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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Observations of directional gamma prime coarsening during engine operation

Two alloys, NASAIR 100 and a modified NASAIR 100 called Alloy 3, were run as turbine blades in an experimental ground-based Garrett TFE731 engine for up to 200 hours. The stress induced directional coarsening of gamma-prime (rafting) that developed during engine testing was analyzed and compared to previous research from laboratory tests. The blades were found to have formed a lamellar structure, the lamellae being normal to the centrifugal stress axis over much of the span. However, near the surfaces, the blades were found to have formed lamellae parallel to the centrifugal stress axis for certain cycles. Representative photomicrographs of the blades and the effects of stress and temperature on lamellae formation are shown.

Draper, S.↗
NASA NTRS1957

Results of turbojet engine operation tests using a 50-50 mixture of JP-4 and tributyl borate as the fuel

An experimental investigation was conducted on a centrifugal-type turbojet engine using a 50-50 mixture of tributyl borate and JP-4 as the fuel to determine the magnitude and the location of the boric oxide deposits in the engine as well as the effect of these deposits on the engine performance. Large deposits of boric acid formed in the combustor walls and on the turbine rotor and stator blades. The deposits had no effect on the engine thrust.

Schafer, Louis J , Jr↗
NASA NTRS1975

Effect of afterburner lights and inlet unstarts on a mixed compression inlet turbofan engine operating at Mach 2.5

Data are presented to show the response of an uncontrolled inlet to afterburner lightoff disturbances when a mixed-compression inlet is coupled to a turbofan engine. The results show a significant upstream shock excursion when the afterburner lights which is a result of the direct communication between the afterburner region and the inlet by means of the fan duct and fan stages. In addition results of a waveform analysis on the inlet pressure response to the afterburner light is presented. Inlet unstarts and their effect on operation of the propulsion system is also discussed.

Baumbick, R. J.↗
NASA NTRS1987

Observations of directional gamma prime coarsening during engine operation

Two alloys with negative mismatch parameters, NASAIR 100 and a modified NASAIR 100 called Alloy 3 were run as turbine blades in an experimental ground based Garret TFE731 engine for up to 200 hr. The directional coarsening of gamma prime (rafting) that developed during engine testing was analyzed and compared to previous research from laboratory tests. The blades were found to be rafted normal to the centrifugal stress axis over much of the span, but near the surfaces, the blades were found to be rafted parallel to the centrifugal stress axis for certain cycles. Representative photomicrographs of the blades and the effects of stress and temperature on raft formation are shown.

Draper, Susan L.↗
NASA NTRS1976

Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

Liebert, C. H.↗
NASA NTRS1953

Comparison of Theoretically and Experimentally Determined Effects of Oxide Coatings Supplied by Fuel Additives on Uncooled Turbine-blade Temperature During Transient Turbojet-engine Operation

An analysis was made to permit the calculation of the effectiveness of oxide coatings in retarding the transient heat flow into turbine blades when the combustion gas temperature of a turbojet engine is suddenly changed. The analysis is checked with experimental data obtained from a turbojet engine whose blades were coated with two different coating materials (silicon dioxide and boric oxide) by adding silicone oil and tributyl borate to the engine fuel. The very thin coatings (approximately 0.001 in.) that formed on the blades produced a negligible effect on the turbine-blade transient temperature response. With the analysis discussed here, it was possible to predict the turbine rotor-blade temperature response with a maximum error of 40 F.

PROTECTIVE COATINGS↗
NASA NTRS1995

Algorithm Helps Monitor Engine Operation

Real-Time Failure Control (RTFC) algorithm part of automated monitoring-and-shutdown system being developed to ensure safety and prevent major damage to equipment during ground tests of main engine of space shuttle. Includes redundant sensors, controller voting logic circuits, automatic safe-limit logic circuits, and conditional-decision logic circuits, all monitored by human technicians. Basic principles of system also applicable to stationary powerplants and other complex machinery systems.

Eckerling, Sherry J.↗
NASA NTRS1972

Analysis of the flow field generated near an aircraft engine operating in reverse thrust

A computer solution is developed to the exhaust gas reingestion problem for aircraft operating in the reverse thrust mode on a crosswind-free runway. The computer program determines the location of the inlet flow pattern, whether the exhaust efflux lies within the inlet flow pattern or not, and if so, the approximate time before the reversed flow reaches the engine inlet. The program is written so that the user is free to select discrete runway speeds or to study the entire aircraft deceleration process for both the far field and cross-ingestion problems. While developed with STOL applications in mind, the solution is equally applicable to conventional designs. The inlet and reversed jet flow fields involved in the problem are assumed to be noninteracting. The nacelle model used in determining the inlet flow field is generated using an iterative solution to the Neuman problem from potential flow theory while the reversed jet flow field is adapted using an empirical correlation from the literature. Sample results obtained using the program are included.

Ledwith, W. A., Jr.↗
NASA NTRS1991

Radiation dose estimates for typical piloted NTR lunar and Mars mission engine operations

The natural and manmade radiation environments to be encountered during lunar and Mars missions are qualitatively summarized. The computational methods available to characterize the radiation environment produced by an operating nuclear propulsion system are discussed. Mission profiles and vehicle configurations are presented for a typical all-propulsive, fully reusable lunar mission and for a typical all-propulsive Mars mission. Estimates of crew location biological doses are developed for all propulsive maneuvers. Post-shutdown dose rates near the nuclear engine are estimated at selected mission times.

Schnitzler, Bruce G.↗
NASA NTRS1999

An Evolvable Multi-Agent Approach to Space Operations Engineering

A complex system of spacecraft and ground tracking stations, as well as a constellation of satellites or spacecraft, has to be able to reliably withstand sudden environment changes, resource fluctuations, dynamic resource configuration, limited communication bandwidth, etc., while maintaining the consistency of the system as a whole.

Intelligent↗
NASA NTRS1972

Hot-salt stress-corrosion of titanium alloys as related to turbine engine operation.

Demonstration that the major variables influencing hot-salt stress-corrosion of titanium alloys are alloy processing conditions, heat-to-heat variations and composition, surface condition, and cyclic exposures. Under simulated compressor environmental conditions the commonly used 64 alloy is creep limited and not stress-corrosion limited. Cyclic exposures to stress-corrosion conditions are not as detrimental as continuous exposures for equivalent total times.

Gray, H. R.↗
NASA NTRS1975

Sonic boom results for a nominal mission 3B. Space Shuttle engineering and operations support, engineering systems analysis

The results obtained in the analysis of the effects of sonic boom overpressures at ground level for a nominal Mission 3B with the current baseline guidance are reported. These results are in the form of ground level overpressures generated along the groundtrack out to lateral cutoff from Mach 3.0-1.10 at 0.10 (tenth) Mach intervals. Preliminary trajectory constraints which will reduce excess sonic boom overpressures to approximately 2.0 PSF are included.

Source record↗