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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Nonlinear seismic analysis of a reactor structure impact between core components

The seismic analysis of the FFTF-PIOTA (Fast Flux Test Facility-Postirradiation Open Test Assembly), subjected to a horizontal DBE (Design Base Earthquake) is presented. The PIOTA is the first in a set of open test assemblies to be designed for the FFTF. Employing the direct method of transient analysis, the governing differential equations describing the motion of the system are set up directly and are implicitly integrated numerically in time. A simple lumped-nass beam model of the FFTF which includes small clearances between core components is used as a "driver" for a fine mesh model of the PIOTA. The nonlinear forces due to the impact of the core components and their effect on the PIOTA are computed.

Hill, R. G.↗
NASA NTRS1976

Reliability of hybrid microcircuit bonding

Microcircuit failure due to differential thermal expansion depends on technique used to mount components to substrate. Effects of differential thermal expansion on ceramic chip capacitors are investigated for various bonding techniques.

Caruso, S. V.↗
NASA NTRS1977

Aerodynamic characteristics at Mach 6 of a hypersonic research airplane concept having a 70 deg swept delta wing

The hypersonic aerodynamic characteristics of an air-launched, delta-wing research aircraft concept were investigated at Mach 6. The effect of various components such as nose shape, wing camber, wing location, center vertical tail, wing tip fins, forward delta wing, engine nacelle, and speed brakes was also studied. Tests were conducted with a 0.021 scale model at a Reynolds number, based on model length, of 10.5 million and over an angel of attack range from -4 deg to 20 deg. Results show that most configurations with a center vertical tail have static longitudinal stability at trim, static directional stability at angles of attack up to 12 deg, and static lateral stability throughout the angle of attack range. Configurations with wing tip fins generally have static longitudinal stability at trim, have lateral stability at angles of attack above 8 deg, and are directionally unstable over the angle of attack range.

Clark, L. E.↗
NASA NTRS1977

The effects of the geosynchronous energetic particle radiation environment on spacecraft charging phenomena

The energetic electron environment at the geosynchronous orbit is responsible for a variety of adverse charging effects on spacecraft components. The most serious of these is the degradation and failure of a complementary-metal-oxide-semiconductor (CMOS) electronic components as a result of internal charge-buildup induced by the energetic electrons. Efforts to accurately determine the expected lifetime of these components in this orbit are hampered by the lack of detailed knowledge of the electron spectrum and intensity, particularly of the more penetrating energies greater than 1.5 MeV. This problem is illustrated through the calculation of the dose received by a CMOS device from the energetic electrons and associated bremsstrahlung as a function of aluminum shielding thickness using the NASA AE-6 and the Aerospace measured electron environments. Two computational codes which were found to be in good agreement were used to perform the calculations. For a given shielding thickness the dose received with the two radiation environments differ by as much as a factor of seven with a corresponding variation in lifetime of the CMOS.

Reagan, J. B.↗
NASA NTRS1978

On the average configuration of the geomagnetic tail

Over 3000 hours of IMP-6 magnetic field data obtained between 20 and 33 R sub E in the geomagnetic tail have been used in a statistical study of the tail configuration. A distribution of 2.5 minute averages of B sub Z as a function of position across the tail reveals that more flux crosses the equatorial plane near the dawn and dusk flanks than near midnight. The tail field projected in the solar magnetospheric equatorial plane deviates from the X axis due to flaring and solar wind aberration by an angle alpha = -0.9 y sub SM - 1.7 where Y sub SM is in earth radii and alpha is in degrees. After removing these effects the Y component of the tail field is found to depend on interplanetary sector structure. During an away sector the B sub Y component of the tail field is on average 0.5 gamma greater than that during a toward sector, a result that is true in both tail lobes and is independent of location across the tail.

Fairfield, D. H.↗
NASA NTRS1978

Interior noise studies for general aviation types of aircraft. I - Field studies. II - Laboratory studies

Sources of the interior noise level of typical light aircraft are identified for stationary conditions on the ground and in flight. In addition, the relationship between the exterior near- and far-field noise around an aircraft and the interior noise field is examined. The sound transmission paths of a light aircraft fuselage are investigated, and the relative effectiveness of several components of the fuselage for sound attenuation is assessed. The fuselage furnishes an acoustic attenuation of about 20 dB; windows and metallic areas appear to transmit approximately equal amounts of sound energy.

Jha, S. K.↗
NASA NTRS1980

Satellite Power Systems (SPS) concept definition study. Volume 5: Special emphasis studies

Satellite configurations based on the Satellite Power System baseline requirements were analyzed and a preferred concept selected. A satellite construction base was defined, precursor operations incident to establishment of orbital support facilities identified, and the satellite construction sequence and procedures developed. Rectenna construction requirement were also addressed. Mass flow to orbit requirements were revised and traffic models established based on construction of 60 instead of 120 satellites. Analyses were conducted to determine satellite control, resources, manufacturing, and propellant requirements. The impact of the laser beam used for space-to-Earth power transmission upon the intervening atmosphere was examined as well as the inverse effect. The significant space environments and their effects on spacecraft components were investigated to define the design and operational limits imposed by the environments on an orbit transfer vehicle. The results show that LEO altitude 300 nmi and transfer orbit duration 6 months are preferrable.

Hanley, G. M.↗
NASA NTRS1980

Effects of the Shuttle Orbiter fuselage and elevon on the molecular distribution of water vapor from the flash evaporator system

A concern has arisen regarding the emissive distribution of water molecules from the shuttle orbiter flash evaporator system (FES). The role of the orbiter fuselage and elevon in affecting molecular scattering distributions was nuclear. The effect of these components were evaluated. Molecular distributions of the water vapor effluents from the FE were measured. These data were compared with analytically predicted values and the resulting implications were calculated.

Richmond, R. G.↗
NASA NTRS1979

Theoretical analysis of an augmentor wing for a VTOL fighter

A method based on potential flow theory was developed for predicting forces and moments acting on augmentor wings for prescribed ejector jet characteristics. A three dimensional nonplanar vortex lattice is laid out on the chordal planes of the augmentor wing components. Jet induced effects are included in the boundary condition from which the horseshoe vortex strengths are obtained. The jet within the diffusor is made to expand from the primary nozzles to the diffusor exit and is represented by a distribution of vorticity on the jet boundary to provide proper entrainment. The jet downstream of the diffusor exit is modeled by a vorticity distribution and blockage panels and its centerline location and spreading rate are taken from experimental data. The vortex lattice and jet models are used in an iterative manner until the predicted diffusor exit velocity matches the specified one. Some comparisons with available data show good agreement at lower power settings.

Dillenius, M. F. E.↗
NASA NTRS1980

A survey of space radiation effects

The effects of space radiation and its significance for space missions, as they increase in scope, duration, and complexity are discussed. Type of radiation hazard may depend on location or on special equipment used. It is emphasized that it is necessary to search for potential radiation problems in the design stage of a mission. Problem areas such as radiation damage to solar cells and the revolutionary advances are discussed. Radiation effect to electronics components other than solar cells, and several specialized areas such as radioactivity and luminescence are also examined.

Hill, C. W.↗
NASA NTRS1980

On krypton isotopic abundances in the sun and in the solar wind

The Kr isotopic systematics in the meteorite Pesyanoe which is known to contain solar-type gases, are reported. Discrepancies in the isotopic data of fractions released at stepwise increasing temperatures cannot be reconciled with spallation Kr components, although spallation effects are significant. Fractionation mechanisms on the parent body and in the solar wind source region are considered and the implications for solar abundances discussed.

Marti, K.↗
NASA NTRS1982

CIRSS vertical data integration, San Bernardino study

The creation and use of a vertically integrated data base, including LANDSAT data, for local planning purposes in a portion of San Bernardino County, California are described. The project illustrates that a vertically integrated approach can benefit local users, can be used to identify and rectify discrepancies in various data sources, and that the LANDSAT component can be effectively used to identify change, perform initial capability/suitability modeling, update existing data, and refine existing data in a geographic information system. Local analyses were developed which produced data of value to planners in the San Bernardino County Planning Department and the San Bernardino National Forest staff.

Hodson, W.↗
NASA NTRS1979

Evaluation of SLAR and thematic mapper MSS data for forest cover mapping using computer-aided analysis techniques

The spatial characteristics of the data were evaluated. A program was developed to reduce the spatial distortions resulting from variable viewing distance, and geometrically adjusted data sets were generated. The potential need for some level of radiometric adjustment was evidenced by an along track band of high reflectance across different cover types in the Varian imagery. A multiple regression analysis was employed to explore the viewing angle effect on measured reflectance. Areas in the data set which appeared to have no across track stratification of cover type were identified. A program was developed which computed the average reflectance by column for each channel, over all of the scan lines in the designated areas. A regression analysis was then run using the first, second, and third degree polynomials, for each channel. An atmospheric effect as a component of the viewing angle source of variance is discussed. Cover type maps were completed and training and test field selection was initiated.

Hoffer, R. M.↗
NASA NTRS1983

Potential of minicomputer/array-processor system for nonlinear finite-element analysis

The potential of using a minicomputer/array-processor system for the efficient solution of large-scale, nonlinear, finite-element problems is studied. A Prime 750 is used as the host computer, and a software simulator residing on the Prime is employed to assess the performance of the Floating Point Systems AP-120B array processor. Major hardware characteristics of the system such as virtual memory and parallel and pipeline processing are reviewed, and the interplay between various hardware components is examined. Effective use of the minicomputer/array-processor system for nonlinear analysis requires the following: (1) proper selection of the computational procedure and the capability to vectorize the numerical algorithms; (2) reduction of input-output operations; and (3) overlapping host and array-processor operations. A detailed discussion is given of techniques to accomplish each of these tasks. Two benchmark problems with 1715 and 3230 degrees of freedom, respectively, are selected to measure the anticipated gain in speed obtained by using the proposed algorithms on the array processor.

Strohkorb, G. A.↗
NASA NTRS1983

Steady-state and dynamic evaluation of the electric propulsion system test bed vehicle on a road load simulator

The propulsion system of the Lewis Research Center's electric propulsion system test bed vehicle was tested on the road load simulator under the DOE Electric and Hybrid Vehicle Program. This propulsion system, consisting of a series-wound dc motor controlled by an infinitely variable SCR chopper and an 84-V battery pack, is typical of those used in electric vehicles made in 1976. Steady-state tests were conducted over a wide range of differential output torques and vehicle speeds. Efficiencies of all of the components were determined. Effects of temperature and voltage variations on the motor and the effect of voltage changes on the controller were examined. Energy consumption and energy efficiency for the system were determined over the B and C driving schedules of the SAE J227a test procedure.

Dustin, M. O.↗
NASA NTRS1983

Number and placement of control system sensors considering possible failures

A methodology has been presented which is intended to assist the designer of a control system for a large space structure to decide how many sensors should be incorporated in the system and where they should be placed on the structure. This approach is intended to be especially useful in the early stages of the evolution of the system, before a complete control system concept has been defined. This methodology is based on a quantitative measure of the observability of the system for a given set of sensors. The effect of possible component failures during the mission period was incorporated in the measure. The question of sensor placement is then resolved by finding the locations which maximize the performance measure. The number of components to use cannot be determined by optimizing the measure because the observability always improves with increased number of sensors if they are optimally located. However, the improvement in the measure with component number can be determined, and this information can be used along with data on cost, power required, etc., to decide how many sensors to use.

Vandervelde, W. E.↗
NASA NTRS1982

Unsteady Newton-Busemann flow theory. III - Frequency dependence and indicial response

Hui and Tobak applied the complete unsteady Newton-Busemann flow theory to the study of dynamic stability of oscillating aerofoils and bodies in revolution. The present article extends the results to general frequencies that may be applicable to flutter analysis. The results are likewise applied to the indicial response fluctuations in unsteady flow at very high Mach numbers. The study shows that for a group of body shapes in Newtonian flow (including the cone and wedge), the aerodynamic response to a step change in angle of attack or pitching velocity contains an initial-instant impulse followed by a rapid adjustment to the new steady-flow conditions. The impulse component is in effect an apparent mass term analogous to that which occurs initially in the aerodynamic indicial response at the zero Mach number limit.

Hui, W. H.↗