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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Computational Study of Modeling Fully-Coupled Combustor-Turbine Interactions by the Open National Combustion Code (OpenNCC)

In this study, preliminary results are presented from the Open National Combustion Code (OpenNCC) applied to the two-stage high-pressure turbine (HTP) from the energy efficient engine (E3) program. Although the combustor is designed for efficient fuel–air mixing and a relatively uniform exit temperature profile, temporal and spatial variation in combustor exit conditions inevitably lead to hot-streaks in the HPT. These hot streaks can cause local hot spots on the HPT blade surfaces that reduce blade life. To improve understanding of these effects and the overall design of combustor and HPT, we proposed a sequential approach: Step 1 (combustor _ 1st stage stator), Step 2 (HPT) and Step 3 (fully-coupled EEE combustor/HPT). In this presentation, we would like to discuss the recent numerical results at two different operating conditions: the simulated Sea-Level Take-off (SLTO) condition (P41 = 2.4 [atm]) and a more realistic SLTO (P41 = 27.4 [atm])).

LES↗
NASA NTRS2016

The UK Met Office GCM with a Sophisticated Radiation Scheme Applied to the Hot Jupiter HD 209458b

To study the complexity of hot Jupiter atmospheres revealed by observations of increasing quality, we have adapted the UK Met Office Global Circulation Model (GCM), the Unified Model (UM), to these exoplanets. The UM solves the full 3D Navier-Stokes equations with a height-varying gravity, avoiding the simplifications used in most GCMs currently applied to exoplanets. In this work we present the coupling of the UM dynamical core to an accurate radiation scheme based on the two-stream approximation and correlated-k method with state-of-the-art opacities from ExoMol. Our first application of this model is devoted to the extensively studied hot Jupiter HD 209458b. We derive synthetic emission spectra and phase curves, and compare them to both previous models also based on state-of-the-art radiative transfer, and to observations. We find a reasonable a agreement between observations and both our days side emission and hot spot offset, however, our night side emissions is too large. Overall our results are qualitatively similar to those found by Showman et al. (2009) with the SPARCMIT gcm, however, we note several quantitative differences: Our simulations show significant variation in the position of the hottest part of the atmosphere with pressure, as expected from simple timescale arguments, and in contrast to the vertical coherency found by Showman et al. (2009). We also see significant quantitative differences in calculated synthetic observations. Our comparisons strengthen the need for detailed intercomparisons of dynamical cores, radiation schemes and post-processing tools to understand these differences. This effort is necessary in order to make robust conclusions about these atmospheres based on GCM results.

radiation↗
NASA NTRS1966

Cold solid propellant motor has stop-restart capability

Solid propellant rocket is kept and fired at low temperatures in launch vehicles or spacecraft. The motor is capable of developing a specific impulse comparable to that of liquid propellant motors, is started, stopped, and restarted, and is stored in space without solar radiation causing hot spots on the motor casing.

Hendel, F. J.↗
NASA NTRS1968

Silicon solar cell monitors high temperature furnace operation

Silicon solar cell, attached to each viewpoint, monitors that incandescent emission from the hot interior of a furnace without interfering with the test assembly or optical pyrometry during the test. This technique can provide continuous indication of hot spots or provide warning of excessive temperatures in cooler regions.

Zellner, G. J.↗
NASA NTRS1969

Lunar geophysics.

Seismic regions location prediction on visible lunar side based on transient events, hot spots and gravity anomalies

Simmons, G.↗
NASA NTRS1971

Methods of measurement for semiconductor materials, process control, and devices

The development of methods of measurement for semiconductor materials, process control, and devices is discussed. The following subjects are also presented: (1) demonstration of the high sensitivity of the infrared response technique by the identification of gold in a germanium diode, (2) verification that transient thermal response is significantly more sensitive to the presence of voids in die attachment than steady-state thermal resistance, and (3) development of equipment for determining susceptibility of transistors to hot spot formation by the current-gain technique.

Bullis, W. M.↗
NASA NTRS1971

Infrared observations of the core of Centaurus A, NGC 5128.

Infrared radiation from the nucleus of NGC 5128 has been measured from 1 to 10 microns. Scans and aperture-size data show that there is only one bright infrared region within the central 1 min of the galaxy and that it is coincident to within 5 sec with the ?hot spot' of Kunkel and Bradt. The 3.5- and 2.2-micron radiation is more peaked toward the center than are the shorter wavelengths. The data are interpreted to indicate a small nonstellar infrared core superposed on an extended, reddened stellar component.

Becklin, E. E.↗
NASA NTRS1972

Solar Array System for the Skylab Orbital Workshop.

The Solar Array System for the Skylab Orbital Workshop is designed to supply average power to power-conditioning equipment of 10496 watts while oriented toward the sun during the sunlit portion of each orbit. This paper discusses the operating voltage of the arrays over the expected temperature range, temperature cycling effects on both cell interconnects and cells, and overall effects of hot spots induced by shadows cast on the arrays by elements of the spacecraft.

North, N. B.↗
NASA NTRS1973

Radon emanation from the moon - Spatial and temporal variability.

Observations of Rn-222 and Po-210 on the lunar surface with the orbiting Apollo alpha particle spectrometer reveal a number of features in their spatial distribution and indicate the existence of time variations in lunar radon emission. Localized Rn-222 or Po-210 around the craters Aristarchus and Grimaldi and the edges of virtually all maria indicates time varying radon emission and suggests a correlation between alpha 'hot spots' and sites of transient optical events observed from the earth. In a gross sense, the slower variations of Rn-222 seem to correlate with the distribution of gamma activity.

Gorenstein, P.↗
NASA NTRS1974

Preliminary results of the Apollo 17 infrared scanning radiometer

The thermal emission of the lunar surface has been mapped by an infrared scanner from lunar orbit. Samples from approximately 250,000 scans reveal the full range of lunar temperatures from 80 to 400 K. The temperature resolution was 1 K with about plus or minus 2 K absolute precision. Spatial resolution was approximately 2 km over most of the horizon-to-horizon scan. The total mapped area amounted to approximately 30% of the lunar surface. The data currently available confirms the large population of nighttime thermal anomalies in western Oceanus Procellarum predicted by earth-based observations. Most of these 'hot spots' are associated with fresh impact features or boulder fields. Also seen in the data are 'cold spots' where the local nighttime temperature is depressed relative to the general soil background. Such regions exhibiting low surface conductivity are inferred to be relatively young, nonimpact features.

Mendell, W. W.↗
NASA NTRS1974

Nonperiodic optical flickering in HZ Herculis

High-speed simultaneous dual-channel photometry of HZ Her and a nearby comparison star reveal nonperiodic optical flickering in the HZ Her system on a time scale of 15 to 300 sec. The amplitude of the flickering appears to be correlated with orbital phase. Optical emission from a hot spot in a disk of material around the X-ray source cannot account for the flickering.

Moffett, T. J.↗
NASA NTRS1974

Contribution of space platforms to a ground and airborne remote-sensing programme over active Italian volcanoes

ERTS-1 imagery of the volcanic areas of southern Italy was used primarily for the evaluation of space platform capabilties in the domains of regional geology, soil and rock-type classification and, more generally, to study the environment of active volcanoes. The test sites were selected and equipped primarily to monitor thermal emission, but ground truth data was also collected in other domains (reflectance of rocks, soils and vegetation). The test areas were overflown with a two channel thermal scanner, while a thermo camera was used on the ground to monitor the hot spots. The primary goal of this survey was to plot the changes in thermal emission with time in the framework of a research program for the surveillance of active volcanoes. However, another task was an evaluation of emissivity changes by comparing the outputs of the two thermal channels. These results were compared with the reflectance changes observed on multispectral ERTS-1 imagery.

Cassinis, R.↗
NASA NTRS1974

Analysis of Skylab MSS data, and calibration of thermal data over Lake Monroe, Indiana

The author has identified the following significant results. The SL/4-S192 data over northern Indiana looks good. The thermal band looks very encouraging. The preliminary analysis indicates so far that it will be difficult to distinguish some land use classes because of the lack of vegetation. Preliminary analysis of the thermal band in particular indicates that there appears to be a correlation of the hot spots in the data over the Ft. Wayne, Indiana area and its industrial centers.

Silva, L. F.↗
NASA NTRS1975

Absolute plate motions by boundary velocity minimizations

The main interaction of the earth's interior with the lithosphere is as a material source and sink. An absolute reference frame defined by minimizing the translational motion of tectonic plate boundaries differs by 0.6 cm/year from a frame defined by hot spot traces and by 0.4 cm/year from the frame defined by the most plausible model of drag forces on the plates. The rms absolute translational velocities are about 2 cm/year for ocean-ocean plate boundaries and 1.5 cm/year for ocean-continent plate boundaries. The close agreement between the source and sink and the drag-dependent definitions suggests that the lithosphere, as a stress guide, to some extent controls the locations of its sources and sinks.

Kaula, W. M.↗
NASA NTRS1975

Detection of water vapor on Jupiter

High-altitude (12.4 km) spectroscopic observations of Jupiter at 5 microns from the NASA 91.5 cm airborne infrared telescope have revealed 14 absorptions assigned to the rotation-vibration spectrum of water vapor. Preliminary analysis indicates a mixing ratio about 1 millionth for the vapor phase of water. Estimates of temperature (greater than about 300 K) and pressure (less than 20 atm) suggest observation of water deep in Jupiter's hot spots responsible for its 5 micron flux. Model-atmosphere calculations based on radiative-transfer theory may change these initial estimates and provide a better physical picture of Jupiter's atmosphere below the visible cloud tops.

Larson, H. P.↗
NASA NTRS1975

Detectability of geothermal areas using Skylab X-5 data

The results are presented of a study which was undertaken to determine if data from a single near-noon pass of Skylab could be used to detect geothermal areas. The size and temperature requirements for a geothermally heated area to be seen by Skylab S-192 MSS X-5 thermal sensor were calculated. This sensor obtained thermal data with the highest spatial resolution of any nonmilitary satellite system. Only very large hot areas could be expected to be unambiguously recognized with a single data set from this instrument. The study area chosen was The Geysers geothermal field in Sonoma County, California, the only geothermal area of significant size scanned by Skylab. Unfortunately, 95% of the Skylab thermal channel data was acquired within 3 hours of local noon. For The Geysers area only daytime X-5 data were available. An analysis of the thermal channel data (10.2 to 12.5 um) revealed that ground temperatures determined by Skylab were normally distributed. No anomalous hot spots were apparent. Computer enhancement techniques were used to delineate the hottest 100 and 300 ground areas (pixel, 75 m by 75 m) within the study region. It was found that the Skylab MSS with the X-5 thermal detector does not have sufficient spatial resolution to locate unambiguously from daytime data any but the largest and hottest convectively created geothermal features, which in general are prominent enough to have been previously recognized.

Siegal, B. S.↗