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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Pressure vessel burst test program. II

The current status is disucssed of a program to study the characteristics of blast waves and fragmentation generated by ruptured gas-filled pressure vessels. Current methods for assessing vessel safety and burst parameters are briefly reviewed, and pneumatic burst testing operations and testing results are examined. A comparison is made with current methods for burst assessment. It is tentatively concluded that, at close distances, vessel burst overpressures are less than those of high-explosive (HE) blasts with equivalent energy and are greater than HE far from the vessel. The impulse appears to be the same for both vessel bursts and equivalent energy HE blasts. The functional relationship between shock velocity and overpressure ratio appears to be the same for vessel bursts as for HE blasts. The initial shock overpressure appears to be much less than vessel pressure and may be found using the one-dimensional shock tube equation.

Cain, Maurice R.↗
NASA NTRS1992

Development of A Non-Explosive Release Device for Aerospace Applications

A simple, non-explosive, high load-capacity release mechanism using shape memory alloy is currently being developed for space flight. This device, the Frangibolt, could replace most pyrotechnic devices in applications where the need for safety, reliability, non-destructive testing, and minimal mechanical shock is more crucial than the need for rapid actuation. Prototype hardware has been designed, tested, and proven in laboratory conditions. Operation and demonstration of these devices evidenced reliable and repeatable performance, clearly indicating that extensive testing for flight qualification is warranted. Here, the Frangibolt design is discussed, recent test results of laboratory units are described, and the work that must be performed in the upcoming months to qualify the device for aerospace applications is addressed.

John D Busch↗
NASA NTRS1993

Calderas produced by hydromagmatic eruptions through permafrost in northwest Alaska

Most hydromagmatic eruptions on Earth are generated by interactions of lava and ground or surface water. This eruptive process typically produces craters 0.1-1 km in diameter, although a few as large as 1-2 km were described. In contrast, a series of Pleistocene hydromagmatic eruptions through 80-100-m-thick permafrost on the Seward Peninsula of Alaska produced four craters 3-8 km in diameter. These craters, called the Espenberg maars, are the four largest maars known on Earth. The thermodynamic properties of ground ice influence the rate and amount of water melted during the course of the eruption. Large quantities of water are present, but only small amounts can be melted at any time to interact with magma. This would tend to produce sustained and highly explosive low water/magma (fuel-coolant) ratios during the eruptions. An area of 400 km(sub 2) around the Alaskan maars shows strong reductions in the density of thaw lakes, ground ice, and other surface manifestations of permafrost because of deep burial by coeval tephra falls. The unusually large Espenberg maars are the first examples of calderas produced by hydromagmatic eruptions. These distinctive landforms can apparently be used as an indicator of the presence of permafrost at the time of eruption.

Beget, J. E.↗
NASA NTRS1993

Joint Acoustic Propagation Experiment (JAPE-91) Workshop

The Joint Acoustic Propagation Experiment (JAPE), was conducted at the White Sands Missile Range, New Mexico, USA, during the period 11-28 Jul. 1991. JAPE consisted of various short and long range propagation experiments using various acoustic sources including speakers, propane cannons, helicopters, a 155 mm howitzer, and static high explosives. Of primary importance to the performance of theses tests was the extensive characterization of the atmosphere during these tests. This atmospheric characterization included turbulence measurements. A workshop to disseminate the results of JAPE-91 was held in Hampton, VA, on 28 Apr. 1993. This report is a compilation of the presentations made at the workshop along with a list of attendees and the agenda.

Willshire, William L., Jr.↗
NASA NTRS1993

Joint Acoustic Propagation Experiment (JAPE)

The Joint Acoustic Propagation Experiment (JAPE), performed under the auspices of NATO and the Acoustics Working Group, was conducted at White Sands Missile Range, New Mexico, USA, during the period 11-28 Jul. 1991. JAPE consisted of 220 trials using various acoustic sources including speakers, propane cannon, various types of military vehicles, helicopters, a 155mm howitzer, and static high explosives. Of primary importance to the performance of these tests was the intensive characterization of the atmosphere before and during the trials. Because of the wide range of interests on the part of the participants, JAPE was organized in such a manner to provide a broad cross section of test configurations. These included short and long range propagation from fixed and moving vehicles, terrain masking, and vehicle detection. A number of independent trials were also performed by individual participating agencies using the assets available during JAPE. These tests, while not documented in this report, provided substantial and important data to those groups. Perhaps the most significant feature of JAPE is the establishment of a permanent data base which can be used by not only the participants but by others interested in acoustics. A follow-on test was performed by NASA LaRC during the period 19-29 Aug. 1991 at the same location. These trials consisted of 59 overflights of supersonic aircraft in order to establish the relationship between atmospheric turbulence and the received sonic boom energy at the surface.

Carnes, Benny L.↗
NASA NTRS1994

Experimental investigation of nozzle/plume aerodynamics at hypersonic speeds

Much of the work involved the Ames 16-Inch Shock Tunnel facility. The facility was reactivated and upgraded, a data acquisition system was configured and upgraded several times, several facility calibrations were performed and test entries with a wedge model with hydrogen injection and a full scramjet combustor model, with hydrogen injection, were performed. Extensive CFD modeling of the flow in the facility was done. This includes modeling of the unsteady flow in the driver and driven tubes and steady flow modeling of the nozzle flow. Other modeling efforts include simulations of non-equilibrium flows and turbulence, plasmas, light gas guns and the use of non-ideal gas equations of state. New experimental techniques to improve the performance of gas guns, shock tubes and tunnels and scramjet combustors were conceived and studied computationally. Ways to improve scramjet engine performance using steady and pulsed detonation waves were also studied computationally. A number of studies were performed on the operation of the ram accelerator, including investigations of in-tube gasdynamic heating and the use of high explosives to raise the velocity capability of the device.

Bogdanoff, David W.↗
DOE OSTI2025

Improved field assessments of chemicals and explosives using high-resolution gamma-ray spectroscopy with a tagged neutron interrogation system

A fi eld-portable tagged neutron interrogation system is being developed for detection of explosives and chemical warfare agents by prompt gamma-ray neutron activation analysis. The system combines an associated particle imaging deuterium-tritium neutron generator with a high-purity germanium gamma-ray detector. Fine spatial resolution neutron and alpha detectors enable precise mapping of characteristic gamma-ray emission distributions onto high-clarity neutron radiographic images. A narrow coincidence gate associated with each tagged neutron ensures a large signal-to-background ratio, thus signifi cantly improving sensitivity to the chemical compositions of the items being assessed. Recent experimental results recorded from test objects involving mock explosives and other chemicals are presented.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
DOE OSTI2025

Improved field assessments of chemicals and explosives using high-resolution gamma-ray spectroscopy with a tagged neutron interrogation system

A fi eld-portable tagged neutron interrogation system is being developed for detection of explosives and chemical warfare agents by prompt gamma-ray neutron activation analysis. The system combines an associated particle imaging deuterium-tritium neutron generator with a high-purity germanium gamma-ray detector. Fine spatial resolution neutron and alpha detectors enable precise mapping of characteristic gamma-ray emission distributions onto high-clarity neutron radiographic images. A narrow coincidence gate associated with each tagged neutron ensures a large signal-to-background ratio, thus signifi cantly improving sensitivity to the chemical compositions of the items being assessed. Recent experimental results recorded from test objects involving mock explosives and other chemicals are presented.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
NASA NTRS1980

A thermalized ion explosion model for high energy sputtering and track registration

A velocity spectrum of neutral sputtered particles as well as a low resolution mass spectrum of sputtered molecular ions was measured for 4.74 MeV F-19(+2) incident of UF4. The velocity spectrum is dramatically different from spectra taken with low energy (keV) bombarding ions, and is shown to be consistent with a hot plasma of atoms in thermal equilibrium inside the target. A thermalized ion explosion model is proposed for high energy sputtering which is expected to describe track formation in dielectric materials. The model is shown to be consistent with the observed total sputtering yield and the dependence of the yield on the primary ionization rate of the incident ion.

Seiberling, L. E.↗
DOE OSTI2025

Improved field assessments of chemicals and explosives using high-resolution gamma-ray spectroscopy with a tagged neutron interrogation system

A field-portable tagged neutron interrogation system is being developed for detection of explosives and chemical warfare agents by prompt γ-ray neutron activation analysis. The system combines an associated particle imaging deuterium-tritium neutron generator with a high-purity germanium γ-ray detector. Fine spatial resolution neutron and α detectors enable precise mapping of characteristic γ-ray emission distributions onto high-clarity neutron radiographic images. A narrow coincidence gate associated with each tagged neutron ensures a large signal-to-background ratio, thus significantly improving sensitivity to the chemical compositions of the items being assessed. Recent experimental results recorded from test objects involving mock explosives and other chemicals are presented.

Bucher, Brian [Idaho National Laboratory (INL)]↗
NASA NTRS1995

Effect of particle size and particle size distribution on physical characteristics, morphology and crystal structure of explosively compacted high-T(sub c) superconductors

A superconductor, of composition Y(Ba,K,Na)2Cu3O(x)/F(y) and a composite of composition Y(Ba,K,Na)2Cu3O(x)/F(y) + Ag, with changing K, Na and F content but a constant silver content (Ag = 10 mass%) was prepared using a single heat treatment. the resulting material was ground in a corundum lined mill, separated to particle size fractions of 0-40 micron, 0-63 micron and 63-900 micron and explosively compacted, using an explosive pressure of 10(exp 4) MPa and a subsequent heat treatment. Best results were obtained with the 63-900 micron fraction of composition Y(Ba(1.95) K(0.01)Cu3O(x)F(0),(05)/Ag: porosity less than 0.01 cu cm/g and current density 2800 A/sq cm at 77K.

Kotsis, I.↗
NASA NTRS2005

On the Interaction and Coalescence if Spherical Blast Waves

The scaling and similarity laws concerning the propagation of isolated spherical blast waves are briefly reviewed. Both point source explosions and high pressure gas explosions are considered. Test data on blast overpressure from the interaction and coalescence of spherical blast waves emanating from explosives in the form of shaped charges of different strength placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure. The results point out the possibility of detecting source explosions from far-field pressure measurements.

Kandula, Max↗
DOE OSTI2025

Physics-driven Explosions of Stripped High-mass Stars: Synthetic Light Curves and Spectra of Stripped-envelope Supernovae with Broad Light Curves

Stripped-envelope supernovae (SESNe) represent a significant fraction of core-collapse supernovae, arising from massive stars that have shed their hydrogen and, in some cases, helium envelopes. The origins and explosion mechanisms of SESNe remain a topic of active investigation. In this work, we employ radiative-transfer simulations to model the light curves and spectra of a set of explosions of single, solar-metallicity, massive Wolf–Rayet stars with ejecta masses ranging from 4 to 11 M ⊙ , which were computed from a turbulence-aided and neutrino-driven explosion mechanism. We analyze these synthetic observables to explore the impact of varying ejecta mass and helium content on observable features. We find that the light curve shape of these progenitors with high ejecta masses is consistent with observed SESNe with broad light curves but not the peak luminosities. The commonly used analytic formula based on rising bolometric light curves overestimates the ejecta mass of these high-initial-mass progenitor explosions by a factor of up to 2.6. In contrast, the calibrated method by Haynie et al., which relies on late-time decay tails, reduces uncertainties to an average of 20% within the calibrated ejecta mass range. Spectroscopically, the He I 1.083 μm line remains prominent even in models with as little as 0.02 M ⊙ of helium. However, the strength of the optical He I lines is not directly proportional to the helium mass but instead depends on a complex interplay of factors such as the 56 Ni distribution, composition, and radiation field. Thus, producing realistic helium features requires detailed radiative transfer simulations for each new hydrodynamic model.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1975

Mass distribution of orbiting man-made space debris

Three ways of producing space debris were considered, and data were analyzed to determine mass distributions for man-made space debris. Hypervelocity (3.0 to 4.5 km/sec) projectile impact with a spacecraft wall, high intensity explosions and low intensity explosions were studied. For hypervelocity projectile impact of a spacecraft wall, the number of fragments fits a power law. The number of fragments for both high intensity and low intensity explosions fits an exponential law. However, the number of fragments produced by low intensity explosions is much lower than the number of fragments produced by high intensity explosions. Fragment masses down to 10 to the -7 power gram were produced from hypervelocity impact, but the smallest fragment mass resulting from an explosion appeared to be about 10 mg. Velocities of fragments resulting from hypervelocity impact were about 10 m/sec, and those from low intensity explosions were about 100 m/sec. Velocities of fragments from high intensity explosions were about 3 km/sec.

Bess, T. D.↗
DOE OSTI2026

Exploding Bridgewire (EBW) Detonators: An Example of Synergistic Multiphysics

Exploding bridgewire (EBW) detonators are highly temporally reproducible explosive devices that require the rapid discharge of a high‐voltage capacitance to operate and so are immune to most of the accidental hazards associated with traditional electric detonators. They have been demonstrated to be safe enough for use in high‐consequence explosive applications. Despite continued use for over 82 years, understanding the exact mechanism of operation has remained elusive. Various researchers have ascribed either deflagration‐to‐detonation (DDT) or shock‐to‐detonation (SDT) phenomena observed in other explosive events to explain the science behind the successful engineering; however, a rigorous justification has been absent. Previously, we have demonstrated a complex interaction in EBW detonators between large electrical currents, non‐equilibrium thermodynamic material states, plasma physics, powder compaction phenomena, shock physics, photochemistry, and rapid conventional explosive chemical reaction processes. Specifically, we have made progress in understanding the complex multiphysics that operates in these detonators and demonstrating that it is a serendipitous synergy between UV light emitted from the arc formed as the bridge is electrically exploded and the accompanying short‐duration shock transmitted into the explosive powder bed that allows these devices to function at practical capacitor sizes and charge voltages. This insight not only places the topic on a firmer scientific footing but potentially enables new approaches to safe detonator design.

36 MATERIALS SCIENCE↗