

In middle latitudes, it is possible for large concentrations of stratospheric air to be brought down to the tropopause through folds or breaks in the tropopause. The exchange of air from the tropopause into higher altitudes is not well understood. Thus, the ITCZ (Intertropical Convergence Zone) experiment, conducted from July 16 through July 31, 1977, included a series of balloon-borne ozone soundings. The results of these soundings are presented and explain in the vertical exchange of air and provide information on the short vertical scales-of-motion. Rocketsonde data was also gathered in the ITCZ experiment in support of a stratospheric scales-of-motion study. The investigation was to determine whether rocketsonde and satellite information currently used yield information on the stratospheric horizontal wave spectrum and its importance with respect to tropospheric and mesospheric interaction and transport.

Schmidlin, F. J.↗
NASA NTRS1979

Measurement of NO and O3 from aircraft: 1977 tropical convergence zone experiment

As part of the Ames Research Center program to explore the nature of stratosphere-troposphere exchange processes occurring in the Intertropical Convergence Zone, simultaneous in situ measurements of nitric oxide and ozone mixing ratios were made with the Ames stratospheric air sampler SAS 2. The SAS 2 is a second-generation system; it employs four parallel sensors and was designed primarily for measurements at altitudes of 60,000 ft and above on the U-2 stratospheric research aircraft. The only modifications required for this study was the addition of an air sample flow restrictor. Data were obtained with the SAS 2 system on July 26, 27, 30 and 31, 1977. Generally, 30-min measurements were made at each of six altitudes ranging from 45,000 ft to 70,000 ft, and separated by 5,000 ft intervals.

Starr, W. L.↗
NASA NTRS1979

Trace constituent mixing ratios in the lower stratosphere during the 1977 intertropical convergence zone experiment

Minor constituents in the atmosphere can play an important role as tracers in studies of atmospheric transport and mixing. Simultaneous measurements of the vertical distribution of trace constituents in the troposphere and lower stratosphere were conducted in the region of the Intertropical Convergence Zone (ITCZ). An effort was made to measure the mixing ratios of selected trace constituents. A cryogenic sampling system on board a U-2 aircraft was used to acquire whole-air samples and to cryogenically collect samples at 13.7 to 21.3 km. Simultaneous tropospheric measurements using whole-air sampling canisters on board a Learjet aircraft were also carried out.

Vedder, J. F.↗
NASA NTRS1979

Determination of trace gases in learjet and U-2 whole air samples collected during the intertropical convergence zone experiment

The contribution of Washington State University (WSU) to the Intertropical Convergence Zone (ITCZ) study, conducted in the Panama Canal Zone in July 1977 is reported. The ITCZ program had the objective to study the meteorology and air chemistry to determine, if possible, the magnitude of injection of tropospheric air into the stratosphere in the ITCZ. WSU was responsible for two phases of the air chemistry program for the ITCZ study: (1) the collection of whole-air samples from ground level to 13.7 km using a Learjet as a sampling platform, and the analysis of the samples for selected halocarbons, C2 hydrocarbons, N2O, and SF6; and (2) the analysis for selected halocarbon species and N2O of low pressure whole-air samples, collected between 13.7 km and 21.3 km by a U-2 aircraft. The report is divided into separate sections describing the Learjet and the U-2 sampling methods, analytical methods, and results. Complete data tables for all samples analyzed are given.

Cronn, D. R.↗
NASA NTRS1979

Intertropical convergence zone ozone profiles from the Learjet ozone analyzer

An ozone analyzer operated as part of the sampling package aboard the NASA Learjet on each flight in the Panama ITCZ (Intertropical Convergence Zone) experiment. The measurement program was not successful because of instrument failure, apparently due to high humidity effects on one or more components of the ozone sensing instrument. A brief description of the experimental installation and some comments about an apparent correlation between very low ozone concentrations and cloud layers at altitude are presented.

Robinson, E.↗
NASA NTRS1979

Preliminary results from the University of Denver infrared spectrometer - 1977 intertropical convergence zone experiment

The Denver University Infrared Spectrometer (DUIRS) is a liquid-helium-cooled emission radiometer designed to study minor atmospheric constituents. DUIRS flew on 12 data flights during the 1977 Intertropical Convergence Zone experiment. No data were obtained on the flight from Wallops Island to Panama because of a power failure or on the return flight to Wallops Island because of a cryogen line freeze-up. The data coverage on the nine vertical profile flights that were flown before the freeze-up are shown. Typical spectra and variations as a function of U-2 (research aircraft) altitude are also shown. Radio metric data and rawinsonde temperature data were used to perform band model calculations to obtain molecular number densities in the column above the aircraft at each altitude.

Barker, D. B.↗
NASA NTRS1979

Stratospheric aerosols in the intertropical convergence zone, Panama Canal zone

To investigate whether injection sources of the stratospheric aerosol layer could be detected in the tropical stratosphere, an examination of the aerosol vertical and horizontal size distribution around the Intertropical Convergence Zone (ITCZ) at the Panama Canal Zone was performed during the summer of 1977. By comparing these data with similar measurements in temperate and polar regions, it was hoped to discover variations in particle size that would indicate whether a young aerosol is forming and entering the stratosphere at the ITCZ; where the aerosol matures; and finally, where it reenters the troposphere. The methods used in the investigations and the results obtained from the analyses are described.

Farlow, N. H.↗
NASA NTRS1979

Airborne pressure and temperature measurements during the 1977 intertropical convergence zone experiment

During the 1977 ITCZ (Intertropical Convergence Zone) experiment in Panama two aircraft and numerous balloon-borne radiosonde instruments were equipped to measure pressure and temperature. The experiment was a coordinated effort to evaluate the meteorological conditions that prevailed from July 17 through 31, 1977. A critical analysis of the data collected on one of the aircraft (the Lear jet) operating at altitudes to 13,000 m for about 2 hr each day during most days of the experiment is presented. The discussion includes a comparison of the vertical profiles of potential temperature obtained from the Learjet with those obtained from balloons launched at Ft. Sherman. Time histories of pressure, temperature, and potential temperature, as observed from the Learjet are also presented.

Munoz, R. M.↗