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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Slip casting and extruding shapes of rhenium with metal oxide additives. 1: Feasibility demonstration

The feasibility of fabricating small rhenium parts with metal oxide additives by means of slip casting and extrusion techniques is described. The metal oxides, ZrO2 and HfO2 were stabilized into the cubic phase with Y2O3. Additions of metal oxide to the rhenium of up to 15 weight percent were used. Tubes of 17 mm diameter with 0.5 mm walls were slip cast by adapting current ceramic oxide techniques. A complete cast double conical nozzle demonstrated the ability to meet shapes and tolerances. Extrusion of meter long tubing lengths of 3.9 mm o.d. x 2.3 mm i.d. final dimension is documented. Sintering schedules are presented to produce better than 95% of theoretical density parts. Finished machining was found possible were requried by electric discharge machining and diamond grinding.

Barr, F. A.↗
NASA NTRS1985

Feasibility of steady-state, multi-megawatt MPD thrusters

The feasibility of operating the MPD thruster at sustained, multi-megawatt power levels for application to nuclear powered earth orbital maneuvering and outer planet orbiters is addressed by examining cathode erosion processes. The cathode is studied first since it operates in the most severe environment. Due to current, power, and geometrical constraints imposed by the need for high thruster efficiency the cathode must provide 200-400 A/sq cm at incandescent temperatures. This level must be sustained for hundreds of hours to propel a 13,000 kg payload, 5 MW vehicle from low earth orbit to say geosynchronous orbit in 7 days. The physics of thermionic emission are shown by experiment and theory to dominate the thermal balance and cathode sheath such that electron cooling keeps the cathode cool enough to avoid rapid evaporation. Experiments using a subscale MPD test device operating at continuous power levels of 10-30 kW show that cathode temperature can be kept to 2100-2200 K at the high current densities required for a full-sized, multi-megawatt thruster.

King, D. Q.↗
NASA NTRS1986

A feasibility study on the numerical modeling of interior noise fields

New developments in electronics and computer control have made active methods of noise suppression feasible. To date, however, active methods of noise control have been applied principally in geometrically uniform spaces with localized sound sources. The purpose of this paper is to demonstrate how finite element techniques may be used to model sound fields and active control inside geometrically complex spaces with non-uniform acoustic boundaries and multiple spatially separated sources. A closed-form solution is derived for the case of a one-dimensional tube with a vibrating piston at each end. Results are compared with finite element solutions and the problem is then generalized to two-dimensions with non-uniform geometry and non-uniform acoustic boundaries.

Abrahamson, A. L.↗
NASA NTRS1986

Space-based laser-driven MHD generator: Feasibility study

The feasibility of a laser-driven MHD generator, as a candidate receiver for a space-based laser power transmission system, was investigated. On the basis of reasonable parameters obtained in the literature, a model of the laser-driven MHD generator was developed with the assumptions of a steady, turbulent, two-dimensional flow. These assumptions were based on the continuous and steady generation of plasmas by the exposure of the continuous wave laser beam thus inducing a steady back pressure that enables the medium to flow steadily. The model considered here took the turbulent nature of plasmas into account in the two-dimensional geometry of the generator. For these conditions with the plasma parameters defining the thermal conductivity, viscosity, electrical conductivity for the plasma flow, a generator efficiency of 53.3% was calculated. If turbulent effects and nonequilibrium ionization are taken into account, the efficiency is 43.2%. The study shows that the laser-driven MHD system has potential as a laser power receiver for space applications because of its high energy conversion efficiency, high energy density and relatively simple mechanism as compared to other energy conversion cycles.

Choi, S. H.↗
NASA NTRS1987

The feasibility and design of optical sensors for modal control

The feasibility of optical type sensors for control of flexible bodies was examined. The accuracies of such systems were determined via simulation and the sources of potential errors were designated. An initial laboratory design was effected and preliminary results obtained. These results are discussed critically with applications to future studies and system designs.

Lundquist, Charles A.↗
NASA NTRS1985

Feasibility of expert systems to enhance Space Station subsystem controllers

Results are described from a project to build a prototype expert system for automated fault isolation and correction of a regenerative CO2 removal device that is typical of functions of the air revitalization group in the Space Station environmental control and life support system (ECLSS). The software was developed using one of the powerful commercial knowledge engineering environments. The goal of the project was to evaluate the feasibility of using a software development environment to rapidly design, construct, test, and change expert system software. The use of expert systems to enhance automatic controllers and the use of information on device design and on device troubleshooting and repair procedures in developing expert systems are discussed.

Malin, J. T.↗
NASA NTRS1987

The feasibility of periodicity searches in gamma-ray astronomy

It is presently noted that, in some cases, the usually infeasible conduct of searches in gamma-ray astronomy can be rendered feasible by means of a time-smoothing technique that yields only a moderate sensitivity loss. The total observing time is subdivided into a convenient number m of subintervals, and summing the values of H of each of the subintervals. This will reduce the number of independent frequency values by a factor m due to the shorter observing time.

Buccheri, R.↗
NASA NTRS1987

Feasibility of mapping velocity flowfields in an SSME powerhead using laser anemometry techniques

Nonintrusive anemometry measurement techniques are investigated for a NASA study of steady and unsteady aerothermal flow phenomena present in three engine component flow environments in the Space Shuttle Main Engine powerhead, the: (1) high-pressure fuel turbopump preburner; (2) turbine; and (3) turnaround duct. Issues considered include identification of feasible means of optical access to the high-pressure high-temperature measurement flow regions, and measurement system compatibility with the test environment. Descriptions of the two-component LDV and Laser Two Focus measurement systems are given whose capabilities include measurements of the time-averaged values of velocity magnitude and flow direction, turbulence intensity, and velocity component correlations.

Pelaccio, D. G.↗
NASA NTRS1986

Feasibility study on 8PSK, QPSK, TFM, by using CLASS for Space Station/TDRSS real measured channel

The feasibility of transmitting 500 Mbps data rate through the TDRSS real channel (about 2.5 bits/sec/Hz) for the Space Station application is studied in this paper. The modulation schemes examined are octal phase shift keying, quarternary phase shift keying, and tamed frequency modulation scheme. The software tool used is the Communication Link Analysis and Simulation System. A channel equalizer is shown to be required for such application. Sensitivity results, eye diagrams, and phase trajectory diagrams are presented for discussions.

An, Song H.↗
NASA NTRS1987

Carbon Dioxide Observational Platform System (CO-OPS), feasibility study

The Carbon Dioxide Observational Platform System (CO-OPS) is a near-space, geostationary, multi-user, unmanned microwave powered monitoring platform system. This systems engineering feasibility study addressed identified existing requirements such as: carbon dioxide observational data requirements, communications requirements, and eye-in-the-sky requirements of other groups like the Defense Department, the Forestry Service, and the Coast Guard. In addition, potential applications in: earth system science, space system sciences, and test and verification (satellite sensors and data management techniques) were considered. The eleven month effort is summarized. Past work and methods of gathering the required observational data were assessed and rough-order-of magnitude cost estimates have shown the CO-OPS system to be most cost effective (less than $30 million within a 10 year lifetime). It was also concluded that there are no technical, schedule, or obstacles that would prevent achieving the objectives of the total 5-year CO-OPS program.

Bouquet, D. L.↗
NASA NTRS1987

The feasibility of using TAE as the UIL for the space station and for other internal NASA tasks and projects

This description of the Transportable Applications Executive (TAE) is intended to serve to test the feasibility of its use as the Space Station User Interface Language (SSUIL). TAE was developed by the Space Data and Computing Division, Space and Earth Sciences Directorate of NASA/GSFC, and by Century Computing, Inc. in 1980. TAE is an executive program which ties a system of application programs into a single easily operated whole and supports users' operations of programs through a consistent friendly and flexible interactive user interface. TAE also supplies the interface between the user and the various application programs in a particular computer system. It appears to be an effective user interface for infrequent as well as for expert users.

Gill, Esther Naomi↗
NASA NTRS1988

Investigation of surface tension driven convection as a feasibility study for a micro-gravity experiment

The work performed for the feasibility study of a microgravity surface tension driven convection experiment was reviewed. An experimental investigation of the onset of convection in shallow fluid layers heated uniformly from below and cooled from above by an air layer was made. Results are discussed in relation to the formation of Benard cells. The onset of Rayleigh-Benard convection in thin fluid layers heated uniformly from below were studied experimentally. It was found that in thin fluid layers the onset of Rayleigh-Benard convection is preceded by subcritical convective motions. Secondly, it was found that the onset of Rayleigh-Benard convection in non-Boussinesq fluid layers takes place in the form of hexagonal cells at Rayleigh numbers larger than the critical Rayleigh number R sub C = 1708 which determines the onset of convection in Boussinesq fluid layers.

Koschmieder, E. L.↗
NASA NTRS1987

The space station assembly phase: Flight telerobotic servicer feasibility. Volume 2: Methodology and case study

A methodology is described for examining the feasibility of a Flight Telerobotic Servicer (FTS) using two assembly scenarios, defined at the EVA task level, for the 30 shuttle flights (beginning with MB-1) over a four-year period. Performing all EVA tasks by crew only is compared to a scenario in which crew EVA is augmented by FTS. A reference FTS concept is used as a technology baseline and life-cycle cost analysis is performed to highlight cost tradeoffs. The methodology, procedure, and data used to complete the analysis are documented in detail.

Smith, Jeffrey H.↗
NASA NTRS1988

Program for the feasibility of developing a high pressure acoustic levitator

This is the final report for the program for the feasibility of developing a high-pressure acoustic levitator (HPAL). It includes work performed during the period from February 15, 1987 to October 26, 1987. The program was conducted for NASA under contract number NAS3-25115. The HPAL would be used for containerless processing of materials in the 1-g Earth environment. Results show that the use of increased gas pressure produces higher sound pressure levels. The harmonics produced by the acoustic source are also reduced. This provides an improvement in the capabilities of acoustic levitation in 1-g. The reported processing capabilities are directly limited by the design of the Medium Pressure Acoustic Levitator used for this study. Data show that sufficient acoustic intensities can be obtained to levitate and process a specimen of density 5 g/cu cm at 1500 C. However, it is recommended that a working engineering model of the HPAL be developed. The model would be used to establish the maximum operating parameters of furnace temperature and sample density.

Rey, Charles A.↗
NASA NTRS1988

The Feasibility of the Disturbance Accommodating Controller for Precision Antenna Pointing

The objective of this study is to investigate the feasibility of a pointing (position loop) controller for the NASA-JPL Deep Space Network (DSN) antennas using the Disturbance Accommodating Control (DAC) theory. A model that includes state dependent disturbances was developed, and an example demonstrating the noise estimator is presented as an initial phase in the controller design. The goal is to improve pointing accuracy by the removal of the systematic errors caused by the antenna misalignment as well as sensor noise and random wind and thermal disturbances. Preliminary simulation results show that the DAC technique is successful in both cancelling the imposed errors and maintaining an optimal control policy.

Gresham, L. L.↗
NASA NTRS1986

SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 2. Appendix A: Design study for a SLEEC actuation system

The results are presented of a design feasibility study of a self-contained (powered) actuation system for a Shingle Lap Extendible Exit Cone (SLEEC) for Transportation System (STS). The evolution of the SLEEC actuation system design is reviewed, the final design concept is summarized, and the results of the detailed study of the final concept of the actuation system are treated. A conservative design using proven mechanical components was established as a major program priority. The final mechanical design has a very low development risk since the components, which consist of ballscrews, gearing, flexible shaft drives, and aircraft cables, have extensive aerospace applications and a history of proven reliability. The mathematical model studies have shown that little or no power is required to deploy the SLEEC actuation system because acceleration forces and internal pressure from the rocket plume provide the required energies. A speed control brake is incorporated in the design in order to control the rate of deployment.

Thompson, D. S.↗
NASA NTRS1987

Atmospheric Science Field Laboratory - A feasibility study

Plans are underway to transfer the technology represented by the lightning and atmospheric science research facilities and capabilities at the Kennedy Space Center to outside users in other government agencies, private industry, and the academic community. Rocket triggered lightning is being used to demonstrate the feasibility of establishing an Atmospheric Science Field Laboratory as a permanent facility and long-term cost sharing. Results from previous programs and data from a lightning event which occurred during the STS-7 flight are presented to demonstrate the adequacy of the present lightning protection and measuring system to protect personnel, vehicle, and ground equipment, as well as to rapidly assess damage due to a lightning event.

Jafferis, William↗