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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Mass ejection from the peculiar emission star R Aquarii

It is pointed out that the composite emission object R Aquarii embodies a number of characteristic properties which distinguish it from other peculiar emission stars. The visual spectrum indicates the presence of a cool Mira variable in close association with a hot unresolved ionizing source of radiation which appears to be responsible for the high excitation nebular emission observed. It has been suggested by Hubble (1943) and Baade (1944) that the distinguishing meniscus-shaped nebula was formed by a nova outburst which occurred about 600 years ago. Wallerstein and Greenstein (1980) reported the appearance of a new feature in R Aquarii which resembles a brilliant 'spike' or 'jet' protruding a distance approximately 7 arcsec from the central compact region. Attention is given to several models which have been considered to explain the emission feature.

Michalitsianos, A. G.↗
NASA NTRS2016

Nanostructure Neutron Converter Layer Development

Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

Park, Cheol↗
NASA NTRS2013

Apparatus and Methods for Mitigating Electromagnetic Emissions

Apparatus, methods, and other embodiments associated with mitigation of magnetic fields are described herein. In an embodiment, a method for mitigating an electromagnetic field includes positioning a mitigating coil around a linear alternator of linear motor so that the mitigating coil is coaxially located with an alternator coil; arranging the mitigating coil to generate a field to mitigate an electromagnetic field generated by the alternator coil; and passing an induced current from the alternator coil through the mitigating coil.

Geng, Steven M.↗
NASA NTRS2016

Apparatus and Methods for Mitigating Electromagnetic Emissions

Apparatus, methods, and other embodiments associated with mitigation of magnetic fields are described herein. In an embodiment, a method for mitigating an electromagnetic field includes positioning a mitigating coil around a linear alternator of linear motor so that the mitigating coil is coaxially located with an alternator coil; arranging the mitigating coil to generate a field to mitigate an electromagnetic field generated by the alternator coil; and passing an induced current from the alternator coil through the mitigating coil.

Geng, Steven M.↗
NASA NTRS2005

Optically Stimulated Electron Emission Contamination Monitor and Method

An apparatus and method for performing quality inspections on a test surface based on optically stimulated emission of electrons. In one embodiment, the apparatus comprises a device for producing optical radiation having a plurality of different spectrum lines, selecting at least one of the spectrum lines, and directing the selected spectrum line to the test surface, and circuitry for detecting a current of photoelectrons emitted from the test surface, generating a signal indicative of photoelectron current, and for indicating a condition of quality based on the generated signal indicative of the photoelectron current. In one embodiment, the method comprises producing optical radiation having a plurality of different spectrum lines, selecting at least one of the spectrum lines and directing the selected spectrum line to the test surface, detecting a current of photoelectrons emitted from the test surface and generating a signal indicative of photoelectron current, and indicating a condition of quality based on the generated signal indicative of the photoelectron current.

Christopher S Welch↗
NASA NTRS2012

Spectroscopic Chemical Analysis Methods and Apparatus

This invention relates to non-contact spectroscopic methods and apparatus for performing chemical analysis and the ideal wavelengths and sources needed for this analysis. It employs deep ultraviolet (200- to 300-nm spectral range) electron-beam-pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor lightemitting devices, and hollow cathode metal ion lasers. Three achieved goals for this innovation are to reduce the size (under 20 L), reduce the weight [under 100 lb (.45 kg)], and reduce the power consumption (under 100 W). This method can be used in microscope or macroscope to provide measurement of Raman and/or native fluorescence emission spectra either by point-by-point measurement, or by global imaging of emissions within specific ultraviolet spectral bands. In other embodiments, the method can be used in analytical instruments such as capillary electrophoresis, capillary electro-chromatography, high-performance liquid chromatography, flow cytometry, and related instruments for detection and identification of unknown analytes using a combination of native fluorescence and/or Raman spectroscopic methods. This design provides an electron-beampumped semiconductor radiation-producing method, or source, that can emit at a wavelength (or wavelengths) below 300 nm, e.g. in the deep ultraviolet between about 200 and 300 nm, and more preferably less than 260 nm. In some variations, the method is to produce incoherent radiation, while in other implementations it produces laser radiation. In some variations, this object is achieved by using an AlGaN emission medium, while in other implementations a diamond emission medium may be used. This instrument irradiates a sample with deep UV radiation, and then uses an improved filter for separating wavelengths to be detected. This provides a multi-stage analysis of the sample. To avoid the difficulties related to producing deep UV semiconductor sources, a pumping approach has been developed that uses ballistic electron beam injection directly into the active region of a wide bandgap semiconductor material.

Hug, William F.↗
NASA NTRS2014

Native Fluorescence Detection Methods and Detectors for Naphthalene and/or Other Volatile Organic Compound Vapors

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds have been identified as serious health hazards. This is especially true for personnel working with JP8 jet fuel and other fuels containing naphthalene as well as other hazardous volatile organic compounds (VOCs). Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to naphthalene or other hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined. The badges employ a new native fluorescence based detection method to identify and differentiate VOCs. The particular focus of some embodiments are the detection and identification of naphthalene while other embodiments are directed to detection and identification of other VOCs like aromatic hydrocarbons such as benzene, toluene, and xylene.

Hug, William F.↗
NASA NTRS2016

Native Fluorescence Detection Methods, Devices, and Systems for Organic Compounds

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds VOCs have been identified as serious health hazards. Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined.

Hug, William F.↗
NASA NTRS2018

Native Fluorescence Detection Methods, Devices, and Systems for Organic Compounds

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds VOCs have been identified as serious health hazards. Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined.

Hug, William F.↗
NASA NTRS1999

Assessing the Impact of Aircraft Emissions on the Stratosphere

For the past decade, the NASA Atmospheric Effects of Aviation Project (AEAP) has been the U.S. focal point for research on aircraft effects. In conjunction with U.S. basic research programs, AEAP and concurrent European research programs have driven remarkable progress reports released in 1999 [IPCC, 1999; Kawa et al., 1999]. The former report primarily focuses on aircraft effects in the upper troposphere, with some discussion on stratospheric impacts. The latter report focuses entirely on the stratosphere. The current status of research regarding aviation effects on stratospheric ozone and climate, as embodied by the findings of these reports, is reviewed. The following topics are addressed: Aircraft Emissions, Pollution Transport, Atmospheric Chemistry, Polar Processes, Climate Impacts of Supersonic Aircraft, Subsonic Aircraft Effect on the Stratosphere, Calculations of the Supersonic Impact on Ozone and Sensitivity to Input Conditions.

Kawa, S. R.↗
NASA NTRS1996

Microgravity Turbulent Gas-Jet Diffusion Flames

A gas-jet diffusion flame is similar to the flame on a Bunsen burner, where a gaseous fuel (e.g., propane) flows from a nozzle into an oxygen-containing atmosphere (e.g., air). The difference is that a Bunsen burner allows for (partial) premixing of the fuel and the air, whereas a diffusion flame is not premixed and gets its oxygen (principally) by diffusion from the atmosphere around the flame. Simple gas-jet diffusion flames are often used for combustion studies because they embody the mechanisms operating in accidental fires and in practical combustion systems. However, most practical combustion is turbulent (i.e., with random flow vortices), which enhances the fuel/air mixing. These turbulent flames are not well understood because their random and transient nature complicates analysis. Normal gravity studies of turbulence in gas-jet diffusion flames can be impeded by buoyancy-induced instabilities. These gravitycaused instabilities, which are evident in the flickering of a candle flame in normal gravity, interfere with the study of turbulent gas-jet diffusion flames. By conducting experiments in microgravity, where buoyant instabilities are avoided, we at the NASA Lewis Research Center hope to improve our understanding of turbulent combustion. Ultimately, this could lead to improvements in combustor design, yielding higher efficiency and lower pollutant emissions. Gas-jet diffusion flames are often researched as model flames, because they embody mechanisms operating in both accidental fires and practical combustion systems (see the first figure). In normal gravity laboratory research, buoyant air flows, which are often negligible in practical situations, dominate the heat and mass transfer processes. Microgravity research studies, however, are not constrained by buoyant air flows, and new, unique information on the behavior of gas-jet diffusion flames has been obtained.

Source record↗
NASA NTRS1980

A solar activity monitoring platform for SCADM

The adaptation of proven space probe technology is proposed as a means of providing a solar activity monitoring platform which could be injected behind the Earth's orbital position to give 3 to 6 days advanced coverage of the solar phenomenon on the backside hemisphere before it rotates into view and affects terrestrial activities. The probe would provide some three dimensional discrimination within the ecliptic latitude. This relatively simple off-Earth probe could provide very high quality data to support the SCADM program, by transmitting both high resolution video data of the solar surface and such measurements of solar activity as particle, X-ray, ultraviolet, and radio emission fluxes. Topics covered include the orbit; constraints on the spacecraft; subsystems and their embodiments; optical imaging sensors and their operation; and the radiation-pressure attitude control system are described. The platform would be capable of mapping active regions on an hourly basis with one arc-second resolution.

Kissell, K. E.↗
NASA NTRS2005

Predicting Noise From Aircraft Turbine-Engine Combustors

COMBUSTOR and CNOISE are computer codes that predict far-field noise that originates in the combustors of modern aircraft turbine engines -- especially modern, low-gaseous-emission engines, the combustors of which sometimes generate several decibels more noise than do the combustors of older turbine engines. COMBUSTOR implements an empirical model of combustor noise derived from correlations between engine-noise data and operational and geometric parameters, and was developed from databases of measurements of acoustic emissions of engines. CNOISE implements an analytical and computational model of the propagation of combustor temperature fluctuations (hot spots) through downstream turbine stages. Such hot spots are known to give rise to far-field noise. CNOISE is expected to be helpful in determining why low-emission combustors are sometimes noisier than older ones, to provide guidance for refining the empirical correlation model embodied in the COMBUSTOR code, and to provide insight on how to vary downstream turbinestage geometry to reduce the contribution of hot spots to far-field noise.

Gliebe, P.↗
NASA NTRS1981

Low NOx heavy fuel combustor concept program

A total of twelve low NOx combustor configurations, embodying three different combustion concepts, were designed and fabricated as modular units. These configurations were evaluated experimentally for exhaust emission levels and for mechanical integrity. Emissions data were obtained in depth on two of the configurations.

White, D. J.↗
NASA NTRS1979

Lean, premixed, prevaporized combustor conceptual design study

Phase 1 of the Lean Premixed-Prevaporized Comubstor Design Study is a nine month analytical study effort with no experimental or testing activities included. The program has the objective to design and analyze advanced combustor concepts with features for fuel premixing and prevaporization upstream of the combustion zone for use in future subsonic aircrafts with features for fuel premixing and prevaporization upstream of the combustion zone for use in future subsonic aircraft engines. All of the designs also embody some form of variable geometry for combustor flow modulation. The primary criterion for these designs is low oxides of nitrogen emissions at stratospheric cruise conditions. Four combustor concepts are being designed for the NASA/GE Energy Efficient Engine (EEE) envelope and cycle. Current status of the program is that the four concepts sized for the EEE were designed and are currently undergoing analysis and evaluation.

Ekstedt, E. E.↗
NASA NTRS1994

Micro-grooved heat transfer combustor wall

A gas turbine engine hot section combustor liner is provided a non-film cooled portion of a heat transfer wall having a hot surface and a plurality of longitudinally extending micro-grooves disposed in the portion of the wall along the hot surface in a direction parallel to the direction of the hot gas flow. The depth of the micro-grooves is very small and on the order of magnitude of a predetermined laminar sublayer of a turbulent boundary layer. The micro-grooves are sized so as to inhibit heat transfer from the hot gas flow to the hot surface of the wall while reducing NOx emissions of the combustor relative to an otherwise similar combustor having a liner wall portion including film cooling apertures. In one embodiment the micro-grooves are about 0.001 inches deep and have a preferred depth range of from about 0.001 inches to 0.005 inches and which are square, rectangular, or triangular in cross-section and the micro-grooves are spaced about one width apart.

Ward, Steven D.↗
NASA NTRS1977

Optically selective, acoustically resonant gas detecting transducer

A gas analyzer is disclosed which responds to the resonant absorption or emission spectrum of a specific gas by producing an acoustic resonance in a chamber containing a sample of that gas, and which measures the amount of that emission or absorption by measuring the strength of that acoustic resonance, e.g., the maximum periodic pressure, velocity or density achieved. In the preferred embodiment, a light beam is modulated periodically at the acoustical resonance frequency of a closed chamber which contains an optically dense sample of the gas of interest. Periodic heating of the absorbing gas by the light beam causes a cyclic expansion, movement, and pressure within the gas. An amplitude is reached where the increased losses were the cyclic radiation energy received. A transducing system is inclined for converting the pressure variations of the resonant gas into electronic readout signals.

Dimeff, J.↗