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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

The feasibility of using time-dependent photochemical calculations to infer radical species concentrations from solar occultation absorption measurements

In connection with fast chemical reactions, short-lived stratospheric species experience rapid concentration variations at sunset and sunrise. For solar occultation absorption measurements, these rapid concentration variations may introduce significant errors with respect to the inference of atmospheric abundances for some species due to asymmetrical concentration distributions. Most retrieval algorithms assume that concentration distributions are spherically symmetric. The effect of this assumption on the accuracy of inferred concentrations has been studied by Kerr et al. (1977). The present investigation considers the feasibility of using a time-dependent one-dimensional photochemical model to provide detailed information about the asymmetrical distribution for use in the retrieval procedure. As shown by Boughner et al. (1980), diurnal effects can be represented by an inhomogeneity factor. It is found that the NO retrieval improves considerably with the inclusion of a correction factor containing the asymmetrical variations.

Larsen, J. C.↗
NASA NTRS1982

A study of the feasibility of statistical analysis of airport performance simulation

The feasibility of conducting a statistical analysis of simulation experiments to study airport capacity is investigated. First, the form of the distribution of airport capacity is studied. Since the distribution is non-Gaussian, it is important to determine the effect of this distribution on standard analysis of variance techniques and power calculations. Next, power computations are made in order to determine how economic simulation experiments would be if they are designed to detect capacity changes from condition to condition. Many of the conclusions drawn are results of Monte-Carlo techniques.

Myers, R. H.↗
NASA NTRS1981

Feasibility study of the solar scientific instruments for Spacelab/Orbiter

The feasibility and economics of mounting and operating a set of solar scientific instruments in the backup Skylab Apollo Telescope Mount (ATM) hardware was evaluated. The instruments used as the study test payload and integrated into the ATM were: the Solar EUV Telescope/Spectrometer; the Solar Active Region Observing Telescope; and the Lyman Alpha White Light Coronagraph. The backup ATM hardware consists of a central cruciform structure, called the "SPAR', a "Sun End Canister' and a "Multiple Docking Adapter End Canister'. Basically, the ATM hardware and software provides a structural interface for the instruments; a closely controlled thermal environment; and a very accurate attitude and pointing control capability. The hardware is an identical set to the hardware that flow on Skylab.

Leritz, J.↗
NASA NTRS1983

Experimental feasibility study of a thermoelectric heat flux gage

An experiment was conducted to determine the feasibility of using a commercially available thermoelectric device as a heat flux gage at near ambient conditions. In certain research applications, the thermoelectric heat flux gage can provide a relatively simple means to model a warm fluid cold wall convection environment. The experiment showed that heat flux through the gage could be correlated within 2.5 percent with a simple algebraic equation which considered the thermoelectric current through the device and the hot and cold side temperatures.

Vanfossen, G. J.↗
NASA NTRS1982

Design and feasibility study for a portable oil recovery turbopump

A portable oil recovery turbopump concept, using the Firefly module as primer mover, for the offloading of distressed tank vessels is examined. The demands to be met both in terms of the type of petroleum to be offloaded, as well as the operational requirements placed on the pump, are studied with respect to the capability of different pump configurations. Two configurations, one a centrifugal type and the other a screw type pump, are developed and evaluated. While the centrifugal configuration is found to be effective in a large proportion of tank vessel offloading situations, the screw type will be required where high viscosity cargoes are involved. The feasibility of the turbopump concept, with the Firefly module as prime mover, is established.

Source record↗
NASA NTRS1981

Modeling a beaver population on the Prescott Peninsula, Massachusetts: Feasibility of LANDSAT as an input

A preliminary dynamic model of beaver spatial distribution and population growth was developed. The feasibility of locating beaver ponds on LANDSAT digital tapes, and of using this information to provide initial conditions of beaver spatial distribution for the model, and to validate model predictions is discussed. The techniques used to identify beaver ponds on LANDSAT are described.

Finn, J. T.↗
NASA NTRS1983

CARS temperature measurements in the fuel preburner of the Space Shuttle main engine: A feasibility study

This report discusses the feasibility of making temperature profile measurements in the fuel preburner of the main engine of the space shuttle (SSME) using coherent anti-Stokes Raman spectroscopy (CARS). The principal thrust of the work is to identify problems associated with making CARS measurements in high temperature gas phase hydrogen at very high pressures (approx 400 atmospheres). To this end a theoretical study was made of the characteristics of the CAR spectra of H2 as a function of temperature and pressure and the accuracy with which temperatures can be extracted from this spectra. In addition the experimental problems associated with carrying out these measurements on a SSME at NSTL were identified. A conceptual design of a CARS system suitable for this work is included. Many of the results of the calculations made in this report are plotted as a function of temperature. In the course of presenting these results, it was necessary to decide whether the number of density or the pressure should be treated as a fixed parameter.

Beiting, E. J.↗
NASA NTRS1982

Laser system for natural gas detection. Phase 1: Laboratory feasibility studies

This project demonstrated the feasibility of using laser remote sensing technology as a tool for leak survey work in natural gas distribution systems. A laboratory device was assembled using a pair of helium neon (HeNe) lasers to measure methane. One HeNe laser emits radiation at a wavelength of 3.3922 micrometers, which corresponds to a strong absorption feature of methane, while the other emits radiation at a wavelength of 3.3911 micrometers, which corresponds to a weak absorption by methane. As a particular area is scanned for leaks, the laser is pointed at convenient topographic targets within its operating range, about 25 m. A portion of the backscattered radiation is collected by a receiver and focused onto an indium antimonide (InSb) photodetector, cooled to 77K. Methane concentrations were determined from the differential absorption at the two wavelengths for the backscattered radiation.

Grant, W. B.↗
NASA NTRS1983

Investigation of the feasibility of temperature profiling optical diagnostics in the SSME fuel pre-burner

Results of an analytical investigation to determine the feasibility of temperature profiling in the space shuttle main engine (SSME) fuel preburner are presented. In this application it is desirable to measure temperature in the preburner combustor with a remote, nonintrusive optical technique. Several techniques using laser excitation were examined with a consideration of the constraints imposed by optical access in the fuel preburner and the problems associated with operation near the functioning space shuttle engine. The potential performance of practical diagnostic systems based on spontaneous Raman backscattering, laser induced fluorescence, and coherent anti-Stokes Raman spectroscopy were compared analytically. A system using collection of spontaneous Raman backscattering excited by a remotely located 5 to 10 watt laser propagated to the SSME through a small diameter optical fiber was selected as the best approach. Difficulties normally associated with Raman scattering: weak signal strength and interference due to background radiation are not expected to be problematic due to the very high density in this application, and the low flame luminosity expected in the fuel rich hydrogen oxygen flame.

Shirley, J. A.↗
NASA NTRS1983

Evaluation of feasibility of measuring EHD film thickness associated with cryogenic fluids

The feasibility of measuring elastohydrodynamic (EHD) films as formed with a cryogenic (LN2) fluid is evaluated. Modifications were made to an existing twin disk EHD apparatus to allow for disk lubrication with liquid nitrogen. This disk apparatus is equipped with an X-ray system for measuring the thickness of any lubricant film that is formed between the disks. Several film thickness experiments were conducted with the apparatus which indicate that good lubrication films are filmed with LN2. In addition to the film thickness studies, failure analyses of three bearings were conducted. The HPOTP turbine end bearings had experienced axial loads of 36,000 to 44,000 N (8,000 to 10,000 lb). High continuous radial loads were also experienced, which were most likely caused by thermal growth of the inner race. The resulting high internal loads caused race spalling and ball wear to occur.

Kannel, J. W.↗
NASA NTRS1983

Experimental feasibility of the airborne measurement of absolute oil fluorescence spectral conversion efficiency

Airborne lidar oil spill experiments carried out to determine the practicability of the AOFSCE (absolute oil fluorescence spectral conversion efficiency) computational model are described. The results reveal that the model is suitable over a considerable range of oil film thicknesses provided the fluorescence efficiency of the oil does not approach the minimum detection sensitivity limitations of the lidar system. Separate airborne lidar experiments to demonstrate measurement of the water column Raman conversion efficiency are also conducted to ascertain the ultimate feasibility of converting such relative oil fluorescence to absolute values. Whereas the AOFSCE model is seen as highly promising, further airborne water column Raman conversion efficiency experiments with improved temporal or depth-resolved waveform calibration and software deconvolution techniques are thought necessary for a final determination of suitability.

Hoge, F. E.↗
NASA NTRS1982

The feasibility of thermal inertia mapping for detection of perched water tables in semi-arid irrigated lands

The thermal inertia mapping remote sensing technique is evaluated as a potential method for delineating areas of shallow perched water tables and related salinization problems on a regional basis. This method for detecting shallow water tables is based on the existence of significant differences in soil thermal properties between wet and dry soil profiles. Ground observations were conducted at two different test sites in California along the flight line, with one site located in a perched water table area and the other site in a well drained area. Measurements were taken hourly during a four day period (two days before and two days after the flight) for variables such as radiometric, meteorologic, soil moisture and temperature profiles, and surface characteristics. Results indicate that it is not feasible using present apparent thermal inertia remote sensing techniques to reliably delineate regional patterns of very shallow water tables due to the complex environmental system. However, some features within specific fields which may be directly related to the local presence of shallow water tables, such as differences in evaporative cooling due to soil moisture effects between and within fields, can be detected using the thermal inertia technique.

Ezra, C. E.↗
NASA NTRS1983

The feasibility of water injection into the turbine coolant to permit gas turbine contingency power for helicopter application

It is pointed out that in certain emergency situations it may be desirable to obtain power from a helicopter engine at levels greater than the maximum rating. Yost (1976) has reported studies concerning methods of power augmentation in the one engine inoperative (OEI) case. It was found that a combination of water/alcohol injection into the inlet and overtemperature/overspeed could provide adequate emergency power. The present investigation is concerned with the results of a feasibility study which analytically investigated the maximum possible level of augmentation with constant gas generator turbine stress rupture life as a constraint. In the proposed scheme, the increased engine output is obtained by turbine overtemperature, however, the temperature of the compressor bleed air used for hot section cooling is lowered by injecting and evaporating water.

Van Fossen, G. J.↗
NASA NTRS1983

Feasibility of airborne detection of laser-induced fluorescence emissions from green terrestrial plants

The present investigation provides a demonstration of the feasibility of the airborne detection of the laser-induced fluorescence spectral emissions from living terrestrial grasses, shrubs, and trees using existing levels of lidar technology. Airborne studies were performed to ascertain system requirements necessary to detect laser-induced fluorescence from living terrestrial plants, to assess the practical acquisition of useful single-shot laser-induced fluorescence (LIF) waveforms over vegetative canopies, and to determine the comparative suitability of laser system, airborne platform, and terrestrial environmental parameters. The field experiment was conducted on May 3, 1982, over the northern portion of Wallops Island, VA. Attention is given to airborne lidar results and the description of laboratory investigations.

Hoge, F. E.↗
NASA NTRS1983

A Feasibility Study of Electromagnetic De-Spin System for Earth Orbiting Satellites

This investigation is a feasibility study of electromagnetic satellite de-spin systems based on induced eddy-currents in the satellite by an external dc magnetic field. Two concepts have been investigated: (1) one based on a large diameter coil positioned around the satellite such that the axis of the satellite rotation is in the plane of the coil; and (2) a magnet, either permanent or electromagnet, positioned close to the satellite by the orbiter RMS. A comparison is made of the two concepts by varying the appropriate parameters with a view to reduce the de-spin time to a reasonable value. Design parameters for the magnets and the coil are indicated.

Prasad K Kadaba↗
NASA NTRS1984

Temperature and humidity profiles in the atmosphere from spaceborne lasers: A feasibility study

Computer simulations of the differential absorption lidar technique in a space craft for the purpose of temperature and humidity profiling indicate: (1) Current technology applied to O2 and H2O lines in the .7 to .8 micrometers wavelength band gives sufficiently high signal-to-noise ratios (up to 50 for a single pulse pair) if backscattering by aerosol particles is high, i.e. profiling accurate to 2 K for temperature and 10% for humidity should be feasible within the turbid lower troposphere in 1 km layers and with an averaging over approximately 100 pulses. (2) The impact of short term fluctuations in aerosol particle concentration is too big for a one laser system. Only a two laser system firing at a time lag of about 1 millisecond can surmount these difficulties. (3) The finite width of the laser line and the quasi-random shift of this line introduce tolerable, partly systematic errors.

Grassl, H.↗
NASA NTRS1984

Determining soil moisture from geosynchronous satellite infrared data - A feasibility study

Numerical modelling results are reported from a pilot study investigating the feasibility of developing a technique for daily soil moisture measurement throughout the world, based on GOES infrared data. A detailed one-dimensional boundary layer-surface-soil model was used in order to determine which physical parameters observable from GOES are most sensitive to soil moisture, and which are most effected by seasonal changes, atmospheric effects and vegetation cover. The results of the sensitivity test show that the mid-morning differential of surface temperature with respect to absorbed solar radiation is optimally sensitive to soil moisture. A case study comparing model results with GOES infrared data confirms the sensitivity of this parameter to soil moisture and also confirms the applicability of the model to predicting area-averaged surface temperature changes. Model measurements of soil moisture are expected to be most accurate for dry or marginal agricultural areas where drought is common. Sources of error, including the advection of clouds, are examined and methods of minimizing error are discussed.

Wetzel, P. J.↗