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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

What determines the location of satellites and planets?

The discrete structural pattern in the distribution of the satellites and planets around their primaries has since its discovery been thought to hold the key to the origin and evolution of the solar system. Different attempts to rationalize this distribution are reviewed with emphasis on theories with foundation in verifiable physical processes. Foremost among these is the band structure theory, which relates the emplacement of interstellar dust and gas source material around the magnetized primarily to the critical velocity for ionization of the four major interstellar gas components. The uncertainties, that are inevitable in all reconstructions, are in this theory compensated by the support from precise manifestations of the 2/3 effect in the Saturnian ring system and in the asteroid belt, and by the reproduction of related phenomena in laboratory and space experiments.

Arrhenius, G.↗
NASA NTRS1984

Methane concentrations and source strengths in urban locations

The results of a six year measurement of trace gases in 18 different urban and remote areas throughout the Northern and Southern Hemispheres are reported. It is found that the measurements are consistent with a yearly atmospheric release of 30 to 60 megatons of CH4 in urban environments. Concentrations of CCl3F, CCl2F2, and CH3CCl3 were also found to be higher in the same urban samples than in corresponding samples from remote areas. The 'urban excess' (urban concentration minus remote concentration) was generally 1000 to 2000 times larger on a molar basis for CH4 than for CCl3F. The fraction of world-wide methane release occurring in the urban environment is estimated from the concentration ratios for CH4 vs CCl3F. It is shown that about 8 to 15 percent of atmospheric methane release occurs in urban areas.

Blake, D. R.↗
NASA NTRS1985

Experimental study of forward-located jet-interaction nozzles

The effects of forward-mounted sonic jet-interaction nozzles with one, three equal, or one large and two small orifices on the transitional or turbulent boundary-layer flow over a biconic (9-deg-25-arcmin/6-deg) model at angle of attack -10 to the 15 deg and Reynolds number 8.10 x 10 to the 6th/ft are investigated experimentally using pressure taps, force measurements, oil-flow visualization, and schlieren photography in the 20-in. Mach-6 wind tunel at NASA Langley. The injection flow rates are 0.055 and 0.026 lbm/s, with stagnation pressure 500 psia, stagnation temperature 1000 R, and dynamic pressure 8.7 psia. The results are presented in diagrams, graphs, and photographs and characterized. Moment amplification factors of 1.0 or better (maximum 1.8 at angle of attack 15 deg and flow rate 0.055 lbm/s) are observed for all nozzle types, but the configuration with three unequal orifices is found to give improvements of 10 percent over the single-orifice nozzle at a given flow rate.

Cavalleri, R. J.↗
NASA NTRS1985

Solar cycle dependence of the location of the Venus bow shock

Initial measurements of the Venus bow shock obtained by Pioneer Venus in 1979 near solar maximum indicated that the bow shock was on average 2.44 RV from the center of the planet in the terminator plane. This is 0.35 RV further from Venus than observed by Venera 9/10 in 1976. In the past this discrepancy has been attributed to some effect of the solar cycle. Recent measurements by Pioneer Venus support this interpretation. In 1980 the distance to the bow shock reached a maximum of 2.45 RV and since then has been almost steadily declining toward the distance measured by Venera near solar minimum. The variation in bow shock position is well correlated with the sunspot number and the F 10.7 cm flux over this period. This behavior is attributed to the variation in the neutral atmosphere of Venus with the solar cycle and its subsequent effect on the mass-loading of the solar wind.

Alexander, C. J.↗
NASA NTRS1986

Convective heat transfer from circular cylinders located within perforated cylindrical shrouds

The influence of perforated cylindrical shrouds on the convective heat transfer to circular cylinders in transverse flow has been studied experimentally. Geometries studied were similar to those used in industrial platinum resistance thermometers. The influence of Reynolds number, ventilation factor (ratio of the open area to the total surface area of shroud), radius ratio (ratio of shroud's inside radius to bare cylinder's radius), and shroud orientation with respect to flow were studied. The experiments showed that perforated shrouds with ventilation factors in the range 0.1 to 0.4 and radius ratios in the range 1.1 to 2.1 could enhance the convective heat transfer to bare cylinders up to 50%. The maximum enhancement occurred for a radius ratio of 1.4 and ventilation factors between 0.2 and 0.3. It was found that shroud orientation influenced the heat transfer, with maximum heat transfer generally occurring when the shroud's holes were centered on either side of the stagnation line. However, the hole orientation effect is of second order compared to the influence of ventilation factor and radius ratio.

Daryabeigi, K.↗
NASA NTRS1986

Vertical drop test of a transport fuselage section located aft of the wing

A 12-foot long Boeing 707 aft fuselage section with a tapering cross section was drop tested at the NASA Langley Research Center to measure structural, seat, and occupant response to vertical crash laods and to provide data for nonlinear finite element modeling. This was the final test in a series of three different transport fuselage sections tested under identical conditions. The test parameters at impact were: 20 ft/s velocity, and zero pitch, roll, and yaw. In addition, the test was an operational shock test of the data acquisition system used for the Controlled Impact Demonstration (CID) of a remotely piloted Boeing 720 that was crash tested at NASA Ames Dryden Flight Research Facility on December 1, 1984. Post-test measurements of the crush showed that the front of the section (with larger diameter) crushed vertically approximately 14 inches while the rear crushed 18 inches. Analysis of the data traces indicate the maximum peak normal (vertical) accelerations at the bottom of the frames were approximately 109 G at body station 1040 and 64 G at body station 1120. The peak floor acceleration varied from 14 G near the wall to 25 G near the center where high frequency oscillations of the floor were evident. The peak anthropomorphic dummy pelvis normal (vertical) acceleration was 19 G's.

Fasanella, E. L.↗
NASA NTRS1985

Shuttle near-field environmental impacts - Conclusions and observations for launching at other locations

Near field and far field environmental monitoring activities extending from the first launch of the Space Shuttle at the Kennedy Space Center have provided a database from which conclusions can now be drawn for short term, acute effects of launch and, to a lesser degree, long term cumulative effects on the natural environment. Data for the first 15 launches of the Space Shuttle from Kennedy Space Center Pad 39A are analyzed for statistical significance and reduced to graphical presentations of individual and collective disposition isopleths, summarization of observed environmental impacts (e.g., vegetation damage, fish kills), and supporting data from specialized experiments and laboratory analyses. Conclusions are drawn with regard to the near field environment at Pad A, the effects on the lagoonal complex, and the relationships of these data and conclusions to upcoming operations at Complex 39 Pad B where the environment is significantly different. The paper concludes with a subjective evaluation of the likely impacts at Vandenberg Space Launch Complex 6 for the first Shuttle launch next year.

Koller, A. M., Jr.↗
NASA NTRS1987

Locating Sonic Lines in Transonic Nozzles

New set of formulas for positions of sonic lines enables more accurate determination of pressures, heat transfers, and flow-discharge coefficients in advanced convergent/divergent nozzles. Older, closedform approximate solutions of Sauer type used to determine best position. In advanced nozzles with shorter transonic fields, such approximations no longer adequate.

Wagner, W. R.↗
NASA NTRS1986

Radiometric responsivity determination for Feature Identification and Location Experiment (FILE) flown on space shuttle mission

A procedure was developed to obtain the radiometric (radiance) responsivity of the Feature Identification and Local Experiment (FILE) instrument in preparation for its flight on Space Shuttle Mission 41-G (November 1984). This instrument was designed to obtain Earth feature radiance data in spectral bands centered at 0.65 and 0.85 microns, along with corroborative color and color-infrared photographs, and to collect data to evaluate a technique for in-orbit autonomous classification of the Earth's primary features. The calibration process incorporated both solar radiance measurements and radiative transfer model predictions in estimating expected radiance inputs to the FILE on the Shuttle. The measured data are compared with the model predictions, and the differences observed are discussed. Application of the calibration procedure to the FILE over an 18-month period indicated a constant responsivity characteristic. This report documents the calibration procedure and the associated radiometric measurements and predictions that were part of the instrument preparation for flight.

Wilson, R. G.↗
NASA NTRS1986

Magnetic location of C IV events in the quiet network

Ultraviolet Spectrograph and Polarimeter (UVSP) observations of C IV intensity in the quiet sun were examined and compared to magnetograms and He I 10830 A spectroheliograms from Kitt Peak National Laboratory. The observations were made between 3 and 9 April, 1985. Spatially rastered UVSP intensity measurements were obtained at 11 wavelength positions in the 1548 A line of C IV. It was concluded that the stochastic process whereby convective shuffling of loop footprints leads to many topically dissipative events in active regions and the larger bipoles treated here continues to operate in regions of fewer, weaker flux loops, but the resulting events above threshold are less frequent.

Porter, Jason G.↗
NASA NTRS1987

Application of the complex cepstrum to the location of acoustic sources near reflective surfaces

The complex cepstrum is used to correct bearing estimations of acoustic sources in the presence of a reflective surface. An automated liftering procedure is used which zeros out a block portion of the cepstrum including the echo information. The problem of the resulting distortion is alleviated by applying a coherence criterion to the recovered direct signals at each microphone. Thus to a large degree the interactive nature of cepstral processing is overcome for this application. For the test signals and geometries considered the cepstrum is shown to accurately correct for bearing errors in acoustic signals contaminated with reflections from nearby surfaces.

Fuller, C. R.↗
NASA NTRS1986

Interplanetary magnetic field control of the Venus magnetosheath field and bow shock location

Six Venus years of Pioneer Venus Orbiter (PVO) data are analyzed in a coordinate system which isolates magnetic effects. The field draping pattern features two lobes easily identifiable even in the near planet region. The magnetosheath magnetic magnitude has a hemispherical asymmetry controlled by the IMF orientation in a manner suggesting preferrential ion pickup in one hemisphere. This result complements recent findings that the bow shock position is responsive to IMF direction. Examination of the ionopause position to evaluate ionospheric effects on the overall asymmetry of thfe Venus-solar wind interaction produces negative but not conclusive results.

Phillips, J. L.↗
NASA NTRS1987

Constraints on the mass-radius relation for the neutron star in the X-ray burst source 4U/MXB 1820-30 located in the globular cluster NGC 6624

From the spectral evolution of seven X-ray bursts observed from 4U/MXB 1820-30 (Haberl et al., 1986) during the phases of photospheric expansion and cooling, constraints are derived on the mass-radius relation of the neutron star in this system. Taking into account the uncertainty in the source distance and the possible anisotropy of the burst emission. If during bursts with radius expansion the outer layers of the neutron star are of a hydrogen-poor composition, none of the current equations of state of high-density matter is excluded. For a hydrogen-rich composition, only very soft equations of state are allowed.

Van Paradijs, J.↗
NASA NTRS1987

Highly ionized interstellar gas located in the Galactic disk and halo

High-resolution IUE absorption line spectra have been obtained for 40 distant stars in order to study the distribution of interstellar H I, Si IV, C IV, and N V in the Galactic disk and lower halo. Respective midplane densities of 2 x 10 to the -9th, 7 x 10 to the -9th, and 3 x 10 to the -9th are found for Si IV, C IV, and Ni V. Both column density and velocity data indicate that the highly ionized gas (HIG) is considerably more extended in directions away from the Galactic plane than is H I or Si II. The absorption-line velocities for the halo HIG are consistent with the notion that halo gas in the inner Galaxy rotates more slowly than gas in the underlying disk. The derived column densities suggest an exponential scale height for the HIG of about 3 kpc; however, a simple exponential distribution is a poor representation of the distribution of the gas. It is concluded that a full explanation of the origin of the halo HIG will probably require a blending of ideas from the Galactic fountain and the photoionized halo models.

Savage, Blair D.↗