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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 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Nationwide assessment of potential output from wind-powered generators

A method for computing the actual expected power for a wind-powered generator from a given observed speed distribution is described and applied to estimate the potential output for different locations in the continental U.S. A contour map of generator capacity factor values (fraction of the rated output realizable) is obtained for wind-powered generator systems with a cut-in speed of 3.6 m/sec and a rated speed of 8.0 m/sec, and for a unit with hypothetical values for the 1 MW class (cut-in speed, 6.7 m/sec; rated speed, 13.4 m/sec). Results indicate that in the central U.S. and in certain areas of the New England coast at a height of 61 m, over 60% of the rated output power could be obtained on an annual average. In these areas capacity factors of over 20% could be obtained with the 1MW system.

Justus, C. G.↗
NASA NTRS1976

Cost as a technology driver

Cost managment as a guiding factor in optimum development of technology, and proper timing of cost-saving programs in the development of a system or technology with payoffs in development and operational advances are discussed and illustrated. Advances enhancing the performance of hardware or software advances raising productivity or reducing cost, are outlined, with examples drawn from: thermochemical thrust maximization, development of cryogenic storage tanks, improvements in fuel cells for Space Shuttle, design of a spacecraft pyrotechnic initiator, cost cutting by reduction in the number of parts to be joined, and cost cutting by dramatic reductions in circuit component number with small-scale double-diffused integrated circuitry. Program-focused supporting research and technology models are devised to aid judicious timing of cost-conscious research programs.

Fitzgerald, P. E., Jr.↗
NASA NTRS1976

Simulation of flight-type engine fan noise in the NASA-Lewis 9 x 15 anechoic wind tunnel

A major problem in the measurement of aircraft engine fan noise is the difficulty of simulating, in a ground-based facility, the noise that occurs during flight. Flight-type noise as contrasted to the usual ground-static test noise exhibits substantial reductions in both (1) the time unsteadiness of tone noise and (2) the mean level of tones calculated to be nonpropagating or cut-off. A model fan designed with cut-off of the fundamental tone was acoustically tested in the anechoic wind tunnel under both static and tunnel flow conditions. The properties that characterize flight-type noise were progressively simulated with increasing tunnel flow. The distinctly lobed directivity pattern of propagating rotor/stator interaction modes was also observed. The results imply that the excess noise attributed to the ingestion of the flow disturbances that prevail near most static test facilities was substantially reduced with tunnel flow. The anechoic wind tunnel appears to be a useful facility for applied research on aircraft engine fan noise under conditions of simulated flight.

Heidmann, M. F.↗
NASA NTRS1976

A source array for generating higher order acoustic modes in circular ducts

A unique source array has been developed for the generation of both spinning and non-spinning higher order modes in a circular duct. The array consists of two concentric rings of sources. Through individual control of the response of each element, the array provided phase and amplitude control in the radial as well as circumferential directions. Radial modes shapes were measured in a 12-inch diameter anechoically-terminated hollow duct. These modes could be generated at their cut-off frequency and throughout a frequency range extending to the cut-off frequency for the next higher order radial mode. Comparisons are given between theory and experiment for the generation of specific modes. The radial dependence of the measured mode shapes was enhanced considerably by the design of this array. The results indicate a significant improvement over previous mode generation mechanisms. The contamination of the generated mode by additional spurious modes is also considered for variations between individual elements within the source array.

Wyerman, B. R.↗
NASA NTRS1978

"Space slitter" for film or tape

Device cuts film or tape into strips by guiding film in channel under cutting blades. Device is operated by lifting pressure bar to insert blades into film. Film is then pulled through blades. Cutter has potential uses in advertising, commercial art, and publishing fields.

Johnson, W. H.↗
NASA NTRS1979

Precision cleaver for "soft" crystals

"Soft" crystals are cleaved as thin 0.005 inch with special cleaver. Thin slices of soft crystalline materials are used in X-ray spectrometers. Slices are usually cut by hand with wire or blade. Wire tends to scratch surface and to produce slices of nonuniform thickness. Device will rapidly cut soft crystals in smooth, thin, uniform slices.

Benedicto, J. S. J.↗
NASA NTRS1979

Contouring pile-brush seals

Variety of shapes are produced by simple flat machining. Freeze-cut method is cost-efficient by eliminating necessity to cut brushes individually.

Norwood, L. B.↗
NASA NTRS1977

Tissue macerating instrument

A surgical tissue macerating and removal tool is described which has a rotating rod with a cutting member at one end and which disposed in a tube which is then contained in an extension of the tool handle. A frusto-conical member extends into the extension at the cutter member end of the rotating rod with its small end engaging the tube. The portion of the frusto-conical member outside of the extension forms a tissue engaging member and may be cut-off at an angle to the axis of the rod to form a tissue engaging edge. Apertures are provided in the extension adjacent the frusto-concial member so that treatment fluid supplied in the annular space between the tube and the extension may flow to the operative site. An aperture is provided in the frustoconical member between the extension and the tube so that fluid may also flow into the tube where it mixes with macerated tissue being directed through an aperture in the tube to a passageway which may have suction applied to help remove macerated material.

Baehr, E. F.↗
NASA NTRS1978

Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

Fabrication of a prototype large capacity multiple blade slurry saw is considered. Design of the bladehead which will tension up to 1000 blades, and cut a 45 cm long silicon ingot as large as 12 cm in diameter is given. The large blade tensioning force of 270,000 kg is applied through two bolts acting on a pair of scissor toggles, significantly reducing operator set-up time. Tests with an upside-down cutting technique resulted in 100% wafering yields and the highest wafer accuracy yet experienced with MS slicing. Variations in oil and abrasives resulted only in degraded slicing results. A technique of continuous abrasive slurry separation to remove silicon debris is described.

Holden, S. C.↗
NASA NTRS1978

Surface acoustic wave stabilized oscillators: Additional aging results

Updated aging data for SAW oscillators with aluminum transducers on ST-cut quartz, for gold transducers on ST-cut quartz, and for aluminum transducers on SiO2/LiTaO3. Devices with gold transducers age differently (both and shape of curve) from those having a aluminum transducers indicating the transducer metallization can represent an important aging mechanism.

Source record↗
NASA NTRS1978

Travelling neutral disturbances and minor constituent particle mass

The mass cut-offs for critical or resonant coupling of minor species acoustic waves (so-called travelling neutral disturbances) and acoustic-gravity waves in the main atmosphere are shown and explained. The effects of vertical temperature gradients and the diffusion of the minor species on the mass cut-offs are also demonstrated. The wave characteristics of these minor species waves are examined. The wave number surface is shown to be such that energy and group velocity directions are more nearly vertical than those of gravity waves for the same phase velocity direction. It is expected that these coupled waves, when properly excited, will act to damp gravity waves and redistribute energy vertically. Implications for the thermosphere and mesosphere are discussed. Under ordinary conditions such resonant coupling is judged more likely for lighter mass species, such as helium and hydrogen.

Gross, S. H.↗
NASA NTRS1980

Improved table-saw guard

Guard makes lighter contact on materials being sawed. Cuts are better controlled, and damages to fragile foam-type materials are reduced. Overhead support makes it possible to perform slot and step cuts, and thick materials are pushed under guard with less force. Guard is transparent plastic enclosure held by side-attached overhead support arm.

Dunn, B. R.↗
NASA NTRS1980

Structurally-continuous composite corners

Flat composite materials are cut at certain angles to form boxes with corners as thick as walls. Patterns produce uniform corners, and cuts are structured so that shear loads are transferred from ply to ply instead of across one surface.

Jackson, A. C.↗
NASA NTRS1979

Coal-shale interface detection

A penetrometer for coal-shale interface detection is presented. It is used with coal cutting equipment consisting of a reciprocating hammer, having an accelerometer mounted thereon to measure the impact of the hammer as it penetrates the ceiling or floor surface of a mine. Additionally, a pair of reflectometers simultaneously view the same surface, and the outputs from the accelerometer and reflectometers are detected and jointly registered to determine when an interface between coal and shale is being cut through.

Broussard, P. H.↗
NASA NTRS1979

Fabrication and testing of composite ring specimens

The tooling and techniques used in the fabrication of composite laminate tubes of any desired ply orientation and stacking sequence are described along with techniques for cutting ring specimens under internal pressure. The method consists of laying up the tube on a central circular mandrel, and by means of internal pressure, expanding the prepreg tube against the cavity wall of an external mold tool, which forms the geometric curing envelope for the tube. Tube quality is assessed by laminate wall thickness measurement, by hoop strength measurement on rings cut from the ends of the tube, and by ultrasonic inspection.

Liber, T.↗
NASA NTRS1979

Isis 1 observations at the source of auroral kilometric radiation

Observations of auroral kilometric radiation (AKR) were made by Isis 1 in the source region. The radiation is found to be generated in the extraordinary mode just above the local cut-off frequency and to emanate nearly perpendicular to the magnetic field. It occurs within local depletions of electron density, where the ratio of plasma frequency to cyclotron frequency is less than 0.2. The density depletion is restricted to altitudes above about 2000 km, and the upper AKR frequency limit corresponds to the extraordinary cut-off frequency at this altitude. AKR is observed from Isis 1 above the nighttime auroral zone over a wider extent in longitude than in latitude with an intense source region observed most often near 2200 LMT and 70 deg invariant latitude. It is directly related to inverted V electron precipitation events with an electron-to-wave energy conversion efficiency of the order of 0.1 to 1%.

Benson, R. F.↗
NASA NTRS1980

Precision filament cutter

Automated cutter precisely chops filaments of glass, graphite, plastic, and other materials into fibers for use in composites and other applications. Cutter uses movable blade that is pushed and pulled across fixed blade. Because mass of movable blade is small and stroke is short, operation is fast, and wear and energy consumption are low. Blade cuts on both forward and return movements. Operator selects fiber length and chopping rate. After each cut, blast of air blows filament away so it can be collected.

Mchatton, A. D.↗