Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Generators”

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 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

The terminal area automated path generation problem

The automated terminal area path generation problem in the advanced Air Traffic Control System (ATC), has been studied. Definitions, input, output and the interrelationships with other ATC functions have been discussed. Alternatives in modeling the problem have been identified. Problem formulations and solution techniques are presented. In particular, the solution of a minimum effort path stretching problem (path generation on a given schedule) has been carried out using the Newton-Raphson trajectory optimization method. Discussions are presented on the effect of different delivery time, aircraft entry position, initial guess on the boundary conditions, etc. Recommendations are made on real-world implementations.

Hsin, C.-C.↗
NASA NTRS1977

Generator of droplet tracers for holographic flow visualization in water tunnels

Design of a tracer-particle generator for use in holographic flow visualization of complex flow fields is discussed. Desired characteristics of the tracer particles, including a size range of 20 to 200 microns, a spherical shape to facilitate focusing of holograms, and a fluid density near that of ambient particles, are reviewed; a particle injection rate of 100 to 1000 per sec in water tunnels with flow velocities between one and 10 meters per sec is also desirable. The operation of the particle generator, which produces uniform droplets with the specified optical properties, is described.

Charwat, A. F.↗
NASA NTRS1977

Improved scene generator capability

Components of an integrated system having all functions for model preparation and generation, image computation and scene generation, and collision detection and reporting for the visual simulation of space shuttle maneuvers and its interaction with the manipular arm and other objects, as well as during earth landing exercises are described. High surface solution by range priority allows for correct views of dynamically moving objects from any viewpoint. Smooth shading, anti-aliasing and edge smoothing techniques provide a high quality picture. The collision detection system allows for simulation of impenetrable objects and docking maneuvers, and the modeling systems permit production of new data bases for desired simulations.

Source record↗
NASA NTRS1974

Generation of a monodispersed aerosol

The identity and laboratory test methods for the generation of a monodispersed aerosol are reported on, and are subjected to the following constraints and parameters; (1) size distribution; (2) specific gravity; (3) scattering properties; (4) costs; (5) production. The procedure called for the collection of information from the literature, commercial available products, and experts working in the field. The following topics were investigated: (1) aerosols; (2) air pollution -- analysis; (3) atomizers; (4) dispersion; (5) particles -- optics, size analysis; (6) smoke -- generators, density measurements; (7) sprays; (8) wind tunnels -- visualization.

Schenck, H.↗
NASA NTRS1978

On an acoustic field generated by subsonic jet at low Reynolds numbers

An acoustic field generated by subsonic jets at low Reynolds numbers was investigated. This work is motivated by the need to increase the fundamental understanding of the jet noise generation mechanism which is essential to the development of further advanced techniques of noise suppression. The scope of this study consists of two major investigation. One is a study of large scale coherent structure in the jet turbulence, and the other is a study of the Reynolds number dependence of jet noise. With this in mind, extensive flow and acoustic measurements in low Reynolds number turbulent jets (8,930 less than or equal to M less than or equal to 220,000) were undertaken using miniature nozzles of the same configuration but different diameters at various exist Mach numbers (0.2 less than or equal to M less than or equal to 0.9).

Yamamoto, K.↗
NASA NTRS1978

Evaluation of a spacecraft nitrogen generator

A research and development program was successfully completed towards the development of a method of generating nitrogen for cabin leakage makeup aboard space vehicles. The nitrogen generation concept used liquid hydrazine as the stored form of nitrogen. This reduced tankage and expendables weight associated with high pressure gaseous and cryogenic liquid nitrogen storage. The hydrazine was catalytically dissociated to yield a mixture of nitrogen and hydrogen. The latter was separated to provide the makeup nitrogen. The hydrogen will be used in the reduction of metabolic carbon dioxide.

Marshall, R. D.↗
NASA NTRS1978

Transient response to three-phase faults on a wind turbine generator

In order to obtain a measure of its responses to short circuits a large horizontal axis wind turbine generator was modeled and its performance was simulated on a digital computer. Simulation of short circuit faults on the synchronous alternator of a wind turbine generator, without resort to the classical assumptions generally made for that analysis, indicates that maximum clearing times for the system tied to an infinite bus are longer than the typical clearing times for equivalent capacity conventional machines. Also, maximum clearing times are independent of tower shadow and wind shear. Variation of circuit conditions produce the modifications in the transient response predicted by analysis.

Gilbert, L. J.↗
NASA NTRS1978

Procedures for generation and reduction of linear models of a turbofan engine

A real time hybrid simulation of the Pratt & Whitney F100-PW-F100 turbofan engine was used for linear-model generation. The linear models were used to analyze the effect of disturbances about an operating point on the dynamic performance of the engine. A procedure that disturbs, samples, and records the state and control variables was developed. For large systems, such as the F100 engine, the state vector is large and may contain high-frequency information not required for control. This, reducing the full-state to a reduced-order model may be a practicable approach to simplifying the control design. A reduction technique was developed to generate reduced-order models. Selected linear and nonlinear output responses to exhaust-nozzle area and main-burner fuel flow disturbances are presented for comparison.

Seldner, K.↗
NASA NTRS1977

Solar Stirling power generation - Systems analysis and preliminary tests

The feasibility of an electric power generation system utilizing a sun-tracking parabolic concentrator and a Stirling engine/linear alternator is being evaluated. Performance predictions and cost analysis of a proposed large distributed system are discussed. Design details and preliminary test results are presented for a 9.5 ft diameter parabolic dish at the Jet Propulsion Laboratory (Caltech) Table Mountain Test Facility. Low temperature calorimetric measurements were conducted to evaluate the concentrator performance, and a helium flow system is being used to test the solar receiver at anticipated working fluid temperatures (up to 650 or 1200 C) to evaluate the receiver thermal performance. The receiver body is designed to adapt to a free-piston Stirling engine which powers a linear alternator assembly for direct electric power generation. During the next phase of the program, experiments with an engine and receiver integrated into the concentrator assembly are planned.

Selcuk, M. K.↗
NASA NTRS1977

The impact of H2S emissions on future geothermal power generation - The Geysers region, California

The future potential for geothermal power generation in the Geysers region of California is as much as 10 times the current 502 MW(e) capacity. However, environmental factors such as H2S emissions and institutional considerations may play the primary role in determining the rate and ultimate level of development. In this paper a scenario of future geothermal generation capacity and H2S emissions in the Geysers region is presented. Problem areas associated with H2S emissions, H2S abatement processes, plant operations, and government agency resources are described. The impact of H2S emissions on future development and the views of effected organizations are discussed. Potential actions needed to remove these constraints are summarized.

Leibowitz, L. P.↗
NASA NTRS1977

Digital generation of alongwind velocity field

A procedure is described for generating simulation samples of the two-dimensional fluctuating component of the wind velocity acting on the surface of a paraboloidal antenna. A numerical example shows that a simulation sample can be generated rapidly by computer with results that appear reasonable. To complete the performance evaluation of the antenna surface for the random wind velocity, it would be necessary to combine the velocity field with pressure coefficients that can be established for the antenna surface. Loading coefficients could be derived readily from this combination and then standard procedures could be applied for the evaluation of the antenna rms measure of performance in response to the loading.

Shinozuka, M.↗
NASA NTRS1978

Synchronization of wind turbine generators against an infinite bus under gusting wind conditions

Studies of synchronizing a wind turbine generator against an infinite bus are performed on a digital computer. In the digital simulation, wind gusts of different magnitudes and durations are hypothesized. Prior to the synchronization, differences of the frequency and phase position between voltages of the alternator and the bus are also included in the simulation. Solutions for rotor speed, generator power angle, electromagnetic torque, wind turbine torque, wind turbine blade pitch angle, and armature current are simulated and presented graphically. The ERDA-NASA 100-kW wind turbine is used as a case study. The results so obtained will thus have immediate applications.

Hwang, H. H.↗
NASA NTRS1978

Recombination-generation currents in degenerate semiconductors

The classical Shockley-Read-Hall theory of free carrier recombination and generation via traps is extended to degenerate semiconductors. A concise and simple expression is found which avoids completely the concept of a Fermi level, a concept which is alien to nonequilibrium situations. Assumptions made in deriving the recombination generation current are carefully delineated and are found to be basically identical to those made in the original theory applicable to nondegenerate semiconductors.

Von Roos, O.↗
NASA NTRS1978

The generation of gravitational radiation by escaping supernova neutrinos

Formulae for the gravitational radiation due to the anisotropic axisymmetric emission of neutrinos from a small source are derived. We find that a burst of neutrinos released anisotropically from a supernova will generate a burst of gravitational radiation that may be comparable in amplitude and energy to the gravitational radiation generated by the fluid motion in the collapse of the supernova core.

Epstein, R.↗
NASA NTRS1978

Development and evaluation of a hybrid averaged orbit generator

A rapid orbit generator based on a first-order application of the Generalized Method of Averaging has been developed for the Research and Development (R&D) version of the Goddard Trajectory Determination System (GTDS). The evaluation of the averaged equations of motion can use both numerically averaged and recursively evaluated, analytically averaged perturbation models. These equations are numerically integrated to obtain the secular and long-period motion. Factors affecting efficient orbit prediction are discussed and guidelines are presented for treatment of each major perturbation. Guidelines for obtaining initial mean elements compatible with the theory are presented. An overview of the orbit generator is presented and comparisons with high precision methods are given.

Mcclain, W. D.↗
NASA NTRS1979

Arbitrary aircraft-geometry generator

Computer program helps designers to generate detailed configuration geometry with much flexibility in choices of configurations and details of description. Input requirements, program turnaround time, and costs are kept low. It consists of routines that generate fuselage and planar-surface (winglike) geometries and routine that determines true intersection of all components with fuselage.

Edwards, C. L. W.↗
NASA NTRS1979

Analysis of radiation patterns of interaction tones generated by inlet rods in the JT15D engine

Interaction tones were intentionally generated by circumferential arrays of equally spaced rods that protrude radially from the inlet wall near the face of the 28-blade fan. Arrays of 28 and 41 rods, selected to give specific far field radiation properties, were tested. The expected properties were readily apparent in the measured radiation patterns. A more detailed analysis of the test data showed both the precision and limitations of the applied acoustic theory. Rods protruding 23 percent of the radius predominantly generated only lowest radial order modes, as expected. Measured and predicted radiation patterns were generally in good agreement. The agreement, however, depended on a significant degree of implied refraction due to inlet velocity gradients. Refraction, if present, would impact static-flight noise comparisons.

Heidmann, M. F.↗
NASA NTRS1979

A viscous flow analysis for the tip vortex generation process

A three dimensional, forward-marching, viscous flow analysis is applied to the tip vortex generation problem. The equations include a streamwise momentum equation, a streamwise vorticity equation, a continuity equation, and a secondary flow stream function equation. The numerical method used combines a consistently split linearized scheme for parabolic equations with a scalar iterative ADI scheme for elliptic equations. The analysis is used to identify the source of the tip vortex generation process, as well as to obtain detailed flow results for a rectangular planform wing immersed in a high Reynolds number free stream at 6 degree incidence.

Shamroth, S. J.↗