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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 NTRSDate not supplied

Development and Validation of a High-Vacuum Thermal Conductivity Testbed for Aerospace Interface Materials

Spacecraft thermal margins depend on the temperature penalty of installed interfaces, yet catalog conductivity omits bondline thickness, mating surfaces, preload, and environment. The Testbed for Advanced Interface Materials in Vacuum (TAIMV) addresses this engineering-data gap by converting ambient/vacuum temperature fields from a four-coupon stack into quantities usable in spacecraft thermal models. Its 17-node steady-state model resolves axial conduction, parasitic fixture paths, grease-filled contact, radiation, and ambient convection. Four monolithic checks gave axial heat-rate ratios of 0.90–1.02, and Braycote calibration self-recovery gave 2.20% casewise mean absolute percentage error (MAPE) and 2.85% maximum difference. With transferable fixture terms frozen, Krytox LVP tested cross-material transfer against a manufacturer-derived external relation. The six Krytox cases gave 2.28% MAPE, 5.10% maximum difference, and full-field residual root-mean-square values of 0.553 °C ambient and 1.306 °C vacuum. Installed-joint resistance spanned 6.39–7.15 × 10⁻⁴ m²·K/W for Braycote and 4.09–4.49 × 10⁻⁴ m²·K/W for Krytox, corresponding to 2.33–6.66 K per modeled interface over the tested heat-flux range. TAIMV therefore supplies directly usable installed-joint resistance and conductance, plus apparent installed conductivity and explicitly model-conditioned grease conductivity/contact terms.

heat transfer↗
NASA NTRS1986

Studies and analyses of the Space Shuttle Main Engine: SSME failure data review, diagnostic survey and SSME diagnostic evaluation

The results of a review of the Space Shuttle Main Engine (SSME) failure data for the period 1980 through 1983 are presented. The data was collected, evaluated, and ranked according to procedures established during this study. A number of conclusions and recommendations are made based upon this failure data review. The results of a state-of-the-art diagnostic survey are also presented. This survey covered a broad range of diagnostic sensors and techniques and the findings were evaluated for application to the SSME. Finally, a discussion of the initial activities for the on-going SSME diagnostic evaluation is included.

Glover, R. C.↗
NASA NTRS1976

Flight effects on exhaust noise for turbojet and turbofan engines: Comparison of experimental data with prediction

It was demonstrated that static and in flight jet engine exhaust noise can be predicted with reasonable accuracy when the multiple source nature of the problem is taken into account. Jet mixing noise was predicted from the interim prediction method. Provisional methods of estimating internally generated noise and shock noise flight effects were used, based partly on existing prediction methods and partly on recent reported engine data.

Stone, J. R.↗
NASA NTRS1976

Flight effects on exhaust noise for turbojet and turbofan engines - Comparison of experimental data with prediction

Recent experiments on the effects of flight on jet engine exhaust noise have produced apparently conflicting results. Some of these results do not agree with projections based on classical jet noise theories nor with experimental results from model jet simulated flight tests. It has been shown that in some of the cases reported, the proper corrections were not made to account for the distributed nature of the jet noise sources. It is shown herein that the remaining discrepancies can be reconciled by considering the combined effects of jet-mixing noise, internally-generated engine exhaust noise, and shock noise. This paper demonstrates that static and in-flight jet engine exhaust noise can be predicted with reasonable accuracy when the multiple-source nature of the problem is taken into account. Jet-mixing noise is predicted from an improved version of the NASA interim prediction method. Provisional methods of estimating internally-generated noise and shock noise flight effects are used, based partly on existing prediction methods and partly on recently reported engine data.

Stone, J. R.↗
NASA NTRS2001

Engineering Documentation and Data Control

Mississippi Space Services (MSS) the facility services contractor for NASA's John C. Stennis Space Center (SSC), is utilizing technology to improve engineering documentation and data control. Two identified improvement areas, labor intensive documentation research and outdated drafting standards, were targeted as top priority. MSS selected AutoManager(R) WorkFlow from Cyco software to manage engineering documentation. The software is currently installed on over 150 desctops. The outdated SSC drafting standard was written for pre-CADD drafting methods, in other words, board drafting. Implementation of COTS software solutions to manage engineering documentation and update the drafting standard resulted in significant increases in productivity by reducing the time spent searching for documents.

Matteson, Michael J.↗
NASA NTRS1982

Evaluating software development by analysis of changes: The data from the software engineering laboratory

An effective data collection methodology for evaluating software development methodologies was applied to four different software development projects. Goals of the data collection included characterizing changes and errors, characterizing projects and programmers, identifying effective error detection and correction techniques, and investigating ripple effects. The data collected consisted of changes (including error corrections) made to the software after code was written and baselined, but before testing began. Data collection and validation were concurrent with software development. Changes reported were verified by interviews with programmers.

Source record↗
NASA NTRS1974

Apollo experience report: Data management for postflight engineering evaluation

The Apollo management of data for postflight engineering evaluation is described. The sources of Apollo telemetry data, the control of data processing by a single data team, the data techniques used to assist in evaluation of the large quantity of data, and the operation of the data team before the mission and during the evaluation phase are described. The techniques used to ensure the output of valid data and to determine areas in which data were of questionable quality are also included.

Foster, G. B., Jr.↗
NASA NTRS1996

Forced response testing of an axi-centrifugal turboshaft engine

Dynamic data from tests of a T55-L-712 engine are presented. Engine stall/surge data were analyzed using digital signal processing techniques. In addition, forced response testing (system identification studies) was done at various engine speeds. Forced response testing was done using eight jet ejectors approximately equally circumferentially spaced about the compressor front face. This paper presents some preliminary results for the ground idle (approximately 60% of design speed) point. Brief descriptions of the jet injection system, the test matrix, and analysis techniques used are presented. Results of these analyses indicate a substantial transfer of energy across the compressor first stage at some frequencies and that the ejectors are effective in modifying the local flow conditions in front of the first compressor stage.

Owen, A. Karl↗
NASA NTRS1996

Forced Response Testing of an Axi-Centrifugal Turboshaft Engine

Dynamic data from tests of a T55-L,712 engine are presented. Engine stall/surge data were analyzed using digital signal processing techniques. In addition, forced response testing (system identification studies) was done at various engine speeds. Forced response testing was done using eight jet ejectors approximately equally circumferentially spaced about the compressor front face. This paper presents some preliminary results for the ground idle (approximately 60% of design speed) point. Brief descriptions of the jet injection system, the test matrix, and analysis techniques used are presented. Results of these analyses indicate a substantial transfer of energy across the compressor first stage at some frequencies and that the ejectors are effective in modifying the local flow conditions in front of the first compressor stage.

Owen, A. Karl↗
NASA NTRS2000

Martian Surface Boundary Layer Characterization: Enabling Environmental Data for Science, Engineering and Human Exploration

For human or large robotic exploration of Mars, engineering devices such as power sources will be utilized that interact closely with the Martian environment. Heat sources for power production, for example, will use the low ambient temperature for efficient heat rejection. The Martian ambient, however, is highly variable, and will have a first order influence on the efficiency and operation of all large-scale equipment. Diurnal changes in temperature, for example, can vary the theoretical efficiency of power production by 15% and affect the choice of equipment, working fluids, and operating parameters. As part of the Mars Exploration program, missions must acquire the environmental data needed for design, operation and maintenance of engineering equipment including the transportation devices. The information should focus on the variability of the environment, and on the differences among locations including latitudes, altitudes, and seasons. This paper outlines some of the WHY's, WHAT's and WHERE's of the needed data, as well as some examples of how this data will be used. Environmental data for engineering design should be considered a priority in Mars Exploration planning. The Mars Thermal Environment Radiator Characterization (MTERC), and Dust Accumulation and Removal Technology (DART) experiments planned for early Mars landers are examples of information needed for even small robotic missions. Large missions will require proportionately more accurate data that encompass larger samples of the Martian surface conditions. In achieving this goal, the Mars Exploration program will also acquire primary data needed for understanding Martian weather, surface evolution, and ground-atmosphere interrelationships.

England, C.↗