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Jones, E.

Publications and source records attributed to Jones, E..

18 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

High temperature superconducting infrared imaging satellite

A low earth orbiting platform for an infrared (IR) sensor payload is examined based on the requirements of a Naval Research Laboratory statement of work. The experiment payload is a 1.5-meter square by 0.5-meter high cubic structure equipped with the imaging system, radiators, and spacecraft mounting interface. The orbit is circular at 509 km (275 nmi) altitude and 70 deg. inclination. The spacecraft is three-axis stabilized with pointing accuracy of plus or minus 0.5 deg. in each axis. The experiment payload requires two 15-minute sensing periods over two contiguous orbit periods for 30 minutes of sensing time per day. The spacecraft design is presented for launch via a Delta 2 rocket. Subsystem designs include attitude control, propulsion, electric power, telemetry, tracking and command, thermal design, structure, and cost analysis.

Angus, B.↗
NASA NTRS1989

Space station automation of common module power management and distribution

The purpose is to automate a breadboard level Power Management and Distribution (PMAD) system which possesses many functional characteristics of a specified Space Station power system. The automation system was built upon 20 kHz ac source with redundancy of the power buses. There are two power distribution control units which furnish power to six load centers which in turn enable load circuits based upon a system generated schedule. The progress in building this specified autonomous system is described. Automation of Space Station Module PMAD was accomplished by segmenting the complete task in the following four independent tasks: (1) develop a detailed approach for PMAD automation; (2) define the software and hardware elements of automation; (3) develop the automation system for the PMAD breadboard; and (4) select an appropriate host processing environment.

Miller, W.↗
NASA NTRS1988

VLBI tracking of the TDRS

The use of radio interferometry is being investigated by NASA/Goddard Space Flight Center as a means to track the TDRS geostationary satellites. This technique offers the advantages of very high accuracy using a ground network confined to the continental U.S. and minimal (or no) impact on spacecraft systems as the downlink transmissions can be used passively. A demonstration experiment was performed using very long baseline interferometry (VLBI). The TDRS-E was observed at S-band over a 28-hour definitive period together with dual X/S-band calibration observations of quasars. An orbit was determined for TDRS-E which agrees within estimated error bars with the orbit solution from NASA's operational tracking system but with about half the uncertainty. It was found that, for S-band tracking, the ionosphere is the largest source of orbit error. Use of Ku-band tracking instead would permit geostationary orbits accurate at the 10-m level.

Ray, J.↗
NASA NTRS1980

The effects of leading edge modifications on the post-stall characteristics of wings

An investigation of the effects of leading edge modifications on the post-stall characteristics of two rectangular planform wings in a series of low speed wind tunnel tests is presented. Abrupt discontinuities in the leading edge shape of the wings were produced by placing a nose glove over a portion of the span or by deflecting sections of a segmented leading edge flap. Six component balance data, oil flow visualization photographs, and pressure distribution measurements were obtained, and tests made to study the development of flow separation at stall on small scale planform wing models. Results of oil flow visualization tests at and beyond stall showed the formation of counter-rotating swirl patterns on the upper surface of the '2-D' and '3-D' wings, and results of a numerical lifting line technique applied to wings with leading edge modifications are included.

Winkelmann, A. E.↗
NASA NTRS1979

A computational fluid dynamic technique valid at the centerline for non-axisymmetric problems in cylindrical coordinates

A technique is described for the numerical solution of non-axisymmetric flow problems posed in cylindrical coordinates when the z-axis is included in the flowfield. The highlight of the technique is the manner in which the singularities at the centerline are handled. Specifically, the governing flowfield equations at r = 0 are put in a special form by applying L'Hospital's Rule. The required radial derivatives are evaluated using a one-sided, second-order accurate, first-difference. This leads to a smooth, convergent calculation of the flowfield at the centerline. This appears to be the first generally applicable numerical method for avoiding coordinate system singularities in the context of a finite-difference scheme, and could have application to many nonaxisymmetric flows. The technique is illustrated by specific results for the time-dependent flowfield inside an internal combustion engine.

Griffin, M. D.↗
NASA NTRS1978

Computational fluid dynamics applied to flows in an internal combustion engine

The reported investigation is a continuation of studies conducted by Diwakar et al. (1976) and Griffin et al. (1976), who reported the first computational fluid dynamic results for the two-dimensional flowfield for all four strokes of a reciprocating internal combustion (IC) engine cycle. An analysis of rectangular and cylindrical three-dimensional engine models is performed. The working fluid is assumed to be inviscid air of constant specific heats. Calculations are carried out of a four-stroke IC engine flowfield wherein detailed finite-rate chemical combustion of a gasoline-air mixture is included. The calculations remain basically inviscid, except that in some instances thermal conduction is included to allow a more realistic model of the localized sparking of the mixture. All the results of the investigation are obtained by means of an explicity time-dependent finite-difference technique, using a high-speed digital computer.

Griffin, M. D.↗
NASA NTRS1971

Effects of viscosity and constraints on the dispersion and dissipation of waves in large blood vessels. I.

Investigation of the effects of blood viscosity on dissipation as well as dispersion of small waves in arteries and veins by means of a parametric study. A linearized analysis of axisymmetric waves in a cylindrical membrane that contains a viscous fluid indicates that there are two families of waves: a family of slow waves and one of fast waves. The faster waves are shown to be more sensitive to variations in the elastic properties of the medium surrounding the blood vessels and at high values of the frequency parameter alpha. At low values of alpha the effects of viscosity on attenuation are reversed.

Jones, E.↗
NASA NTRS1971

Effects of viscosity and constraints on the dispersion and dissipation of waves in large blood vessels. II.

Comparison of previously described theoretical predictions with in vivo data from anesthetized dogs. It is shown that the observed attenuation of the pressure and axial waves cannot be accounted for by fluid viscosity alone. For large values of the frequency parameter alpha, the previous analysis is extended to include the effects of viscoelasticity of the vessel wall. The results indicate that the speeds of both types of waves are essentially unaffected by a realistic viscoelasticity model while the attenuation per wavelength is significantly increased and becomes frequency independent. There is fair agreement between theory and experiment.

Jones, E.↗