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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

X-ray electron study of lunar regolith from the Sea of Fertility and the Sea of Tranquillity

X-ray electron spectra were obtained of the 2p-levels of Fe, Ti, Si, Al, and Mg, and of the 1s-level in lunar regolith from the Sea of Fertility and the Sea of Tranquillity. The spectra of the same elements were recorded for approximately 30 rock forming minerals, oceanic gabbro, meteoritic eucrite, and several iron meteorites. Analysis of the results based on line positions showed that all the elements studied have the usual degrees of oxidation, and that oxygen atoms are their nearest neighbors. The predominant coordination number of Al is 4. Analysis and comparison of the Fe2p spectra in regolith, various iron meteorites, and stainless steel leads to these conclusions: Metallic iron in lunar regolith is in a highly dispersed state and is unusually stable with respect to oxidation by the oxygen of the earth's atmosphere.

Vinogradov, A. P.↗
NASA NTRS1974

Investigation of space shuttle launch vehicle external tank nose configuration effects (model 67-OTS) in the Rockwell International 7 by 7 foot trisonic wind tunnel (IA69)

Wind tunnel aerodynamic investigations were conducted on an 0.015-scale representation of the space shuttle launch configuration. The primary test objectives were to investigate shock wave formation and record the aerodynamic stability and control effects generated by a new external tank nose configuration (MCR 467) at a Mach number of 1.2. Schlieren photographs were taken at angles of attack of -4 deg, 0 deg, and 4 deg, beta = 0 deg with force and pressure data recorded over the alpha range of -4 deg equal to or less than alpha equal to or less than 4 deg at beta = + or - 4 deg. The launch configuration model, consisting of the VL70-00014OA/B Orbiter, the VL78-000041B ET, and the VL77-000036A SRBs, was sting mounted on a 2.5-inch Task type internal balance entering through the ET base region. Wing, body, and base pressure lines for all orifices were routed internally through the model to the sting support system. Parametric variation consisted only of altering the ET nose configuration.

Mennell, R.↗
NASA NTRS1977

Assembly and testing of a 1.8 by 3.7 meter Fresnel lens solar concentrator

A project was initiated to establish a technical data base on line focusing acrylic Fresnel lenses for use in a solar collector system that could generate temperatures in the range of 200 C to 370 C. The effort was originally directed toward electric power generation in the 100 to 10,000 kWe range using a distributed collector approach. However, as the program progressed, it centered on the development of a concentrator/collector subsystem concept that could meet the general requirement of thermal delivery within the 200 C to 370 C range. The expanded list of possible applications includes commercial heating/cooling and industrial process heat as well as electric power generation.

Robertson, J. E.↗
NASA NTRS1982

Data and data retrieval in space astronomy

To illustrate the range of storage and retrieval facilities and data products that are involved in space astronomy, the present situation on data from some instruments on the following missions is presented: Small Astronomy Satellite-B, Orbiting Astronomical Observatory 3, High Energy Astrophysics Observatory 2, International Ultraviolet Explorer, Viking Orbiter, and Solar Maximum Mission. In addition, the Coordinated Data Analysis Workshops conducted at the National Space Science Data Center are outlined to demonstrate the usefulness of building a problem-oriented on-line data base from instruments flown on a number of spacecraft and operating from ground-based facilities.

Vette, J. I.↗
NASA NTRS1985

Possible seasonal variability of mesospheric water vapor

Ground-based spectral line measurements of the 22.2 GHz water vapor line in atmospheric emission were made at the Jet Propulsion Laboratory, which have been used to deduce the mesospheric water vapor profile. The measurements were made nearly continuously in the spring and early summer of 1984. The results indicate a temporal increase in the water vapor mixing ratio in the upper mesosphere from April through June. At 75 km, this increase is nearly by a factor of 2. Comparison of the present results with the results of a similar series of measurements made at the Haystack (radio astronomy) Observatory indicate that this temporal increase is part of a seasonal variation.

Bevilacqua, R. M.↗
NASA NTRS1985

Ayres' bifurcated solar model

The assumptions of Ayres' model of the upper solar atmosphere are examined. It is found that the bistable character of his model is postulated - through the assumptions concerning the opacity sources and the effect of mechanical waves, which are allowed to destroy the CO molecules but not to heat the gas. The neglect of cooling by metal lines is based on their reduced local cooling rate, but it ignores the increased depth over which this cooling occurs. Thus, the bifurcated model of the upper solar atmosphere consists of two models, one cold at the temperature minimum, with a kinetic temperature of 2900 K, and the other hot, with a temperature of 4900 K.

Kalkofen, W.↗
NASA NTRS1986

The effects of electron scattering opacity in the broad emission-line regions of quasars

It is demonstrated that three observational puzzles in quasars, nearly symmetric Lyman-alpha profiles, weakly asymmetric C IV 1549 A, and offsets between the peaks of these high ionization lines and the systematic velocity, can all be explained by the standard model of the physical state of the broad-line region with the addition of the simplest possible kinematics. Electron scattering in the intercloud medium is the essential ingredient that had been previously neglected. It is shown that the profiles depend at least as sensitively on the run of physical conditions as on the velocity law. Approximate analytic representations of the line emissivities based on detailed photoionization models are used to describe that dependence.

Kallman, T. R.↗
NASA NTRS1987

Radiation heat transfer shapefactors for combustion systems

The computation of radiation heat transfer through absorbing media is commonly done through the zoning method which relies upon values of the geometric mean transmittance and absorptance. The computation of these values is difficult and expensive, particularly if many spectral bands are used. This paper describes the extension of a scan line algorithm, based upon surface-surface radiation, to the computation of surface-gas and gas-gas radiation transmittances.

Emery, A. F.↗
NASA NTRS1989

An adaptive implicit/explicit finite element scheme for compressible viscous high speed flow

An adaptive implicit/explicit finite element procedure for the solution of three-dimensional problems of steady compressible viscous high-speed flows is presented. In the vicinity of solid walls, a grid-exhibiting structure in the normal direction is employed, while away from this region the grid is totally unstructured. The implicit form of the algorithm is used near solid walls, with the grid structure being utilized in an equation solution approach based upon line relaxation. The explicit form of the algorithm is used elsewhere. Grid adaptation is achieved by means of adaptive remeshing. To illustrate the performance of the proposed method, solutions are obtained for the problems of shock-boundary layer interaction and shock-shock interaction on a swept cylindrical leading edge. Comparisons are made with experimental observations.

Hassan, O.↗
NASA NTRS1989

The simulation of 2D compressible viscous high speed flow by the finite element method

Am implicit/explicit procedure for the solution of problems of two-dimensional steady compressible viscous high-speed flows is presented. In the vicinity of solid walls, a grid which need only exhibit structure in the normal direction is employed while, away from this region, the grid is totally unstructured. The implicit form of the algorithm is used near solid walls, with the grid structure being utilized in an equation solution approach, based upon line relaxation. The explicit form of the algorithm is used elsewhere. Grid adaptation is achieved by means of adaptive remeshing. To illustrate the performance of the proposed method, problems of shock-boundary layer interaction and flow over a simulated forebody at high Mach number are included.

Hassan, O.↗
NASA NTRS1990

[NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 1:] The value of Scientific and Technical Information (STI), its relationship to Research and Development (R&D), and its use by US aerospace engineers and scientists

The relationship between scientific and technical information (STI), its use by aerospace engineers and scientists, and the aerospace R&D process is examined. Data are presented from studies of the role of STI in the performance and management of R&D activities and the behavior of engineers when using and seeking information. Consideration is given to the information sources used to solve technical problems, the production and use of technical communications, and the use of libraries, technical information centers, and on-line data bases.

Pinelli, Thomas E.↗
NASA NTRS1990

Enhanced thermochemical nonequilibrium computations of flow around the aeroassist flight experiment vehicle

A three-dimensional explicit, finite-rate, shock-capturing numerical algorithm is used to calculate thermochemical nonequilibrium flowfields about the Aeroassist Flight Experiment vehicle at one of its flight trajectory points. The full Navier-Stokes equations and an eleven species chemical model with the latest reaction rates are incorporated into the code. Results are compared against experimental data and other numerical solutions. The effects of changes to the physical model on the stagnation line and base region flow and surface quantities on the forebody are investigated.

Palmer, Grant↗
NASA NTRS1990

Simple model of plasma acceleration in a magnetic nozzle

A collisionless, steady-state, cold-plasma model is used to calculate the three-dimensional trajectory of a plasma as it is accelerated through a diverging magnetic field. The magnetic field is assumed to be axisymmetric with nonzero radial and axial components and zero azimuthal component. Although random thermal motion of plasma species is neglected in the cold plasma approximation, an important effect of plasma thermal energy is accounted for in the model as the kinetic energy of electrons in their Larmor motion about magnetic field lines. Calculations based on this model confirm previous studies which suggested that plasma separation from the field of a magnetic nozzle can take place even in the absence of collisional diffusion. It is shown that plasma divergence in a magnetic nozzle can be controlled by tailoring the field geometry.

Sercel, Joel C.↗
NASA NTRS1991

Determination of absolute strengths of N2 quadrupole lines from high-resolution ground-based IR solar observations

The strength of S-branch lines of the N2 (1-0) electric quadrupole vibration-rotation band are determined by an analysis of solar absorption spectra. The solar data were recorded with a Fourier transform spectrometer and are characterized by high resolution, and a high signal-to-noise ratio. By extrapolating equivalent width measurements of the lines from varying air masses to zero air mass, the line strengths are found for the transitions from S7 to S10. The results presented do not include half widths and are found to be accurate to within 5 percent, and following a redetermination the N2 transitions are accurate to within 0.0002/cm. Line-of-sight atmospheric air masses associated with remotely sensed IR spectroscopic observations can be determined directly by utilizing the highly accurate data.

Demoulin, P.↗
NASA NTRS1991

A far wing line shape theory and its application to the water continuum absorption in the infrared region. I

The present theory for the continuous absorption that is due to the far-wing contribution of allowed lines is based on the quasistatic approximation for the far wing limit and the binary collision approximation of one absorber molecule and one bath molecule. The validity of the theory is discussed, and numerical results of the water-continuum absorption in the IR region are presented for comparison with experimental data. Good agreement is obtained for both the magnitude and temperature dependence of the absorption coefficients.

Ma, Q.↗
NASA NTRS1991

Recent advances in the development and transfer of machine vision technologies for space

Recent work concerned with real-time machine vision is briefly reviewed. This work includes methodologies and techniques for optimal illumination, shape-from-shading of general (non-Lambertian) 3D surfaces, laser vision devices and technology, high level vision, sensor fusion, real-time computing, artificial neural network design and use, and motion estimation. Two new methods that are currently being developed for object recognition in clutter and for 3D attitude tracking based on line correspondence are discussed.

Defigueiredo, Rui J. P.↗
NASA NTRS1993

NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 16: A comparison of the technical communications practices of Russian and US aerospace engineers and scientists

As part of Phase 4 of the NASA/DOD Aerospace Knowledge Diffusion Project, two studies were conducted that investigated the technical communications practices of Russian and U.S. aerospace engineers and scientists. Both studies have the same five objectives: first, to solicit the opinions of aerospace engineers and scientists regarding the importance of technical communications to their profession; second, to determine the use and production of technical communications by aerospace engineers and scientists; third, to seek their views about the appropriate content of an undergraduate course in technical communications; fourth, to determine aerospace engineers' and scientists' use of libraries, technical information centers, and on-line data bases; and fifth, to determine the use and importance of computer and information technology to them. A self-administered questionnaire was distributed to aerospace engineers and scientists at the Central Aero-Hydrodynamic Institute (TsAGI), NASA ARC, and NASA LaRC. The completion rates for the Russian and U.S. surveys were 64 and 61 percent, respectively. The responses of the Russian and U.S. participants, to selected questions, are presented in this report.

Thomas E Pinelli↗
NASA NTRS1993

Multigrid methods for numerical simulation of laminar diffusion flames

This paper documents the result of a computational study of multigrid methods for numerical simulation of 2D diffusion flames. The focus is on a simplified combustion model, which is assumed to be a single step, infinitely fast and irreversible chemical reaction with five species (C3H8, O2, N2, CO2 and H2O). A fully-implicit second-order hybrid scheme is developed on a staggered grid, which is stretched in the streamwise coordinate direction. A full approximation multigrid scheme (FAS) based on line distributive relaxation is developed as a fast solver for the algebraic equations arising at each time step. Convergence of the process for the simplified model problem is more than two-orders of magnitude faster than other iterative methods, and the computational results show good grid convergence, with second-order accuracy, as well as qualitatively agreement with the results of other researchers.

Liu, C.↗