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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 NTRS1978

A feasibility study of a diffusion barrier between Ni-Cr-Al coatings and nickel-based eutectic alloys

Coating systems have been proposed for potential use on eutectic alloy components in high-temperature gas turbine engines. In a study to prevent the deterioration of such systems by diffusion, a tungsten sheet 25 microns thick was placed between eutectic alloys and an Ni-Cr-Al layer. Layered test specimens were aged at 1100 C for as long as 500 h. Without the tungsten barrier the delta phase of the eutectic deteriorated by diffusion of niobium into the Ni-Cr-Al. Insertion of the tungsten barrier stopped the diffusion of niobium from the delta phase. Chromium diffusion from the Ni-Cr-Al into the gamma/gamma-prime phase of the eutectic was greatly reduced by the barrier. However, the barrier thickness decreased with time, and tungsten diffused into both the Ni-Cr-Al and the eutectic. When the delta platelets were aligned parallel rather than perpendicular to the Ni-Cr-Al layer, diffusion into the eutectic was reduced.

Young, S. G.↗
NASA NTRS1975

Experimental feasibility study of the application of magnetic suspension techniques to large-scale aerodynamic test facilities

Based on the premises that magnetic suspension techniques can play a useful role in large scale aerodynamic testing, and that superconductor technology offers the only practical hope for building large scale magnetic suspensions, an all-superconductor 3-component magnetic suspension and balance facility was built as a prototype and tested sucessfully. Quantitative extrapolations of design and performance characteristics of this prototype system to larger systems compatible with existing and planned high Reynolds number facilities at Langley Research Center were made and show that this experimental technique should be particularly attractive when used in conjunction with large cryogenic wind tunnels.

Zapata, R. N.↗
NASA NTRS1980

Feasibility studies for light scattering experiments to determine the velocity relaxation of small particles in a fluid

An approach for measuring the non-Markoffian component in the relaxation mechanism of a Brownian particle is proposed which combines desirable features of both the shock wave experiment and conventional light scattering experiments. It is suggested that the radiation pressure generated by a C.W. laser be used to guide an individual spherical particle to terminal velocity. At an appropriate time, the beam intensity is suddenly lowered to a value at which the radiation pressure is negligible, and the ensuing velocity relaxation is measured directly.

Acquista, C.↗
NASA NTRS1980

Ultimate intrinsic-coercivity samarium-cobalt magnet: An Earth-based feasibility study for space-shuttle missions

Techniques for containerless melting and solidification of the samarium-cobalt alloy without excessive oxidation were developed. The rationale for extending these experiments in a weightless environment is also discussed. The effect of oxygen content from 0.15 to 0.63 weight percent and grain size in the range of 2 to 10 micrometers has been examined on arc-plasma-sprayed SmCo5 magnets. Contrary to expectations, the larger grain sizes tended to improve the coercivities. This was attributed to an increase in homogeneity resulting from higher temperature treatments used to produce larger grain size. No significant differences in coercivity were observed on the basis of oxygen content in the range examined. It is expected that more meaningful data on the relationship between oxygen content and coercivity will be seen when the oxygen content can be lowered to less than 0.1 weight percent.

Das, D. K.↗
NASA NTRS1980

Thin n-i-p radiation-resistant solar cell feasibility study

Silicon solar cells were fabricated to verify the predictions that: (1) thin n(+)pp(+) cells can provide high values of open circuit voltage even when high resistivity base material ( 1000 omega-cm) is used; (2) cells with good p(+) back contacts will display an increase in open circuit voltage with decreasing cell thickness; and (3) high quality, thin, high resistivity, solar cells can be made using processing compatible with conventional practice. Analysis of I-V and spectral response measurements of these cells confirmed theoretical predictions and thereby pointed to voltages beyond the near 600 mV obtained in this study.

Allison, J. F.↗
NASA NTRS1980

Drag-free estimation feasibility study

A drag compensation system for solar probes and other spacecraft that require a drag-free capability is presented. Estimation techniques, derived from modern control theory, are proposed.

Schaechter, D. B.↗
NASA NTRS1980

Feasibility study consisting of a review of contour generation methods from stereograms

A review of techniques for obtaining contour information from stereo pairs is given. Photogrammetric principles including a description of stereoscopic vision are presented. The use of conventional contour generation methods, such as the photogrammetric plotting technique, electronic correlator, and digital correlator are described. Coherent optical techniques for contour generation are discussed and compared to the electronic correlator. The optical techniques are divided into two categories: (1) image plane operation and (2) frequency plane operation. The description of image plane correlators are further divided into three categories: (1) image to image correlator, (2) interferometric correlator, and (3) positive negative transparencies. The frequency plane correlators are divided into two categories: (1) correlation of Fourier transforms, and (2) filtering techniques.

Kim, C. J.↗
NASA NTRS1980

A feasibility study for advanced technology integration for general aviation

An investigation was conducted to identify candidate technologies and specific developments which offer greatest promise for improving safety, fuel efficiency, performance, and utility of general aviation airplanes. Interviews were conducted with general aviation airframe and systems manufacturers and NASA research centers. The following technologies were evaluated for use in airplane design tradeoff studies conducted during the study: avionics, aerodynamics, configurations, structures, flight controls, and propulsion. Based on industry interviews and design tradeoff studies, several recommendations were made for further high payoff research. The most attractive technologies for use by the general aviation industry appear to be advanced engines, composite materials, natural laminar flow airfoils, and advanced integrated avionics systems. The integration of these technologies in airplane design can yield significant increases in speeds, ranges, and payloads over present aircraft with 40 percent to 50 percent reductions in fuel used.

Kohlman, D. L.↗
NASA NTRS1981

Process feasibility study in support of silicon material task 1

Results for process system properties, chemical engineering and economic analyses of the new technologies and processes being developed for the production of lower cost silicon for solar cells are presented. Analyses of process system properties are important for chemical materials involved in the several processes under consideration for semiconductor and solar cell grade silicon production. Major physical, thermodynamic and transport property data are reported for silicon source and processing chemical materials.

Yaws, C. L.↗
NASA NTRS1981

The radiation-induced rotation of cosmic dust particles: A feasibility study

A crossed beam, horizontal optical trap, used to achieve laser levitation of particles in an effort to determine how solar radiation produces high spin rate in interplanetary dust particles, is described. It is suggested that random variations in albedo and geometry give rise to a nonzero effective torque when the influence of a unidrectional source of radiaton (due to the Sun) over the surface of a interplanetary dust particle is averaged. This resultant nonzero torque is characterized by an asymmetry factor which is the ratio of the effective moment arm to the maximum linear dimension of the body and is estimated to be 5 X 10 to the minus four power. It is hoped that this symmetry factor, which stabilizes the nonstatistical response of the particle, can be measured in a future Spacelab experiment.

Misconi, N. Y.↗
NASA NTRS1981

Automated Plasma Spray (APS) process feasibility study

An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal barrier coatings to aircraft and stationary gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical positioning subsystem incorporating two interlaced six degree of freedom assemblies (one for coating deposition and one for coating thickness monitoring); a noncoherent optical metrology subsystem (for in process gaging of the coating thickness buildup at specified points on the specimen); a microprocessor based adaptive system controller (to achieve the desired overall thickness profile on the specimen); and commerical plasma spray equipment. Over fifty JT9D first stage aircraft turbine blade specimens, ten W501B utility turbine blade specimens and dozens of cylindrical specimens were coated with the APS process in preliminary checkout and evaluation studies. The best of the preliminary turbine blade specimens achieved an overall coating thickness uniformity of 53 micrometers (2.1 mils), much better than is achievable manually. Comparative evaluations of coating thickness uniformity for manually sprayed and APS coated specimens were performed. One of the preliminary turbine blade evaluation specimens was subjected to a torch test and metallographic evaluation. Some cylindrical specimens coated with the APS process survived up to 2000 cycles in subsequent burner rig testing.

Fetheroff, C. W.↗
NASA NTRS1981

Feasibility study of LITVC for shuttle SRB

A liquid injection thrust vector control (LITVC) system for the shuttle solid rocket booster (SRB) was analyzed. The LITVC was compared with the SRB baseline flexible seal. A table of LITVC advantages and disadvantages is presented. It is concluded that the LITVC performs well at low to moderate duty cycles, but not for high duty cycle requirements.

Martin, C. L.↗
NASA NTRS1980

Radiation induced rotation of interplanetary dust particles - A feasibility study for a space experiment

Irregular interplanetary dust particles may acquire a considerable spin rate due to two non-statistical dynamical mechanisms induced by solar radiation. These arise from variations in surface albedo discussed by Radzievskii (1954) and from irregularities in surface geometry discussed by Paddack (1969). An experiment is reported which will lead to an evaluation in space of the effectiveness of these two spin mechanisms. The technique of optical levitation in an argon laser beam provides a stable trap for particles 10-60 microns in diameter. The objective is to design an optical trap for dielectric particles in vacuum to study these rotation mechanisms in the gravity-free environment of a Spacelab experiment.

Ratcliff, K. F.↗
NASA NTRS1981

Feasibility study of a procedure to detect and warn of low level wind shear

A Doppler radar system which provides an aircraft with advanced warning of longitudinal wind shear is described. This system uses a Doppler radar beamed along the glide slope linked with an on line microprocessor containing a two dimensional, three degree of freedom model of the motion of an aircraft including pilot/autopilot control. The Doppler measured longitudinal glide slope winds are entered into the aircraft motion model, and a simulated controlled aircraft trajectory is calculated. Several flight path deterioration parameters are calculated from the computed aircraft trajectory information. The aircraft trajectory program, pilot control models, and the flight path deterioration parameters are discussed. The performance of the computer model and a test pilot in a flight simulator through longitudinal and vertical wind fields characteristic of a thunderstorm wind field are compared.

Turkel, B. S.↗
NASA NTRS1981

Feasibility study of deformation modes of deforming composite materials using visioplasticity method

The impact resistance and the effect of impact on fiber reinforced composite materials was investigated. The visioplastic method for studying deformation modes and transient impact distribution is described and the basic equations used in the visioplastic method are presented. The subroutine for digitizing the input data and a computer program (STRESS) for calculating the strains and stresses of deforming projectiles are presented.

Dwivedi, S. N.↗