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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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Pressure Rise, Gas Vibrations and Combustion Noises During the Explosion of Fuels
In the use of piezo-quartz indicators for high-speed automobile engines, the interpretation of pressure-time diagrams made by an oscillograph offers certain difficulties. On the one hand, the scale of the pressure amplitudes is not always the same under all conditions, while, on the other hand, the atmospheric zero line may be shifted from its correct position in the oscillogram. These facts make necessary to verify the readings of the quartz indicators by direct calibration before and after each series of tests and, on the basis of the results, to determine the scale for the oscillograms.
Vocabulary of aerospace safety terms pertaining to cryogenic safety, fires, explosions, and structure failure
This vocabulary listing characterizes the contents of over 10,000 documents of the NASA Aerospace Safety Research and Data Institute's (ASRDI) safety engineering collection. The ASRDI collection is now one of the series accessible on the NASA RECON data base. There are approximately 6,300 postable terms that describe literature in the areas of cryogenic fluid safety, specifically hydrogen, oxygen, liquified natural gas; fire and explosion technology; and the mechanics of structural failure. To facilitate the proper selection of information nonpostable, related and array terms have been included in this listing.
Relativistic blast waves in two dimensions. I - The adiabatic case
Approximate solutions are presented for the dynamical evolution of strong adiabatic relativistic blast waves which result from a point explosion in an ambient gas in which the density varies both with distance from the explosion center and with polar angle in axisymmetry. Solutions are analytical or quasi-analytical for the extreme relativistic case and numerical for the arbitrarily relativistic case. Some general properties of nonplanar relativistic shocks are also discussed, including the incoherence of spherical ultrarelativistic blast-wave fronts on angular scales greater than the reciprocal of the shock Lorentz factor, as well as the conditions for producing blast-wave acceleration.
Partially Ionized Plasma Physics and Technological Applications
Partially ionized plasma physics has attracted increased attention recently due to numerous technological applications made possible by the increased sophistication of computer modelling, the depth of the theoretical analysis, and the technological applications to a vast field of manufacturing for computer components. Partially ionized plasma is characterized by a significant presence of neutral particles in contrast to the fully ionized plasma. The theoretical analysis is based upon solutions of the kinetic Boltzmann equation, yielding the non-Maxwellian electron energy distribution function (EEDF), thereby emphasizing the difference with a fully ionized plasma. The impact of the effect on discharges in inert and molecular gases is described in detail, yielding the complex nonlinear phenomena resulting in plasma selforganization. A few examples of such phenomena are given, including the non-monotonic EEDFs in the discharge afterglow in a mixture of argon with the molecular gas NF3; the explosive generation of cold electron populations in capacitive discharges, hysteresis of EEDF in inductively coupled plasmas. Recently, highly advanced computer codes were developed in order to address the outstanding challenges in plasma technology. These developments are briefly described in general terms.
Explosive hypervelocity launchers
Two stage explosively driven light gas gun to obtain high projectile velocities
Evolution of propulsion systems and the detonation process.
Detonation research in rocket propulsion systems, discussing gas dynamics of explosion harnessing
Infrared observations of Nova Cygni 1975
Infrared photometry from 1 to 20 microns and spectroscopy at about 2 microns are presented for Nova Cygni 1975 for the period from 2 days before to 1 yr after maximum light. The data can be explained by a simple model in which the expanding gas expelled during the explosion is always a plasma at approximately 10,000 K. Initially the gas is optically thick; this phase clearly defines the time of onset of the nova. Later, as the gas continues to expand, it becomes optically thin. The temporal dependence of the observed flux suggests that in this phase the expanding cloud is in the form of a shell. After about 300 days, long-wavelength emission which may be attributable to thermal reradiation from dust is observed.
Improvement of pump tubes for gas guns and shock tube drivers
In a pump tube, a gas is mechanically compressed, producing very high pressures and sound speeds. The intensely heated gas produced in such a tube can be used to drive light gas guns and shock tubes. Three concepts are presented that have the potential to allow substantial reductions in the size and mass of the pump tube to be achieved. The first concept involves the use of one or more diaphragms in the pump tube, thus replacing a single compression process by multiple, successive compressions. The second concept involves a radical reduction in the length-to-diameter ratio of the pump tube and the pump tube piston. The third concept involves shock heating of the working gas by high explosives in a cyclindrical geometry reusable device. Preliminary design analyses are performed on all three concepts and they appear to be quite feasible. Reductions in the length and mass of the pump tube by factors up to about 11 and about 7, respectively, are predicted, relative to a benchmark conventional pump tube.
Laboratory simulation of cratering on small bodies
A new technique using external pressure was developed to simulate the lithostatic pressure due to self-gravity of small bodies. A 13-in. diameter cylindrical test chamber with L/D of 1 was fabricated to accommodate firing explosive charges with gas overpressures of up to 6000 psi. The chamber was hydrotested to 9000 psi. The method allows much larger scale factors that can be obtained with existing centrifuges and has the correct spherical geometry of self gravity. A simulant for jointed rock to be used in this fixture was developed using weakly cemented basalt. Various strength/pressure scaling theories can now be examined and tested.
Helmet-Mounted Display Of Clouds Of Harmful Gases
Proposed helmet-mounted opto-electronic instrument provides real-time stereoscopic views of clouds of otherwise invisible toxic, explosive, and/or corrosive gas. Display semitransparent: images of clouds superimposed on scene ordinarily visible to wearer. Images give indications on sizes and concentrations of gas clouds and their locations in relation to other objects in scene. Instruments serve as safety devices for astronauts, emergency response crews, fire fighters, people cleaning up chemical spills, or anyone working near invisible hazardous gases. Similar instruments used as sensors in automated emergency response systems that activate safety equipment and emergency procedures. Both helmet-mounted and automated-sensor versions used at industrial sites, chemical plants, or anywhere dangerous and invisible or difficult-to-see gases present. In addition to helmet-mounted and automated-sensor versions, there could be hand-held version. In some industrial applications, desirable to mount instruments and use them similarly to parking-lot surveillance cameras.
Exit of a blast wave from a conical nozzle
The Eulerian computer code DORF was used in the analysis of a two-dimensional, unsteady flow field resulting from semi-confined explosions for propulsive applications. Initially, the ambient gas inside the conical shaped nozzle is set into motion due to the expansion of the explosion product gas, forming a shock wave. When this shock front exits the nozzle, it takes almost a spherical form while a complex interaction between the nozzle and compression and rarefaction waves takes place behind the shock. The results show an excellent agreement with experimental data.
Next generation fire suppressants
Spectrex, Inc., located in Cedar Grove, NJ is a manufacturer of fire detection and suppression equipment. Spectrex is one of the original pioneers in high speed fire detection and suppression systems for combat vehicles. Spectrex has installed fire suppressions systems in thousands of combat vehicles and ships throughout the world. Additionally, they manufacture flame explosion detectors, ship damage control systems, and optical gas and vapor detectors. The culmination of several years of research and development has recently produced an innovative electro-optical continuous monitoring systems called SharpEye 20/20I IR(sup 3) and SAFEYE that provide fast and reliable gas, vapor, aerosol, flame, and explosion detection. SharpEye 20/20I IR(sup 3) is a self-contained triple spectrum flame detector which scans for oscillating IR radiation (1 to 10 Hz) in the spectral bands ranging from 4.0 to 5.0 microns and uses programmed algorithms to check the ratio and correlation of data received by the three sensors to make the system highly immune to false alarms. It is extremely sensitive as it can detect a 1 x 1 square foot gasoline pan fire at 200 feet in less than 3 seconds. The sensitivity is user programmable, offering 4 ranges of detection. SAFEYE is comprised of a selected number of multispectral ban microprocessors controlled detectors which are in communication with one or more radiation sources that is projected along a 600 feet optical path. The signals from the selected narrow bands are processed and analyzed by highly sophisticated algorithms. It is ideal for high risk, remote, large areas such as petroleum and chemical manufacturing sites, waste dumps, aircraft cargo bays, and ship compartments. The SAFEYE will perform direct readings of the presence or rate of rise of concentrations of gases, vapors, or aerosols at the range of parts per million and provide alarms at various set points at different levels of concentrations.
Hot bubbles in a magnetic interstellar medium - Another look at the soft X-ray background
An attempt is made to understand the origin and properties of an isolated local bubble of hot gas using models of explosive events in a magnetic interstellar medium which mimic the local bubble in terms of the C band X-ray surface brightness and radius. The residual bubble of hot gas reaches a maximum size with an internal pressure below ambient, and then shrinks to smaller volume and a pressure nearly equal to ambient. The X-ray brightness reaches its minimum at the time of maximum radius and rises thereafter. It is found that the bubble growth must have been confined by a probably unacceptably large external pressure in order for the hot gas in the maximally extended cavity to radiate at a rate like that observed in the soft X-ray background.
On the steady flow of gas from the nuclei of Seyfert galaxies
Heating of gas energy released during explosive events produces hot winds in Seyfert nuclei. Steady-state solutions indicate that supersonic velocities up to about 800 km per sec are obtainable. Lyman continuum radiation emitted by the wind ionizes and maintains temperature of cooler gas clouds seen in emission, and dominates energy losses during early stages of expansion. A study of stability of the thermal equilibrium state leads to a two-component model: a hot stable phase (the wind), in pressure equilibrium with a cooler stable phase (clouds). Extreme variations in cloud electron densities are a consequence of the steep decrease with radius of external pressure. Cloud dynamics are related to the radius of formation and internal parameters. Permitted lines of H are emitted by high-density clouds formed at the base of the wind, while forbidden lines arise in radially moving clouds, produced throughout the wind.
Models of hot galactic coronae around early-type galaxies
We have computed simple non-steady state models of X-ray-emitting, hot galactic coronae which are observed around early-type galaxies. Our models, appropriate for elliptical galaxies, include the effect of the formation of new stars which occurs as the gas radiatively cools and the effect of supernova explosions which serve to heat the cooling gas component from which the stars are forming. We develop scaling relations for the galaxy parameters including the optical galaxy as well as a dark matter halo which we use to generate galaxy models spanning a range of absolute magnitudes from -19.5 to -22.5. We compare our models to a sample of approximately 150 galaxies with measured X-ray luminosities. We show that our simple model does exhibit the observed correlation between X-ray and optical luminosity. However, the model cannot explain the broad range in X-ray luminosity at a given optical luminosity.
Gas clouds in dense star clusters - A possible quasar model.
Gas clouds in dense star clusters compared with quasar properties, analyzing possible energy sources like supernova explosions, stellar collisions and star gas interaction
A multi-Physics Experiment for Low-Yield Nuclear Explosion Monitoring
A series of multi-physics experiments, referred to as Physics Experiment 1 (PE1) is underway at the United States’ Nevada National Security Site (NNSS). The PE1 series includes detonations of three underground chemical explosions in P-tunnel, with fully coupled (PE1 A), partially decoupled (PE1 D L ), and fully decoupled (PE1 B) emplacements. Canisters with gas tracers are imbedded in the explosives, and the tracers are released when the canister is destroyed by the detonation. A dedicated electromagnetic (EM) experiment (EMX) generates well-characterized EM signals at an underground location near the chemical explosive experiments. A series of atmospheric experiments (METEX, REACT, and METREX) release smoke and radioactive tracers around Aqueduct Mesa to test gas transport in complex topography. Each of the chemical explosive experiments includes a network of sensors to record seismic, acoustic, and electromagnetic waves, measurement of atmospheric conditions, and air sample collection for measurement of tracer concentration. EMX records EM signals underground and on the surface of Aqueduct Mesa. METEX, REACT, and METREX include measurement of atmospheric condition, as well as tracking smoke releases. REACT and METREX add low-level radioactive gas tracers to the atmospheric releases.