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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Wind tunnel acoustic study of a propeller installed behind an airplane empennage: Data report

The open test section of the NASA-Ames 7- by 10- ft wind tunnel was used for an acoustic test of a propeller mounted behind an airplane empennage. The empennage was attached to a model fuselage and the propeller with its electric motor drive was mounted separately so that the relative positions of empennage and propeller could be varied. A single vertical fin, and a V-tail with, and without, a dorsal fin configurations were used the model propeller had four blades (SR-1). Data were recorded at several locations for two tunnel flow speeds (45.7) and 62.5 m/s) and propeller speeds in the range 4000 to 8200 rpm. Data reduction was performed in narrowband and one-third octave band spectra, with emphasis on harmonics of the passage frequency blade. The influence of flow speed, propeller rpm, empennage configuration, axial and vertical separation between propeller axis and empennage centerline, and empennage angle of incidence on propeller harmonic levels and acoustic field directivity are studied.

Wilby, J. F.↗
NASA NTRS1978

Analysis and Test of Deep Flaws in Thin Sheets of Aluminum and Titanium. Volume 2: Crack Opening Displacement and Stress-Strain Data

Static fracture tests were performed on surface flawed specimens of aluminum and titanium alloys. A simulated proof overload cycle was applied prior to all of the cyclic tests. Variables included in each test series were flaw shapes and thickness. Additionally, test temperature was a variable for the aluminum test series. The crack opening displacement and stress-strain data obtained are presented.

Finger, R. W.↗
NASA NTRS1986

Real-time open-loop frequency response analysis of flight test data

A technique has been developed to compare the open-loop frequency response of a flight test aircraft real time with linear analysis predictions. The result is direct feedback to the flight control systems engineer on the validity of predictions and adds confidence for proceeding with envelope expansion. Further, gain and phase margins can be tracked for trends in a manner similar to the techniques used by structural dynamics engineers in tracking structural modal damping.

Bosworth, J. T.↗
NASA NTRS1984

Method to estimate drag coefficient at the air/ice interface over drifting open pack ice from remotely sensed data

A knowledge in near real time, of the surface drag coefficient for drifting pack ice is vital for predicting its motions. And since this is not routinely available from measurements it must be replaced by estimates. Hence, a method for estimating this variable, as well as the drag coefficient at the water/ice interface and the ice thickness, for drifting open pack ice was developed. These estimates were derived from three-day sequences of LANDSAT-1 MSS images and surface weather charts and from the observed minima and maxima of these variables. The method was tested with four data sets in the southeastern Beaufort sea. Acceptable results were obtained for three data sets. Routine application of the method depends on the availability of data from an all-weather air or spaceborne remote sensing system, producing images with high geometric fidelity and high resolution.

Feldman, U.↗
NASA NTRS1986

Galileo Li/SO sub 2 battery modules program update

In order to meet the power needs of NASA's Galileo Probe, the Li/SO2 high rate D cells used in the battery modules have undergone some design changes, as upgrading of hardware quality requirements, and significant testing. A description of the design changes and the cell test data that are of a general nature is presented here. This data includes capacities, open circuit voltages, and internal resistance comparisons. A significant data base was built up over the years and continues to grow.

Smith, R. A.↗
NASA NTRS1984

A review and analysis of boundary layer transition data for turbine application

A symposium on transition in turbines was held at the NASA Lewis Research Center. One recommendation of the working groups was the collection of existing transition data to provide standard cases against which models could be tested. A number of data sets from the open literature that include heat transfer data in apparently transitional boundary layers, with particular application to the turbine environment, were reviewed and analyzed to extract transition information from the heat transfer data. The data sets reviewed cover a wide range of flow conditions, from low speed, flat plate tests to full scale turbine airfoils operating at simulated turbine engine conditions. The results indicate that free stream turbulence and pressure gradient have strong, and opposite, effects on the location of the start of transition and on the length of the transition zone.

Gaugler, R. E.↗
NASA NTRS1985

A review and analysis of boundary layer transition data for turbine application

A number of data sets from the open literature that include heat transfer data in apparently transitional boundary layers, with particular application to the turbine environment, were reviewed and analyzed to extract transition information. The data were analyzed by using a version of the STAN5 two-dimensional boundary layer code. The transition starting and ending points were determined by adjusting parameters in STAN5 until the calculations matched the data. The results are presented as a table of the deduced transition location and length as functions of the test parameters. The data sets reviewed cover a wide range of flow conditions, from low-speed, flat-plate tests to full-scale turbine airfoils operating at simulated turbine engine conditions. The results indicate that free-stream turbulence and pressure gradient have strong, and opposite, effects on the location of the start of transition and on the length of the transition zone.

Gaugler, R. E.↗
NASA NTRS1985

A review and analysis of boundary layer transition data for turbine application

A symposium on transition in turbines was held at the NASA Lewis Research Center. One recommendation of the working groups was the collection of existing transition data to provide standard cases against which models could be tested. A number of data sets from the open literature that include heat transfer data in apparently transitional boundary layers, with particular application to the turbine environment, were reviewed and analyzed to extract transition information from the heat transfer data. The data sets reviewed cover a wide range of flow conditions, from low speed, flat plate tests to full scale turbine airfoils operating at simulated turbine engine conditions. The results indicate that free stream turbulence and pressure gradient have strong, and opposite, effects on the location of the start of transition and on the length of the transition zone.

Gaugler, R. E.↗
NASA NTRS1987

Anomalous dust in the open cluster Trumpler 37

New IUE data were obtained towards stars in the open cluster Trumpler 37. Extinction curves derived from these data show that the anomalous dust detected towards HD 204827 and HD 210072 is not unique to those lines of sight but occurs generally in that region of the sky. The dust is apparently associated with the Trumpler 37 cluster, which forms the center of Cepheus OB2. This is a complex region of star formation where the evolution of dust grains through shock waves could be considered likely. A supernova in a slightly older star-forming region of Cep OB2 located next to Trumpler 37 is a possible source of such a shock wave.

Clayton, Geoffrey C.↗
NASA NTRS1971

A note on the effect of reflected solar radiation on airborne and ground measurements in the thermal infrared

The magnitude of thermal solar radiation reflected from water surfaces is considered. It is shown both theoretically and by field observation that, for instruments with small fields of view, the reflected thermal solar radiation can contribute significantly to the measured energy. Comparison of thermal scanner data taken from aircraft at a 16 deg azimuth angle from the mirror point of the sun over the open ocean with data taken at a 164 deg anzimuth angle from the mirror point of the sun at the same angle from nadir is indicative of a difference of 2.8 K in the equivalent black body radiation temperature. Observations taken from a surface vessel into sunglint 80 deg from nadir are indicative of an equivalent black body radiation temperature that is 34 K warmer than the temperature obtained at a similar nadir angle away from the sunglint.

Whitehead, V. S.↗
NASA NTRS1986

Aerodynamics of seeing on large transport aircraft

Data were obtained in the full scale flight environment of the Kuiper Airborne Observatory (KAO) on the nature of turbulent shear layer over the open cavity. These data were used to verify proposed aerodynamic scaling relationships to describe the behavior of the turbulent layers and to estimate the optical performance of systems of various wavelengths operating within the KAO environment. These data and wind tunnel data are used to scale the expected optical effects for a potential stratospheric observatory for infrared astronomy (SOFIA) in which a telescope approximately 3.5 times larger than that on the KAO is envisioned. It appears that the use of combinations of active and passive aeromechanical flow control techniques can improve the optical behavior of systems in the SOFIA environment. Experiments to verify these potential improvements can be performed on the KAO with sufficient modifications to the cavity and aero-mechanical technique installations.

Rose, W. C.↗
NASA NTRS1986

Significance of the Sm-Nd isotopic systematics of the Akilia Association

Samarium-Neodymium analyses were carried out on fourteen samples of basic to ultrabasic metavolcanics from several enclaves of the Amitsoq gneisses (T = to or approximately 3,700 Ma). Field observations suggest that all the analyzed rocks belong to the pre-Amitsoq Akilia Association. Consequently, a minimum age of 3,700 Ma is postulated for the emplacement of their protoliths. When all the data points are put together in a conventional isochron diagram, no clear isochron relationship can be discerned. However, the points seem to fall within a band broadly corresponding to an age of 3,600 Ma. The isotopic results are difficult to interpret satisfactorily. Two contrasting interpretations are offered and summarized: (1) data scatter as a result of open system behavior; and (2) data scatter due to a melange of data sets defining two distinct isochrons.

Gruau, G.↗
NASA NTRS1978

Data Requirements for Oceanic Processes in the Open Ocean, Coastal Zone, and Cryosphere

The type of information system that is needed to meet the requirements of ocean, coastal, and polar region users was examined. The requisite qualities of the system are: (1) availability, (2) accessibility, (3) responsiveness, (4) utility, (5) continuity, and (6) NASA participation. The system would not displace existing capabilities, but would have to integrate and expand the capabilities of existing systems and resolve the deficiencies that currently exist in producer-to-user information delivery options.

Nagler, R. G.↗
NASA NTRS1980

Refraction and scattering of sound by a shear layer

The angle and amplitude changes for acoustic waves refracted by a circular open jet shear layer were determined. The generalized refraction theory was assessed experimentally for on axis and off axis acoustic source locations as source frequency varied from 1 kHz to 10 kHz and free stream Mach number varied from 0.1 to 0.4. Angle and amplitude changes across the shear layer show good agreement with theory. Experiments confirm that the refraction theory is independent of shear layer thickness, acoustic source frequency, and source type. A generalized theory is, thus, available for correcting far field noise data acquired in open jet test facilities. The effect of discrete tone scattering by the open jet turbulent shear layer was also studied. Scattering effects were investigated over the same Mach number range as frequency varied from 5 kHz to 15 kHz. Attenuation of discrete tone amplitude and tone broadening were measured as a function of acoustic source position and radiation angle. Scattering was found to be stronger at angles close to the open jet axis than at 90 deg, and becomes stronger as the acoustic source position shifts downstream. A scattering analysis provided an estimate of the onset of discrete tone scattering.

Schlinker, R. H.↗
NASA NTRS1979

Scale covariance and G-varying cosmology. III - The /m, z/, /theta sub m, z/, /theta sub i, z/, and /N/m/, m/ tests

The Einstein gravitational equations in atomic units are fully solved for a matter-dominated universe in the context of a recently proposed scale-covariant cosmology. The magnitude-redshift relation for elliptical galaxies is studied, the evolutionary parameter used in such a study is derived, and the relation between isophotal angular diameters and redshifts is investigated, along with the relation between metric angular diameters and redshifts, the N(m)-magnitude relation for QSOs, and the magnitude-redshift relation for QSOs. Results are presented for four gauges (i.e., relations between G and the scale function beta (t)), and no contradictions are found between the proposed theory and the observational data. It is shown that only an open universe can fit the data if certain gauges suggested by a recent analysis of the time variation of the moon's period are selected and that observations made with atomic instruments do not necessarily yield geometrical parameters unless specific assumptions are made regarding the relation between atomic and gravitational dynamics.

Canuto, V. M.↗
NASA NTRS1972

Characteristics of hingeless rotors with hub moment feedback controls including experimental rotor frequency response, Volume 1

Wind tunnel tests to determine the dynamic characteristics of hingeless rotors with hub moment feedback controls and to acquire experimental hingeless rotor transfer functions are discussed. Rotor transfer functions were calculated from data acquired during open loop frequency response tests. The transfer functions are linear and present the rotor longitudinal and lateral frequency responses to collective pitch, longitudinal cyclic pitch, and lateral cyclic pitch. The theoretical analysis was based on the rigid blade flapping model coupled with appropriate control system and cyclic pitch actuator equations of motion.

Kuczynski, W. A.↗
NASA NTRS1976

Optically relevant turbulence parameters in the Marine boundary layer

Shipboard measurements of temperature and velocity fluctuations were performed to determine optical propagation properties of the marine boundary layer. Empirical expressions describing the temperature structure parameter in terms of the Richardson Number overland were used to analyze data obtained for open ocean conditions. Likewise, profiles of mean wind and velocity fluctuation spectra derived from shipboard observations were utilized to calculate associated boundary layer turbulence parameters. In general, there are considerable differences between the open-ocean results of this study and previously determined overland results.

Davidson, K. L.↗