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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 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Jet noise from coaxial nozzles over a wide range of geometric and flow parameters

Free field pure jet noise data were taken for a large range of coaxial nozzle configurations. The core nozzles were circular (1 to 4 in. diam.) and plug types. The fan to core area ratio varied from 0.7 to 43.5, while the velocity ratio typically varied from 0 to 1. For most cases the two nozzles were coplanar but large axial extensions of either nozzle were also tested. Correlation of the data resulted in a simple procedure for estimating ambient temperature subsonic coaxial jet noise spectra over a wide range of geometric and flow parameters.

Olsen, W.↗
NASA NTRS1974

Computation of steady nozzle flow by a time-dependent method

The equations of motion governing steady, inviscid flow are of a mixed type, that is, hyperbolic in the supersonic region and elliptic in the subsonic region. These mathematical difficulties may be removed by using the so-called time-dependent method, where the governing equations become hyperbolic everywhere. The steady-state solution may be obtained as the asymptotic solution for large time. The object of this research was to develop a production type computer program capable of solving converging, converging-diverging, and plug two-dimensional nozzle flows in computational times of 1 min or less on a CDC 6600 computer.

Cline, M. C.↗
NASA NTRS1974

A technique for generating shear waves in cylindrical shells under radial impact

Experimental techniques are developed to study and measure the shear-wave velocity in an aluminum cylindrical shell subjected to a radial impact. The radial impact is obtained by exploding an electrical detonator inserted in plastic plugs mounted on the end of the shell. Strain gages, mounted on the outside surface of the shell at various axial locations, are used to obtain oscilloscope traces from which the shear-wave velocity can be calculated.

Blum, A.↗
NASA NTRS1972

Intermediate term frequency measurements with the HP computing counter in the USNO clock time system

High precision frequency measurements with various integration times can be made with conventional counters by using variable gate times. The Hewlett-Packard (HP) computing counter allows such measurements over a wide range of frequencies and measurement times. This instrument can also convert period measurements into frequency by means of its arithmetic capabilities: The program library contains programs to facilitate frequency stability measurements in the most direct and convenient way. This method was used as the basis for all time scale computations, until requirements for highest resolution justified the development of an automatic data acquisition system. The phase measurements are now being made with the HP computing counter (with time interval plug-in unit) under program control from the HP System Programmer.

Winkler, G. M. R.↗
NASA NTRS1974

Signal conditioner test set

A system was developed for testing components contained in a signal conditioning module with a transistor and capacitor included in a circuit. The system includes a housing with a socket into which the module to be tested is plugged. A test switch is provided for selectively connecting a variable load to either a transistor or capacitor in the circuit for testing the operation. A signal generating circuit is provided for generating signals for use in testing the components of the module.

Houck, W. H.↗
NASA NTRS1975

A three-electrode streamer chamber

A three electrode streamer chamber has been designed with basic components consisting of two glass boxes with overall dimensions 1.00 x 500 x 200 cu m filled with neon at 1 atm. Serving as a high voltage pulse source is a nanosecond voltage pulse generator with cutoff discharges at 16 atm nitrogen pressure. The discharges are designed for obtaining an adjustable pulse with an amplitude of 600 kV and a nanosecond pump. To match the chamber electrodes with the oscillator, the electrodes are manufactured in the shape of a three-wire strip line. The cutoff discharger plug-in and the operating instructions are also described here.

Nurgozhin, N. N.↗
NASA NTRS1975

A Thruster Sub-System Module (TSSM) for solar electric propulsion

Solar Electric Propulsion (SEP) is currently being studied for possible use in a number of near-earth and planetary missions. Thruster systems for these missions could be integrated directly into a spacecraft or modularized into a Thruster Sub-System Module (TSSM). A TSSM for electric propulsion missions would consist of a 30-cm ion thruster, thruster gimbal system, propellant storage and feed system, associated Power Processing Unit (PPU), thermal control system and complete supporting structure. The TSSM would be wholly self-contained and be essentially a plug-in or strap-on electric stage with simple mechanical, thermal, electrical and propellant interfaces. The TSSM described in this report is designed for a broad range of missions requiring from two to ten TSSM's mounted in a 2 by x configuration. The thermal control system is designed to accommodate waste heat from the power processor based on realistic efficiencies when the TSSM is operating from 0.7 to 3.5 AU's. The modules are 0.61 M (2 ft) wide by 2.29 M (7.5 ft) long and have a dry weight including propellant tank of 54.4 kg (120 lb). The propellant tank will hold 145.1 kg (320 lb) of mercury.

Sharp, G. R.↗
NASA NTRS1975

Radiation of cylindrical duct acoustic modes with flow mismatch

Calculations for the radiation of spinning acoustic modes, with or without a centerbody, and with or without flow temperature and velocity discontinuity, are presented. Solutions to the appropriate convected wave equations devised around Fourier transforms and Wiener-Hopf technique are presented. The decomposition of the asymmetric kernel, resulting from a flow and temperature mismatch, is carried out in part exactly and partially using the so-called Carrier-Koiter approximation procedure. The resulting solutions offer a good approximation to the radiation of both symmetric and asymmetric modes through a flow discontinuity represented as a plug flow jet issuing from a cylindrical duct. Besides the Koiter approximation, the major limitation on the calculation program is the difficulty of calculating the high order Bessel functions with sufficient accuracy.

Savkar, S. D.↗
NASA NTRS1975

Effect of inlet ingestion of a wing tip vortex on compressor face flow and turbojet stall margin

A two-dimensional inlet was alternately mated to a coldpipe plug assembly and a J85-GE-13 turbojet engine, and placed in a Mach 0.4 stream so as to ingest the tip vortex of a forward mounted wing. Vortex properties were measured just forward of the inlet and at the compressor face. Results show that ingestion of a wing tip vortex by a turbojet engine can cause a large reduction in engine stall margin. The loss in stall compressor pressure ratio was primarily dependent on vortex location and rotational direction and not on total-pressure distortion.

Mitchell, G. A.↗
NASA NTRS1975

The generation of gravitational waves. I - Weak-field sources

This paper derives and summarizes a 'plug-in-and-grind' formalism for calculating the gravitational waves emitted by any system with weak internal gravitational fields. If the internal fields have negligible influence on the system's motions, the formalism reduces to standard 'linearized theory'. Independent of the effects of gravity on the motions, the formalism reduces to the standard 'quadrupole-moment formalism' if the motions are slow and internal stresses are weak. In the general case, the formalism expresses the radiation in terms of a retarded Green's function for slightly curved spacetime and breaks the Green's function integral into five easily understood pieces: direct radiation, produced directly by the motions of the source; whump radiation, produced by the 'gravitational stresses' of the source; transition radiation, produced by a time-changing time delay ('Shapiro effect') in the propagation of the nonradiative 1/r field of the source; focusing radiation, produced when one portion of the source focuses, in a time-dependent way, the nonradiative field of another portion of the source; and tail radiation, produced by 'back-scatter' of the nonradiative field in regions of focusing.

Thorne, K. S.↗
NASA NTRS1976

Full-coverage film cooling heat transfer study: Summary of data for normal-hole injection and 30 deg slant-hole injection

Heat transfer to a full coverage film cooled turbulent boundary layer over a flat surface was studied. The surface consisted of a discrete hole test section containing 11 rows of holes spaced 5 diameters apart in a staggered array and an instrumented recovery region. Ten diameter spacing was also studied by plugging appropriate holes. Two test sections were used, one having holes normal to the surface and the other having holes angled 30 deg to the surface in the downstream direction. Stanton number data were obtained both in the full coverage region and in the downstream recovery region for a range of blowing ratios, or mass flux ratios, from 0 to 1.3. Initial conditions at the upstream edge of the blowing region were varied from 500 to 5000 for momentum thickness Reynolds number and from 100 to 1800 for enthalpy thickness Reynolds number. The range of Reynolds numbers based on hole diameter and mainstream velocity was 6000 to 22000. Initial boundary layer thicknesses range from 0.5 to 2.0 hole diameters. Air was used as the working fluid. The data were taken for the secondary injection temperature equal to the wall temperature and also equal to the mainstream temperature. Superposition was then used to obtain Stanton number as a continuous function of the injectant temperature. The heat transfer coefficient was defined on the basis of a mainstream-to-wall temperature difference. This definition permits direct comparison of performance between film cooling and transpiration cooling.

Crawford, M. E.↗
NASA NTRS1976

Three dimensional thrust chamber life prediction

A study was performed to analytically determine the cyclic thermomechanical behavior and fatigue life of three configurations of a Plug Nozzle Thrust Chamber. This thrust chamber is a test model which represents the current trend in nozzle design calling for high performance coupled with weight and volume limitations as well as extended life for reusability. The study involved the use of different materials and material combinations to evaluate their application to the problem of low-cycle fatigue in the thrust chamber. The thermal and structural analyses were carried out on a three-dimensional basis. Results are presented which show plots of continuous temperature histories and temperature distributions at selected times during the operating cycle of the thrust chamber. Computed structural data show critical regions for low-cycle fatigue and the histories of strain within the regions for each operation cycle.

Armstrong, W. H.↗
NASA NTRS1975

Dewar technology study

The development of a Dewar system for handling liquid helium under weightless conditions is described. Porous plug designs for the prevention of superfluid creep out of the dewar through the vent line were evaluated. For the purpose of designing a neck to provide a transition from the cold cavity to the outside, the loads carried by the neck and equipment supports were studied. Temperature, pressure, and mass flow instrumentation for monitoring Dewar performance were also evaluated. In addition, multilayer blankets consisting of aluminized Mylar separated by Dacron net sheets were designed to insulate the pressure vessel. The dewar system is suggested for use with the star tracking telescope aboard the relativity satellite.

Davis, W.↗
NASA NTRS1976

Mariner Jupiter/Saturn LCSSE thruster/valve assembly and injection propulsion unit rocket engine assemblies: 0.2-lbf T/VA development and margin limit test report, addendum

Capillary tube plugging phenomena on the 0.2-lbf thruster/valve assembly was examined. Vibration tests were conducted in the nozzle up attitude. Failure to fire caused by blockage of the capillary tube by catalyst fines was observed after vibration. Water flushing and previbration hot firing were used to remove the fines.

Wilson, W. W.↗
NASA NTRS1975

Radiation of cylindrical duct acoustic modes with flow mismatch

Motivated by the problem of Mach number and temperature discontinuity mismatch between the tailpipe and the surrounding medium, and the effect of this flow mismatch on aircraft engine noise, the radiation of spinning turbo-acoustic modes from a round duct is investigated. The model, based on a plug flow exhaust jet, solves the convected wave equations using Fourier transforms, inversion being accomplished via a coupled Wiener-Hopf and Carrier-Koiter technique. It is concluded that the Mach number discontinuity results in a conflict between convection and refraction effects, while the temperature mismatch results in a sharp beaming of sound off to the side.

Savkar, S. D.↗
NASA NTRS1975

Fiber optic multiplexed optical transmission systems for space vehicle launch facilities

Low loss Fiber Optic Cable is being evaluated as a potential future replacement for Kennedy Space Center's 13,000 mile Wideband cable system. In order to make economical use of the wide bandwidth characteristic of glass fibers, a Frequency Division Multiplexing (FDM) scheme has been devised to stack many analog and digital data channels on a single fiber. The Multiplexed Optical Transmission System (MOTS) will offer a unique flexibility of plug-in modularity to meet changing data and bandwidth requirements in addition to the standard 'goodies' of immunity to lightning and other EMI, RFI type interferences, and of smaller size and lighter weight.

Bell, C. H.↗
NASA NTRS1977

Multiplexed fiber-optic transmission system

Digital, audio, and video data channels spanning 100 megahertz bandwidth are transmitted via single fiber-optical link. System is flexible by virtue of its plug-in modularity and optical patchboard that allows it to adjust to data and bandwidth changes.

Bell, C. H.↗