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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 1,801 records · Page 100
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Mean elements of GEOS-1 and GEOS-2

A combined analytical-numerical procedure for determining precise mean orbital elements is presented and applied to the orbits of GEOS-1 and GEOS-2. The precision of the mean semi-major axes of these orbits is a few tens of centimeters when optical flash data is used to determine two-day orbital arcs. Four-day Minitrack orbits give mean semi-major axes of a few meters precision. The mean orientation parameters are obtained to a precision of about 0.1 sec (about 3m) or better from the optical orbits. This precision is adequate for determinations of tidal parameters, particularly in the case of GEOS-2, where the tidal perturbation of the inclination is 10 sec.

Douglas, B. C.↗
NASA NTRS1972

Visual phenomena induced by cosmic rays and accelerated particles

Experiments, conducted at cyclotrons together with observations by Apollo astronauts, suggest with little doubt that cosmic nuclei interacting with the visual apparatus cause the phenomenon of light flashes seen on translunar and transearth coast over the past four Apollo missions. Other experiments with high and low energy neutrons and a helium ion beam suggest that slow protons and helium ions with a stopping power greater than 10 to the 8th power eV/gram sq cm can cause the phenomenon in the dark adapted eye. It was demonstrated that charged particles induced by neutrons and helium ions can stimulate the visual apparatus. Some approaches to understanding the long term mission effects of galactic cosmic nuclei interacting with man and his nervous system are outlined.

Tobias, C. A.↗
NASA NTRS1972

Atomization, drop size, and penetration for cross-stream water injection at high-altitude reentry conditions with application to the RAM C-1 and C-3 flights

Atomization, drop size, and penetration data are presented for cross stream water injection at conditions simulating high altitude reentry (low Weber number, high static temperature, high Knudsen number, and low static pressure). These results are applied to the RAM C-1 and C-3 flights. Two primary breakup modes are considered, vapor pressure or flashing and aerodynamic atomization. Results are given for breakup boundaries and mean drop size for each of these atomization mechanisms. Both standard and flight orifice geometries are investigated. The data were obtained in both a static environment and in conventional aerodynamic facilities at Mach numbers of 4.5 and 8. The high temperature aspects of reentry were simulated in a Mach 5.5 cyanogen-oxygen tunnel with total temperature of 4500 K.

Gooderum, P. B.↗
NASA NTRS1972

Study of sulfospinels

Several new compounds with the formula AB2S4 were synthesized. Pressure-induced polymorphism of the sulfospinels was investigated. Sulfospinels which produced new high-pressure phases were NiRh2S4, FeYb2S4, In2S3, CrIn2S4, NiIn2S4, CoIn2S4 and MnIn2S4. The only sulfospinels which transformed to the NiAs derivatives were those in which A and B atoms had unfilled d-orbitals. P-T phase relations were investigated for a series of sulfochromites. Thin films of several ACr2S4 sulfospinels were prepared by a flash evaporization technique on the (111) and (100) planes of NaCl and on the (100) plane of Mgo.

Tressler, R. E.↗
NASA NTRS1971

Characterization of hot hydrogen-atom reactions by kinetic spectrography.

The flash photolysis of hydrogen iodide in the presence of nitrous oxide, carbon dioxide, and water has been investigated by kinetic spectroscopy. Although the fraction of hydrogen iodide dissociated was very large, the only observable intermediate was imidogen. It was demonstrated that the rapid removal of imidogen and the apparent absence of hydroxyl radicals in each case is a result of the following two reactions, respectively: (1) NH + HI yields NH2 + I; and (2) OH + HI yields H2O + I.

Tomalesky, R. E.↗
NASA NTRS1971

Analysis of pilot warning indicator performance in terminal area traffic.

Three pilot warning indicator concepts for collision hazard avoidance are analyzed using computer fast-time simulation. A hazard measure is defined based on a 1/2-g maximum horizontal acceleration, a maximum climb or dive angle of 10 deg for each aircraft, and a 20-sec warning time, through escape completion. The traffic model is based on flight tracks recorded in the Atlanta terminal area over an 11 hr period during August 1967. The basic PWI concept studied alarms on range to flashing beacons mounted on intruder aircraft as a function of relative azimuth and elevation. The alarm-hazard epoch ratio is about 17/1 to maintain the missed-alarm rate below 10%. Beacon vignetting or range-rate discrimination are shown to reduce the false-alarm rate by about 75%.

Ruetenik, J. R.↗
NASA NTRS1972

Field emission energy distributions of hydrogen and deuterium on the /100/ and /110/ planes of tungsten.

Total energy distributions of field emitted electrons from the tungsten (110) and (100) planes as a function of coverage by hydrogen and deuterium have been recorded utilizing a spherical deflection energy analyzer. The elastic tunneling resonance spectrum gives a plot of the 'local density of states' in the adsorbate. The inelastic tunneling spectrum reveals those discrete excitation energies available in the adsorbate-substrate complex. These spectroscopic data have been used to infer the chemical nature of the binding states which have been observed in the flash desorption spectrum of hydrogen from tungsten.

Plummer, E. W.↗
NASA NTRS1972

Relativistic electrons in space.

This paper reviews the current state of knowledge concerning relativistic electrons, above 0.3 MeV, in interplanetary space, as measured by detectors on board satellites operating beyond the influence of the magnetosphere. The electrons have a galactic component, which at the lower energies is subject both to solar modulation and to spasmodic 'quiet time' increases and a direct solar component correlated with flare activity. The recent measurements have established the form of the differential energy spectrum of solar flare electrons. Electrons have been detected from flares behind the visible solar disk. Relativistic electrons do not appear to leave the sun at the time of the flash phase of the flare, although there are several signatures of electron acceleration at this time. The delay is interpreted as taking place during the transport of the electrons through the lower corona.

Simnett, G. M.↗
NASA NTRS1972

Location of the electron acceleration region in solar flares.

Observations of impulsive solar flare X rays (energy greater than 10 keV) by the OGO-5 satellite and the measurements of energetic solar electrons made with the Explorer-35 and Explorer-41 (IMP-5) satellites during the period March 1968-September 1969 have been analyzed in order to determine the ion density in the X-ray source region as well as the location of the electron acceleration region in the solar atmosphere. The ion density in the X-ray source region varies from event to event and lies between 1 and 100 billion ions per cu cm for those events in which the impulsive X-ray emission could be detected; for those events in which no impulsive emission was detected above threshold, the ion density in the X-ray source was less than one billion ions per cu cm. At least in some small solar flares, the region where the electrons are accelerated during the flash phase is located in the lower corona.

Kane, S. R.↗
NASA NTRS1972

Popping phenomena with the hydrazine nitrogen-tetroxide propellant system.

The propellant spray resulting from the impingement of liquid jets of hydrazine and nitrogen tetroxide has been studied at atmospheric pressure by means of streak photography. The streak photographs show periodic small explosions that originate near the impingement point and propagate through the propellant spray at velocities of 3000 to 5000 fps, consuming all propellant droplets over a distance of up to 6 in. Typical streak photographs are presented. The frequency of the explosions or pops ranged up to several hundred cps, and could be controlled by varying the contact time in the liquid phase. Below a minimum threshold contact time, popping did not take place. At high values of contact time, the popping rate was controlled by the transit time of the free jet before impingement. Flashing of the oxidizer prior to impingement prevented popping under certain conditions. It is postulated that popping is initiated by liquid phase reactions. A mechanism for the occurrence of popping and its relation to reactive stream separation is suggested.

Houseman, J.↗
NASA NTRS1972

Lightning criteria relative to space shuttles: Currents and electric field intensity in Florida lightning

The measured electric field intensities of 161 lightning strokes in 39 flashes which occurred between 1 and 35 km from an observation point at Kennedy Space Center, Florida during June and July of 1971 have been analyzed to determine the lightning channel currents which produced the fields. In addition, typical channel currents are derived and from these typical electric fields at distances between 0.5 and 100 km are computed and presented. On the basis of the results recommendations are made for changes in the specification of lightning properties relative to space vehicle design as given in NASA TMX-64589 (Daniels, 1971). The small sample of lightning analyzed yielded several peak currents in the 100 kA range. Several current rise-times from zero to peak of 0.5 microsec or faster were found; and the fastest observed current rate-of-rise was near 200 kA/microsec. The various sources of error are discussed.

Uman, M. A.↗
NASA NTRS1972

Studies of oscillatory combustion and fuel vaporization

Research projects involving oscillatory combustion and fuel vaporization are reported. Comparisons of experimental and theoretical droplet vaporization histories under ambient conditions such that the droplet may approach its thermodynamic critical point are presented. Experimental data on instantaneous heat transfer from a gas to a solid surface under conditions of oscillatory pressure with comparisons to an unsteady one-dimensional model are analyzed. Droplet size and velocity distribution in a spray as obtained by use of a double flash fluorescent method were investigated.

Borman, G. L.↗
NASA NTRS1973

System for indicating direction of intruder aircraft

A pilot warning indicator system consisting of a flashing beacon, a detector, and an indicating panel is described. The detector responds to radiant energy from another aircraft's beacon by energizing particular signal lamps positioned in the periphery of the pilot's normal field of view. Since the positions of the energized lamps are related to the direction from which radiant energy is received by the detector, the pilot is apprised of the relative position of an intruder aircraft without any shift in visual fixation.

Story, A. W.↗
NASA NTRS1972

EC/LSS thermal control system study for the space shuttle

The results of a parametric weight analysis of heat rejection systems for the space shuttle orbiter are presented. Integrating the suborbital heat rejection system with the overall heat rejection system design and the possible use of a common system for both on-orbit and suborbital operations require an overall system and parametric analyses applicable to all mission phases. The concept of equivalent weights, with weight penalties assigned for power, induced aircraft drag and radiator area is used to determine weight estimates for the following candidate systems: vapor cycle refrigeration, gas cycle refrigeration, radiators (space and atmospheric convectors), expendable heat sinks, and ram air. The orbiter power penalty, ram air penalty, and radiator weight penalty are analyzed. The vapor compression system and an expendable fluid system utilizing a multifluid spraying flash evaporator are selected as the two most promising systems. These are used for maximum on-orbit heat rejection in combination with or as a supplement to a space radiator.

Howell, H. R.↗
NASA NTRS1973

A high-speed photographic system for flow visualization in a steam turbine

A photographic system was designed to visualize the moisture flow in a steam turbine. Good performance of the system was verified using dry turbine mockups in which an aerosol spray simulated, in a rough way, the moisture flow in the turbine. Borescopes and fiber-optic light tubes were selected as the general instrumentation approach. High speed motion-picture photographs of the liquid flow over the stator blade surfaces were taken using stroboscopic lighting. Good visualization of the liquid flow was obtained. Still photographs of drops in flight were made using short duration flash sources. Drops with diameters as small as 30 micrometers (0.0012 in.) could be resolved. In addition, motion pictures of a spray of water simulating the spray off the rotor blades and shrouds were taken at normal framing rates. Specially constructed light tubes containing small tungsten-halogen lamps were used. Sixteen millimeter photography was used in all cases. Two potential problems resulting from the two-phase turbine flow (attenuation and scattering of light by the fog present and liquid accumulation on the borescope mirrors) were taken into account in the photographic system design but not evaluated experimentally.

Barna, G. J.↗
NASA NTRS1973

Noncontacting devices to indicate deflection and vibration of turbopump internal rotating parts

The research is reported which was conducted to develop devices for measuring vibrations and deflections of parts, such as impellers, shafts, turbine wheels, and inducers in operating turbopumps. Three devices were developed to the breadboard stage: ultrasonic Doppler transducer, flash X-rays, and light-pipe reflectance. It was found that the X-ray technique is applicable to the shaft assembly and the turbine seal of the J-2 pump, and the light-pipe-reflectance device appears to be ideal for cryogenic pump sections.

Hamilton, D. B.↗
NASA NTRS1973

Simultaneous observation solutions for NASA-MOTS and SPEOPT station positions on the North American datum

Simultaneous observations of the GEOS-I and II flashing lamps by the NASA MOTS and SPEOPT cameras on the North American Datum (NAD) were analyzed using geometrical techniques to provide an adjustment of the station coordinates. Two separate adjustments were obtained. An optical data only solution was computed in which the solution scale was provided by the Rosman-Mojave distance obtained from a dynamic station solution. In a second adjustment, scaling was provided by processing simultaneous laser ranging data from Greenbelt and Wallops Island in a combined optical-laser solution. Comparisons of these results with previous GSFC dynamical solutions indicate an rms agreement on the order of 4 meters or better in each coordinate. Comparison with a detailed gravimetric geoid of North America yields agreement of 3 meters or better for mainland U.S. stations and 7 and 3 meters, respectively, for Bermuda and Puerto Rico.

Reece, J. S.↗
NASA NTRS1973

Thermophysical properties of plasma sprayed coatings

Thermophysical properties of plasma sprayed materials were determined for the following plasma sprayed materials: CaO - stabilized ZrO2, Y2O3 - stabilized ZerO2, Al2O3, HfO2 Mo, nichrome, NiAl, Mo-ZrO2, and MoAl2O3 mixtures. In all cases the thermal conductivity of the as-sprayed materials was found to be considerably lower than that of the bulk material. The flash-laser thermal diffusivity technique was used both for diffusivity determination of single-layer materials and to determine the thermal contact resistance at the interface of two-layer specimens.

Wilkes, K. E.↗

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