Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “RADIAL DISTRIBUTION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Some initial ISEE-1 results on the ring current composition and dynamics during the magnetics storm of December 11, 1977

On December 11, 1977 the ISEE-1 spacecraft traversed the equatorial magnetosphere in the prenoon and dawn sectors during the early recovery phase of a magnetic storm with peak DST of -125 gamma. Along the dayside leg O(+) was comparable to or exceeded H(+) in number density in the energy range 0.1-17 keV. The velocity distribution of O(+) showed a characteristic dispersion, consistent with the ions being transported to the dayside from the dusk to midnight sector. The high-energy slope of the H(+) and O(+) distribution functions showed different radial dependence, with the slope of H(+) being consistent with a harder component carrying most of the energy density.

Lennartsson, W.↗
NASA NTRS1978

Investigation of impingement region and wall jets formed by the interaction of high aspect ratio lift jets and a ground plane

Flow characteristics of impinging jets emanating from rectangular exit area converging nozzles of exit area aspect ratio four, six, and eight were investigated. Azimuthal distributions of wall jet radial momentum flux in the ground plane were strongly directional and sensitive to rectangular nozzle exit area aspect ratio, jet impingement angle, and height above ground, H/D. Effects of jet exit velocity profile nonuniformities were also investigated. Data from the single nozzle rectangular jet impringement investigations were incorporated into an existing VTOL aircraft ground flow field computer program. It is suggested that this program together with the Douglas Neumann program modified for V/STOL applications may be used for the analysis and prediction of flow fields and resulting forces and moments on multijet V/STOL aircraft hovering in ground effect.

Kotansky, D. R.↗
NASA NTRS1983

Spectrophotometric studies of the Io Torus

A toroidal volume near Io's orbit is made luminous by multiple optical and ultraviolet line emissions excited by resonant scattering of sunlight and by electron collisions. These emitting atoms and ions have been lost from Io. The spectrophotometric measurements of these emissions and their physical interpretation are considered. It is now known that the flow of material from Io dominates the particle and energy budgets of the Jovian magnetosphere. The observed emitting species in the Io torus are examined, and the atomic clouds are discussed, taking into account morphology and kinematics, atomic cloud supply rates, ion-atom collisions, and charge-exchange collisions. Observations and studies concerning the plasma torus are reported, giving attention to the forbidden lines, the extreme ultraviolet lines, and aspects of ion temperature and spatial distribution. Two types of radial transport in the Io torus include the ballistic motion of neutrals escaping from Io and the cross-L transport of ions.

Brown, R. A.↗
NASA NTRS1984

Kinematics of Saturn's spokes

Voyager 2 images of Saturn's rings have been analyzed for spoke activity. More than 80 and 40 different spokes have been measured at the morning and at the evening ansa, respectively. Higher rate of spoke formation has been found at 145 + or 15 deg SLS and at 305 + or - 15 deg SLS which persisted for at least 3 Saturn revolutions. Higher spoke activity (formation and growth in width) by more than a factor 3 has been observed over the nightside hemisphere of Saturn than over the dayside hemisphere. The age distribution (i.e., time from radial formation until observation, assuming Keplerian shear) of the leading (old) edges of spokes has its maximum at approximately 9,000 s and 6,000 s for spokes observed at the morning ansa and at the evening ansa, respectively. The highest spoke age observed is approximately 20,000 s.

Gruen, E.↗
NASA NTRS1988

Acoustically excited heated jets. 3: Mean flow data

This is Part 3 of a report on the excitability of heated jets under the influence of acoustic excitation. The effects of upstream internal acoustic excitation on jet mixing were described in Part 1. Part 2 described the effects of external excitation on flow mixing. Part 3 contains quantitative results from the measurements of mean Mach number and temperature and consists of radial profiles and centerline distributions measured at selected jet operating conditions for internally excited and unexcited jets. The mean flow data are presented in both graphical and tabulated forms. For the sake of completeness, this part contains temperature probe calibration curves also.

Lepicovsky, J.↗
NASA NTRS1987

Tomographical transformation of Malvern spray measurements

A new method is described which directly transforms Malvern line-integral data into point measurements of the radial drop mean size distribution and liquid volume concentration distribution. The transformed results have been compared with experimental point measurements by photography and the phase/Doppler spray analyzer. The comparison reveals the relation between point measurements and line-of-sight measurements. Three kinds of nozzles were investigated. After tomographical transformation of the Malvern results the different structures of the spray are revealed. A newly derived formula simplifies the transformation procedure. This method provides a direct means to extend the applicability of the Malvern particle sizer and has the potential to be developed for use in unsymmetric sprays.

Zhu, H. M.↗
NASA NTRS1990

The energetic ion substorm injection boundary

In this paper, 167 dispersionless energetic ion injections which were observed by AMPTE CCE are identified. The radial and local time distribution of the events as a function of kp is qualitatively similar to that envisioned in the injection boundary model of Mauk and McIlwain (1974). It is argued that particles observed during dispersionless injections are locally energized during the disruption of the cross-tail current sheet. Therefore, the injection boundary is identified as derived from the spatial distribution of dispersionless injections, with the earthward edge of the region of the magnetotail which undergoes current sheet disruption during the substorm expansion phase. It is shown that this qualitative model for the generation of the injection boundary can provide an explanation for the dispersionless nature, the double spiral shape, and the Kp dependence of the boundary.

Lopez, R. E.↗
NASA NTRS1990

The spiral-compact galaxy pair AM 2208-251: Computer simulations versus observations

The system AM2208-251 is a roughly edge-on spiral extending east-west with a smaller round compact E system about 60 arcsec east of the spiral nucleus along the major axis of the spiral. Bertola, Huchtmeier, and Zeilinger (1990) have presented optical spectroscopic as well as single dish 21 cm observations of this system. Their spectroscopic data show, via emission lines lambda lambda 3727-29A, a rising rotation curve near the nucleus. These spectroscopic observations may indicate a tidal interaction in the system. In order to learn more about such pairs, the authors simulated the interaction using the computer model developed by Miller (1976 a,b, 1978) and modified by the authors (Byrd 1986, 1987, 1988). To do the simulation they need an idea of the mutual orbits of the two galaxies. Their computer model is a two-dimensional polar N-body program. It consists of a self-gravitating disk of particles, within an inert axially symmetric stabilizing halo potential. The particles are distributed in a 24(radial) by 36(azimuthal) polar grid. Self consistent calculations can be done only within the grid area. The disk is modeled with a finite Mestel disk, where all the particles initially move in circular orbits with constant tangential velocities (Mestel 1963), resulting in a flat rotation curve. The gas particles in the spiral's disk, which make up 30 percent of its mass, collide in the following manner. The number of particles in each bin of the polar grid is counted every time step. If it is greater than a given critical density, all the particles in the bin collide, obtaining in the result the same velocities, equal to the average for the bin. This process produces clumps of gas particles-the star formation sites. The authors suppress the collision in the inner part of the disk (within the circle r = 6) to represent the hole seen in the gas in the nuclear bulge of spirals. They thus avoid spurious effects due to collisions in that region. They also varied the size of the collisional bins, which did not affect their conclusions.

Klaric, Mario↗
NASA NTRS1991

The formation of molecules in protostellar winds

The production and destruction processes for molecules in very fast protostellar winds are analyzed and modeled with a one-dimensional chemical kinetics code. Radial density and temperature distributions suggested by protostellar theory are explored as are a range of mass-loss rates. The efficiency of in situ formation of heavy molecules is found to be high if the wind temperature falls sufficiently rapidly, as indicated by theory. The degree of molecular conversion is a strong function of the mass-loss rate and of density gradients associated with the acceleration and collimation of the wind. Even in cases where essentially all of the heavy atoms are processed into molecules, a significant fraction of atomic hydrogen remains so that hghly molecular, protostellar winds are able to emit the 21-cm line. Although CO has a substantial abundance in most models relevant to very young protostars, high abundances of other molecules such as SiO and H2O signify more complete association characteristic of winds containing regions of very high density. Although the models apply only to regions close to the protostar, they are in qualitative accord with recent observations at much larger distances of both atomic and molecular emission from extremely high-velocity flow.

Glassgold, A. E.↗
NASA NTRS1992

Phase space densities in the Uranian plasma sheet

Based on its ionic composition, the magnetosphere of Uranus appears to contain little plasma of solar wind origin. If the plasma source is the atmosphere of the planet, both adiabatic convection with uniform losses and radial diffusion would imply negative radial gradients of the distribution function at fixed first and second adiabatic invariants. The analysis of LECP data in the outer magnetosphere reveals different gradients. Evidence is presented that ions may have been non-adiabaticaly heated during the fourth plasma sheet immersion although this is not unambiguously distinguishable from a source at large down tail distance.

Hammond, C. M.↗
NASA NTRS1993

The backscattered Lyman-alpha glow emission as a signature of the termination shock

The location of the termination shock is a problem of great interest in astrophysics and the current availability of deep space probes with UV detectors has made it possible in principle to remotely sense the termination shock. The method depends upon a measurement of the neutral hydrogen distribution which results from the presence of the heliospheric plasma structure. The charge exchange interaction between the inflowing neutral hydrogen and the plasma structure leads to an observable modification of the inflowing hydrogen distribution. Hence, both the radial dependence of the backscattered Lyman-alpha glow and the absolute difference in the upstream and downstream glow brightness are modified. Recent Voyager 1 and 2 and Pioneer 10 spacecraft data are consistent with the presence of a termination shock. The observational evidence and theoretical models from which a termination shock is inferred will be presented.

Gangopadhyay, P.↗
NASA NTRS1992

Behavior of streamwise rib vortices in a three-dimensional mixing layer

The structure and behavior of a streamwise rib vortex in a direct numerical simulation of a time-developing three-dimensional incompressible plane mixing layer is examined. Where the rib vortex is being stretched, the vorticity vector is primarily directed in the vortex axial direction and the radial and azimuthal velocity distribution is similar to that of a Burger's vortex. In the region where the vortex stretching is negative, there is a change in the local topology of the vortex. The axial flow is decelerated and a negative azimuthal component of vorticity is induced. These features are characteristic of vortex breakdown. The temporal evolution of the rib vortex is similar to the evolution of an axisymmetric vortex in the early stages of vortex breakdown. The effect of vortex breakdown on other parts of the flow is, however, not as significant as the interaction between the rib vortex and other vortices.

Lopez, J. M.↗
NASA NTRS1988

Measurement of the steady surface pressure distribution on a single rotation large scale advanced prop-fan blade at Mach numbers from 0.03 to 0.78

The aerodynamic pressure distribution was determined on a rotating Prop-Fan blade at the S1-MA wind tunnel facility operated by the Office National D'Etudes et de Recherches Aerospatiale (ONERA) in Modane, France. The pressure distributions were measured at thirteen radial stations on a single rotation Large Scale Advanced Prop-Fan (LAP/SR7) blade, for a sequence of operating conditions including inflow Mach numbers ranging from 0.03 to 0.78. Pressure distributions for more than one power coefficient and/or advanced ratio setting were measured for most of the inflow Mach numbers investigated. Due to facility power limitations the Prop-Fan test installation was a two bladed version of the eight design configuration. The power coefficient range investigated was therefore selected to cover typical power loading per blade conditions which occur within the Prop-Fan operating envelope. The experimental results provide an extensive source of information on the aerodynamic behavior of the swept Prop-Fan blade, including details which were elusive to current computational models and do not appear in the two-dimensional airfoil data.

Bushnell, Peter↗
NASA NTRS2002

Companions to isolated elliptical galaxies: revisiting the Bothun-Sullivan (1977) sample using the NASA/IPAC extragalactic database

We investigate the number of physical companion galaxies for a sample of relatively isolated elliptical galaxies. The NASA/IPAC Extragalactic Database (NED) has been usedto reinvestigate the incidence of satellite galaxies for a sample of 34 elliptical galaxies, firstinvestigated by Bothun & Sullivan (1977) using a visual inspection of Palomar Sky Survey prints out to a projected search radius of 75 kpc. We have repeated their original investigation usingdata cataloged data in NED. Nine of these ellipticals appear to be members of galaxy clusters:the remaining sample of 25 galaxies reveals an average of +1.0 f 0.5 apparent companions per galaxy within a projected search radius of 75 kpc, in excess of two equal-area comparisonregions displaced by 150-300 kpc. This is nearly an order of magnitude larger than the +0.12+/- 0.42 companions/galaxy found by Bothun & Sullivan for the identical sample. Making use of published radial velocities, mostly available since the completion of the Bothun-Sullivan study,identifies the physical companions and gives a somewhat lower estimate of +0.4 companions per elliptical. This is still a factor of 3x larger than the original statistical study, but giventhe incomplete and heterogeneous nature of the survey redshifts in NED, it still yields a firmlower limit on the number (and identity) of physical companions. An expansion of the searchradius out to 300 kpc, again restricted to sampling only those objects with known redshifts in NED, gives another lower limit of 4.3 physical companions per galaxy. (Excluding fiveelliptical galaxies in the Fornax cluster this average drops to 3.5 companions per elliptical.)These physical companions are individually identified and listed, and the ensemble-averagedradial density distribution of these associated galaxies is presented. For the ensemble, the radial density distribution is found to have a fall-off consistent with p c( R^-0.5 out to approximately150 kpc. For non-Fornax cluster companions the fall-off continues out to the 300-kpc limit of thesurvey. The velocity dispersion of these companions is found to be constant with projected radial distance from the central elliptical, holding at a value of approximately +/- 300-350 km/sec overall.

NED NASA/IPAC Extragalactic Database↗
NASA NTRS1994

Supersymmetry and radial squeezed states for Rydberg wave packets

Atomic supersymmetry provides an analytical effective-potential model useful for describing certain aspects of Rydberg atoms. Experiments have recently demonstrated the existence of Rydberg wave packets localized in the radial coordinated with p-state angular distribution. This paper shows how atomic supersymmetry can be used to treat radial Rydberg wave packets via a particular analytical type of squeezed state, called a radial squeezed state.

Bluhm, Robert↗