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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Development and fabrication of an advanced liquid cooling garment

A tube/fin concept liquid cooling garment head cooler was developed, fabricated and delivered to NASA-ARC. The head cooler was fabricated from polyurethane film which sandwiches the transport fluid tubing and a thermally conductive fin material. The head cooler garment is sewn to form a skull cap and covered with a comfort liner. In addition, two Neonate heating garments were fabricated and supplied to NASA for further finishing and use in medical tests. The resulting garment is flexible, elastic and conforms to the head comfortably. Tests on a tube/fin element of identical construction as the head cooler demonstrated good thermal effectiveness. Use of commercially available materials and development of relatively simple fabrication techniques give the potential for a low garment cost.

Hixon, C. W.↗
NASA NTRS1981

Thermionic Energy Conversion (TEC) topping thermoelectrics

Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.

Morris, J. F.↗
NASA NTRS1981

Laser velocimetry technique applied to the Langley 0.3 meter transonic cryogenic tunnel

A low power laser velocimeter operating in the forward scatter mode was used to measure free stream mean velocities in the Langley 0.3 Meter Transonic Cryogenic Tunnel. Velocity ranging from 51 to 235 m/s was measured. Measurements were obtained for a variety of nominal tunnel conditions: Mach numbers from 0.20 to 0.77, total temperatures from 100 to 250 K, and pressures from 101 to 152 kPa. Particles were not injected to augment the existing Mie scattering materials. Liquid nitrogen droplets were the existing liqht scattering material. Tunnel vibrations and thermal effects had no detrimental effects on the optical system.

Gartrell, L. R.↗
NASA NTRS1980

Thermal Pollution Mathematical Model. Volume 5: User's Manual for Three-Dimensional Rigid-Lid Model

A user's manual for a three dimensional, rigid lid model used for hydrothermal predictions of closed basins subjected to a heated discharge together with various other inflows and outflows is presented. The model has the capability to predict (1) wind driven circulation; (2) the circulation caused by inflows and outflows to the domain; and (3) the thermal effects in the domain, and to combine the above processes. The calibration procedure consists of comparing ground truth corrected airborne radiometer data with surface isotherms predicted by the model. The model was verified for accuracy at various sites and results are found to be fairly accurate in all verification runs.

Lee, S. S.↗
NASA NTRS1980

Exploratory models of the earth's thermal regime during segregation of the core

Some simple exploratory theoretical models of the thermal effects of core segregation have been investigated, assuming an initially homogeneous earth and including convective heat transport through a 'parameterized convection' approximation. The results indicate that either (1) mantle temperatures 30% or more above present values may have resulted from the gravitational energy released during core segregation, (2) the earth retained very little of its accretional energy, (3) core segregation lasted for one billion years or more, or (4) the earth accreted heterogeneously. Option 3 seems to be precluded by terrestrial lead isotope data, and the alternatives each raise substantial questions concerning the mechanics, chemistry, and petrology of the earth's early history. There is no recognized evidence for the early hot phase of option 1, and option 4 implies, among other things, an analogous early hot phase. Although it has not been favored, option 2 may be viable.

Davies, G. F.↗
NASA NTRS1980

Ultraviolet /UV/ emission line mapping of selected regions in the Orion Nebula

Digital processing of data from the International Ultraviolet Explorer (IUE) satellite are used to obtain monochromatic mosaic images of the most prominent UV spectra lines at 35 locations in the central region of the Orion Nebula. The image processing techniques include calculations of the spectrograph orientation and the thermal effects, normalization for exposure time, background subtraction, correction for sensitivity variation within the IUE spectrograph aperture, correction to an absolute flux scale, sample interpolation, and display on graphic devices. The resulting UV emission line intensity maps may be used in conjunction with observations of other wavelength regions to determine the spatial distribution of ionization and abundance levels of carbon and oxygen in Orion.

Turnrose, B. E.↗
NASA NTRS1981

Submillisecond measurements of system optical modulation functions in mosaic focal plane arrays

Measurements of system optical modulation functions (MTF, SWR) may be distorted by time-dependent environmental effects (thermal, vibration, flexure) and by electronics drift. Fast data collection may therefore be advantageous by minimizing drift time. The problem of fast data collection is accentuated when modulation data must be taken on a large number of detectors in a focal plane array. A method has been developed for the generation and storage of knife edge data from focal plane arrays, where data collection time per detector is in the submillisecond range. Once knife edge collects are completed, MTF response is found using conventional convolution techniques. SWR is obtained directly from knife edge response using a computerized simulation algorithm which bypasses use of MTF harmonics. Requirements for detector electronics speed, damping, and dynamic range are considered.

Thurlow, P. E.↗
NASA NTRS1981

The Space Shuttle

The development of the Space Shuttle is traced. Aerodynamic loads and dynamic characteristics, structural design, ascent and entry heating profiles, and propulsion systems are discussed. Problems in the area of systems management and flight control during entry and in the design of an effective thermal control system are discussed in detail.

Faget, M. A.↗
NASA NTRS1981

Short interval testing of solar cells

A drawback of conventional electrical evaluation procedures regarding solar cells is related to time consuming operations required in the determination of specific parameters, such as the maximum power point, from the plotted curves, and to the transfer of data to a large digital computer for analysis and manipulation. This is especially true when large numbers of cells must be measured. To overcome such drawbacks, a digital short interval tester was designed and constructed. The new tester provides rapid and accurate measurements at constant temperature. The utilization of a light shutter makes it possible to measure up to 200 data points along the I-V curve in less than a second, thus avoiding thermal effects. Because the system is digital, parameters such as the maximum power may be calculated directly from the data.

Saylor, C. R.↗
NASA NTRS1982

Turbofan forced mixer-nozzle internal flowfield. Volume 3: A computer code for 3-D mixing in axisymmetric nozzles

A finite difference method is developed for making detailed predictions of three dimensional subsonic turbulent flow in turbofan lobe mixers. The governing equations are solved by a forward-marching solution procedure which corrects an inviscid potential flow solution for viscous and thermal effects, secondary flows, total pressure distortion and losses, internal flow blockage and pressure drop. Test calculations for a turbulent coaxial jet flow verify that the turbulence model performs satisfactorily for this relatively simple flow. Lobe mixer flows are presented for two geometries typical of current mixer design. These calculations included both hot and cold flow conditions, and both matched and mismatched Mach number and total pressure in the fan and turbine streams.

Kreskovsky, J. P.↗
NASA NTRS1982

Cryopump for large pulses of hydrogen

A test involving a flow of hot hydrazine decomposition products at a rate of 13.6 g/s (0.03 lb/s) established the requirement to maintain pressure in an 11.9-m-(39 ft) diameter space chamber below 200 microns. The flow, 2/3 hydrogen and 1/3 nitrogen by volume, continued for several periods ranging from 3 to 15 min. The pressure requirement was necessary to minimize thermal effects of the gas on the test vehicle but was well beyond the capability of the existing facility pumps. Various methods of obtaining additional temporary jump capacity were considered. From these, the slugged-charcoal approach was selected as the quickest and least expensive method to implement.

Moore, B. C.↗
NASA NTRS1982

Heat flow control and segregation in directional solidification

Optimization of the vertical Bridgman technique for growth of electronic materials in single crystal form was investigated. The limitations of the crystal growth configuration were experimentally determined and heat transfer related deficiencies identified. Design of an alternate system was based on the use of heat pipes separated by a gradient region. Heat transfer analyses based on one and two dimensional models indicated the necessity of a flexible gradient zone configuration. Directional melting of binary systems as encountered during seeding in melt growth was analysed for concurrent compositional changes at the crystal-metal interface, and the theoretical treatment numerically applied to HgCdTe and Ga doped germanium. A theoretical and experimental study of the thermal effects associated with current flow was conducted. It was found that experimental measurements of dc induced growth during crystal pulling can be used for the precise determination of the Peltier coefficient.

Witt, A. F.↗
NASA NTRS1982

Structure of field rotating disturbances in warm plasma

A model in which thermal effects are simulated through use of a multibeam plasma distribution function is developed and investigated to see if solutions which take an initially uniform magnetized plasma to a new uniform state with different field orientation are possible. The momentum conservation integrals are found to admit two classes of such solutions, but only one class exhibits appropriate asymptotic behavior. Extensive numerical integrations have failed to demonstrate the existence of the desired solutions.

Wolfson, R.↗
NASA NTRS1981

Measurement of solar radius changes

Results of daily photometric measurements of the solar radius from Mt. Wilson over the past seven years are reported. Reduction of the full disk magnetograms yields a formal error of 0.1 arcsec in the boustrophedonic scans in the 5250.2 A FeI line. 150 scan lines comprise each observation; 1,412 observations were made from 1974-1981. Measurement procedures, determination of the scattered light of the optics and the atmosphere, and error calculations are described, noting that days of poor atmospheric visibility are omitted from the data. The horizontal diameter of the sun remains visually fixed while the vertical component changes due to atmospheric diffraction; error accounting for thermal effects, telescope aberrations, and instrument calibration are discussed, and results, within instrument accuracy, indicate no change in the solar radius over the last seven years.

Labonte, B. J.↗
NASA NTRS1982

Stability of ammonia in the primitive terrestrial atmosphere

The rate at which ammonia would have been destroyed in the earth's atmosphere under assumed NH3 mixing ratio conditions of 10 to the -8th to 0.0001 is calculated by a one-dimensional photochemical model, and the destruction rates are compared with possible biotic and abiotic ammonia sources. It is found that, while the mixing ratio of 10 to the -8th needed for the evolution of life could have been maintained by abiotic sources, the value of 0.00001 needed for the production of significant greenhouse warming could not have been sustained abiotically. The increase of atmospheric ammonia due to biological activities during the Archean is also considered lower than the level required for the generation of measurable thermal effects.

Kasting, J. F.↗
NASA NTRS1983

Large-area sheet task: Advanced dendritic-web-growth development

Thermally generated stresses in the growing web crystal were reduced. These stresses, which if too high cause the ribbon to degenerate, were reduced by a factor of three, resulting in the demonstrated growth of high-quality web crystals to widths of 5.4 cm. This progress was brought about chiefly by the application of thermal models to the development of low-stress growth configurations. A new temperature model was developed which can analyze the thermal effects of much more complex lid and top shield configurations than was possible with the old lumped shield model. Growth experiments which supplied input data such as actual shield temperature and melt levels were used to verify the modeling results. Desirable modifications in the melt level-sensing circuitry were made in the new experimental web growth furnace, and this furnace has been used to carry out growth experiments under steady-state conditions. New growth configurations were tested in long growth runs at Westinghouse AESD which produced wider, lower stress and higher quality web crystals than designs previously used.

Duncan, C. S.↗
NASA NTRS1983

Thermionic energy converters

The efficiency of thermionic energy converters is improved by internal distribution of tiny sorted cesium diodes driven by the thermal gradient between the primary emitter and the collector. The tiny, sorted diode distribution comprises protrusions of the emitter material from the main emitter face which contact the main collector face thermally but not electrically. The main collector ends of the protrusions are separated from the main collector by a thin layer of insulation, such as aluminum oxide. The shorted tiny diode distribution augments cesium ionization through internal thermal effects only within the main diode. No electrical inputs are required. This ionization enhancement by the distribution of the tiny shorted diodes not only reduces the plasma voltage drop but also increases the power output and efficiency of the overall thermionic energy converter.

Morris, J. F.↗
NASA NTRS1982

Electromagnetic cyclotron-loss-cone instability associated with weakly relativistic electrons

The amplification of fast extraordinary mode waves at frequencies very close to the electron cyclotron frequency, due to the presence of a population of energetic electrons with a loss-cone type distribution, is studied. Low-energy background electrons are included in the analysis. Two types of loss-cone distribution functions are considered, and it is found that the maximum growth rates for both distribution functions are of the same order of magnitude. When the thermal effects of the energetic electrons are included in the dispersion equation, the real frequencies of the waves are lower than those obtained by using the cold plasma approximation. This effect tends to enhance the growth rate. An idealized case including a parallel electric field such that the distribution function of the trapped energetic electrons is modified is also considered. It is assumed that the parallel electric field can remove the low-energy background electrons away from the source region of radiation. Both these effects increase the growth rate.

Wong, H. K.↗