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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Cruise performance of an isolated 1.15 pressure ratio turbofan propulsion system simulator at Mach numbers from 0.6 to 0.85

An isolated 1.15 pressure ratio turbofan engine simulator was tested at Mach numbers from 0.6 to 0.85. At Mach 0.75 the net propulsive force of the fan and nacelle (excluding core thrust) was 73 percent of the ideal fan net thrust. Internal losses amounted to 7 percent, and external drag amounted to 20 percent of the ideal fan net thrust. External pressure and friction drag were about equal. The propulsive efficiency with a 90 percent efficient fan would have been 63 percent. For the aerodynamic characteristics of the nacelle that was tested, increasing the fan pressure ratio to approximately 1.35 would have resulted in a maximum propulsive efficiency of 67 percent.

Steffen, F. W.↗
NASA NTRS1974

Relative desirability of leisure activities and work parameters in a simulation of isolated work stations

The kinds of activities that are attractive to man in long duration isolation are delineated considering meaningful work as major activity and a choice of leisure/living provisions. The dependent variables are the relative distribution between various work, leisure, and living activities where external constraints on the subject's freedom of choice are minimized. Results indicate that an average of at least five hours per day of significant meaningful work is required for satisfactory enjoyment of the situation; most other parameters of the situation have less effects on overall performance and satisfaction

Sullins, W. R., Jr.↗
NASA NTRS1973

Electric radiation fields of lightning return strokes in three isolated Florida thunderstorms

Peak value and risetime distributions for the electric radiation fields produced by lightning strokes to ground in three isolated Florida thunderstorms are presented. The storm at 195 km produced about 1000 return strokes having an average peak radiation field (normalized to 100 km) of about 5.5 V/m, the storm at 110 km produced about 700 strokes having 2.0 V/m, and the storm within 10 km produced about 100 strokes having 15.0 V/m. For each storm the average peak radiation field for first strokes was only slightly greater than the average peak field for subsequent strokes. For the sample of three storms the average peak radiation field in a given storm was proportional to the number of subsequent strokes per flash in that storm. The field risetimes for the two distant storms have statistical properties which are essentially identical to those reported for distant storms in Pennsylvania, whereas the close Florida storm exhibited significantly faster risetimes.

Lin, Y. T.↗
NASA NTRS1974

Intensity variation of ELF hiss and chorus during isolated substorms

Electromagnetic ELF emissions (100-1000 Hz) observed on the polar-orbiting OGO-6 satellite within three hours of the dawn-dusk meridian consistently exhibit a predictable response to isolated substorm activity. Near dawn, the emissions intensify during the substorm and then subside following the magnetic activity; the waves are most intense at L greater than 4, exhibit considerable structure and have been primarily identified as chorus. At dusk the response is entirely different; the wave intensity falls to background levels during substorm activity but subsequently intensifies, usually reaching levels well in excess of that before the disturbance. The emissions near dusk extend to low L, are relatively featureless, and have been identified as plasmaspheric hiss. These features are interpreted in terms of changes in the drift orbits of outer-zone electrons which cyclotron resonate with ELF waves.

Thorne, R. M.↗
NASA NTRS1974

Reflection beam isolator for submillimeter wavelengths

Magnetoplasma reflection beam isolators for submillimeter wave use are discussed. The basic configuration used is that of the Kerr transverse magneto-optical effect. Theoretical and experimental data at 337 microns using InSb as a plasma are given.

Kanda, M.↗
NASA NTRS1975

Design and development of a 5 kV isolated solid state switch

A unique microcircuit intended for use as a shorting switch for large extraterrestrial solar cell arrays is described. The packaging design for the 5 kV isolated hybrid switch is different from most hybrid microcircuits in that it utilizes a compartmentalized plastic case (a portion of which is encapsulated), is not hermetic, and is designed for high voltage operation.

Holbrook, R. J.↗
NASA NTRS1974

Arousal and hallucinatory activity under two isolation conditions

Experimental exploration of the hypothesis that soundproof-room and water-immersion isolation environments differ with respect to the variety of physiological responses and reported hallucinations they elicit. The results obtained support the hypothesis in regard to physiological responses only.

Levin, J.↗
NASA NTRS1975

Substorm-associated reconfiguration of the dusk side equatorial magnetosphere - A possible source mechanism for isolated plasma regions

A rapid reconfiguration of the dusk side magnetosphere was observed near the magnetic equator by particle and field experiments aboard Explorer 45 at 1715 UT on June 17, 1972. Following the onset of an 800-gamma negative bay in the auroral zone, Explorer 45, inbound at 1700 MLT and L about 5, observed a sharp dropout of outer zone electrons. Simultaneously, the plasma density dropped from a level typical of the plasmasphere to one typical of the ion trough, and plasma sheet proton fluxes increased, producing a 100-gamma depression in B, in a shift to a taillike configuration. Outer zone electrons with pitch angles near 45 deg returned with delay times consistent with injection near midnight at the time of dropout and eastward drift to the dusk meridian. Approximately 45 min after the reconfiguration, the satellite reentered the plasmasphere, and the electron fluxes returned to previous levels. In the next orbit, approximately 6 hours later, a region of isolated plasma was detected near apogee at 1400 MLT. There is therefore circumstantial evidence that the type of magnetospheric reconfiguration observed here is responsible for the detachment of regions of cold plasma from the plasmasphere.

Barfield, J. N.↗
NASA NTRS1975

Isolated cold plasma regions - Observations and their relation to possible production mechanisms

Regions of enhanced cold plasma, isolated from the main plasmasphere along the Explorer 45 (53-A) orbit in the equatorial plane, have been detected by using the sheath-induced potentials seen by the electric field experiment. The occurrence of these regions has a strong correlation with negative enhancements of Dst, and their locations are primarily in the noon-dusk quadrant. The data support the concept that changes in large-scale convection play a dominant role in the formation of these regions. Plasma tails that are predicted from enhancements of large-scale convection electric fields in general define where these regions may be found. More localized processes are necessary to account for the exact configuration and structure seen in these regions and may eventually result in detachment from the main plasmasphere.

Maynard, N. C.↗
NASA NTRS1975

A millimeter-wave reflection-beam isolator

A new and simple type of millimeter-wave isolator using a solid-state magnetoplasma in a reflection-beam system is described. Some data are presented showing performance at 94 GHz. Practical considerations indicate that performance should be much closer to ideal at higher frequencies.

Kanda, M.↗
NASA NTRS1976

Effect of grazing flow on steady-state resistance of isolated square-edged orifices

Steady state diagnostic testing of an isolated orifice has shown the nature of the interaction between grazing and orifice flow causing the large increase in orifice resistance for both inflow and outflow. A simple inviscid interaction model is developed which uses thin aerofoil theory to account for pressure forces exerted at the interface between the orifice and grazing flow together with a one-dimensional discharge coefficient concept. The effect of grazing flow boundary layer thickness is also included in the model. Resistance measurements for each orifice tested, over a wide range of grazing flow speeds and flow rates, collapse into a single curve when plotted in terms of effective discharge coefficient against orifice to grazing velocity ratio. The correlation curves for inflow and outflow are different. Data for clustered orifices collapse in the same way as those for the single orifice. The effect of boundary layer thickness is compared with model predictions.

Rogers, T.↗
NASA NTRS1976

An experimental and analytical investigation of effect on isolated boattail drag of varying Reynolds numbers up to 130,000,000

An investigation was conducted to determine whether large Reynolds number effects occur on isolated boattails, including an analytical study and tests in a 1/3-meter transonic cryogenic tunnel. This investigation was conducted at an angle of attack of 0 deg at Mach numbers from 0.6 to 0.9 for Reynolds numbers up to 130 million. Results indicate that as the Reynolds number was increased, the static pressure coefficients in the expansion region of the boattail became more negative whereas those in the recompression region became more positive. These two trends were compensating and, as a result, there was only a small effect (if any) of Reynolds numbers on boattail pressure drag.

Reubush, D. E.↗
NASA NTRS1975

Isolation and removal of waste products

Methods of isolation and elimination of waste products in spacecraft cabins are described. The role of waste products in the environment, collection and transport of waste products to storage containers, or to recovery systems, preservation of waste products, and storage and removal of waste products are among the factors discussed. Regeneration of the waste products to recover water and/or oxygen, is briefly considered.

Borshchenko, V. V.↗
NASA NTRS1976

Performance of an isolated two-dimensional wedge nozzle with fixed cowl and variable wedge centerbody at Mach numbers up to 2.01

A wind tunnel investigation has been conducted to determine the aeropropulsion performance (thrust minus drag) of an isolated, two-dimensional wedge nozzle with a simulated variable-wedge mechanism and a fixed cowl. The investigation was conducted statically and at Mach numbers from 0.60 to 1.20 in the Langley 16-foot transonic tunnel and at a Mach number of 2.01 in the Langley 4-foot supersonic pressure tunnel. The ratio of exhaust jet total pressure to free-stream static pressure was varied up to 27 depending on free-stream Mach number. The results indicate that the aeropropulsion performance of the two-dimensional fixed-cowl variable-wedge nozzle is slightly lower (0.7 to 1.4 percent of ideal thrust) than that achieved for a two-dimensional wedge nozzle with a translating shroud, although part of the difference in performance is attributed to internal-performance differences. The effects of cowl boattail angle, internal expansion area ratio, and wedge half-angle on the performance of the two-dimensional wedge nozzle are discussed.

Maiden, D. L.↗
NASA NTRS1976

Rotating stratified flow over finite isolated topography

Inviscid, steady, stratified rotating flow over a finite, isolated topographic feature is critically analyzed. The formulation is based on approximating the horizontal momentum by the geostrophic momentum. A boundary value problem governs the perturbation pressure field. The solution is an anticyclonic, topographically-bound vortex whose characteristics are independent of the upstream velocity but do depend on stratification, rotation, and the nature of the topography. The vortex is baroclinic in the vicinity of the mountain but barotropic in the far field. The velocity field is a combination of the bound vortex and an upstream velocity interacting with the perturbation pressure field. The effects of stratification, upstream velocity and the nature of the topography are investigated, and fluid trajectories are plotted.

Merkine, L.-O.↗
NASA NTRS1977

A shock isolator for diode laser operation on a closed-cycle refrigerator

A device developed to isolate the diode laser from impact shocks delivered during the expansion phase of the Solvay cycle of a helium refrigerator is briefly described. The device uses intermediate cold stations in the stand-off, which permit the stand-off to be short and rigid while minimizing the thermal load at the diode mount.

Jennings, D. F.↗